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Pulse Response Measurement Optimization of ReRAM-Based Neuromorphic Devices
Soon Joo Yoon, Yoon Kyeung Lee
J Electr Electron Mater 2026;39(3):258-266.
Published online May 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.3.4
The rapid advancement of large-scale language models and artificial intelligence technologies has highlighted the importance of data processing efficiency. This study outlines a measurement optimization method for high-speed pulse equipment to accurately analyze the operating dynamics of ReRAM, a core hardware component for simulating neural networks. An optimized evaluation methodology combining connection compensation and a dual-channel configuration was established to minimize measurement errors caused by parasitic resistance and capacitance during pulse measurements using the Keithley 4200A-SCS and 4225-PMU modules, and to address HRS/LRS measurement errors caused by mismatches between the measurement range and source limits. The proposed precision measurement guidelines can be applied to the evaluation of semiconductor devices that require pulse measurements, such as transistors and DRAM.
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A Study on the Explosion Characteristics of Off-Gases from Lithium-Ion Battery Thermal Runaway for EVs Marine Transport Safety
Jeong-hoon Park, In-chul Park
J Electr Electron Mater 2026;39(1):52-58.   Published online January 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.1.6
As electric vehicles (EVs) are rapidly adopted worldwide, large numbers are now transported by sea on dedicated car carriers. With this trend, concerns are increasing about fires and explosions caused by battery thermal runaway during marine transport, while existing SOC limits before loading remain largely empirical. This study experimentally investigates gas generation and explosion characteristics of EV lithium-ion cells under thermal runaway conditions representative of enclosed vehicle decks. We identify and quantify the main off-gas components and clarify the flammability behavior and explosion limits of key combustible species. The results provide basic data for assessing EV battery accidents at sea and support the development of safer ventilation and gas-management strategies for ships.
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Dielectric Characteristics of (BaCaSr)(TixZr1-x)O3 Dielectric Ceramic with Temperature Compensation Capacitor Characteristics
Yoo Jung Choi, Hong Sun Lee, Jung Rag Yoon
J Electr Electron Mater 2025;38(4):376-382.   Published online July 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.4.4
This study developed a dielectric composition for high-capacitance MLCCs with C0G and U2J temperature compensation characteristics (Class I) under reducing conditions. The potential application of this composition in highpermittivity class I MLCCs was examined. Using (Ba₀.₂₄Ca₀.₁₆Sr₀.₆)(TiₓZr₁₋ₓ)O₃. XRD analysis showed that secondary phases like Sr₂TiO₄ and TiO₂ formed at higher Ti content, affecting the stoichiometric balance. Adjusting the Ti/Zr molar ratio resulted in a dielectric constant of 41.2 ~ 105, a dielectric loss of 0.082 ~ 0.174%, and insulation resistance above 1.6 × 1013 ohms at 25℃. The TCC shifted from C0G to U2J as the Ti/Zr ratio increased, but the composition enabled the design of high-capacitance and high-voltage MLCCs with favorable dielectric and electrical properties.
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Always Space Antibacterial Technology Using a Luminaire Applied with a Visible Light Catalyst
Doowon Jang, Chunghyeok Kim
J Electr Electron Mater 2024;37(5):512-518.   Published online September 1, 2024
DOI: https://doi.org/10.4313/JKEM.2024.37.5.7
Titanium oxide (TiO₂), a representative photocatalyst, reacts to ultraviolet ray energy and has antibacterial, deodorizing, and antifouling properties using superhydrophilic properties, so it is widely used in various industrial fields such as environmental purification, building exterior walls, and road facilities. However, due to the nature of the photocatalyst, it reacts to ultraviolet rays known to be harmful to the human body, and is designed to react to natural light outdoors and to ultraviolet light sources inside a sealed device indoors, so indoor space is extremely limited. This study aims to develop spatial antibacterial technology for everyday living spaces by researching methods for antibacterial and deodorization by reacting titanium oxide (TiO₂)-based photocatalysts with the visible light range emitted from lighting devices in everyday spaces. Through the results of this study, it was verified through experiments that the photocatalyst exhibits antibacterial and deodorizing properties in response to lighting devices (LED, fluorescent lights, etc.) used in daily life. Based on the research results, we hope that various studies will be conducted to create a safer living environment by applying this technology to various fields such as large-scale complex facilities where an unspecified number of floating populations gather, airports, port waiting rooms, and public transportation.
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Analysis on Fault Current Limiting Characteristics of Three-Phase Transformer Type SFCL using Double Quench According to Three-Phase Ground-Fault Types
Shin-won Lee, Tae-hee Han, Sung-hun Lim
J Electr Electron Mater 2023;36(6):614-619.   Published online November 1, 2023
DOI: https://doi.org/10.4313/JKEM.2023.36.6.13
The fault current limiting characteristics of three-phase transformer type superconducting fault current limiter (SFCL), which consisted of three-phase primary and secondary windings wound on E-I iron core, one high-TC superconducting (HTSC) element connected with the secondary winding of one phase and another HTSC element connected in parallel with other two secondary windings of two phases, were analyzed. Unlike other three-phase transformer type SFCLs with three HTSC elements, three-phase transformer type SFCL using double quench has the merit to perform fault current limiting operation for three-phase ground faults with two HTSC elements. To verify its proper three-phase ground fault current limiting operation, three-phase ground faults such as single-line ground, double-line ground and triple-line ground faults were generated in three-phase simulated power system installed with three-phase transformer type SFCL using double quench. From analysis of its fault current limiting characteristics based on tested results, three-phase transformer type SFCL using double quench was shown to be effectively operated for all three-phase ground faults.
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Effect of CNTs on Electrical Properties and Thermal Expansion of Semi-conductive Compounds for EHV Power Cables
Jae-gyu Han, Jae-shik Lee, Dong-hak Kim
J Electr Electron Mater 2023;36(6):603-608.   Published online November 1, 2023
DOI: https://doi.org/10.4313/JKEM.2023.36.6.11
Carbon black with high purity and excellent conductivity is used as a conductive filler in the semiconductive compound for EHV (Extra High Voltage) power cables of 345 kV or higher. When carbon black and CNT (carbon nanotube) are applied together as a conductive filler of a semiconductive compound, stable electrical properties of the semiconductive compound can be maintained even though the amount of conductive filler is significantly reduced. In EHV power cables, since the semi-conductive layer is close to the conductor, stable electrical characteristics are required even under high-temperature conditions caused by heat generated from the conductor. In this study, the theoretical principle that a semiconductive compound applied with carbon black and CNT can maintain excellent electrical properties even under high-temperature conditions was studied. Basically, the conductive fillers dispersed in the matrix form an electrical network. The base polymer and the matrix of the composite, expands by heat under high temperature conditions. Because of this, the electrical network connected by the conductive fillers is weakened. In particular, since the conductive filler has high thermal conductivity, the semiconductive compound causes more thermal expansion. Therefore, the effect of CNT as a conductive filler on the thermal conductivity, thermal expansion coefficient, and volume resistivity of the semiconductive compound was studied. From this result, thermal expansion and composition of the electrical network under high temperature conditions are explained.
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Module Characteristic Modeling in Terms of the Number of Divisions of Large-Area Solar Cells
Juhwi Kim, Jaehyeong Lee
J Electr Electron Mater 2023;36(2):136-142.   Published online March 1, 2023
DOI: https://doi.org/10.4313/JKEM.2023.36.2.5
In the past, the efficiency of solar cells had been increased in order to increase the efficiency of solar modules. However, in recent years, in order to increase output in the solar industry and market, the competitiveness of solar cells based on large-area solar cells and multi-bus bar has been increasing. Multi-busbar solar module is a technology to reduce power loss by increasing the number and width of the front busbar of the solar cell and reducing the current value delivered by the busbar by half through half-cutting. In the case of the existing M2 (156.75×156.75 ㎟) solar cell, even with a half-cut, power loss could be sufficiently reduced, but as the area of the solar cell is enlarged to more than M6 (166×166 ㎟), the need for more divisions emerged. This affected not only solar cells but also inverters required for module array configuration. Therefore, in this study, the electrical characteristics of a large-area solar cell and after division were extracted using Griddler simulation. The output characteristics of the module were predicted by applying the solar cell parameters after division to PSPice, and a guideline for the large-area solar module design was presented according to the number of divisions of the large-area solar cell.
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Study on Characteristics of Write Discharge with Single Sustain Waveform in AC Plasma Display Panel
Byung-gwon Cho
J Electr Electron Mater 2023;36(1):56-61.   Published online January 1, 2023
DOI: https://doi.org/10.4313/JKEM.2023.36.1.9
The characteristics of write discharge were investigated when the conventional driving method with the unipolar sustain voltages, and the single sustain driving method applying the bipolar sustain voltage were applied in an AC plasma display. In the case of having a single sustain waveform, the strength of the write discharge is weakened compared to the conventional driving method during the address period, because the wall charge inside the panel is more dissipated by the lower scanning voltage. In the driving method with a single sustain waveform, the bias voltage of the other electrodes was changed to improve the write discharge characteristics. As a result, the intensity of the discharge was enhanced by 32% and the delay time was shortened by 60 μs.
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Optimization Study for Material Properties of Piezoelectric Material Using Parameter Estimation Method: Part I. Polycrystal PZT Ceramics
Ho-yong Shin, Ho-yong Lee, Il-gok Hong, Jong-ho Kim, Jong-in Im
J Electr Electron Mater 2022;35(5):471-479.   Published online September 1, 2022
DOI: https://doi.org/10.4313/JKEM.2022.35.5.8
Recently, piezoelectric devices, such as ultrasonic surgery, ultrasonic atomizer, and ultrasonic speaker, are analyzed and designed by finite element simulation methods. However, the discrepancy between the design and the experiment results of the device typically occurs due to the inaccuracy of the piezoelectric material properties. To improve the simulation accuracy, the material properties of the PZT ceramics were better refined using parameter estimation method. The material parameters are elastic stiffness cEij and piezoelectric constant eij of PZT ceramics. The impedance curve characteristics for the LTE mode of PZT ceramics were calculated. The mismatch between the simulation and the experimental data were compared and minimized by a least square method. Finally, the simulated impedance data were compared with the experimental data for the various vibration modes of PZT ceramics and the optimized material properties of PZT ceramics were verified. To further verify the accuracy, this method was also applied to piezoelectric PMN-PT single crystals.
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The subthreshold swing (SS) of an asymmetric junctionless double gate (AJLDG) MOSFET is analyzed by the use of Gaussian function. In the asymmetric structure, the thickness of the top/bottom oxide film and the flat-band voltages of top gate (Vfbf) and bottom gate (Vfbb) could be made differently, so the change in the SS for these factors is analyzed with the projected range and standard projected deviation which are parameters for the Gaussian function. An analytical subthreshold swing model is presented from the Poisson’s equation, and it is shown that this model is in a good agreement with the numerical model. As a result, the SS changes linearly according to the geometric mean of the top and bottom oxide film thicknesses, and if the projected range is less than half of the silicon thickness, the SS decreases as the top gate oxide film is smaller. Conversely, if the projected range is bigger than a half of the silicon thickness, the SS decreases as the bottom gate oxide film is smaller. In addition, the SS decreases as Vfbb-Vfbf increases when the projected range is near the top gate, and the SS decreases as Vfbb-Vfbf decreases when the projected range is near the bottom gate. It is necessary that one should pay attention to the selection of the top/bottom oxide thickness and the gate metal in order to reduce the SS when designing an AJLDG MOSFET.
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Effect of Structure Change in Second-Generation Superconducting Wire Stabilization Layer on Resistivity Characteristics
Sang-jae Ban, Ho-ik Du, Hyun-gi Jeong, Seung-gyu Doo, Sung-chae Yang
J Electr Electron Mater 2022;35(2):172-177.   Published online March 1, 2022
DOI: https://doi.org/10.4313/JKEM.2022.35.2.10
The quench voltage of the second-generation superconducting wire is affected by the resistivity characteristics of the stabilization layer. The specific resistance of the stabilization layer can be changed by the deposition process using RF magnetron sputtering. In this paper, a thin film made of a homogeneous material (Ag) and a dissimilar material (Cu) was deposited on the stabilization layer of the second-generation superconducting wire through RF magnetron sputtering. We found that the specific resistance was reduced by increasing the thickness of the stabilization layer. The reduction in the resistivity of the stabilization layer led to a decrease in the quench voltage of the second-generation superconducting wire. We suggest that various characteristic changes of the second-generation superconducting wire can be expected through the successful change in the resistivity of the stabilization layer of the proposed deposition process.
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A Study on the Exothermic Properties of ITO/Ag/ITO Multilayer Transparent Electrode Depending on Metal Layer Thickness
Hye-jin Min, Ye-jina Kang, Hye-won Son, So-hyun Sin, Min-ho Hwang, Hyun-yong Lee
J Electr Electron Mater 2022;35(1):37-43.   Published online January 1, 2022
DOI: https://doi.org/10.4313/JKEM.2022.35.1.6
In this study, we investigated the optical, electrical and exothermic characteristics of ITO/Ag/ITO multilayer structures prepared with various Ag thicknesses on quartz and PI substrates. The transparent conducting properties of the ITO/Ag/ITO multilayer films depended on the thickness of the mid-layer metal film. The ITO/Ag (14 nm)/ITO showed the highest Haccke’s figure of merit (FOM) of approximately 19.3×10-3 Ω-1. In addition, the exothermic property depended on the substrate. For an applied voltage of 3.7 V, the ITO/Ag (14 nm)/ITO multilayers on quartz and PI substrates were heated up to 110℃ and 200℃, respectively. The bending tests demonstrated a comparable flexibility of the ITO/Ag/IT multilayer to other transparent electrodes, indicating the potential of ITO/Ag/ITO multilayer as a flexible transparent conducting heater.
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In this study, solder joints mixed with graphene-nanosheets (GNSs) were investigated for the manufacture of highly reliable electronic devices. In order to analyze the effect of adding GNSs, experiments were performed by adding various amounts of GNSs (0.01, 0.05, 0.1, 0.3, 0.5 wt%). To compare and analyze the properties of the solder joints to which GNSs were added, shear forces were measured, and cross-sectional observation was performed. The bonding strength of the solder joints containing 0.05% GNSs was the highest, and the bonding strength of the solder joints with higher GNSs contents did not increase. This is because, as the content of GNSs increases, the viscosity of the solder paste also increases; therefore, the solder paste detachability from the metal mask was lowered and a sufficient amount was not applied. In addition, due to the high content of GNSs, the fluidity of solder powder and paste decreased, resulting in defects in the shape of the solder joint. Therefore, the optimal GNSs content in this study was 0.05%, and studies for optimal viscosity should be continued.
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Process Parameter Control of Arc Melting Process for Ti3SiC2 MAX Phase Synthesis
Chang Wan Nou, Byeong Guen Kim, Sang Hyun Bae, Soon-mok Choi
J Electr Electron Mater 2020;33(6):515-520.   Published online November 1, 2020
DOI: https://doi.org/10.4313/JKEM.2021.33.6.16
The Ti3SiC2 MAX phase was synthesized by arc-melting process under three different processing times. We confirmed that the reaction between the TiCX phase and Ti-Si liquid phase is important for the synthesis of the Ti3SiC2 MAX phase. Results suggest that the Ti3SiC2 MAX phase decomposed when the arc-melting time was greater than 80s. Herein, we aim to determine the detailed parameters for the reported arc-melting process, which can provide useful insights on the synthesis of the Ti3SiC2 MAX phase by arc-melting process. Furthermore, we compared the electrical characteristics and densities of the three samples.
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Effect of Starting Powder on the Growth of BaTiO3 Film Prepared by Aerosol Deposition Process
Myung-yeon Cho, Ik-soo Kim, Dong-won Lee, Sang-mo Koo, Jong-min Oh
J Electr Electron Mater 2020;33(3):208-213.   Published online May 1, 2020
DOI: https://doi.org/10.4313/JKEM.2021.33.3.9
Four types of BaTiO3 powders are prepared and successfully deposited on glass and Pt/Si substrates using the aerosol deposition process. Particles with sizes of 0.45 μm and 0.3 μm are selected as the starting powder, while those powders are treated using a different milling method. The jet-milled and ball-milled powders not only showed a smaller particle-size distribution, but compared with the non-milled powder, it also had a higher deposition rate using the uniformly generated aerosol. Although the films deposited using particles with size 0.45 μm exhibited some craters on the surface, significantly flat film surfaces were obtained. However, particles with size 0.3 μm create a slightly rough film surface, but the dielectric constant was greater than in the case involving particles with size 0.45 μm. Consequently, a suitably large particle size significantly influences the deposition rate and improvement in the surface roughness, and a uniform particle size distribution appears to contribute to an improved dielectric constant. Therefore, it is believed that the dielectric properties along with the growth characteristics can be enhanced by limiting particle size and shape.
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Preparation and Characterization of Swallow-Tail Terrylene Bisimide as Organic Phosphor
Sung Bong Jung, Yeon Tae Jeong
J Electr Electron Mater 2020;33(3):194-200.   Published online May 1, 2020
DOI: https://doi.org/10.4313/JKEM.2021.33.3.7
Perylene bisimide derivatives are developed for red organic phosphor because of their advantages, such as excellent luminous efficiency and high thermal stability. Despite these advantages, they have poor solubility characteristics in organic solvents and short emission wavelength as red organic phosphor for hybrid light-emitting diodes (LEDs). In this study, we prepared terrylene bisimide using a coupling reaction and swallow-tail imide group, which has excellent solubility. The structures and properties of swallow-tail terrylene bisimide (9C) were analyzed using 1H-nuclear magnetic resonance (1H-NMR), Fourier-transform infrared (FT-IR), UV/Vis spectroscopy, and thermal gravimetric analysis (TGA). The maximum absorption wavelength of (9C) in the UV/Vis spectrum was 647 nm, and the maximum emission wavelength was 676 nm. In the TGA, (9C) demonstrated good thermal stability with less than 5 wt% weight loss up to 415℃. In the solubility test, (9C) has a good solubility of more than 5 wt% in chloroform and dichloromethane. When the compounds (9C) were mixed with PMMA (polymethly methacrylate), the films showed peaks at 680 nm in the PL spectra. The results verify the suitability of (9C) as a red organic phosphor for hybrid LEDs.
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Evaluation of Electrical Properties of IZO Thin-Film with UV Post-Annealing Treatment Time
Jae-yun Lee, Han-sang Kim, Sung-jin Kim
J Electr Electron Mater 2020;33(2):93-98.   Published online March 1, 2020
DOI: https://doi.org/10.4313/JKEM.2021.33.2.3
We investigated the effect of a post-annealing process using ultraviolet (UV) light on the electrical properties of solution-processed InZnO (IZO) thin-film transistors (TFTs). UV light was irradiated on IZO TFTs for different time periods of 0s, 30s, and 90s. We measured transfer and retention stability curves to evaluate the performance of the fabricated TFTs. In addition, we measured height, amplitude, and phase AFM images to analyze changes in the surface and morphology of the devices. AFM measurements were performed by setting the drive amplitude of the cantilever tip to 47.9 mV in tapping mode, then dividing the device surface into 500 nm × 500 nm. In the case of IZO TFT irradiated with UV for 30s, the electron mobility and Ion/Ioff ratio were improved, the threshold voltage was reduced by approximately 2 V, and the subthreshold swing also decreased form 1.34 V/dec to 1.11 V/dec.
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Determination of Deterioration and Damage of Porcelain Insulators in Power Transmission Line Through Mechanical Analysis
Ju-am Son, In-hyuk Choi, Ja-bin Koo, Taeyong Kim, Seongho Jeon, Youn-jung Lee, Junsin Yi
J Electr Electron Mater 2020;33(1):50-55.   Published online January 1, 2020
DOI: https://doi.org/10.4313/JKEM.2021.33.1.10
Porcelain insulators have been used for a long time in 154 kV power transmission lines. They are likely to be exposed to sudden failure because of product deterioration. This study was conducted to evaluate the quality of porcelain insulators. After stresses were applied, the damaged regions of aged insulators were investigated in terms of chemical composition, material structure, and other properties. For porcelain insulators that were in service for a long time, the mechanical failure load was 126 kN, whereas the average mechanical failure load was 167.3 kN for new products. It was also determined that corrosion occurred at the metal pin part due to the penetration of moisture into the gap between the pin and the ceramic. Statistical analyses of failure were performed to identify the portion of the insulators that were broken. Cristobalite porcelain insulators fabricated without alumina additives had a high failure rate of 54% for the porcelain component. In the case of the addition of Alumina (Al2O3) to the porcelain insulators to improve the strength of the ceramic component, a more frequent damage rate of the cap and pin of 73.3% and 27%, respectively, was observed. This study reports on the material component of SiO2 and the percentage of alumina added, with respect to the mechanical properties of porcelain insulators.
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Analysis of Electrical Characteristics Due to Deterioration of Electromagnetic Contactor
Sun-ho Choi
J Electr Electron Mater 2019;32(5):407-412.   Published online September 1, 2019
In this paper, the changes in the electrical characteristics (arc energy, contact resistance, and bouncing phenomenon) due to the deterioration of the contact are analyzed. The results are generally consistent and can be analyzed for contact deterioration. The results of the experiment demonstrate that the arc energy is linearly related to the current when the contact samples and the voltage conditions are the same. The contact resistance varies due to multiple factors, but is generally within a certain range, and the contact deterioration can be determined. Contact stabilization can be detected by the decrease in the bouncing phenomenon due to deterioration (the change of the shape of the contact).
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Electrical Properties of Plate Typed Shunt Resistors with Low TCR Property
Youngtaek Lim, Eun-min Kim, Sang-won Lee, Jeong-rae Ahn, Sunwoo Lee
J Electr Electron Mater 2019;32(3):219-222.   Published online May 1, 2019
In this study, we fabricated plate-type shunt resistors with thermal stability by parallelly connecting metal alloy plates with positive temperature coefficient of resistance (TCR) and carbon nanotube (CNT) plates with negative TCR. The metal alloy plates, which were prepared by alloying Cu and Mn with a composition of 91 wt% of Cu and 9 wt% of Mn, showed around 800 ppm/℃ of TCR, and the CNT plates prepared from the CNT solution by using the vacuum filtration method showed around -800 ppm/℃ of TCR. The shunt resistor that was fabricated by stacking metal alloy plates and CNT plates in this work showed about 46.93 ppm/℃ of TCR. Therefore, we conclude that a shunt resistor with low TCR can be realized by simply adjusting the TCR of the metal alloy only, because the TCR of the CNT plate has an identical value.
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Electrical Characteristics of Pressure Device with Graphene Oxide Composite Structure
Yong Woo Kim, Gi Yeon Roh, Hyeong Seok Sung, Woo Jin Choi, Yong Jae Ahn, Seong Eui Lee
J Electr Electron Mater 2019;32(2):93-99.   Published online March 1, 2019
A pressure sensor is a device that converts an applied physical pressure into an electrical signal. Such sensors have a range of applications depending on the pressure level, from low to high pressure. Sensors that use physical pressure, when compared to those operating under air pressure, are not widely applied as they are inefficient. To solve this problem, graphene oxide, which exhibits good mechanical and electrical characteristics, was used to increase the efficiency of these pressure sensors. Graphene oxide has properties that control the movement of charges within the dielectric. Exploiting these properties, we evaluated the change in electrical characteristics when pressure was applied according to the ratio and thickness of the oxidation graph added to the pressure sensor.
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Synthesis and Characterization of Swallow-Tail Perylene Bisimide as Organic Phosphor for Hybrid LED
Sung Bong Jung, Yeon Tae Jeong
J Electr Electron Mater 2019;32(1):86-92.   Published online January 1, 2019
Although perylene bisimide derivatives have advantages such as excellent thermal stability and high luminance efficiency, they have poor solubility characteristics in organic solvents. In this research, in order to improve the solubility characteristics, we prepared perylene bisimide derivatives (1C) and (2C) with swallow-tail substituted imide, which is known to lead to excellent solubility. The structures and properties of swallow-tail perylene bisimide (1C) and (2C) were analyzed by 1H-NMR, FT-IR, UV/Vis spectroscopy, and thermogravimetric analysis (TGA). The maximum absorption wavelengths of (1C) and (2C) in the UV/Vis spectrum were 558 nm and 556 nm, respectively, and the maximum emission wavelengths were 602 nm and 600 nm, respectively. In the TGA, (1C) demonstrated good thermal stability with less than 5 wt% weight loss up to 242℃. In the solubility test, (1C) and (2C) exhibited solubilities of more than 5 wt% in chloroform, ethyl acetate, and dimethylformamide, but not in methanol. When the compounds (1C) and (2C) were mixed with PMMA (polymethyl methacrylate), thin films showed peaks at 679 nm and 677 nm, respectively, in the photoluminescence spectra. (1C) was found to be a possible candidate as red organic phosphor for hybrid LEDs.
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Behavior of the Temperature Coefficient of Resistance at Parallelly Connected Resistors
Sunwoo Lee
J Electr Electron Mater 2018;31(2):98-101.   Published online February 1, 2018
In this paper, we discuss the fabrication of metal alloy resistors. We connected them in parallel to estimate their resistance and temperature coefficient of resistance (TCR). The fabricated resistors have different resistances, 5 and 10 Ω and different TCRs, 50 and 200 ppm/℃. Each resistor was confirmed to have the correct atomic composition through the use of energy dispersive X-ray (EDX). The resistors’ electrical properties were confirmed by measuring resistance and TCR. The resistance and TCR of the resistors connected in parallel were estimated through the increase in resistance due to the increase in temperature, and were compared with the measured values. We are confident that this TCR estimation technique, which uses the increase in resistance due to temperature, will be very useful in designing and fabricating resistors with low and stable TCR.
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Effect of Porcelain/Polymer Interface on the Microstructure, Insulation Characteristics and Electrical Field Distribution of Hybrid Insulators
Jun-young Cho, Woo-seok Kim, Ho-sung An, Hee-sung An, Tae-wan Kim, Yun-seog Lim, Sung-hwan Bae, Chan Park
J Electr Electron Mater 2017;30(9):558-565.   Published online September 1, 2017
Hybrid insulators that have the advantages of both porcelain (high mechanical strength and chemical stability) as well as polymer (light weight and high resistance to pollution) insulators, can be used in place of individual porcelain and polymer insulators that are used for both mechanical support as well as electrical insulation of overhead power transmission lines. The most significant feature of hybrid insulators is the presence of porcelain/polymer interfaces where the porcelain and polymer are physically bonded. Individual porcelain and polymer insulators do not have such porcelain/polymer interfaces. Although the interface is expected to affect the mechanical/electrical properties of the hybrid insulator, systematic studies of the adhesion properties at the porcelain/polymer interface and the effect of the interface on the insulation characteristics and electric field distribution of the hybrid insulator have not been reported. In this study, we fabricated small hybrid insulator specimens with various types of interfaces and investigated the effect of the porcelain/polymer interface on the microstructure, insulating characteristics, and electric field distribution of the hybrid insulators. It was observed that the porcelain/polymer interface of the hybrid insulator does not have a significant effect on the insulating characteristics and electric field distribution, and the hybrid insulator can exhibit electrical insulating properties that are similar or superior to those of individual porcelain and polymer insulators.
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A Study on the Analysis of the Output Characteristics of the Floating Photovoltaic System
Won Yong Choi, Jae-hyeong Lee, Sung-hoon Choa
J Electr Electron Mater 2017;30(5):312-317.   Published online May 1, 2017
In this paper, the effects of environmental variables on the output of the floating photovoltaic water systems, which were installed at the Hapcheon dam in South Korea, were investigated, and the correlations between them were analyzed. The system output was linearly proportional to the solar radiation or irradiance. The output was large in spring and autumn because of high irradiance, but low in the summer when the solar module temperature was high. The influence of the module temperature on the system output was limited in the summer, during which the module temperature change affected the system output more than the change of the irradiance did. In addition, in winter and summer, the module temperature tended to decrease with increasing windspeed, but windspeed did not affect module temperature significantly in the spring and autumn. On the other hand, in winter and spring, the irradiance decreased as the windspeed increased because of movement (or circulation) of the photovoltaic modules.
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Development of Blue Fluorescent Light Hole Transport Layer of Thiophene Base
Hyun-chul Ki, Hyeon Oh Shin, Eun Hye Hwang, Tae-hyuk Kwon
J Electr Electron Mater 2017;30(2):91-95.   Published online February 1, 2017
We were designed the hole transport layer of the new composite skeleton structure having a high charge mobility and thermal stability. In this paper, a hole transport layer material based on thiophene molecular structure capable of hole mobility characteristics and high triplet energy was designed and synthesized. The structures and properties of the synthesized compounds were characterized by NMR, fluorescence spectroscopy and energy band gap. As a result of NMR measurement, it was confirmed that when analyzing the integrated type with the position where the measured peak is displayed, it agrees with the structure of hole transport materials. The emission characteristics of the hole transport layer material showed absorption characteristics at 412 nm and 426 nm, respectively, and exhibited emission characteristics in the range of 469 nm and 516 nm.
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Transient Current Limiting Characteristics of Flux-Lock Type SFCL Using Double Quench
Sang-jae Choi, Sung-hun Lim
J Electr Electron Mater 2017;30(2):96-100.   Published online February 1, 2017
In this paper, the flux-lock type superconducting fault current limiter (SFCL) using double quench was suggested and its transient current limiting characteristics were analyzed. The suggested flux-lock type SFCL using double quench consists of two magnetically coupled windings and two high-TC superconducting (HTSC) elements connected in series with each winding. To analyze the transient current limiting characteristics of the flux-lock type SFCL using double quench, the short-circuit tests according to the fault angles, which affect the transient component of the fault current right after the fault occurs, were executed. From the comparative analysis for the short-circuit tests at both 0° and 90° fault angles, the useful transient current limiting operations of the suggested flux-lock type SFCL through the double or the single quench occurrence were confirmed.
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Comparative Analysis on Magnetization Characteristics and Stored Energy of Magnetically Coupled SFCLs Using Single and Double HTSC Elements
Sang-jae Choi, Bo-hee Kim, Sung-hun Lim
J Electr Electron Mater 2017;30(2):101-105.   Published online February 1, 2017
In this paper, the magnetization characteristics and the stored energy of magnetically coupled superconducting fault current limiter (SFCL)s using single and double high-Tc superconducting (HTSC) elements were compared. To analyze the magnetization characteristics and the stored energy, the magnetizing current and the flux linkage, which were derived from the electrical equivalent circuit of the SFCL using single and double HTSC elements, were calculated from the voltages and the current measured in the short-circuit tests. Through the comparative analysis on the magnetization characteristics and the stored energy for SFCL using sing and double HTSC elements, the magnetically coupled SFCL using double HTSC elements was shown to be more effective than the SFCL using single HTSC element from the point of view of the magnetic saturation.
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Analysis on Current Limiting and Magnetizing Characteristics Due to Winding Locations of Superconducting Fault Current Limiter Using E-I Core
Bo-hee Kim, Sang-jae Choi, Sung-hun Lim
J Electr Electron Mater 2017;30(2):106-110.   Published online February 1, 2017
This paper compared current limiting characteristics of superconducting fault current limiter (SFCL) using E-I core due to the location of windings. Since E-I core has three legs and two magnetic paths, the current limiting characteristics of SFCL were expected to be affected by the installation location of windings, either center leg or right/left leg. To analyze its characteristics, the electrical equivalent circuit of the SFCL were derived and the electromagnetic analysis for the SFCL with the designed structure were performed. From the short-circuit tests, the hysteresis curve and the voltage-current trajectory of the SFCL due to the installation location of windings were extracted and compared each other. The SFCL with windings in the center leg of E-I core was shown to be larger magnetizing inductance compared to the one with windings in the right or left leg of E-I, which was analyzed from the hysteresis curve. In addition, larger decreased fault current right after the fault occurrence in the SFCL with windings in the center leg of E-I core was confirmed than the SFCL with windings in the right or left leg of E-I.
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Analysis on Fault Current Limiting Characteristics of Flux-Lock Type SFCL Using Magnetic Flux Application Circuit
Ju-chan Go, Seung-taek Lim, Sung-hun Lima
J Electr Electron Mater 2017;30(1):37-41.   Published online January 1, 2017
In this paper, the fault current limiting characteristics of the flux-lock type SFCL (superconducting fault current limiter) using magnetic application circuit were analyzed. The flux-lock type SFCL has the structure to install the magnetic application circuit, which can increase the resistance of HTSC (high-TC superconducting element comprising) the SFCL. To analyze the fault current limiting effect of the flux-lock type SFCL through the magnetic flux application circuit, the flux-lock type SFCL either with the magnetic flux circuit or without the magnetic flux circuit was constructed and the fault current limiting characteristics of the SFCL were compared each other through the short-circuit tests.
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