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"HIL"

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Regular Paper

Study on OCP Optimization and EIS-Based SOH Estimation for LiFePO4 Battery Packs Under Motor Load Conditions
Woo-Geun Jung, Jae-Ha Ko, Keon-Sik Hong
J Electr Electron Mater 2026;39(4):407-417.   Published online July 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.4.11
This study proposes an optimization strategy for the over-current protection (OCP) parameters of a lithium iron phosphate (LiFePO₄, LFP) battery system used in electric golf carts operating under high motor-load conditions. Real-world hillclimbing tests were conducted under four clearly defined payload/passenger conditions to analyze the transient discharge-current pro-file, voltage sag, and cell-temperature response. The maximum discharge current reached -238.2 A under the 200 kg cargopayload and one-passenger condition, and the current interval exceeding 150 A lasted up to 27 s. The maximum instantaneous power was 11.05 kW. Thermal analysis showed that the cell-temperature rise was within 2°C and the maximum measured cell temperature was 22.3°C. Linear regression of voltage and current yielded R² = 0.9368 and dV/dI = 0.0126 Ω, which was used as the DC internalresistance estimate. Based on these quantitative results and the cell specification limit of 300 A continuous discharge, the OCP threshold was reviewed from 250 A to 280 A to improve driving continuity while remaining below the allowable continuous-discharge current. EIS-based SOH estimation and the AI-BMS variable protection logic are presented as an extension framework for reflecting temperature and aging effects in future OCP-setting decisions.
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Effects of Growth Plate Stimulation Machine on Height Change in Human Body
Choon-nam Cho, Jae-sin Myung
J Electr Electron Mater 2021;34(5):357-363.   Published online September 1, 2021
DOI: https://doi.org/10.4313/JKEM.2021.34.5.13
Recently, as interest in appearance has increased, various studies on treatment method for short stature are being conducted. In this study, the effect of growth plate stimulation on the height growth of children and adolescents was studied. As a result of pre- and post-analysis of the experimental group, it was confirmed that the difference in average height according to growth plate stimulation was relatively large. In addition, in the results of analyzing the effects of demographic factors on the height growth of the experimental group and the control group, weight showed the greatest influence on height growth among the demographic factors affecting the height growth of the experimental group. The effect on the height growth of the control group was found to have an effect in the order of age, weight, and father’s height. The difference in height changed post-mortem between the experimental group and the control group was 1.10 cm for 3 months, and the difference was the result of growth plate stimulation. It was confirmed that growth plate stimulation had a significant effect on the height change of children and adolescents, except for weight, which is a common factor of height change in the experimental and control groups. Therefore, it is expected that it can be used as a treatment method for short stature.
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Photoinduced Hydrophilicity of Heterogeneous TiO2/WO3 Double Layer Films
Ji Yong Oh, Byung Roh Lee, Hwa Min Kim, Chang Hyun Lee
J Electr Electron Mater 2015;28(11):715-720.   Published online November 1, 2015
The photoinduced hydrophilicity of TiO2/WO3 double layer films was fabricated by using a conventional rf-magnetron sputtering method. The photoinduced hydrophilic reaction of the TiO2 surface was enhanced by the presence of WO3 under the TiO2 layer by irradiation of a 10 W cylindrical fluorescent light bulb. However, when the TiO2 and WO3 layers were separated by an insulating layer, the surface did not appeared high hydrophilic,under the same light bulb. The enhanced photoinduced hydrophilic reaction can be explained by the charge transfer between TiO2 and WO3 layers. It was also demonstrated that visible light passing through the TiO2 layer could excite WO3. Thus, visible light can be used for the hydrophilic reaction in the present TiO2/WO3 system.
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Thin Films and Sensors : Photocatalyst Surface Properties of the Oxide Thin Films According to the Plasma Etching Process
Chang Hyun Lee, Sung Bo Seo, Ji Yong Oh, Ik Hyeon Jin, Sun Young Sohn, Hwa Min Kim
J Electr Electron Mater 2015;28(5):300-305.   Published online May 1, 2015
WO3, SiO2, and TiO2 films with hydrophilic property are deposited by rf-magnetron sputtering. Their wettability is strongly depends on the presence or absence of the oxygen plasma etching on the glass substrates. The TiO2 film of 50 nm-thick on the plasma etched glass shows a water contact angle (WCA) below 5o which means a super-hydrophilic surface. However, WCA values are gradually degraded when the films are exposed under atmosphere, especially WO3. In order to improve hydrophilic property, the degraded films can be again recovered by UV illumination for 10 sec using UV-light and the TiO2 film shows a super-hydrophilic surface about 3o.
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Characteristics of Hillock Formation in the Al-1%Si Film by the Effect of Ion Implantation and Substrate Temperature
Chang Auk Choi, Yong Bong Lee, Jeong Ho Kim
J Electr Electron Mater 2014;27(1):8-13.   Published online January 1, 2014
As packing density in integrated circuits increases, multilevel metallization process has beenwidely used. But hillock formed in the bottom layers of aluminum are well known to make interlayershort in multilevel metallization. In this study, the effects of ion implantation to the metal film anddeposition temperature on the hillock formation were investigated. The Al-1%Si thin film of 1 ㎛thickness was DC sputtered with substrate (SiO2/Si) temperature of 20℃, 200℃, and 400℃, respectively. Ar ions (1×1015 cm-2: 150 keV) and B ions (1×1015 cm-2, 30 keV, 150 keV) were implanted to the Al-Sithin film. The deposited films were evaluated by SEM, surface profiler and resistance measuring system. As a results, Ar implanting to Al-Si film is very effective to reduce hillock size in the metal depositiontemperature below than 200℃, and B implanting to an Al-Si film is effective to reduce hillock density inthe high temperature deposition conditions around 400℃. Line width less than 3 ㎛ was free of hillockafter alloying.
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Electroluminescent Properties of Organic Light-emitting Diodes Depending on the Thickness of CuPc Hole-injection Layer
Jung Bok Lee, Kyung Hwan Kim, Tae Wan Kim, Won Jae Lee
J Electr Electron Mater 2013;26(12):899-903.   Published online December 1, 2013
We investigated the luminescence properties of Alq3 in the device structure of ITO/CuPc/TPD/Alq3/Al. The CuPc as a hole-injection material and TPD as hole-transport material. Emission properties were measured by varying a layer thickness of CuPc (0 nm to 50 nm), which is the hole-injection layer. As a result, it was found that the hole injection occurs smoothly when the layer thickness was 20 nm among the thicknesses from 0 nm to 50 nm.
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Properties Characterization of the Hydrophilic Inorganic Film as Function of Coating Thickness
Yeun Ho Joung, Won Seok Choi, Yong Tak Shin, Min Ji Lee, Hee Kon Kim
J Electr Electron Mater 2013;26(6):425-428.   Published online June 1, 2013
In this paper, we present a novel hydrophilic coating material (Wellture Finetech, Korea) which can be utilized as a coating layer for anti-contamination for electrical and electronic system. The coating material was deposited on 4 inch silicon wafer with several different film thickness. The film thickness was controlled by spin coating speed. After curing of the film, we have scratched by permanent marker to check self-cleaning property of the film. Also we have executed several mechanical tests of the films. As the spin coating speed is increased, the film thickness was thickness was thinned from 230 nm to 125nm. Contact angle of the film lowered from 30° to 12° as the spin coating speed is increased from 700 to 2,500rpm. On permanent marker scratched film surface coated at 1,000 rpm. We have poured regular city water to investigate self cleaning property of the film. The scratches were gradually separated from the film surface due to super-hydrophilicity of the film. Hardness of coated film was 9H measured by ASTM D3363 method. And adhesion of all film was 5B tested by D3359 method. Also, to get exact hardness value of the film, we have utilized a nano-indenter. As spin speed is increased, the hardness of film was increased from 3 Gpa to 5 Gpa.
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Effect on the Electrical Characteristics of OLEDs Depending on Amorphous Fluoropolymer
Sang Min Shim, Hyun Suk Han, Yong Gil Kang, Weon Jong Kim, Jin Woong Hong
J Electr Electron Mater 2011;24(9):750-754.   Published online September 1, 2011
In this research, the electric characteristic of organic light-emitting diodes(OLEDs) was studied depending on thickness of amorphous fluoropolymer(Teflon-AF) which is the material of hole injection layer to improve electric characteristic of OLEDs. Sample composition was fabricated in double layer. The basic structure was fabricated by ITO/tris(8-hydroxyquinoline) aluminum (Alq3)/Al and the 2 layer was fabricated by ITO/2,2-Bistrifluoromethyl-4,5-Difluoro-1,3-Dioxole(Teflon-AF)/tris(8-hydro xyquinoline) aluminum (Alq3)/Al. The experiment was carried with variation of thickness of Teflon-AF at 1.0, 2.0, 2.5, 3.0 nm. The result showed when Teflon-AF thickness was 2.5 nm, the electric and optical characteristic were well performed. Moreover, when it was compared with Teflon-AF without materials, it was improved 15.1 times more on luminance, 12.7 times more on luminous efficiency and 12.1 times more on external quantum efficiency. Therefore, OLEDs element with optimum hole injection layer reduced energy barrier and driving voltage, and confirmed that it improved efficiency widely.
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Comparison between Acid and Heat Treatment for Capacity Enhancement of RuO2/MWNT Composite Electrode materials for Ultracapacitor
Yong Tae Kim
J Electr Electron Mater 2010;23(1):65-69.   Published online January 1, 2010
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Capacity Change of Supercapacitor by Surface Treatment of Carbon Nanotubes
Yong Tae Kim
J Electr Electron Mater 2009;22(6):532-536.   Published online June 1, 2009
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Dielectric Properties of Epoxy/Organically Modified Layered Silicate Nanocomposites
Jae Jun Park
J Electr Electron Mater 2008;21(2):188-193.   Published online February 1, 2008
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Hydrophilic Effect of the Polyimide by Atmospheric Low-temperature Plasma Treatment
J Electr Electron Mater 2005;18(2):148-152.   Published online February 1, 2005
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