The Hall factor in a quantum well structure with X or L-type indirect conduction valleys is calculated for various strain conditions. The two-dimentsional constant energy of occupied valleys are proven to be identical. As a result the Hall factor depends on the direction of occupied valleys to the growth direction, regardless of the number of occupied valleys. This work is widely applicable to the two-dimensional structure with indirect conduction minima for any growth direction and under different strain conditions.

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.

PTFE composites for use of microwave substrate were fabricated by impregnation and heat treatment fabrication with glass fabric. This study shows dielectric properties such as dielectric constant and loss can be controlled by thickness of PTFE composite with of pressure condition in heating press process. The dielectric constant of the PTFE composites has decreasing tendency as given higher pressure condition. The dielectric loss has similar result too. Especially, the case of the dielectric loss was affected by the condition of pressure at heating press and had the best performance under 3 MPa. In order to see the reason why thickness conditions make different, their microstructures were also observed.

With polymer properties and ceramic volume fraction as design variables, the optimal structure of 1-3 piezocomposites has been determined to maximize the thickness mode electromechanical coupling factor. When the piezocomposite vibrates in a thickeness mode, inter-pillar resonant modes are likely to occur between lattice-structured piezoceramic pillars and polymer matrix, which significantly deteriorates the performance of the piezocomposite. In this work, work, a new method to design the structure of the 1-3 type piezocomposite is proposed to maximize the thickness mode electromechanical coupling factor while preventing the occurrence of the inter- pillar modes. Genetic algorithm was used for the optimal design, and the finite element analysis method was used for the analysis of the inter-pillar mode.

ZnO nanowires on the a-, c- and m-plane oriented 4H-SiC substrates were grown by using a high temperature tube furnace, Ti/Au electrodes were deposited on ZnO nanowires and a-, c- and m-plane 4H-SiC substrates, respectively. The shape and density of the ZnO nanowires were inestigated by field emission scanning electron microscope. It was found that the growth direction of nanowires depends strongly on growth parameters such as growth temperature and pressure. In this work, The sensitivity of nanowires formed a-, c- and m-plane oriented 4H-SiC gas sensor was measured at 300℃ with CO gas concentration of 80%. The nanowires grown on a-plane oriented 4H-SiC show improved performance than those on c- and m-plane oriented 4H-SiC due to the increased density of nanowire on a plane 4H-SiC.

Growth mechanism of GS-MBE (Gas source-Molecular Beam Epitaxy) has been investigated. We observed that the growth rate of GaN films is changing from 520 nm/h to 440nm/h by the variation of V/III ratio under nitrogrn-rich growth condition. It was explained the amount of hydrogen on the growth front varies by the ammonia flow, and gallium hydrides are generated on the surface by a reaction of hydrogen and gallium, resultantly the amount of gallium supplying is changing along with the NH3 flow. Reflection high energy electron diffraction (RHEED) observation was used to confirm the N-rich condition. The crystal quality of GaN was estimated by photoluminescence (PL) and X-ray diffraction (XRD).

To study emission properties of white phosphorescent organic light emitting devices (PHOLEDs), we fabricated white PHOLEDs of ITO (150 nm) / NPB(30 nm) / TcTa(10 nm) / mCP(7.5 nm) / light-emitting layer(25 nm) / UGH3(5 nm) / Bphen(50 nm) / LiF(0.5nm) / Al(200 NM) structure. The total thickness of light-emitting layer with co-doping and blue-doping/ co-doping using a host-dopant system was 25 nm and the dopant of blue and red was FIrpic and Bt2Ir(acac) in UGH3 as host. respectively. The OLED characteristics were changed with position and thickness of doping layer and co-doping layer as light-emitting layer and the best performance seemed in structure of blue-doping(5 nm)/co-doping(20 nm) later. The white PHOLEDs showed the maximum current density of 34.5 mA /cm², maximum brightness of 5,731 cd/ m², maximum current efficiency of 34.8 cd/A, maximum power efficiency of 21.6lm/w, maximum quantum effiency of 15.6%, and a Commission International de L`Eclairage (CIE) coordinate of (0.367, 0.436) at 1,000 cd/m².

In this paper a novel method based on geometrical optics proposed to calculate the optical characteristics of an electric field driven liquid crystal (ELC) lens. For an optimally designed ELC lens, effective refractive index is calculated and then ray tracing is carried out using Huygens′ principle. From the results, the intensity distribution at the optimum viewing distance (OVD) is obtained. To confirm the validity of our work, the result is compared with that calculated by the extended Jones matrix method (EJMM). As a result, it turns out that the novel method provides more simple and rigorous simulation results than the EJMM.

In this paper, we analyzed the effects of doctoring process on the patterns of Ag in gravure off-set printing. The parameters of doctoring process were the angle and the pressure, which was represented by the depth of movement to the gravure roll, of doctor blade to the surface of gravure roll, and the angle of patterns engraved on the gravure roll to doctor blade moving direction. The proper parameters were extracted for the fine patterns and they were 15 mm for the pressure, 60° for the blade angle. And the angle of patterns with respect to blade movement should be less than 40° for the best results. The gravure off-set printing with the above parameters was carried out print gate electrodes and scan bus lines of OTFT-backplane for e-paper. The line width of 50㎛ was successfully obtained. The thickness of electrodes was 2.5㎛and the surface roughness was 0.65㎛ and sheet resistance was 15.8 Ω/□.

In this paper, we analyzed the effects of the number of TIPS-pentacene droplets and also the substrate temperature on the performance of OTFTs As the number of the droplets increased, the mobility increased and reached the perk value and then reduced at all temperatures. The peak mobility was 0.14 ± 0.03 cm²/V sec at 3 droplets and 41℃, 0.19 ± 0.02 cm²/V.sec at 4 droplets and 46℃,and 0.35 ± 0.10 cm²/V sec at 7 droplets and 51℃. The reason of existence of peak mobility can be found in matching the evaporation of solvent with the velocity of crystal formation. When two parameters were properly matched, the mobility produced the highest.

This paper carried out the comparative analysis on ground impedance of a carbon block and a copper rod. Two types of grounding electrode were compared; a carbon block (L: 1 m, ф : 245 mm)buried at depth of 0.8m and a three-linked copper rod (L : 1 m, : ф : 10 mm) of equilateral triangles with 1 m spacing. Ground impedance depending on applied current was evaluated by the application of a sine wave current with 60 Hz~3.5 MHz, fast-rise pulse with rising time of 200 ns, a standard lightning impulse of 8/20 ㎲ and a 600 Hz square wave. Ground impedance for both electrodes were almost the value below 100 KHz, and increased rapidly afterwards. The maximum ground impedance appeared 400 Ω at around 1.5 MHz. Ground impedance of the block was lower at the square wave and was higher at fast-rise pulse that of the copper rod. Also, impedance as ages showed no difference for the 8 months. From the results, it is likely that ground performance for both electrodes shows no difference against commercial frequency and lighting impulse current, while the copper rod shows better performance against fast-rise pulse with rise-time of a few hundred ns.

Diameter controlled carbon nanotubes (CNTs) were grown using surface modified iron nano-particle catalysts with aminpropyltriethoxysilane (ASP). Iron nano-particles were synthesized by thermal decomposition of iron pentacarbonyl-oleic acid complex. Subsequently, APS modification was done using the iron nano-particles synthesized. Agglomeration of the iron nano-particles during the CNT growth process was dffectively prevented by the surface modification of nano-particles with the ASP. Plays as a linker material between Fe nano-particles and SiO₂ substrate resulting in blocking the migration of nano-particles. ASP also formed siliceous material covering iron nano-particles that prevented agglomeration of iron nano- particles at the early stages of the CNT growth. Therefore we could obtain the diameter controlled CNTs by blocking agglomeration of iron nano-particles.

The new recycling technology for aged aluminum wires in overhead conductor have been carried out. We are attempting to develop remanufacturing method for them for more effective way of recycling in stead of its conventional remelting process. The drawing process of aged aluminum wires play a role in remanufacture process. Drawing process was performed under lubricant. The speed of drawing was between 500 m/min and 1,000 m/min. These machines have 11 or 12 dies house for breakedown of the feedstock. of the die is tungsten carbide and they have generally 25% reduction ratio. The paper investigates the mechanical properties during drawing process of aged aluminum wire. The results of tensile tests and microscopic analysis were discussed to underscore the hardening features of drawing of aluminum wire. Various graphs are presented accompanied by discussion about their relevance on the process.

Current limiting diode (CLD) was fabricated using junction field effect transistor (JFET) structured two small cells and eight large cells. Two small cells and eight large cells were connected in parallel and the obtained constant current was 110 mA. The application of CLD in each of the parallel circuits on chip on board (COB) type LED lighting source, could significantly reduce the current deviation within the parallel circuits. The applications of CLD on AC power small lighting source, battery power low voltage parallel lighting source and AC flat lighting source were investigated.

LED lighting is sensitive because made by semiconductor. So it has been researched about radiation of heat technologies for long time. In addition, measurement and assessment a radiation of heat also conducted. It is necessary to get a date of accuracy temperature on the board after LED driven for measuring Junction temperature of LED Lighting. For this research we use 5 chip which is 4 W power on top of LED lighting board made by aluminum. Thermal camera effects to emissivity depending on material and property of surface in LED board because it determines thermal energy which emitted from material surface. It is not only thermal camera has not a standard about emissivity. It has an error of temperature when emissivity was measured by thermal camera. We confirmed that emissivity and reflected temperature depending on color and quality of surface throughout experiment.