• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.89-92
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• 2012

The effect of organic impurities on the electrical properties of a neat epoxy resin was studied. 0.05, 0.5 and 1.0 phr of iso-propyl alcohol (IPA) and methylene chloride (MC) mixture (50/50 wt%) were used as impurities. The current density, volume resistance and impedance characteristics of the epoxy/IPA/MC systems were measured with a high voltage source meter and broadband dielectric spectroscopy. Glass transition temperature (Tg) was measured by a differential scanning calorimetry (DSC) and it was found that Tg decreased slightly with increasing IPA/MC content. It was also found that Tg values of the epoxy systems with various IPA/MC contents were closely related to the current density, volume resistance and impedance characteristics.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.7
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• pp.601-606
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• 2016

In this paper, an energy harvester is developed that has advantages regarding piezoelectric noise minimization, mass production, and an easily available environmental energy source, electromagnetic induction, as well as low-frequency bandwidth and high amplitude. A process for fabricating a three-dimensional multilayered planar coil using micro-electro-mechanical systems (MEMS) on a flexible printed circuit board FPCB is introduced. Optimal shape and size were calculated via internal resistance and inductance, and a prototype was fabricated through the MEMS procedure while considering the possibility of mass production. Although the internal resistance matched the designed value, the electromotive force generated did not reach the intended amount. The main reason for the decrease in efficiency was the low area of coil outskirt exposed to the magnetic field while there was relative motion between the magnet and the coil.

• Design & Manufacturing
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• v.8 no.1
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• pp.35-39
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• 2014

Window roller housings are durable because high-quality source materials such as stainless steel is used in making them. After a series of precise structure analysis, their design is optimized. They are subject to repetitive driving tests of more 100,000 times, durability tests, impact resistance tests, corrosion tests and others. For a long time, gaps often occur in press molded products owing to serious squareness deformation and flatness deformation of them. Severe burrs in press molded products require frequent grinding, which leads to short life cycle and rough or unreliable movement of assembled roller housing, which, in turn, causes product defects. This study focuses on developing measures to resolve existing defects and to improve lifespan of dies by designing and making a window roller shearing die.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.123-127
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• 2003

For disseminating a ney IEC international standard of critical trmperature of NbTi,Nb$_3$Sn and Bi-2223 Composite Suterconductors, we develpted a measuring system and studied standardization of test method. The measuring system consisted of cryogenic reservoir, base plate, thermometer, voltmeter and current source. Various specimens of the Nbti, Nb$_3$Sn and Bi-2223 composite superconductors were tested using this system for measuring their critical temperatures. After measuring the resistance-temperature relation, the data were compensated with thermoelectric voltages for NbTi Nb$_3$Sn specimens. NbTi specimens showed 9.2 K ~ 9.5 K of transition temperature and Nb$_3$Sn specimen showed about 18 K. Bi-2223 specimens showed 104 K ~ 107 K of transition temperature.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.408-411
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• 2008

In this paper, a new DC ground fault detection system is proposed, which is suitable for photovoltaic power generation systems. The proposed ground fault systems is superposition of divide resistance and detection circuit. The proposed system has the characteristics of a simplified structure, reduced cost and volume compared with those of the conventional ground fault system for DC source. The operation principle of the proposed systems is described and verified by simulation result.

• 연구논문집
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• s.23
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• pp.109-120
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• 1993

A study on corrosion and adhesion properties of evaporated Zn-Cr films were conducted on steel strip by two-source evaporater. Corrosion resistance of Zn-Cr coated steel was evaluated by salt spray test in 5% NaCl. Adhesion property of Zn-Cr films on steel substrate was evaluated by tape test after $180^\circC$ bending. Adhesion was improved with increasing the Cr content and reached the maximum at the Cr content of 6 to 8wt%. Corrosion resistance was enhanced with increasing the Cr content and improved by rolling Zn-Cr coated specimen, as a post-treatment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.1054-1056
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• 2002

High temperature Kermal diffusion from $POCl_3$ source usually used for conventional process through put of a cell manufacturing line and potentially reduce cell efficiency through bulk like time degradation. To fabricate high efficiency solar cells with minimal thermal processing, spin-on-doping(SOD) technique can be employed to emitter diffusion of a silicon solar cell. A technique is presented to emitter doping of a mono-crystalline solar cell using spin-on doping (SOD). Moreover it is shown that the sheet resistance variation with RTA temperature and time fer mono-crystalline and multi-crystalline silicon samples. This novel SOD technique was successfully used to produces 11.3% efficiency l04mm by 104mm size mono-crystalline silicon solar cells.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.5
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• pp.409-415
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• 2007

For satisfying a recommended value of the quality factor which is one of the important elements in a filter design, a new design method of smoothing filter using an internal parameter of a homopolar generator is proposed. The method increases the efficiency and minimizes the size of the smoothing filter by removing the damping resistor. By considering the resonant frequency as well as the quality factor, the new method can improve the stability of the system which has high boosting converters with negative resistance characteristics.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1413-1415
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• 2005

The OTFT performance depends strongly on the interfacial properties between an organic semiconductor and ${\alpha}$ metal electrode. The contact resistance is critical to the current flow in the device. The contact resistance arises mainly from the Schottky barrier formation due to the work function difference between the semiconductor and electrodes. We doped pentacene/source-drain interfaces with $F_4TCNQ$ (2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane), resulting in p-doped region at the SD contacts, in order to solve this problem. We found that the mobility increased and the threshold voltage decreased.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.567-570
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• 1989

A constant V/F control system of voltage contrlled PWM inverter has a unstable operation of the low- speed and the light-load. In this paper, the authors propose stability control with idealized operation of induction motor by the neglect of primary leakage inductance and resistance. Also ldealized operation system is adopted voltage error, feed back impedance circuit, and increasing resistance from dead time of switching is compensated by the soft ware with u-processors. The proposed simulation of the idealized control method is proved at the low-speed operation for three phase induction motor.