• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.260-262
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• 2002

This study presents a AC electric railway system model using PSCAD/EMTDC. Ver.3.08 for circuit analysis and fault studies. This system model made by PSCAD/EMTDC is composed of feeder, contact line, rails, Scott-transformer, Auto-transformer. This model is based on four-port network which is an extension of two-port network theory. In order to verify the proposed model, each voltage of feeder-rail, contact line-rail and feeder-contact line is measured and fault studies are also simulated.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권11호
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• pp.546-550
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• 2002

In this paper, Heterojunction phototransistors(HPT's) with an optically transparent ITO emitter contacts were fabricated. The ITO ohmic contacts were realized by employing thin imdium layer between the ITO and $n^+$-InP layers. The ITO contact was annealed at $250^{\circ}C$. The specific contact resistance of about $6.6{\times}10^{-4}{\Omega}cm^2$ was measured by use of the transmission line model (TLM). Heterojunction bipolar transistors (HBTs) having the same device layout were fabricated to compare with HPTs. The DC characteristics of the InP/InGaAs HPT showed the similar electrical characteristics of the HBT. Emitter contact resistance($R_E$) of about $6.4{\Omega}$ was extracted, which was very similar to that of the HBT. The optical characteristics of HPT's were generated by illuminating the device with light from $1.3{\mu}m$ light. It showed that HPT's can be controlled optically.

• 전기의세계
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• 제18권6호
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• pp.23-32
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• 1969

The thesis has derived the formulas and computational algorithms useful for predicting and constraining the potential rises on the neutral line in 3-phase, 4-wire distribution line systems in the case of contact faults and single-line grounding faults. In addition it has suggested economically optimal designing conditions herewith of the distribution line systems in conduction with the potential restraining cost functions.

• 전기학회논문지
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• 제57권8호
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• pp.1416-1421
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• 2008

A 10 dB branch line hybrid coupler included with defected ground structure (DGS) is proposed. In this contribution, a contact between the grounded metal housing and DGS is avoided, which has been a serious problem in applying DGS to high frequency circuits. An isolation between the metal housing and the DGS pattern is provided by inserting additional substrate between DGS and the metal package. Therefore, it is possible to design branch line hybrid couplers having highly asymmetric power dividing ratio using these DGS structure, which is demonstrated in this paper. The designed and fabricated branch line hybrid coupler using DGS is well packaged in a metal housing without touching the ground metal directly. The measurement is performed under realistic practical operating situations because it is packaged in a metal housing. The measured performances of the fabricated 10dB coupler shows a 1:9 asymmetric power dividing ratio at output ports, as predicted. In addition, the measured performances in terms of matching, isolation, and phase difference are in excellent agreement with the simulated characteristics.

• 센서학회지
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• 제15권6호
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• pp.386-390
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• 2006

This paper describes the ohmic contact formation of polycrystalline 3C-SiC films deposited on thermally grown Si wafers. In this work, a TiW (titanium tungsten) film as a contact material was deposited by RF magnetron sputter and annealed with the vacuum process. The specific contact resistance (${\rho}_{c}$) of the TiW contact was measured by using the C-TLM (circular transmission line method). The contact phase and interfacial reaction between TiW and 3C-SiC at high-temperature as also analyzed by XRD (X-ray diffraction) and SEM (scanning electron microscope). All of the samples didn't show cracks of the TiW film and any interfacial reaction after annealing. Especially, when the sample was annealed at $800^{\circ}$ for 30 min., the lowest contact resistivity of $2.90{\times}10{\Omega}cm^{2}$ was obtained due to the improved interfacial adhesion. Therefore, the good ohmic contact of polycrystalline 3C-SiC films using the TiW film is very suitable for high-temperature MEMS applications.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.724-729
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• 2005

Winter weather condition can cause icing and ice coats on 25 kV overhead contact wire. This generates shocks at the mechanical interface of the collecting strips of the pantograph and the contact wire and extra electrical resistance, which may affect quality of current collection at the contact wire / collecting strips of pantograph interface. De-icing operations should he performed just before train operation to avoid the formation of another ice layer. Thus, the work in this paper is investigation and analysis of de-icing system which could be applied to the electric car line of railways.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.551-555
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• 2010

Electrowetting is a versatile tool to handle tiny droplets and forms a backbone of digital microfluidics. Numerical analysis is necessary to fully understand the dynamics of electrowetting, especially in designing electrowetting-based devices, such as liquid lenses and reflective displays. We developed a numerical method to analyze the general contact-line problems, incorporating dynamic contact angle models. The method is based on the conservative level set method to capture the interface of two fluids without loss of mass. We applied the method to the analysis of spreading process of a sessile droplet for step input voltages and oscillation of the droplet for alternating input voltages in electrowetting. The result was compared with experimental data. It is shown that contact line friction significantly affects the contact line motion and the oscillation amplitude. The pinning process of contact line was well represented by including the hysteresis effect in the contact angle models. In level set method, in the mean time, material properties are made to change smoothly across an interface of two materials with different properties by introducing an interpolation or smoothing scheme. So far, the weighted arithmetic mean (WAM) method has been exclusively adopted in level set method, without complete assessment for its validity. We viscosity, thermal conductivity, electrical conductivity, and permittivity, can be an alternative. I.e., the WHM gives more accurate results than the WAM method in certain circumstances. The interpolation scheme should be selected considering various characteristics including type of property, ratio of property of two fluids, geometry of interface, and so on.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권9호
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• pp.371-377
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• 2003

We perform the physical analysis such that Si/W composition ratios and phosphorus distribution change in the W/S $i_{x}$ thin films according to phosphorus concentration of polysilicon and W $F_{6}$ flow rate for the formation of WS $i_{x}$ polycide used as a gate electrode. We report that these physical characteristics have effects on the contact resistance between word line and bit line in DRAM devices. RBS measurements show that for the samples having phosphorus concentrations of 4.75 and 6.0${\times}$10$^{2-}$ atoms/㎤ in polysilicon, by applying W $F_{6}$ flow rates decreases from 4.5 to 3.5 sccm, Si/W composition ratio has increases to 2.05∼2.24 and 2.01∼2.19, respectively. SIMS analysis give that phosphorus concentration of polysilicon for both samples have decreases after annealing, but phosphorus concentration of WS $i_{x}$ thin film has increases by applying W $F_{6}$ flow rates decreases from 4.5 to 3.5 sccm. The contact resistance between word line and bit line in the sample with phosphorus concentration of 6.0 ${\times}$ 10$^{20}$ atoms/㎤ in polysilicon is lower than the sample with 4.75 ${\times}$ 10$^{20}$ atoms/㎤ After applying W $F_{6}$ flow rates decreases from 4.5 to 3.5 sccm, the contact resistance has been improved dramatically from 10.1 to 2.3 $\mu$ $\Omega$-$\textrm{cm}^2$.

• 융합신호처리학회논문지
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• 제13권4호
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• pp.201-206
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• 2012

간접접촉 심전도 측정(Indirect-Contact ECG)은 일상생활에서의 무구속 무자각 측정에 적합한 심전도 측정 방법이다. 본 연구는, 간접접촉 심전도 측정에서 크게 관측되는 60Hz 전원선 잡음을 줄이기 위한 새로운 방법으로, 공통모드 구동 차폐 방식을 제안하였다. 공통 모드 구동 차폐 방식은, 간접 접촉 심전도에서 사용되는 용량성 결합 능동 전극(Capacitive coupling active electrode)을 둘러싼 전기적 차폐(electric shield)의 전압을 공통 모드 전압과 동일하게 유지하는 방법이다. 이 방법은 공통모드 전압의 크기는 그대로 유지하지만, 의복 임피던스 차에 의한 공통모드 전압의 차동 모드 전환에 의한 잡음은 효과적으로 줄일 수 있다. 따라서 두 전극 사이의 의복의 임피던스 차이가 커서 공통 모드 전원 잡음이 심각한 간접 접촉 심전도 측정에서, 효과적으로 공통 모드 잡음을 줄일 수 있다. 실제 간접 접촉 심전도 측정에 제안된 방법을 적용한 결과로 이론적 예상보다는 60Hz 잡음 감소비가 적었지만, 60Hz 잡음이 크게 줄어드는 것을 확인할 수 있었다. 특히 의복 임피던스 차가 크게 발생하는 경우, 예상대로 잡음 감소비가 커짐을 볼 수 있었다. 제안된 방법은 접지 특성이 좋지 않은 측정 조건에서 전원 잡음을 줄이는데 유용할 것으로 기대된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.834-837
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• 2003

In this study, Ohmic contacts make on 3C-SiC using TiN. Ohmic contact resistivity of TiN/3C-SiC was evaluated. Specific contact resistance was calculated by Circular-TLM(transmission line model) method and physics properties were measured using XRD, SEM, respectively. TiN contact is stable at high temperatures and a good diffusion barrier material. The TiN/3C-SiC contacts are thermally stable to annealing temperatures up to $1000^{\circ}C$. The TiN thin-film depostied on 3C-SiC substraes have good electrical properties. Therefore, the TiN/3C-SiC contact can be usefully applied for high-temperature MEMS applications over $500^{\circ}C$.