• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.423-428
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• 2003

In a direct modulated semiconductor laser diode. the structural dependence of current blocking layers was studied in view of the leakage current reduction and the bandwidth expansion. To analyze the leakage current and the parasitic effects, the current-voltage derivation characteristics and the subtraction method were used, respectively. It was shown that the‘inin’type current blocking structure might be the best choice for the purpose of the static and dynamic characteristics.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.4
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• pp.357-362
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• 2010

Electricity can be directly generated from organic matter even wastewaters using a microbial fuel cell. To achieve high power in MFCs, finding factors decreasing activation and Ohmic losses is very important. In this study we determined activation loss at the anode and cathode and Ohmic loss using the current interruption technique in a H-type MFC. Activation loss at the cathode was four times higher that that of anode activation loss even if pt-coated carbon (0.5 $mg/cm^2$;10%Pt) was used as the cathode. Ohmic loss determined using current interruption technique (1146 ${\Omega}$) was almost same as the internal resistance (1167 ${\Omega}$) measured using AC impedance. The sum of activation losses at the anode and cathode was the same as the value of activation loss of the cell.

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.11-17
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• 1995

반절연 InP를 전류 차단층으로 사용하는 초고속 변조 Distributed Feedback (DFB) 레이저의 다이오드를 제작 하였다. Grating이 형성된 InP 기판에 유기금속 증착법 (MOVPE)을 사용하여 다중 양자 우물 구조 성장 시켜 메사구조를 연성 한후, 전류 차단층으로 반절연 InP를 성장 하였다. 제작된 레이저 다이오드는 평균 문턱전류 10 mA, 기울기효율 14%이며, 30mA 구동 전류에서 10GHz 이상의 3dB 대역폭 특성을 보였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.4
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• pp.353-358
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• 2013

The current interruption method is considered to be an efficient way of measuring the resistance of a fuel cell. In this study, the ohmic area specific resistances (ASRs) of polymer electrolyte fuel cells with different types of bipolar plates were evaluated using the current interruption method. The ohmic ASRs of both a fuel cell with graphite bipolar plates and a fuel cell with graphite foil-based assembled bipolar plates decreased as the current density increased. On the other hand, with increasing cell temperature, the ohmic ASRs of a fuel cell with graphite bipolar plates were decreased by a reduction in the proton transport resistance through the membrane, and the ohmic ASRs of a fuel cell with graphite foil-based assembled bipolar plates were increased by the differences in thermal expansion between different components of the bipolar plates.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.9
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• pp.64-72
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• 1998

In this paper, the design of a current integrator for low-voltage, low-power, and high frequency applications using complementary high swing cascode current-mirror is presented. The proposed integrator decreases output current errors due to non-zero input resistance and non-infinite output resistance of the simple current integrator. As a design example, the 3rd order Butterworth lowpass filter is designed by a leapfrog method. Also, we apply the predistortion design method to reduce the magnitude distortion which occurs at a cutoff frequency by the undesirable phase shift of a lossless current integrator. The designed current-mode filter is simulated and examined by SPICE using 0.8$\mu\textrm{m}$ CMOS n-well process parameters. The simulation results show 20MHz cutoff frequency and 615㎼ power dissipation with a 2V power supply. And the cutoff frequency of the filters can be easily changed by the DC bias current.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.02a
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• pp.47-47
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• 1999

• Journal of the Korean Vacuum Society
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• v.15 no.3
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• pp.273-279
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• 2006

This study explored the possibility of porous Si (PS) formed by indirect electrode anodization used for effective isolation material for radio frequency integrated circuits (RFIC). We investigated the effect of current density and reaction time on the porosity size and depth, and X-ray diffraction of bulk Si and porous Si to evaluate the change in lattice parameter. Porosity size and depth usually increases with an increase in the current density and reaction time. PS increases the lattice parameter of Si compared to the bulk Si which causes the compressive stress of around 8 MPa. PS formed by the method is believed to be suitable for isolation material for RFIC because it is simple process as well as good compatibility to Si VLSI process.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.838_839
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• 2009

차단기는 전력계통에서 고장이 발생한 경우, 고장전류가 퍼져나가는 것을 방지하고 고장전류에 의해 계통에 연결된 다른 기기들이 손상을 입는 것을 방지하는 전력기기이다. 그 중 진공 차단기는 친환경성과 우수한 절연특성으로 배전급 중.저압용 차단기로 널리 사용되고 있다. 차단기는 크게 조작부와 차단부로 구분되는데 진공 차단기의 조작부 메커니즘은 스프링 구동방식과 영구자석형 마그네틱 액츄에이터(PMA)를 사용하여 구동하는 방식으로 나뉜다. 본 논문에서는 진공차단기의 조작부인 영구자석형 마그네틱 액츄에이터(PMA)의 개방.투입 유지력과 동작특성을 유한요소법을 이용하여 해석하였다. 정밀한 해석을 위해 물질의 비선형성을 고려하였으며, 외부회로와 결합한 전자계 해석을 하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1550-1551
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• 2011

본 논문은 가정에서 사용하는 중 저압용 차단기의 차단 능력을 향상시키기 위한 방법에 초점을 두었다. MCCB의 차단 능력은 MCCB내부 부품들의 재료나 형상 그리고 배열 등 여러 요소에의해 결정된다. 특히 본 논문에서는 MCCB 그리드의 형상을 변화하여 소호시간을 단축하는 방법을 제안하였다. 사고에 의해 차단기가 작동하게 되면 차단기 내부 접점에서 Arc가 발생하게 된다. 이때 발생된 Arc에의한 2차 사고를 방지하기위해, Arc를 빠른 시간에 소호시켜야한다. Arc가 발생하게 되면 Arc내부는 도체처럼 전류가 흐르게 되는데 이 전류에 의해 소호부의 그리드를 따라 자속이 형성된다. 그리드의 형상에 따라 Arc 기둥 주변에 불균형적인 자속이 유도되고 이 불균형한 자속에 의해 Arc 주변에는 불균형한 로렌츠힘이 발생하여 일정 방향으로 힘이 작용하게 된다. 이때 발생한 로렌츠힘 에의해 Arc 기둥은 그리드 방향으로 소호된다. 분석을 위해 유한요소법을 이용한 시뮬레이션을 사용하였고 그리드 형상 변화를 통해 일정방향으로 로렌츠힘이 변화 전보다 증가한 결과를 얻었다. 본 논문의 내용에 추가로 그리드 내부에서 자속의 이동을 효율적으로 전달하기위한 방법을 연구하면 더 큰 로렌츠힘을 얻어 소호시간을 단축시킬 수 있을 것으로 사료된다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.4
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• pp.28-34
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• 2000

In this paper, a continuous-time filter for low voltage and high frequency applications using fully-balanced current integrators is presented. As the balanced structure of integrator circuits, the designed filter has improved noise characteristics and wide dynamic range since even-order harmonics are cancelled and the input signal range is doubled. Using complementary current mirrors, bias circuits are simplified and the cutoff frequency of filters can be controlled easily by a single DC bias current. As a design example, the 3rd-order lowpass Butterworth filter with a leapfrog realization is designed. The designed fully-balanced current-mode filter is simulated and examined by SPICE using 0.65${\mu}{\textrm}{m}$ CMOS n-well process parameters. The simulation results show 50MHz cutoff frequency, 69㏈ dynamic range with 1% total harmonic distortion(THD), and 4㎽ power dissipation with a 3V supply voltage.