• 한국정보처리학회논문지
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• 제7권4호
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• pp.1246-1264
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• 2000

An input-output buffering switch operates in either of tow different cell loss modes; Backpressure mode and Queueloss mode. In the previous studies, the Backpressrue mode is more effective at low traffic loads, and the Queueloss mode performs better at high traffic. We propose a new operation mode, called Hybrid mode, which adopts the advantages of he Backpressure and the Queueloss mode. Backpressure and Queueloss modes are distinguished from whether a cell loss occurs at the output buffer or not when output buffer overflows, irrespective of input buffer status. In order to simply combine Backpressure and Queueloss mode, the change of input traffic load must be measured. However, in the Hybrid mode, simply both of the input and output buffer overflow and checked out to determine the cell discard. The performance of the Hybrid mode is compared with those of the Backpressure and the Queueloss mode under random and bursty traffic. This paper show that the Hybrid mode always gives the best performance results for most ranges of load values.

• E2M - 전기 전자와 첨단 소재
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• 제14권12호
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• pp.3-6
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• 2001

In common globular proteins, the native form is n its most stable state. However, the native form of inhibitory serpins (serine protease inhibitors) and some viral membrane fusion proteins is in a metastable state. Metastability in these proteins is critical to their biological functions. Our previous studies revealed that unusual interactions, such as side-chain overpacking, buried polar groups, surface hydrophobic pockets, ad internal cavities are the structural basis of the native metastability. To understand the mechanism by which these structural defects regulate protein functions, cavity-filling mutations of $\alpha$1-antitrypsin, a prototype serpin, were characterized. Increasing conformational stability is correlated with decreasing inhibitory activity. Moreover, the activity loss appears to correlate with the decrease in the rate of the conformational switch during complex formation with a target protease. We also increased the stability of $\alpha$1-antitrypsin greatly via combining various stabilizing single amino acid substitutions that were distributed throughout the molecule. The results showed that a substantial increase of stability, over 13 kcal/mol, affected the inhibitory activity with a correlation of 11% activity loss per kcal/mol. The results strongly suggest that the native metastability of proteins is indeed a structural design that regulates protein functions and that the native strain of $\alpha$1-antitrypsin distributed throughout the molecule regulates the inhibitory function in a concerted manner.

• 한국항공우주학회지
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• 제33권4호
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• pp.41-46
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• 2005

본 연구에서는 고 전력의 RF 신호용 직접 접촉식 스위치에서 문제가 되고 있는 접촉부위에서의 미소용접에 의한 점착 현상을 감소시키기 위해, 고 융점 금속인 텅스텐(W)과 몰리브덴(Mo)을 스위치 접촉 부위에 코팅하여 스위치의 성능을 분석하였다. 스위치의 삽입손실과 신호격리도, 전력 손실 등의 변화를 네트워크 분석기, 전력 측정기 등을 통하여 측정하였다. 측정결과로부터 RF 신호 전송에 있어서 낮은 입력 전력에서는 고융점 금속이 금(Au)보다 접촉저항이 더 크지만 입력 전력이 커지면 비교적 낮은 비저항의 고융점 금속을 사용하는 것이 고전력 전송 및 수명 연장에 있어서 유리함을 밝혀냈다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.3-6
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• 2001

In common globular proteins, the native form is in its most stable state. However, the native form of inhibitory serpins (serine protease inhibitors) and some viral membrane fusion proteins is in a metastable state. Metastability in these Proteins is critical to their biological functions. Our previous studies revealed that unusual interactions, such as side-chain overpacking, buried polar groups, surface hydrophobic pockets, and internal cavities are the structural basis of the native metastability. To understand the mechanism by which these structural defects regulate protein functions, cavity-filling mutations of ${\alpha}$1-antitrypsin, a prototype serpin, were characterized. Increasing conformational stability is correlated with decreasing inhibitory activity. Moreover, the activity loss appears to correlate with the decrease in the rate of the conformational switch during complex formation with a target protease. We also increased the stability of ${\alpha}$1-antitrypsin greatly via combining various stabilizing single amino acid substitutions that were distributed throughout the molecule. The results showed that a substantial increase of stability, over 13 kcal/mol, affected the inhibitory activity with a correlation of 11% activity loss per kcal/mol. The results strongly suggest that the native metastability of proteins is indeed a structural design that regulates protein functions and that the native strain of e 1-antitrypsin distributed throughout the molecule regulates the inhibitory function in a concerted manner.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1148-1150
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• 2003

Power conversion system must be increased switching frequency in order to achieve a small size, a light weight and a low noise. However, the switches of converter are subjected to high switching power losses and switching stresses. As a result of those, the power system brings on a low efficiency. To improved these, a large number of soft switching topologies included a resonant circuit has been prosed. But these circuits increase number of switch in circuit and complicate sequence of switching operation. In this paper, the authors propose a high power factor and high efficiency DC-DC converter using single-pulse soft switching by partial resonant switching node. The switching devices in a prosed circuit are operated with soft switching by the partial resonant method, that is, Partial Resonant Switch Mode Power Converter. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. The result is that the switching loss is very low and the efficiency of system is high. Also the proposed converter is deemed the most suitable for high power applications where the power switching devices are used. Some simulative results on computer results are included to confirm the validity of the analytical results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.391-393
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• 2008

A modified boost converter with magnetic coupling is presented to reduce the reverse recovery loss while maintaining low conduction loss of the rectifiers. By utilizing a coupled inductor and a set of diodes, the current passing the boost rectifier is transferred to an auxiliary loop before turn-off, allowing low di/dt for reduced recovery loss. Moreover, the boost inductor is brought inside the bridge rectifier to reduce conduction loss by decreasing the number of conducting diodes during switch turn-off. Experimental results of a 500W prototype are provided to verify the increase in efficiency and validity of the proposed converter.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.551-552
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• 2008

This paper presets a results of frequency response in variation of wire bonding length. A gold ball bonding is used as a wire bonding process, and a DPDT(double pole double thru) switch is adapted as a device for test. Wire length is ranged from 442um to 833um and a measured frequency range is from 1 GHz to 6 GHz. Little difference are measured in insertion loss and return loss depending on wire length. Measured S21 and S11 are -0.58 dB and -17.7 dB, respectively. S21 insertion loss is rising up and S11 insertion loss is falling down as the frequency is increased.

• Journal of Power Electronics
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• 제7권1호
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• pp.55-63
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• 2007

This paper proposes a simple unity power factor zero-voltage-transition (ZVT) pulse-width-modulated (PWM) single-phase rectifier, which features reduced switching and conduction losses. The switching loss reduction is achieved by a simple auxiliary commutation circuit, and the conduction loss reduction is achieved by employing a single-stage converter, rather than a typical double-stage converter comprising of a front-end rectifier and a boost rectifier. Furthermore, thanks to good features such as a simple PWM control at constant frequency, low switch stress, low Var rating of commutation circuits, and simple power circuit structure, it is suitable for high power applications. The principles of operation are explained in detail, and a major characteristics analysis and the experimental results of the new converter are also included in this paper.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.501-507
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• 2014

This paper describes the improvement in converter efficiency by reducing the switching loss and by recovering the snubber stored energy. A capacitive based passive regenerative snubber circuit is modeled for a dc-dc boost converter. The proposed snubber is mainly used to reduce the turn-off loss of the main switch. The energy recovery process and the turn-off loss depends on the size of the snubber capacitance; therefore, the conventional and the proposed converters are designed for high and low input voltage conditions with different sizes of the snubber capacitance. Based on the results obtained, the snubber capacitors are classified as small, normal and large snubbers. The Matlab simulation results obtained are presented.

• 조명전기설비학회논문지
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• 제18권2호
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• pp.75-82
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• 2004

본 논문에서 액티브 스너버 회로를 가진 영전압 변환 펄스 폭 변조(ZVT-PWM) 컨버터를 제안하였다. 제안된 컨버터는 경부하 상태에서도 동작하며, 영전압 스위칭과 영전류 스위칭 부근에서 온-오프 되며, 주 스위치와 주다이오드에 전압과 전류의 스트레스가 추가적으로 발생하지 않는다. 그리고 보조 스위치와 보조 다이오드의 전압과 전류 허용 레벨을 제시하였다. 제안된 750[W], 80[KHz] PWM 부스터 컨버터는 전 출력 전력에서 소프트 스위칭 컨버터를 적용하여 실행한 결과 주 스위치에서의 손실은 하드 스위칭과 비교해서 약 27[%], 전체 회로 손실은 약 36[%] 저감되었으며, 전체 효율은 기존의 컨버터보다 보다 6{%] 정도 향상됨을 확인하였다.