• 전자공학회논문지
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• 제53권6호
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• pp.55-66
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• 2016

파워 게이팅은 반도체 칩의 누설전류(leakage current)를 감소시키는 데 효과적인 기술로 알려져 있으며, 전원 차단용 파워게이팅 셀 (power-gating cell, PGC)에서의 IR drop 증가로 인한 성능 및 신뢰성 저하에 대해 많은 연구가 이루어져왔다. 그러나 최신 공정에서는 트랜지스터 사이즈 감소 추세에도 불구하고 금속 배선의 스케일링이 제한됨에 따라, IR drop에 견고한 파워 게이팅 설계 시 셀 배치와 금속 배선 면적을 고려한 새로운 접근 방식이 필요하다. 본 논문에서는 셀 점유율(cell utilization)과 소모 전류에 근거한 로직 셀 배치 기법을 통해 PGC 면적 및 IR drop을 개선한 파워 게이팅 설계 방법을 제안한다. 28nm 공정으로 제조된 스마트폰용 어플리케이션 프로세서(Application processor, AP) 내 고속 디지털 코어에 적용한 결과 기존 PGC 배치 기법 대비 PGC 면적은 12.59~16.16%, 최대 IR drop은 8.49% 감소함을 확인하였다.

• 동력기계공학회지
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• 제17권5호
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• pp.52-57
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• 2013

In this paper, an analysis on exergy efficiency of high-efficiency R717 OTEC power system for the efficiency and pressure drop in main components were investigated theoretically in order to optimize the design for the operating parameters of this system. The operating parameters considered in this study include turbine and pump efficiency, and pressure drop in a condenser and evaporator, respectively. As the turbine efficiency of R717 OTEC power system increases, the exergy efficiency of this system increases. But pressure drop in the evaporator of R717 OTEC power system increases, the exergy efficiency of this system decreases, respectively. And, in case of exergy efficiency of this OTEC system, the turbine efficiency and pressure drop in a condenser on R717 OTEC power system is the largest and the lowest among operation parameters, respectively.

• 전기학회논문지P
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• 제67권3호
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• pp.155-159
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• 2018

Recently, the expansion or establishment of facilities for the logistics system is increasing. Conveyor facilities play a major role in sorting and transporting logistics. Induction motors are widely used for the operation of these conveyor systems. In the logistics system, a large number of induction motors are used. These motors have a considerable distance from the power source side and have a low power factor. The installation position for the power factor compensation of the induction motor is very important. Since the voltage drop depends on the length of the line, it is an important parameter in capacitor capacity determination for power factor compensation. The capacity of the capacitors installed to compensate the power factor of the inductive load should be designed to the extent that self-excitation does not occur. In this study, we analyze the method of compensating the proper power factor considering the voltage drop and the installation position of the induction motor in the logistics system.

• 전력전자학회논문지
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• 제15권5호
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• pp.411-416
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• 2010

본 논문에서는 변압기 기반 전압변동 발생기의 직렬변압기에 의한 전압강하 특성을 분석하였다. 전압변동 발생기의 회로구성 방식에는 여러 가지가 있으나 본 논문에서는 비교적 비용이 저렴하고 신뢰도가 높은 직렬변압기를 사용한 방식에 대해 다루고자 한다. 직렬변압기에 의한 전압강하는 변압기의 %Z와 부하용량 및 부하역률에 의해 결정된다. 직렬변압기의 설계가 잘못되면 전압강하가 심각하게 발생하여 제대로 된 성능을 확보할 수 없다. 본 논문에서는 10kVA급 전압변동 발생기에 대해 %Z가 4%인 직렬변압기를 사용한 경우 부하역률에 따른 전압강하를 분석하였으며 지상 부하일수록 전압강하가 증가하고 역률이 0.85 지상인 경우 전압강하가 4% 발생함을 시뮬레이션 및 실험을 통하여 확인하였다.

• Nuclear Engineering and Technology
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• 제27권1호
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• pp.96-104
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• 1995

EPRI URD requires that the reactor be capable of accommodating an unintended CEA drop without initiating a trip and operating at a reduced power with ay single CEA fully inserted. YGN 3 and 4 reactors have 12-finger CEAs, and the CPCS will trip the reactor due to their large reactivities when one of them is dropped at a high power. The ABB-CE reactor power cutback system has been proposed to be used against the 12-Finger CEA drop to avoid the reactor trips. The results of study show that the reactor power cutback can prevent the reactor trips of the 12-Finger CEA drop when the CPCS has enough operating thermal margin (more than 9％ for YGN 3&4 Cycle 1). It is noted, however, that the probability of a 12-Finger CEA drop is very low, less than one per 100 reactor years for YGN 3& and System 80$^{+}$ plants.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2491-2498
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• 2020

The paper concentrates on an experimental study of the pressure drop in double-layered packed beds formed by glass spheres, having the configuration of horizontal and vertical stratification. Both single-phase and two-phase flow tests are performed. The pressure drop during the test is recorded and the measured data are compared with those of homogeneous beds consisting of mono-size particles. The results show that for the horizontally stratified bed with fine particles atop coarse particles, the pressure drop in top layer is found higher than those of homogenous bed consisting of the same smaller size particles, while the measured pressure drop of bottom part is similar with those of similar homogenous bed. But for the homologous bed with upside-down structure, the stratification has little or no effect on the pressure drop of the horizontally stratified bed, and the pressure drop of each layer is almost same as that of homogeneous bed packed with corresponding spheres. Additionally, in vertically stratified bed, the pressure drops on the left and right side is almost equal and between those in homogeneous beds. It is speculated that vertically stratified structure may lead to lateral flow which redistributes the flow rate in different parts of packed bed.

• 전기학회논문지
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• 제65권11호
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• pp.1919-1924
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• 2016

In general, Diode rectifier has been applied to DC traction power supply system. Diode has some characteristics which is voltage drop in inverse proportion of load because of non-controlled switch, and cannot flow a current in reverse bias. So, voltage drop occurs frequently, and regenerated power cannot use in substation. The PWM rectifier is able to control output voltage constantly to reduce voltage drop and to use regeneration power without additional inverter. This paper proposes analysis algorithm for DC traction power supply system with PWM rectifier.

• 한국정보통신학회논문지
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• 제12권10호
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• pp.1835-1839
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• 2008

파워 매니지먼트는 휴대용 전자 기기에서 매우 중요한 역할을 한다. 휴대용 전자 기기는 배터리의 수명을 증가시키기 위해 LDO와 같은 파워 효율적인 파워 매니지먼트를 요구한다. 그래서 배터리 전원을 사용하는 휴대폰, 카메라 레코더, laptop, 자동차 전장용, 산업용 기기 등의 응용에서는 배터리의 전압변동이 크기 때문에, 배터리 전원을 그대로 사용하지 않고 내부회로의 전원을 제공해 주는 LDO를 이용한다. 레귤레이터는 배터리 전원전압 보다 낮은DC전압을 내부회로에 제공하며, 큰 변동을 보이는 배터리 전압에 관계없이 일정한 DC전압을 제공할 수 있다. 본 연구에서는 0.18um CMOS 공정기술로 제작된 온칩 LDO의 파워 세이브 모드 전류 특성과 IR-Drop 특성을 파악해 보았다.

• 한국초전도ㆍ저온공학회논문지
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• 제25권2호
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• pp.19-24
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• 2023

Recently, interest in renewable energy such as solar and wind power has increased as an alternative to fossil fuels. Renewable energy sources such as large wind farms require long-distance power transmission because they are located inland or offshore, far from the city where power is required. High-Temperature Superconducting (HTS) power cables have more than 5 times the transmission capacity and less than one-tenth the transmission loss compared to the existing cables of the same size, enabling large-capacity transmission at low voltage. For commercialization of HTS power cables, unmanned operation and long-distance cooling technology of several kilometers is essential, and pressure drop characteristic is important. The cryostat's spiral corrugation tube is easier to bend, but unlike the round tube, the pressure drop cannot be calculated using the Moody chart. In addition, it is more difficult to predict the pressure drop characteristics due to the irregular surface roughness of the binder wound around the cable core. In this paper, a CFD model of a spiral corrugation tube with a core was designed by referring to the water experiments from previous studies. In the four cases geometry, when the surface roughness of the core was 10mm, most errors were 15% and the maximum errors were 23%. These results will be used as a reference for the design of long-distance HTS power cables.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.940-947
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• 2011

Load capacity varies according to a day of the week in traction power supply system, because time schedule in railway is changed as demand for passengers and freights. Therefore, Voltage drop also varies as load capacity. In Korea railway, Voltage collected from catenary in train is decreased, as load supplied traction power supply system is increased. Therefore, investigation about voltage drop should be performed, before development of countermeasure against voltage drop. The investigation can be performed by simulation or field test. Naturally, field test is more precise than simulation. In addition, field test should be carried out at peak load. This paper presents test and analysis about voltage drop in railway. The test is performed in both a day of the week and weekend. The analysis is figured out comparison load capacity between two days and voltage drop across terminal.