• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 B
• /
• pp.656-659
• /
• 2000

Recently, the skeleton type 2-phase brushless DC motor has been used in electric home appliance for low price and low energy consumption. In this paper, we analyzed a skeleton type 2-phase BLDC motor using time-step finite element method. And the validity of analysis is confirmed by measuring the flux distribution on the surface of permanent magnet and back-EMF. As well, we have calculated the dynamic characteristics of target motor considering the Hall sensor position. So, we have found the optimum switching position, and improved efficiency of 2-phase BLDC motor.

• 지구물리
• /
• 제6권2호
• /
• pp.89-97
• /
• 2003

For safety evaluation of a rockfill dam, it is often necessary to investigate spatial distribution and dynamic characterization of weak zones such as fractures. For this purpose, both seismic and electric methods are adopted together in this research. The former employs the multichannel analysis of surface waves (MASW) method, and aims at the mapping of 2-D shear-wave velocity (Vs) profile along the dam axis that can be associated with dynamic properties of filled materials. The latter is carried out by DC- resistivity survey with a main purpose of mapping of spatial variations of physical properties of dam materials. Results from both methods are compared in their signature of anomalous zones. In addition, downhole seismic survey was carried out at three points within the seismic survey lines and results by downhole seismic survey are compared with the MASW results. We conclude that the MASW is an efficient method for dynamic characterization of dam-filling materials, and also that joint analyses of these two seemingly unrelated methods can lead to an effective safety evaluation of rock-fill dam.

• 산업경영시스템학회지
• /
• 제30권4호
• /
• pp.111-117
• /
• 2007

Comparing with bar-code systems, RFID systems can supply more efficient work. Using RFID systems, logistic management systems could be helped effectively to gather real-time information. It's available to reduce the working time and object's delay time, and to deal with real-time information by using RFID system. Until now, based on how many pallets used, there is few study about best workload of RFID system. Therefore, in this study, both bar-code and RFID system simulations were executed for inspection process in distribution center. As a result, following the ware pallet quantity, the total cost of both working time and other delay times were calculated and the sensitivity analysis of total cost trend was executed.

• Applied Science and Convergence Technology
• /
• 제23권3호
• /
• pp.145-150
• /
• 2014

MgO thin films were deposited by internal ICP-assisted reactive-magnetron sputtering with bipolar pulse bias on a substrate to suppress random arcs. Mg is reactively sputtered by a bipolar pulsed DC power of 100 kHz into ICP generated by a dielectrically shielded internal antenna. At a mass flow ratio of $Ar/O_2$ = 10 : 2 and an ICP/sputter power ratio of 1 : 1, optimal film properties were obtained (a powder-like crystal orientation distribution and a RMS surface roughness of approximately 0.42 nm). A bipolar pulse substrate bias at a proper frequency (~a few kHz) prevented random arc events. The crystalline preferred orientations varied between the (111), (200) and (220) orientations. By optimizing the plasma conditions, films having similar bulk crystallinity characteristics (JCPDS data) were successfully obtained.

• 한국표면공학회지
• /
• 제29권5호
• /
• pp.338-344
• /
• 1996

This study was an investigation of plasma-induced damages on silicon substrate in the semiconductor manufacturing technology. The plasma-induced damage level on silicon substrate was analyzed and compared in various plasma etching systems. The analysis methods were therma wave, life-time recovery, SCA (Surface Charge Analyzer) and TRXF (Total Reflection X-ray Fluorescence) measurements, and the measured values were compared for each systems. In the comparison of the values which were obtained by a system that had low life-time recovery, there was not any differences in DC parameters. However, the reflesh time distribution of device of that system had decreased about 10 to 20m sec compared to a system which had high life-time recovery.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 C
• /
• pp.1559-1561
• /
• 2003

In northeast Asia, there will be several important HVDC transmission lines to be established in Korea and China for perspective electric network market. 5500V 4-inches High voltage thyristor can be used in the DC transmission and distribution of electric power system. In this application, many thyristors are connected in series for each thyristor valves. Therefore, the required low reverse-recovery charge QRR and low on-state voltage drop $V_{TM}$ for such thyristor is necessary to this application. In our work, the on-state and off-state voltage performance was simulated by commercial simulation software.

• Journal of Power Electronics
• /
• 제8권2호
• /
• pp.131-140
• /
• 2008

This paper presents a new control approach of DSTATCOM (distribution static compensator) for compensation of reactive power, unbalanced loading and harmonic currents under unbalanced non-sinusoidal ac mains. The control of DSTATCOM is achieved using Adaline based current estimator based on LMS algorithm to maintain source currents real and undistorted. The dc bus voltage of voltage source converter (VSC) working as DSTATCOM is maintained at constant voltage using a proportional-integral (PI) controller. The DSTATCOM system alongwith proposed control scheme is modeled in MATLAB to simulate the behavior of the system. The practical implementation of the DSTATCOM is carried out using dSPACE DS1104 R&D controller having TMS320F240 as a slave DSP. Simulated and implementation results are presented to demonstrate the effectiveness of the DSTATCOM with Adaline based control to meet the severe load perturbations with different types of loads (linear and non-linear) under distorted and unbalanced AC mains.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2014년도 전력전자학술대회 논문집
• /
• pp.102-103
• /
• 2014

본 논문에서는 ${\pm}750V$ LVDC 배전용 전원장치에 적합한 3레밸 NPC 정류기 시스템을 제안한다. 제안하는 정류기 시스템은 배선선로의 부하 불평형에 따른 NPC 정류기의 출력 전압 불평형 현상을 해결하기 위해서 출력전압 밸런스 알고리즘을 적용하였다. 제안하는 정류기 시스템은 50kVA 용량의 시제품의 실험을 통해서 성능을 검증하였다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2014년도 전력전자학술대회 논문집
• /
• pp.257-258
• /
• 2014

본 논문에서는 직류 마이크로그리드 시스템에서의 분산 에너지 저장장치 시스템을 위한 제어 알고리즘을 제안한다. 각 에너지 저장장치의 전력 분배를 위해 state of charge (SOC)와 배터리 노화에 따른 용량 변화를 고려한 적응 드룹 제어 방식을 제안한다. 각 에너지 저장장치의 SOC에 따라 오프셋 전압을 변화시킴으로써 각 에너지 저장장치 간의 SOC 밸런싱을 유지한다. 또한, 에너지 저장장치의 용량 변화에 따라 드룹 기울기 변수를 변화시켜, 노화에 따른 전력 분배를 유지하도록 한다. 48V 직류배전 시스템의 시뮬레이션을 통해 제안된 제어방법을 검증한다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2012년도 전력전자학술대회 논문집
• /
• pp.375-376
• /
• 2012

본 논문에서는 소규모 수용가의 직류 배전 시스템의 타당성을 검증하기 위하여, 가정 및 빌딩용 직류 배전 시스템을 구축하여, 교류 및 직류 전원 공급에 따른 효용성을 비교/검증하였다. 직류 전원을 인가하기 위하여 5대 가전기기(냉장고, TV, 세탁기, 에어컨, 노트북, 컴퓨터)를 직류 전원 인가가 가능하도록 전원 시스템을 변경하였으며, 직류 전원 공급을 위한 양방향 교류/직류 컨버터를 제작하였으며, 직류 전원 인가에 따른 아크 발생을 저감하기 위한 직류 콘센트를 설계/제작하여 직류 배전 시스템을 구축하였다. 또한 LED, 데이터 센터 등 직류 전원이 요구되어지는 분야에 적용하기 위한 고효율 직류-직류 컨버터를 개발하여 적용하고자 하였으며, 에너지 저장장치, 신재생 에너지원과 결합된 직류 배전 시스템을 구성하고자 한다.