• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.11
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• pp.2015-2021
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• 2008

Recently, with the growth of photovoltaic system, many researchers and companies have concerned about the multi-level inverter which has an efficiency of boosting voltage. In this paper a novel structure of multi-level converter for reducing ripple of output voltage is proposed. In the proposed converter Buck converters are connected in series to generate the output voltage and the ripple of output voltage can be reduced compared with the exiting Buck converter. Especially when outputting lower output voltage the number of acting switching elements is less and the result of ripple reducing is more obvious. This paper implements a multi-level switching function based on the FPGA.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.1
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• pp.6-12
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• 2010

Fiber optic sensor using fiber Bragg grating(FBG) probes is used for monitoring strain and temperature distributed on the wide surfaces of large structures. In this paper, in order to use many FBG probes in one optical fiber line, we propose a complex multiplexing technology which is composed of two techniques, one is time division multiplexing and another is wavelength division multiplexing. However, we only investigate the characteristics of time division multiplexing because FBG sensors basically can be operated by wavelength division multiplexing. We calculate the optimal reflectivities and the lengthwise location of five FBG probes in serial connection in order to obtain the unique reflected intensities from the FBG probes. We fabricate five FBG probes with the reflectivities of 13%, 16%, 25%, 40% and 80%, which are determined by the theoretical calculation, and observe the signal reflected from each FBG in the time domain from the experiment. There are differences between experimental and theoretical results caused by the signal noise and the differences of reflectivities of FBG probes. But the experimental results shows the reflected signals of five FBG probes which prove the availability of complex multiplexing.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.411-412
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• 2016

최근 퍼스널 모빌리티에 대한 관심과 수요가 증대됨에 따라 전기에너지를 구동원으로 하는 소형 이동형 제품을 생활속에서 쉽게 접할 수 있게 되었다. 이러한 퍼스널 모빌리티 제품은 자이로센서 기술이 접복된 바퀴가 하나인 외발 전동휠과 세그웨이류의 제품, 전동퀵보드, 전동스쿠터 등 다양한 제품이 출시되고 있다. 또한 이들 제품의 구동전원은 대부분 리튬이차전지가 사용되고 있다. 본 논문에서는 충전과 방전을 반복하는 다셀이 직렬로 구성된 리튬 이차전지 배터리팩에서 발생되는 셀간 편차와 이로 인해 배터리팩의 전체적인 효율성이 저하되는 것을 방지하는 셀 밸런싱에 관한 기술로 과거 완속형의 표준충전에 적합한 1단 밸런싱의 문제점을 보완하기 위해 표준충전과 급속충전을 임의로 선택하여 사용하는 경우에도 정상적인 셀 밸런싱 수행은 물론 빠른 셀 밸런싱을 수행하기 위한 기법에 대해 살펴보았다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1149-1150
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• 2011

일반적으로 BTB STATCOM은 계통 분리 운전이나 이종계통의 연계 등의 목적으로 이용한다. 기본 구성으로는 두 대의 STATCOM을 직렬로 연결하여 계통에 삽입되며, 구조 및 개념상 HVDC와 유사한 특징을 갖고 있다. 본 논문에서는 국내에서는 처음으로 독자 개발에 성공한 STATCOM의 기술을 바탕으로 BTB STATCOM의 제어 알고리즘을 설계하고, PSCAD/EMTDC를 이용하여 BTB STATCOM의 모델링 및 계통 연계 모의를 수행하였다. 모델링 및 모의를 통하여 설계 및 개발한 BTB STATCOM의 제어 알고리즘이 정상동작하며, 성공적으로 BTB STATCOM의 역할을 수행할 수 있음을 확인하였다.

• IE interfaces
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• v.17 no.spc
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• pp.69-78
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• 2004

This paper presents a simulated algorithm(SA) for the optimal reliability design problem of a series system with multiple component choices incorporated at each subsystem. The objective of the problem is to maximize the system reliability while satisfying some constraint on system budget. The problem is formulated as a nonlinear binary integer programming problem and characterized as an NP-hard problem. The SA algorithm is developed by introducing some solution-improvements methods. Numerical examples are tested and the results are compared. The results have demonstrated the efficiency and the effectiveness of the proposed SA algorithm.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.3
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• pp.389-396
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• 1986

A pulsed ultrasonic doppler flowmeter for mesurements of velocity profils in man is described. The device projects a beam of ultrasound in burst of 570 ns duration at 3.5 MHz. The back-scattered signals are processed to produce a signal oxrresponding to the mean velocity over a small region of the flowing stream. The observation range of 112mm is divided into 128 depth channels. The size of this sample volume determines the flowmeter sensitivity and accuracy. The device uses a quadrature detector to detect the direction of the moving target(hemoglobin). The main feature of the novel instrumnet is its simple hardware structure due to sequential signal processing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2359-2369
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• 2009

The study on the multi-level inverter has been increasingly progressing to reduce the switching loss and improve the THD of output current in photovoltaic inverter. Recently, the main topics of multi-level inverter are to reduce the number of devices maintaining the power quality. Therefore, the novel topology was proposed for these problem which is composed of the isolated H-bridge multi-level inverter using the three phase low frequency transformer. The proposed multi-level inverter may not be need for a independent DC power, diode and capacitor. Specially, It has a advantage in generating high voltage source. The proposed approach is verified through simulation and experiment.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.990-991
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• 2008

본 논문에서는 절연형 풀브릿지 컨버터의 고조파 변압기 2차측을 직렬로 연결하여 스위칭 주파수 증대효과가 있는 새로운 전력변환기를 제안하였다. 제안된 컨버터는 기존 방식에 비해 정류부와 필터부의 일원화가 가능한 구조로 수동소자의 수를 대폭 줄일 수 있다. 또한 제안된 전력변환기 구조에서 출력전압의 리플과 높은 승압비를 유지하기 위한 새로운 가변 위상 변위형 스위칭 방식을 제안하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.4
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• pp.326-333
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• 2004

This research proposes a high frequency resonant inverter for high power conversion apparatus, which is consist of two L-C linked full-bridge inverter using MOSFET in order to distribute voltage and current of the devices. As an output power control strategy, the time sharing control method is applied. From the computer simulation results, the inverters and devices can be shared properly voltage and current rating of the system. And also, theoretical characteristics of the proposed circuit are compared with experimental results.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.29-32
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• 2001

This paper describes a development of the integrated controller system for car electrical signal control with CAN communication protocol. The CAN protocol is a robust serial bus system for the control of distributed module in the multiplexed network. After a brief of the main features of the CAN will be addressed, this paper presents the result of the development of the integrated hardware system overall control program.