• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.100.1-100.1
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• 2011

Electrochemical impedance spectroscopy(EIS) are using widely as a useful technique mainly in the field of electrochemical for the analysis of electrode reactions or characteristics of the composites. The response analysis of the systems technique provides comprehensive informations about the characteristic and structure of complex and internal reaction. The EIS is the method to measure impedance of the measurement target classified by the frequency, it select the equivalent impedance model to give same response from the result and it calculate the parameter. Therefore, the chemical reaction inside the fuel cell is to modeling to electrical impedance. And as repeating the same experiment in each of the operating point, we can get each different parameter. As a result, we can establish the equivalent impedance model in each operating point. Therefore, if we use these models, we can evaluate the fuel cell without the internal design parameter of the fuel cell as required in existing modeling. The EIS is used typically technique for distinguish status of fuel cell called SOH(State Of Health). When the fuel cell is degradation, Efficiency and health of the fuel cell is reduced because internal impedance is increase. As usage of these principles, we can evaluate state of fuel cell through the impedance analysis of fuel cells. In this study, we are presents EIS distinction system and algorithm for residential fuel cell systems. At the time of the fuel cell installation in the fields, the EIS system and proposed algorithm will be able to apply as technique for efficiency and performance evaluation about fuel cell system.

• 한국항행학회논문지
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• 제20권1호
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• pp.86-92
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• 2016

최근 사람이 다수 붐비는 지역에 스마트 폰이나, 태블릿 등을 바로 충전할 수 있는 태양광 모듈이 설치되어 서비스를 제공하고 있다. 하지만 설치비용이 높아 이용인원이 적은 지역에 설치 할 경우 비용측면에서 부담이 되며, 협소한 지역에는 설치가 어려운 문제점이 존재한다. 본 논문에서는 이와 같은 문제를 해결하기 위해 국가에서 제공하는 데이터와, 실제 환경에서 수집한 데이터를 이용하여 각 지역에 해당 서비스를 제공받는 사람에 대한 정보를 분석 한 후 대기시간 및 태양광 충전시간을 고려하여 환경에 맞는 최적의 전력을 수집 및 제공하는 시스템을 제안하였다. 실험결과 수집전력이 충전전력량보다 상회하여 충전이 지연되지 않았으며, 약 95분경에 스마트 폰의 전력을 모두 충전할 수 있음을 확인하였으며, 버스 대기시간인 10분에서 20분 사이에 스마트 폰이 한 대일 경우 약 50%가량을 충전할 수 있으며, 여러 대일 경우 약 20%가량을 충전할 수 있음을 확인하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권11호
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• pp.532-537
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• 2006

Lightning induced faults accounts for more than 66% at the transmission lines of KEPCO. The lightning causes damages to power system equipments including transmission line, the blackout of electricity and the electro-magnetic interference. Because of this reason, we need the real time lightning information for the optimal operation of power system. And, it is required to obtain and accumulate the lightning current parameters for the insulation design. In 2005, KEPRI constructed a lightning detection network, the KLDNet (i.e. Kepco Lightning Detection & Information System) and launched a lightning information service for KEPCO customers. It is intended to provide data service on the operation of transmission lines and collect lightning-related data, which is the most important factor regulating power system design and operation. The new system will replace LPATS, the old detection system, which has been operating since 1995 and is rapidly failing in terms of both detection performance and location accuracy. The purpose of this paper is to explain the work performed and the results of that work in performing a site survey of several locations. The purpose of the site survey is to find locations acceptable for the installation of a lightning location receiver in support of a Lightning detection system(LDS). A restriction was placed on the surveyed locations, as they must belong to the Korea Electric Power Company. This requirement was made to facilitate the communication needs of the LDS network. Total of 15 sites were evaluated as possible LDS sensor sites. Some of the sites were rejected for physical reasons and therefore no electrical testing was performed. Of the 15 sites, total of 10 sites were considered acceptable and 5 sites were rejected for various reason. In this paper, we would like to explain the site survey and detection efficiency for LDS.

• 한국전기전자재료학회논문지
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• 제26권9호
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• pp.669-676
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• 2013

In this study, we introduce a polymer(polyimide) based pressure sensor to measure real-time heart beat and blood pressure. The sensor have been designed with consideration of skin compatibility of material, cost effectiveness, manufacturability and wireless detection. The designed sensor was composed of inductor coils and an air-gap capacitor which generate self-resonant frequency when electrical source is applied on the system. The sensor was obtained with metalization, etching, photolithography, polymer adhesive bonding and laser cutting. The fabricated sensor was shaped in circular type with 10mm diameter and 0.45 mm thickness to fit radial artery. Resonant frequencies of the fabricated sensors were in the range of 91~96 MHz on 760 mmHg pressurized environment. Also the sensor has good linearity without any pressure-frequency hysteresis. Sensitivity of the sensor was 145.5 kHz/mmHg and accuracy was less than 2 mmHg. Real-time heart beat measurement was executed with a developed hand-held measurement system. Possibility of real-time blood pressure measurement was showed with simulated artery system. After installation of the sensor on skin above radial artery, simple real blood pressure measurement was performed with 64 mmHg blood pressure variation.

• 지구물리와물리탐사
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• 제19권1호
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• pp.45-50
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• 2016

일반적으로 전기비저항 탐사에서는 편의상 점 전원을 사용한다. 만약 철제 케이싱과 같이 긴 전극을 사용한다면 전기비저항 탐사의 탐사 깊이가 증가할 것으로 기대된다. 그러나 긴 전극을 사용하여 회득된 전기비저항 탐사 자료는 통상적인 자료 해석 프로그램으로 처리할 수 없다. 이는 긴 전극에 의해 생성된 1차 전위가 점 전원에 의한 1차 전위와는 서로 다르기 때문이다. 이 연구에서는 긴 전극을 여러 개의 연속된 점 전원으로 대치하는 새로운 전기비저항 탐사 자료 처리 방법을 제안하였다. 이 방법에 의한 전위 분포를 해석적/수치적 해와 비교한 결과, 유한 차분법이나 유한 요소법에 의한 긴 전극을 사용하는 전기비저항 탐사 모델링이 가능함을 확인하였다.

• 한국도로학회논문집
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• 제16권6호
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• pp.51-57
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• 2014

PURPOSES : An conventional method for electric power generation is converting thermal energy into mechanical energy then to electrical energy. Due to environmental issues such as global warming related with $CO_2$ emission etc., were the limiting factor for the energy resources which resulting in extensive research and novel technologies are required to generate electric power. Thermal energy harvesting using thermoelectric generator is one of energy harvesting technologies due to diverse advantages for new green technology. This paper presents a possibility of application of the thermoelectric generator's application in the direct exchange of waste solar energy into electrical power in road space. METHODS : To measure generated electric power of the thermoelectric generator, data logger was adopted as function of experimental factors such as using cooling sink, connection methods etc. Also, the thermoelectric generator、s behavior at low ambient temperature was investigated as measurement of output voltage vs. elapsed times. RESULTS : A few temperature difference between top an bottom of the thermoelectric generator is generated electric voltage. Components of an electrical circuit can be connected in various ways. The two simplest of these are called series and parallel and occur so open. Series shows slightly better performance in this study. An installation of cooling sink in the thermoelectric generator system was enhanced the output of power voltage. CONCLUSIONS : In this paper, a basic concepts of thermoelectric power generation is presented and applications of the thermoelectric generator to waste solar energy in road is estimated for green energy harvesting technology. The possibility of usage of thermoelectric technology for road facilities was found under the ambient thermal gradient between two surfaces of the thermoelectric module. An experiment results provide a testimony of the feasibility of the proposed environmental energy harvesting technology on the road facilities.

• 한국전기전자재료학회논문지
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• 제29권5호
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• pp.274-278
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• 2016

A road energy harvester was designed and fabricated to convert mechanical energy from the vehicle load to electrical energy. The road energy harvester is composed of 20 piezoelectric materials. This study attempted to evaluate output depending on pavement materials when paving road piezoelectric energy harvester in the road. Harvester is the bender type and is the method of supporting the both ends of piezoelectric material and applying the load in the middle part. Harvester was paved in the type paved with asphalt, type paved with cement and in the exposed type not covering the top of harvester. The output characteristics were compared and evaluated depending on changes in vehicle load and vehicle speed changes. As vehicles, truck (11.9 ton), SUV(1.6 ton) and sedan (1.5 ton) were used and the output characteristics when driving at the interval of 10 km/h from 10 km/h to 100 km/h were evaluated.

• 전기전자학회논문지
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• 제24권3호
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• pp.691-698
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• 2020

해상풍력 발전단지의 전력망 연계방식에 따라 설치비용이나 고장전류의 크기가 달라진다. 그렇기 때문에 단지의 용량과 위치 등을 고려한 효율적인 전력망 연계 방법이 필요하다. 특히 해상풍력 발전단지의 전력케이블은 대부분 비용 및 효율적인 부분을 고려하여 3-core를 사용한다. 케이블 단락 같은 고장이 발생하면 케이블 전체를 교체해야 하므로 수리비용 및 터빈 정지 기간을 고려하였을 때 비용적인 측면에서 상당한 손실이 발생할 수 있다. 따라서 본 논문에서는 제주해상에 설치될 100 MW 풍력단지에 방사형, 링형, 성형 방식을 도입하여 이에 따른 3상 단락고장을 PSCAD/EMTDC 프로그램을 활용하여 컴퓨터 해석을 수행하고, 그 결과를 분석하여 모델 단지에 알맞은 전력망 연계방식을 제안하고자 한다.

• Smart Structures and Systems
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• 제15권1호
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• pp.135-150
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• 2015

Large concrete structures are prone to cracks and damages over time from human usage, weathers, and other environmental attacks such as flood, earthquakes, and hurricanes. The health of the concrete structures should be monitored regularly to ensure safety. A reliable method of real time communications can facilitate more frequent structural health monitoring (SHM) updates from hard to reach positions, enabling crack detections of embedded concrete structures as they occur to avoid catastrophic failures. By implementing an unconventional mode of communication that utilizes guided stress waves traveling along the concrete structure itself, we may be able to free structural health monitoring from costly (re-)installation of communication wires. In stress-wave communications, piezoelectric transducers can act as actuators and sensors to send and receive modulated signals carrying concrete status information. The new generation of lead zirconate titanate (PZT) based smart aggregates cause multipath propagation in the homogeneous concrete channel, which presents both an opportunity and a challenge for multiple sensors communication. We propose a time reversal based pulse position modulation (TR-PPM) communication for stress wave communication within the concrete structure to combat multipath channel dispersion. Experimental results demonstrate successful transmission and recovery of TR-PPM using stress waves. Compared with PPM, we can achieve higher data rate and longer link distance via TR-PPM. Furthermore, TR-PPM remains effective under low signal-to-noise (SNR) ratio. This work also lays the foundation for implementing multiple-input multiple-output (MIMO) stress wave communication networks in concrete channels.

• 조명전기설비학회논문지
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• 제20권4호
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• pp.21-28
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• 2006

본 논문에서는 Ballard사의 1.2[kW]급 연료전지와 연료전지의 저전압($28{\sim}43[VDC]$)을 승압(380([VDC])시키기 위한 풀-브리지 직류-직류 컨버터, 그리고 승압된 직류 링크전압을 교류 전압(220[VAC]), 60[Hz]으로 변환하기 위한 단상 풀-브리지 인버터로 구성된 연료전지 발전용 전력변환시스템 중 풀-브리지 고주파 절연형 영전압 영전류 스위칭 위상 천이 펄스폭 변조 직류-직류 컨버터를 제안하였다. 제안한 풀-브리지 고주파 절연형 영전압 영전류 스위칭 위상 천이 펄스폭 변조 직류-직류는 프리휠링 다이오드를 포함한 탭부 인덕터 필터를 이용하여 순환 전류를 저감시켰으며, 스위치 및 변압기의 턴-온, 턴-오프시에 오버슈트 전압이나 과도현상이 발생하지 않는다. 그리고 넓은 출력 전압 조정에도 효율을 $93{\sim}97[%]$정도 얻을 수 있으며, 출력 부하전류의 변화에 대해 거의 일정한 출력 전압 특성을 가졌다.