• 전기학회논문지
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• 제65권4호
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• pp.539-546
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• 2016

With the growing interest of microgrid systems all over the world, many studies on microgrid operation are being carried out. The battery energy storage system(BESS) and the diesel generator are key equipments in the microgrid. In this paper, we analyze the characteristics of fuel consumption according to the power ratio of the diesel generator. Then, the formula to represent the unit cost of generation according to the power ratio of the diesel generator is derived. A new modeling of battery operation is presented considering the lifetime reduction according to increasing the cycles of charge/discharge operation of the battery. The methodology of determining the optimal operation of the battery and the diesel generator is presented by the use of the formula of fuel consumption of the diesel generator and the new modeling of battery operation. It is shown that this optimization methodology can be applied effectively for economical operation of the BESS and the diesel generator of a microgrid by case studies.

• 한국환경과학회지
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• 제21권9호
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• pp.1069-1078
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• 2012

This study was performed to evaluate the asbestos exposure levels and to calculate excess lifetime cacer risks(ELCRs) in asbestos-containing buildings for maintenance and management. The range of airborne asbestos concentration of 33 buildings was 0.0018 ~ 0.0126 f/cc and one site exceeded indoor air-quality recommended limit 0.01 f/cc. And ELCRs based on US EPA IRIS(Integrated risk information system) model are 1.5E-06 ~ 3.9E-05 levels, and there was no site showed 1.0E-04 (one person per million) level or more, and 11 sites showed 1.0E-05 (one person per 100,000 people) level or more. To prevent the release of asbestos fibers, it needs operation and maintenance of asbestos-containing building materials, and there are some methods such as removal, repairment, enclosure and encapsulation. In conclusion, a risk-based air action level for asbestos in air is an appropriate metric for asbestos-containing building management.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.204-207
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• 2005

A reliable and practical finite element modeling technique to predict the lifetime of automotive electronics is important for engineers in reliability. In reliability evaluation on the automotive electronics, most studies rarely used FE model verification process. The material properties and boundary conditions are very important factors in this process to assure the reliability of the automotive electronics. This study aims to develop a better and more accurate FE model in order to predict fatigue life of the automotive electronics using Virtual Qualification lifetime assessment techniques. After conducting the modal analysis by the experiments to grasp a system characteristic, this paper presents material properties and boundary conditions that is obtained by the comparisons of FEA simulation results using DOE technique and the experiment results.

• 전자공학회논문지
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• 제53권4호
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• pp.87-93
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• 2016

본 논문에서는 모바일 애드혹 무선 센서 네트워크에서 RF 에너지 하베스팅 기반 라우팅 프로토콜을 제안한다. 제안된 라우팅 프로토콜의 주요한 특징 및 기여도는 다음과 같다. 첫째, 모바일 센서 노드의 잔여에너지와 RF 에너지 하베스팅을 기반으로 한 라우팅 경로 설정. 둘째, 네트워크 및 경로의 생존시간을 증가시키기 위해서 모바일 센서 노드들의 에너지를 기반으로 한 경로의 평균 가용성과 안정성을 고려하여 경로를 설정한다. OPNET을 사용한 제안된 라우팅 프로토콜의 성능평가 결과는 RF 에너지 하베스팅을 기반으로 하여 경로의 가용성과 안정성을 고려한 라우팅 방법이 경로의 라이프타임을 효과적으로 향상 시키는 것을 확인 할 수 있음을 보여준다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.67-70
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• 2006

This paper deals with a single crystalline silicon (SCS) RF MEMS switch for telecommunication system applications. The proposed SCS switch was fabricated using a silicon-on-glass (SiOG) process and its performances in terms of RF responses, switching time, lifetime were characterized. The proposed SCS switch consists of movable plates, mechanical spring structures, which are composed of robust SCS, resulting in mechanically good stability, The measured actuation voltage was 30 V, and with this applied voltage, the insertion loss and isolation characteristics were measured to be 0.05 and 44.6 dB at 2 GHz respectively. The measured switch ON and OFF time were 13 and $9{\mu}s$, respectively. The lifetime of the fabricated switch was tested. Even after over 1 billion cycles repeated ON/OFF actuations, the switch maintained its own characteristics.

• 전력전자학회논문지
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• 제9권2호
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• pp.187-193
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• 2004

PDA, 스마트폰, USP 및 전기자동차와 같은 전기적 장치의 전력공급을 위하여 배터리가 직렬로 연결된 다중 셀을 만들어 일반적으로 사용한다. 이 경우 개별 셀 전압의 편차가 발생되면 배터리의 수명과 용량은 낮아지게 된다. 셀에서 전압의 안정화상태를 유지하기 위한 셀 전압을 안정화시키는 효율적인 방범은 없어서는 안 될 중요한 사항이다. 본 논문에서는 휴대형 가전기기에 적용하기 위해 마이크로컨트롤러를 사용한 다중 셀용 밸런싱 회로의 설계에 대하여 제안한다. 밸런싱 시스템은 충전되는 주기 동안 밸런싱 동작을 이행하며 마이크로컨트롤러로서 제어된다. 제안된 방법은 충전기와 레코드를 사용하여 실험을 통해 증명하였다. 실험결과에서 개별 배터리의 용량, 수령, 성능이 향상됨을 보여준다.

• 한국항공우주학회지
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• 제43권1호
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• pp.62-71
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• 2015

정지궤도위성은 궤도상에서 위치변화를 제어하기 위해 추력기를 사용하고 운용수명에 맞추어 적정한 양의 액체추진제를 탑재한다. 그러므로 정지궤도위성의 수명은 추진제 잔여량에 좌우되고 정확한 잔여추진제량 측정은 조기 수명종료로 야기되는 경제적 손실을 완화시킬 뿐만 아니라 후속위성의 대체나 위성망 운용계획 등에 매우 중요하다. 잔여추진제량을 측정하는 방법은 주로 PVT 방법, 열질량법, 회계식 방법이 사용된다. 본 논문에서는 회계식방법을 사용하기 위한 천리안위성 이원추진시스템의 모델링과 몬테카를로 방법을 이용하여 천리안위성의 궤도전이 소요 추진제량을 분석하였다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제15권3호
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• pp.154-162
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• 2015

We have performed accelerated photo-degradation test using a 10-Sun level high irradiance $Weather-Ometer^{(R)}$ (10-Sun Ci5000) in an attempt to study acceleration and correlation between accelerated and service conditions for ink-jet ink. The accelerated test was used to predict lifetimes of ink-jet ink through the calculation of scaling factor for intensity of irradiance and duration of usage combined with estimation of lifetime distribution and inverse power model as a life-stress model. The lifetimes and acceleration factors for foreign and domestic inks were compared with each other. The results showed that the failure mechanisms and life-stress models for ink-jet ink were different among the color of ink which means that we might be in need of further study by color of inks.

• 전기학회논문지
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• 제65권12호
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• pp.2225-2231
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• 2016

In order to overcome the problem of fossil fuel energy, electric vehicle (EV) has been used in recent years. The important issues of EV are driving distance and lifetime related to EV efficiency. A voltage source converter is one of the main components of EV which can be operated with various pulse width modulation (PWM) schemes such as continuous PWM schemes and discontinuous PWM schemes. These PWM schemes will cause the effects on the efficiency of converter system and the lifetime of EV. Therefore, this paper proposes an analysis of the PWM schemes for the power converter on the EV. The objective is to find out a best solution for the EV by comparing the total harmonic distortion (THD) and transient response between the various PWM schemes. The operation of traction motor on the EV with the PWM schemes will be verified by using Psim simulation program.

• KIEAE Journal
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• 제12권6호
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• pp.29-38
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• 2012

The current building energy efficiency rating certification regulation on apartment houses evaluates only the saving rate of energy consumed during operation, i.e. use, of a building, but doesn't consider the energy consumptions and environmental load($CO_2$) emissions occurring during the whole lifetime of a building. So this study calculated the energy consumptions and environmental load emissions occurring during the whole lifetime of a building, selected reference schemes and alternative items by design variables to present a design draft considering energy efficiency and environmental performance, and evaluated the total cost by combining and calculating its direct cost(material and heating cost) and indirect cost(environmental cost), for an existing apartment house as an evaluation object. As a result of analysis, the change of heating cost by alternative items of design variables showed a 4~8% change rate compared to the reference scheme, and the material cost of design variable 7 showed a maximum 4.4 times change rate in the alternative plan 6 compared to the reference scheme. The environmental cost showed a similar change rate to the material cost change rate in general, but showed a similar environmental cost change rate to the heating cost change rate in case of design variables 4-1, 4-2, 7.