• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2176_2177
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• 2009

This paper describe the power quality measuring result of the inter-connected residental PV system. The power quality measuring for inter-connected residental PV system are important to verify their performance and effect of power distribution system with inter-connected residental PV system. Also, these power quality measuring and analysis are essential to improve electrical safety. In order to evaluate influence of power distribution system with inter-connected residental PV system, we measure and analyze power quality index such as power, voltage, current, harmonic, THD, flicker index, power factor and frequency using DEWE5000.

• 한국산학기술학회논문지
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• 제19권2호
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• pp.516-529
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• 2018

기업의 사회적 책임에 대한 인식과 요구가 증대되면서, 사회적 기여를 위한 기업의 활동이 다양해지고 있는 추세이다. 그럼에도 불구하고, 정기적으로 실시하는 관련 설문 조사에 따르면 기업의 사회 공헌활동에 대해 국민이 만족하지 못하는 것으로 나타났으며, 기업과 국민의 사회공헌활동에 대한 관점이 다른 것을 파악할 수 있었다. 이에 따라 다양한 사회공헌활동을 구체적으로 분류하여 사회에 미치는 영향을 파악하고자 한다. 본 연구에서는 기업 사회공헌활동과 성과에 대한 연관성을 파악하고자 사회공헌활동을 "사회문화적자원 활동", "사회간접적자원 활동" 및 "경제적자원 활동" 총 3가지 요인으로 분류하고, 요인별로 기업 간 연계활동과 지역발전성과에 미치는 영향을 파악하였다. 분석결과, 첫째, '사회문화적자원'과 '사회간접적자원' 활동은 지역 내 '기업 간 연계 활동'에 정(+)의 영향을 미치는 것으로 나타났다. 둘째, '지역 내 기업 간 연계' 활동이 활발할수록 '지역발전성과'에 정(+)의 영향을 미치는 것으로 나타났다. 셋째, '경제적자원' 활동은 '지역발전성과'에 정(+)의 영향을 미치는 것으로 나타났으며, 넷째, '사회문화적자원'과 '사회간접적자원' 활동은 지역 내 기업 간의 연계를 통해 '지역발전성과'에 간접적인 정(+)의 영향을 미치는 것으로 나타났다. 본 연구를 바탕으로 기업의 사회공헌활동과 성과에 대한 연관성을 정량적으로 파악하고 제시하였다.

• 한국세라믹학회지
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• 제41권1호
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• pp.19-23
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• 2004

The Hertzian indentation contact damage behavior of porous alumina with controlled pore shape was investigated by experiments. Porous alumina ceramics containing well-defined pore shape, size and distribution were prepared by incorporation of fugitive spherical starch. Porous alumina with isolated pore structure was prepared with porosity range up to 30%. The indentation stress-strain curves of porous alumina were constructed. Elastic modulus and yield stress can be obtained from the stress-strain relationship. Impulse excitation method for the measurement of elastic modulus was also conducted as well as Hertzian indentation and was confirmed as a useful tool to evaluate the elasticity of highly porous ceramics. Elastic modulus of the inter-connected pore structure is more sensitive to porosity than that of the isolated pore structure. When the specimen had isolated pore structure, higher yield point was obtained than it had inter-connected pore structure. This study proposed that the elastic modiulus of porous ceramics is strongly related to not only porosity, but also the structure of pore.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2000년도 추계 학술대회논문집
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• pp.1-8
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• 2000

In this work, Internet Supercomputing methodology is introduced and the concept is materialized for large-scale finite element analysis. The primary resources of Internet Supercomputing are numerous idling PCs connected by Internet with no regards to their locations. Therefore, it becomes one of the most affordable ways to achieve supercomputing power unlimitedly if the appropriate parallel algorithm and the operating program are developed for this slow network environment. Under the above concept, virtual supercomputing system InterSup I is constructed and tested. To establish the InterSup I system, 64 CPU nodes, which are located in several places and connected by Internet, are conscripted, and parallel finite element software is developed for linear static analysis of structures based on the parallel multi-frontal algorithm. By the established InterSup I system, analysis of finite element structural model having around five million DOFs are solved to check the affordability and effectiveness of Internet Supercomputing.

• Journal of Power Electronics
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• 제15권1호
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• pp.116-122
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• 2015

This paper presents a new current sharing control strategy for parallel-connected, synchronised three-phase DC-AC converters employing space vector pulse width modulation (SVPWM) without current sharing reactors. Unlike conventional control methods, the proposed method breaks the paths of the circulating current by dividing the switching cycle evenly between parallel connected equally rated converters. Accordingly, any inter-module reactors or circulating current control will be redundant, leading to reductions in system costs, size, and control algorithm complexity. Each converter in the new scheme employs a synchronous dq current regulator that uses only local information to attain a desired converter current. A stability analysis of the current controller is included together with a simulation of the converter and load current waveforms. Experimental results from a 2.5kVA test rig are included to verify the proposed control method.

• Journal of Electrical Engineering and Technology
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• 제6권4호
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• pp.466-473
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• 2011

This paper proposes a protection algorithm for a wind turbine generator (WTG) in a large wind farm. To minimize the outage section, a protection relay for a WTG should operate instantaneously for an internal fault or a connected feeder fault, whereas the relay should not operate for an internal fault of another WTG connected to the same feeder or an adjacent feeder fault. In addition, the relay should operate with a delay for an inter-tie fault or a grid fault. An internal fault of another WTG connected to the same feeder or an adjacent feeder fault, where the relay should not operate, is determined based on the magnitude of the positive sequence current. To differentiate an internal fault or a connected feeder fault from an inter-tie fault or a grid fault, the phase angle of the negative sequence current is used to distinguish a fault type. The magnitude of the positive sequence current is then used to decide either instantaneous operation or delayed operation. The performance of the proposed algorithm is verified under various fault conditions with EMTP-RV generated data. The results indicate that the algorithm can successfully distinguish instantaneous operation, delayed operation, or non-operation depending on fault positions and types.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.234-236
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• 2002

The Co-Gen System which maximize energy efficiency was installed at the industrial plants at the initial stage. However Small Scale Co-Gen System was expanded even to the general end-users such as housing and building owing to ESCO business recently. For this SSC, inter-connected operation to the utility is desirable due to voltage and frequency fluctuation following to unbalance between power output and load. Then voltage unbalance with utility system, frequency, increase of short circuit capacity, reclosing, and ALTS etc. should be fully considered for the inter-connected operation. Voltage variation, protection coordination, Co-Generators single running, and short circuit capacity should also be solved. To research the method and solve the problems through the field test and application, we study individual customers Co-Gen System as a case study.

• Earthquakes and Structures
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• 제4권6호
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• pp.649-670
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• 2013

It is known that a base-isolated building exhibits a large response to a long-duration, long-period wave and an inter-connected system without base-isolation shows a large response to a pulse-type wave. To compensate for each deficiency, a new hybrid passive control system is investigated in which a base-isolated building is connected to another building (free wall) with oil dampers. It is demonstrated that the present hybrid passive control system is effective both for pulse-type ground motions and long-duration and long-period ground motions and has high redundancy and robustness for a broad range of disturbances.

• 한국항만학회지
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• 제5권1호
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• pp.29-54
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• 1991

In this study, to identify the ineffectiveness of inter-connected system of cargo volume between the Pusan Port and inland areas and also to make more rational suggestions, the following conclusions were drawn by analyzing Container Cargo Traffic from BCTOC to Off-Dock CY: 1. There existed about 30% to 50% reduction in the container transport times when the container transport vehicles were operated during the off-peak period to alleviate the traffic congestion due to mixed traffic. 2. There appeared to be more economic when Off-Dock DY's scattered around the City of Pusan were unified in one ODCY Unit at YangSan, and the Exclusive Overpass Freeway System for the container transport vehicles were constructed and operated on the existing Urban Freeway from BCTOC ti this ODCY Unit (Expected to make about 230 billions Won in net present value by NPV method).

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.299-302
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• 2000

In this paper, a Inter-Working Function Unit(IWF) has been developed and designed in order to change to advanced subscriber system the Remote Subscriber System(RSS) that is operating with simple services(PSTN Function only). Regarding the cost and the effectiveness, RSS should be connected to Access Subscriber System with PCM cables directly. As this method being used, in the period of Retrofit, the connecting job covering RSS will be handled easily and safely.