• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.288-290
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• 2005

고분자전해질 연료전지는 자동차, 분산전원 및 이동전원 등에 대한 차세대 에너지원으로 채택 가능성이 높아지고 있다. 고분자전해질 연료전지 시스템의 상용화를 위한 가장 큰 걸림돌 중 한 가지로 가격문제를 들 수 있는데, 연료전지 스택이 전체 가격의 약 $50\%$를 차지하고 있다. 또한 스택을 구성하는 요소 중 분리판의 가격 비중은 약 $30\%$를 차지하고 있어, 분리판의 생산단가 저감은 연료전지의 상용화를 위해 반드시 해결해야 될 문제이다. 본 연구에서는 탄소를 재료로 하는 분리판에 대한 연구를 수행하였으며, 압축성형방식으로 제작된 다양한 복합재료 분리판 및 흑연 분리판에 대한 기계적 강도, 물리적 특성, 화학적 안정성을 조사하였으며, 가흑 운전 시 분리판내에 함유되어있는 고분자 성분의 침출에 의한 연료전지의 성능변화가 발생하는지 확인하였으며 이에 대한 단위전지의 성능평가를 수행하였다. 이러한 결과를 토대로 최적의 압축성형 복합체 분리판 제작 방향을 제시하고, 보다 신뢰성 있는 분리판 성능평가 기준을 확립하고자 하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10c
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• pp.93-97
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• 2006

센서 네트워크에서 질의 처리 기술은 통신 비용을 절감하고 신뢰성을 향상하고 에너지 효율성을 향상시키는데 목적을 두고 있다. 현재 에너지의 효율성을 위해서 센서 노드가 수행하는 질의를 최적화하여 전력 손실을 줄이고자 하는 연구가 활발하게 수행 중이다. 본 논문에서는 실체 뷰와 인덱싱 뷰를 이용하여 센서 네트워크에 맞는 효율적인 새로운 센싱 뷰라는 기법을 제안한다. 제안하는 질의 처리 알고리즘은 실체 뷰와 인덱싱 뷰의 개념을 바탕으로 기존의 분산 데이터베이스의 질의 처리 방법을 센서 네트워크에 적용하였다. 제안된 센싱 뷰 알고리즘은 센싱 뷰를 싱크 노드에 위치시킴으로서 센서 노드와의 통신 횟수를 최대한 줄임으로서 통신 비용과 에너지의 소모량을 줄일 수 있었다. 성능은 시뮬레이션을 통해서 평균적으로 약 30%정도의 성능 향상 효과를 보였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.581_582
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• 2009

최근 국내외적으로 스마트그리드, 마이크로그리드와 같은 곧 다가올 미래형전력계통망에 대한 기반기술연구가 매우 중요하다. 이는 전력IT기술과도 깊은 관련성이 있는 것으로써 그 성공여부는 전력IT기술과 협조를 맺으면서 여하히 기술적으로 이를 실현화(Implementation)하는냐에 달려있다고 하겠다. 본 연구에서는 최근 국내외적으로 급부상하고 있는 스마트그리드 마이크로그리드와 같은 곧 다가올 미래형전력계통망에 대비하고 나아가 $CO_2$ 감축의무와 맞물려 있는 분산형 신재생에너지발전원의 계통병입이 전력에너지의 적정공급신뢰도에 미치는 영향을 정량적으로 분석할 수 있는 웹기반 확률론적인 신뢰도 및 발전비용모의를 인터넷의 사용이 가능한 곳이면 어느 장소 및 시간대(Any where & any time)에서나 실시할 수 있는 시스템인 가칭, WPRASS V1.0(Web based Probabilistic Reliability Assessment Simulation System V1.0)을 성공적으로 구축하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.585-588
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• 2007

As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This new generation technology is linked to a large number of factors like economics and performance, safety and reliability, market regulations, environmental issues, or grid connection constrains. KEPCO (Korea Electric Power Corporation) is performing the project to develope the Distributed Micro Gas Turbine (MGT) technolgies by using Swine BIO-ENERGY. This paper describes the plans and strategies for the renewable energy of MGT on actual grid-connection under Korean situations. KEPCO also, has a research plan on bio-gas pretreatment system applicable to our domestic swine renewable resources and is performing concept design of pilot plant to test grid operation. In addition, this testing will be conducted in order to respond to a wide variety of needs for application and economic evaluation in the field of On-site generation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.2
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• pp.49-59
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• 2000

Wave distribution in Jangjeon Harbour is numerically simulated for an optimum design of the harbour facilities. A deep-water design wave is estimated based on stochastic extreme wave analysis of wind data in the vicinity of the harbour, and it is applied to the boundary condition at open sea. Boussinesq wave theory that includes effects of frequency dispersion and nonlinearity is employed for the wave simulation. The porosity and sponge layer are adapted at beach to depict partial reflection and complete absorption of waves, respectively. The design wave for breakwater is computed in global domain with coarse grids and the wave distribution inside of wharf is simulated in local domain with fine grids.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.3
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• pp.206-210
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• 2009

In this paper, we propose a new routing scheme based on multi-path routing which provides uniform energy consumption for all nodes. This scheme adds a new type of root node for constructing multi-path. The sink node delegates some partial roles to these root nodes. Such root nodes carry out path establishment independently. As a result, each nodes consume energy more uniformly and the network life-time will be extended. Through simulation, we confirmed that energy consumption of the whole network is scattered and the network life-time is extended. Moreover, we show that the proposed routing scheme improves the performance of network compared to previous routing strategies as the number of source nodes increases.

• Journal of the Korean Chemical Society
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• v.23 no.4
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• pp.210-216
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• 1979

A simple method to calculate the interfacial tension between two immiscible molten polymers has been developed. The theory is based on the significant structure theory of liquids. The energy of adhesion is expressed as a geometric mean of the cohesion energies multiplied by correction factor $({\Phi}12)$, ${\Delta}E_{12}={\Phi}_{12}\sqrt{{\Delta}E_{11}{\Delta}E_{22^{\circ}}$. In the calculation of ${\Delta}E_{11}\;and\;{\Delta}E_{22}$, a quasilattice of polymer chains has been assumed. It is assured that, besides the dispersion force, the polar force interactions between polymer constituent groups should be considered in the calculation of the interfacial tensions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.535-538
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• 2010

In this paper, this study goal is development for WSN-based fire prevention systems of using temperature/humidity Sensor. So, distributed sensor nodes structural and packet transfer characteristics study for fire monitoring. Battery-operated wireless sensor networks is data transfer manner of multi-hop. WSN fire prevention system need to sensor nodes management and energy consumption of efficient adjust for sustained action. Thus, study with efficient energy consumption the normal WSN environment is not, characteristics for WSN fire prevention environment.

• Transactions of the Korean hydrogen and new energy society
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• v.7 no.2
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• pp.129-135
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• 1996

Voltage-current profiles are measured when hydrogen-oxygen gas is in contact with solid polymer membrane ($Nafion^{(R)}$) as the electrolyte. The feed gas is prepared by mixing hydrogen and oxygen gas in various ratios. The carbon gas diffusion electrodes contacting the electrolyte are treated by platinum catalyst. The platinum surface is impregnated with a 5% $Nafion^{(R)}$ solution to ensure its good surface contact with the electrolyte. The constant voltage between anode and cathode was applied by a DC power supply. The results on the profiles show that the energy efficiency critically depends on the hydrogen concentration in $H_2/O_2$ mixture gas.

• New & Renewable Energy
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• v.9 no.2
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• pp.51-57
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• 2013

The Grid code is being strengthen as increase of renewable energy ratio. Especially, the grid connection regulations are continuously being updated for stable operation of power grids. Static grid support and Dynamic grid support must make an accurate measure at Grid connected point because they needs control algorithm individually. It has to exactly measure voltage including switching ripple at the output of the inverter generating system. In addition, it is necessary to have an accurate voltage measurement when the situation rapidly changing the grid impedance is caused by the input of serial impedance of transformer and line impedance as well as Grid Fault Device. In this paper, We propose a new detection method of grid voltage to calculate accurately the r.m.s voltage of the grid connection point along the standard required by the low voltage regulation. We verified performance through simulation grid fault device.