• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.36.1-36.1
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• 2011

풍력개발 기술이 발전함에 따라 풍력발전시스템이 점차 대용량화되는 추세이며, 경제성 있는 풍력단지 건설을 위해 점차 대단지화 되어가고 있는 실정이다. 이로 인해 풍력 발전단가(Cost of electricity, COE)도 개선되고 있다. 풍황이 양호한 풍력발전단지의 경우, 풍력발전 COE는 현재 50~60원/kWh 수준으로 타 신재생에너지원에 비해 경쟁력이 높고, 석탄 화력의 COE와 비교해 봐도 동등한 수준 혹은 더욱 경쟁력 있는 수준으로 감소하였다. 풍력발전단지 조성을 위해서는 시스템의 효율과 고효율, 저비용의 풍력발전시스템을 풍황이 좋은 지역에 설치할 때 낮은 COE를 가지는 경제성 있는 발전단지가 가능하다. 동급 용량 풍력발전시스템을 같은 지역에서 설치하여 에너지생산량을 증대시키기 위해서는 블레이드 지름의 증가시켜 유량을 증가시키거나 타워의 높이를 증가시켜 풍속을 증가시키는 방안이 있다. 이 경우 블레이드 길이와 타워 높이 증가에 의한 시스템 비용의 증가가 발생하는데, 에너지생산량 증가에 의한 수익비용과 시스템 비용 증가에 의한 자본비용은 서로 반비례로 영향을 미친다. 이를 위해 최소의 COE의 최대의 순현재가치(Net Present Value, NPV)를 갖는 목적함수로 두고 블레이드의 최적 길이와 타워의 최적 높이를 선정하였다.

• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.54-65
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• 2006

This study was conducted to examine the biomass and energy content of 60- to 70-year-old Quercus mongolica stand facing northern and southern aspect in Mt. Baekwoon (800 m above sea level), Gwangyang, Jeollanam-do and in Mt. Halla (1,000 m above sea level), Jeju-do. The total biomass was 288.4 ton/ha in northern aspect and 241.9 ton/ha in southern aspect of Mt. Baekwoon while 368.4 ton/ha in northern aspect and 364.3 ton/ha in southern aspect of Mt. Halla. Annual net production was 20.7 ton/ha/yr in northern aspect and 17.7 ton/ha/yr in southern aspect of Mt. Baekwoon while 19.0 ton/ha/yr in northern aspect and 21.2 ton/ha/yr in southern aspect of Mt. Halla. Total biomass and annual net production of Mt. Halla were greater than those of Mt. Baekwoon. The net assimilation rate (NAR) was 5.05 in northern aspect and 4.09 in southern aspect of Mt. Baekwoon, while 4.60 in northern aspect and 3.66 in southern aspect of Mt. Halla, Total energy content was 5,666 GJ/ha in northern aspect and 4,793 GJ/ha in southern aspect of Mt. Baekwoon while 6,550 GJ/ha in northern aspect and 6,435 GJ/ha in southern aspect of Mt. Halla. Annual energy content was 365 GJ/ha/yr in northern aspect and 360 GJ/ha/yr in southern aspect of Mt. Baekwoon while 351 GJ/ha/yr in northern aspect and 347 GJ/ha/yr in southern aspect of Mt. Halla. Annual energy content of Mt. Baekwoon was greater than that of Mt. Halla.

• Journal of Korean Society of Forest Science
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• v.95 no.3
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• pp.309-315
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• 2006

This study was to compare the biomass and annual net production between 60 to 70-year-old Quercus mongolica stand facing northern and southern aspect in Mt. Joongwang (1000 m from sea level), Pyungchang and 35-year-old Q. mongolica stand in Mt. Wolak (300m from sea level), Jechon. The total biomass was 252.9 ton/ha in northern aspect and 212.2 ton/ha in southern aspect of Mt. Joongwang while 198.7 ton/ha in northern aspect of Mt. Wolak. Annual net production was 17.3 ton/ha/yr in northern aspect and 14.2 ton/ha/yr in southern aspect of Mt. Joongwang while 21.2 ton/halyr in Mt. Wolak. Total biomass, especially leaf and branch biomass in north slope was greater than those in south slope of Mt. Joongwang. Leaf area index (LAI) of Q. mongolica stand was 11.17 in Mt. Wolak while 5.77 in northern aspect and 3.97 in southern aspect of Mt. Joongwang, and the net assimilation rate (NAR) was 2.60 kg/kg/yr, 4.26 kg/kg/yr, 6.06 kg/kg/yr in same order.

• Nuclear Engineering and Technology
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• v.43 no.2
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• pp.99-104
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• 2011

A Structure Health Monitoring (SHM) system needs a real-time remote data acquisition system to monitor the status of a structure from anywhere via Internet access. In this paper, we present a data acquisition system that monitors up to 40 Fiber Bragg Grating Sensors remotely in real-time. Using a TCP/IP protocol, users can access information gathered by the sensors from anywhere. An experiment in laboratory conditions has been done to prove the feasibility of our proposed system, which is built in special-purpose monitoring system.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.237_238
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• 2009

This paper proposes coordinative control method between STATCOM installed within substation and other reactive power resources including Shunt Reactors and Shunt Capacitors and OLTC. Voltage/Reactive power control has various difficult aspects to control because of analysis and system dynamics error. This coordinative control method suggests practical algorithm regarding system voltage and reactive power status which is easy to implement in substation basis. In normal status, STATCOM-Shunts-OLTC are in operation. The proposed algorithm is tested and verified in EMTP/RV. And this is expected to be applied to control multiple reactive power devices combined with SCADA/EMS system.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.01a
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• pp.43-44
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• 2015

본 논문에서는 Run & Jump 모바일 게임을 설계하고 구현한다. 이 게임은 다양한 동물 캐릭터가 달리면서 장애물을 피하고, 별 아이템을 획득하기 위해 점프하여 점수를 획득하는 게임이다. 이 게임의 특징은 XNA Framework를 사용하여 메인화면과 도움말, 게임중 일시정지, 다양한 동물 케릭터 선택 등의 기본 기능을 구현한다. 또한 게임실행 로직, BGM, 효과음, 사운드 켜기 끄기 기능을 구현한다. 그리고 별 아이템 획득 및 장애물를 피하면서 얻는 점수를 DB에 저장하여 관리하는 ranking 시스템을 구현한다.

• Nuclear Engineering and Technology
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• v.40 no.6
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• pp.505-510
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• 2008

The correlation between the tensile strength and corrosion behavior of Zr-1.0wt%Nb alloy heat treated at $480^{\circ}C$ for up to 32 hours was evaluated. The tensile strength at $400^{\circ}C$ was continuously reduced with an increasing heat treatment time, mainly due to a grain growth and a decreased area fraction of the precipitates. However, the corrosion resistance in an aqueous ammonia solution at $360^{\circ}C$ was enhanced, mainly due to the formation of $\beta$-Nb precipitates. It is thus concluded that a longer heat treatment time provides a better corrosion resistance while degrading the tensile strength.

• Journal of the Korea Safety Management & Science
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• v.11 no.3
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• pp.181-188
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• 2009

This paper presents the economic validity with the cost/benefit analysis on establishing R&D Supreme Academy. To evaluate the profitability of R&D Supreme Academy, willingness to pay (WTP) is measured by contingent valuation method (CVM) and then the net present value (NPV), internal rate of return (IRR) and benefit/cost ratio(BCR) are calculated. The results of economic evaluation verified that the establishment of R&D Supreme Academy is timely and effective in an economic perspective.

• Journal of Hydrogen and New Energy
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• v.21 no.3
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• pp.184-192
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• 2010

PEM fuel cell produces electric power, water and heat by the electrochemical reaction of hydrogen and oxygen. The heating value is dependent on the molar enthalpy of vaporization of product water and the performance loss. In this paper, the heating value of fuel cell stack has been studied under various stack operating temperatures to achieve more efficient heat management. A technology using the molar enthalpy of vaporization of product water is suggested to reduce heat-up time during start-up of a fuel cell vehicle.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.267-268
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• 2014

본 논문에서는 XNA Framework 기반의 모바일 게임을 설계하고 구현한다. 이 모바일 게임의 특징은 스토리, 이미지, 단계별 맵 클리어, 장애물 등의 4개 요소를 고려하여 개발한다. 바다에 등장하는 다양한 캐릭터를 사용하였으며 메인 캐릭터가 단계별 맵에서 주어진 아이템을 획득하면 해당 맵이 클리어 되고 다음 단계로 진행되도록 구현한다. 전통적인 게임, 흥미 외에도 메인 캐릭터가 경로를 찾는 방법과 게임에 생명을 주는 알고리즘을 구현한다.