• 한국수소및신에너지학회논문집
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• 제27권4호
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• pp.341-348
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• 2016

The experiments related on structure and water electrolysis performance of HALE UAV stack were conducted in this study. Anode catalyst $IrRuO_2$ was prepared by Adam's fusion methods as 2~3 nm nano sized particles, and the cathode catalyst was used as commercial product of Premetek. The MEA (membrane electrode assembly) was manufactured by decal methods, anode and anode catalytic layers were prepared by electro-spray. HALE stack was composed of 5 multi-cells as $0.2Nm^3/hr$ hydrogen production rate with hydrogen pressure as 10 bar. The water electrolysis performance was investigated at atmospheric pressure and temperature of $55^{\circ}C$. Best performance of HALE UAV stack was recorded as cell voltage efficiency as 86%.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권1호
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• pp.66-71
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• 2018

Purpose: Performance recovered from SCR through cleaning was studied, measuring differential pressure, NOx reduction efficiency, fuel consumption and engine power before and after cleaning. Ideal cleaning intervals are proposed based on SCR mileage and differential pressure. SCR endurance and reliability improvements through cleaning were studied through physicochemical testing of SCR durability at 43,000km 50,000km, and 110,000km respectively. Methods: Engine power, fuel consumption and exhaust gas were measured using engine full load tests and ND-13 MODE by installing the SCR before cleaned at total engine mileages of 400,000 km, 300,000km and 200,000km. The same tests were performed after cleaning the SCR catalytic converter. Endurance and reliability of the SCR cleaning was studied through the same test by SCR catalyst after each 43,000km 50,000km, 110,000km, durability test on SCR cleaning. Conclusion: We confirmed the low-performance of the SCR due to clogging is restored by SCR cleaning technology. The NOx reduction efficiency was restored to 82%, 86% and 88% from 69%, 72% and 79%. As well as the NOx reduction efficiency, it was confirmed that the engine power, fuel consumption and back pressure was restored to fresh SCR levels. As a result of the durability and reliability achieved through SCR cleaning, we confined the appearance and reduction efficiency through visual inspection and ND-13 MODE are similar to new SCR catalysts. Finally, it was judged that there was no change in performance even when driving the SCR without cleaning throughout the 100,000 km mileage warranty.

• 한국식품영양과학회지
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• 제32권7호
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• pp.1076-1081
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• 2003

근육은 지속적인 수축운동 과정상에서 근육 세포내의 에너지원인 ATP가 고갈되고, 근육피로를 나타내는 물질이 축적되어 근력이 약해지고 피로도가 증가하게 된다. 지구력을 향상시키기 위하여 ATP의 합성 증가 및 근육내 피로 물질의 축적 방지 등이 요구되어지는데, 본 연구에서는 전통 생약재로부터 추출 증류한 조성물 JR-22를 이용하여 지구력 향상 효과를 확인하고자 하였다. JR-22를 4주간 실험 동물에게 투여한 이후 체중의 4-8%에 해당하는 무게를 부가하고 강제수영 시간을 통하여 지구력 향상효과를 확인한 결과 JR-22의 투여로 인하여 지구력이 향상되는 효과를 확인하였다 JR-22에 의한 지구력 향상효과의 기작을 관찰하기 위하여 체중의 4%에 해당하는 무게를 부가한 뒤 90분간 강제 수영시킨 실험 동물로부터 근육 피로 물질들과 근육내 ATP 함량을 측정한 결과 JR-22의 투여가 근육내 ATP 함량을 증가시키는 것으로 나타나 JR-22의 투여가 근육내 ATP를 증가시킴으로서 지구력을 향상시키는 효과를 나타내는 것으로 추측되었다. 또한 근육세포의 강화와 연관성이 있는 IGF-1과의 관련성을 알아보기 위하여 JR-22를 투여한 이후 혈액중의 IGF-1의 농도를 측정하였을 때도 JR-22에 의해서 유의성이 있는 IGF-1의 증가가 관찰되어 JR-22의 투여가 근력 강화에 도움을 줄 수 있다고 추측되었다. 이러한 운동 과정상에서 발생하는 체내의 산화적 손상은 JR-22의 투여를 통해 완화되고 있음을 확인하여 JR-22의 투여가 체내의 항산화력 증진에 도움을 줄 수 있는 것으로 추측되었다. 한편 JR-22를 4주 이상 투여하였을 경우에도 간독성 지표인 GOT, GPT를 비롯한 각종 혈액 생화학적 수치들의 변화가 나타나지 않았으며, 기타 이상 소견이 발견되지 않아 JR-22의 식용으로서의 안전성에도 문제가 없는 것으로 판단되었다. 이상의 결과에서 JR-22는 IGF-1의 증가 및 근육내 ATP 농도를 증가시킴으로서 지구력을 강화시키는 효과가 있을 뿐 아니라 운동시 발생하는 부작용중 하나인 산화적 손상을 억제시키는 항산화 효과 또한 겸비하고 있는 것으로 판단된다.

• Journal of Electrochemical Science and Technology
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• 제7권1호
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• pp.41-51
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• 2016

In the stratosphere, the air is stable and a photovoltaic (PV) system can produce more solar energy compared to in the atmosphere. If unmanned aerial vehicles (UAVs) fly in the stratosphere, the flight stability and efficiency of the mission are improved. On the other hand, the weakened lift force of the UAV due to the rarefied atmosphere can require more power for lift according to the weight and/or wing area of the UAV. To solve this problem, it is necessary to minimize the weight of the aircraft and improve the performance of the power system. A regenerative fuel cell (RFC) consisting of a fuel cell (FC) and water electrolysis (WE) combined PV power system has been investigated as a good alterative because of its higher specific energy. The WE system produces hydrogen and oxygen, providing extra energy beyond the energy generated by the PV system in the daytime, and then saves the gases in tanks. The FC system supplies the required power to the UAV at night, so the additional fuel supply to the UAV is not needed anymore. The specific energy of RFC systems is higher than that of Li-ion battery systems, so they have less weight than batteries that supply the same energy to the UAV. In this paper, for a stratospheric long-endurance hybrid UAV based on an RFC system, three major design factors (UAV weight, wing area and performance of WE) affecting the ability of long-term flight were determined and a simulation-based feasibility study was performed. The effects of the three design factors were analyzed as the flight time increased, and acceptable values of the factors for long endurance were found. As a result, the long-endurance of the target UAV was possible when the values were under 350 kg, above 150 m² and under 80 kWh/kg H₂.

• 한국체육학회지인문사회과학편
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• 제55권3호
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• pp.649-658
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• 2016

본 연구는 지구성 트레이닝과 thiamine(thiamine tetrahydrofurfuryl disulfide: TTFD)의 투여가 골격근 내 글리코겐과 PDH(Pyruvate dehydrogenase), 그리고 PDH 활성에 관여하는 효소의 단백질인 PDK4(Pyruvate dehydrogenase kinase 4)와 PDP1(PDH phosphatase 1)의 발현에 어떠한 영향을 미치는지 알아보는 것을 목적으로 하였다. 6주령의 ICR 마우스를 대상으로 비운동집단(Sedentary; CON, TH), 운동집단(Exercise; EX, THEX)으로 나누어 4주간의 지구성 트레이닝과 체중 kg 당 50 mg의 thiamine을 경구투여 하였다. 4주간의 지구성 트레이닝은 간과 근육 내 glycogen의 저장량에 유의한 증가가 나타났지만 thiamine 투여에 따르는 차이는 나타나지 않았다. 마찬가지로 골격근 내 PDH와 PDH 조절에 관련한 PDK4, PDP1의 단백질 발현을 측정한 결과 4주간의 지구성 트레이닝에 따르는 효과는 관찰되었지만, thiamine 투여에 집단간 유의한 효과는 나타나지 않았다. 이러한 결과는 장기간 지구성 트레이닝에 따른 골격근의 적응으로 인하여 thiamine 투여에 따른 시너지 효과가 나타나지 않은 것으로 보인다. 따라서 추후 연구에서는 지구성 트레이닝의 기간을 고려한 thiamine의 섭취 타이밍 그리고 탄수화물의 복합투여에 따른 PDH와 관련 단백질의 분석이 필요할 것으로 보인다.

• 한국자동차공학회논문집
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• 제24권2호
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• pp.232-241
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• 2016

The turbocharger, to decrease the harmful exhaust gas(CO, HC and etc.) and $CO_2$ emission as well as the increase of the engine output, would be an useful method for engine downsizing. Therefore the thermal endurance of turbine blade, the lubrication of turbine shaft and the engine knock according to the supercharge of the inlet air, had been studied. And there had been much progress in these research tasks to be achieved a breakthrough. But a study on the built-in WGV of a gasoline engine for a passenger car which may effect on the engine performance, is few. In this paper, the effect of the embedded WGV on the engine performance was performed through the endurance test, which was conducted more than 300 hrs using the 4 stroke, 1998 cc, water-cooled engine. To sum up the major results, there were an abrasion in the area of the WGV head edge and the thermal deformation on the WGV head face, These phenomena led to reducing the boost pressure which caused the reduction in the volumetric efficiency of the engine. It resulted in decreasing the engine power gradually during the life cycle of the embedded WGV.

• Journal of the Korean Wood Science and Technology
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• 제32권5호
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• pp.66-74
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• 2004

내화 성능은 표준 화염 조건에 노출된 목구조물의 안전성 평가를 위한 중요한 기준이 된다. 내화 성능의 기준으로 여러 나라에서 지속 시간과 파괴 시까지의 시간이 사용되고 있다. 본 연구에서는 화염에 대한 신뢰성 설계의 기초 연구로서 화염에 노출된 목재 마루 시스템의 신뢰성 해석이 진행되었다. 해석은 수치 해석적 방법과 결정론적 방법 두 가지를 모두 사용하였다. 두 방법 간에는 큰 차이를 보이지 않았다. 화염에 노출된 마루시스템의 신뢰도는 부재의 변이계수에 크게 의존하였으며 부재의 강도나 하중은 신뢰도에 크게 영향하지 않았다.

• 한국항공운항학회지
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• 제24권4호
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• pp.35-43
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• 2016

UAV has been promoted for practical use in the field of civilian and military. Recently, UAV is required high-specification performance such as long-term flight and precision observation. Among these UAVs, High Altitude Long Endurance UAV(HALE UAV) has been developed for the purpose to replace some of the functions of the satellite such as meteorological observation, communications and internet relay while flying a long period in the stratosphere. In order to fly a long period in harsh environment of the stratosphere, aircraft needs high Lift-Drag-Ratio and weight reduction of the structure. This paper performed the structural analysis for fuselage and empennage of HALE UAV. Critical loading conditions for structural analysis are acquired from flight load analysis and finally the results of structural sizing for weight reduction is presented.

• 대한임베디드공학회논문지
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• 제11권2호
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• pp.87-95
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• 2016

Nonvolatile memory (NVM) is being considered as an alternative of traditional memory devices such as SRAM and DRAM, which suffer from various limitations due to the technology scaling of modern integrated circuits. Although NVMs have advantages including nonvolatility, low leakage current, and high density, their inferior write performance in terms of energy and endurance becomes a major challenge to the successful design of NVM-based memory systems. In order to overcome the aforementioned drawback of the NVM, extensive research is required to develop energy- and endurance-aware optimization techniques for NVM-based memory systems. However, researchers have experienced difficulty in finding a suitable simulation tool to prototype and evaluate new NVM optimization schemes because existing simulation tools do not consider the feature of NVM devices. In this article, we introduce a NVM-based cache simulator to support rapid prototyping and evaluation of NVM-based caches, as well as energy- and endurance-aware NVM cache optimization schemes. We demonstrate that the proposed NVM cache simulator can easily prototype PRAM cache and PRAM+STT-RAM hybrid cache as well as evaluate various write traffic reduction schemes and wear leveling schemes.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.887-888
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• 2006

The present study describes the wear and mechanical behaviour of carbide composites in cyclic loading applications (blanking of sheet metal). Adhesive wear as well as fatigue endurance were tested, complemented by XRD studies. It was found that the blanking performance of a carbide composite is controlled by its resistance to adhesion wear and fatigue sensitivity. XRD studies revealed that fatigue damage is preceded by plastic strain in both phases of the composites