• International Journal of Air-Conditioning and Refrigeration
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• 제16권4호
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• pp.124-129
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• 2008

Design practice has been made on an oil-less scroll air compressor as an air supply device for a 2 kW fuel cell system where air pressure of 2 bar and flow rate of 120 liter/min are required. Basic structure of the scroll compressor includes double-sided scroll wrap for the orbiting scroll driven by two crankshafts connected to each other by a timing belt. These features can eliminate thrust surface which otherwise would produce frictional heat and jeopardize reliable operation of the orbiting scroll and the scroll element's deformation as well. This study focuses on optimum scroll wrap design; orbiting radius has been chosen as an independent design parameter. As the orbiting radius changes, scroll sizes such as scroll base plate and discharge port diameters change accordingly. Gas compression-related losses and mechanical loss also change with the orbiting radius. With a scroll base plate diameter of 120mm at most and discharge port of at least 10mm, the orbiting radius should be within the range of 2.5-4.0mm. With this range of the orbiting radius, it was estimated by performance analysis that the compressor efficiency reached to a maximum of ${\eta}_c$=96% at the orbiting radius of $r_s$=3.5mm for the scroll wrap height-to-thickness ratio of h/t=5.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1135-1138
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• 2003

The transformer is major equipment in power receiving and substation facilities. Necessary conditions required for the transformer are compactness, lightness, high reliability, economic advantages, and easy maintenance. The pole-mount transformer installed in distribution system is acting direct role in supply of electric power and it is electric power device should drive for long term. Most of modem transformer are oil-filled transformer and accident is happening considerable. The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. One body molding transformer needs some cooling method because heat radiation between each winding is difficult. In this paper, The thermal analysis of pole mount mold transformer with one body molding by duct condition is investigated and the test result of temperature rise is compared with simulation data.

• 한국기계기술학회지
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• 제13권3호
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• pp.107-111
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• 2011

This carbon nano heating system was consisted of power supply equipment, a carbon fiber and a stainless flexible hose. carbon nano heating system was manufactured by carbon fiber of a power capacity 30kw/h and light-oil hot air heater in control plot was the heating capacity 30,000kcal/h, As the result, Temperature difference due to carbon nano heating system and hot air heater in greenhouse showed that air temperature at experimental greenhouse, comparison greenhouse were $14.8^{\circ}C$, $13.4^{\circ}C$ respectively. It was found that carbon nano heating system and light-oil hot air heater heating cost were 1,095,740won, 2,683,628won. therefore as heating cost saving 60%. Yield of tomatoes cultured in greenhouse using carbon nano heating pipe was 4% inclease. Economic analysis comparison between the carbon nano heating pipe and the hot air heater in greenhouse were 41% respectively.

• 드라이브 ㆍ 컨트롤
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• 제18권3호
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• pp.1-7
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• 2021

In a hydraulic control system, since a hydraulic cylinder drives a relatively large mass of an object, an external load force acts as a disturbance on the control performance of the system. Additionally, as the hydraulic system is used for a long period, there are disturbances that occur gradually, such as a drop in supply pressure because of abrasion of the pump, oil leakage from a valve, and oil leakage from a cylinder. In this study, a state feedback controller based on a linearization technique is applied. To prevent the performance degradation of the controller from the load disturbance, an Extended Luenberger observer (ELO) is used for the Extended system. The case of using the proportional controller, which is a representative linear controller, and the result of using the controller designed in this study are compared and reviewed through simulation. Also, we propose an experimental gain-setting method for a state feedback controller that can be used at industrial sites, and examine how the stability and control performance of the system changes because of the disturbance inputs through the experimental results.

• 한국산학기술학회논문지
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• 제19권7호
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• pp.9-15
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• 2018

본 연구에서는 터보과급기의 성능을 저해하는 주요 인자 중 하나인 마찰손실에 대한 연구를 수행하였다. 실제 엔진에서 빈번하게 사용되는 저속 구간에서의 승용차용 터보과급기의 마찰손실 측정 장치를 개발하고, 저속 영역에서 작동하는 터보과급기의 마찰손실을 측정하였다. 플로팅 타입의 승용차용 터보과급기 저널 베어링를 실험 대상으로 선정하였으며, 마찰손실 측정 장치는 구동 모터, 오일 공급 시스템, 마그네틱 커플링으로 구성하였다. 실제 차량의 저속 운전 상황을 모사할 수 있도록 설계, 제작되었고, 터보과급기 회전속도, 오일 온도 및 압력을 실험 변수로 선정하였다. 또한, 마찰손실 측정 장치는 로드 셀을 사용하여 발생하는 마찰 토크를 직접 측정하여 마찰손실을 산출하였으며, 커플링을 통해 구동 모터의 동력을 터보과급기 축에 전달하고, 오일 온도 및 압력을 조절하였다. 오일 압력 3bar와 4bar로 오일을 공급하는 상태에서 오일 온도를 $50^{\circ}C$에서 $100^{\circ}C$까지 $10^{\circ}C$ 간격으로 변화시키면서 터보과급기를 회전수 30,000~90,000rpm으로 작동시켰다. 터보과급기 회전속도 증가할 때 마찰손실은 증가하였으며, 과급기 회전속도의 1.6 승에 비례함을 보였다. 오일 온도가 증가함에 따라 마찰손실은 감소하였으며, 오일 압력이 증가함에 따라 마찰손실은 증가하였다. 따라서 적절한 오일 온도와 압력을 유지하는 것이 필요하다.

• 한국항만경제학회지
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• 제39권1호
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• pp.149-172
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• 2023

한·중·일을 포함하는 동북아지역은 1990년대 이후 급속한 경제성장과 더불어 역내외 석유물류가 증대되고 있다. 우리나라는 이러한 대외적인 환경하에서 2000년대 중반 이후 동북아 석유물류허브화 정책을 추진해 왔다. 동북아 물류허브화를 위해서는 부가가치 석유물류의 비즈니스 활성화를 위한 비즈니스 모델의 구축과 촉진이 중요하다. 동북아 지역에서 우리나라 석유물류 비즈니스 모델을 분석함으로써 석유물류 활성화에 대한 정책적·실무적 시사점을 제시하는 데 목적이 있다. 전체 23개 탱키지 업체를 대상으로 면담조사에 의한 사례분석결과는 다음과 같다. 첫째, 면담조사한 대부분의 유류저장탱크터미널업체들은 블랜딩, 소분화, 집적화와 같은 부가가치 석유물류를 실시하고 있다. 둘째, 부가가치 석유물류의 발생은 주변국들간 수급의 불균형에 의해 발생하고 있는데 특히 일본, 오세아니아, 미국, 남미 등을 연결하는 소분화와 블랜딩 수요가 높다. 셋째, 부가가치 물류수요에 대응한 인프라, 제도 및 규제 등에 대한 개선을 통해 부가가치 석유물류의 활성화를 촉진해야 할 것이며 이는 우리나라의 동북아 오일허브 정책에 크게 기여하게 될 것이다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권2호
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• pp.195-200
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• 2015

It is envisaged that the effect of increasingly stricter air emissions legislation implemented through IMO Annex VI and other local air quality controls, together with favorable financial conditions for the use of natural gas instead of liquid fuel oil as a bunker fuel, will see an increasing number of DF engine and single gas fuel engine applications to LNG carriers and other vessel types. As part of provision for the current international movements in the shipping industry to reduce GHG emission in air, new design concepts using natural gas as an alternative fuel source for propulsion of large commercial vessels, have been developed by shipyards and research institutes. In this study, an explosion analysis for a gas supply machinery room of LNG-fuelled container ship is presented. The gas fuel concept is employed for the high pressure ME-GI where a leakage in the natural gas double supply pipe to the engines is the subject of the present analysis. The consequences of a leak are simulated with computational fluid dynamics (CFD) tools to predict typical leak scenarios, gas cloud sizes and possible explosion pressures. In addition, capacity of the structure which is subject to explosion loads has been assessed.

• 항공우주시스템공학회지
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• 제8권3호
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• pp.34-40
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• 2014

Since the global economic crisis in year 2008, the world civil helicopter market has been growing recently. According to the market outlook in the next decade, the demand of civil helicopter will be driven by the demand of Private & Corporate, Oil & Gas, Off-shore and EMS(Emergency Medical Service) usages. On the other side, the demand of military market will be driven by the modification and upgrading for life extension or performance enhancement than the new helicopter development for replacing old models. To summarize these situations, the demand of MRO(Maintenance, Repair & Overhaul) market has also been on the rise because of the demand due to above several usages in civil side and the life-extension in military side. Through the MRO market analysis for characteristics, developmental trends and a supply chain, this paper describes that the potential of MRO business is considerably large as a propulsive power of domestic helicopter industry. And also, it proposes the construction direction of MRO network because the domestic industry must make the developmental awareness and reliability a stepping-stone towards own helicopter.

• 한국태양광발전학회지
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• 제3권2호
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• pp.48-54
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• 2017

Nowadays Viet Nam's energy supply which is mainly produced by fossil fuels energy such as coal, gas, and oil. However, the operation of fossil fuel power plants is one of the major causes of environmental pollution and climate change as well. It has a serious impact on the survival of human beings in general. As can be seen, the manufacturing industry is strongly invested, the demand for energy is also increasing. As traditional fossil fuels are being depleted and to minimize environmental pollution, renewable energy is the solution widely used by many countries in the world. Therefore, renewable energy has a significant role in maintaining the sustainability of world economy. Renewable energy sources such as solar energy, wind energy, biomass energy, geothermal energy can supply clean and nature-sourced energy to replace fossil fuels. Encouraging development of renewables is a general trend in the world today, which is also a common goal of COP21 commitment on global GHG reduction. The objective of this study is to assess the opportunities and challenges for renewable energy development in Vietnam, particularly for solar power. This study also discusses policies to promote the development of solar energy in Vietnam. While solar power provides ecological, economic and social benefits, it is exploited very modestly in Vietnam, where there are many barriers to slow down the development of renewable energy.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.67-72
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• 2006

Blower as an air supply system is one of the most important BOP (Balance of Plant) system fur FCV(Fuel Cell Vehicle). For generating and blowing compressed air, the motor of air blower consumes maximum 25% of net power and fuel cell demands a clean air. Considering the efficiency of whole FCV, low friction lubrication of high speed rotor is needed. For the purpose of reducing electrical power and supplying clean air to Fuel cell, oil-free air foil bearings are applied at the each side of brushless motor (BLDC) as journal bearings which diameter is 50mm. The normal power of driving motor has 1.7kW with the 30,000rpm operating range and the flow rate of air has maximum 160 SCFM. The impeller of blower was adopted a mixed type of centrifugal and axial which has several advantages for variable operating condition. The performance of turbo-blower and parameters of air foil bearings was investigated analytically and experimentally. From this study, the performance of the blower was confirmed to be suitable far 80kw PEM FC.