• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.167-173
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• 2011

This paper considers the problem of revising train departure time to reduce electric power consumption of mass rapid transit (MRT) railways. The motion of a train running between stations is divided into three phases: traction, coasting, and deceleration phases. The traction phase requires high electric power to operate MRT railways. In the coasting phase, the train moves stably by consuming little or no power. The deceleration phase is a braking mode and produces some electric power called regenerated brake power owing to inertia force for the train generated In the traction and coasting phases. The regenerative energy can be used by other accelerating trains within a specific range from the train and thereby the power consumptions of train can be reduced. We developed a mixed integer programming model to solve the problem. To validate the suggested model, a computational experiment was conducted using real data from Korea Metropolitan Subway.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.276-280
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• 2021

The oxygen transfer rate at the liquid surface of the reciprocally shaking vessel was studied. The required power of the reciprocally shaking vessel was not proportional to the shaking frequency, unlike the rotational shaking vessel, and the liquid level suddenly fluctuated greatly at a certain frequency as the flow pattern in the vessel was a left and right wave flow different from that of the rotational shaking that has a rotational flow. The effect of the shaking frequency on the required power in the reciprocally shaking vessel was very complex, such as less power required than the rotational shaking vessel when the shaking frequency is more than 3 s-1, but the required power for the range of the generated rotational flow in the reciprocally shaking vessel could be correlated with the equation that was reported for the rotational shaking vessel. The kLa (mass transfer capacity coefficient) in the reciprocally shaking vessel also increased in a complex pattern because the required power for shaking was not consumed in a simple pattern, unlike kLa in the rotational shaking vessel, which increases linearly with increasing frequency. The kLa of the reciprocally shaking vessel was larger than the kLa of the rotational shaking vessel, and as the kLa value increased, the difference between them increased sharply. As a result, the oxygen transfer rate in the reciprocal motion was greater than that of the rotational motion, and could be correlated with the required power per unit volume.

• Journal of Power System Engineering
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• v.13 no.6
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• pp.29-34
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• 2009

Recently, we have a lot interest in a sudden rise of oil prices and a change weather for the earth warmming, so, development of new alternative fuels need in order to spare fossil fuel and reduce exhaust emissions for air pollution prevention. Biodiesel, which can be generated from natural renewable sources such as new or used vegetable oils or animal fats, may be used as fuel in diesel engine of compression ignition engine. In this paper, the combustion characteristics between neat diesel oil and biodiesel blends(10 vol.% biodiesel and 20 vol.% biodiesel) were tested using four stroke, direct injection diesel engine, especially this biodiesel was produced from soybean oil at our laboratory. This analysis showed that cylinder pressures, the rate of pressure rises and the rate of heat releases were decreased as the blending ratios of biodiesel to diesel oil increased because of lower heating value of biodiesel in spite of increased oxygen content in biodiesel.

• 월간 기계설비
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• no.11 s.220
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• pp.29-37
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• 2008

최근들어 국제 유가가 급등하고 지구 온난화 등 환경문제가 부각되면서 기존의 에너지를 대체하는 대안으로 신재생 에너지가 전 세계적으로 뜨거운 이슈로 떠오르고 있다. 더구나 온실가스 감축 등 본격적인 환경경제 시대가 도래하면서 환경친화적이고 고갈 염려가 없는 신재생에너지가 효과적인 대안으로 주목받고 있다. 또한 고유가 및 기술개발 가속화도 신재성에너지 시장 확대를 부채질하고 있어 신재생에너지에 대한 관심이 신성장동력으로 집중되고 있다. 이처럼 환경문제 해결에 대한 관심은 '선택'이 아닌 '필수'가 되었다. 우리나라도 국가 차원에서 이산화탄소 배출을 줄이기 위해 '저탄소 녹색성장' 정책을 마련하면서 신재생에너지 확대 보급을 위한 제도 및 대책이 새롭게 마련되고 있다. 건설산업은 대표적인 에너지 다소비업종에 속하기 때문에 이산화탄소 저감을 위해 에너지 저소비형 건축물 연구에 많은 투자를 하고 있으며, 신재생에너지를 이용한 생태토시 조성 등에 노력을 기울이고 있다. 특히 에너지를 다루는 기계설비는 이러한 신재생에너지와 밀접한 관련이 있기에 더욱 관심을 기울이고 있다. 태앙광을 비롯하며 지열, 풍력, 바이오 등 신재생에너지 개발은 물론 빗물이용 시스템 쓰레기 이송 설비와 같은 첨단과 환경이 조화를 이루는 아파트의 보급도 차츰 늘어나고 있는 추세다. '누구의 영역도 아닌' 곳이자 '누구의 영역도 될 수 있는' 신재생에너지가 설비건설업계에 확대, 보급되기 위해서는 설비건설업계의 관심이 집중되어야하며, 기술개발을 활발히 하여 선점경쟁에서 유리 한 고지를 접할 수 있을 것이다. 그렇다면 국내 신재생에너지의 개발 수준은 어디까지 왔을까? 이번 호는 그 현황을 집중 조명해 보고, 다음 호에는 풍력, 바이오에너지, 지열, 연료전자 수소 등을 하나씩 분석해 본다.

• The Magazine for Energy Service Companies
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• s.84
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• pp.8-11
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• 2013

지난 5월 28일 국무회의에서 박근혜 대통령은 "과학기술을 통한 에너지 효율성을 제고하거나 낭비를 막는 방법도 있고 스마트 그리드 같은 IT기술을 이용해서 실시간으로 자신이 얼마를 소모하는지 알려줌으로써 스스로 아껴 쓸 수 있는 방법이 있는데, 그런 방안도 적극 연구해 달라"고 당부했다. 실제로 우리 산업은 현재 ICT기술과 전력시장을 창조적으로 융합하여 새로운 시장을 형성하고, 이를 통해 신(新)성장동력, 신(新)서비스업을 육성해야 하는 시점에 직면해 있다. 전력공급에 소요되는 사회적 비용이 급증하여 빠른 속도로 증가하는 수요를 충족시키는데 많은 어려움이 있는 것도 사실이다. 늘어나는 수요에 따라 공급을 확대하는 공급중심 정책에서 합리적으로 수요를 줄인 후 공급을 확대하는 수요관리 중심의 정책으로 전환이 필요한 때이다. * 연평균 전력소비증가율('00~'10년, %) : 한국 5.3('10년 10.1), 일본 0.2, 미국 0.7, OECD 평균 1.0 최근 다각도로 전력 사용을 줄이기 위한 이벤트가 실시되고 있는데 실내온도 제한 등 일시적 절약에서 벗어나, 세계적 수준의 우리 ICT기술을 활용하여 근본적이고 시스템적인 수요관리 추진이 필요하다. 한편 전력수급 위기를 새로운 시장창출의 기회로 만드는 발상의 전환을 통해 창조경제시대의 신성장동력과 일자리를 창출하게 되는 기회가 될 수 있다. 이는 전통적인 에너지산업에 2차전지산업, 소프트웨어 산업을 융합하여 ESS, EMS, LED 등 ICT기반 에너지 신산업 시장 진출을 의미한다. 이번호에서는 ESS(Energy Storage System)라고 불리는 에너지저장장치에 대해 살펴보고자 한다.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.5-10
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• 2005

The effect of ultrasonic energy for diesel fuel and blend oil has been revealed in this paper. The experimental setup consisted of a high speed diesel engine with 4 cylinder, dynamometer and ultrasonic fuel feeding system. Ultrasonic energy was added to diesel fuel and blend oil, which is a blend of diesel fuel and rape-seed oil. As engine speed was changed, engine torque and power, brake specific fuel consumption and thermal efficiency were measured in detail. As the results, by adding ultrasonic energy to diesel fuel and blend oil, the engine performance was improved in range of the experiment. The effect of improvement on brake specific fuel consumption and thermal efficiency for blend oil is higher than that for diesel fuel. When ultrasonic energy was added to diesel fuel or blend oil, a rise in engine torque for diesel fuel was higher than that for blend oil, but the effect of ultrasonic energy was small. From these results, it may be desirable to add ultrasonic energy to blend oil for the use of blend oil to diesel engine.

• Journal of Power System Engineering
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• v.19 no.6
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• pp.39-46
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• 2015

With rising fuel costs and the depletion of fossil fuels, electric vehicles of high efficiency has been increasing interest. although high-performance battery continually is developing, Electric vehicles is not satisfied with the characteristics of the environment. In this study, By using the current fuel economy testing methods(5-cycle test), until the fully discharged battery electric vehicles is evaluated for a variety of environmental and operating conditions. As a result, Electric vehicles showed a low energy consumption efficiency in low temperature and rapid acceleration, deceleration in the operating environment compared with normal temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.3
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• pp.307-314
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• 2015

The purpose of this study is know the fuel economy of difference tractive resistance calculation methods on light duty low-floor bus. Two tractive resistance calculation methods(coastdown test and JFCM conversion formula) are tested to understand the difference of fuel economy. JFCM was developed for fuel economy regulations of heavy duty vehicle. That show a big difference as a result of the calculation using coastdown test and JFCM conversion formula. The difference of the tractive resistance affects the fuel economy.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.70-76
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• 2014

Surely fuel economy(F.E.) label is needed to meet consumer's right to know. Korea has developed and adopted F.E. correction equation similar to the feeling, because consumer complain about F.E. label higher than they feel. Recently, through continuous research and development high-efficiency & performance green car like HEV, PHEV and EV are being sold. In this situation, it is needed to know whether the current equation can reflect a part of their improved technic or not. In this paper, to review current equation through test using hybrid vehicles on 5-cycle SOC, correction equation and F.E were discussed. The result show HEV didn't meet the SOC error standard on US06. Also, HEV has bigger F.E. difference between FTP-75 and 5-cycle than conventional vehicles. However, the correction equation that include HEV almost same with current one.

• Journal of Power System Engineering
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• v.21 no.4
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• pp.84-93
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• 2017

This study was carried out to improve the electric power consumption of HVAC in the blow mold machine(BMM) and work environment. The experiment was conducted with the simulated HVAC system of 1/15 of the actual BMM. The temperature of main facility and two preheaters was fixed at 200 and $60^{\circ}C$ respectively in all test conditions. The measured points of temperature were chosen as critical locations considering the work environment. The tendency of temperature distributions decreases as the duct was closed to the main facility. The reduction rate of power consumption of HVAC increases up to 32.3% when both duct and cooling systems are operated. Also the efficiency of HVAC is improved about 9% through the modified design of duct system. It notes that the electric power consumption of HVAC can be reduced by the optimum design and operating condition of duct and cooling system.