• Journal of Advanced Marine Engineering and Technology
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• 제24권4호
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• pp.421-426
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• 2000

A study on the combustion and exhaust emissions characteristics of diesel engine with various suction air humidity is performed experimentally. In this paper, suction air humidity is changed from RH 50% to RH 90%, the experiments are performed at engine speed 1800rpm, and main measured parameters are cylinder pressure, fuel consumption rate, CO, HC, NOx and Soot emissions etc. Increase of suction air humidity from RH 50% to RH 90% does not effect specific fuel consumption, decreases maximum pressure in cylinder, ratio of maximum pressure rise and net heat release, and delays ignition timing. Also, that increases CO and HC emissions, decreases NOx emissions, but does not constant in changing tendency on emission.

• 해양환경안전학회지
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• 제21권3호
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• pp.303-308
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• 2015

Compressed air has many uses on board ship, ranging from diesel engine starting to the cleaning of machinery during maintenance. In an effort to enhance the performance of the marine compressed air system, this work studied a way to reduce condensation from the air compressor via experiments. Especially more condensation is produced when the temperature at compressor outlets and the humidity of the air are higher. so in the research, drain production change has been observed by additionally installing the cooling fan on the suction portion of the air to air compressor and this is the method for reducing the compressed air drain that has passed through the compressor. For the result, it was verified that when the cooling fan was used, less drain was made where per hour it was 500.9ml of drain and the measured result after installing the cooling fan was that less drain was made. Other additional and various researches are needed including experiments like silica gel passing through the suction portion afterwards.

• Journal of Advanced Marine Engineering and Technology
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• 제38권6호
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• pp.609-614
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• 2014

화산지형인 제주도의 지열에너지를 사용하기 위하여 지하공기를 측정하였을 때 지중 온도는 $15{\sim}18^{\circ}C$이며, 상대습도는 70~80%로 타 지역에 비하여 매우 높은 경향을 나타내고 있다. 본 연구는 제습기능 및 난방기능을 구비한 다단 제습 가열 열펌프 시스템의 개발에 관한 연구로써, 개발된 열펌프의 성능실험을 수행한 결과 흡입공기의 상태가 최저 $15^{\circ}C$, 60%인 경우 총제습량이 1.797(kg/h)로 나타났으며, 최고 $20^{\circ}C$, 80%인 경우 총제습량이 45% 증가한 3.269(kg/h)로 증가하여 충분한 제습이 이루어짐을 알 수 있다. 또한, 난방능력은 흡입온도 $17^{\circ}C$ 상대습도 70% 일 때 1.91로 가장 높은 효율을 얻을 수 있다.

• Geomechanics and Engineering
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• 제37권2호
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• pp.109-122
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• 2024

Standard triaxial cells are commonly used to measure the mechanical behavior of saturated soils. However, this type of standard system is difficult to use for unsaturated soil specimens since it cannot measure the changes in the pore-air volume and pressure. This paper proposes to extend the measurement possibilities of the standard triaxial testing device in a simple way and to adapt it to partially saturated soils. The system is supplied by two hygrometers installed at each end of the cylindrical unsaturated specimen to measure local relative humidity, which allows the derivation of suction. The volumetric strain of the specimen is calculated by analyzing digital photos captured from the outside of the transparent cell wall. Specimens made of kaolin clay, having different hydraulic properties, were tested to verify the reliability of the measurements, and thus, the relevance of the proposed techniques to study the mechanical behavior of unsaturated soils.

• 대한기계학회논문집
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• 제13권3호
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• pp.547-553
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• 1989

본 연구에서는 작동유체로서 수증기와 거동이 유사한 습공기를 대기 흡입식 풍동을 사용하여 원호 노즐로서 팽창시키는 경우에 대하여 응축충격파가 발생하는 흐름이 측정부내에 쐐기를 설치하여 발생시킨 경사충격파에 미치는 영향에 대해 실험적으로 조사하였다.

• 대한기계학회논문집
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• 제18권8호
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• pp.2177-2183
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• 1994

The rapid expansion or condensible gas such as moist air of steam gives rise to nonequilibrium condensation. As a result of irreversibility of condensation process in the supersonic cascade flow of low pressure steam turbine, the entropy of the flow is increased, and the efficiency of the turbine is decreased. In the present study, to investigate the flow of moist air in 2-dimensional cascade made as the configuration of the tip section of the last actual steam turbine moving blade, the static pressure at both sides of pressure and suction of blade are measured by static pressure taps and the distribution of Mach number on both surfaces of the blade are obtained by using the measured static pressure. Also, the flow field is visualized by a schlieren system. From the experimental results, the effects of the stagnation temperature and specific humidity on the flow properties in a 2-dimensional stationary cascade of a practical steam turbine blade are clearly identified.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1658-1663
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• 2015

실내의 습도제어를 위하여 공조기 내에는 가습소자가 설치된다. 지금까지 대부분의 가습소자는 유리섬유로 만들어진 외제품이 널리 사용되어 왔다. 본 연구에서는 이 외제품을 대체할 셀룰로오스와 PET 복합체로 만들어진 가습소자를 개발하고 유리섬유로 만들어진 Glasdek 소자의 성능과 비교하였다. 시험은 소자를 항온항습실 내에 설치된 흡입식 풍동입구에 설치하고 물질전달량과 압력손실을 측정하였다. 실험결과를 $j_m$과 f인자로 나타내었을 때, 개발품의 $j_m$값이 33%~39%크고, f인자는 개발품이 0%~51% 작게 나타났다. Glasdek에 비하여 개발품의 $j_m$값이 큰 이유는 흡수도가 월등히(50% 가량) 크기 때문이고 f인자가 작은 이유는 소자 표면이 확연히 매끄럽기 때문이다. 한편, 동일 소비동력 대비 물질전달을 나타내는 $j_m/f^{1/3}$ 의 경우, 개발품이 약 36~63% 크게 나타났다.