• Solar Energy
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• v.12 no.1
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• pp.34-39
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• 1992

The present study has carried out thermal performance evaluation of air systems for space heating in Daejeon by the f-chart method. The various effects with the change in air flow rate, number of glazings, storage capacity of pebble bed, and coating materials of absorber plate are analyzed with regard to the effectiveness of air systems for space heating. A comparison is also made with liquid systems under the same operating conditions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.435-436
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• 2008

The manufacturing technology used for next generation high-speed air-breathing engines, such as ramjet engine, scramjet engine and so on, was classified and reviewed to check up if pre-occupied manufacturing technology in Hyundai Rotem and other Korean companies in the field of liquid rocket engines, gas turbines and afterburners can be applied for fabricating next generation air-breathing engines.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.235-240
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• 2010

Transpiration cooling is the most effective cooling technique for liquid rocket and air-breathing engines operating in aggressive environments with higher pressures and temperatures. Combustor liners and turbine vanes are cooled by the coolant(air or fuel) passing through their porous walls and also the exit coolant acting as an insulating film. However, its practical implementation has been hampered by the limitations of available porous materials. The search for more practical methods of increasing the internal heat transfer within the walls has led to the development of multi-laminate porous structures, such as Lamilloy$^{(R)}$ and Transply$^{(R)}$. This paper reviews recent research activities of transpiration cooling for the propulsions of liquid rocket, gas turbine, and scramjet.

• Journal of the korean Society of Automotive Engineers
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• v.9 no.3
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• pp.16-22
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• 1987

직접분사식 디젤기관의 성능과 배기가스 문제에 여향을 주는 실린더 내에서의 연소형태는 크게 연료분사계와 흡입공기 유동계 두 가지에 의해 결정된다. 즉 분사율, 부사시기, 분무형태와 같은 분사계의 특성과 공기선회, 스퀴시(squish), 난류와 같은 공기 유동 특성에 의하여 연소형태가 결 정된다. 이러한 복잡한 연소형테를 기관 특성에 맞게 조정한다는 것은 대단히 어려운 문제인데 이것은 연료화 공기의 혼합이 연소실형상과 흡기계의 형상에 큰 영향을 받으며 연료가 액체 상 태로 연소실내로 들어와 분무과정을 통하여 증발이 되어야만 연소가 가능하기 때문이다. 특히 흡입공기 유동계에 있어서 현재의 직접 분사식 대젤기관의 흡입구 형상은 흡입공기의 운동에너 지에 모멘트를 가하여 연소실내에서 공기의 선희(swirl)를 발생시켜 줌으로써 연료와 공기의 혼 합기를 형성시키는 Helical type이 많이 이용되고 있다. 그러나 기관 성능과 배기가스 특히 NOx는 상반관계를 이루기 때문에 연소실내로 들어오는 흡입공기의 선희강도(swirl ratio)를 너무 강하게만 한다고 하여 좋은 결과를 얻을 수는 없다. 따라서 설계하고자 하는 각 기관에 있어서 요구되는 성능과 배기가스 문제를 만족하는 흡입공기의 선희강도가 얻어질 수 있도록 흡입구 형상을 설계한다는 것은 많은 연구와 경험이 요구되고 있다. 본 자료에서는 직접분사식 디젤기 관에 있어서 흡입공기의 최적 선희강도에 대한 설정방법과 흡입구 형상 설계를 위한 설계 이론 및 정상류 Rig test상에서의 흡입공기 선희강도의 평가방법을 소개하고자 한다.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.588-592
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• 2006

PV Thermal combined system produces the electricity and thermal energy which are needed for buildings. The system removes heat from PV module through air or liquid, so that its efficiency will be improved. The heat as the forms of hot air or hot water can be utilized for building use, like space heating and hot water. This paper describes the concept of PV Thermal combined system and its research and development trend at local and international levels. This materials can be used as a fundamental study source about PV Thermal combined system to apply fur building space heating.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.1
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• pp.67-74
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• 2013

A jet in a crossflow (JICF) has been extensively studied because of its wide applications in technological systems, including fuel injection into a ram-combustor. However, in the case of insufficient mixing performance of the liquid jet into the crossflow, the flame in a ram-combustor is unstable. In this study, the nonuniform flame and combustion instabilities due to lack of mixing performance were experimentally investigated. By performing correlations to predict the penetration height and break-up point, the spray and mixing characteristics of JICF have been studied. In particular, the improved correlations of penetration height are proposed in two distinctive domains depending on the X/d location of the crossflow.

• Korean Journal of Food Science and Technology
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• v.15 no.4
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• pp.348-352
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• 1983

The atomization of barley tea concentrate with paint spray gun of two fluid nozzle was investigated. The physical properties of barley tea concentrate were correlated to the operating parameters; soluble solid concentration, viscosity, specific gravity and surface tension. The air to liquid feed ratios at various barley tea concentration were correlated to the air pressures applied. The diameters of sprays at various air pressures (from 164 mmHg to 564 mmHg) and soluble solid concentrations (from 3.1% to 25.2%) were also investigated.

• Fire Science and Engineering
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• v.20 no.3 s.63
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• pp.29-34
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• 2006

The flash and fire point are the most important combustible properties used to determine the potential for the fire and explosion hazards of flammable material. The flash point is defined as the lowest temperature at which a flammable liquid gives off sufficient vapor to form an ignitable mixture with air near its surface or within a vessel. The fire point is the temperature of the flammable liquid at which there will be flaming combustion, sustained 5 seconds in response to the pilot flame. In this study, the flash points and fire points were measured to present raw data of the flammable risk assessment for acids, using Pensky-Martens Closed Cup(C.C.) apparatus (ASTM-D93) and Tag Open-cup (O.C.) apparatus(ASTM D 1310-86). The measured fire points were compared with the estimated values based on 1.11 times stoichiometric concentration. The values calculated by the proposed equation were in good agreement with measured values.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.837-845
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• 2013

An airlift pump can be used to pump liquids and sediments within itself, which cannot easily be pumped up by a conventional method, by using the airlift effect. This characteristic of the airlift pump can be exploited in a DCFC (Direct Carbon Fuel Cell) so that molten fuel with high temperature may be carried or transported. The basic characteristics of airlift are investigated. A simple system is constructed, where the reservoir is filled with water, a tube is inserted, and air is supplied from the bottom of the tube. Then, water is lifted and its flow rate is measured. Bubble patterns in the tube are observed in a range of air flow rates with the parameters of the tube diameter and submergence ratio, leading to four distinct regimes. The pumping performance is predicted, and the correlation between the supplied gas flow rate and the induced flow rate of water is found.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.513-518
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• 1996

저농도 방사성 액체폐기물의 최종 처리를 목적으로 본 연구에서는 면 35%와 Polyester 65%가 함유된 합성섬유를 증발매체로 하여 자연상태의 공기를 강제 송풍시키는 자연증발처리시설에서 증발에 영향을 미치는 주요 변수에 따라 증발 단위 면적당 Cs-137, Co-60을 함유한 방사성 폐액의 증발량측정 및 제염계수를 조사하였다. 증발효과는 유입공기의 습도가 낮고, 공기의 유속과 공급액의 유량이 증가하고 유입공기 및 폐액의 온도가 높아질수록 증발량이 증가하였다. 실험결과 유입된 공기는 1$0^{\circ}C$ 이상, 습도는 80% 이하, 공급폐액의 유량이 3.4 $\ell$/hr $m^2$ 이상, 공기유속은 1.14~l.47 m/sec 범위가 조업조건이며 이때 제염계수는 5.1 $\times$ $10^3$, 배출공기의 방사능 농도는 4.7$\times$$10^{-13}$ $\mu$Ci/$m\ell$ air로 측정되었다. 공급유량이 4.6$\ell$/hr.$m^2$와 공기유속이 1.47 m,/sec일때 최대 증발조건으로 나타났으며, 이때 증발량은 총 증발면적 11,250$m^2$ 에서 1.2 ㎥/hr로 측정되었으며 대기의 온.습도 및 풍속에 따른 실험을 통하여 달톤형 증발식의 Wind Factor ［Eh ＝ (0.0168 ＋ 0.0141V)$\Delta$H］를 도출하였다.