• 한국항해항만학회지
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• 제31권1호
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• pp.29-33
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• 2007

파력발전장치 중 진동수주(Oscillating Water Column)형은 3단계 에너지 변환과정을 거치게 된다. 그 중 파랑에너지를 공기에너지로 변환하는 장치인 공기실의 형상을 바꿔가며 그에 따른 성능을 상용 CFD 코드인 FLUENT를 이용한 수치 해석 기법으로 연구하여 보았다. 통상 OWC형 파력발전장치는 공기실과, 터빈이 설치되는 덕트 간에 효율적인 이유로 급축소 형태를 취하고 있는데 이 때 공기실과 터빈 연결부의 형상이 파력발전 장치 전체 성능에 중요한 영향을 미치므로 공기실내의 압력을 최소화하고 터빈 유입유속의 가속화가 용이한 가장 적합한 형상을 정상 및 비정상 해석을 통하여 찾고자 하였다.

• 한국정밀공학회지
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• 제24권6호
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• pp.86-95
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• 2007

This paper presents the optimal design of an exhaust system of a vacuum-compatible air bearing using a genetic algorithm. To use the air bearings in vacuum conditions, the differential exhaust method is adopted to minimize the air leakage, which prevents air from leaking into a vacuum chamber by recovering air through several successive seal stages in advance. Therefore, the design of the differential exhaust system is very important because several design parameters such as the number of seals, diameter and length of an exhaust tube, pumping speed and ultimate pressure of a vacuum pump, seal length and gap(bearing clearance) influence on the air leakage, that is, chamber's degree of vacuum. In this paper, we used a genetic algorithm to optimize the design parameters of the exhaust system of a vacuum-compatible air bearing under the several constraint conditions. The results indicate that chamber's degree of vacuum after optimization improved dramatically compared to the initial design, and that the distribution of the spatial design parameters, such as exhaust tube diameter and seal length, was well achieved, and that technical limit of the pumping speed was well determined.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.621-625
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• 2007

Oscillating wave amplitude in a bottom-mounted owe chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. In numerical scheme, the potential problem inside the chamber is solved by use of the Green integral equation associated with the Rankine Green function, while outer problem with the Kelvin Green function taking account of fluctuating air pressure in the chamber. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly.

• 태양에너지
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• 제7권1호
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• pp.14-22
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• 1987

This paper presents an experimental study of a solar drying system designed and installed by KIER. Experiments have been performed using the KIER system for the drying of marine products, such as squid. Presented in detail are the experimental observations of collector air temperature, solar intensity, absorber plate temperature, drying chamber temperature, humidity and other measures of drying chamber performance with variation of air mass flow rate. As a result, average temperature attained in the drying chamber during autumn weather has been adequated for drying of squids.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.611-612
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• 2010

• Journal of Mechanical Science and Technology
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• 제19권9호
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• pp.1811-1820
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• 2005

Thermo-acoustic instability of methane/ air flames in an industrial gas-turbine combustor is numerically investigated adopting CFD analysis. The combustor has 37 EV burners through which methane and air are mixed and then injected into the chamber. First, steady fuel! air mixing and flow characteristics established by the burner are investigated by numerical analysis with single burner. And then, based on information on the flow data, the burners are modeled numerically via equivalent swirlers, which facilitates the numerical analysis with the whole combustion system including the chamber and numerous burners. Finally, reactive flow fields within the chamber are investigated numerically by unsteady analysis and thereby, spontaneous instability is simulated. Based on the numerical results, scaling analysis is conducted to find out the instability mechanism in the combustor and the passive control method to suppress the instability is proposed and verified numerically.

• 오토저널
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• 제14권4호
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• pp.31-38
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• 1992

The objective of this study is to determine the ignition feasibility of a single shot, air-assisted gasoline fuel injector operated in a constant volume combustion chamber under atmospheric condition. A number of parameters has been selected for this experiments, such as dwelling time, spark gap position(r,z), spark electrode geometry, supplied air and fuel masses and spray cone deflector angle. On-site visual inspection of the instantaneous flame glow was chosen as one way to judge the successful ignition. In addition, chamber pressure and occasional photography were mobilized as for data recording. It was clearly observed that there was an entrainment air-fuel mixture toward spray axis from the spray formation and its development later on. The optimum ignition conditions were found for those parameters given above.

• 설비공학논문집
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• 제18권7호
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• pp.563-570
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• 2006

We investigated the emission characteristics of gaseous organic contaminants from building materials and newly constructed apartments. The emission test for building materials was done with small chamber method, and field measurements in newly constructed apartment were carried out by Korea Standard Test Method for Indoor Air Quality. First, the emission test by small chamber showed that the TVOC emission from building materials was much higher than formaldehyde. On the other hand, as expected, considerably high concentration of both TVOC and HCHO was detected in the new apartment.

• 한국자동차공학회논문집
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• 제11권4호
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• pp.29-36
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• 2003

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at spark plug and the combustion characteristics of inhomogeneous charge methane-air mixture under several parameters. The flow characteristics such as mean velocity and turbulence intensity was analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer was used to investigate the effect of initial charge pressure, excess air ratio and ignition times on combustion pressure and combustion duration. Mean velocity and turbulence intensity had the maximum value at 200 or 300ms and then decreased to beneath 0.05m/s gradually at 3 seconds. Second mixture is accompanied by an increase in the combustion rate, and that the higher the mass which is added in the second stage injection, the faster the burn rate.

• Geomechanics and Engineering
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• 제21권3호
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• pp.237-245
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• 2020

The process of evaporation from free water surface was simulated in a large scale environmental chamber under various controlled atmospheric conditions and also was modelled by a new mass transfer model. Six evaporation tests were conducted with increasing wind speed and air temperature in the environmental chamber, and hence the effect of atmosphere parameters on the evaporation process and the corresponding response of water were investigated. Furthermore, based on the experiment results, seven general types of mass transfer models were evaluated firstly, and then a new model consisted of wind speed function and air relative humidity function was proposed and validated. The results show that the free water evaporation is mainly affected by the atmospheric parameters and the evaporation rate increases with the increasing air temperature and wind speed. Both the air and soil temperatures are affected by the energy transformation during water evaporation. The new model can satisfactorily describe the evaporation process from free water surface under different atmospheric conditions.