• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.37-45
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• 2012

This study investigates the pressure leakage characteristics of a desiccant rotor with a brush-type air seal. Through a pressure leakage experiment, a correlation equation for the leakage air flow rate is obtained as a function of the air seal area and pressure difference. Using this equation, an air leakage model for the desiccant rotor is developed. By comparing simulation results with the experimental results for the desiccant rotor, the accuracy of the air leakage model is demonstrated. A performance test of a desiccant rotor with various air flow rates is carried out. Using the air leakage model, the effective mass flow rate and air leakage rate are found. In addition, the characteristics of the air leakage are analyzed for a desiccant cooling system using the developed air leakage model.

• Journal of the Korea Convergence Society
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• v.11 no.12
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• pp.131-135
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• 2020

In this study, the models with three, five and ten wings of the propeller which made a light aircraft fly were performed by air flow analyses. As for the flow model A with the shape with five wings, Model A can be seen to be the most ideal flow of air. The flow of air through the number of wings, which is not too many or too few, shows the most smooth flowing form. The smaller the number of propeller blades, the smaller the flow of air. Model A is applied under pressure of up to 0.5631 MPa at the front of air flow. Also, models B and C are applied under pressures of 0.5758 MPa and 0.5589 MPa, respectively. Comparing the pressure contours for each model of flux, model B can be shown to have the highest pressure distribution. The result of this study can be used to investigate the air flow without actual testing. It also seems to be helpful in the aesthetic convergent design of light aircraft propeller.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.2
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• pp.48-59
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• 1992

In this paper, the effects of a skirt deformation on the responses of an Air Cushion Vehicle in waves are investigated. The air in the bag and in the plenum chamber is assumed to be compressible and to have a uniform instantaneous pressure distribution in each volume. The free surface deformation is determined in the framework of linear potential theory by replacing the cushion pressure with the pressure patch moving uniformly with an oscillating strength. And the bag-finger skirt is assumed to be deformed due to the pressure disturbance while its surface area remained constant. The restoring force and moment due to the deformation of bag-finger skirt from the equilibrium shape is included in the equations of hearse and pitch motions. The numerical results of motion responses due to various ratios of the bag and cushion pressure or bag-to-finger depth ratios are shown.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.98-103
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• 1996

석탄가스화복합발전소내 공기분리장치와 연계된 가스터빈 공기압축기의 성능병화를 예측할 수 있는 해석방법을 제안하였다. 공기분리장치와 연계된 가스터빈용 공기압축기의 성능변화는 유선곡률방법과 압력손실모델을 결합한 해석방법을 사용하였으며, 예측결과들을 실제 압축기성능 시험 결과와 비교하여 예측정확도를 검증하였다. 제안된 압축기성능 해석방법을 근간으로, 압축기와 공기분리장치의 연계조건인 열교환기의 핀치포인트 온도차, 추출공기량 및 추출 공기압력이 압축기 성능변화에 미치는 영향을 정량적으로 예측하였다. 공기추출량이 늘어나거나 핀치포인트 온도차가 커질수록, 압축기의 압축비 및 소요동력은 증가하나, 압축기 효율은 공기추출량의 증가에 따라 고압공기추출시에는 저하되고, 저압공기추출시에는 향상되었다. 더 나아가, 압축기의 일반화된 성능특성곡선의 제시를 통해, 압축기 효율을 극대화 할 수 있는 압축기/공기분리장치 간 연계조건의 최적화를 시도하였다.

• Journal of Biosystems Engineering
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• v.16 no.3
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• pp.298-311
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• 1991

빈 시스템에서 적정 팬을 선정하기 위해서, 빈에서 벼를 건조 혹은 통풍시킬 때 벼의 저항에 의해 발생되는 공기의 압력손실을 예측하는 모델을 개발하였다. 또한 벼의 건물 손실을 예측하기 위하여 벼의 호흡 모델을 개발하였다. 그리고 온도 및 습도 센서들을 이용한 자동계측 시스템을 사용하여 저장된 벼의 상태를 연속적으로 측정, 분석함으로써 벼의 통풍기준을 결정하고 이를 근거로 빈의 자동통풍 시스템을 개발하여 평가하였다. 공기의 정압 손실은 공기의 속도 및 벼의 함수율의 함수로서 나타내어졌으며, 일정 곡물 깊이에서 벼의 함수율이 낮을수록 그 정압손실은 증가하였다. 벼의 호흡에 의해 발생되는 이산화탄소의 양은 저장온도, 벼의 함수율, 저장 기간의 함수로서 나타낼 수 있었다. 벼의 안전 저장을 위해 곡물의 온도 및 함수율, 평형상대습도, 벼의 품질저하지수(deterioration index)에 대한 자동통풍 기준을 결정하였으며 이들을 이용해서 퍼스널 컴퓨터로 팬, 제습기 등의 통풍 장치들을 자동제어하는 자동통풍 시스템을 개발하였다. 이 시스템은 곡물의 상태를 예측, 제어함으로써 14% 이하의 함수율과 4이하의 품질저하지수, 그리고 어떤 균류도 생성시키지 않음으로써 벼를 안전하게 저장할 수 있었다.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.509-516
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• 2016

A blood flow simulator is one of the experimental devices used to better understand the cardiovascular system. Time-Domain analysis is not sufficient to understand the cardiovascular system because of the effects related to pulsating flows. Even when the mean pressure and mean flow rate of the blood flow simulators are satisfied, the dynamic properties can differ from the desired performance. In this paper, the Windkessel model, a well-known mathematical model of the cardiovascular system, was employed to obtain optimized pressure using initial values. The Windkessel parameters, including flow resistance, R, are expected to lead to a better understanding of the dynamic behavior of cardiovascular systems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.686-690
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• 2017

In this study, we numerically investigate the detonation characteristics (detonation velocity and pressure) of a hybrid ethylene-air and RDX mixture using two-phase model. Compared with detonation of pure ethylene-air mixture, the detonation of the hybrid ethylene-air and RDX mixture has higher pressure and stronger impulse because the hybrid mixture has additional chemical heat release of RDX particles. To validate the numerical results using two-phase model, we compare the experimental data which show changes of detonation pressure and velocity according to concentration of RDX particles.

• Journal of the Korea Convergence Society
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• v.10 no.9
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• pp.161-166
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• 2019

This study examines the flows near the different side mirrors by analyzing the flow due to air resistance at A, B and C models of automotive side mirrors. Model A is a square-shaped side-mirror. Model B is a triangular side-mirror and model C is an oval-shaped side-mirror. The air resistance of the side-mirror while driving is reduced and the automotive power can be reduced by changing the design of automotive side-mirror. As analysis result, as the pressure of air resistance against side mirror becomes larger, it can be seen that the air flow rate becomes great. Therefore, it can be estimated that the smaller the pressure of air resistance, the smaller the flow rate and the better the air flow. Therefore, it can be acknowledged that model B is the best model. As the design data of the automotive side mirror obtained on the basis of this study result are utilized, the esthetic sense can be shown while driving a car at real life.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.1-8
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• 2012

Acoustic-pressure response of diluted hydrogen-air diffusion flames is investigated numerically by adopting a fully unsteady analysis of flame structures in low and high pressure regimes. As acoustic frequency increases, finite-rate chemistry is enhanced through a nonlinear accumulation of heat release rate for any pressure regime, leading to a high amplification index. Same numerical results are analyzed with application of a pressure-sensitive time lag model, and thereby, interaction index and time lag are calculated for each pressure regime. The interaction index has the largest value in each pressure regime at an acoustic frequency near 1000 Hz. In a high-pressure regime, flames are more unstable than in a low-pressure regime. The interaction index shows a good agreement with the amplification index.

• Journal of the Korea Convergence Society
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• v.9 no.10
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• pp.265-270
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• 2018

In this study, the flow analysis due to the car body configuration of air breather was carried out. As the resistance force whose flow affects car body has been studied, it is published that the electricity can be decreased. When the inner pressure of air breather is evaluated, there is the study of efficiency in order to raise the flow rate of inner body. At a total of five models, it is shown that the air resistance and pressure happen differently and the air pressure of side flow is changed. This study result was analyzed by using the analysis program of ANSYS, a study model was modelled using the CATIA V5 modelling program. It was investigated that the air flow rate was distributed uniformly as the curved surface of air breather configuration increases. It is thought as the most effective design method to design the air breather by considering the effect on the air resistance and flow. Also, through the design of the vehicle's airbrid configuration, the design of the product can incorporate a aesthetic sense into the design.