• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.170-174
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• 2001

In this paper, CFD technique has been used at design stage to predict space air distribution in a cycle stadium with air circulation system. An air circulation flow of 0.67 rev./min was observed at computed results in the stadium space with and without air circulation system. Comparing the thermal comfort of the two models with or without air circulation system showed that the thermal environment in the former was superior in the latter. Energy savings could be achieved for the model with air circulation due to its lower air inflow temperature.

• 설비공학논문집
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• 제12권6호
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• pp.581-588
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• 2000

This paper describes the effect of vertical air circulation on the thermal environment in an airport passenger terminal with induced flow by jet fans. In comparing the level of thermal comfort at the breathing line of 1.5 m in height, the results from the two models with or without the vertical air circulation, show that the average PPD is 8% in the former and 23% in the latter, respectively. It is thought that vertical air circulation lends to improved thermal comfort for human in respect of ventilation in a large space.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1998년도 공동 심포지엄 및 추계학술발표회
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• pp.232-235
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• 1998

Air sparging system is a kind of in-situ bioremediation method in the contaminated ground water. When Air sparging, the both of water circulation and oxygen transfer happend in the same time. The hydraulic differential head is zero at the middle height of well, is negative below the height and is possitive above the height. Hydroraulic head gradient is proportioned to air superficial velocity in the well. But over 24m/min of the superficial velocity, the hydraulic head gradient increase little.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1927-1932
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• 2004

A 1/21.6 scaled non-heating experimental facility was prepared utilizing the results of a scaling analysis to simulate the APR1400 reactor and insulation system. The behaviors of the air bubble-induced two-phase natural circulation flow in the insulation gap were observed, and the liquid mass flow rates driven by natural circulation loop were measured by varying the injected air flow rate and distribution. As the injected air flow rates increased, the natural circulation flow rates also increased. Both the longitudinal and the latitudinal distributions of the injected air affected the natural circulation flow rates, especially, the longitudinal effect is more larger.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2626-2631
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• 2007

Air-water two phase natural circulation flow in the T-HERMES (Thermo-Hydraulic Evaluation of Reactor cooling Mechanism by External Self-induced flow)-1D experiment has been evaluated to verify and evaluate the experimental results by using the RELAP5/MOD3 computer code. The RELAP5 results have shown that an increase in the coolant inlet area leads to an increase in the water circulation mass flow rate. However, the water outlet area does not effective on the water circulation mass flow rate. As the coolant outlet moves to a lower position, the water circulation mass flow rate decreases. The water level is not effective on the water circulation mass flow rate. As the height increases in the air injection part, the void fraction increases. However, the void fraction in the upper part of the air injector maintains a constant value. An increase in the air injection mass flow rate leads to an increase in the local void fraction, but it is not effective on the local pressure.

• 한국환경과학회지
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• 제8권5호
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• pp.555-558
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• 1999

A sea/land breeze circulation system and a regional scale circulation system are formed at a region which has complex terrain around coastal area and affect to the dispersion and advection of air pollutants. Therefore, it is important that atmospheric circulation model should be well designed for the simulation of regional dispersion of air pollutants. For this, Local Circulation Model, LCM which has an ability of high resolution is used. To verify the propriety of a LCM, we compared the simulation result of LCM with an exact solution of a linear theory over a simple topography. Since they presented almost the same value and pattern of a vertical velocity at the level of 1 km, we had a reliance of a LCM. For the prediction of dispersion and advection of air pollutants, the wind filed should be calculated with high accuracy. A numerical simulation using LCM will provide more accurate results over a complex terrain around coastal area.

• 융합신호처리학회논문지
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• 제11권4호
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• pp.298-302
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• 2010

체외 순환 보조 장치는 호흡부전 및 심부전 등에 사용하는 장치이며 세계적으로 많은 연구 개발과 임상에의 사용이 계속되고 있다. 이 장치들을 사용할 때 주의해야할 사항중 하나는 공기 색전증이다. 공기 색전증은 정맥혈내로 공기가 들어갈 수 있는 여러 가지 수술 과정 및 진단 과정의 합병증으로 일어날 수 있으며, 수술부위가 심장보다 위치, 수술 과정 중 체강, 체외 순환 보조 장치를 사용할 때 공기의 유입이 생길 수 있다. 이러한 문제를 해결하기위해 비유전율 상수의 변화를 이용한 공기방울 감지 장치를 개발했다. 모의순환 장치에서 실험해본 결과 튜브 안의 공기 양에 따라 신호의 차를 분명하게 보여주어 공기방울을 감지할 수 있었다.

• Journal of Biosystems Engineering
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• 제37권2호
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• pp.75-81
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• 2012

Oyster mushroom farm which could not meet optimum temperature range yields non-uniform sized, low quality products. Thus, this study, utilizing STAR CCM+, one of the computational fluid dynamics (CFD) programs, analyzed the impact of air circulation and temperature distribution. Methods: After we visited numerous mushroom farms, we measured the temperature at the discharge ports of heaters, fan capacity, and the locations of the air circulators in the farms. According to the data, most mushroom growers installed the heaters near the entrance and discharge ports of the heaters at the third growing bed on the same height as the heaters in the entrance. The temperature at the discharge port of heater was $1,26^{\circ}C$, and the fan capacity was 4,500 $m^3$/hr. The air circulator was placed in the center of the mushroom farm 50cm above the ground, and its capacity of inlet port was 1,100 $m^3$/hr and discharge port 1,600 $m^3$/hr. The mushroom farm was insulated. Results: According to the analysis of the temperature distribution in the vertical plane of the entrance side, no air circulation causes the high temperature zone of 296~299K at the discharge port of the heater to take up 34% of area while the operation of air circulators causes it to occupy only 9%. This means that not using air circulators leads to a concentration of high temperature at the discharge port near the entrance. In addition, with the results of the analysis of the temperature distribution in the vertical planes of the center, no air circulation causes the temperature zone of 295~298K at the discharge port of the heater to take up 48% of area while the operation of air circulators causes it to occupy 80%. This shows that the high outlet port temperature disseminated to the center. Conclusions: After ninety minute operation of both heater and air circulator, the interior temperature became stabilized in the mushroom farm. Air circulation made the high temperature at the discharge port disseminate to the center and exit in the farm and equalize the temperature distribution.

• 한국해양공학회지
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• 제20권5호
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• pp.23-29
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• 2006

A quasi depth-varying mathematical model for wind-generated circulation in coastal areas, expressed in terms of the depth-averaged horizontal velocity components and free surface elevation was validated and used to understand the diurnal circulation process. The wind velocity is considered as a dominant factor for driving the current. In this paper, three-dimensional numerical experiments that included the land topography were used to investigate the mesoscale air flaw over the coastal regions. The surface temperature of the inland area was determined through a surface heat budget consideration with the inclusion of a layer of vegetation.A series of numerical experiments were then carried out to investigate the diurnal response of the air flaw and wind-generated circulation to various types of surface inhomogeneities.

• 농업과학연구
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• 제41권4호
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• pp.461-472
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• 2014

This study was conducted to build the CFD simulation model which can quantify the distribution of the meteorological factors in air-heated greenhouse for chrysanthemum according to the location and capacity of air-circulation fan. The CFD model was also verified by experiment. It was judged that SST model was the most appropriate turbulence model which can properly describe the airflow by the air-circulation fan. According to the simulation results, the differences between the measured and predicted temperatures from 18 points at each height in the greenhouse were $0.2{\sim}0.4^{\circ}C$ in average. This showed a good agreement between the predicted data and the measured ones. The developed CFD model can be a useful tool to evaluate and design the air-circulation systems in the greenhouse with various configurations.