• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.1
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• pp.83-89
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• 2009

Generally, automobile cooling fan is used to lower the temperature of radiator. The cooling fans are manufactured by plastic injection molding process. The center of gravity of cooling fan is often deviated from the center due to the use of deteriorated materials. As the unbalanced of the cooing fan can generate noise, it is required to measure the degree of deviation of center of gravity in the cooling fan. In this work, automatic fan balancer which can effectively detect the magnitude and position of the unbalanced cooling fan is proposed and several experiments are carried out to verify the feasibility of the proposed algorithm.

• Tunnel and Underground Space
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• v.28 no.1
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• pp.38-58
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• 2018

The ventilation system plays a crucial role in underground mine safety. The main objective of the ventilation system is to supply sufficient air to dilute the contaminated air at working places and consequently provide tenable environment during the normal operation, while it also should be capable of controlling the fire propagation and facilitate rescue conditions in case of fire in mines. In this study, a smoke control fan was developed for the auxiliary ventilation as well as the fire smoke exhaust. It works as a free-standing auxiliary fan without tubing to dilute or exhaust the contaminated air from the working places. At the same time, it can be employed to extract the fire smoke. This paper aims to examine the smoke control efficiency of the fan when combined with the current ventilation system in mines. A series of the site experiments and numerical simulations were made to evaluate the fan performance in blind entry development sites. The tracer gas method with SF6 was applied to investigate the contaminant behavior at the study sites. The results of the site study at a large-opening limestone mine were compared with the CFD analysis results with respect to the airflow pattern and the gas concentration. This study shows that in blind development entry, the most polluted and risky place, the smoke fan can exhaust toxic gases or fire smoke effectively if it is properly combined with an additional common auxiliary fan. The venturi effect for smoke exhaust from the blind entry was also observed by the numerical analysis. The overall smoke control efficiency was found to be dependent on the fan location and operating method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.271-277
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• 2003

Recently as the environmental noise getting influential social problem, it is the fact that the demand on noise reduction increases with the advance of the standard of living. Therefore increasing the interest on the noise in common, it is eagerly demanded that the endeavour for reducing the noise of the rotating machinery, especially the machinery related a flowing including the household electric products, which is pointed out the primary noise source in environment. As proceeding study for fan noise, theory of fan noise property is arranged and this control method is shown. Blade passage noise of total noise spectrum. Thus in the aspect of noise reduction, noise source and identification of noise radiation characteristics of axial flow fan are demanded in detail. The sound source is analyzed by using sound pressure and sound intensity. In that time, synchronization of axial flow fan using optical sensor is executed, and to identify the location of exact noise source in the fan profile determination of recording time is proposed. In the rotating of tan, it is explained that the location of noise source exists in and by the directivity, the noise radiation pattern of axial flow fan is determined and the flow of sound is visualized in the figure of contour mapping.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.195-202
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• 2010

Cooling air-conditioning of APC (Agricultural Products processing Center) workplace is important to improve the working environment in the summer season. As existing cooling systems for air-conditioning of whole workplace are inefficient because of their high equipment operating costs, relatively inexpensive cooling system is required. The objectives of this study were to simulate the thermal flow fields in APC workplace having the positive and negative pressure type fan and pad systems and spot cooling system by using CFD software (FLUENT, 6.2) and estimate the cooling effectiveness of respective cooling systems. The results showed that the negative pressure type fan and pad system was inappropriate for the present APC workplace because of excessive outside air influx from open gateway and the positive pressure type fan and pad system created relatively low temperature field but non-uniform velocity field at worker positions. The spot cooling system could supply cool air to worker positions with relatively constant air velocity and temperature.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.1
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• pp.1-12
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• 2022

Wind tunnel test for a small scale electric ducted fan with a 104mm diameter was conducted to analyze the aerodynamic characteristics when it was used as a propulsion system of tilt-propeller UAV. Experimental conditions were derived from flight conditions of a sub-scaled OPPAV. Forces and moments of the ducted fan model were measured by a 6-axis balance and 3-dimensional wake vectors which could induce an aerodynamic influence in the vehicle were measured by 5-hole probes. Thrust and torque on hover and cruise conditions were measured and analyzed to drive out the operating conditions when it was applied in the sub-scaled OPPAV. On transition conditions, thrust keep its value with tilt angle variation below 40° and increase after that. But, sideforce increase constantly until 75°. The maximum axial velocity in the wake on hover and cruise conditions was around 60m/s and tangential velocity was around 12m/s. The position of the maximum axial velocity and vortex center move off the fan rotation center line as the tilt angle increases.

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.50-55
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• 2002

In this numerical study, characteristics of swirl generation by the fan and selection of the location of the fan was studied theoretically by the modified TEACH code. The governing equations for the system are solved by means of the k dimensional version of the SIMPLE method and STAGGERED grid. From the present results, the optimal position of the fm is 0.625(h/H).

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.06a
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• pp.42-46
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• 2000

In this numerical study, characteristics of swirl generation by the fan and selection of the location of the fan was studied theoretically by the PHOENICS soft ware. The governing equations for the system are solved by means of the three dimensional version of the SIMPLE algorithm and STAGGERED grid. From the present results, the optimal position of the fan is 0.625($\ell$/L). Here we can survey the big swirl near the fan.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.105-109
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• 2004

우리나라 지형의 특성은 약 70%가 산으로 이루어져 있다. 이러한 지형적 여건은 교통과 관련된 사회간접 자본의 증가로 이어지며, 최근에는 산업의 발전에 힘입어 교통량의 증가와 물류비용의 절감을 목적으로 철도 및 도로의 건설시 터널의 계획 및 시공이 증가되고 있는 추세이다. 이에 따라 터널의 환경개선과 화재시 제연을 목적으로 설치되는 제트팬(Jet Fan)의 용량이 차지하는 전기적 비중이 높아지고, 전압강하에 대한 손실율이 증가되고 있다. 따라서 제트팬의 설치시 배치방법과 터널의 길이에 따른 전기실 배치를 Case 별로 분류하여 전압강하를 계산하고 분석하여 가장 효율적이며 경제적인 방안을 연구하고 정리하여 향후 설계시 기초자료를 제공하고자 하였다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2016.11a
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• pp.275-277
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• 2016

본 논문에서는 Door Fan Test 수행 사례를 중심으로 사전 준비에 필요한 사항에 대해 분석하였다. 분석 결과 관통부 주위 개구부, 벽체 틈새 개구부 등 방화구역의 누설부위를 통해 약제가 누출되는 문제가 있었다. 원인으로는 전기배선 공사로 인해 내화충전된 부분을 제거하고 공사 후 다시 충전하지 않는 경우, 벽과 천장사이의 틈을 내화 실란트 등으로 마감을 하지 않은 경우가 대부분이었다. 이와 같이 누설부위가 많은 경우 테스트의 결과 불합격이 나오게 되며, 이러한 문제점을 개선하기 위해 사전현장조사를 통해 방호구역의 누설부위를 조사하고 보완조치를 진행한 후 테스트를 수행하는 절차가 필요하였다. 한편, 테스트 운영에 관한 사항으로는 해당 실(room)을 위한 충분한 유량 미확보, 장애물로 인한 와류형성, 차압측정구의 설치문제 등이 있었다. 이를 개선하기 위해서 공기를 유입하는 실은 외부로부터 충분한 공기유입이 있어야하며, 팬 앞의 장애물을 제거하거나 팬의 설치 위치를 조정하는 것이 필요하며, 공기의 유동이 가장 적은 곳에 측정구를 설치하는 등의 조치가 필요하다.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.45-55
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• 2004

In this study, a time marching free wake method was used for the aerodynamic analysis and the boundary element method was used for the aeroacoustic analysis of the Tail Fan, respectively. In addition, variations of blades position in duct were performed and the aeroacoustic analysis shows a marginal improvement in noise level.