• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.792-797
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• 2003

A helical vane is applied to reduce the magnitude of the impulse wave discharged from the exit of a duct. A shock tube with an open end is used to investigate the effect of the helical vanes on the impulse wave magnitude. Four different types of helical vanes are installed into the low-pressure tube of shock tube. The magnitude of the incident shock wave is varied below 1.25, and the magnitude of impulse wave is measured using a pressure transducer mounted on a wedge probe. Instant images of the impulse wave are obtained by means of the Schlieren optical method. The present experimental results show that the helical vane considerably reduces the magnitude of the impulse wave and the vane effects are more remarkable for stronger incident shock wave.

• 항공우주기술
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• 제3권1호
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• pp.45-55
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• 2004

본 논문은 시간적분 자유후류 해석방법을 통해 팬-덕트의 공력해석을 수행하였으며 음향상사법 및 경계요소법을 이용하여 덕트에 의한 음향 산란 해석을 하였다. 또한 팬-덕트 내의 블레이드 장착 위치를 변화시키고 이에 대한 공력 및 자유음장해석을 수행한 결과 저소음화의 가능성을 보였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.70-77
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• 2004

Comprehensive investigation on the outlet's geometric shapes of a centrifugal blower with higher inlet resistance than an atmospheric pressure is carried out for improvements of its performance. Most unwanted behaviors of such blower are pulsating flows because of unbalance between inflows and outflows in a scroll casing. In order to reduce this undesirable phenomenon a triump is made for both the shape of outlet duct and an accessory structure inserted in the outlet port of the blower. The modification on the shape is concerned with the contraction of cross sectional area and the attached structure is for an intentional obstruction to cause a flow resistance. The details of the modification are examined for different cases and results. The methodologies for the work are performance evaluations including noise level and velocity measurements with PIV Consequently, the performance of improved system is close to that of the system operating with atmospheric pressure at the inlet.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.55-57
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• 1996

This paper presents an implementation of the adaptive ANC (Active Noise Control) system improving robustness. The system using the proposed algorithm shows a good performance of control, when the adaptive filter well does not work. We construct a real duct system and use DSP chip for experiment. Experimental results of the proposed algorithm prove the system to be superior than the conventional filtered-x LMS algorithm when the adaptive filter is out of order.

• 한국산학기술학회논문지
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• 제21권8호
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• pp.468-474
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• 2020

덕트는 FCU에서 생산된 냉난방 공기를 각 함 내 격실로 수송하기 위한 통로로 이용되는 통풍관을 의마한다. 덕트는 일반적으로 금속재질로 제작되고 있으나, 최근 함정에서는 금속 덕트의 단점을 보완하기 위하여 전투지휘실, 조타실, 음탐기, 조종실 등 주요 격실에 대하여 소음감소효과가 뛰어나고 격실 내에 공기를 골고루 전달할 수 있는 장점을 가진 천 덕트가 대체재로 사용되고 있다. 그러나 함정용 천 덕트는 성능요구조건이 엄격하여 국내에서 생산하지 못하고 있으며 해외에서 전량 수입하고 있는 실정이다. 이 연구에서는 천 덕트는 국산화를 통해 경제적 효과를 창출하기 위하여 국내 업체에서 개발한 천 덕트에 대하여 주요성능 요구조건을 검증하여 보았다. 소음감쇄성능에 대한 자체 검증이 완료된 국산화 천 덕트에 대하여 현재 건조중인 함정에 적용 가능여부를 확인하기 위해 공기투과성능과 방화성능 시험을 수행하여 구매요구사양서에 제시된 성능요구조건 충족여부를 검증하여 보았다. 시험결과 국산화 개발된 천 덕트는 공기투과성능 요구조건과 방화성능 요구조건을 모두 만족하여 건조함정에 적용하기 위한 주요 성능조건을 충족하는 것으로 확인되었다.

• 대한기계학회논문집B
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• 제21권1호
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• pp.89-98
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• 1997

Compression waves propagating in a high speed railway tunnel impose large pressure fluctuations on the train body or tunnel structures. The pressure fluctuations can cause ear discomfort for the passengers and increase the aerodynamic resistance of trains. As a fundamental research to resolve the pressure wave phenomenon in the tunnel, a steady theory of Chester-Chisnell- Whitham was applied to a simple shock tube with a sudden cross-sectional area reduction to model trains inside the tunnel. The results of the present theoretical analysis were compared with the experiments of the shock tube. The results show that the reflected compression wave from the model becomes stronger as the strength of incident compression wave and the blockage ratio increase. However, the compression wave passing through the model is not strongly dependent on the blockage ratio. The theoretical results are in good agreement with the experiments.

• 대한기계학회논문집B
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• 제21권9호
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• pp.1139-1148
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• 1997

Compression waves propagating in a high-speed railway tunnel develops large pressure fluctuations on the train body or tunnel structures. The pressure fluctuations would cause an ear discomfort for the passengers and increase the aerodynamic resistance of trains. As a fundamental research to resolve the pressure wave phenomenon in the tunnel, experiments were carried out by using a shock tube with an open end. A blockage to model trains inside the tunnel was installed on the lower wall of shock tube, thus forming a sudden cross-sectional area reduction. The compression waves were obtained by the fast opening gate valve instead of a conventional diaphragm of shock tube and measured by the flush mounted pressure transducers with a high sensitivity. The experimental results were compared with the previous theoretical analyses. The results show that the ratio of the reflected to the incident compression wave at the sudden cross-sectional area reduction increases but the ratio of the passing to the incident compression wave decreases, as the incident compression wave becomes stronger. This experimental results are in good agreements with the previous theoretical ones. The maximum pressure gradient of the compression wave abruptly increases but the width of the wave front does not vary, as it passes over the sudden cross-sectional area reduction.

• 한국산업보건학회지
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• 제3권2호
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• pp.213-226
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• 1993

The purpose of this study is to computerize the design of single source for a duct work system which is essential for the improvement of working places. There are different types of hood, such as general hood, push pull hood and canopy hood. And out of these three types, general hood and canopy hood were used as subjects of this study. The software used here was Quattro Pro 123 programm, and the hardware was IBM PS/SX(type 5510-SK4 S/N 83-05164). And the results are tabulated in