• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.60-65
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• 2014

Shelter system is applying to weapon systems as usage of performing specific mission with arranging several electronic equipments and operators. Recently the electronic equipments is changing from development products to COTS(Commecial on-the-shelf) for demonstrating high performance at low cost. As internal operators of shelter system conduct several missions for specific or long time in this the present situation, One of the most important element considering the best combat power is internal noise level. Therefore, I desire to analyze the features and foresee muliple noise level with test for conforming whether requirements of design is met or not in this research paper.

• 한국음향학회지
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• 제41권6호
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• pp.698-704
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• 2022

본 논문에서는 노즐 내부 유동의 소음원으로부터 발생되어 방사되는 공력 소음을 정량적으로 분석하였으며, 이를 외부 방사소음 결과와 비교하였다. 세가지 종류의 노즐 형상에 대해 내부 및 외부 유동을 정확히 예측하기 위해 고해상도 수치해석 기법인 비정상 압축성 대와류모사(Large Eddy Simulation, LES) 기법을 사용하였다. 와류소음원(Vortex Sound Source)을 통해 유동소음원을 확인하였으며, 이를 통해 노즐 내부 형상에서 주요 유동소음원의 분포를 확인하였다. 노즐 내부 유동의 와류소음원 레벨과 외부 방사 소음의 예측결과 및 측정결과와 비교하였으며, 이를 통해 정량적 분석을 검증하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.838-843
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• 2001

Internal damping plays an important role in some rotor dynamic systems with the use of various materials for shafts, for example, composite material. However, although the effects of internal damping have been investigated for a couple of decades, there are several different internal damping models in use, none of which are accepted as the most reliable model. The purpose of this paper is to compare the results of dynamic analysis of rotor systems with several different internal damping models. The exact dynamic element method is used to formulate and analyze the problem. The simulation results provided in this paper may be useful for the dynamic analysis of high rotor systems subject to significant internal damping.

• 한국가정과학회지
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• 제1권2호
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• pp.61-74
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• 1998

The purpose of this study is to investigate residents subjective opinion of the noise on the low-rise multifamily house in U.S.A. The results of this study can be applied for the prevention of noise when planning cities, roads, and multifamily houses in Korea. The subjects of this study are three kinds of multifamily houses and their 109 residents in Athens, U.S.A. The results of this study are as follows. The residents felt the noise from lawn mowers and the sound from filter fans of air conditioners were higher than in the other external noise. The residents daily activities were disturbed a little by the external noise. Of the internal noise, the air home sound was recognized a little by residents. They only felt a moderate sound level from the building services of the solid borne sound. They suffered worse from noise in the summer and they felt worse from 16∼20 o'clock due to noise. The residents who were living in town houses felt better than those in the other multifamily houses. (Korean J Human Ecology 1(2):61∼74. 1998)

• 한국소음진동공학회논문집
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• 제12권10호
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• pp.758-765
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the Korean high speed prototype test train(HSR 350X). The object of this study was 3 kinds of cars, trailer car(TT2), motorized car(TMI ) and power car(TPI) and the predicted noise was for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from manufactures. Some of noise sources which were not available in the project team, were chosen by experiences of ODS. Internal noise level of each car was predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated for each section of the car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is the (floor in terms of structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TMI are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TMI are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.917-923
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the KHST test train. The object of this study was 3 kind of cars; trailer car(TT2), motorized car(TM1) and power car(TP1) and the predicted noise was calculated for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from each manufactures. Some of noise sources which were not available in project team, were chosen by experiences of ODS. Internal noise level of each car were predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated of each section of car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is floor in terms or structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TM1 are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TM1 are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• 한국주거학회논문집
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• 제10권2호
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• pp.203-212
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• 1999

The purpose of this study is to evaluate the Korean residents' subjective opinion of the noise on the lowrise multifamily house in America. The results of this study can be applied for the prevention of noise when planning cities, roads, and multifamily houses in Korea. The subjects of this study are three kinds of multifamily houses and their 124 Korean residents in Athens, America. The results of this study are as follows. The Korean residents felt the noise from lawn mowers and the sound of filter fan of air conditioners were higher than all the other external noise. They were disturbed a little by the external noise. The air borne sound was recognized a little by Korean residents but they only felt moderate sound of building services and household equipment from the solid borne sound of the internal noise. They suffered worse from external noise in the summer and they felt worse from 8～12 o'clock due to external noise and 20～24 o'clock due to internal noise. The Korean residents liked the sound of birds or insects, the sound of cars and trains. However many Korean people in Athens disliked the sounds of birds or insects and lawn mowers more than these sounds in Korea. The Korean residents who were living in the apartment houses felt better than those in the other multifamily houses.

• International Journal of Fluid Machinery and Systems
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• 제2권1호
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• pp.80-91
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• 2009

In this study, a prediction theory for specific noise that is the overall characteristic of the fan has been proposed. This theory is based on total pressure prediction and broadband noise prediction. The specific noises of two forward curved fans with different number of blades were predicted. The flow around the impeller having 120 blades (MF120) was more biased at a certain positions than the impeller with 40 blades (MF40). An effective domain of the energy conversion of MF40 has extended overall than MF120. The total pressure was affected by the slip factor and pressure loss caused by the vortex flow. The suppression of a major pressure drop by the vortex flow and expansion of the effective domain for energy conversion contributed to an increase in the total pressure of MF40 at the design point. The position of maximum relative velocity was different for each fan. The relative velocity of MF120 was less than that of MF40 due to the deviation angle. The specific noise of MF120 was 2.7 dB less than that of MF40 due to the difference in internal flow. It has been quantitatively estimated that the deceleration in the relative velocity contributed to the improvement in the overall performance.

• 전기전자학회논문지
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• 제24권4호
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• pp.1129-1135
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• 2020

배터리를 사용함에 따라 노화가 진행되면 배터리의 충전 가능 용량을 나타내는 State of Health(SoH)가 줄어들게 된다. 배터리 모니터링 시스템(BMS)에서 SoH를 추정하는 것이 매우 중요하며, 이를 위해 배터리 내부 저항을 측정하는 방법이 많이 사용된다. 일반적으로 배터리에 특정한 주파수의 전류원을 인가하고 전압응답을 측정하여 내부저항을 연산한다. 충전기가 동작할 경우 전압응답에 충전 고조파 잡음이 발생하여 저항 측정의 정확도가 떨어진다. 본 논문에서는 충전잡음의 영향을 제거하기 위하여 강인한 배터리 내부저항 측정 알고리즘을 제안하였다. 전류원 신호와 전압응답 신호를 일정한 주기 동안 적분하여 잡음을 제거하는 방법으로 우수한 정확도와 안정된 연산결과를 보였다. 무정전 전원장치용 BMS에 적용하여 제안한 방법의 유용함을 입증하였다.

• 소음진동
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• 제8권2호
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• pp.239-250
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• 1998

Traditionally, intake noise from internal combustion engine has not recevied much attention compared to exhaust noise. But nowadays, intake noise is a major contributing factor to automotive passenger compartment noise levels. The main objective of this paper is to identify the mechanism of generation, propagation and radiation of the intake noise. With a simplest geometric model, one of the main noise sources for the intake stroke is found to be the pressure surge, which is generated after intake valve closing. The pressure surge, which has the nonlinear acoustic behavior, propagates and radiates with relatively large amplitude. In this paper, unsteady compressible Navier-Stokes equations are employed for the intake stroke of axisymmetric model having a single moving cylinder and a single moving intake valve. To simulate the periodic motion of the piston and the valve, unsteady deforming mesh algorithm is employed and Thompson's non-reflecting boundary condition is applied to the radiation field. In order to resolve the small amplitude waves at the radiation field, essentially non-oscillatory(ENO) schemes with an artificial compression method (ACM) are used.