• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.903-909
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• 2001

Apartment and large residence buildings are necessary to ensure a comfortable noise/vibration environment. So. it must be performed a anti-vibration/noise evaluation at early design stage, such as utility room arrangement, machinery installation method and so on. In this paper. environment noise status on problem areas, which was issued by resident. was investigated to understand the noise transmission property generated from underground machinery room and to device a optimized countermeasure in order to enhance noise environment. Also, the measured noise levels before and after modification works are compared to confirm the effectiveness of proposed countermeasure.

• 한국정밀공학회지
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• 제20권9호
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• pp.151-158
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• 2003

The impulse noise of bullet after shooting in small arms has an effect on the hearing ability of human. Although a silencer has been developed for noise reduction in small arms, there is only a few researches about relationships between the sound pressure level and the auditory sense of human. In this study, the quantitative sound pressure levels are revealed by experimental measurements of impulse noise with each silencer type. And the performance evaluation for noise suppression of a silencer in small arms is carried out to reduce a serious loss of the hearing ability of the small arms user. It is concluded that the evaluated results can be utilized for checking sound pressure and data accumulation for new small arms design with silencer.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.358-363
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• 1997

The Operational Deflection Shape designates the motion pattern by which a structure vibrates under a specific operating condition. Modal Analysis is usually tested under test bench, but Operational Deflection Shape can be measured directly under real operating condition. It provide useful information for trouble-shooting and aid understanding and evaluation of the absolute dynamic behaviour of a machine or component. In this paper, It is analysed Excavator Upper Frame using Operating Deflection Shape.

• 대한기계학회논문집
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• 제11권6호
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• pp.1014-1025
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• 1987

본 연구에서는 기계요소중에서도 그 성능에 미치는 인자의 수가 많고 또 그 영향이 복잡하고 난해하며 아직도 경험적 요소가 수많이 남아있으면서도 공업적으로 매우 중요한 동력전달용 치차장치를 예로 들어 그 설계, 제작, 손상 및 트러블슈팅을 하기 위한 엑스퍼트시스템을 개발하려고 한다.

• 한국소음진동공학회논문집
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• 제26권7호
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• pp.795-805
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• 2016

Nonlinear normal modes(NNMs) is a branch of periodic solution of nonlinear dynamic systems. Determination of stable periodic solution is very important in many engineering applications since the stable periodic solution can be an attractor of such nonlinear systems. Periodic solutions of nonlinear system are usually calculated by perturbation methods and numerical methods. In this study, numerical method is used in order to calculate the NNMs. Iteration of the solution is presented by multiple shooting method and continuation of solution is presented by pseudo-arclength continuation method. The stability of the NNMs is analyzed using Floquet multipliers, and bifurcation points are calculated using indirect method. Proposed analyses are applied to two nonlinear numerical models. In the first numerical model nonlinear spring-mass system is analyzed. In the second numerical model Jeffcott rotor system which has unstable equilibria is analyzed. Numerical simulation results show that the multiple shooting method can be applied to self excited system as well as the typical nonlinear system with stable equilibria.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권12호
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• pp.520-526
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• 2005

Demands for the noise reduction of a transformer has been becoming an common issue because it has been used mainly at the residence area such as an apartment complex. This paper shows 2 trouble shooting examples that high noise sources were found out structural resonance of a transformer by 120Hz exciting frequency caused from magnetostrictive vibration of core. This paper presents that vibration data are very important to find noise source and how to avoid natural frequency of core and tank wall

• 한국산업보건학회지
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• 제23권3호
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• pp.261-265
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• 2013

The purpose of this study was to evaluate noise level exposures at different locations such as the left and right ears of the shooter, control room, waiting soldier location and drill ground. For this study, we visited two military rifle ranges and took measurements with a sound level meter (3M Quest SoundPro TM) at five different locations with values of Peak (dB(A)) and Max (dB(A)). The highest peak value of impulse noise level averaged 150.4 dB(A), ranging from 149.6 to 150.5 dB(A) at both the left and right ear sides. This result was significantly different between both left and right ear side locations and at other locations such as the control room, waiting soldier location, and drill ground (P < 0.001). Frequency of impulse noise exposure level showed that the left ear of shooter had the highest frequency (20 times) at over 150 dB(A). This study confirmed that there is a need for proper controls to reduce the amount of impulse noise exposure at military rifle ranges.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1993년도 춘계학술대회논문집; 한국과학연구소, 21 May 1993
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• pp.93-100
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• 1993

With increasing technology, requirement to car noise and related dynamics are getting competitive keypoint. Unfortunately, vibro - acoustic behavior of a car is nowadays only possible after development of prototypes. But, obviously, in the Area of Research, many of Industrials, Universities and research centers try to codevelop the design tools to predict the vibro-acoustic behaviors. At this stage, it is more realistic to represent the existing technologies in order for the engineer to get their own know-how to design and to Integrate existing techniques, to setup their test facility, and to develope some tools with which they can successfully predict noise levels of car in the design phase. Moreover, most of the theories which will be represented in this paper can be used in the design phase. At any way, finding the cause of trouble shooting is more urgent than the design of a car to the test engineer. In this paper, transfer path analysis, noise source identification, and the key test method of modal analysis is introduced. Later, if I get the opportunity to present in KSNVE, the approach method of modal analysis is introduced. Later, if I get the opportunity to present in KSNVE, the approach method of finding characteristics of joint and welding part will be introduced. Most parts of this paper was quoted from the papers of LMS.

• 한국소음진동공학회논문집
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• 제26권5호
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• pp.578-583
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• 2016

In order to provide a basis data for design of small arms and their silencer, an experimental study on firing noise of small arms was performed around the muzzle of a gun. For this experimental comparison analysis, the target small arms were included most operating small arms in our country. The sound pressure levels were measured at a certain distance which was predetermined according to US army firing test procedure, TOP 3-2-045. By this experimental study, the sound pressure levels of 5.56 mm caliber small arms are 143 dB ~ 145.4 dB and 7.62 mm caliber small arms are 144 dB ~ 145.2 dB. Between the heavy machine gun K12 and M60, the sound pressure level of K12 is slightly lower than M60.Also silencer for K14 snifer rifle was tested. Using this result, it has been found that the reduction effect of the silencer is 15.4 dB but the improvements of silencer performance in the high frequency range have to be studied later on.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.542-545
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• 2004

The vibration reduction process for the driver comfort of a forklift truck is studied in this study since the related driver comfort is a primary design target in the vehicle design recently. However, the underlying study for a vibration analysis regarding to the driver comfort is still an element stage. Thus, a preceding large work has to be needed to apply the CAE technology for the detail vehicle design, and it prevents the vehicle optimal design. To reduce the proceeding large works, the evaluated process and required data are comply with the accumulated trouble shooting experiences in this study. Since the driver comfort is a human related problem, the human vibration index associated with analysis vibration result is additionally introduced as a driver comfort judgement value.