• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.111-118
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• 2006

The Emergency Diesel Generator(EDG) is a very important piece of equipment for the safety of a Nuclear Power Plant(NPP). In this study, the operating vibration or three kinds or EDG system was measured. The target EDG systems art Yonggwang 5 unit, Ulchin 2 unit and Ulchin 3 unit. The Yonggwang 5 and Ulchin 3 unit EDG system is the same type but the foundation systems are different. One is an anchor bolt type and the other is a spring and viscous-damper type. The purpose of this measurement is for a verification of the vibration isolation effect according to the foundation system. As a result. it can he said that the spring and viscous damper system of the EDG performed well for the vibration isolation.

• 한국소음진동공학회논문집
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• 제20권9호
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• pp.791-796
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• 2010

Installing noise barriers is the most common method for reducing the highway traffic noise to the road side residential area. After the report about edge potential concept of a noise barrier, various types of noise reducing devices(NRDs) called "noise reducers" have been suggested for getting more shielding effect on the top of highway noise barriers. But, it has been doubtful about effect of the NRDs in field because there was no appropriate and unified method to estimate the acoustic performance by using field measurement of the NRDs in Korea. In this study, the authors have considered to setup a practical method to test and estimate the acoustic performance of NRDs. For eliminating the noise reduction effect of the NRDs height itself, the source and measuring points are adjusted as highly as the NRDs height. For the frequency weighting in the estimation of the NRDs effect, the highway noise spectra were measured at asphalt and concrete road side and then averaged for a unit spectral parameter.

• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.1104-1110
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• 2003

The present study investigates the hemorheological characteristics of blood flow with applying vibration to a non-aggregating red blood cell suspension. In order to obtain the non-aggregating RBC suspension, blood samples were treated with vibration at a specified condition, which viscosities were taken before and after the treatment, respectively. The viscosity of the blood samples after treatment was higher than before treatment. These treated blood samples were forced to flow through a capillary tube that was vibrated perpendicularly to the direction of the flow. The experimental results showed that vibration caused a reduction of the flow resistance of the non-aggregated blood. The reduction of the flow resistance was strongly dependent on both frequency and amplitude of vibration. These results show potential in treating various diseases in the microcirculation associated with blood cell aggregation.

• 한국소음진동공학회논문집
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• 제26권5호
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• pp.584-593
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• 2016

In this study, an improvement design method for reducing the vibration of fenders equipped in a tractor is proposed through the establishment of a finite element model and the topology optimization. As the original shapes of the parts cannot be altered, an improved design model was derived in which a stiffener was attached to the border of parts. Thus, the first resonance frequency was increased by approximately 16 Hz, which was confirmed to be the frequency interval for avoiding the idle and operating frequency of the engine. Finally the improved design model was applied to confirm the effect of vibration reduction. Therefore, it can be concluded that the improved design model of the tractor fender is effective at reducing vibrations of the tractor fender.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.369-374
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• 2001

It was estimated that the anti-vibration measures at the source location of railroad are the most active and effective ones. Among CWR(Continuously Welded Rail), elastic rail fastener, floating slab, ballast mat, under sleeper pad, etc. like these various kinds of measures in the source, under sleeper pad as an anti-vibration measure was constructed at the railroad track supporting structures in the Jeon-la Line. In this study, through the field measurement of vibration at the railroad track supporting structures and nearby the ground, the vibration reduction effect of under sleeper pad were evaluated by insertion loss. As a result, vibration reduction effects were 5.0∼12.5㏈ on the concrete slab of the bridge, 3.9∼7.5㏈ on the ground nearby the bridge respectively.

• 소성∙가공
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• 제25권6호
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• pp.373-378
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• 2016

Recent researches have reported that the superposition of ultrasonic vibrations in metal forming provides beneficial effects such as the reduction of forming load, flow stress and interfacial friction which improves the surface quality of end products. This paper presents experimental investigations on the effects of ultrasonic vibrations in upsetting tests of aluminum. The ultrasonic exciting system consists of piezoelectric transducer and resonator was designed and constructed to superimpose high frequency oscillation on the forming tools. Ultrasonic vibration-assisted upsetting tests were performed for three vibration modes five amplitudes, and the results were compared with those of conventional upsetting tests. The results showed that the superimposition of ultrasonic vibration reduces the upsetting load, and the load reduction is only dependent on the amplitude of the applied vibration regardless of deformation histories and vibration modes.

• 소음진동
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• 제10권5호
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• pp.830-837
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• 2000

This paper deals with an analysis and countermeasure of escalator vibration. The vibration characteristics of escalators are studied theoretically and experimentally to fine the main cause of severe vibration. The main source of vibration in escalators is found to be chordal effect due to the step chain and sprocket system. It is also found that the vibration become significantly large at so called no load condition, in which the load due to passengers, during down-moving, is equal to the resistive force in the driving system. Dynamic absorbers are implemented to suppress the vibration, A theoretical analysis is made to determine the appropriate dynamic absorber. Theoretical and experimental study shows that dynamic absorber is effective to suppress the vibration in escalators.

• International Journal of Automotive Technology
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• 제5권3호
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• pp.189-194
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• 2004

The viscoelastic layer material is widely used to control the noise and vibration characteristics of the panel structure. This paper describes the design technology of the effective vibration damping treatment using the concept of the equivalent parameter of viscoelastic layer materials. Applying the equivalent parameter concepts based on theories of shell, it is possible to simulate the finite element analysis of damping layer panel treatments on the vibration characteristics of the structure. And it is achieved the reduced computational cost and the optimal design of topological distribution for the reduction of vibration effect.

• 해양환경안전학회지
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• 제29권6호
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• pp.620-627
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• 2023

선내 소음은 선원의 거주성과 건강을 위한 중요한 요소 중의 하나로, 선내 소음을 줄이기 위한 노력이 활발하게 진행되고 있다. 소음 저감 방법에는 수동소음제어(PNC) 방법과 능동소음제어(ANC) 방법이 있다. 자동차, 항공기와 달리 선박에서는 ANC를 이용한 소음 저감 대책이 미미한 실정이다. 본 연구는 능동소음제어(ANC)와 같이 방음판과 고주파진동원을 이용하여 기관실에 발생한 소음을 줄이고자 하였다. 이를 위해 아크릴 상자를 이용하여 실험 모형을 만들었고, 4가지 조건별로 소음 저감 효과를 측정하였다. 실험 결과는 다음과 같다. 첫째, 방음판은 55 dB ~ 85 dB까지 모든 범위에서 소음 저감 효과가 있었다. 고주파진동원은 낮은 소음에서 효과가 없었으나, 70.8 dB(A)과 85 dB(A)와 같은 높은 소음에서는 효과가 있었다. 둘째, 방음판과 고주파진동원을 동시에 사용하는 경우에는 최대 -2.2 dB(A) 만큼의 소음 저감 효과가 있었다. 본 실험의 결과는 아크릴판으로 제작한 실험모형에서 얻은 결과로 철판으로 된 실제 선박과 다를 수 있다. 추후 연구에서 실제 선박에서 사용하는 철판(재질과 두께, 구조를 고려)을 이용하여 실험하고자 한다. 이 연구가 선박에 승선하는 선원들의 거주성 향상과 건강 증진에 도움이 되기를 기대한다.

• 우주기술과 응용
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• 제2권3호
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• pp.187-194
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• 2022

안테나의 고속 정밀 지향성 확보를 위해 동작되는 모터의 구동에 의한 외란의 크기는 극히 미소함에도 불구하고, 정밀 지향 성능이 요구되는 관측 위성의 영상 품질을 저해하는 주요 원인으로 작용하게 된다. 고해상도 관측위성의 지향 성능 향상을 통한 고해상도 영상정보 획득을 위해서는 지향성 안테나의 모터 구동시 발생하는 미소진동(Jitter)이 주요 임무 장비에 전달되지 않도록 적절한 진동절연 및 저감 설계가 요구된다. 본 논문에서는 실제 위성에 적용된 지향성 안테나 진동저감 장치에 대해 개발과정과 적용 전후의 미소 진동 저감 효과에 대해 살펴보고자 한다. 이 장치는 별다른 인터페이스 추가 장비 없이, 지향성 안테나 구동부 내에 있는 기어 하나만을 스프링 댐퍼 기어 형태로 교체함으로서, 발생되는 지터문제를 획기적으로 개선할 수 있는 방법으로 고안되었으며, 이 방식은 2015년에 발사된 서브미터급 고해상도 지구관측 위성에 처음으로 적용되어 발사되었으며, 현재까지 성공적으로 운용 중에 있다.