• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.5-6
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• 2014

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2007년도 한국우주과학회보 제16권2호
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• pp.123.1-123.1
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• 2007

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.666-666
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• 2013

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.382-383
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• 2013

• 한국소음진동공학회논문집
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• 제18권5호
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• pp.533-540
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• 2008

In this study, a new slab system where a part of precast slab is connected each other by viscoelastic material is proposed and numerical analysis is performed to evaluate the effect of the connection between the material and PC slab on the vibration and noise control. Substructuring is introduced to develop the equation of motion for the slab system. In addition, the optimal properties of viscoelastic material are investigated. For the performance evaluation of the new slab system, the sound power and acceleration responses of the slab are compared with those of two way slab and one way slab, respectively. Numerical analysis results show that the sound power of the new slab system can be reduced by viscoelastic material significantly.

• 한국소음진동공학회논문집
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• 제18권2호
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• pp.247-254
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• 2008

Resilient materials are generally used for the floating floors to reduce the floor impact sound. Dynamic stiffness of resilient material, which has the most to do with the floor impact sound reduction. The resilient materials available in Korea include EPS(styrofoam), recycled urethane types, EVA(ethylene vinylacetate) foam rubber, foam PE(polyethylene). glass fiber & rock wool, recycled tire, foam polypropylene. compressed polyester, and other synthetic materials. In this study, we tested dynamic stiffness of resilient material and floor impact sound reduction characteristic to a lot of kinds of resilient materials. It was found that dynamic stiffness of multi-layered damping material could be estimated if know value of each layer that compose whole structure. And the test showed that the amount of the heavy-weight impact sound reduction appeared by being influenced from this dynamic stiffness of resilient material. The dynamic stiffness looked like between other resilient materials, a similar to the amount of the heavy-weight impact sound reduction was shown.

• 한국소음진동공학회논문집
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• 제24권7호
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• pp.517-524
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• 2014

Micro-vibration induced by on-board equipments such as fly-wheel and cryogenic cooler with mechanical moving parts affects the image quality of high-resolution observation satellite. Micro-vibration isolation system has been widely used for enhancing the pointing performance of observation satellites. In general, the micro-vibration isolation system requires a launch locking mechanism additionally to guarantee the structural safety of mission payloads supported by the isolation system with low stiffness under launch environment. In this study, we propose a passive launch and on-orbit vibration isolation system using shape memory alloy mesh washers for the micro-vibration isolation of spaceborne compressor, which does not require the additional launch locking mechanism. The basic characteristics of the isolator were measured in static and free vibration tests of the isolator, and a simple equivalent model of the isolator was proposed. The effectiveness of the isolator design in a launch environment was demonstrated through sine vibration, random vibration and shock tests.

• 한국소음진동공학회논문집
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• 제13권9호
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• pp.679-687
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• 2003

Shock wave reduction in electrorheological(ER) smart structures is studied. ER insert is a composite structure comprising two elastic outer layers between which is sandwiched layer of ER fluid. When a voltage is applied across the outer layers. the shear modulus and the loss factor of the ER fluid are enabled, and thus the dynamic properties of the composite structure is altered. For the shock wave reduction in a hull mount of a submerged structure, ER inserts are made on the hull mount structure. To investigate the ER insert shape. many types of ER insert pattern are considered. Modal test of ER insert structures is performed to obtain the mode shapes, natural frequencies and the acceleration transmissibility. The acceleration transmissibility is reduced at such a frequency region when an electric field is applied. It is observed that the natural frequencies and mode shapes can be tunable by applying electric field. The ER-inserted hull mount is installed in an integrated system and the overall performance of shock wave reduction is tested. The possibility of shock wave reduction in the hull mount is demonstrated.

• 한국소음진동공학회논문집
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• 제18권11호
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• pp.1192-1198
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• 2008

In this paper, the vibration and shock of an HDD car-holder are reduced through vibration analysis and a structural modification. In order to identify the exciting frequency components of vibration and shock, vibration signals are measured and analyzed from the wind shield or dashboard. In addition, the modal test for the current HDD car-holder is performed to investigate the dynamic characteristics of the car-holder. From these experiments, it is found that the exciting frequencies coincide to the natural frequencies of the car-holder. For the purpose of avoiding resonance, some FEM simulations are carried out and then structural modifications are made for the car-holder. Based on the results of simulations, a prototype of new car-holder are manufactured and tested to demonstrate the reduction of vibration and shock. It is verified by the test that a considerable amount of vibration and shock are reduced.

• 한국항공우주학회지
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• 제42권4호
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• pp.284-290
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• 2014

성공적으로 달 탐사를 수행하기 위해서는 달착륙선의 안전한 착륙이 보장되어야 한다. 그러므로 안전한 착륙을 저해하는 착륙 시 충격하중을 감소시키기 위해서는 효율적인 달착륙선 충격흡수장치를 설계해야 한다. 또한 더욱 현실적인 달착륙선 설계를 위해서는 달 토양의 특성을 고려하는 것이 중요하다. 이에 본 논문에서는 달 토양의 특성을 반영한 달착륙선 착륙 해석 모델을 구축하고, 효율적인 충격력 감소를 위해 달착륙선의 충격흡수장치에 대한 최적설계를 수행하였다. 최적설계는 메타모델 기반의 순차적 근사 최적설계기법을 이용하여 수행하였으며, 최적설계 결과로 부터 본 연구에서 사용된 최적화 방법을 통해 달착륙선에 가해지는 충격력을 효과적으로 저감시킬 수 있음을 확인하였다.