• 항공우주시스템공학회지
• /
• 제11권6호
• /
• pp.34-41
• /
• 2017

기존 알루미늄 하니콤 코어를 이용한 착륙선 충격완충장치의 대체 방안으로서 실리콘 고무와 같은 초점탄성 재료의 다중압출 특성을 이용한 새로운 개념의 충격 완충장치를 고찰하였다. 초점탄성재료가 오리피스 단면을 통과하며 압출되는 과정에서 재료 변형에너지 및 하중-변위 특성이 기존 하니콤 코어 특성과 유사하여 충격 완충 성능을 극대화 할 수 있는 측면에서 유사성을 가지고 있음을 알 수 있었다. 본 논문에서는 충격완충장치의 설계 구현가능성을 평가하고, 에너지 변환을 통한 충격흡수 매커니즘을 이해하기 위하여 유한요소해석 및 준정적 압축시험 결과를 검토하였다.

• 한국항공우주학회지
• /
• 제45권11호
• /
• pp.951-966
• /
• 2017

본 연구에서는 세 가지 종류의 올레오식 2중 완충기 특성 비교를 위해 첫 단계 연구에서 제안한 수학적 모델을 이용하여 수치해석을 수행하고 완충 특성을 비교하였다. 각 올레오식 2중 완충기 모델에 대해 수치해석 알고리듬을 제시하였으며, 이를 MSC/ADAMS 상용 다물체 동역학 해석 소프트웨어의 사용자 서브루틴으로 구현하였다. 구현된 사용자 서브루틴을 활용하여 압축/신장시험 및 낙하시험에 대한 각종 수치해석을 수행하였으며, 해석 결과의 비교 분석을 통해 올레오식 2중 완충기 유형에 따른 완충거동 특성을 고찰하였다. 또한 결과로부터 항공기 착륙 요구조건에 맞추어 적절한 내부형상 변경 및 완충기 종류 선정을 통해 올레오식 완충기의 충격흡수 성능을 높일 수 있음을 확인하였다.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
• /
• pp.267-273
• /
• 2012

Solar reforming of methane with CO2 was successfully tested with a direct irradiated absorber on a parabolic dish capable of 5kWth solar power. And the new type of double-layer absorber-the front layer, porous metal foam which absorbs the radiation and transfers the heat from material to gas, and the back layer, catalytically-activated metal foam-was prepared, and its activity was tested by using electric furnace. Ni was applied as the active metal on the gamma-Al2O3 coated Ni metal foam for the preparation of the catalytically-activated metal foam layer. Compared to conventional direct irradiation of the catalytically activated metal foam absorber, this new type of double layer absorber is found to exhibit a superior reaction and thermal storage performance at the fluctuating incident solar radiation. In addition, unlike direct irradiation of the foam absorber, double layer absorber has better thermal resistance, which prevents the emergence of cracks caused by mechanical or thermal shock. The total solar power absorbed reached up to 3.25kW and the maximum CH4 conversion was almost 59%.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
• /
• pp.80-86
• /
• 2011

Solar reforming of methane with CO2 was successfully tested with a direct irradiated absorber on a parabolic dish capable of 5kWth solar power. And the new type of double-layer absorber - the front layer, porous metal foam which absorbs the radiation and transfers the heat from material to gas, and the back layer, catalytically-activated metal foam - was prepared, and its activity was tested by using electric furnace. Ni was applied as the active metal on the gamma-Al2O3 coated Ni metal foam for the preparation of the catalytically-activated metal foam layer. Compared to conventional direct irradiation of the catalytically activated metal foam absorber, this new type of double layer absorber is found to exhibit a superior reaction and thermal storage performance at the fluctuating incident solar radiation. In addition, unlike direct irradiation of the foam absorber, double layer absorber has better thermal resistance, which prevents the emergence of cracks caused by mechanical or thermal shock. The total solar power absorbed reached up to 3.25kW and the maximum CH4 conversion was almost 59%.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2013년도 춘계학술대회 논문집
• /
• pp.1405-1406
• /
• 2013

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2011년도 춘계학술대회 논문집
• /
• pp.1229-1230
• /
• 2011

• 한국자동차공학회논문집
• /
• 제19권2호
• /
• pp.57-65
• /
• 2011

In this paper, a hydropneumatic modeling and dynamic analysis of a heavy truck semi-active cabin air suspension system is presented. Semi-active cabin air suspension system improves driver's ride comfort by controlling the damping characteristics in accordance with driving situation. So it can reduce vibration between truck frame and cabin. Semi-active cabin air suspension system is consist of air spring, leveling valve and CDC shock absorber, and full cabin system are mathematically modelled using AMESim software. Simulation results of components and full cabin system are compared with experimental data of components and test results of a cabin using 6 axis simulation table. It is found that the simulation results are in good agreements with test results, and the hydropneumatic model can be used well to predict dynamic characterics of heavy truck semi-active cabin air suspension system.

• International Journal of Aeronautical and Space Sciences
• /
• 제15권3호
• /
• pp.335-343
• /
• 2014

An airbag is an important safety system and is well known as a safety system in cars during an accident. Airbag systems are also used as a shock absorber for UAVs to assist with rapid parachute landings. In this paper, the dynamics and gas dynamics of five airbag shapes, cylindrical, semi-cylindrical, cubic, and two truncated pyramids, were modelled and simulated under conditions of impact acceleration lower than $4m/s^2$ to avoid damage to the UAV. First, the responses of the present modelling were compared and validated against airbag test results under the same conditions. Second, for each airbag shape under the same conditions, the responses in terms of pressure, acceleration, and emerging velocity were investigated. Third, the performance of a pressure relief valve is compared with a fixed-area orifice implemented in the air bag. For each airbag shape under the same conditions, the optimum area of the fixed orifice was determined. By examining the response of pressure and acceleration of the airbag, the optimum shape of the airbag and the venting system is suggested.

• 한국소음진동공학회논문집
• /
• 제11권4호
• /
• pp.13-21
• /
• 2001

Electrorheological(ER) fluid is a kind of smart material with variable shear stress and dynamic viscosity under various electric field intensity. Electric field can control the damping characteristics of ER damper. The objective of this study is the analysis of the performance of ER damper and its application to shock absorber. Idealized nonlinear Bingham plastic shear flow model is used to predict the velocity profile between electrodes. Cylindrical dashpot ER damper with moving electrode is constructed and tested under various electric fields. The analytic and experimental results for damping force are compared and discussed. Drop test system using ER damper is prepared to identify transient vibration characteristics. The rebound is eased as the applied electric field increases. When semi-active control algorithm is applied, rebound phenomenon disappears and vibration energy level decays faster than the case of zero electric field.

• 한국소음진동공학회논문집
• /
• 제15권2호
• /
• pp.135-147
• /
• 2005

As automobile technology advances, a smoother ride with less noise is desired. In order to achieve these purposes, a study on the vibration and noise produced by a moving automobile was carried out and a model for tire vibration characteristics which influence the ride performance was developed. The model was verified through simulations and experiments. The developed model was then applied to a half car model and automobile vibrations were analyzed. The effects of tire design parameters on the automobile vibration energy were investigated. The results from laboratory and field tests confirm the validity of the analytical model. The 17-DOF half-car model was built to analyze automobile vibration. The characteristics of the nonlinear model for a shock absorber were applied to this model. The results from the present 17-DOF half car model incorporating the analytical tire model with tire design parameters, were compared with the 5-DOF half car model where the tire was modeled with linear springs. The results of the 17-DOF model are close to the experimental results. Using the 17-DOF model, the influence of tire design parameter were considered. According to the analysis results, the vibrations at seat/body/wheel were predicted by simulation and experiment.