• 한국정밀공학회지
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• 제22권2호
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• pp.53-59
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• 2005

In this study, the isolation system for multi-mechanism HIF (high impulsive force) device has been investigated. For this purpose, parameter optimization process has been performed based on the simplified isolation system model under constraints of moving displacement and transmitted force. The design parameters for multi-mechanism HIF device have been derived with respect to HIF system I and HIF system II, respectively. In order to implement the dynamic absorbing system, the dual stage hydro-pneumatic damper and magnetorheological damper with semi-active control scheme are considered. Finally, the performance of the designed prototype isolation system has been evaluated by experimental works under actual operating conditions.

• 한국항공우주학회지
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• 제39권9호
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• pp.832-838
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• 2011

본 연구는 달착륙선의 착륙장치 개발 연구로써 자기효과를 이용한 충격흡수장치를 제안한다. 충격흡수장치는 금속튜브와 피스톤 로드(piston rod), 피스톤 로드를 따라 가진되는 영구자석으로 구성되며 금속튜브와 영구자석사이에 존재하는 자기력과 상대운동에 의해 발생되는 와전류 효과 등의 자기효과를 이용하여 충격에너지를 분산 및 소산시킨다. 또한 자석을 같은 극을 마주보게 배치함으로써 코일 스프링과 유사한 충격흡수 효과를 얻을 수 있다. 이 장치는 구조가 단순하고 오일이나 가스의 사용이 불필요하므로 우주공간에서 사용이 용이하다. 자기 효과를 이용한 충격흡수장치의 감쇠와 스프링 특성을 전자기학 이론과 유한요소해석을 통하여 관찰하고 장치를 설계, 제작하여 실험을 수행한 결과와 비교분석하였다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 춘계학술발표논문집
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• pp.278-284
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• 2006

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2005년도 추계학술발표논문집
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• pp.317-324
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• 2005

• 한국산업융합학회 논문집
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• 제23권5호
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• pp.757-763
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• 2020

City gas buried pipes are managed by corrosion protection to prevent corrosion. In the case of the press-in section, the double pipe and the main pipe may cause corrosion under the influence of stray current, which can shorten the life of the pipes. In addition, if the insulator is filled in the press-in section, the press-in section itself is a single structure, and can be directly affected by external impact, and when the surrounding ground subsidence occurs, the stress may be concentrated, resulting in serious consequences. In this study, a serration-type shock absorber in the form of a sliding support was proposed as a new buried double piping construction method using EPS. The serration-type shock absorber can contribute to the improvement of the integrity of the buried double piping, as it can utilize the gas piping's own ductility and stress distribution characteristics with proper anti-corrosion management and shock-absorbing material properties by preventing contact inside the buried double pipe. However, for application to ground piping, there remains a task to supplement the vulnerability against fire due to the characteristics of EPS materials.

• Advances in aircraft and spacecraft science
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• 제5권3호
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• pp.319-334
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• 2018

In this study, the failure mode and energy absorption capabilities of a composite shock absorber device, during an emergency landing are evaluated. The prototype has been installed and tested in laboratory simulating an emergency landing test condition. The crash absorber presents an innovative configuration able to reduce the loads transmitted to a helicopter fuselage during an emergency landing. It consists of a composite tailored tube installed on the landing gear strut. During an emergency landing this crash absorber system should be able to absorb energy through a pre-designed deformation. This solution, compared to an oleo-pneumatic shock absorber, avoids sealing checks, very high values of the shock absorber pressure, and results to be lighter, easy in maintenance, inspect and use. The activities reported in this paper have become an attractive research field both from the scientific viewpoint and the prospect of industrial applications, because they offer benefits in terms of energy absorbing, weight savings, increasing the safety levels, and finally reducing the costs in a global sense.

• 대한치과보철학회지
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• 제35권1호
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• pp.118-129
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• 1997

The purpose of this study was to evaluate the shock absorbing effect of 4 restorative materials and intramobile connector. The damping effect of four restorative materials used to veneer test crown rigidly connected to IMZ implant and subjected to an impact force was measured. These materials included a gold alloy(stabilor G) : a noble metal ceramic alloy(Degudent H) : porcelain(Duceram) : composite resin(Dentacolor). In addition, this study compared damping effect of same restoretive materials after using polyoxymethylene intramobile connector(POM IMC). The result of this study suggest that : In case of using metal IMC 1. Veneered composite resin(group IV) reduced the impact force by 75%, when compared to an equivalent thickness of porcelain(group III). Group IV reduced the impact force by 87% and 89%, respectively, when compared to Stabilor G(group I) and Degudent H(group II). 2. The impact force recorded was higher for the alloy with the higher elastic modulus.(Stabilor G, group I, Young's modulus 107 Gpa, versus Degudent H, Group II, Young's modulus 95 Gpa) 3. It took the longest time for composite resin veneered group(IV) to reach to peak force when compared group I, II, III. In case of using POM IMC 4. The mean impact force recorded were reduced by 79%(group I), 78%(group II), 69%(group III), 84%(group IV), respectively, when compared to using metal IMC. 5. The time required to reach the peak force were increased by 78%(group I, II) 87%(group III), 34%(group IV), respectively, when compared to using metal IMC>.

• 대한기계학회논문집A
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• 제34권7호
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• pp.943-946
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• 2010

본 연구에서는 소형자전거의 핸들에 적용할 수 있는 전방 서스펜션을 제안하고 시뮬레이션을 통해 충격흡수 성능을 평가하였다. 서스펜션이 없는 경우, 기존의 전방포크서스펜션이 장착된 경우 그리고 제안된 핸들서스펜션이 장착된 경우 등 3가지 서스펜션 종류에 대해 인체모델을 이용한 주행시뮬레이션을 수행하여 각각의 완충성능을 비교평가 하였다. 시뮬레이션 결과 제안된 핸들 서스펜션의 경우 손과 머리에 전달된 가속도가 기존의 전방포크서스펜션이 장착된 경우보다 크게 측정되었지만 서스펜션이 없는 자전거의 경우보다는 현저히 작게 측정되었다. 이 같은 결과는 제안된 핸들 서스펜션이 상당한 완충 성능을 보여주었으며 이는 경량화가 중요한 소형자전거에 적용이 가능할 것으로 보인다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2007년도 춘계학술대회논문집
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• pp.285-297
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• 2007

As the demands of environment protection increase, the pulp mold container is developed to substitute for the plastic cushion materials like EPS(expanded poly styrene). The water-absorbing ratio, tensile strength and compressive strength of pulp mold are important factors to evaluate its shock absorbing characteristics. The study was performed to investigate the effects of the mechanical property changes on the various conditions of temperature and relative humidity for pulp mold containers made of mixed materials on ONP(old newspaper) and OCC(old corrugated container). This study also is evaluated the optimized mixing ratio of materials for making pulp mold by analyzing the changes of physical properties according to a various procured temperature and relative humidity conditions. The results show that the water absorption ratio of sample increased significantly, and tensile strength decreased $20{\sim}30%$, compressive strength decreased $10{\sim}20%$ by increasing relative humidity condition. And the results show that the ONP 50% and OCC 50% was optimized mixing ratio according to the samples.

• Elastomers and Composites
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• 제41권1호
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• pp.40-48
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• 2006

고무는 금속 및 플라스틱 재료와 달리 작은 하중에서도 큰 변형이 발생되며, 높은 변형 구간에서 탄성특성을 보이는 특징이 있다. 특히 충격흡수 특성이 금속 및 플라스틱보다 우수하므로 제진 및 충격 완충구조물로 널리 활용되고 있다. 충격하중을 받는 고무 구조물의 특성을 평가하기 위하여 자유 낙하형 충격시험기를 이용하여 충격실험을 실시하였으며, ABAQUS/Explicit를 이용하여 유한요소 해석을 수행하였다. 고무의 동강성은 충격펄스의 최대변형량과 충격지속시간으로부터 얻어진 진폭과 주파수를 적용하여 동특성 시험을 수행하고 WLF모델을 적용하여 높은 주파수 대역의 동강성을 예측하였다. 실험을 실시한 $0.3{\sim}l.5J$의 충격에너지 영역에서는 고무의 경도가 증가되면 충격흡수율이 감소되며, 충격에너지가 커질수록 충격흡수율은 감소하는 경향을 나타내었다.