• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.46-56
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• 1999

A semi-actively controlled impact system which adjusts an impulse exerted by the external impact is studies. The main control variables are internal pressure difference inside the cylinder and the shock absorber displacement while it travels. Compared to a conventional one so called a passive system with a variable orifice inside the cylinder, a semi-actively controlled system utilizes an external orifice controlled by a highly fast responding electrical proportional valve. This device overcomes the temperature and viscosity change due to continuous operating and keeps the desired pressure difference and displacement in every operation. In this article a new prototype impact system is designed and manufactured based on a semi-actively control system. Through computer simulations and experiments, we verify the possibility of controlling the shock absorber pressure and displacement. After investigating the control performance a modified semi-actively controlled system with better control performance is also proposed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.377-384
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• 1998

The crushable front part of the conventional TGV is composed of 3 energy absorption zones; retractable coupler, protective headstock and honeycomb structure. This frontal part must absorb about 80% of the energy that should be done in a cra shworthy design. The conventional TGV can absorb 2MJ impact energy by the frontal end, but 5MJ is the design target for energy absorption in the next generation TGV. To accomplish this design goal, a new concept of design is necessary for energy absorbing components. In this paper, the design concept of the tube expansion energy absorber will be proposed and analyzed. The crash analysis of the energy absorber are performed by comparing the value of the theoretical equation wi th the simulation calculated from the commercial nonlinear FE-Code ‘PAM-CRASH’ S/W.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.734-735
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• 2008

Shock absorber for rotorcraft landing gear should absorb landing impact during landing and isolate vibration to fuselage during taxiing. Double stage oleo-pneumatic shock absorber is known to have better performances than single stage oleo-pneumatic shock absorber. This paper deals with the z-direction translational acceleration at mass center, roil and pitch angular acceleration of fuselage for single and double stage oleo-pneumatic shock absorber at nose landing gear when a 6DOF rigid model is taxiing on the pound.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.789-790
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• 2012

• 한국전산구조공학회논문집
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• 제33권4호
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• pp.255-261
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• 2020

본 논문은 충격을 줄이기 위해 효과적인 충격완충장치를 구성하는 방법을 제안했다. 기존의 충격완충장치는 폴리에틸렌으로만 만들어졌지만, 새로운 충격완충장치는 외측에는 폴리에틸렌, 내측에는 고밀도 재료로 구성하였다. 충격은 내측과 외측 물질 사이의 밀도 차이가 더 클 때 줄어들었다. 2층 구조의 외측으로 설계하기 위해 알루미늄, 티타늄, 구리를 선택하였다. 가장 밀도가 높은 구리에서는 충격 감소가 가장 좋았으며, 기존 충격완충장치보다 최대 감가속도는 43%, 충격량은 51% 감소하였다. 4층, 6층 충격완충장치의 경우, 충격량은 줄였지만, 최대 감가속도는 증가하였다. 신관은 가장 큰 충격으로부터 살아남아야 하며 나머지 충격파는 임계값을 초과하지 않으므로, 본 논문은 폴리에틸렌-구리를 사용한 2층 구조용 충격완충장치를 제안하였다.

• 수산해양기술연구
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• 제25권1호
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• pp.24-28
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• 1989

주진동계인 외팔보의 자유단에 부진동계인 부가질량을 설치하여 부가질량의 크기와 충격 틈새 및 접촉면적을 변화시켜 그때의 진동진폭 특성을 실험함으로써 밝혀진 결과들을 요약하면 다음과 같다. 1) 부가질량의 상하 충격작용이 계의 진동진폭 감소에 상당히 큰 효과가 있으며 일종의 충격감쇠기로써 사용할 수 있음이 실험적으로 확인되었다. 2) 부가질량이 같을 때 충격틈새를 적절히 조정함으로써 진동진폭을 감소시킬 수 있다. 3) 충격 틈새가 일정할 때, 부가질량이 클수록 진동진폭은 감소하지만, 특정 조건에서는 부가질량이 작아도 진폭 감소효과가 크다. 4) 부가질량과 충격틈새가 일정한 조건에서 그 틈새가 작을 때 (1mm, 2mm) 부가질량의 접촉마찰면적이 클수록 진동진폭은 감소한다. 5) 계의 진동진폭 감소가 클 때, 주진동계와 부가질량의 진동진폭에는 위상차가 발생하며 충격감쇠 효과가 가장 클 때 위상차도 최대로 된다. 6) 일반적으로 부가질량이 클수록 진폭은 감소한다. 향후의 연구과제로서 충격시의 소음을 감소시키며 감쇠작용을 증가시키기 위해 접촉면에 적절한 방진고무를 설치하여 그때의 진동 감소 특성을 구명할 것이 요구된다. 이러한 일련의 기초연구를 통하여 목적으로 하고 있는 충격식 동흡진기의 설계 및 이에 대한 실험을 수행할 것이다.

• Structural Engineering and Mechanics
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• 제23권5호
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• pp.487-504
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• 2006

Several new versatile two-dimensional p-version finite elements are developed. The element matrices are integrated analytically to guarantee the accuracy and monotonic convergence of the predicted solutions of the proposed p-version elements. The analysis results show that the convergence rate of the present elements is very fast with respect to the number of additional Fourier or polynomial terms in shape functions, and their solutions are much more accurate than those of the linear finite elements for the same number of degrees of freedom. Additionally, the new p-version plate elements without the reduced integration can overcome the shear locking problem over the conventional h-version elements. Using the proposed p-version elements with fast convergent characteristic, the elasto-plastic impact of the structure attached with the absorber is simulated. Good agreement between the simulated and experimental results verifies the present p-version finite elements for the analyses of structural dynamic responses and the structural elasto-plastic impact. Further, using the elasto-plastic impact model and the p-version finite element method, the absorber of the T structure on the Qiantang River is designed for its collision protection.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.137-140
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• 2003

Impact of Automotive GMT(Glassfiber reinforced Mat Thermoplastic) Bumper for '5Mhp Barrier Test'was simulated using ls-dyna. The FE model consists of foam which is energy absorber, bumper beam and stay etc. Bumper intrusion and deflection was compared with the experimental results. Effects of uncertainty of material property and deviation of impact velocity were considered and results were compared with those of base design. Effects of number of integration points through th thickness was also investigated.

• 천문학회보
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• 제40권1호
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• pp.75.3-75.3
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• 2015

Large area infrared surveys are often accompanied with follow-up optical spectroscopic surveys that has a significant legacy value even for other areas of research. Using these spectral database, we have performed a search for MgII absorption lines in the optical spectrum of background quasar. Over the ~4deg2 of AKARI North Ecliptic Pole survey field and Spitzer First Look Survey field, 18 and 16 MgII absorber systems are identified respectively. The redshift range for the background quasars was 1.0<$z_{qso}$<3.4, while the redshift range for the absorber was 0.6<$z_{abs}$<1.6. Galaxies responsible for MgII absorptions are identified in the deep optical images (CFHT r-band), yet the identification still remains ambiguous for 60% of the systems due to the limited image depth and the source crowdedness. The impact parameter ranges 20-60kpc, and the rest-frame equivalent width of MgII absorption ranges $0.7-4{\AA}$. The most critical part in the identification of MgII absorber galaxies is the existence of deep optical images in addition to the high S/N quasar spectrum with R>3000.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.250-254
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• 2011

Main role of landing gear is to absorb the energy which is generated by aircraft lanidng and ground maneuvering. Generally, in order to absorb the impact energy during landing, oleo-pneumatic type shock absorber is used for aircraft landing gear. Oleo-pneumatic type shock absorber has a good energy absorbing efficiency and is light in weight because its structure is relatively simple. For the landing gear development, it is necessary to conduct drop test in order to verify shock absorbing performance. In the drop test, first, gas spring curve verification tests are conducted. Then, limit and reserve energy absorption drop tests are performed based on the STANAG 4671. The drop tests results with performance analysis results are presented.