• Composites Research
• /
• v.17 no.4
• /
• pp.53-60
• /
• 2004

This paper describes a method for a falling weight impact test to estimate the impact energy absorbing characteristics and impact strength of CFRP laminate plates based on considerations of stress wave propagation theory. The absorbed energy of T300 orthotropic composites is higher than that of quasi-isotropic specimen over impact energy 6.8J, but in case of using T700 fiber, much difference does not show. Also, absorbed energy of T300 orthotropic composites, which are composed of the same stacking number and orientation became more than that of T700 fiber specimen; however there was no big difference in case of quasi-isotropic specimens. The delamination areas of the impacted specimen were measured with the ultrasonic C-scanner to find correlation between impact energy and delamination area. The fracture surfaces were observed by using the SEM (scanning electron microscope) through a low-velocity impact test in order to confirm the fracture mechanism.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.12
• /
• pp.64-69
• /
• 2002

In this study, the optimal dynamic isolation system for gas operated combat weapon has been investigated. For this purpose, firstly, the dynamic behavior of human induced by firing operations has been analyzed through a series of experimental works using the devised test setup. The characteristics of linear impulse has been compared under some conditions of support system. In order to design the optimal dynamic isolation system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2012.05a
• /
• pp.141-142
• /
• 2012

다운엔더 개념설계요건 설정을 위해서 PWR $16{\times}16$ SF집합체 제원을 분석하였다. 또한 수직에서 수평으로 전환될 때 충격량을 최소화하기 위해서 모의집합체 충격실험을 수행하였다. 그 결과 수직에서 수평으로 회전되는 각속도(30초/$90^{\circ}$)를 고려할 때 평균값은 약 0.1 g, 최대 약 0.3 g 정도가 되어 거의 충격을 받지 않음을 알 수 있다. 주요 설계요건으로 그리이드(grid)에 가해지는 수평클램프(clamp) 힘은 240kg, 하부노즐에 가해지는 수직클램프 힘은 900kg 이내로 하였다. 다운엔더의 개념설계를 위해서 기구학적 특성을 반영하였고, 전환시간을 30초/$90^{\circ}$로 하였다. 원격 유지 보수성을 향상하기 위하여 Solid Works 프로그램 툴(tool)을 이용하여 5개의 주요 모듈을 구성하였고, SF 집합체 다운엔더 개념을 3D로 설계하였다.

• KLA journal
• /
• v.12 no.11
• /
• pp.12-15
• /
• 1971

1차 잡지는 과학정보 전달의 모체로서 또 과학의 한 사회제도(Social institution)로서 그 역사적 역할을 수행하여 왔음을 비롯하여, 여기서는 특히 공간되는 학술기록으로서의 기능, 또 연구달성을 공표해주는 최고기구로서의 기능에 중점을 두어 이를 고찰한다. 따라서 일차잡지의 역할에 대한 각종의 개혁론이 종래의 전통적 기능에 반하여 충격적으로 논해지고, 아울러 고도로 전자계산기화한사회에 임하여, 그 가능한 미래상을 예측해 본다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.04a
• /
• pp.534-539
• /
• 2014

• Monthly Korean Chicken
• /
• s.130
• /
• pp.98-99
• /
• 2006

개그맨 김형곤씨의 갑작스런 죽음에 충격을 받은 많은 중년 남성들이 '심근경색'에 이목을 집중하고 있다. 같은 날 슬로보단 밀로셰비치 전 유고연방 대통령이 감방에서 사망했고, 그 전날에 성낙합 서울 중구청장이 집무실에서 숨졌는데, 이들의 사인 또한 급성 심근경색. 최근엔 우리나라의 40대 돌연사 비율이 경제협력개발기구(OECD) 국가 중 최고라는 통계까지 발표된 바 있다. 돌연사 공포증을 불러일으키고 있는 이 증상의 원인과 대책은 무엇일까.

• Composites Research
• /
• v.16 no.4
• /
• pp.66-73
• /
• 2003

The importance of understanding the response of structural composites to impact and CAI cannot be overstated to develop analytical models for impact damage and CAI strength predictions. This paper presents experimental findings observed from quasi-static lateral load tests, low velocity impact tests. CAI strength and open hole compressive strength tests using 3 mm thick composite plates($[45/-45/0/90]_{3s}$- IM7/8552). The conclusion is drawn that damage areas for both quasi-static lateral load and impact tests are similar and the curves of several drop weight impacts with varying energy levels(between 5.4 J and 18.7 J) follow the static curve well. In addition, at a given energy the peak force is in good agreement between the static and impact cases. It is identified that the failure behaviour of the specimens from the CAI strength tests was very similar to that observed in laminated plates with open holes under compression loading. The residual strengths art: in good agreement with the measured open hole compressive strengths. considering the impact damage site area, an equivalent hole. The experimental findings suggest that simple analytical models for the prediction of impact damage area and CAI strength can be developed on the basis of the failure mechanism observed from the experimental tests.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.4
• /
• pp.629-636
• /
• 2001

In order to investigate the possibility of impact punching in brittle materials, an experimental setup was developed. In the setup, a long bar as a punch was used to apply the impact load to the specimen plate and measure the applied impact force during the impact punching process. Impact punching tests with various shape of punches were performed in soda-lime glass and silicon wafer under a different level of contact pressure. The damage appearance after the impact punching was examined according to the applied contact pressure. The minimum contact pressure required for a complete punching in glass specimens without development of radial cracks around the punched hole was sought at each condition. The minimum contact pressure increased with increasing the thickness of specimens and decreasing the end radius of punches. The profile of impact forces was measured during the impact punching experiment, and it could explain well the behavior of the punching process in brittle material plates. The measured impact force increased with increasing the contact pressure applied to the plates.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.2
• /
• pp.211-222
• /
• 2011

In this paper a structural analysis of the PWR(pressurized water reactor) canister with 102cm diameter is carried out to evaluate the structural safety of the canister for the impact force occurring at the moment of collision with the ground in the falling plumb down accident from the carriage vehicle which may happen during the canister handling at the spent nuclear fuel disposal repository. For this, a rigid body dynamic analysis of the canister is executed to compute the impact force using the commercial CAE system, RecurDyn, and a nonlinear structural analysis is performed to compute stresses and deformations occurring inside the canister for this computed impact force using the commercial FEM code, NISA. From these analysis results, the structural safety of the canister is evaluated for the falling plumb down accident from the carriage vehicle due to the inattention during the canister handling at the repository. The rigid body dynamic analysis performed assuming the canister as a rigid body shows that the canister falls plumb down to the ground in two types. And also it shows that early collision impact force is the biggest one and following impact forces decrease gradually. The height of the carriage vehicle in the repository is assumed as 5m in order to obtain the stable structural safety evaluation result. The nonlinear structural analysis of the canister is executed for the biggest early impact force. The structural analysis result of the canister shows that the structural safety of the PWR canister is not secured for the falling plumb down accident from the moving carriage vehicle because the maximum stresses occurring in the cast iron insert of canister are bigger than the yield stress of the cast iron.

• Journal of Aerospace System Engineering
• /
• v.18 no.3
• /
• pp.56-64
• /
• 2024

In this study, a drop impact tester was developed to comprehensively conduct basic testing and academic research on the drop impact characteristics of aerospace structures. A drop tester enables accurate assessment of the dynamic stresses and deformations that occur when an aircraft collides with the ground, thereby enabling the verification of important design factors, such as safety and mechanical strength. The drop tester consists of an electromagnet to attach and drop the test object, a crane to adjust the drop height of the test object, and a drop support structure for vertical drops. Numerical analysis of the drop test object for the test was performed, and basic tests were performed using the drop impact tester. Through the analysis and test results, the structural shape of the landing gear was analyzed, and the behavior of each part was evaluated.