• Title/Summary/Keyword: 낙하/충격실험

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Impact Analysis of Printed Circuit Boards Using Finite Element Method (FEM을 활용한 회로기판의 충격 해석)

  • 박철희;이우식;홍성철;박용석;서정범
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1992.10a
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    • pp.141-146
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    • 1992
  • 본 연구에서는 먼저 낙하 충격을 받는 전자 제품을 수학적인 모델링을 행하 므로서 낙하 충격시 제품이 받게되는 충격력을 정량화하였고, 전자 제품내 많은 부품들의 낙하충격에 대한 동특성해석의 일환으로 핵심 부품인 PCB(printed circuit board)를 해석하였다. PCB 해석을 위하여 유한요소법을 사용하였고, PCB에 작용하는 half-sine pulse의 속도 변화에 다른 가속도 응 답 및 최대 충격가속도, 주기의 변화에 다른 PCB의 가속도 응답을 해석하였 다. 제시된 해석 기법은 낙하충격에 대비한 적절한 electric component의 layout및 최적의 PCB 취부조건등의 결정을 가능케 함으로써, 설계단계에서 낙하 충격을 고려한 PCB설계가 될 수 있도록 그 활용 방안을 제시하였고 반복된 낙하충격 실험을 줄일 수 있으므로 경비 절감 및 개발 소요기간도 절감할 수 있다.

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Impact properties of corrugated fiberboard box for the pears (배 골판지 포장상자의 충격특성)

  • 김만수;정현모;이영희;황용수
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 2002.02a
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    • pp.304-310
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    • 2002
  • 배 포장용 골판지 상자의 자유낙하 실험을 통하여 완충재로써의 골판지 상자에 대한 충격력을 분석하기 위한 시스템을 구성하고 계측 및 분석용 컴퓨터 프로그램을 작성하여 자유낙하에 의한 배 골판지 포장상자의 충격력을 분석하였으며, 배 골판지 포장상자의 낙하높이에 따른 배의 손상정도는 낙하높이가 높아짐에 따라 손상이 심하고 낙하높이가 낮은 25cm에서도 진동에 의한 손상지수보다는 훨씬 큼을 알 수가 있었다. 이것은 자유낙하에 의한 골판지의 충격력이 배에 전달되어 멍이 발생하는 것으로, 진동에 의한 변위 증폭 및 압상에 의한 손상보다 낙하 충격력에 의한 손상이 더 큰 것을 알 수가 있었으며, 배 골판지 포장상자의 적재 및 하역 작업시에는 낮은 낙하높이에서도 포장상자를 떨어뜨리지 않도록 주의를 하여야 할 것이다.

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Formulation on the Empirical Equation of the Cask Impact Forces by Dimensional Analysis (차원해석을 이용한 사용후 핵연료 수송용기의 충격력 실험식 공식화)

  • Kim Yong-Jae;Choi Young-Jin;Lee Young-Shin
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.18 no.3
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    • pp.245-254
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    • 2005
  • Radioactive material is used in the various fields. The numbers of transport for radioactive material have been gradually increased in both domestic and International regions. The safety of the cask should be secured to safely transport of radioactive material. The korean atomic law and the IAEA safety standards prescribe regulations lot the safe transport of radioactive material The cask for spent fuel is comprised of the body and the impact limiter. In this study, the empirical equation of the cask impact force is proposed based on the dimensional analysis. Using this empirical equation the characteristics of the impact limiter are analyzed. The results are also validated by comparing with the previous results of the impact area method and the finite element analysis. The present method can be used to predict the impact force of the cask.

Floor Impact Noise Characteristics Depending on the Experimental Conditions Using Impact Ball (실험조건에 따른 임팩트 볼의 바닥충격음 변화 고찰)

  • Lee, Won-Hak;Haan, Chan-Hoon
    • The Journal of the Acoustical Society of Korea
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    • v.30 no.2
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    • pp.92-99
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    • 2011
  • In Japan, bang machine has been considered to have problems about not only the impact force and frequency response which are different from the real impact sources such as children's jumping and running, but also damage in the wooden structure housing. Therefore, a new impactor for lower impact force to prevent demage in wooden structure housing was developed. The impact ball was adopted as the second standard impact source in JIS A 1418-2 and ISO 140-11. In the present study, floor impact sounds generated by impact ball with drop heights in four floors of mock-up building of Building Research Institute (BRI) similar to typical Japanese wooden structure housing were investigated and also compared to jumping sound. The results show that Impact ball sound dropped at 10 cm to 30 cm was most similar to jumping sound. And The impact sound levels at 250 and 500 Hz were more sensitive to drop height than other lower frequencies. The error that may occur from the difference of height of 10 cm up and down based on the standard drop height caused by the impact ball operated by human hands was approx. 1 dB or less only in its value of characteristic, but it must be carefully taken into Impact ball in the Korea Standard.

A Study on Evaluation to Safety of Fire-proof Safety Helmet (소방 안전모의 안전도 평가에 관한 연구)

  • 한응교;엄기원;박준서;이성우
    • Fire Science and Engineering
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    • v.5 no.3
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    • pp.5-14
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    • 1991
  • Now a days, according that the occurrence of industrial disaster is on the increase, the necessity of protective goods is increasing. Specially estimate of safety helmet for protect of head is very important. On this, in this paper, amplification ratio and natural frequencies of fire safety helmet and general safety helmet are estimated by falling impect test and frequency analysis. Also. trend of damping is estimated by using these test results. And we know that the fire safety helmet is more safe than general safety helmet for protect of head.

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A mite Element Modeling for the Puncture Drop Test of a Cask with the Failure of Impact Limiter (충격완충체의 효과를 고려할 수 있는 운반용기의 파열낙하시험 유한요소해석 방법)

  • Kwon, Kie-Chan;Seo, Ki-Seog;You, Gil-Sung
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.7 no.1
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    • pp.9-16
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    • 2009
  • Transport package for radioactive material should be structurally safe under puncture drop condition and its safety should be verified by test and numerical analysis. Most finite element analyses for puncture drop have been performed without modeling the impact limiter since failure is occurred in the materials of the impact limiter. This paper presents a new modeling methodology, where an element is eroded in case that the material's failure criteria are reached at the element's integration point, to investigate the effect of the impact limiter in the puncture process. The effectiveness of the proposed scheme is shown through the puncture drop analysis of hotcell transport cask, which is under design in KAERI. The results show that about 80 percent of the total impact energy is absorbed due to the deformation of impact limiter. Using the present method the puncture drop can be analyzed more accurately, but it would give conservative results compared to the actual test condition.

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An Experimental Study on the Slamming impact around Wedged type structure in accordance with the Weight and Height of the change (중량 및 높이변화에 따른 쐐기형 구조물 주위의 슬래밍 충격에 관한 실험적 연구)

  • Oh, Seung-Jin;Jo, Dae-Hawn
    • Journal of Navigation and Port Research
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    • v.39 no.1
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    • pp.77-82
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    • 2015
  • Slamming means that the hull hits the waves and receives impact pressure. This slamming effect may cause harm to people and when you put the hull at risk. so it is very harmful for cargo safety. Therefor slamming impact pressure should be fully considered in ship designing. In this study the model of wedged type structure are produced aimed to simulate a free fall that the experiments were carried out on different weight and free fall height. The flow field has been obtained by 2-frame grey level cross correlation PIV(Particle Image Velocimetry) method and experiment was divided into water entry and water exit. The impact pressure of free fall structure by a pressure acquisition system apply to dewetron system. The angles between a model and the water surface are adapted $15^{\circ}$ respectively. The weight change of models was given as 1.5, 1.8 and 2.0kg. To study slamming phenomenon for free fall height the experiments were carried out by the free fall height of 100, 200 and 300mm. The experimental value of the impact pressure according to the changes in weight was increase impact pressure in proportion to the increase in weight and higher free falling height has also influenced the increase in impact pressures.

Free-fall Force Measurement in a Shock Tunnel (충격파 풍동에서의 자유 낙하 장치를 활용한 힘 측정)

  • Park, Jinwoo;Chang, Won Keun;Park, Gisu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.6
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    • pp.463-467
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    • 2016
  • In this paper, acceleration and pressure exerted on a human model were measured under a supersonic condition in a shock tunnel. In order to measure these in an interference-free environment, free-fall technique with an electromagnet and a three-dimensional iron-powdered human model was used. Free-fall experiment was conducted at Mach 4 and the force acting on the model was obtained by calculating the displacement from the flow visualization images.

Suggestion of New Method for the Prediction of Shock Vibration (충격진동 예측방법에 관한 새로운 방법 제안)

  • Cho, Kyu-Yong;Kang, Choo-Won;Go, Jin-Seok
    • Explosives and Blasting
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    • v.26 no.1
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    • pp.15-21
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    • 2008
  • In case of estimating the shocking vibration during the blasting demolitions, the weight and falling height of the structure, that is a potential energy, had been considered. But, this study presented a new equation which used the impulse concerning a falling weight instead of potential energy as a method of predicting the shock vibration. In this experiment, the data of the impulse were compared with the data of the potential energy by performing the free-fall, and all data were comparatively analyzed by the regression analysis method. Also, the method of the superposition theory, which is calculated by the diminution ratio according to distance, the free-fall difference according to height, and the time giving the shock to the ground according to the breakdown pattern, was compared with the previous vibration data occurring from the blasting demolitions in the same conditions. As a result, this study suggests that the impulse and the method of superposition theory be applied as a method of predicting the shocking vibration. Therefore, these results could be expected to estimate the shocking vibration more accurately than the previous method.

The Evaluation of Shock Absorption Performance of Magneto-Rheological Elastomer Through the Drop Impact Test (낙하 충격 실험을 통한 자기유변탄성체의 충격 흡수 성능 평가)

  • Joeng, Kyeong Sik;Lee, Chul Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.92-93
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    • 2013
  • In this study, Shock Absorption performance of Magneto-rheological elastomer(MRE) is identified through the drop impact test. Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. The impact loads in MR elastomer were measured under weight of impactor. Experiment results are shown through the experiments to confirm the effect of shock absorption of MR elastomer. Thus, the MR elastomer can be applied to shock absorber used in area that shock occurs.

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