• Title/Summary/Keyword: 충격면적

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Aircraft Impact Analysis of Steel Fiber Reinforced Containment Building (강섬유를 적용한 원전 격납건물의 항공기 충돌해석)

  • Seo, Dong Won;Noh, Hyuk Chun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.26 no.2
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    • pp.157-164
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    • 2013
  • In this study, the structural performance of nuclear power plant containment buildings, which are made of steel fiber reinforced concrete(SFRC) and subject to aircraft crash, is examined by finite element analyses. The applied loads by aircraft crash against the buildings are modeled using Riera impact load function and by the varying aircraft contact area with respect to time. CSCM concrete model in LS-DYNA is employed to model SFRC. The parameters for the material model are determined from SFRC strength prediction models. Based on the volume ratio of steel fiber in SFRC, the structural performance of nuclear containment buildings subject to aircraft crash are analysed using a commercial finite element analysis program LS-DYNA. The safety assessments of the buildings subject to the crash are discussed and the effectiveness of SFRC for nuclear power plant containment building on the increase of aircraft crash resistance is also evaluated.

A Study on the Solar Panel Deployment of a Satellite (인공위성 태양전지판의 전개에 관한 연구)

  • Seo, Jong Hwi;Han, Sang Won;Park, Tae Won;Chae, Jang Su;Seo, Hyeon Seok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.4
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    • pp.53-59
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    • 2003
  • Strain Energy Hinge(SEH) has been used in Korea Multi-purpose Satellite(KOMPSAT) series to deploy the solar panel due to the good record of reliability. However, when it reached a desired deployment position, a large buckling force is applied to the main body. This may cause structural damage and also affect control of the satellite. Therefore, reliable dynamic analysis for the deployment system is required at a design stage. Moreover, various mission of a satellite has made the size of solar panels got bigger, so elastic effect has to be considered seriously to get more precise analysis results. In this paper, a dynamic analysis method to predict the deployment is verified by KOMPSAT-2 deployment test.

Breakaway Fracture Energy(BFE) of Indented Type Bolt for Breakaway Sign Supports (분리식 지주 단부장치에 이용되는 인덴티드 타입 볼트의 분리파괴에너지)

  • Ko, Man-Gi;Kim, Kee-Dong;Jun, Sung-Min;Sung, Jung-Gon
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.4
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    • pp.39-45
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    • 2008
  • Breakaway support for small signs of size $0.293\;m^2{\sim}0.360\;m^2$ using indented tube type bolt of D12 mm with 6 mm inner diameter has been developed and the structural strength of the support system for the wind load was verified through static shear and tension tests. One important value in understanding the dynamic behavior of sign post and impact vehicle is the fracture energy of the sign support. In this study, fracture energy needed to break the sign support was estimated by pendulum test and computer simulation using LS-DYNA program. Support system composed of 3 indented bolts was found to sustain the 43.1 kg$\sim$51.2 kg wind load safely. Fracture energy for one indented bolt was measured as 163.3J from the pendulum test, and was calculated as 153J from the LS-DYNA simulation. The closeness between these two values verified the validity of the simulation model.

Analysis of High Velocity Impact on SFRC Panels Using ABAQUS (ABAQUS를 이용한 강섬유보강 콘크리트 패널의 고속 충돌 거동 해석)

  • Son, Seok-Kwon;Jang, Seok-Joon;Yun, Hyun-Do;Kim, Yong-Hwan
    • Journal of the Korea Concrete Institute
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    • v.28 no.2
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    • pp.141-148
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    • 2016
  • This paper employed finite element method (FEM) to study the dynamic response of Steel Fiber-Reinforced Concrete(SFRC) panels subjected to impact loading by spherical projectiles. The material properties and non-linear stress-strain curves of SFRC were obtained by compression test and flexural test. Various parametric studies, such as the effect of fiber volume fraction and thickness of panels, are made and numerical analyses are compared with experiments conducted. It is shown that protective performance of concrete panels will be improved by adding steel fiber. Area loss rates and weight loss rates are decreased with increasing fiber volume fraction. Also, penetration modes can be expected by FEM, showing well agreement with experiment. Results can be applied for designing the protection of military structures and other facilities against high-velocity projectiles.

A Study On Cause Analysis and Improvement About Malfunction of Proximity Sensor Exposed High Temperature (근접센서의 고온 고장발생에 관한 원인분석 및 개선 연구)

  • Park, Jin-Saeng
    • Transactions of the KSME C: Technology and Education
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    • v.3 no.3
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    • pp.175-181
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    • 2015
  • Because internal space of combat vehicle reachs about $80^{\circ}C$ at high temperature period, Proximity Sensor exposed high temperature and humidity, which has function to sense the distance and transfer signal for control unit, have enlarged sensing distance and finally locked on. Malfunction of sensing itself occur frequently, therefore we carried out cause analysis and improvement. We accomplish improvement activity secondly. Through-out many trial and error, we find out that malfunction of sensor occur at high temperature circumstance. To improve, the another Emitter Coil is added to increase voltage difference and improve sensing accuracy about 5~10 times. And we accomplish design improvement to dull temperature and humity change after increasing molding surface to add vibration and shock resistance. We prove that the improved product do not fail after enduring 136hr at $85^{\circ}C$ temperature and 85% relative humidity circumstance chamber.

Regulation in Shear Test Method for BGA of Flip-chip Packages (플립칩 패키지 BGA의 전단강도 시험법 표준화)

  • Ahn, Jee-Hyuk;Kim, Kwang-Seok;Lee, Young-Chul;Kim, Yong-Il;Jung, Seung-Boo
    • Journal of the Microelectronics and Packaging Society
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    • v.17 no.3
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    • pp.1-9
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    • 2010
  • We reported the methodology for the shear test which is one of the evaluation procedure for mechanical reliability of flip-chip package. The shear speed and the tip height are found to be two significant experimental parameters in the shear test. We investigated how these two parameters have an influence on the results, the shear strength and failure mode. In order to prove these experimental inconsistency, simulation using finite element analysis was also conducted to calculate the shear strength and to figure out the distribution of plastic energy inside of the solder ball. The shear strength decreased while the tip height increased or the shear speed decreased. A variation in shear strength due to inconsistent shear conditions made confusion on analyzing experimental results. As a result, it was strongly needed to standardize the shear test method.

An Experimental Study on the Effects of Tabs and Small Proturbances Inside Nozzle on Supersonic Jet Flowfield (노즐 탭과 노즐 내부 낮은 돌출부가 초음속 제트유동장에 미치는 영향에 관한 연구)

  • Jin, Won-Jin;Cho, Chang-Kwon;Lee, Yeol;Yoon, Woong-Sup
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.5
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    • pp.24-31
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    • 2002
  • The effects of vortex generators, in the form of small delta-shaped tabs or thin tapes at an axi-symmetric supersonic nozzle exit, on the characteristics of supersonic jet flowfields are investigated by Schlieren images and Pitot-tube measurements. Small tabs as small as 1 % of the nozzle exit area can introduce streamwise vortices and produce a significant effect on the jet flowfield downstream of the nozzle. The effect is stronger for the cases of under-expanded jet than over- and perfect-expanded cases, introducing a larger flow entrainment. The effects of the angle of tabs with respect to the flow direction are also investigated, and for over-expanded jet cases, it is found that the tabs bended toward upstream can weaken the interaction strength and remove the Mach disc in the jet flowfield. Introduction of small proturbances inside the nozzle surface by attachment of thin tapes is also found to change the pressure distribution in the circumferential direction of the flowfield. Its effect is also found to be dependent on the jet expansion ratio.

The Limit of the Continuum Assumption Based on Compressible Flow Structures in an Axisymmetric Micro-Thruster Used for a Satellite (인공위성용 축대칭 소형 추력기의 압축성 유동 구조 계산에 의한 연속체 가정의 적용 한계)

  • Kwon, Soon-Duk;Kim, Sung-Cho;Kim, Jeong-Soo;Choi, Jong-Wook;Lee, Kee-Man
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.04a
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    • pp.281-285
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    • 2007
  • The flow characteristics in the thruster should be analyzed considering its geometry and the pressure ratio to estimate its performance and etc. This paper suggests the computational result of an axisymmetric real nozzle for the altitude control of a satellite to find out the application limit that the assumption of continuum mechanics holds. The steady non-reacted compressible flow field in the unstructured grid system is computed and analyzed with varying the environmental pressure (or the degree of vacuum) under the fixed pressure ratio in a real thruster of which the area ratio of exit to throat is 56. The assumption of the continuum mechanics is not approved when the environmental pressure is reduced less than $10^{-3}$ atm.

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Biomechanical Application of Plantar Pressure Distribution for Walking on Uneven Rocky Surface (Uneven Rocky Surface 이동 시 압력분포를 적용한 운동역학적 활용)

  • Chung, Yong-Min
    • Korean Journal of Applied Biomechanics
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    • v.19 no.2
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    • pp.387-397
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    • 2009
  • Physical activity has been increased with increased leasure time. Specifically, due to our mountainous geographical benefits, people actively participate in hiking and climbing as regular daily activities. Thus, more stable and comfortable hiking boots are required to walk on uneven and sloped rocky surface for a long period of time. 5 male subjects were recruited for testing planter pressure patterns of four different conditions(barefoot, classic hiking boot, stiffness 60 and stiffness 65). Tested hiking boots(stiffness 60 and stiffness 65) consists of the multiple pieces of outsoles as they are designed for a better shock absorption. In the results, some positive aspects of stiffness 60 and stiffness 65 such as wide contact area and powerful propulsive patterns at take off was observed compared to the classic hiking boots. Therefore, biomechanical development of hiking related clothes and footwear as well as equipment would be beneficial for people who enjoy hiking to maximize their quality of activities.

유전체장벽 방전구조의 비접촉식 저온 대기압 면방전 플라즈마를 이용한 빵곰팡이의 살균효과

  • Yu, Yeong-Hyo;Kim, Seong-Hui;Park, Gyeong-Sun;Choe, Eun-Ha
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.519-519
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    • 2013
  • 본 연구에서는, 전기적 충격이 없고 넓은 면적을 동시에 처리할 수 있는 형태의 유전체 장벽 방전(DBD: Dielectric Barrier Discharge)을 이용한 대기압 저온 플라즈마 장치를 제작하고 이를 이용하여 빵 곰팡이(Neurospora crassa) 살균에 대한 기본 분석을 하였다. 실험에 사용한 저온 대기압 면방전 플라즈마의 파워는 사인파 교류전압을 인가하여, 방전전압은 1.4~2.3 kV, 방전전류는 20~30 mA의 값을 가지며, 전압과 전류의 위상차는 약 80도의 기울기 차이가 난다. 이때의 출력은 약 4 W를 가지며, 공랭식 쿨러를 이용하여 유전체의 열을 배출하였다. 시료대의 온도 측정결과 방전과 동시에 쿨러를 작동할 경우 최대 10분에서 37도를 넘지 않았다. 장치에서 발생하는 플라즈마에 의한 O3의 양은 플라즈마 발생부로부터 10 mm 이내에서 약 25~30 ppm 이 측정되었으며, NO나 NO2 는 거의 검지되지 않았다. 증류수(Deionized water)속에 담긴 빵 곰팡이(Neurospora crassa) 포자를 면방전 플라즈마 발생장치로 처리하였을 때, 포자의 발아율은 처리시간 및 출력파워가 증가함에 따라 급격히 감소하였으나 VM (Vogel's Minimal) 배양액에 넣고 플라즈마 처리를 한 경우에는, 증류수의 결과와 달리 살균효과가 미비함을 보였다. MTT 측정법 또한 같은 경향성을 보였으며, 이를 통해 포자를 둘러싸고 있는 환경이 플라즈마의 살균효과에 영향을 미치는 것으로 보인다. 본 실험을 통해, 유전체 장벽을 이용한 면방전 플라즈마 발생장치가 플라즈마 제트(jet)와 달리 직접적인 플라즈마 접촉 없이도 미생물 살균이 가능하다는 것을 보았으며, 처리대상의 생체용액과 같은 주변 환경에 영향을 받음을 알 수 있었다. 또한 면방전 플라즈마 장치로부터 발생하는 O3과 같은 활성종들이 빵 곰팡이의 비활성화에도 역할을 할 수 있음을 알 수 있었다.

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