• Title/Summary/Keyword: 압력변위

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Low-velocity Impact Damage of a Thick Graphite/Epoxy Case (Graphite/Epoxy로 만든 두꺼운 관의 저속 충격손상에 관한 연구)

  • 김형원;윤영주;나성엽
    • Journal of the Korean Society of Propulsion Engineers
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    • v.4 no.2
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    • pp.31-38
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    • 2000
  • Pressure vessels by composite materials were damaged sometimes during manufacturing or assembling. The state and the size of damage by low-velocity tests were investigated in this paper. Impactors of various masses and various tup shapes were dropped freely in the range of 120mm height to 700mm height. Compared with hemispherical tup of 12.7mm diameter, for hemispherical tup of 25.4mm diameter the size of surface dent was smaller but the size of delamination was bigger.

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The hydrostatic actuation test on flexible seal of KSLV-I Kick Motor (KSLV-I 킥모터 플렉시블 씰 수압 구동 시험)

  • Kim, Byung-Hun;Kwon, Tae-Hoon;Cho, In-Hyun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.11a
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    • pp.153-156
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    • 2009
  • The pitch and yaw axis controls of Kick Motor, KLSV-I second propulsion system, was provided by the flexible seal that consists of alternate laminate of natural rubber and composite reinforcements between forward and aft ring. A hydrostatic actuating test has been conducted to evaluate a performance of the manufactured flexibke seal before it is assembled at the nozzle. Through the tests, we have verified an actuation torque and axial displacement of the flexible seal according to pressure variation. The actuation torque and axial displacement of all flexible seal is shown below 60kgf-m/deg at without pressure and 6mm at MEOP respectively.

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The Analysis of Lateral Movement at the Top of Retaining Wall in the Downtown Area (도심지 옹벽 상단에서의 수평변위에 관한 사례분석)

  • Bae, Yoon-Shin
    • Journal of the Korean GEO-environmental Society
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    • v.10 no.3
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    • pp.63-71
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    • 2009
  • The movement of in-situ walls has become very important as construction in large cities moves upward, instead of outward. Tall structures typically have deep excavations not on1y to provide extra space for parking, but also to reduce the potential settlement of the building. These large excavations require a robust bracing system to resist the lateral earth pressures as the depth increases. Methods to predict deflections of the retaining systems are of utmost importance because wall movements allow potentia1 settlement of adjacent structures. Case studies will be analyzed and measured waI1 def1ections will be compared with predictions from empirica1ly derived charts.

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Implementation of Strain Imaging Modality in Medical Ultrasonic Imaging System (초음파 의료 영상 시스템에서 탄성 영상의 구현)

  • Yoon Ra-Young;Kwon Sung-Jae;Bae Moo-Ho;Jeong Mok-Kun
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.42 no.3 s.303
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    • pp.53-62
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    • 2005
  • This paper proposes a method of measuring and visualizing the elasticity distribution of the human soft tissue to detect tumors or cancers which have been difficult to diagnose in conventional medical ultrasonic B-mode images. To measure the stiffness of soft tissue, first, pressure is applied to deform the tissue being imaged, and then the amount of mechanical displacement is determined from correlation coefficients obtained from ultrasonic data downconverted into the baseband. We confirmed the feasibility of imaging tissue stiffness by computer simulation and experiment.

초정밀 표면측정기술의 동향

  • 김승우
    • Journal of the Korean Society for Precision Engineering
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    • v.10 no.1
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    • pp.22-27
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    • 1993
  • 산업기술의 발달에 따라 각 분야마다 정밀한 부품을 요구하고 있다. 이는 이들 부품이 시스템의 성능에 영향을 미치고 있기 때문이다. 부품의 정도는 길이정도와 표면의 정도를 모두 의미한다. 길이정도는 부품의 상대적 크기정도를, 표면정도는 3차원 형상정도를 나타낸다. 이들 부품의 정도를 평가하기 위해서는 반드시 측정이라는 방법이 수행되어야 하며, 측정은 요구되는 측정정도에 따라 이에 상용되는 방법으로 행해지게 된다. 요구되는 측정정도는 시간이 지남에 따라 점차 증가되고 있다. 이 러한 경향은 그림1의 시대에 따른 측정정도를 보면 확인할 수 있다. 시대에 따라 측정정도는 급격히 증가하고 있고 현재의 측정은 초정밀측정이라 말하는 약 0.1nm의 정밀도를 갖고 있다. 측정정도에 따라 표면측정기술도 여러가지 방법이 행해지고 있는데 이들 측정방법은 크게 접촉식 측정방법과 비접촉 측정 방법으로 나눌 수 있다. 대표적인 접촉식 측정방법으로는 촉침식 측정방법을 들 수 있다. 이 방법은 다이아몬드 촉침을 표면상에 접촉하여 주사이동하게 하고 이때 표면의 요철에 따른 촉침의 상하운동을 고성능 변위센서를 이용하여 표면형상을 측정하는 것이다. 이는1nm의 수직분해능을 갖고 측정이 가능 하다. 이 방법은 표면에 접촉함으로 인해 신뢰성이 높지만, 표면의 접촉압력으로 인해 표면의 손상 우려가 있다. 이런 이유로 현재 비접촉 측정방법이 주목받고 있다. 표면측정을 실현하는 데에는 광학 기술이 적극적으로 활용되고 있으며, 최근에는 물리학의 원리들이 도입되고 있다. 본 글에서는 이러한 측정기술의 기본원리를 소개하고 각 기술이 응용되는 예를 소개하고자 한다.

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Dielectric Relaxation Properties of DMPC Organic Thin Films for Nanotechnology (나노기술을 위한 DMPC 유기박막의 유전완화특성)

  • Chol, Young-Il;Cho, Su-Young
    • 전자공학회논문지 IE
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    • v.49 no.1
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    • pp.7-11
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    • 2012
  • In this paper, evaluation of physical properties about dielectric relaxation phenomena by the detection of the surface pressures and displacements current on the monolayer films of phospolipid monomolecular DMPC using pressure stimulus. As a result, It is found that the phospolipid monolayer of dielectric relaxation takes a little time and depend on the molecular area. When electric bias is applied across the manufactured MIM device by the deposition condition of phospolipid monomolecular, it is found that be characteristic of insulation generated it wasn't breakdown when the higher electric field to impress by increase of deposition layers.

Structural Analysis of Gasket and GDL for Enhanced Performance of PEMFC (고분자 전해질 연료전지 가스켓 및 GDL의 구조 해석)

  • Yoon, Jin-Young;Park, Jungsun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.7
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    • pp.642-650
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    • 2008
  • In this paper, structural behavior of Gasket and GDL of a PEMFC stack is studied to improve the performance and to secure the safety. In the Gasket analysis Mooney-Rivlin strain energy function is used to consider hyperelasticity of load and displacement. The material properties is determined by testing specimens of the gasket at uni-axial and equi-biaxial mode and compared with finite element analysis results. By measuring a thickness change, the material property of GDL is determined. The pressure drop of a unit cell is measured along the channel for the clamping force. A cross sectional change of channel base on the experimental data is obtained experimentally and compare with FEM analysis results.

Fretting Corrosion Behavior of Silver-Plated Electric Connectors with Constant Displacement Amplitude (일정 변위 진폭조건에서의 은도금한 커넥터의 미동마멸부식 거동)

  • Oh, Man-Jin;Kim, Min-Jung;Kim, Taek-Young;Kang, Se-Hyung;Kim, Ho-Kyung
    • Tribology and Lubricants
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    • v.30 no.2
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    • pp.99-107
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    • 2014
  • Fretting corrosion tests are conducted with a constant displacement amplitude using silver-plated brass coupons to investigate the effect of contact pressure on fretting corrosion. Three behaviors are identified based on the change in electric resistance and friction coefficient during the fretting test period, and the identified behaviors are dependent on the magnitude of the applied load. The failure cycle ($N_f$) with an electric resistance of 0.1 D cannot be achieved due to the adhesion behavior of the metal and metal contact under the higher applied load of 0.45 N. This suggests that an average contact pressure higher than 159 MPa for the silver-coated connector is desirable to gain an almost infinite lifetime. The relationship between the electric contact resistance (R) and the average contact pressure (p) can be written as $p=106.2{\times}{\Omega}^{-1.5}$.

Geological and Geophysical Surveys for Determining Causes of Rack Slides (암반사면 사태의 원인규명을 위한 지질조사 및 전기비저항 탐사)

  • 황학수;이태섭;기원서;박종오;문창규;최정환
    • The Journal of Engineering Geology
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    • v.11 no.3
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    • pp.295-301
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    • 2001
  • Geological and geophysical surveys were performed to examined the cause of the rock-mass slide occurred at the opening site of the Wanglim tunnel of the Seoul-Pusan High Speed Railway. The results of geophygical survey and geometrical analysis for the geological structures indicate that the rock-mass slide was triggered by the heavy rainfall which increases the groundwater level and results in high pore pressure in the N60$^{\circ}$ E-trending major fractured zone of the slope, and that the foliation dipping toward the vertical open face of the slope acted as a main sliding plane during movement.

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Numerical Study on the Strength Safety of a Fuse Cock Valve (퓨즈콕 밸브의 강도안전성에 관한 수치적 연구)

  • Kim, Chung Kyun
    • Journal of the Korean Institute of Gas
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    • v.19 no.5
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    • pp.1-6
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    • 2015
  • In this paper, the strength safety of a fuse cock main body has been analyzed by the finite element method. The stress and displacement behaviour characteristics have been investigated for thickness variations at the region of (T) between a ball valve and a fuse cock safety connector. The FEM analyzed results recommend that the optimized thickness at the region of (T) is from 1.55mm to 1.6mm for the supplied gas pressure of 1.5~3.5MPa. This is considered for the optimized strength safety and light weight of a fuse cock main body.