• Title/Summary/Keyword: 압력분포

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A study on the sliding rigid indentor over the viscoelastic layer supported by the elastic half-space (탄성체로 기대된 점잔성체층에서의 강성체의 운동해석)

  • Nam, J. W.
    • Journal of the korean Society of Automotive Engineers
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    • v.5 no.3
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    • pp.56-63
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    • 1983
  • 강성체로된 견인물체가 탄성무한경면으로 지지된 점탄성층 위를 미끄러져 갈 때 접촉구간에서의 압력분포와 마찰 특성을 고찰하였다. 즉, 접촉구간에서의 강성체의 모양과 압력분포에 관한 적분 방정식을 구하고, 점탄성층의 두께가 접촉구간에 비하여 충분히 두꺼울 때 압력분포와 마찰계 수의 근사해를 구하였다. 압력분포의 모양은 점탄성층의 물성을 표시하는 지수값, 즉 .alpha.<1/2, .alpha.=1/2, .alpha.>1/2에 따라서 크게 다르다. 한편, 수치해석에 의하면 마찰 계수에 대한 근 사해는 강성체의 미끄럼 속도, 점탄성 층의 두께, 탄성체의 영율 (E$_{o}$ )과 점탄성층의 시효 성탄성계수 (E$_{v}$ )의 차, 즉 E$_{o}$ /E$_{v}$ 에 따라 변화함을 알 수 있다. 즉, 탄성체가 점탄성층에 비하여 딱딱하면 할수록, 또 강성체 속도가 느리면 느릴수록 마찰계수는 작아진다. 그리고 불성의 지수(.alpha.)가 커지면 커질수록 근사해의 수렵 속도는 느려지게 되고 지 수(.alpha.)가 1에 가까워지면 점탄성층의 탄성효과는 점성효과에 비하여 거의 무시할 수 있으며 근사해는 의미가 없어지게 된다.

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초고층 건물에서의 연돌효과로 인한 압력분포 및 문제점

  • Jo Jae-Hun;Yeo Myeong-Seok;Kim Gwang-U
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.35 no.5
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    • pp.6-17
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    • 2006
  • 초고층 건물의 설계 및 시공단계에서 고려되어야하는 연돌효과로 인한 압력분포와 제반의 문제점 고찰을 통하여 건설관련 설계자, 시공자 및 HVAC 엔지니어에게 유용한 정보를 제공하고자한다.

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Development of pressure measuring system for powered-wheelchair (전동휠체어 압력분포 측정시스템 개발)

  • Kil, S.K.;Lee, S.C.;Kim, T.W.;Hwang, J.H.;Hong, E.P.;Han, Y.H.;Lee, J.S.
    • Journal of rehabilitation welfare engineering & assistive technology
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    • v.7 no.2
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    • pp.109-115
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    • 2013
  • In this paper, we developed pressure mesuring system for powered wheelchair and tried to validate the usefulness of developed system by pressure measuring experiment with 3D motion analysis. This system consist of 64ch seat FSR(Force Sensitive Resistance) sensor unit, 30ch*2 armchair FSR sensor unit, analog and digital hardware board, 2ch rotary encoder unit and realtime signal processing & display S/W. And each data acquired from this system has sampling frequency of 12bit, 10Hz. Pressure measuring experiment for 10 persons who use wheelchair in real life was performed in the 3D vision analysis room. From the experiment, we obtained result that the center line of body inclined to outside direction during powered-wheelchair rotate any direction.

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Effects of Gastrocnemius Muscle Length on the Dynamic Balance and Antero-posterior Pressure Distribution of Foot (장딴지근 길이가 동적 균형 및 발바닥의 앞뒤 압력 분포에 미치는 영향)

  • Lee, Won-Hwee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.6
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    • pp.150-157
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    • 2019
  • The purpose of this study was investigate the effect of gastrocnemius(GCM) muscle length on the dynamic balance and antero-posterior pressure distribution of foot. Thirty subjects were recruited and each subject was classified with control experimental and control group according to GCM muscle length. The experimental group included subjects with shortness of GCM muscle length, the control group included subjects with normal length of GCM. The dynamic balance and antero-posterior pressure distribution of foot were measured by Biorescue equipment. To evaluate dynamic balance, we collected data of limit of stability in antero-posterior direction. We analyzed the data by using independent t-test. The alpha level was set 0.05. The results showed that the dynamic balance and antero-posterior pressure distribution of foot were significantly different between two groups (p<0.05). This study suggests that the shortness of GCM affects anterior limited of stability in dynamic balance and anterior pressure distribution of foot. Therefore, it is important to maintain optimal GCM muscle length for normal balance ability and prevention of musculoskeletal disease.

길이가 유한한 선접촉의 탄섬유체윤활

  • 박태조;김경웅
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1986.11a
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    • pp.47-51
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    • 1986
  • 로울러 베어링의 로울러는 길이방향으로 적당하게 Profiling하여 양단부에서 발생하는 응력집중을 줄이고 있다. 로울러와 레이스간의 접촉을 단순한 탄성접촉문제로 해석하는 경우에는 유막의 개념이 없어서 로울러와 레이스 사이의 압력분포와 유막형상을 정확하게 나타내기가 어려우므로 탄성변형과 압력에 따른 윤활유의 점도 변화를 고려한 탄성유체윤활(EHL)해석이 필요하다. 대부분의 해석은 무한장 로울러로 취급하는 것이 보통이며 실제의 로울러에 해당하는 유한한 길이의 선접촉 EHL 해석은 Mostofi & Gohar 및 Kuroda & Arai의 해석 정도이나 각각은 수렴하중이 작거나 로울러의 길이가 아주 짧은 경우에 해당한다. 본 연구에서는 FDM과 Newton-Raphson method를 이용하여 길이가 유한한 실제 크기의 Profiled 로울러에 대한 EHL상태에서의 압력분포와 유막형상을 보다 하중이 온 경우에 대해서 구하고자 한다.

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펌프 위치 선정 (배관내 압력분포)

  • 정진문
    • 월간 기계설비
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    • s.61
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    • pp.23-29
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    • 1995
  • 열원기기와 공조기등을 연결하는 물배관식에는 여러 가지 방식이 있으며, 이는 배관의 기능 및 용도에 따른 각종 설계요소를 비롯하여 에너지 절약 측면 또는 내구성 향상을 위한 배려등에 의하여 결정되어지고 있다. 그러면 강제순환 배관계통에서 장치내의 펌프위치는 어떤 영향이 미치는지 한사례를 통하여 펌프가 열원기기의 전$\cdot$후에 설치되었을때 배관내의 압력분포도를 작성하고, 이에 대한 분석을 통하여 우리가 간과하기 쉬운 펌프 위치선정에 대한 주의점 및 배관내의 압력분포에 대한 유의사항등을 알아 보기로 한다.

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Pressure distribution near truncated POD attached on hydrofoil vessel (Hydrofoil 선박용 POD 변형에 따른 압력분포 특성)

  • Lee, Chun-Ki;Kim, Hee-Sung;Moon, Serng-Bae
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.9
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    • pp.1106-1111
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    • 2014
  • This paper has a purpose to find out the characteristics of pressure distribution according to the POD shape installed in the Hydrofoil vessel, using the CFD. The results showed that as we cut the POD cross-section's basic shape along the x-axis from 0 to 8cm, the viscous resistance had decreased, but then the pressure resistance had increased modestly. However, the cutoff length of POD cross-section shape has close to 9cm, the viscous drag had increased and the pressure drag had decreased. As a result, we found out that the pressure resistance made more effects in POD shape than the viscous resistance, and the total resistance decreased near the 9cm of cutoff length.

The Inverse Design Technique of Propeller Blade Sections Using the Modified Garabedian-McFadden Method (Modified Garabedian-McFadden 방법을 이용한 프로펠러 날개 단면의 역설계 기법)

  • C.M. Jung;J.K. Cho;W.G. Park
    • Journal of the Society of Naval Architects of Korea
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    • v.36 no.4
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    • pp.28-36
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    • 1999
  • An efficient inverse design method based on the MGM(Modified Garabedian-McFadden) method has been developed. The 2-D Navier-Stokes equations are solved for obtaining the surface pressure distributions and coupled with the MGM method to perform the inverse design. The MGM method is a residual-correction technique, in which the residuals are the difference between the desired and the computed pressure distribution. The developed code was applied to several airfoil shapes and the propeller. It has been found that they are well converged to their targeting shapes.

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An Experimental Study of Supersonic Underexpanded Jet Impinging on a Perpendicular Flat Plate (평판 위에 충돌하는 초음속 과소팽창 제트에 관한 실험적 연구)

  • 이택상;신완순;이정민;박종호;김윤곤
    • Journal of the Korean Society of Propulsion Engineers
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    • v.3 no.3
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    • pp.53-61
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    • 1999
  • Impinging jets are observed when exhaust gases from missiles or V/STOL aircrafts impinge on the ground, flame deflector, ship deck, etc. The flow shows different patterns according to the nozzle geometry, nozzle-to-plate distance, and plate angle, for example. This paper describes experimental works on the phenomena (pressure distribution, occurrence of stagnation bubble, and so on.) when underexpanded supersonic jets impinge on a perpendicular flat plate using a supersonic cold-flow system, and compares the results with those obtained using a shock tunnel. The flow characteristics for the supersonic cold-flow system were also investigated. Surface pressure distribution of supersonic cold-flow system differed from that of shock tunnel because of water and temperature in the low-pressure chamber. Surface pressure distribution as to underexpanded ratio showed similar patterns together.

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