• Title, Summary, Keyword: 입구 부

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Scattering of Obliquely Incident Waves by a Semi-infinite Breakwater or a Breakwater Gap of Partial Reflection (부분 반사 반무한 방파제 또는 방파제 개구부에 사각으로 입사하는 파의 산란)

  • Kim, Han-Na;Suh, Kyung-Duck
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.21 no.4
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    • pp.334-344
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    • 2009
  • In the present paper, analytic solutions are derived for scattering of obliquely incident waves by a semi-infinite breakwater or a breakwater gap of partial reflection. In order to examine the appropriateness of the derived solutions, they are compared with the solutions derived by McIver in 1999 and Bowen and McIver in 2002 for a semi-infinite breakwater and a breakwater gap, respectively, in the case of perfect reflection. The derived analytic solutions are used to investigate the effect of reflection coefficient of the breakwater and wave incident angle upon the tranquility at harbor entrance. The tranquility is deteriorated by the reflected waves as the reflection coefficient increases and as the waves are incident more obliquely.

Transtibial Double Bundle PCL Reconstruction using TransFix Tibial Fixation - Technical Note - (TransFix 경골부 고정을 이용한 경 경골 두 다발 후방십자인대 재건술 - 수술 술기 -)

  • Lee, Yong-Seuk;Jung, Young-Bok;Ahn, Jin-Hwan;Kang, Bun-Jung;Shin, Yun-Chang;Kong, Chae-Gwan
    • Journal of the Korean Arthroscopy Society
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    • v.10 no.2
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    • pp.203-208
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    • 2006
  • Purpose: Previous transtibial double bundle posterior cruciate ligament (PCL) reconstruction methods have several problems in graft length and tibial fixation. We introduce new surgical method that is less restrictive by graft length and is more stable with single tibial fixation. Operative technique: After diagnostic arthroscopy, we prepare the graft, ream the tibial tunnel and perform the procedure for TransFix tibial fixation. Femoral 2 tunnel is made and graft is passed via anteromedial (AM) portal. Tibial fixation is done and femoral 2 graft is fixed sequentially at each knee position. Conclusion: TtransFix tibial single fixation method in double bundle PCL reconstruction provides more stable fixation, more free graft selection and prevents graft damage by passing the graft via AM portal.

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The Prediction of Air Flow and Pressure Loss at Inlet Duct (입구덕트 공기유량 및 압력손실 예측방법)

  • Lee, Bo-Hwa;Lee, Kyung-Jae;Yang, Soo-Seok
    • Journal of the Korean Society of Propulsion Engineers
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    • v.14 no.1
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    • pp.48-55
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    • 2010
  • The purpose of this paper was to address the methodology of the air flow measurement using duct mach number that was considered area-weighed average obtained by total, static pressure and temperature measured at engine inlet duct. Without installing boundary rake, the prediction of air flow measurement was discussed. Actual air flow measurement and pressure value using pressure loss through inlet seal were described to improve the reliability and operability of altitude engine test facility.

Analysis on Cooling Effects of the Vertical Type Geothermal Heat Pump System Installed in a Greenhouse for Raising Seedling (수직형 지열히트펌프 시스템의 육묘 온실 냉방 효과 분석)

  • Kang, Youn Ku;Ryou, Young Sun;Kim, Jong Goo;Kim, Young Hwa;Jang, Jae Kyoung
    • Journal of Bio-Environment Control
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    • v.22 no.1
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    • pp.19-25
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    • 2013
  • In this study, the cooling experiment was carried out in $1,650m^2$ area of the seedling greenhouse from June 6, 2011 to september 18, 2011 with the vertical type geothermal heat pump system of 350 kW scale (175 kW ${\times}$ 2 units) installed in the greenhouse, cooling effects were analyzed and we tried to find more effective operation methods of the geothermal heat pump system. In case of one unit heat pump (175 kW) operation, when evaporator inlet water temperature changed from $13.0^{\circ}C$ to $15.5^{\circ}C$, cooling COP of the system was in 1.1~1.8 range and in case of two unit heat pump (350 kW) operation, when evaporator inlet water temperature changed from 13.0 to 15.5, cooling COP of the system was in 2.0~2.7 range. The accumulated cooling heat quantity of June, July, August and September was 14,718.6, 26,765.1, 28,437.2 and 10,065.0 kWh, respectively.

황금알 낳은 동해 최북단 저도 도등

  • Kim, Jun-Gi;Jeon, Jae-Cheon;Hyeon, Yeong-Seop
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • pp.332-334
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    • 2013
  • 일반적인 도등은 통항이 곤란한 좁은 수로, 만 입구, 항구 등에서 선박을 안전한 항로로 유도하기 위하여 항로의 연장선상의 육지에 설치하여 2개의 등화를 수직선상에 보고 진입하게 하는 광파표지이다. 그러나 저도 도등은 위와 같은 기능이 아닌 군사지역인 저도어장 어선들의 안전한 조업을 할 수 있도록 해주는 지표가 된다. 본 발표에서 저도 도등의 구체적 역할과 그 효과에 대하여 논하고자 한다.

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Fluid-Structure Interaction in the Axisymmetric Abdominal Aortic Aneurysm By Pulsatile Flow (맥동유동에 의한 축대칭 복부대동맥류의 유체-고체 상호작용)

  • 권치호;김영호
    • Journal of Biomedical Engineering Research
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    • v.22 no.1
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    • pp.59-68
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    • 2001
  • 유체-고체 상호작용을 고려하여 다양한 복부대동맥류 모델에 대해서 맥동유동 및 구조를 동시에 해석하였다. 동맥류의 확장부 크기와 혈관벽 두께에 따라서 총 여덟 개의 축대칭 동맥류 모델을 선정하였다. 유한체적법 및 압력기반의 유한차분법을 이용하여 유동을 해석하였으며, 유한요소법을 이용하여 구조해석을 수행하였다. 동맥류의 확장부위가 클수록 최대응력은 최대확장부위와 변곡점에 해당하는 동맥류의 입구 및 출구 부분에 집중되었으며, Von Mises 응력은 최대확장부위 뿐만 아니라 동맥류의 근위부와 원위부($\pm$1D)에서도 현저하게 증가하였다. 또한 더욱 확장된 모델일수록 혈관벽은 직경방향의 변위보다 축방향의 변위가 지배적이었으며, 동맥류 원위부보다 근위부에서 큰 축방향 변위를 나타냈다. 동맥류 입구부의 미약한 와류는 한 주기동안 그 크기와 강도를 더해가며 동맥류 원외부로 이동하였고, 동맥류의 내부 유동은 압력차이가 감소하는 기간동안 더 큰 영향을 받았다. 확장정도가 심할수록 동맥류 내부에 더 크고 강한 와류가 관찰되었다. 압력차이가 최소가 된 직후 동맥류의 근위부와 원위부동맥 벽 근처에서의 역방향 유동이 관찰되었다. 대체로 혈관벽 두께가 감소한 모델과 더욱 확장된 모델일수록 벽전달률은 감소하였다. 혈관벽의 탄성에 의하여 압력차이와 벽전달률 사이에 위상차가 존재함이 확인되었다. 유체-고체의 상호작용을 고려한 연구는 다른 심혈관계를 이해하는데도 매우 유익할 것으로 생각된다.

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The High-speed train model for reducing the micro-pressure wave in railway tunnel (고속철도 터널에서의 미기압파 저감을 위한 모형실험)

  • Jang, Yong-Jun;Park, Won-Hee;Kim, Seung-Tae
    • Proceedings of the KSR Conference
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    • pp.1330-1336
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    • 2007
  • The purpose of the study was to verify deduction of each coefficient necessary to analysis on micro-pressure waves and reliability of the analysis result. The tunnel running train model testing device used in the test was manufactured by scale of 1:60 and the study used a train model with ten cars long according to specifications of KTX model. The study applied tunnels with cross sections of $107.9m^3\;and\;95.1m^3$ and applied tunnel extensions with 1km, 0.75km and 0.5km. Also, the study tested train speed by changing it into 275, 300, 325 and 350km/h. The test device was a hydraulic launch system composed of a train model, a hydraulic launcher, a tunnel model and a brake. The study measured speed of a model trainby a speed sensor installed in the point of each 1.2m from the front of tunnel entrance and a pithead of tunnel exit and measured pressure change of internal tunnel continuously by installing pressure sensors in the entrance part of tunnel, in the middle part of tunnel and in the exit part of tunnel. As the result of the measurement, it was known that pressure slope of pressure wave happened in the entrance part of tunnel was increased by a nonlinear effect while spreading the tunnel or its pressure slope was reduced by diffusion. Also, the study compared and analyzed micro-pressure waves happened in the exit part of the tunnel by installing each kind of hoods in the entrance part of the tunnel to prevent reduction of micro-pressure waves.

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Study on Effect of Increase in Inlet Temperature on Nafion Membrane Humidifier (입구온도 변화가 중공사형 나피온 막가습기의 성능에 미치는 영향에 대한 연구)

  • Hwang, Jun-Young;Chang, Hyo-Sun;Kang, Kyung-Tae;Kang, Heui-Seok
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.4
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    • pp.361-369
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    • 2011
  • The effect of an increase in the temperature of inlet air on the performance of a membrane humidifier for a PEMFC (Polymer Electrolyte Membrane Fuel Cell) vehicle was investigated both experimentally and numerically. A shell-and-tube type gas-to-gas humidifier with Nafion membrane was tested. The experimental result showed that water transfer varies nonlinearly with the temperature elevation. Numerical analysis based on detailed modeling was also conducted in simplified geometry of a single tube to explain this nonlinear behavior. The simulation revealed that the local water flux varies nonlinearly and dramatically along the tube. The analysis was based on the inverse relationship between the increase in temperature and decrease in relative humidity, both of which seriously affect the water conductivity of the membrane.

A Study on Numerical Calculations of Multi-stage Dedust System coupled with the Collection Principle of Cyclone, Inertial Impaction and Bag filter (I) : Optimized Design of Dedust inlet (사이클론과 관성충돌 및 백필터의 제진원리를 일체화한 멀티 제진시스템의 수치 해석적 연구 (I) : 집진기 입구 최적화 설계)

  • Jung, Yu-Jin;Jeong, Moon-Heon;Park, Ki-Woo;Hong, Sung-Gil;Lim, Ki-Hyuk;Suh, Hye-Min;Shon, Byung-Hyun
    • Proceedings of the KAIS Fall Conference
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    • pp.367-370
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    • 2012
  • 본 연구는 하나의 장치 내에서 "싸이클론-관성충돌-여과포 집진"이라는 다단 제진 단계가 동시에 이루어져 입경 분포별로 순차적인 제진이 가능한 멀티 집진기의 처리가스 제어 효율을 극대화시킬 수 있는 기류 흐름을 얻기 위한 최적화 설계 조건을 검토하는 것이다. 우선 1단계 제진 과정인 원심력을 이용하여 조대입자의 유선 이탈을 촉진시킬 수 있는 사이클론 유동을 최적화시키기 위한 집진기 입구 형상 설계 검토를 위해 수치 해석적 연구를 수행하였다. 그 결과, 멀티집진기 입구 형상을 일반적인 설계 방식인 접선 유입식으로만 설계한 것에 비해 선회류를 한번 더 가속화시킬 수 있는 가이드 베인을 추가로 설계한 경우 선회류의 pitch가 짧고 강하게 형성되어 사이클론부에서 조대입자의 유선 이탈을 촉진시키는데 매우 효과적인 것으로 예측되었다. 단, 사이클론부 하단 벤츄리 형상으로 인해 약 4~5 m/s의 강한 하향 흐름이 호퍼 하단까지 형성되고 있어 탈리 분진의 재비산 문제가 발생할 가능성이 크므로 벤츄리 형상 설치 유무에 대한 영향도 추가적으로 연구가 필요할 것으로 판단된다.

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