• Title/Summary/Keyword: Opening Pressure

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A Micro Shunt Valve with Anti-siphon Effect

  • Lee, Sang-Wook;Yoon, Hyeun-Joong;Yang, Sang-Sik
    • KIEE International Transactions on Electrophysics and Applications
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    • v.4C no.1
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    • pp.31-34
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    • 2004
  • This paper presents the fabrication and testing of a two-way pressure regulation micro shunt valve with an anti-siphon effect that can be implanted in hydrocephalus patients. This micro shunt valve consists of a silicone rubber membrane and a valve seat for the opening pressure control as well as the anti-siphon behavior. The two-way pressure regulation and the anti-siphon effect of the micro shunt valve are verified experimentally for various sizes of membranes and valve seats.

Study on Static Characteristics of Hybrid Spool Valve (하이브리드 스폴밸브의 정특성 연구)

  • Yun, So-Nam;Ham, Young-Bok;Kim, Dong-Su
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.121-126
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    • 2001
  • In this study, the 4-way spool valve characteristics are clearly defined and proposed new type of spool valve. This paper presents governing equations of the flow through clearances between sleeve and spool as a model of orifice flow for null characteristic analysis, and programmed analysis software of it. This software is possible to basically analysis that not only which case of open center, closed center or critical center but +,- displacement of spool, lab position, boundary region and spool opening of the valve, and to estimate the pressure variation in the spool and external leak flow variation. We are convinced that the scale of load pressure difference is changed as lab condition of spool valve, and this scale is changed with boundary point on the annular clearance. It is vary useful to designer and user of spool valve with this design data and analysis software.

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Elastic-plastic Fracture Mechanics Analyses for Burst Pressure Prediction of Through-wall Cracked Tubes (관통균열 세관의 파열압력 예측을 위한 탄소성 파괴역학 해석)

  • Chang Yoon-Suk;Moon Seong-In;Kim Young-Jin;Hwang Seong-Sik;Kim Joung-Soo;Kim Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.10 s.241
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    • pp.1361-1368
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    • 2005
  • The structural and leakage integrity of steam generator tubes should be sustained all postulated loads with appropriate margin even if a crack is present. During the past three decades, for effective integrity evaluation, several limit load solutions have been used world-widely. However, to predict accurately load carrying capacities of specific components under different conditions, the solutions have to be modified by using lots of experimental data. The purpose of this paper is to propose a new burst pressure estimation scheme based on fracture mechanics analyses for steam generator tube with an axial or circumferential through-wall crack. A series of three dimensional elastic-plastic finite element analyses were carried out and, then, closed-form estimation equations with respect to both J-integral and crack opening displacement were derived through reference stress method. The developed engineering equations were utilized for structural integrity evaluation and the resulting data were compared to the corresponding ones fiom experiments as well as limit load solutions. Thereafter, since the effectiveness was proven by promising results, it is believed that the proposed estimation scheme can be used as an efficient tool for integrity evaluation of cracked steam generator tubes.

An Analysis of Mechanism of Auto-Sensing Breaker's Automatic Impact (지능형 브레이커의 자동타격 메카니즘 분석)

  • Park, Sung-Su;Noh, Dae-Kyung;Lee, Dae-Hee;Lee, Geun-Ho;Kang, Young-Ky;Cho, Jae-Sang;Jang, Joo-sup
    • Journal of the Korea Society for Simulation
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    • v.25 no.4
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    • pp.31-42
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    • 2016
  • This study aims to identify the core technology for the automatic impact of the auto-sensing breaker that is one of the construction machinery which do not have a notable development success case yet in Korea. The study has been carried out as follows. Firstly, an analysis model was developed after determining the interconnection of pressure receiving area, opening area and port. And then, a simulation of situation that hard rock and soft rock are mixed was carried out to verify if it is possible to switch between long impact mode and short impact mode continuously. Lastly, the dynamic behavior of automatic control valve induced by the change of impact mode was analyzed based on the analysis result to decipher the core principle of automatic impact control.

A Study On Effectiveness of Prevent Smoke Backflow in Apartment (계단식 공동주택 방연풍속 실효성에 대한 연구)

  • Lee, Kwang­Soo;Yoon, Myong­O;Lee, Jun
    • Journal of the Society of Disaster Information
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    • v.17 no.1
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    • pp.1-9
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    • 2021
  • Purpose: The purpose of this study is to analyze the differential pressure and velocity to prevent smoke backflow of Stairways Apartment House fire, and verified the effectiveness of smoke velocity standards proposed by NFSC 501A. Method: The smoke control design of the stairways apartment house of the real model and the performance of the velocity to prevent smoke backflow according to the window opening conditions of the living room were analyzed using the CONTAM program. Result: Although the differential pressure performance of the apartment's smoke control system was satisfactory, it was found that Performance of velocity to prevent smoke backflow did not come out according to the opening condition of the living room window. Conclusion: In the case of Stairways Apartment House, it is necessary to review the method of making exceptions to the 'velocity to prevent smoke backflow' standard required by the National Fire Safety Codes(NFSC 501A)

A proposal and evaluation of a revised GIN method (수정 GIN 기법의 제안 및 검증)

  • Sagong, Myung;Park, Youngjin
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.23 no.3
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    • pp.151-165
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    • 2021
  • Grouting, which is applied for the increase of ground strength and the decrease of permeability, is complex process because of several reasons, so the process needs to be elaborated. Injection process in consideration of ground condition and optimization of grouting sequence is essential. In this study, GIN (Grouting Intensity Number), multiple of injected grout volume and pressure, is revised to consider injection pressure reduction and joint opening during grouting process. A revised GIN process is evaluated through a field test. A revised GIN, considering ground condition, injection pressure, follows GIN envelope and produces rational grouting process. The result of a revised GIN reduces permeability of the ground in the order of 10-1~10-2 cm/sec.

Improvement of In-Situ Stress Measurements by Hydraulic Fracturing - Focusing on the New Standard by Japanese Geotechnical Society (수압파쇄를 이용한 초기응력 측정 결과의 신뢰도 제고 방안 - 일본 지반공학회 표준시험법 개정안을 중심으로)

  • Kim, Hyung-Mok;Lee, Hangbok;Park, Chan;Park, Eui-Seob
    • Tunnel and Underground Space
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    • v.32 no.1
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    • pp.1-19
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    • 2022
  • In this report, new standard, published by Japanese Geotechnical Society, on in-situ stress measurements by hydraulic fracturing was reviewed. In the standard, modification was made for the calculation of fracture re-opening pressure in consideration of fracture surface roughness and residual aperture. The standard also presents how much the system compliance influences the estimation of the fracture re-opening pressure and subsequent in-situ stresses. It is shown that the stiffer the rock mass is, the system compliance should be sufficiently small enough so as to obtain in-situ stress measurement with higher confidence.

Characteristics of Flow Induced Noise from a Ball Valve Used for a Gas Pipeline Using an Acoustic Camera (음향 카메라를 이용한 가스 파이프라인 볼밸브 유동소음 특성)

  • KIM, CHUL-KYU;LEE, SANG-MOON;JANG, CHOON-MAN
    • Journal of Hydrogen and New Energy
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    • v.28 no.1
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    • pp.106-112
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    • 2017
  • The present study describes flow induced noise generated from a ball valve used for a gas pipeline. Noise generation from a ball valve mainly induces by interference between unstable(or fluctuating) leakage flow and pipe wall when the ball valve is working closed or opened. To measure the positions of the noise source and the amplitude of noise with respect to measuring frequencies, a commercial acoustic camera is introduced. Noise characteristics generated by the ball valve have been performed by four valve opening rates: 30, 50, 70 and 100 percents. It is noted that 100 percent opening rate means that the valve is fully opened. Throughout the experimental measurements using the acoustic camera, the location of the noise source and the noise amplitude with respect to the frequencies for the test ball valve are clearly evaluated. It is found that the dominant frequencies come from the fluctuating flow at the downstream of the ball valve for four opening rates are observed between 3,000Hz and 3,200Hz. Maximum noise amplitude comes from the ball valve reaches 75dB at the valve opening rate of 50 percent.

A Study on the History of Korea's Modern Library - with Special Reference to the Establishment of Modern Libraries and its Characteristics in the Opening Period. - (근대한국도서관사 연구 - 개화기의 근대도서관 성립과 그 성격을 중심으로 -)

  • Lee Choon-Hee
    • Journal of the Korean Society for Library and Information Science
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    • v.29
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    • pp.11-44
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    • 1995
  • The purpose of this study is to investigate the general characteristics of modem library which was in a germinal stage at the opening period of Korea. The major findings of this study is summarized as follows. 1. Modern libraries which began to develop during the opening period of Korea were deeply rooted in the spirit of patriotism. After 1905, which was the year of so-called Korean-Japanese Protocal concluded under the Japanese military pressure, the patriotic enlightenment campaign against foreign penetration developed rapidly throughout the country. Accordingly, the movement for establishing modern library was carried out among advanced reformers. 2. The first modern school library was built in the private school of Wonan established by the residents of Wonsan area. They believed that the best way to strengthen the national power to oppose Japanese penetration was to learn the Western culture and technology. 3. The first modern public library named The Central Library of Korea was originated by Oh Ha Young and his comrade in 1906. Included among these promoters of the library were Yun Chi Ho and Min Sang Ho, two persons who had experienced Western culture during their study abroad. 4. Pakmunkuk, the newspaper office of the government, had its own library in 1883 which was the first modernized special library in Korea. 5. Major factors which hindered the rapid growth modern libraries m the opening period are as follows; (1) Lack of people's demand fer the library. (2) Limited scope of the publications(mainly school text-books) (3) Poor financial conditions. 6. Japanese invasion in 1910 had broken the growing roots of modern libraries in formative stage.

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A Study on the Enhance of Air tightness Performance of a New Type Silding Window with horizontally Rolling Wheels (수평 구름 바퀴가 적용된 신 유형 미서기 창문의 기밀성능 개선에 관한 연구)

  • Jang, Hyok-Soo;Kim, Young-Il;Chuung, Kwang-Seop
    • Journal of Energy Engineering
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    • v.24 no.4
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    • pp.63-70
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    • 2015
  • Crevices between window and window frame cause not only heat losses but also serve path to sound transmission and infiltration of fine dusts that are harmful to humans. There were many efforts in the past to eliminate these crevices but because of the windows' indispensable function of opening and closing, it was an unsolvable problem. In this study, a new type sliding window is developed by applying horizontally rolling wheels to implement a surface sealing which is excellent for enhancing air tightness. To evaluate the feasibility of the newly developed window, forces for opening and closing, durability and air tightness were testet according to Korean Testing Standards. Force for opening a 2000 N window is 30 N. It endured 100,000 cycles of opening and closing. Infiltration was $0.00m^3/(m^2h)$ for a pressure difference of 10 Pa. Since this window has few moving parts, it has favorable features of low cost and few breakdown.