• Title/Summary/Keyword: internal circulation

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A Study of the Use of Online Public Access Catalogs (온라인목록(Online Public Access Catalog : OPAC) 이용의 편이도에 관한 연구)

  • Ro Moon Ja
    • Journal of the Korean Society for Library and Information Science
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    • v.19
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    • pp.151-188
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    • 1990
  • The aims of automation efforts in libraries are the rationalization of interval work and improvement of user services. After a period of exclusive internal computer utilization, later voluntary contact with the computer (e.g., circulation control with self services), patrons of American libraries now have to go to a computer terminal if they want certain information. Online public access catalogs(OPAC) have been used in American libraries since the end of the seventies. But OP AC are accepted by patron only if they have a useful and flexible user interface. This paper briefly describes the use of online catalogs in different type of libraries, categories of user (user, non-user), aspect of catalog use in context with computer experience etc. The disscussion then focuses on the characteristics of the final report of online catalog use study of Council on Library Resources and user problems in searching, as reported in many other catalog use studies.

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A new correlation of the enthalpy of vaporization for pure refrigerants (순수물질 냉매에 대한 증발엔탈피의 새로운 상관식)

  • 박경근
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.10 no.4
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    • pp.449-455
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    • 1998
  • A header' is the device that makes uniform flow distribution in all branches from header of heat exchangers, pipe burner or chemical equipments. In this study, experimental tests have been performed in order to investigate the flow distribution characteristics in a straight header and tapered header which have 6 and 11 glass pipe branches. The experimental equipment consists of a water circulation system where the fluid velocity in each glass pipe is measured by Ar-ion LDV system. From the experiments and the theoretical equation, it could be recommended that tapered header should be determined so that its internal velocities inside the header become uniform according to taper of the header and number of attached branches for uniform flow distribution in energy systems.

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Cryogenic Systems for HTS Power Cables

  • Yeom, Han-Kil;Koh, Deuk-Yong;Lee, Bong-Kyu;Kim, Ig-Seang
    • Progress in Superconductivity and Cryogenics
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    • v.5 no.1
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    • pp.133-135
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    • 2003
  • Cryogenic systems are requirement for the operation of HTS power cables. In general, HTS power cables require temperature below 77K, a temperature that can be achieved from the liquid nitrogen at latm or sub-cooled LN2 above latm. HTS power cable needs sufficient refrigeration to overcome its low temperature heat loading. This loading typically cones in two forms : (1) heat leaks from the surroundings and (2) internal heat generation. This paper explains the cooling test system of 10m HTS power cable. This system is composed of storage dewar, auto fill system, core cryostat and cold-box. Storage dewar is a LN2 storage tank and auto fill system is a LN2 supply device to the sub-cooler, Core cryostat is a LN2 flow line. Cold box is a control unit of temperature and flow rate. It is composed of control valve, flow meter, sub-cooler and circulation pump, etc..

A Numerical Study on Interaction and Combustion of Droplets Injected into a Combustor (연소실에 분사된 액적 간의 상호작용과 연소현상에 대한 수치적 연구)

  • Kook, J.J.;Park, S.H.
    • Journal of the Korean Society of Combustion
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    • v.4 no.1
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    • pp.17-26
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    • 1999
  • Vaporization, ignition and combustion of fuel droplets in tandem array are theoretically investigated to understand the droplet interactions in combustors. Including the effects of density variation in gas-phase, internal circulation and transient liquid heating, a numerical studies are performed by changing parameters such as initial droplet temperatures, initial droplet spacings, initial Reynolds numbers, surrounding gas temperatures, and activation energies of fuel vapors. Combustion regime maps classify the droplet combustion phenomena according to the configuration and location of the flame with respect to injection Reynolds numbers and surrounding gas temperatures. In addition, it is shown that the dynamic histories of droplets and ignition delay times are dependent on droplet size ratios and initial spacings of tandem droplets.

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Analysis of Flow Field around Multiple Fluid Spheres in the Low Knudsen Number Region (저 누드센 영역에서 다중 유체구 주위의 유동장 해석)

  • 정창훈;이규원
    • Journal of Korean Society for Atmospheric Environment
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    • v.19 no.6
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    • pp.733-743
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    • 2003
  • The flow field in multiple fluid sphere systems was studied analytically. The expanded zero vorticity cell model based on Kuwabara's theory (1959) was applied and the effects of gas slippage at the collecting surface were considered. Also, the solid sphere system was extended to fluid sphere including the effects of the induced internal circulation inside the liquid droplet spheres or gas bubble systems. As a result, the obtained analytic solution was converged to the existing solutions for flow field around solid and bubble sphere systems with proper boundary conditions. Based on the resolved flow field, the terminal velocity around the collecting fluid spheres was obtained. Subsequently, this study evaluated the most general solution for flow field around the multiple fluid sphere systems. The obtained flow field in multiple fluid sphere could be used as a fundamental consideration of wet scrubber design and devices for removing particles by fluid-fluid interactions.

False aneurysm of right common carotid artery due to gun shot wound: report of a case (총창으로 인한 우측 총경동맥의 가성 동맥류 치험 1)

  • 남구현
    • Journal of Chest Surgery
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    • v.17 no.3
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    • pp.488-491
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    • 1984
  • Vascular injuries from gun shot wound is rare in these days, in Korea. A Case of false aneurysm of the right common carotid artery due to penetrating injury to the neck by carbine. The confirmatory diagnosis was made by right carotid angiogram which revealed bean-sized aneurysmal sac at the mid-portion of the right common carotid artery. Despite of no symptoms, emergency false aneurysmectomy and reconstruction with on-lay vein patch graft using left greater saphenous vein for threat of rupture and embolization from mural thrombi. During repair of common carotid artery, cerebral circulation was maintained with internal shunt. The postoperative course was uneventful except limit of motion of right upper extremity due to initial injury.

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Moyamoya Biomarkers

  • Smith, Edward R.
    • Journal of Korean Neurosurgical Society
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    • v.57 no.6
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    • pp.415-421
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    • 2015
  • Moyamoya disease (MMD) is an arteriopathy of the intracranial circulation predominantly affecting the branches of the internal carotid arteries. Heterogeneity in presentation, progression and response to therapy has prompted intense study to improve the diagnosis and prognosis of this disease. Recent progress in the development of moyamoya-related biomarkers has stimulated marked interest in this field. Biomarkers can be defined as biologically derived agents-such as specific molecules or unique patterns on imaging-that can identify the presence of disease or help to predict its course. This article reviews the current categories of biomarkers relevant to MMD-including proteins, cells and genes-along with potential limitations and applications for their use.

Experimental study on flow distribution in manifolds by a tapered header (경사 분배관에 의한 다지관내의 유속분포에 대한 실험적 연구)

  • 윤영환;이상헌
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.10 no.1
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    • pp.1-10
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    • 1998
  • A header is the device that makes uniform flow distribution in all branches from header of heat exchangers, pipe burner or chemical equipments. In this study, experimental tests have been performed in order to investigate the flow distribution characteristics in a straight header and tapered header which have 6 and 11 glass pipe branches. The experimental equipment consists of a water circulation system where the fluid velocity in each glass pipe is measured by Ar-ion LDV system. From the experiments and the theoretical equation, it could be recommended that tapered header should be determined so that its internal velocities inside the header become uniform according to taper of the header and number of attached branches for uniform flow distribution in energy systems.

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Blood Conservation in Coronary Artery Bypass Surgery - in 24 consecutive patients - (관상동맥 우회로술 환자에서 혈액 보존법)

  • 최종범
    • Journal of Chest Surgery
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    • v.25 no.10
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    • pp.1048-1054
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    • 1992
  • With use of a simple, inexpensive and nonpharmacological program for blood conservation, 24 consecutive patients underwent elective or urgent coronary artery bypass grafting without need of homologous red cell transfusions and /or fresh frozen plasma transfusions in 16 patients[66.7%]. Left internal mammary artery graftings were done in 18 patients[75%], with supplemental saphenous vein grafts in all. Intraoperatively, autologous heparinized blood was removed before bypass and retransfused at the conclusion of ext-racorporeal circulation. The volume remaining in the oxygenator and tubing set was returned without cell processing or hemofiltration. Using the hard-shell cardiotomy reservoir from the oxygenator, autotransfusion of the shed mediastinal blood was continued hourly by the next early;norning. The mean postoperative mediastinal blood loss was 364$\pm$234ml, whereas 553$\pm$383ml was autotransfused. 4 patients [16.7%] received homologous blood and an additional 4 patients[16.7%] fresh frozen plasma. Thus, in total, 16 patients[66.7%] were not exposed to any homologous blood products during the hospital stay. At discharge, the mean hemoglobin concentration was 10.3$\pm$1.6g /dl. Postoperative complications were few and there was no hospital death.

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Analysis on Pressure and Temperature wave of Self Oscillating Heat Pipe (자려 진동 히트파이프의 압력 및 온도 파형 해석)

  • Choi, J.H.;Yoon, D.H.;Oh, C.;Kim, M.H.;Yoon, S.H.
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2000.11a
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    • pp.43-49
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    • 2000
  • Heat transfer characteristics of self oscillating heat pipe were experimentally investigated for the effect of fill charge ratios and heat loads. The heat pipe used for this study is made of copper capillary, has 0.002m internal diameter, a 0.34m length in one turn and consists of 19 turns. Heating and cooling section each have a length of 70mm. Water was used as working fluid inside heat pipe. As the experimental results, the self oscillating heat pipe was operated by self-exited oscillation and circulation of working fluid and the oscillation within the self oscillating heat pipe assumed chaotic behavior.

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