• Title/Summary/Keyword: Void Distribution

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A Numerical Study on the Two-Phase Natural Circulation Flow in Reactor Cavity under External Vessel Cooling (원자로 외벽냉각시 원자로공동에서의 자연순환 이상유동에 대한 수치적 연구)

  • Kim, Hong-Min;Seo, Jun-Woo;Kim, Kwang-Yong;Park, Rae-Joon;Ha, Kwang-Soon;Kim, Sang-Baik
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.781-785
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    • 2003
  • This work presents a numerical analysis of two-phase natural circulation flow in reactor cavity under external vessel cooling. Steady, incompressible, three-dimensional Reynolds-averaged Navier-Stokes equations for multiphase flows with zero equation turbulence model are solved to predict the shear key effect on the circulation rate of cooling water and the distribution of void fraction according to the different mass flow of inlet air. Results show that shear key has a positive effect on the circulation rate of cooling water and induce a local increase of void fraction below the shear key, but not remarkably.

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Effect of Electrical Properties in the insulating Varnish due to Internal Voids (내부 보이드가 절연 바니시의 전기적 특성에 미치는 영향)

  • Park, Hyoung-Jun;Heo, Youn;Kim, Weon-Jong;Yoon, Hun-Ju;Shin, Jong-Yeal;Hong, Jin-Woong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07a
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    • pp.472-475
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    • 2003
  • In this paper, insulating varnish has been used for field magnet and armature impregnated insulating material of electric locomotive and traction motor. When it was duplicated coating, it could be accuse internal void, and which could change electrical characteristics. We used to boundary elemental method of simulation tool, and improved optimal insulating design of insulating varnish according to measuring electric distribution in void of specimen.

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Fabrication of a rotating analyzer type spectroscopic ellipsometer and characterization of fluoride thin films (회전검광자형 분광타원해석기의 제작및 불화박막의 분석)

  • 김상열
    • Korean Journal of Optics and Photonics
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    • v.3 no.2
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    • pp.92-100
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    • 1992
  • A Spectroscopic Ellipsorneter(SE) is fabricated. The PSA configuration of the rotating analyzer type where the effects of the imperfect optical elements can be minimized is adopted. The straight through operation shows that the standard deviations of tan$\psi$ and cos$\Delta$ are less than 0.2% in the spectral range of 300nm-850nm. From the film data of ellipsometric spectra the bulk dispersion relation of a few fluorides and the void distribution inside the fluoride thin films are obtained.

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Analysis of PD Distribution Pattern according to the Arrangement of Void (보이드 배치에 따른 부분방전 패턴 분석)

  • Jeong, Byoung-Sun;Park, Dae-Hee;Cho, Kyu-Bok
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.2402-2404
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    • 1999
  • In this study, we measured the PD pattern with multiple voids in PET film. The analysis of PD pattern was employed the statistical factor such like CCF(cross correlation factor), asymmetry, kurtosis and etc. The difference of PD patterns caused by arrangement of voids, even if the same size and numbers of void in PET film. Such result of experiment will be used to know the PD source in the real equipment about arrangement and numbers of the defect in insulator.

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Analyses on Consolidation Characteristics of Dredged and Reclaimed Soils in Busan Area (부산지역 준설매립지반의 압밀거동 특성 분석)

  • Yoo, Nam-Jae;Kim, Dong-Gun;Hwang, Hee-Seok
    • Journal of Industrial Technology
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    • v.32 no.A
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    • pp.87-94
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    • 2012
  • For soils with high void ratios, the inverse method of utilizing results obtained from centrifuge model test was used to find the constitutive relation of effective stress - void ratio - permeability whereas conventional oedometer test and constant rate of strain consolidation(CRS) test about settlement of interface and pore pressure and distribution with time were compared with numerically estimated values to confirm such a constitutive relation as obtained from the inverse method. As results of numerical method, the volumetric ratio and reclamation velocity were obtained for the reclamation condition.

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Physical Characteristics of Soft Clay Improved by PFA Stabilization Agent (제지회계 지반개량재로 처리된 연약점토의 물리적 특성)

  • 김광빈;이용안;김유성
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.10a
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    • pp.561-568
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    • 2002
  • PFA(Paper Fly Ash) are reclaimed mainly or used in cement industry field as mixture agent in terms of materials recycling. Recently, research for recycling PFA as embankment materials or soil stabilization agent are undergoing in geotechnical engineering field. In this study, physical characteristics of PFA stabilization agent-soil admixtures are examined in change of water content, void ratio, consistency, grain distribution, specific gravity and density. Futhermore, the physical characteristics are compared with unconfined strength as engineering characteristics. Test results showed that unconfined strength and density are increased with increasing of PFA stabilization agent mixed ratio. On the other hand, specific gravity, void ratio and water content are decreased with increasing of PFA stabilization agent mixed ratio. It would be concluded that natural high water content ratio weak soil could be highly improved engineering and physical characteristics with PFA stabilization agent

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Development of an Optimum Void Detection Chart using Heat Transfer Simulation (열전달 시뮬레이션을 통한 최적공극탐지 차트개발)

  • Choi, Hyun-Ho;Park, Jin-Hyung;Ji, Goang-Seup
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.241-244
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    • 2006
  • It is essential to develop a large capacity, non-contact nondestructive inspection system having high reliability to investigate repaired and strengthened structures. Nowadays, an infrared camera is widely used in non-contact nondestructive inspection system. Because an infrared camera is sensitive to the surrounding environment, it is necessary to improve a sensitivity of thermal image information and a relationship between defects and thermal image information. In this papaer, presented is an optimum void detection chart for the optimum conditions to detect infrared rays from inside and outside defects like voids and cracks in concrete structures using extensive computer simulation. Sensitivity studies are performed with respect to variables influencing the temperature distribution such as heating temperature, heating time, and geometries of defect, etc. It may be stated that it could be successfully utilized for the non-contact nondestructive inspection system to detect defects in concrete structures.

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The Partial Discharge Properties of Oxidized Polyethylene (산화된풀리에틸렌의 부분방전 특성)

  • 이현수;한상옥
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.41 no.7
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    • pp.802-808
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    • 1992
  • To investigate degradation procedure and life time of the oxidized PE and the unoxidized PE, alternative voltage is applied to the CIGRE Method-II (CM-II) electrode system, which is loaded artificial void, and measures the distribution of partial discharging generation. From the results, the samples etched by oxidation had wide degradation area of dielectric strength. Furthermore, discharge starting voltage was shifted to low voltage, the discharge generation frequency was high and consequently, the quantity of mean charge becomes small. Also, life time of the oxdized sample is shortened according as the oxidation time is longer.

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The Influence of Distribution Characteristics of Compression Index on the Spatial Distribution of Consolidation Settlements (압축지수분포 특성이 압밀침하량 분포에 미치는 영향)

  • Kim, Dong-Hee;Kim, Min-Tae;Kim, Kyu-Sun;Lee, Woo-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09b
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    • pp.76-80
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    • 2010
  • This paper describes that estimation methods for the distribution of consolidation settlements to investigate the influence of distribution characteristics of compression index on the spatial distribution of consolidation settlements. When the variation of compression index is considerable, the spatial distribution of compression index is estimated using ordinary cokriging. The spatial distribution of consolidation settlements estimated by considering both the variation of compression index and void ratio (CASE-1) is different from the conventional mean value of all soil properties (CASE-2). The settlement of CASE-1 shows the larger variation at short distances rather than that of CASE-2. Whereas the spatial settlement distribution of CASE-1 is affected by the spatial distribution of compression index and the thickness of consolidation layer, the distribution of CASE-2 is significantly influenced by the distribution of the thickness of consolidation layer.

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Analysis of Air Voids System Using Image Analysis Technique in Hardened Concrete (화상분석법을 통한 경화 콘크리트의 미세 공극 구조 분석)

  • Yun Kyong-Ku;Jeong Won-Kyong;Jun In-Koo;Lee Bong-Hak
    • Journal of the Korea Concrete Institute
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    • v.16 no.6 s.84
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    • pp.741-750
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    • 2004
  • Air voids in hardened concrete have an important influence on concrete durability such as freeze-thaw resistance, surface scaling resistance, and water permeability, and they have been characterized by spacing factor Linear traverse and point count methods in ASTM standard have been used in estimating an air void system in hardened concrete. However, these methods require lots of time and efforts, further they are not repeatable. Image analysis method could be utilized In estimating an air void systems in hardened concrete with a developments of microscope, digital camera and computer program. The purpose of this study was to develope image analysis method and provide a guideline by comparing the results from ASTM method and image analysis method. The concerns were at air void content and diameter distribution, air voids system as well as spacing factors. The experimental variables included air content by air entrained agent (0, 0.01, $0.03\%$) and depth of specimen (top, middle, bottom). The result showed that it was possible to calculate spacing factor using image analysis technique, as well as air content, air diameter distribution, and air structure. This study also contributed in developing an reasonable and repeatable image analysis method.