• Title/Summary/Keyword: direct test

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CFD Analysis for Thermal Mixing in a Subcooled Water during Steam Jet Discharge (증기제트 방출시 과냉각수조 내의 열혼합 현상 CFD 해석)

  • Kang, Hyung-Seok;Song, Chul-Hwa
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.513-514
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    • 2006
  • A CFD analysis for a thermal mixing experiment during steam jet discharge was performed to develop the analysis methodology for the thermal mixing between steam and subcooled water and to find the optimized numerical method. In the CFD analysis, the steam condensation phenomena by a direct contact was modelled by the so-called condensation region model. The comparison of the CFD results with the test data showed a good agreement as a whole, but a small temperature difference was locally found at some locations. However, the commercial CFD code of CFX4.4 together with the condensation region model can simulate the thermal mixing behaviour reasonably well when a sufficient number of mesh distribution and a proper numerical method are adopted

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Calculation of the Crack Length for a Pipe Specimen using the Modified Load Ratio Method (수정된 하중비법을 이용한 배관 시험편의 균열 길이 계산)

  • Choi, Jung-Hun;Huh, Yong;Koo, Jae-Mean;Seok, Chang-Sung;Park, Jae-Sil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.12
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    • pp.1375-1382
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    • 2009
  • The objective of this paper is to apply the load ratio method to the measurement of the crack length of the real scale pipe specimen. The load ratio method was modified and finite element analyses were performed to derive the relationship between the normalized compliance and the normalized crack length for the pipe specimen. In order to measure the crack length, the direct current potential drop method and the modified load ratio method were applied to the pipe test. The applicability of the modified load ratio method was confirmed by comparing the calculated crack length with the measured crack length from the pipe experiment.

Design and Performance Test of the Force Motor for Direct Drive-type Pneumatic Servo Valve (직동식 공압서보밸브의 Force Motor 설계 및 성능시험)

  • 이원희;김동수;박상운
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.836-839
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    • 2003
  • A pneumatic servo valve which is widely applied in industrial field. And It is consist of force motor, spool & sleeve and servo controller. In this study. we developed the force motor which is consume to low power for a pneumatic servo valve. We could reduce the number of turn of the solenoid by using ferromagnetic permanent magnet and took different direction of each other using one coil instead of two coil. we modeled a system consisting of various electro-mechanical subsystems. The appropriateness of the model was verified by simulation. The simulation model resolved the motion of spool, the winding current and the magnetic force. Also, we calculated the displacement and velocity of the spool, flux contour line, b vector. flux density. flux linkage, back EMF etc.

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Influence of Family and Work Experience on Occupational Aspirations of Adolescents: A Path Model (가족배경변인과 시간제취업경험이 청소년의 직업소망에 미치는 영향: 경로분석을 중심으로)

  • Ok, Kyung Hee
    • Korean Journal of Child Studies
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    • v.14 no.2
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    • pp.149-168
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    • 1993
  • The purpose of this study was to develop a theoretical model from which to test the influence of family background and work experience on the level of rural high school students' (N=381) occupational aspirations. In the basic model, mother's occupation directly influenced occupational aspirations. Father's education influenced occupational aspirations directly and also indirectly through students' academic achievement. The number of working hours per week had a direct and negative influence on academic achievement. In a different path, working hours had an indirect positive influence on academic achievement through parents' different treatment which especially focused on the fact that parents gave students more freedom compared to the relationship they shared before the students began to work. Enjoying school, studying homework, and extra reading were influenced by students' number of working hours. Two variables, extra reading and job characteristics, predict the social acceptance work attitudes which are a direct predictor of occupational aspirations. Academic achievement had a greater total effect on the level of occupational aspirations than any other variables.

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STUDY ON THE DEFORMATION OF DROPLETS IN A TWO-DIMENSIONAL CHANNEL FLOW (2차원 채널유동에서의 액적 변형에 대한 수치해석적 연구)

  • Jung, S.R.;Cho, M.H.;Choi, H.G.;Yoo, J.Y.
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.6-9
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    • 2011
  • In this study, the two-phase incompressible flow in two-dimensional channel considering the effect of surface tension is simulated using an improved level-set method. Quadratic element is used for solving the continuity and Navier-Stokes equations to avoid using an additional pressure equation, and Crank-Nicholson scheme and linear element are used for solving the advection equation of the level set function. Direct approach method using geometric information is implemented instead of the hyperbolic-type partial differential equation for the reinitializing the level set function. The benchmark test case considers various arrays of defomable droplets under different flow conditions in straight channel. The deformation and migration of the droplets are computed and the results are compared very well with the existing studies.

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A Study on the Extension of the Extraterritorial Application of U.S. Antitrust Law and Our Corresponding Strategies (미국(美國) 반(反) 트러스트법(法)의 역외적용확대(域外適用擴大)와 그 대응방안(對應方案))

  • Bae, Jung-Han
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
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    • v.12
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    • pp.555-586
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    • 1999
  • United States has extended the extraterritorial application of U.S. Antitrust Law in 1990s. First, The U.S. Federal Supreme Court declared in Hartford Fire Insurance Co. v. California that the extraterritorial application of U.S. Antitrust Law is according to Effect Doctrine. Therefore, U.S. Antirust Division and FTC will continue to base their assertions of juridiction on the test of direct, substantial and foreseeable effects on U.S. interests. Second, U.S. Antitrust Law apply to foreign conduct that such conduct has direct, substantial and reasonably foreseeable effect on U.S. domestic or import commerce and export commerce. Third, United States has extended the extraterritorial application of U.S. Antitrust Law on international licensing contract or international merger. Forth, United States impose criminal responsbility of U.S. Antitrust Law on the foreign anticompetitive conduct. Therefore, our government and industries must consider the corresponding stratigies against the extension of the extraterritorial application of U.S. Antitrust Law.

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Shear Strength and Deformation Behavior of Rock Joint with Roughness (절리면의 거칠기에 따른 암석 절리의 전단강도 및 변형거동에 관한 연구)

  • 이상돈;강준호;이정인
    • Tunnel and Underground Space
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    • v.4 no.3
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    • pp.261-273
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    • 1994
  • Direct shear tests were carried out on the rock joints and artificial discontinuities to investigate the influence of joint roughness on the shear strength and deformation behaviour. Single direct shear testing apparatus used in experiment was designed and manufactured. Its capacity is 200 tons of shear load, 20 tons of normal load and 50$\textrm{cm}^2$ of maximum shear area. Test samples were cement mortar with artificial discontinuity and sandstone with natural joint. Peak shear strength was increased as joint roughness or normal stress was increased, especially, linearly increased with roughness angle in cement mortar. If joint roughness angle was constant at low normal stress, shear strength was not affected by width and height of joint roughness in cement mortar. Peak shear strengths obtained from tests were larger than the values calculated by Barton's equation, and shear stiffness was increased with joint roughness coefficient.

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MULTIPLE OUTLIER DETECTION IN LOGISTIC REGRESSION BY USING INFLUENCE MATRIX

  • Lee, Gwi-Hyun;Park, Sung-Hyun
    • Journal of the Korean Statistical Society
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    • v.36 no.4
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    • pp.457-469
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    • 2007
  • Many procedures are available to identify a single outlier or an isolated influential point in linear regression and logistic regression. But the detection of influential points or multiple outliers is more difficult, owing to masking and swamping problems. The multiple outlier detection methods for logistic regression have not been studied from the points of direct procedure yet. In this paper we consider the direct methods for logistic regression by extending the $Pe\tilde{n}a$ and Yohai (1995) influence matrix algorithm. We define the influence matrix in logistic regression by using Cook's distance in logistic regression, and test multiple outliers by using the mean shift model. To show accuracy of the proposed multiple outlier detection algorithm, we simulate artificial data including multiple outliers with masking and swamping.

Applicability Evaluation of the Characteristics Equation for a Coefficient of Permeability of Unsaturated Soils (불포화토의 투수계수 방정식의 적용성 평가)

  • Lyu, Tae-Jin;Song, Chang-Seob;Lim, Seong-Yoon
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2005.10a
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    • pp.393-398
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    • 2005
  • In order to treat flow problems for an unsaturated soils, it is required the mediation of the coefficient of permeability with variation of suction. The coefficient of permeability for soils can be determined by the direct or indirect methods. The direct methods of permeability can be performed either in the laboratory or in the field. The indirect methods can be predicted from the soil-water characteristics curve. Laboratory test methods to measure the coefficient of permeability can be categorized into two types, steady-state and unsteady-state. In this study, the coefficient of permeability for unsaturated soils was determined by the modified apparatus for steady state-method(Klute, 1972) and was predicted from the equations of Brooks and Corey(1964) and Van Genuchten(1980). Experimental results were compared with predicted coefficient of permeability and verified applicability of the two equations.

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An Experimental Study on the Spray Behaviors of Swirl and Slit Injector to Direct Injection Spark Injection Engine (DISI 엔진용 스월인젝터와 슬릿인젝터의 분무 거동에 관한 연구)

  • Lee Changhee;Lee Kihyung;Choi Youngjong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.1
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    • pp.19-27
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    • 2005
  • The spray characteristics of DISI injector has a great role in engine efficiency and emission. Thus, many researchers have been studied to investigate the spray characteristics of hollow cone type and slit type injector which are used in DISI engine. In this study, we tried to provide spray parameters which effect on the spray characteristics such as injection pressure, ambient pressure and ambient temperature. In addition, we calculated $t_b\;and\;t_c$ to investigate the break up mechanism of test injectors and also obtained $C_v$ to evaluate the spray characteristics. From this study, As the ambient pressure increases in case of slit injector, $C_v$ decreases.