• Title/Summary/Keyword: Strength evaluation system

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Analysis on the Middle School Teachers' Level of Interest of Achievement Standards-based Assessment (성취평가제에 대한 중학교 교사의 관심수준 분석)

  • Kim, Suk-Woo
    • Journal of Fisheries and Marine Sciences Education
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    • v.26 no.1
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    • pp.81-97
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    • 2014
  • The purpose of this study is to analyze the level of interest in the achievement evaluation system, under the assumption that the teacher is an important element of curriculum. For this study, surveys targeting the 150 middle school teachers from 6 schools in Pusan was conducted. A questionnaire based CBAM model was used as research tools. For data analysis, mean of relative strength by teacher's level of interest was calculated. And MANOVA was used to investigate the difference among level of interest according to teachers' background such as sex, age, career, job position, and the grade they taught. The results of the analysis are summarized as follows. First, the middle school teachers' overall interest for achievement evaluation system is low. Teachers showed a typical pattern appeared in the early stages of change. They have little interest in the achievement evaluation system. And they should try to fix and change the achievement evaluation system rather than cooperate it. Second, as a result of this analysis of the difference according to teachers' background, no significant differences were found in most of the variables. Significant differences were found only in age, career, and job position from step 0. In running the post hoc, teachers who have less careers, lower positions, and younger ages had less interest in achievement evaluation system.

Evaluation on Strength Characteristics of Automobile Steel Sheet by Electrode Resistance Spot Weld (전기저항 점용접한 자동차 강판의 강도특성평가)

  • Yoon, Han-Ki;Hu, Kwan-Do;Ryu, Deok-Seang
    • Journal of Power System Engineering
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    • v.17 no.4
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    • pp.115-119
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    • 2013
  • The resistance spot welding of high strength steel degrades the weldability because of its high strength with rich chemical composition and coating layer to protect from corrosion. And the weld Expulsion is prone to occur and severely affect the nugget guality when the initial gap between automatic borrowing galvanied steel sheets(SGARC35) and Zn-coateel trip steels(GA580TRIP and GA980 TRIP) exist in resistance spot welding(RSW). RSW is one of the most popular welding processes used to join sheet metals. but weld guality sometimes do creases due to welding condition. in this paper to verity tue weldability using spot welding with the hemispherically concaved electrode, tensile shear strength and cross-tensile strength were measured by a universal test machine. in addition, the nugget size on cross-sectional area of the weld was observed by optical and electron microscopy. As a result, the nugget size of this specimen is increased with increasing welding current and Max load of tensile-shear strength is increased with welding current is increasing.

Optimization on Bar-to-Bar Similar Friction Welding of Hydraulic Valve Spool Steels and the Weld Strength Properties and its AE Evaluation (유공압밸브스풀용 강재의 봉 대 봉 동종대 마찰용접의 최적화와 용접강도 특성 및 AE품질 평가)

  • 오세규;이경우;전태언;오명석;이원석
    • Journal of Ocean Engineering and Technology
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    • v.10 no.2
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    • pp.69-76
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    • 1996
  • In-process quality control and high reliability of the weld are the major concerns in applying friction welding to the economical and qualified mass-production. Experimental examinations and quantitative analysis were performed for the optimiaztion of similar friction welding of hydraulic valve spool steels(SNCM220, SCM435, SACM645, SCM415, ${\varphi}24). The quantitative correlations were found between the initial cumulative counts of acoustic emission(AE) occurring during plastic deformation periods of the welding and the fatigue life as well as weld strength and welding conditions. A real-time evaluation system was developed for the friction weld quality by AE.

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Seismic Performance Evaluation of Existing Buildings Using Equivalent Double Diagonal Strut Model for Corrugated Steel Plate Walls (파형강판벽의 등가 양방향 대각 스트럿 모델을 이용한 기존 건물의 내진성능 평가)

  • Lee, Chang-Hwan;Son, Joo-Ki
    • Journal of Korean Association for Spatial Structures
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    • v.20 no.1
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    • pp.87-94
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    • 2020
  • A corrugated steel plate wall (CSPW) system is advantageous to secure the strength and stiffness required for lateral force resistance because of its high out-of-plane stability. It can also stably dissipate large amounts of energy even after peak strength. In this paper, a preliminary study has been carried out to use the CSPW system in the seismic retrofit of existing reinforced concrete (RC) moment frame buildings. The seismic performance for an example building was evaluated, and then a step-by-step retrofit design procedure for the CSPW was proposed. An equivalent analytical model of the CSPW was also introduced for a practical analysis of the retrofitted building, and the strengthening effect was finally evaluated based on the results of nonlinear analysis.

Evaluation on the condition and quality of railway track substructure (궤도노반의 상태 및 품질평가에 관한 연구)

  • Kim, Dae-Sang;Park, Tae-Soon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.346-353
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    • 2005
  • Track substructure(ballast, subgrade) should have sufficient strength and adequate stiffness to fully support track superstructure(rail, fastener, sleeper). Vertical support stiffness of track comes from the sufficient thickness, adequate strength and stiffness of material of substructure layers. Since the vertical support stiffness of track substructure is closely related with the track geometry, the evaluation of the stiffness is very important to understand the track states. This paper introduces the system, which are composed of Ground Penetrating Radar(GPR), Portable Ballast Sampler(PBS), and Light Falling Weight Deflectometer(LFWD), to evaluate substructure condition and summarizes the field test results performed with the reliable system.

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Optimum Evaluation of PS Concrete Deck and High Strength Two Plate Girder System (PS 콘크리트 바닥판 및 고강도 2주형 거더 시스템의 최적설계평가)

  • 박태훈;박문호;조창근;권민호;남유석
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.185-192
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    • 2003
  • This study presents the Optimum Evaluation of PS Concrete Deck and High Strength Two Plate Girder System. Recently, for the simplification of structure and the long length of bridge, a small number girder bridge which minimized a number of girder by two is much designed and constructed. For the structural analysis, a finite element formulation considering with even the matter of torsion in the three-dimensional problem is presented. And connectively, for the design of optimum section, an algorithm of optimum design is developed. The section of a small number girder bridge which constituted of two girders and PS Concrete Deck is optimized by using optimum program developed in this study. and two girders bridge refered in this study is proved a efficiency and a economy by being compared and checked to the general plate girder bridge with five girder and Reinforced Concrete Deck.

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Evaluation of Electrochemical Characteristic and Investigation on Optimum Condition in Friction Stir Welding for 6061-T6 Al Alloy (6061-T6 합금의 최적 마찰교반 용접 조건 규명 및 전기화학적 특성 평가)

  • Kim, Seong-Jong;Jang, Seok-Ki
    • Journal of the Korean institute of surface engineering
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    • v.41 no.6
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    • pp.341-350
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    • 2008
  • In friction stir welding for 6061-T6 with various traveling speed and rotation speed conditions, the best mechanical characteristics presented in traveling speed of 507 mm/min and rotation speed of 1100RPM. The maximum tensile strength and yield strength increased with the increasing of traveling speed. The result of the electrochemical characteristic evaluation in friction stir welding at optimum conditions for 6061-T6 Al alloy presented a good characteristics compare to base metal.

Evaluation of Bearing Strength for Composite Joint (합성접합부에서 지압내력 평가식)

  • 김병국;최완철
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.347-352
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    • 2002
  • Recent trends in the construction of building frame feature the increase use of composite steel concrete members functioning together in what terms of mixed structural systems. One of such systems, RCS(reinforced concrete column and steel beam) system is introduced and closely examined focusing on bearing strength of the composite joint in this paper. The main objective of this study was to develope one of details to increase bearing capacity while bearing failure is one of the two primary modes of failure in RCS system. Local bearing tests with specimens about 1/3 of the actual concrete column size were performed applying uniform load through steel plate with 100$\times$110mm size. Test results show that specimens with the bearing reinforcement detail developed in this study enhanced the bearing strength by 1.71~3.02 compared to concrete cylinder strength.

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Estimation of Probability Distribution of Fatigue Lives in Crank Throw Forged Steel (크랭크스로 단조강의 피로수명의 확률분포 추정)

  • Kim, Seon-Jin;Ahn, Seok-Hwan
    • Journal of Power System Engineering
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    • v.20 no.3
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    • pp.29-35
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    • 2016
  • Because of the severe service environment of the large marine vessel, the fatigue strength and its evaluation play an important role in design and maintenance of marine crankshaft. The aim of this work is to investigate the probability distribution of fatigue lives in crank throw forged steel and to develop the methodology for estimation of the probabilistic design fatigue strength. Detailed studies were performed on the constant amplitude axial loading fatigue test. The experiments were controlled by stress ratio of -1 and 15Hz frequency for each stress level. The considerable variability of fatigue life was observed in each stress level under rigidly controlled constant fatigue testing conditions. The fatigue life of crank throw forged steel was well followed the log-normal and Weibull distribution. In addition, it can be used for the estimation of probabilistic design fatigue strength by using the proposed methodology.