• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.201-210
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• 2011

This paper presents a nonlinear finite element analysis procedure for the seismic performance assessment of deep beam-and-interior column joints. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Horizontal cyclic load tests were conducted to estimate the strength, ductility, and behavioral characteristics of deep beam-and-interior column joints. Experimental parameters are axial forces and amount of transverse reinforcement. The proposed numerical method for the seismic performance assessment of deep beam-and-interior column joints is verified by comparison of its results with reliable experimental results.

• Journal of Korean Elementary Science Education
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• v.20 no.1
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• pp.107-122
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• 2001

The Purpose of this study is to find the effects of the portfolio assessment on elementary students' scientific knowledge, inquiry process skill, scientific attitudes in the teaching of science. And finally the parents' response to the portfolio assessment is also investigated. In order to reach the goal of this study, the investigator developed the evaluation instrument such as an experimental report and a cumulative observation sheet for the 4th-grade Unit-1 'Light Propagation' and Unit-3 'Separating Mixtures', and then these were administered to 42 4th-grade elementary students in Inchon. Based upon the findings and within the limitations of this study, several conclusions can be drawn regarding the problems investigated. First, as the portfolio assessment offers enough information about individual student's performance, it has a highly positive effect on evaluating the students' scientific knowledges. It can also make possible to grasp the several aspects of the student's progress. Second, the portfolio assessment can be implemented without giving students any psychological pressure from testing itself. Therefore, the portfolio assessment is an effective means of appraising inquiry process skills. Third, the portfolio assessment is effective to evaluate the students' attitude toward science by means of individual records which include such aspects that is hardly found by the teacher who teaches science in the class. Fourth, as most parents showed a positive response to this portfolio assessment, it is considered to be effective method of appraising the result of teaching science at elementary school. Accordingly, this study demonstrated that the portfolio assessment is an effective method that can assess students' scientific knowledges, inquiry process skills, and scientific attitudes gained from science teaching-learning. Therefore, it is necessary to implement the portfolio assessment to other grade students as well in the following study where teacher may give more encouragements and suggestions to sti dents for the better learning motives. Also teachers should suggest more definite evaluation criteria to students so that they may improve the students' self and peer evaluation skills.

• Communications of Mathematical Education
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• v.31 no.4
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• pp.409-432
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• 2017

The purpose of this study is to find out the importance of process - based evaluation and to find a way to set up and operate the formative assessment which is getting attention. As one of the ways, we investigated the effect of formative assessment through student's interactive feedback on mathematics achievement and attitude of fourth grade students in elementary school. In order to conduct the study, two groups of homogeneous grades were selected. In the experimental group, formative assessment was conducted through student's interactive feedback. In comparison group, formative assessment was conducted through self - confirmation feedback. Statistical analysis of the results after the experiment showed that the formative assessment through student's interactive feedback was found to have a positive effect on the improvement of mathematics achievement. In addition, the formative assessment through student's interactive feedback positively changed the mathematics attitude. Therefore, this suggests that applicability of formative assessment through student's interactive feedback in elementary school classroom instruction, as well as implications for follow - up study for effective implementation of formative assessment.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.297-303
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• 2000

Damage estimation of a bridge structure is presented using ambient vibration data caused by the traffic loadings. The procedure consists of identification of the modal properties and assessment of the damage locations and severities. An experimental study is carried out on the bridge model subjected to vehicle loadings. Vertical accelerations of the bridge deck are measured at a limited number of locations. The modal parameters are identified from the free vibration signals extracted using the random decrement method. Then, the damage assessment is carried out based on the estimated modal parameters using the neural networks technique. The identified damage locations and severities agree reasonably well with the inflicted damages on the structure.

• Journal of Power System Engineering
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• v.21 no.1
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• pp.43-49
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• 2017

This work aims to investigate on the low cycle fatigue life assessment, which is adopted on the strain-life relationship, or better known as the Coffin-Manson relationship, and also the strain energy density-based model. The low cycle fatigue test results of Alloy 617 weldments under $900^{\circ}C$ have been statistically estimated through the Coffin-Manson relationship according to the provided strain profile. In addition, the strain energy density-based model is proposed to represent the energy dissipated per cycle as fatigue damage parameter. Based on the results, Alloy 617 weldments followed the Coffin-Manson relationship and strain energy density-based model well, and they were compatible with the experimental data. The predicted lives based on these two proposed models were examined with the experimental data to select a proper life prediction parameter.

• Ocean Systems Engineering
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• v.10 no.2
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• pp.163-179
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• 2020

Considering the huge demand of several types of subsea equipment, as Christmas Trees, PLEMs (Pipeline End Manifolds), PLETs (Pipeline End Terminations) and manifolds for instance, a critical phase is its installation, especially when the equipment goes down through the water, crossing the splash zone. In this phase, the equipment is subject to slamming loads, which can induce impulsive loads in the installation wires and lead to their rupture. Slamming loads assessment formulation can be found in many references, like the Recommended Practice RP-N103 from DNV-GL (2011), a useful guide to evaluate installation loads. Regarding to the slamming loads, RP-N103 adopt some simplifying assumptions, as considering small dimensions for the equipment in relation to wave length, in order to estimate the slamming coefficient C_S used in load estimation. In this article, an experimental investigation based on typical subsea structure dimensions was performed to assess the slamming coefficient evaluation, considering a more specific scenario in terms of application, and some reduction of the slamming coefficient is achieved for higher velocities, with positive impact on operability.

• 한국전산유체공학회:학술대회논문집
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• 1996.05a
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• pp.137-142
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• 1996

A new wall impaction model for spray and its assessment are described in this paper. The gas phase is modelled in terms of the Eulerian continuum conservation equations of mass, momentum, energy and fuel vapour fraction. The liquid phase is modelled following the discrete droplet model approach. The droplet parcel contains many thousands of drops assumed to have the same size, temperature and velocity components. The droplet parcel equations of trajectory, momentum, mass and energy are written in Lagrangian form. The new drop-wall interaction model is proposed, which is based on experimental investigations on individual drops, and it is applied for the general non-orthogonal gird. The model is then assessed through comparison with experiments over a wide range of test conditions of sprays. The results are in good agreement with experimental data.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.13 no.1
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• pp.16-39
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• 2017

This paper reviewed and summarized the experimental studies conducted during last three decades to evaluate the structural integrity and to establish the acceptance criteria for piping system of nuclear power plants (NPPs) under seismic loading condition. These experimental studies contain the results of large-scale piping system tests under excessive seismic loading as well as standard specimen tests, simplified piping specimen tests, and piping components tests under simplified dynamic and cyclic loading. These would be useful as a basis for establishing integrity assessment procedure and acceptance criteria for piping systems of NPPs under beyond design basis earthquake (BDBE) conditions, and also could be used in planing the scope and direction of further related researches.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.4
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• pp.227-234
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• 2005

In this study an experimental investigation was conducted to assesment of cutting ability for CBN ball end-milling, STD11 and NAK80 materials. The cutting force and surface roughness of the work-pieces were obtained in machining center. The assessment of CBN tools were inspected through the tool dynamotor and SEM. When $30^{\circ}$ negative rake angle, the wear and cutting force were good, surface roughness was better at cutting fluid during CBN cutting.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.486-491
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• 1996

The purpose of present study is to propose a improved damage detection and assessment algorithm that has its basis on the method of system identification. This method allows the use of composite data which is constitute of static displacements and eigenmodes. In the dynamic test, thecurvature and slope of mode shape are introduced to formulate the error responses. The effectiveness of the proposed staristical system identification method is investigated through simulated and experimental studies. Real test data obtained from measurements are used to identify the actual location of damage and to revise the design variables in a concrete structure.