• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.81-89
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• 2022

It is necessary to increase the surface hardness and improve the wear resistance and peeling resistance through the surface treatment and performance evaluation of the mold steel. As a result of vacuum heat treatment analysis, residual austenite measurement and surface treatment wear test, retained austenite should be removed by sub-zero treatment, and retained austenite was completely removed by treatment at -196℃. The TiMon film coated on the sub-zero treated STD11 specimen showed the lowest coefficient of friction.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.121-122
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• 2023

This study investigates the anti-corrosion properties of two eco-friendly pyridinium ionic liquids; 4DMN and 4DMP, in a 3.5% NaCl solution. Utilizing weight loss tests, EIS, PDP, quantum chemical calculations, and molecular dynamics simulations, the study demonstrates concentration-dependent inhibition efficiencies of 94% and 92% for 4DMN and 4DMP, respectively. The compounds modulate both anodic and cathodic reactions without altering the corrosion mechanism. EIS data suggest that a protective layer forms, supported by FE-SEM and AFM surface analyses, which reveal improved morphology and reduced roughness. Computational validations corroborate these empirical findings, highlighting the feasibility of these ionic liquids for effective, sustainable corrosion mitigation.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.9 no.1
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• pp.3-12
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• 1998

The present study compared the self report and parental report on the behavior problems of adolescents as a way to explore similarities and differences in the ways that adolescents and their parents conceptualize behavior problems of adolescents. Specifically, K-CBCL and YSR data from 3271 adolescents between the ages of 12 and 17 were subjected to factor analyses. Five factors；Depression/Anxiety/Withdrawal, Aggressiveness, Somatic Symptom, Disruptiveness, Attention Getting were obtained from the YSR data with the first factor, Depression/Anxiety/Withdrawal explaining 14.23% of the total variance. K-CBCL data yielded somewhat different factor structure with Aggression/Delinquency as the first factor explaining 14.08% of the total variance, followed by Somatic Symptoms, Social Withdrawal, Disruptiveness, and Depression/Anxiety. Total K-CBCL and YSR score showed a moderate correlation(r=.51), and correlation between pairs of comparable K-CBCL and YSR factor scores were also moderate. Regression analyses of the variables contributing to the total problem score of the K-CBCL and YSR suggested that social competence and academic achievement are two important sources of influence on the evaluation of behavior problems both in self-report and parental report. However, externalizing problems such as aggressiveness/delinquency appeared to be more salient for parents, while adolescents themselves appeared to be more concerned with internalizing problems such as depression/anxiety. Implications of these subtle differences for assessment of adolescent behavior problems were discussed.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.109-115
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• 2019

The objectives of this study was to analyze the importance and satisfaction (ISA) of forest healing instructor training program, targeting on the students educated in 2018. As a result, it was found that students older than forties are the majority as 81 %, and they preferred forest healing instructors as their second future job. When comparing the importance and satisfaction, the students evaluated satisfaction with low grade compared to importance with high grade in all questions. In ISA analysis, it was needed to improve the updated textbook information, to list the example problems by subject, to expose the test subjects in the textbooks, to disclose the test questions and answers, to control the test difficulty, to adjust the test pass rate, to expand the number of test and test sites, to increase the effort for making students understand, to prepare lectures appropriate to practice for forest healing instructor training program by priority.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.24 no.4
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• pp.133-152
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• 2013

This study strives to perform a pilot collection assessment study with the political science collection in a university library. Employing the basic list-checking analysis method, the study scrutinized the collection statistics and the circulation statistics, and check the current library holdings with a standard list which was composed of cited works extracted from course syllabi, theses, dissertations and faculty research papers. Although the study is a pilot case study that a particular model was applied to a collection in the field of political science, the result and procedures of the assessment will provide some implications regarding collection assessment in university libraries.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.464-470
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• 2010

The integrity of the industrial equipment in use under high temperature and high pressure must be assessed by regularly measuring the degraded mechanical properties during service time. In order to nondestructively monitor the degraded mechanical properties of industrial equipment, a measuring method of the reversible permeability(RP) using surface type probe is presented. The method for measuring the RP is based on that RP is the differential value of hysteresis loop. The RP is exactly the foundation hatmonics induced in a detecting coil measured by lock-in amplifier tuned to a frequency of the alternating perturbing magnetic field. The peak of RP is measured around the coercive force. Steel material used in this work was 12Cr ferritic heat resisting steel. The eleven kinds of samples aged during different times under same temperature ($700^{\circ}C$) were prepared. Peak interval of reversible permeability(PIRP), Vickers hardness, and tensile strength measured for the aged samples decreased abruptly for short aging time (below 500 h), but the change became small at a long aging time. Vickers hardness and tensile strength linearly decreased as RIRP decreased, so the degraded mechanical properties of 12Cr ferritic heat resisting steel could be nondestructively evaluated by measuring RIRP.

• Journal of The Korean Association For Science Education
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• v.20 no.2
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• pp.200-213
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• 2000

This study is to examine how common science, which was selected as a required subject in high schools with the reorganization of the 6th national science curriculum by the Ministry of Education, is taught in high schools these days. The results show that only one teacher is teaching common science in 3.2% of schools or the teachers divide and teach units according to their majors. In this situation, there are many problems because there are too many integrated contents in each unit and they are too short to solve the study subject during the unit time of 50 minutes. Another problem is that there is no special laboratory for common science. For the knowledge part of common science, lecture-learning is used as a method of teaching and for the inquiry part, inquiry-learning is used. Evaluation is conducted using subjective or objective paper-tests for the knowledge part, and reports are used for evaluation in the inquiry part. Therefore, this study shows that students' response to common science is below the general level and this subject missed the original intent introduced to raise students' interests about science.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.4
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• pp.258-271
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• 2010

In order to figure out hydrodynamic and water quality changes after completion of dike construction of the Saemangeum, which behaves as a semi-enclosed estuarine lake, numerical simulations based on fine grid structure by using EFDC were intensively carried out. In this study some limitations of precedent study has been improved and gate operation were considered. Also 3 phases such as air-water-sediment interaction modeling was considered. It is clear that inner mixing of the Saemangeum is dominated by Mankyeong and Dongjin riverine discharges rather than the gate opening influence through the Lagrangian particle tracking simulations. Vertical DO structure after the dike completion shows steep gradient especially at Dongjin river estuary due to lessen of outer sea water exchange. Increasing SOD at stagnantly changed man-made reservoir might cause oxygen deficiency and accelerating degradation of water quality. According to TSI evaluation test representing eutrophication status, it shows high possibility of eutrophication along Mankyeong waterway in spite of dike completion, while the index is getting high after final closing along Dongjin waterway. Numerical tests with gate operations show significant differences in water quality. Thus it should be noted that proper gate operation plays a major role in preserving target water quality and management for inner development plan.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.64-71
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• 2005

The welding methods have been applied to the most structural products used in the automobile, ship construction, and construction. The structure steel must have sufficient strength of structure; However, the mechanical properties of the welded part changes when it is welded. Therefore, the stability or life of the structure may be affected by the changed mechanical properties. The mechanical properties of the welded part must be examined in order to ensure the safety of structure. In this research, the SS400 steel and the STS304 steel were used to estimate the mechanical properties of the HAZ by weld thermal cycle simulation. In this study, the materials were used to examine the weld thermal cycle simulation characteristic, under two conditions: the drawing with diameter of $\Phi$10 and the residual stress removal treatment. To examine the mechanical properties by the weld thermal cycle simulation, the tensile test was carried out in room temperature. The crosshead speed was lmm/min.

• Journal of Ocean Engineering and Technology
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• v.22 no.6
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• pp.27-34
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• 2008

The temperature distribution in the weldment is not uniform because a weldment is locally heated. Thermal plastic deformation results from the local expansion and shrinkage by the heating and cooling of metal. Therefore, residual stresses and distortion occur in the weldment. In this study, we had conducted on the weld thermal cycle simulation that is supposed as the HAZ on SS400 steel and STS304 steel. The residual stresses that were obtained from the drawing and the weld thermal cycle simulation were estimated by X-ray diffraction. We also carried out ultrasonic test for the weld thermal cycle simulated specimens, and then conducted on nondestructive evaluation by the ultrasonic parameters obtained ultrasonic test. From the results, residual stresses of weld thermal cycle simulated specimens after the residual stress removal heat treatment are lower than that of the drawing.