• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.169-172
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• 2008

Longitudinal elongation develops in reinforced concrete beams that exhibit flexural yielding during cyclic loading. The longitudinal elongation can decrease the shear strength and deformation capacity of the beams. In the present study, nonlinear truss model analysis was performed to study the elongation mechanism of reinforced concrete beams. The results showed that residual tensile plastic strain of the longitudinal reinforcing bar in the plastic hinge is the primary factor causing the member elongation, and that the shear-force transfer mechanism of diagonal concrete struts has a substantial effect on the magnitude of the elongation. Based on the analysis results, a simplified method for evaluating member elongation was developed. The proposed method was applied to test specimens with various design parameters and loading conditions..

• The Journal of Engineering Geology
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• v.19 no.1
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• pp.43-50
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• 2009

A 3-D numerical analysis was carried out to observe potential effects of orientation of inherent weak zones to tunnel behaviors and stress distributions during tunnel excavation. Weak zones used for the analysis were placed at the upper 1D part from crown, on the crown and on the center of face, using orientations derived from the 6th RMR parameter for assessment of joint orientation effect on tunnel. Mechanical properties of rock mass were derived through a in-situ displacement measurement-based back analysis. Finally, a classification chart for crown settlement with five ranks based on orientation and location of weak zones is suggested.

• Journal of Welding and Joining
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• v.6 no.1
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• pp.35-45
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• 1988

오-스테나이트계 스테인레스강에 대한 용접은 용접재료의 개발과 더불어 각종 산업계에 널리 이용되고 있으며 최근 Type 303 오-스테나이트계 스테인레스강 등은 free machining재로써 널리 응용되고 있다. 그러나 이 303계는 피삭성, 절삭성, 칩형성개선을 위한 특수원소(Se, S 등)의 첨가 때문에 용접성에 문제점을 제기하고 있다. 본 연구에서는 Type 303을 중심으로 AISI 304-316NG 및 347NG계의 오-스테나이트계 스테인레스강의 고온연성거동과 고온균열감수성(용접성)에 관한 연구에 대한 검토중 고온연성거동에 관하여 조사하였다. 고온연성평가는 Gleeble Simulator에 의하여 재료와 방향성에 따라 검토하였으며, 그 결과 모든 재료는 압연방향을 종방으로 시험하였을 때는 거의 유사한 고온연성을 나타내었으나 횡방향으로 시험하였을 때는 종방향에 비하여 연성저하를 나타내었다. 이와 같은 고온연성은 후속연구에서 검토될 고온균열 감수성과 밀접한 관련성에 의하여 용접성을 평가할 수 있다.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.1
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• pp.33-42
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• 2018

The purpose of this study is to suggest the shortcomings and the direction of the web accessibility evaluation studies by analyzing the research trends on web accessibility evaluation in Korea. For this aim, a total of 59 theses presented in the registered academic journal and the candidate of registration academic journals from January 2000 to March 2017 were selected. The selected dissertations have been analyzed based on the evaluators, the evaluation targets, the evaluation methods, and the evaluation results with regard to web accessibility. As a result of the analysis, the highest rate in the evaluator aspect was 'independent evaluation (66 percent)' and the highest percentage in the evaluation target aspect was 'web site (83 percent)'. When it came to the evaluation methods, automatic evaluation and the mixture of automatic evaluation and manual evaluation had a similar percentage. Lastly, only two papers showed that web accessibility did not have any problems. This study is meaningful in the sense that it suggested a desirable direction for the web accessibility studies in Korea and web accessibility evaluation studies in the situation when the meta studies which analyzed research trends are insufficient.

• Journal of Energy Engineering
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• v.28 no.3
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• pp.1-9
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• 2019

A major stress determining the remaining life of the tube in feedwater heater of fossil fuel power plant is hoop stress by the internal pressure. However, thermal stress due to temperature difference across the wall thickness also contributed to reduce the remaining life of the tube. Therefore, thermal loading must be considered even though the contribution of internal pressure loading to the stresses of the tube was known to be much higher than that of the thermal loading. In this study, thermal stress of the tubes in the de-superheating zone was estimated, which was generated due to the temperature difference across the tube thickness. Analytic equations were shown for determining the hoop stress and the radial stress of the tube with uniform thinning and for the temperature across the tube thickness. Accuracy and effectiveness of the analytic equations for the stresses were verified by comparing the results obtained by the analytic equations with those obtained from finite element analysis. Using finite element analysis, the stresses for eccentric thinning were also determined. The effect of heat transfer coefficient on thermal stress was investigated using series of finite element analyses with various values of heat transfer coefficient for both inner and outer surface of the tube. It was shown that the effect of heat transfer coefficient at outer surface was larger than that of heat transfer coefficient at inner surface on the thermal stress of the tube. Also, the hoop stress was larger than the radial stress for both cases of uniformly and eccentrically thinned tubes when the thermal loading was only considered without internal pressure loading.

• Journal of the Korean Society of Radiology
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• v.7 no.2
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• pp.137-143
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• 2013

This study presents comparison results between axial and spiral scanning in the head and chest region with 64 MDCT to evaluate organ doses in infants and toddlers, who are more radiosensitive to radiation than adults and rise in the number of CT examinations, during CT scanning. Organ doses were significantly lower in spiral scanning than axial scanning regardless of scanned regions. The average organ dose for the chest scan using pitch of 1.355 was found to be significantly higher(average -12.03%) than for the other two pitch settings(0.525 and 0.988) in the spiral scanning mode compared with the axial one. Organ doses in the spiral scanning mode were lower by average 20.54% than the axial scanning mode. The results of the study that evaluated organ doses with an anthropomorphic phantom will help to demonstrate the result values of Monte Carlo simulations and make a contribution to more accurate evaluations of organ doses in toddlers undergoing a CT examination.

• Journal of Korean Society of Steel Construction
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• v.19 no.1
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• pp.117-127
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• 2007

In this study, we evaluate the strength of steel box beam-to-column connections subjected to axial loads in steel frame piers. The T-connection strength was reduced due to the column axial force in the two-story pier structure. To examine this phenomenon, non-linear FEM analysis was carried out and the analytical procedure was verified by comparing it with experimental results. To clarify the effect of the axial force and major design parameters in connection with strength, influence of panel zone width-thickness ratio, sectional area, and axial force was investigated using FEM analysis. Also, the theoretical strength equations were suggested by stress distribution of panel zone. The strength of the T-connection was compared with one of the one-story pier structure connections. As a result, the strength evaluation equations are proposed in consideration of the panel zone width-thickness ratio and sectional area ratio for the T-connections.

• Science of Emotion and Sensibility
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• v.2 no.2
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• pp.83-91
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• 1999

사이버 채팅 시스템(Cyber Chatting System)은 한 명 이상의 참여자들이 사이버 공간에서 대화할 수 있도록 해주는 양방향 이사 소통 시스템이다. 컴퓨터를 통한 통신이 점차 확산되어 가면서 사이버 채팅 시스템도 그 중요도가 새롭게 인식되고 있고, 국내외로 많은 사이버 채팅 시스템이 운영 중에 있다. 사이버 채팅 시스템들도 다른 시스템들과 마찬가지로 사용자들이 원하는 서비스를 제공하고 있는가를 판단하고 개선 방향을 얻기 위해서는 사용성 평가를 받아야 한다. 기존의 일반적인 프로그램 평가 방식이나 웹 페이지 평가 방식만을 적용해서는 사이버 채팅 시스템의 특징을 반영하는 평가를 하기에 충분하지 않다. 그러므로, 본 논문에서는 사용자들이 일반 대화에서 얻은 정신 모형을 바탕으로 사용성 평가 방식을 개발하여 채팅 시스템의실질적 사용성을 분석할 수 있도록 하였다. 이러한 평가 시스템을 적용하면 사용자의 예상과 기대를 기반으로 시스템의 사용성을 평가하여 보다 나은 시스템 개발을 위한 개선 방향을 효과적으로 제시할 수 있다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2001.11a
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• pp.335-339
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• 2001

국외의 경우엔 일찍부터 컴퓨터 시스템 평가기준이 제정되어 활용중이나 국내의 경우엔 아직 평가기준이 없는 상태이다. 본 논문에서는 국내외 정보시스템의 보안 요구사항과 보증 요구사항을 바탕으로 리눅스 기반 PC의 보안성 평가기준을 제안하고자 한다. 평가등급은 KL(Korea Linux)1, KL2, KL3 등의 3등급으로 분류하였다. 제안된 평가기준은 오픈 소스기반의 리눅스를 이용하여 보안기능을 강화한 운영체제 개발방향을 제시하였고, 보안 시스템 구축의 방향 및 보안표준에 대한 복잡한 문제를 줄였다. 또한 국제공통평가기준(CC : Common Criteria)의 보안기능부분과 보증부분을 거의 수용함으로써, 외국의 보안성 평가기준과 상호 운용이 가능하다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.286-288
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• 2018

본 발표는 대한민국 해기사 커뮤니케이션 역량 강화를 위해, 해사 영어 구술시험 개발의 필요성을 타국의 사례 등을 통해 제안하고, 이를 위해 시범 개발 중인 "한국형 해사 영어 구술시험"의 개발 제작 과정과 현재 개발 진행 사항을 공유하고, 향후 추진 방향을 모색하기 위함이다. 따라서 본 발표에서는, 구술시험 평가 수립을 위한 유관 산업 문헌 조사(국제 교통 관련 산업 의사소통 지침, 평가 척도), 해기사 직무에 따른 영어 구술시험 문제 개발 계획 수립 및 시험 설계 시 검토 사항, 모의 구술시험 설계 및 시행, 모의시험 효과 측정, 측정 결과에 따른 향후 평가 척도 개발 시 고려 사항, 구술 평가를 인공지능 평가 방법 도입 방안 모색 등의 과정을 순차적으로 소개하고, 이에 대한 결과물을 공유하며, 향후 발전 방향을 제안하고자 한다.