• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.191-208
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• 2024

In this study, a hydro-mechanical-damage coupled analysis model was developed to evaluate the structural safety of radioactive waste disposal structures. The Mazars damage model, widely used to model the fracture behavior of brittle materials such as rocks or concrete, was coupled with conventional hydro-mechanical analysis and the developed model was verified via theoretical solutions from literature. To derive the numerical input values for damage-coupled analysis, uniaxial compressive strength and Brazilian tensile strength tests were performed on concrete samples made using the mix ratio of the disposal concrete silo cured under dry and saturated conditions. The input factors derived from the laboratory-scale experiments were applied to a two-dimensional finite element model of the concrete silos at the Wolseong Nuclear Environmental Management Center in Gyeongju and numerical analysis was conducted to analyze the effects of damage consideration, analysis technique, and waste loading conditions. The hydro-mechanical-damage coupled model developed in this study will be applied to the long-term behavior and stability analysis of deep geological repositories for high-level radioactive waste disposal.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.195-195
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• 2021

최근 기후변화, 과도한 지하수 이용 등으로 유역 환경이 변화하고 있으며, 이에 따른 부작용으로 하천의 건천화, 지표유출량 증가, 증발산량 감소 등 물순환 구조가 왜곡되고 있다. 물순환 과정은 지역적 조건에 따라 다르게 나타나며, 모의 요소와 해석 기법도 다르다. 따라서 지속가능하고 건전화된 물순환을 위해 해당 유역의 물순환계를 정확히 파악하고 고려하여 객관적으로 정량화할 수 있어야 한다. 현재 우리나라 농업유역은 논, 용·배수로, 농업용 저수지가 존재하며, 종합적인 농촌용수 물순환 해석을 위해 농촌용수 요소별 해석 기술 및 모듈 개발, 모델링 기법 등을 이용하여 농촌수자원의 체계적·과학적 해석 및 관리 시스템 개발이 이루어져야 한다. 본 연구에서는 강원도 원주시에 위치한 흥업저수지를 대상으로 농촌용수의 물순환 과정을 정립하였으며, 저수지 시점부·말단부, 농업용 저수지, 저수지 유역으로 구분하여 물순환 분석을 수행하였다. 물순환 모의 요소로 저수지 수위, 유역 유출량, 수로부 공급량 및 배수량, 회귀수량 등으로 선정하였으며, 수로 네트워크 기반의 SWMM (Storm Water Management Model) 모형을 이용하여 종합적인 농촌용수 물순환 해석을 수행하였다. 또한, 물순환 해석 기법의 적용성 검증을 위해 모의 요소별 모니터링을 수행하였으며, SWMM 모형과 모니터링을 비교하여 적용성을 평가하였다. 본 연구 결과를 통해 농촌지역 특성 및 기후변화를 고려한 농촌수자원의 안정적인 공급과 국가 청정 수자원 확보를 위한 통합 물관리 정책을 실현하는데 기초 자료로써 활용 가능할 것이라 사료된다.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.2
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• pp.145-156
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• 2005

An artificial disturbance like forest fragmentation has affected the sustainability of forest ecosystem. Therefore, in order to manage the forest ecosystem efficiently needed to analyze quantity and quality (structural pattern) of forest simultaneously. This study analyzed the structural patterns of forest landscape to provide a basic data for evaluation and management of forest ecosystem in Nakdong River Basin during 10 years from 1980s to 1990s using landscape indices and GIS methods. Forest distribution maps and 6 landscape indices(LPI, PD, ED, MSI, CPLAND, IJI) for the analysis were reconstructed from land-cover maps constructed by Ministry of Environment and pearson correlation analysis. According to the structural analysis of forest landscape using landscape indices, the forest fragmentation of watersheds along the main stream of the Nakdong river was more severe than any other watersheds. Futhermore, the Nakong-sangju and Nakdong-miryang watersheds had unstable forest structures as well as least amount of forest quantity. Thus, these watersheds need significant amount of forest through a new forest management policy considering local environmental conditions. The connectivity between forests in local regions should be considered as well.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1179-1185
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• 2011

Cold and hot-rolled carbon steel sheets are commonly used in railroad cars or commercial vehicles such as the automobile. The sheets used in these applications are mainly fabricated by spot welding, which is a type of electric resistance welding. However, the fatigue strength of a spot-welded joint is lower than that of the base metal because of high stress concentration at the nugget edge of the spot-welded part. In particular, the fatigue strength of the joint is influenced by not only geometrical and mechanical factors but also the welding conditions for the spot-welded joint. Therefore, there is a need for establishing a reasonable criterion for a long-life design for spot-welded structures. In this thesis, ${\Delta}P-N_f$ relation curves have been used to determine a long-life fatigue-design criterion for thin-sheet structures. However, as these curves vary under the influence of welding conditions, mechanical conditions, geometrical factors, etc. It is very difficult to systematically determine a fatigue-design criterion on the basis of these curves. Therefore, in order to eliminate such problems, the welding residual stresses generated during welding and the stress distributions around the weld generated by external forces were numerically and experimentally analyzed on the basis of the results, reassessed fatigue strength of gas welded joints.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.75-79
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• 2023

ESG management means to thoroughly consider the investor's perspective when evaluating corporate value, and environmental, social, and governance issues are continuous and strategic monitoring issues in identifying risk and opportunity factors related to corporate management activities. In other words, the perspective of value creation is reflected in business relationships. The fundamental purpose of ESG management is continuous business value creation and thorough management of investment risks and business transactions in contractual relationships. It is also a requirement of linked investors. The field that Korean companies are currently experiencing the most is the recognition that 'ESG information collection is necessary and maintenance must be prioritized' in investor IR and global sales and marketing departments, and the primary need for this is emerging. In addition, as the legal affairs office, environmental safety department, and human resources department, which conduct compliance management, carry out related tasks, clarity at the organizational level must precede in order to properly establish an information integration and management system. It covers the scope of securing new market opportunities such as management, disclosure and communication. Therefore, in regard to the newly emerging ESG management and response methods, it is necessary to review and implement it repeatedly so that sustainable exchange profits can be created by simultaneously managing non-financial risks as well as efforts to enhance corporate value for financial returns.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.155-164
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• 2014

Carbon-fiber-reinforced plastic (CFRP) composites are increasingly being used in a variety of industry applications, such as aircraft, automobiles, and ships because of their high specific stiffness and high specific strength. Aircraft are exposed to high temperatures and high humidity for a long duration during flights. CFRP materials of the aircraft can absorb water, which could decrease the adhesion strength of these materials and cause their volumes to change with variation in internal stress. Therefore, it is necessary to estimate the characteristics of CFRP composites under actual conditions from the viewpoint of aircraft safety. In this study air-coupled ultrasonic testing (ACUT) was applied to the evaluation of water absorption properties of CFRP composites. CFRP specimens were fabricated and immersed in distilled water at $75^{\circ}C$ for 30, 60, and 120 days, after which their ultrasonic images were obtained by ACUT. The water absorption properties were determined by quantitatively analyzing the changes in ultrasonic signals. Further, shear strength was applied to the specimens to verify the changes in their mechanical properties for water absorption.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.9-16
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• 2019

Recently, precast PSC girder bridges have been widely applied for short and middle span bridges. The construction of the spliced girder bridges has been increasing to overcome the length limit of girder and transportation restrictions. In case of the spliced girder, the integrity of the segmental joints is very important to secure the structural soundness of bridge because the discontinuity on the segmental joints between adjacent segments could be vulnerable point. The study of segmental joint behavior with different influence factors of joint type, shear key installation, confining force is very important. In this research, finite element analysis and scaled model test with different shear key shapes and confining forces were carried out and the comparative study was performed to evaluate the segmental joint behavior of precast spliced PSC girder bridge. It was confirmed that the installation of shear key with height and depth ratio of 1/2~1/3 and applying of confining force of 1/2 of the concrete strength at the joint was effective in improving the integrity of segmental joint. In addition, the field loading test for existed precast spliced PSC girder bridge was performed and the measurement of the difference of deflection between adjacent segments at segmental joint was proposed as the assessment solution of the integrity of segmental joint.

• Journal of Welding and Joining
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• v.17 no.2
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• pp.25-28
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• 1999

국내에 건설되어 거의 20∼30년 가동되고 있는 발전설비, 석유화학 플랜트 등 거대설비 기기의 건전성(integrity) 및 신뢰성 확보와 잔존수명 예측을 위해서는 구조물 내부 또는 표층부에 존재하는 결 함의 특성을 아는 것과 함께 그 재료의 특정 부위에 어느정도의 응력이나 변형이 있는가를 아는 것이 매우 중요하다. 일반적으로 강 용접부의 비파괴적 결함검출에는 주로 SV파(vertically shear wave)와 SH파(horizontally shear wave)라 불리는 횡파를 이용한 초음파사각탐상법이 실용화되어 이용되고 있다. 그러나 비파괴적인 방법에 의한 실험적인 잔류응력 측정, 변형해석법에는 전기 저항 및 자기 스트레인 게이지법, X선회절법, 광탄성법(photoelasticity), 모아레(Mohr's)법, 레이저스펙클(Laser speackle)법, 응 력도료법, Barkhausen Nosise법, Caustics법 등이 제시되어 있으나 그 유용성 면에서는 아직 해결되야할 문제가 많이 남아 있는 실정이다. 응력이나 변형을 해석하는 방법으로 이론적 방법, 계산적 방법 실험적 방법이 잇다. 이론적 방법에는 재료 역학적으로 취급하는 방법, 탄성론 등이 있고, 계산적인 방법에는 유한요소법이 있지만, 이론적 방법이나 계산적 방법만으로는 해석이 불가능한 경우가 많기 때문에 실험 적 방법이 필요하게 된다. 이 글에서는 파괴 시험 또는 다른 비파괴평가기술에 비해 간편한 측정, 높은 측정정도, 시험결과 도출의 신속성, 검사비용의 절감 등 많은 장점을 가지고 있고 실험적으로 유용성이 일부 검증되고 있는 음탄성법(Acoustoelasticity)에 의한 잔류응력 측정법에 관해 소개하고자 한다.TEX> mg/L(평균 49 mg/L)로 비교적 안정적인 처리효율을 보여주었다. 본 연구결과 HVC 공정은 화학약품 사용량의 절감 및 이에 따른 화학슬러지 발생량의 감소를 기대 할 수 있는 친환경기술로 유지관리비를 최소화할 수 있는 장점이 있었다. 않은 사람들 중 미래의 검진실행의지에 건강소식지가 영향을 미친 경우는 48.7%였다. 보건교육을 받은 후 유방암 자가검진 실천율은 사업군에서 53.9%로 받기 전의 27.3%보다 증가하였으나 대조군의 경우는 별 차이가 없었다. 연령별로는 60대가 가장 높았고 사업군에서 검진율의 증가분은 30대가 가장 컸다. 교육수준별로는 사업군은 고졸이, 대조군은 전문대졸이 가장 높았고 사업군에서 검진율의 증가분은 고졸에서 가장 컸다. 보건교육 후 유방암과 관련된 건강지식의 정도는 사업군이 3.7점으로 대조군보다 유의하게 높았으며, 유방암 자가검진법을 실천하는 사람들의 동기는 ‘일반 대중매체의 영향’이 가장 많았으며 건강소식지가 동기인 경우도 20.4%였다. 사업군에서 건강소식지가 유방암 자가검진법 실천에 영향을 미친 경우가 79.6%였으며 유방암 자가검진법에 관한 보건교육을 받고 실천하지 않은 사람들 중 미래의 실천의지에 건강소식지가 영향을 미친 경우는 43.6%였다. 이상의 소견에서 지역주민을 대상으로 인쇄매체를 통한 보건교육은 인쇄물만으로도 쉽게 실천 할 수 있는 유방암 자가검진법이 가장 효과적이었으며, 자궁암검진에 관해서도 검진을 받을 수 있도록 지역사회의 보건의료의 하부구조를 정비하여 제도적 장치를 마련하고 정보를 제공한다면 자궁암검진 실천율도 증가할 것이다.고 12.9% 의 발달율을 보여 유의적인 차이를 보이지 않았다. 이상의 결과로 보아 핵이식 수정란을 효율적으로 생산하기 위하여

• Economic and Environmental Geology
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• v.51 no.2
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• pp.185-201
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• 2018

Nuclear power plants(NPP) are constructed and operated to ensure safety against natural disasters and man-made disasters in all processes including site selection, site survey, design, construction, and operation. This paper will introduce a series of efforts conducted in Korea Hydro and Nuclear Power Co. Ltd., to assure the safety of nuclear power plant against earthquakes and other natural hazards. In particular, the present status of the earthquake, fault, and slope safety monitoring system for nuclear power plants is introduced. A earthquake observatory network for the NPP sites has been built up for nuclear safety and providing adequate seismic design standards for NPP sites by monitoring seismicity in and around NPPs since 1999. The Eupcheon Fault Monitoring System, composed of a strainmeter, seismometer, creepmeter, Global Positioning System, and groundwater meter, was installed to assess the safety of the Wolsung Nuclear Power Plant against earthquakes by monitoring the short- and long-term behavioral characteristics of the Eupcheon fault. Through the analysis of measured data, it was verified that the Eupcheon fault is a relatively stable fault that is not affected by earthquakes occurring around the southeastern part of the Korean peninsula. In addition, it was confirmed that the fault monitoring system could be very useful for seismic safety analysis and earthquake prediction study on the fault. K-SLOPE System for systematic slope monitoring was successfully developed for monitoring of the slope at nuclear power plants. Several kinds of monitoring devices including an inclinometer, tiltmeter, tension-wire, and precipitation gauge were installed on the NPP slope. A macro deformation analysis using terrestrial LiDAR (Light Detection And Ranging) was performed for overall slope deformation evaluation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.543-550
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• 2018

The rapid growth of IoT technology induced by the fourth industrial revolution has resulted in research into various types of wireless sensors, and applications based on this technology are prevalent in many areas. However, among the various sites where this technology is used, railway bridges and tunnels with lengths of tens of kilometers have problems with data acquisition, due to the signal noise induced by the long distance measurement and EMI induced by the high voltage power feeding system, when conventional electric sensors are used. To overcome these problems, many studies on fiber optic sensors have been conducted as a substitute for the conventional electric sensors. However, restrictions on the types of fiber optic sensors have limited their application in railways. For this reason, a hybrid measurement system with IoT based wireless data communication, in which both electric and fiber optic sensors can be applied simultaneously, has been developed. In this study, in order to evaluate the applicability of the hybrid measurement system developed in the previous study, a real-time test for 4 types of measurement environments, which reflect possible railway sites, is performed. As a result, it was confirmed that the signals from both the electric and fiber optic sensors, which were acquired at a remote area in real-time, showed good agreement with each other and that this measurement system has the potential to handle sensors with a sampling rate of 2.5 kHz. In the future, it is expected that the IoT-based hybrid measurement system will contribute to the improvement of structural safety by enabling real-time structural health monitoring when applied to various measurement sites.