• 대한기계학회논문집A
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• 제33권10호
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• pp.1177-1186
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• 2009

High temperature steam pipes of thermal power plant are subject to a severe thermal range and usually operates well into the creep range. Cyclic operation of the plant subjects the piping system to mechanical and thermal fatigue damages. Also, poor or malfunctional supports can impose massive loads or stress onto the piping system. In order to prevent the serious damage and failure of the critical piping system, various inspection methods such as visual inspection, computational analysis and on-line piping displacement monitoring were developed. 3-dimensional piping displacement monitoring system was developed with using the aluminum alloy rod and rotary encoder sensors, this system was installed and operated on the high temperature steam piping of "Y" thermal power plant successfully. It is expected that this study will contribute to the safety of piping system, which could minimize stress and extend the actual life of critical piping.

• 대한예방한의학회지
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• 제19권2호
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• pp.145-157
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• 2015

Objective : This study aimed to analyze a comprehensive feature of experimental research on Insamyangyoungtang and develop a strategy that can be used for experimental studies on Insamyangyoung-tang in the future. Method : The journal search was performed using six databases : PubMed, Chinese database (China Network Knowledge Infrastructure, [CNKI]), Japan database (Japan Science and Technology Information Aggregator, Electronic, [J-STAGE]) and three Korean databases (Oriental Medicine Advanced Searching Integrated System [OASIS], Research Information Service System [RISS], and Korean Studies Information Service System [KISS]). We used limited keywords and analyzed studies by publication year, experimental models, and the subjects of biological activities. The mechanism of pharmacological activity in accordance with the therapeutic effects of Insamyangyoung-tang was noted. Results and Conclusion : A total of 43 studies (6 domestic studies and 37 foreign ones) were examined according to the inclusion criteria of the experimental study. Research on the pharmacological activities of Insamyangyoung-tang showed its therapeutic effects on the nervous and immune systems, as well as its anti-aging, anti-fatigue, and hematopoietic effects. Additional efficacy and safety assessments and experimental and clinical studies should be performed to evaluate the mechanism of Insamyangyoung-tang. The present review has provided preliminary information for further studies on Insamyangyoung-tang.

• Tribology and Lubricants
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• 제32권1호
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• pp.18-23
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• 2016

The effective case depth for case-hardened rolling bearing has been discussed. For this purpose, rolling contact fatigue tests for ball bearings built with inner race of various hardness values were conducted until L₁₀ calculating rating life using a bearing life test machine under radial loading. Then, the distribution of residual stress below the inner raceway, which depended on the hardness value, was measured by X-ray diffraction. As a result, the linear relationship was established between the hardness value of the inner race and the theoretical shear stress evaluated at the depth where the residual stress disappeared below the inner raceway. Based on the relationship, it could be found that the factor of safety in bearing manufacturer’s rules for the effective case depth of case hardened rolling bearings was set higher. However, it could be also found that the hardness values at the depth where the maximum shearing stress acted below the raceway surface in a tapered roller bearing hardened by the carburizing process, were not sufficient for preventing plastic deformation under the basic dynamic load rating. Consequently, further efforts were still required to reduce or to disperse the contact load on the material design of a rolling bearing in order to prolong its life.

• 한국항공우주학회지
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• 제37권1호
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• pp.105-112
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• 2009

전투기가 임무수행중 기체에 발생할 수 있는 전투손상에 대처하기 위해 손상평가 및 수리설계, 구조건전성 평가방법 등 손상 후속절차를 연구하였다. 사례로서 F-15 ECS Bay에 발생한 전투손상에 대하여 ABDR(Aircraft Battle Damage Repair) 기술을 적용하여 손상평가 및 수리설계를 수행하고, 그 내용과 절차를 양식에 정리하였다. 또한, 정적강도 및 피로수명 계산과 같이 수리설계 구조의 구조건전성을 평가하여 비행안전 여부를 입증하고 영구수리 시점을 판단하였다.

• 대한조선학회지
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• 제4권1호
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• pp.59-65
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• 1967

Since the screw propellers were adopted as ship propulsion devices, the replacement of propeller shaft due to damage was mostly of fatigue failure due to the alternative stresses [1],[2]. To prevent such a failure, hence, it is suggested that careful attention should be paid to account of the alternative stresses on the design stage of the propeller shafts. In connection with this fact the Ship Classification Societies' Rules are regarded simply as guidance for preliminary determination of the shaft diameter. In this paper, limiting the topic to the small and medium-sized motor ships, an evaluation of the Rules formulae to a theoretical based on Soderberg's correlation [5] between the factor of safety and the resultant stresses obtained by application of the maximum shear theory is done. For this purpose eleven (11) ships built recently in Korea were taken as a species(refer to table 2. in text). In the end the following conclusions are made: (1) In general the Rules formulae give considerably larger size of the propeller shaft diameter than that derived from theoretical calculation, that is, about 7% more in AB and BV Rules, and about 20% more in LR and KR-NK Rules. (2) LR Rule gives the largest size of all, and AB Rule is mostly closed value to the theoretical. (3) The formular of the AB Rule is considered to be of the simplest in utilization and of the reasonable.

• 대한조선학회논문집
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• 제33권2호
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• pp.96-110
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• 1996

노후선박은 부식, 피로균열 등의 구조손상을 입고 있으며, 구조손상이 심각하면 중대한 해난사고를 초래할 위험성이 높다. 선각붕괴에 의한 선박의 침몰사고를 미연에 방지하기 위하여는 구조손상에 기인된 각종 불확실성을 고려한 노후선박의 최종강도 신뢰성을 평가할 필요가 있다. 본 논문에서는 부식에 의한 선체구조부재의 판두께 감소효과를 고려하여 선체구조의 최종강도를 기준으로한 신뢰성 평가기법을 제시하였다. 이를 위해 선체구조의 부식 속도모델을 선급에서 제시하는 데이타를 바탕으로 설정하고, 부식효과를 고려한 신뢰성 한계상태방정식을 도출하였으며, 최종강도 신뢰성은 SORM (second-order reliability method)을 적용하여 계산하였다. 본 기법을 이중선체 유조선에 적용하여 선령의 증가에 따른 단면계수 및 최종강도 신뢰성의 감소특성을 고찰하였다.

• 대한조선학회 특별논문집
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• 대한조선학회 2017년도 특별논문집
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• pp.38-45
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• 2017

FPSO is widely used to develop deep sea oil fields and HHI has constructed ten(10) FPSOs. During these constructions, relevant structural design criteria such as yielding, buckling, fatigue, collision and impact strength were applied to verify structural safety. To apply the buckling strength evaluation for structures, the critical buckling stresses and applied stresses of relevant panels should be calculated. The plate and stiffened panels are to be idealized, which are needed much time and efforts by designers. Therefore, program development is necessary in order to evaluate the buckling strength conveniently and accurately. In this study, the buckling strength assessment system by using offshore code, DNV-RP-C201 was developed under MSC/PATRAN, pre-post program of finite element method. Graphic user interface program is written in MSC/PATRAN PCL functions. Source program to evaluate the buckling strength is developed in FORTRAN programming languages. The developed program is verified by comparing with the results of the Nauticus Hull developed by DNV Classification Society, and applied to the marine construction project conducted by Hyundai Heavy Industries LTD.

• Structural Engineering and Mechanics
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• 제59권6호
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• pp.1095-1120
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• 2016

This paper investigates the change of structural characteristics of steel cable-stayed bridges after cable failure. Cables, considered as the intermediate supports of cable-stayed bridges, can break or fail for several reasons, such as fire, direct vehicle clash accident, extreme weather conditions, and fatigue of cable or anchorage. Also, the replacement of cables can cause temporary disconnection. Because of the structural characteristics with various geometric nonlinearities of cable-stayed bridges, cable failure may cause significant change to the structural state and ultimate behavior. Until now, the characteristics of structural behavior after cable failure have rarely been studied. In this study, rational cable failure analysis is suggested to trace the new equilibrium with structural configuration after the cable failure. Also, the sequence of ultimate analysis for the structure that suffers cable failure is suggested, to study the change of ultimate behavior and load carrying capacity under specific live load conditions. Using these analysis methods, the statical behavior after individual cable failure is studied based on the change of structural configuration, and distribution of internal forces. Also, the change of the ultimate behavior and load carrying capacity under specific live load conditions is investigated, using the proposed analysis method. According to the study, significant change of the statical behavior and ultimate capacity occurs although just one cable fails.

• 지역사회간호학회지
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• 제18권1호
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• pp.90-101
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• 2007

Purpose: The purpose of this study was to investigate influencing factors of health problems which the vinyl house farmers had experienced. Method: Based on PRECEDE model, this study was done with 110 respondents(50 to 69 years old), working in vinyl house and living in the remote area where the primary health post located. Results: Quality of life was low in economical status, emotional status, and physical function. Health problems were founded as pain and chronic fatigue that were caused by physical symptoms, weakened physical strength, and increased blood pressure and cholesterol. Behavioral and environmental factors were related with lack of exercise, irregular eating habit, curtailed sleep, overwork, wrong working postures, stress, and non-fulfillment of safety standard during spraying pesticide. Self efficacy was low in excercise practice, working way, and stress management. Conclusion: The Health Promotion Program for vinyl house farmers should be developed to improve health promoting behavior and self efficacy, to reduce stress, and to strengthen physical function.

• 지역사회간호학회지
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• 제27권4호
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• pp.337-345
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• 2016

Purpose: This study aims at identifying individual- and school-level factors associated with unintentional injuries to Korean adolescents at school by applying multilevel modeling. Methods: From the database of the eleventh Korea Youth Risk Behavior Web-based Survey (KYRBS), the researchers selected 68,043 adolescents from the $7^{th}$ to the $12^{th}$ grades. Data were analyzed using ${\chi}^2$ test for prevalence and multilevel modeling for related factors of unintentional injuries at school. Results: About 22.9 percent of the adolescents had treatment experiences for unintentional injuries at school in the past 12 months. At the individual level, the significant factors associated with unintentional injuries at school included gender, grade, academic achievement, current smoking, alcohol consumption, frequency of high caffeine intake, depression, and relief of fatigue after sleep. At the group level, the significant factors included number of physical education per week and safety education. Conclusion: School based injury prevention programs should be sensitive to both individual- and school-level factors associated with unintentional injury at school among Korean adolescents.