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Enhancement of master curve method for inhomogeneous material
Shin-Beom Choi,Sung Choi,최재붕,Yoon-Suk Chang,Min-Chul Kim,Bong-Sang Lee 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.9
Although the well-known master curve method has been widely used to estimate the ductile to brittle transition temperature and to prevent subsequent brittle fracture of reactor pressure vessels, it has a limitation to determine reference temperatures on heat affected zone and weld metals. The present paper is to propose an enhanced master curve method. Prior to this, several schemes to provide the master curve of inhomogeneous materials such as bimodal master curve estimation, randomly inhomogeneous master curve estimation and single point estimation were reviewed to confirm their applicability. As a result, the single point estimation scheme was chosen as the basic algorithm to calculate the reference temperature and modified by adopting three T0sp parameters concept to enhance the accuracy. The proposed method can be used to inhomogeneous materials for more accurate reference temperature calculation of reactor pressure vessels even with dispersed fracture toughness test data.
Golden Time 확보를 위한 스마트 인명구조시스템 개발
최정우(Jungwoo Choi),김혜숙(Hyesook Kim),최재붕(Jaeboong Choi) 한국HCI학회 2016 한국HCI학회 학술대회 Vol.2016 No.1
본 연구에서는 야외 활동이 급증하면서 발생할 수 있는 사고를 줄이기 위한 목적으로 스마트 인명구조시스템을 소개한다. 미니 PC 로 불리는 라즈베리파이와 무선통신기술인 LTE 라우터의 결합으로 하드웨어와 소프트웨어를 통합적으로 디자인하여 효과적인 안전관리체계를 구축한다. 우선, 스마트 구조함 디자인은 하드웨어적 측면으로, 최저음압(dB)이 적용된 부저가 장착되어 사고발생 시구조함 문을 열거나 구명환을 꺼낼 때 센서의 신호를 인식하여 최적화된 경고음과 경고등이 작동한다. 또한 구조함 내부의 온도 및 습도 조절을 위한 쿨링시스템과 방수장치가 설계되었으며, 구조함 전체의 외관은 태양전지를 이용하여 에너지를 얻고 쓸 수 있도록 설계하였다. 다음으로, 스마트 인명구조의 시스템 구성은 소프트웨어적 측면으로, 구조함과 관리자간의 통신 체계를 효과적으로 운영하기 위한 유/무선 인터넷 통합 DB 서버를 구축한다. DB 서버와 스마트폰과의 연동을 위한 어플리케이션 디자인 개발과 구조함 관리자 전용 클리이언트 프로그램 개발로 구성하여 완성되었다. 스마트 안전관리시스템은 사고발생 시 사람의 생명을 구할 수 있는 골든 타임 확보에 매우 중요한 역할을 할 수 있을 것이다. This study was to develop a smart life-saving system combined with a life-saving box to secure the golden time in case of emergencies in outdoor activities. This system combined hardware and software designed to provide effective safety measure. As the hardware, the life-saving box has a buzzer operated by a pressure sensor which is activated to turn on alarm sounds and light when the box is open or the ring buoy is taken. The box also has a water-proof feature with cooler for temperature and humidity control. The smart life-saving system is operated by software that enables effective communication between the box and the manager via a database server through wired and wireless internet connection (based on raspberry pi and LTE router). The design for a smartphone application with client system connecting the DB and the lifebox manager is currently under development.
SHIN-BEOM CHOI,장윤석,최재붕,김영진,MYUNG-JO JHUNG,YOUNG-HWAN CHOI 한국원자력학회 2010 Nuclear Engineering and Technology Vol.42 No.5
Recently, efficient operation and practical management of power plants have become important issues in the nuclearindustry. In particular, typical aging parameters such as stress and cumulative usage factor should be determined accuratelyfor continued operation of a nuclear power plant beyond design life. However, most of the major components have beendesigned via conservative codes based on a 2-D concept, which do not take into account exact boundary conditions andasymmetric geometries. The present paper aims to suggest an effective fatigue evaluation methodology that uses a prototypeof the integrated model and its transfer functions. The validity of the integrated 3-D Finite Element (FE) model was provenby comparing the analysis results of individual FE models. Also, mechanical and thermal transfer functions, known asGreen’s functions, were developed for the integrated model with the standard step input. Finally, the stresses estimated fromthe transfer functions were compared with those obtained from detailed 3-D FE analyses results at critical locations of themajor components. The usefulness of the proposed fatigue evaluation methodology can be maximized by combining it withan on-line monitoring system, and this combination, will enhance the continued operations of old nuclear power plants
다공형상이 존재하는 가압기의 피로수명평가 및 응력분류선 유효성 분석
최신범(S.B. Choi),박영재(Y.J. Park),장윤석(Y.S. Chang),최재붕(J.B. Choi),김영진(Y.J. Kim),이진호(J.H. Lee),정해동(H.D. Jeong),설광원(K.W. Seul) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
The present research deals with stress analyses and fatigue life evaluation of a new complex pressurizer that includes perforated parts due to various piping and subcomponents. At first, preliminary two- and three-dimensional finite element analyses were carried out to assess the feasibility of an effective elastic modulus. Then, the appropriateness of stress classification line prescribed in ASME Sec. Ⅲ & Ⅷ and WRC Bulletin 429 as non-mandatory appendices was reviewed. Finally, after categorizing stress components, the stress intensities and cumulative usage factors at critical points of pressurizer were calculated through main analyses and compared with corresponding allowable design criteria in ASME code.
최송천(Song-Chun Choi),하제창(Je-Chang Ha),이미해(Mee-Hae Lee),조영도(Young-Do Jo),장윤석(Yoon-Suk Chang),최신범(Shin-Beom Choi),최재붕(Jae-Boong Choi) 한국비파괴검사학회 2009 한국비파괴검사학회지 Vol.29 No.2
고유가 및 에너지 문제 해결대책의 하나로 고부가가치 산업인 액화천연가스(LNG) 플랜트 건설시장에 대한 세계적 관심이 증대되고 있다. 본 논문은 선진국의 기술독점에 대응하기 위해 추진중인 우리나라의 위험도평가 기술개발 방안을 소개하기 위한 것이다. 먼저 위험도평가 기술을 정의한 후 국내외 기술의 특징 및 수준을 분석하였다. 기술분석 결과를 토대로 위험도평가 프로그램, 비파괴진단 신뢰도평가 기술, 안전기준 통합클래스 개발이라는 핵심 요소를 도출하였다. 이는 정보 기반의 융합기술로써, 다양한 설비 검사 및 진단분야의 데이터베이스와 인공지능형 최적화 기법을 탑재한 비파괴평가 시스템과 연계하여 LNG 플랜트 모듈화 및 효율성 개선을 위해 활용될 수 있다. As one of promising solutions to overcome high oil price and energy crisis, the construction market of high value-added LNG plants is spotlighted world widely. The purpose of this manuscript is to introduce domestic activities to develop risk assessment technology against overseas monopolization. After analyzing relevant specific features and their technical levels, risk assessment program, non-destructive reliability evaluation strategy and safety criteria unification class are derived as core technologies. These IT-based convergence technologies can be used for enhancement of LNG plant efficiency, in which the modular parts are related to a system with artificial optimized algorithms as well as diverse databases of facility inspection and diagnosis fields.