• Journal of the Society of Naval Architects of Korea
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• v.33 no.2
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• pp.96-110
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• 1996

Aging ships can suffer structural damage due to corrosion, fatigue crack etc., and possibility of catastrophic failure of seriously damaged ships is very high. To reduce the risk of loss of ships due to hull collapse, it is essential to evaluate ultimate hull strength of aging ships taking into account various uncertainties associated with structural damages. In this paper, ultimate strength-based reliability analysis of ship structures considering wear of structural members due to corrosion is described. A corrosion rate estimate model for structural members is introduced. An ultimate limit state function of a ship hull is formulated taking into account corrosion effects. The model is applied to an existing oil tanker, and reliability index associated with hull collapse is calculated by using the second-order reliability method (SORM). Discussions on structure safety of corroded ships are made.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4398-4404
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• 2015

Stainless steel sheets are widely used as the structural material for dynamic machine structures, These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding, For fatigue design of gas welded joints such as various type joint. It is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of gas welded joints. Thus in this paper, ${\Delta}P-N_f$ curves were obtained by fatigue tests. and, ${\Delta}P-N_f$ curves were rearranged in the ${\Delta}{\sigma}-N_f$ relation with the hot spot stresses at the gas welded joints. Using these results, the accelerated life test(ALT) is conducted. From the experiment results, an life prediction model is derived and factors are estimated. So it is intended to obtain the useful information for the fatigue lifetime of welded joints and data analysis by statistic reliability method, to save time and cost, and to develop optimum accelerated life prediction plans.

• Journal of Aerospace System Engineering
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• v.12 no.4
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• pp.98-105
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• 2018

The satellite is exposed to various launch environments such as random vibrations and shock. Accordingly, structural design of electronic equipment mounted on satellite must meet reliability requirements at the box level. In addition, it is essential to secure the reliability of the solder joint applied to electronic equipment. In this paper, we performed a modal and quasi-static analysis for the purpose of satisfaction of the design requirements of the CCB (Camera Controller Box) present on the 500 kg-class compact advanced satellite (CAS500). In addition, structural safety of electronic components was verified by the Steinberg's method and random equivalent static analysis.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.1 s.38
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• pp.63-72
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• 2006

Mobile products, such as cellular phones, PDA and notebook, are subjected to many different mechanical loads, which include bending, twisting, impact shock and vibration. In this study, a cyclic bending test of the BGA package was performed to evaluate the fatigue life. Special bending tester, which was suitable for electronic package, was developed using an electromagnetic actuator. A nonlinear finite element model was used to simulate the mechanical bending deformation of solder joint in BGA packages. The fatigue life of lead-free (95.5Sn4.0Ag0.5Cu) solder joints was compared with that of lead-contained (63Sn37Pb). When the applied load to the specimen is small, the lead-free solder has longer fatigue life than lead-contained solder. The fatigue crack is initialized at the exterior solder joints and is propagated into the inner solder joints.

• Korean Security Journal
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• no.60
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• pp.283-302
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• 2019

This study was conducted to provide the basic data for improving the working environment and welfare level of the security guard by identifying the primary effects of stress response on fatigue with emotional labor and identifying the adjustment effects with coping strategy. The data were collected from 214 security personnel using questionnaire and the statistical tests of correlation, heavy return analysis and hierarchical return analysis using the SPSS 18.0 statistics program were used to reach the conclusion that: First, it has been shown that the emotional labor of a security guard affects fatigue Second, the effects of emotional labor on fatigue of a security guard have been shown to have the effect of coping strategy. Based on the above studies, it was concluded that the emotional labor of a security guard was affected by fatigue and could be controlled by a stress coping strategy. Therefore, it is believed that there is a need to seek an autonomous corporate culture based on the organization's performance by changing the management system for employees at the organizational level so that security guards can use an active way of coping.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.937-940
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• 2005

인터넷 기반 자원 공유 시스템은 네트워크에 연결된 피어의 자원을 이용하여 고성능의 컴퓨팅 구현을 위한 시스템이다. 인터넷 기반 자원 공유 시스템의 가변적인 환경은 피어의 등록 및 삭제가 자유로워 연산 처리에 대한 신뢰성 문제를 발생시킨다. 본 논문에서는 인터넷 기반 자원 공유 시스템의 신뢰성 향상을 위해서 이기종 시스템간의 협업 그룹을 생성하여 관리하는 협업 관리 시스템을 설계한다. 효율적인 협업 관리를 위해 이기종 피어를 관리하는 협업 그룹을 정의하고 계층 구조의 중간DB서버를 제안한다. 그리고 협업 관리 시스템에서 제공되는 협업 그룹 서비스, 디스커버리 서비스, 작업 관리 서비스를 제안한다.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2037-2039
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• 2003

원자력 발전소의 원자로보호계통(Plant Protection Systems)은 그 특성상 안전성과 신뢰성을 중시하며, 매우 엄격한 설계 요건을 요구한다. 또한 원자로 보호계통에 사용되는 데이터 통신망은 최악의 예상된 조건에서도 신뢰할 수 있는 성능을 보여야 하며, 실증 시험을 통해 확인되어야 한다. 이러한 특성을 고려하여 국산화과제로 개발 중인 원자로보호계통의 데이터 통신망은, 개방형 통신 프로토콜인 프로피버스(Profibus)를 적용하고 있다. 본 논문에서는 적용된 통신 프로토콜인 Profibus에 대한 성능 모델을 제시하고, 제시된 성능 모델을 통해 데이터통신망이 결정론적(Deterministic) 요건을 만족한 수 있는 성능 특성을 분석하고자 한다. 이를 통해 Profibus를 적용한 데이터 통신망이 요구되는 성능, 신뢰성, 독립성 및 건전성 요건을 만족하도록 하기 위한 설계 요건을 제시하고자 한다.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.4
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• pp.83-89
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• 2002

Oil ring and sound proof rubbers are very much important because the cause of oil leakage are mostly occupied by these rubbers. So good oil rings are the necessary parts of autolife expansion. The expensive selection system keeps from factory automation and most works are established manually. These study has been the basis of test equipments automatically in rubber products and DCT algorithm has been applied and the selection system is made efficiently differentiating good or poor.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.337-342
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• 2011

Medical lift column controlling the vertical position while supporting heavy eccentric load should have the high fatigue strength as well as the extremely low structural deflection and vibration in order to maintain the positioning accuracy. The lift column driven by a induction motor is generally in a three-step sliding boom structure and exhibits the time-varying stress distribution according to the up-and-down motion. This study is concerned with the numerical prediction of the fatigue strength of the lift column subject to the time-varying stress caused by the up-and-down motion. The stress variation during a motion cycle is obtained by finite element analysis and the fatigue life is predicted making use of Palmgren-miner's rule and S-N curves. In order to secure the numerical analysis reliability, a 3-D FEM, model in which the detailed lift column structure and the fitting parts are fully considered, is generated and the interfaces between lift column and pads are treated by the contact condition.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.89-98
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• 2017

The offshore plant structure has been transported to the site by barge because it is hard to manufacture in site. When the structure was transported on the sea, offshore plant structures and connection were experienced repetitive submarine load. For this reason, it was known for that the axial force of high-strength bolted connection was declined. Therefore, in this study, high-strength bolted connection was evaluated the shear fatigue performance under longtime fatigue load during marine transport. The experimental variables were selected intial axial force, surface type, and bolt type because they ar important factors in the change of axial force of bolts. As a experimental results of considering various variables, the variation of axial force showed within 1%. Therefore, the high-strength bolted connection was verified structural safety under longtime fatigue load.