• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.9
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• pp.1001-1008
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• 2015

This paper introduces the architecture of the power supply in order to achieve the safety integrity target for power supply which is a part of safety related system. The integrity level for safety is set 4 and according to the IEC 62425 which is standard for railway application the architecture design is conducted and process for design is developed. The procedure for design consists with 6 steps. The architecture of power supply that is able to keep the safety integrity against of failure of power supply is derived through the analysis and it is suggested that the power supply adopted the result in this paper is suitable to apply in safety system. Also, the failure frequency that is a quantitative value for the power supply is proposed.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.64-69
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• 2012

The concept of SIL is applied in the most of all standards relating to functional system safety. However there are problems for the people to apply SIL to their plants. as these standards don't include sufficient informations. In this regards, this paper will suggest the direction of SIL application and concept based on IEC 61508 and IEC 61511. A Safety Integrity Level(SIL) is the discrete level(one out of possible fours), corresponding to a range of the probability of an E/E/PE (Electric/Electrical/Programmable Electrical) safety-related system satisfactorily performing the specific safety functions under all the stated conditions within a stated period of time. SIL can be divided into the target SIL(or required SIL) and the result SIL. The target SIL is determined by the risk analysis at the analysis phase of safety lifecycle and the result SIL is calculated during SIL verification at the realization phase of safety lifecycle. The target SIL is determined by the risk analysis like LOPA(Layer Of Protection Analysis), Risk Graph, Risk Matrix and the result SIL is calculated by HFT(Hardware Fault Tolerance), SFF(Safe Failure Fraction) and PFDavg(average Probability of dangerous Failure on Demand). SIL is applied to various areas such as process safety, machinery(road vehicles, railway application, rotating equipment, etc), nuclear sector which functional safety is applied. The functional safety is the part of the overall safety relating to the EUC and the EUC control system that depends on the correct functioning of the E/E/PE safety-related systems and other risk reduction measures. SIL is applied only to the functional safety of SIS(Safety Instrumented System) in safety. EUC is the abbreviation of Equipment Under Control and is the equipment, machinery, apparatus or plant used for manufacturing, process, transportation, medical or other activities.

• Journal of Aerospace System Engineering
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• v.6 no.2
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• pp.28-34
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• 2012

Structural integrity evaluation is important item in the aircraft certification. Recently, it is designed for limit load, material weakness about fatigue and corrosion, damage by bird strike in flight to evaluate structural integrity of aircraft. And static/fatigue analysis are performed to secure structural integrity, it was verified by static and fatigue tests. To evaluate the structural integrity of small aircraft tail, structural integrity was calculated by the finite element analysis. In the present study, finite element analysis are performed to pick out load cases in flight occurrence, and secure margin of safety to evaluate structural integrity of KC-100 tail unit. The proprieties of finite element analysis results are compared with the static structure test results. The estimation process of structural integrity for small aircraft tail may help the design.

• Journal of Mechanical Science and Technology
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• v.17 no.7
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• pp.947-957
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• 2003

The pressure tube is a major component of the CANDU reactor, which supports nuclear fuel bundle. In order to complete the integrity evaluation of pressure tube, expert knowledge, iterative calculation procedures and a lot of input data are required. More over, results of integrity assessment may be different according to the evaluation method. For this reason, an integrity evaluation system, which provides efficient way of evaluation with the help of attached database, was developed. The present system was built on the basis of 3D FEM results, ASME Sec. XI, and Fitness For Service Guidelines for CANDU pressure tubes issued by the AECL (Atomic Energy Canada Limited). The present system also covers the delayed hydride cracking and the blister evaluation, which are the characteristics of pressure tube integrity evaluation. In order to verify the present system, several case studies have been performed and the results were compared with those from AECL. A good agreement was observed between those two results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4863-4870
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• 2015

Currently, as a priority to secure the safety of the railway signalling system, verification for satisfy of the safety integrity requirements(SIR) is required to the essential elements. Safety Integrity Requirements(SIR) verification is performed based on the system safety analysis. But the probability of securing basic data for system safety analysis significantly dropped because there is no experience yet performed in the country. Therefore we are had to rely on a qualitative analysis. There are methods such as qualitative risk analysis matrix, and risk graphs. The qualitative analysis is wide, the width of the accident. However, the reliability of the result is significantly less has a disadvantage. Therefore, it should be parallel quantitative safety analysis of the system/products in order to compensate for the disadvantages of the qualitative analysis. This paper presents a quantitative safety analysis method to overcome the disadvantages of the qualitative analysis. And through a result, highly reliable Safety Integrity Requirements(SIR) verification measures proposed. Verification results, the dangerous failure incidence for vital data processing device was calculated to be $1.172279{\times}10^{-9}$. The result was verified to exceed the required safety integrity targets more.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.8-13
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• 2003

This study proposes integrity evaluation method of weld zone in rails using high precision distance amplitude characteristics curve(DACC) and ultrasonic signals. For these purposes, the ultrasonic signals for defects(porosity and crack) of weld zone in rails are acquired in the type of time series data and echo strength. 6 lines in the DACC indicated damage evaluation standard of weld zone in rails. The aquired ultrasonic signals agree fairly well with the mesured results of reference block and sensitivity block(defect location, beam propagation distance, echo strength, etc). The proposed high precision DACC in this study can be used for integrity evaluation of weld zone in rails.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.248-251
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• 2014

As more vehicles become equipped with advanced electronic control systems, more consideration is needed with regards to automotive safety issues related to the effects of electromagnetic waves. Unwanted electromagnetic waves from the antenna, electricity and other electronic devices cause the performance and safety problem of automotive components. In general, Power Integrity and Signal Integrity analysis have been widely used, but these analyses have stayed PCB level. PCB base analysis is different from radiated emission TEST condition so its results are used just for reference. This paper proposes EMC optimization technology using module level 3-dimensional radiation simulation process closed to fundamental test conditions. If module level EMC analysis, which is proposed in this study, is applied to all automotive electronics systems, unexpected EMC noise will be prevented.

• Nuclear Engineering and Technology
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• v.32 no.1
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• pp.67-76
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• 2000

Significant wall thinning due to flow accelerated corrosion(FAC）was recently reported in main feedwater pipes in 3 Korean pressurized water reactor(PWR) plants. The main feedwater pipes in one plant were repaired using overlay weld method at the outside of pipe, while those in 2 other plants were replaced with new pipes. In this study, the effect of the wall thinning in the main feedwater pipes on piping integrity was evaluated using finite element method. Especially, the effects of both the overlay weld repair and the stress concentration in notch-type thinned area on the piping integrity were investigated. The results are as follows : (1) The piping load carrying capacity may significantly decrease due to FAC. In special, the load carrying capacity of the main feedwater pipe was reduced by about 40% during about 140 months operation in Korean PWR plants. (2) By performing overlay weld repair at the outside of pipe, the piping load carrying capacity can increase and the stress concentration level in the thinned area can be reduced.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.647-654
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• 2007

Postulation of flaws, one of the most important areas in RPV integrity assessment, significantly affects the results. In the present work, several parameters, such as orientation, underclad vs. surface cracking, crack depth and shape, etc., are postulated and parametric studies are performed to investigate the influence of the flaw parameters on the structural integrity assessment of the reactor pressure vessel during pressurized thermal shock. The influence of individual parameters describing the crack is evaluated based on sensitivity study results.

• Proceedings of the Safety Management and Science Conference
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• 2008.04a
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• pp.185-196
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• 2008

The objective of this study is to evaluate the mechanical behaviors and structural integrity of the weldment of high strength steel by using an acoustic emission (AE) techniques. Simple tension and AE tests were conducted against the 3 kind of welding test specimens. In order to analysis the effectiveness of weldability, joinability and structural integrity, we used K-means clustering method as a unsupervised learning pattern recognition algorithm for obtained multivariate AE main data sets, such as AE counts, energy, amplitude, hits, risetime, duration, counts to peak and rms signals. Through the experimental results, the effectiveness of the proposed method is discussed.