• Title/Summary/Keyword: reliability and safety

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A Study on the Application of CUSUM Control Charts under Non-normal Process (비정규 공정에서의 누적합 관리도 적용에 관한 연구)

  • Kim, Jong-Geol;Eom, Sang-Jun;Choe, Seong-Won
    • Proceedings of the Safety Management and Science Conference
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    • 2011.11a
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    • pp.535-549
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    • 2011
  • Control chart is most widely used in SPC(Statistical Process Control), Recently it is a critical issue that the standard control chart is not suitable to non-normal process with very small percent defective. Especially, this problem causes serious errors in the reliability procurement, such as semiconductor, high-precision machining and chemical process etc. Procuring process control technique for non-normal process with very small percent defective and perturbation is becoming urgent. Control chart technique in non-normal distribution become very important issue. In this paper, we investigate on research trend of control charts under non-normal distribution with very small percent defective and perturbation, and propose some variable-transformation methods applicable to CUSUM control charts in non-normal process.

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A Study on the Development Of Standard Management System for the Work Efficiency Improvement of the Auto Part Supplier (자동차 부품업체의 업무 효율성 향상을 위한 표준관리시스템 구축에 관한 연구)

  • Lee, Hee-Nahm;Park, Je-Won
    • Journal of the Korea Safety Management & Science
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    • v.12 no.4
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    • pp.223-228
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    • 2010
  • Recently, the various information according to the company management is originated in the change of the rapid company environment. And the necessity of the administration,that is systematic and efficient toward the various document of a form, is gradually increased. At the same time, the efficient management ability of the various standard document obtained the specialized quality authentication system including the ISO/TS16949, ISO14001, quality 5 star, and etc., it maintains occupies the very important part as to the company management. This research suggests the standard business process of the auto part supplier for the efficient management of the standard document. In addition, by building and managing the standard management system will be able to expect the more efficient document management and the product reliability insurance.

Model for Process Quality Assurance When the Fraction Nonconforming is Very Small (극소불량 공정보증을 위한 모형연구)

  • Jong-Gurl Kim
    • Proceedings of the Safety Management and Science Conference
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    • 1999.11a
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    • pp.247-257
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    • 1999
  • There are several models for process quality assurance by quality system(ISO 9000), process capability analysis, acceptance control chart and so on. When a high level process capability has been achieved, it takes a long time to monitor the process shift, so it is sometimes necessary to develop a quicker monitoring system. To achieve a quicker quality assurance model for high-reliability process, this paper presents a model for process quality assurance when the fraction nonconforming is very small. We design an acceptance control chart based on variable quality characteristic and time-censored accelerated testing. The distribution of the characteristics is assumed to be normal of lognormal with a location parameter of the distribution that is a linear function of a stress. The design parameters are sample size, control limits and sample proportions allocated to low stress. These parameters are obtained under minimization of the relative variance of the MLE of location parameter subject to APL and RPL constraints.

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A Study on the Analytic Technique Combination and Evaluation of Development Process for Software Safety (S/W 안전성을 위한 분석기법 조합과 개발 프로세스 평가에 대한 연구)

  • Lee, Young-Soo;Ahn, Jin;Ha, Seung-Tea;Cho, Woo-Sik;Han, Chan-Hee
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.1468-1476
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    • 2006
  • The goal of this thesis is to support safety and reliability characteristics of software intensive critical systems. The verification method developed is innovative from current state of the art in what concerns the verification viewpoint adopted: focusing on software faults, and not, like many other approaches purely on fulfilling functional requirements. As a first step and based on a number of well defined criteria a comparison was made of available literature in the area of static non formal non probabilistic software fault removal techniques. But, None of the techniques evaluated fulfilled all criteria set in isolation. Therefore a new technique was developed based on a combination of two existing techniques: the FMEA and FTA. These two techniques complement each other very well. It is possible to integrate both techniques with commonly used techniques at system level. The resulting new technique can be shown to combine nearly all aspects of existing fault removal techniques.

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Management and operation of K-AGT test line (한국형경량전철 시험선의 관리 및 운영)

  • Han, Seok-Youn;Jun, Bong-Roong;Lee, Ho-Yong;Lee, An-Ho
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.964-967
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    • 2006
  • Korea Railroad Research Institute (the following 'KRRI') built AGT test line in Gyeong San-city, Kyongsang-bukdo province, Korea on August, 2004. This test line is exclusively used for the test of the driverless rubber-tired AGT system, and applied with research result of AGT System Development Project like vehicles, power supply, control and signaling, track and infrastructure system. The test line is available for the test of rubber tired AGT system's performance, function, safety. In this paper, we described the operation system of test line for the test of performance, safety, reliability, and also system operation in emergency. Finally we present the operation result of test line.

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Creep Rupture Life Prediction of High Temperature HRSG Tubes (고온 폐열회수장치 튜브의 크리프 파단특성 평가)

  • Kim, Woo Joong;Kim, Jae Hoon;Jang, Jung Cheol;Kim, Beom Soo;Lee, Gi-Chun
    • Journal of the Korean Society of Safety
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    • v.28 no.3
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    • pp.6-10
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    • 2013
  • The Heat Recovery Steam Generator(HRSG) is a device recycling the exhaust gas of gas turbine in combined power and chemical plants. Since service temperatures was very high, the damage of HRSG tubes intensively occurred in superheater and reheater. The aim of this paper is to determine life and hardness relationship that addresses creep-rupture test and creep-interrupt test in modified 9Cr-1Mo steel. The measured life that consists of function of hardness was found to constant tendency.

A Study of Technology Trends for Effective Process Control under Non-Normal Distribution (비정규분포하에서의 효과적 공정관리를 위한 기술체계동향 연구)

  • Kim, Jong-Gurl;Um, Sang-Joon;Kim, Young-Sub;Ko, Jae-Kyu
    • Proceedings of the Safety Management and Science Conference
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    • 2008.11a
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    • pp.599-610
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    • 2008
  • It is an important and urgent issue to improve process capability in quality control. Process capability refers to the uniformity of the process. The variability in the process is a measure of the uniformity of output. A simple, quantitative way to express process capability, the degree of variability from target in specification is defined by process capability index(PCI). Almost process capability indices are defined under normal distribution. However, these indices can not be applied to the process of non-normal distribution including reliability. We investigate current research on the process of non-normal distribution, and advanced method and technology for developing more reliable and efficient PCI. Finally we suggest the perspective for future study.

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Traffic Accident Analysis using Doppler Effect of the Horn (경적음의 도플러 효과를 이용한 교통사고분석)

  • Choi, Youngsoo;Kim, Jonghyuk;Yun, Yongmun;Park, Jongchan;Park, Hasun
    • Journal of Auto-vehicle Safety Association
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    • v.12 no.4
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    • pp.70-77
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    • 2020
  • In this study, we estimate the vehicle speed by analyzing the acoustic data recorded in a single microphone of a surveillance camera. The frequency analysis of the acoustic data corrects the Doppler effect, which is a characteristic of the moving sound source, and reflects the geometric relationship according to the location of the sound source and the microphone on the two-dimensional plane. The acoustic data is selected from the horn sound that is mainly observed in an urgent situation among various sound sources that may occur in a traffic accident, and the characteristics of the monotone source are considered. We verified the reliability of the proposed method by time domain acoustic analysis and actual vehicle evaluation. This method is effective and can be used for traffic accident analysis in the blind spot of the camera using a single microphone built into the existing surveillance camera.

A Study on the Effects of Aviation Safety Perception among College Students Majoring in Aviation Service on Major Recognition, Major Commitment, and Employment Efficacy (항공서비스전공 대학생의 항공안전 인식이 전공인식, 전공몰입, 취업효능감에 미치는 영향에 관한 연구)

  • Ha Young Kim
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.31 no.3
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    • pp.119-132
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    • 2023
  • In recent years, the competition for employment among college students has become more intense. It is also the time when strong personal beliefs and will to develop careers are required for successful employment through stable major study. Therefore, in this study, we tried to find out the effect on major attitude and employment efficacy according to the level of aviation safety perception, which is an important issue in the aviation industry. For analysis, survey is conducted targeting college students majoring in aviation service who are enrolled in universities in the metropolitan area and Chungcheong area. To verify the hypotheses of the study, demographic characteristics are identified based on questionnaires, reliability and validity of measurement items are verified, and structural equation model analysis is performed to verify the hypotheses. The analysis results are as follows. First, it is found that safety knowledge and safety consciousness, which are sub-factors of aviation safety perception of college students majoring in aviation service, have a positive (+) effect on subject recognition, learning process recognition, and career recognition of major recognition. Second, subject recognition, learning process recognition, and career recognition, which are sub-factors of major recognition, are found to have a positive effect on major commitment. Third, it is found that major commitment have a positive (+) effect on employment efficacy. Based on the research results, practical support plans and strategies for effective major study and successful employment are presented.

Establishment and Application of Failure Reporting and Corrective Action System for Korean High Speed Train (한국형 고속열차 고장정보체계 구축 및 활용)

  • Lee, Tae-Hyeong
    • 시스템엔지니어링워크숍
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    • s.4
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    • pp.81-85
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    • 2004
  • 시스템 엔지니어링은 시스템의 일생 주기동안 수행되며 고장정보체계(Failure Reporting and Corrective Action System)는 제작단계부터 수행되는 RAMS(Reliability, Availability,Manitani bility,safety)과업 중의 하나이다. 고장정보체계는 설계와 제작단계에서 생성된 고장원인을 제거하고 수정작업을 구현하기 위한 방법을 제공한다. 본 논문에서는 한국형 고속열차를 대상으로 고장정보 분석 및 관리, 신뢰도 평가를 위해 구축한 고장정보체계와 그 활용사례를 제시한다.

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