• Title/Summary/Keyword: reliability and safety

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A Study on the Evaluation Methods from Probability Computation of Bridge (교량의 과하중 확률계산을 통한 상태평가 등급 산정방법에 대한 연구)

  • Kim, Doo-Hwan;Yoo, Chang-Uk
    • Journal of the Korean Society of Safety
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    • v.24 no.4
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    • pp.53-58
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    • 2009
  • The importance of process for repair and reinforcement of the bridge is increasing because of the lack of the fatigue load and stress, a lowering of the bridge load carrying capacity owing to impact and oscillation, deterioration on cultivation periods of the bridge, etc. Typically the experimenter values the bridge load carrying capacity by the real rating factor and response modification factor in bridge load rating through static load test and dynamic load test. But the error occurred in reliability of response modification factor in bridge load rating according to experience of experimenter. so tests of connecting probability theory and valuation of the bridge recently. The study is to compute the real load carrying capacity of the bridge and the rating factor and response modification factor on grade of the bridge, and calculate the probability of over-loaded truck load from Weigh In Motion(WIM) Data in FORTRAN programming applying to Monte-Carlo Simulation. At the result of this study, it is acquired that the new grade is computed for the probability of over-loaded truck load and surface inspection. The A grade is over 1.95, B grade is $1.55{\sim}1.94$, C grade is $1.26{\sim}1.54$, D grade is $1.14{\sim}1.25$, E grade is under 1.13 of rating factor, respectively.

Comparisons of Seafarers' Perception of Maritime and Onshore Traffic Conditions

  • Park, Deuk-Jin;Kim, Hong-Tae;Yang, Hyeong-Sun;Yim, Jeong-Bin
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.3
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    • pp.320-327
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    • 2019
  • The purpose of this paper is to compare seafarers' behavior according to traffic conditions of a road and an onshore locations. Behaviors are classified into three categories: Skill-, Rule- and knowledge-based mode. Experimental data were collected using the questionnaires for navigators, working in a merchant ship. To compare the behaviors, we used the four analysis method; the degree of frequency, reliability test, correlation and linear regression. As a result of the study, it was found that Skill-based behavior shows more higher in the road traffic than the maritime traffic, and rule-based behavior shows more higher in the maritime traffic than the road traffic. Also, the behavior in the navigation situation showed statistical significance. Especially, in the case of Rule-based behavior, a high correlation between road and maritime was found. This study can be expected to apply to complementary system utilization between error management system of onshore and maritime traffic.

Factors Affecting Employee Performance: A Case Study of Railway Maintenance and Engineering Organizations in Thailand

  • POLANANT, Kanut;ROJNIRUTTIKUL, Nuttawut
    • The Journal of Asian Finance, Economics and Business
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    • v.9 no.9
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    • pp.271-281
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    • 2022
  • The objectives of the research are to study the effects of emotional intelligence (EI), reward management (RM), and occupational health and safety (OHS), on employee performance (EP) within a Thai motor service and repair firm. Starting in January 2022 through the end of March 2022, the researchers used simple random sampling techniques to select 88 employees for the case study. The research instrument was a questionnaire with an IOC value between 0.67-1.00 and a reliability value α of 0.78. Survey participants were asked to contribute their opinions to a five-level opinion survey which was hosted on Google Forms. Descriptive statistics analysis (mean and standard deviation) and multiple linear regression analysis were done using SPSS for Windows version 21. The results showed that employee opinions concerning EI, RM, OHS, and EP were at a high level, with the three hypotheses testing showing statistical significance (p ≤ 0.01). The decision coefficients (R2) all revealed relationship strength with RM = 0.861, OHS = 0.853, and EI = 0.731.

Development of a Neural Network Expert System for Safety Analysis of Structures Adjacent to Tunnel Excavation Sites Focused on Development and Reliability Evaluation of Expert System (터널굴착 현장에 인접한 지상구조물의 안전성 평가용 전문가 시스템의 개발 (1) -전문가 시스템 개발 및 신뢰성 검증을 중심으로)

  • 배규진;신휴성
    • Geotechnical Engineering
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    • v.14 no.2
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    • pp.107-126
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    • 1998
  • Ground settlements induced by tunnel excavation cause the foundations of the neighboring building structures to deform. An expert system called NESASS( Neural network Expert System for Adjacent Structure Safety analysis) was developed to analyze the structural safety of such building structures. NESASS predicts the trend of ground settlements resulting from tunnel excavation and carries out a safety analysis for building structures on the basis of the predicted ground settlements. Using neural network technique. the NESASS learns the database consisting of the measured ground settlements collected from numerous actual fields and infers a settlement trend at the field of interest. The NESASS calculates the magnitudes of angular distortion, deflection ratio, and differential settlement of the structure. and in turn, determines the safety of the structure. In addition, the NESASS predicts the patterns of cracks to be formed in the structure, using Dulacska model for crack evaluation. In this study, the ground settlements measured from Seoul subway construction sites were collected and classified with respect to the major factors influencing ground settlement. Subsequently, a database of ground settlement due to tunnel excavation was built. A parametric study was performed to select the optimal neural network model for the database. A comparison of the ground settlement predicted by the NESASS with the measured ones indicates that the NESASS leads to reasonable predictions. The results of confidence evaluation for safety evaluation system of the NESASS are presented in this paper.

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The Effect of Convenience Store Dessert on Consumers Value and Satisfaction

  • CHA, Seong-Soo;LEE, Su-Han
    • The Journal of Asian Finance, Economics and Business
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    • v.7 no.3
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    • pp.191-199
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    • 2020
  • This study aims to investigate what selection attributes of customer value are more crucial when consumers choose the dessert at convenience store, which is the fastest growing retail format in Korea recently. Factors considered to be important when customers buy dessert, such as economics, diversity, convenience, and safety were examined and also relationship between customer value and satisfaction was analyzed. The survey was conducted through online (including SNS) from April 6, 2019 to April 30, 2019. A total of 303 questionnaires were used for empirical analysis. Factor analysis was performed to verify the validity and reliability of the measured variables. And the structural equation model (SEM) was used as a statistical method for hypothesis testing. As a result, factors as 'diversity', 'safety' were revealed to significantly affect hedonic customer value, while 'convenience' was shown to affect utilitarian customer value significantly. In addition, the path that customer value leads to satisfaction was also found to be significant. The result of the study suggests that selection attributes of convenience store dessert and providing meaningful implications of related hedonic and utilitarian values when customers purchase dessert at convenience store. This study provided practical implications for managers of the fiercely competitive dessert industry.

Topological optimization procedure considering nonlinear material behavior for reinforced concrete designs

  • Franca, Marcela Bruna Braga;Greco, Marcelo;Lanes, Ricardo Morais;Almeida, Valerio Silva
    • Computers and Concrete
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    • v.17 no.1
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    • pp.141-156
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    • 2016
  • The search for new structural systems capable of associating performance and safety requires deeper knowledge regarding the mechanical behavior of structures subject to different loading conditions. The Strut-and-Tie Model is commonly used to structurally designing some reinforced concrete elements and for the regions where geometrical modifications and stress concentrations are observed, called "regions D". This method allows a better structural behavior representation for strength mechanisms in the concrete structures. Nonetheless, the topological model choice depends on the designer's experience regarding compatibility between internal flux of loads, geometry and boundary/initial conditions. Thus, there is some difficulty in its applications, once the model conception presents some uncertainty. In this context, the present work aims to apply the Strut-and-Tie Model to nonlinear structural elements together with a topological optimization method. The topological optimization method adopted considers the progressive stiffness reduction of finite elements with low stress values. The analyses performed could help the structural designer to better understand structural conceptions, guaranteeing the safety and the reliability in the solution of complex problems involving structural concrete.

A Study on the Role of Vessel Traffic Service System (해상교감관별 시스템의 지리적 후문에 관한 연구)

  • 이학선
    • Journal of the Korean Institute of Navigation
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    • v.20 no.3
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    • pp.43-63
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    • 1996
  • The purpose of this study is to find out what is the functional role of VTS in order to get the people concerned with marine traffic/transportation understand about VTS. VTS could be described as the essential risk management system in both cost effective on cost-benefit analysis and the sea space or time management at port, coastal environment. The important role of the VTS are those functions such as the decision making infrastructure, the passive/active safety measures at sea. VTS could not control/regulate marine traffic as strong as ATC(Air Traffic Control) owing to the marine traffic characters. However, the right and responsibility of VTS finally are belong to the master, pilot and mariners. For the benefit of the electronic technology development, VTS system also cloud be upgraded to communication system from information system. In connection with these system upgrading, the right and responsibility of VTS/staff should be supported by domestic legal system. The followings are presented for VTS to be effective. First, the cooperation and understanding of VTS between the peoples concerned with marine traffic/transportation are essential. Because they are all data supplier and also information consumers. Second, VTS staff/regulator should be selected, educated, trained accordingly as per their career, ability, quality, qualification, certification and etc. Third, the port reliability from VTS users depends on the factors such as economic interests, safety and effectiveness/efficiency of VTS.

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Design of Acceptance Control Charts According to the Process Independence, Data Weighting Scheme, Subgrouping, and Use of Charts (프로세스의 독립성, 데이터 가중치 체계, 부분군 형성과 관리도 용도에 따른 합격판정 관리도의 설계)

  • Choi, Sung-Woon
    • Journal of the Korea Safety Management & Science
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    • v.12 no.3
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    • pp.257-262
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    • 2010
  • The study investigates the various Acceptance Control Charts (ACCs) based on the factors that include process independence, data weighting scheme, subgrouping, and use of control charts. USL - LSL > $6{\sigma}$ that used in the good condition processes in the ACCs are designed by considering user's perspective, producer's perspective and both perspectives. ACCs developed from the research is efficiently applied by using the simple control limit unified with APL (Acceptable Process Level), RLP (Rejectable Process Level), Type I Error $\alpha$, and Type II Error $\beta$. Sampling interval of subgroup examines i.i.d. (Identically and Independent Distributed) or auto-correlated processes. Three types of weight schemes according to the reliability of data include Shewhart, Moving Average(MA) and Exponentially Weighted Moving Average (EWMA) which are considered when designing ACCs. Two types of control charts by the purpose of improvement are also presented. Overall, $\alpha$, $\beta$ and APL for nonconforming proportion and RPL of claim proportion can be designed by practioners who emphasize productivity and claim defense cost.

A Study on Ways to Improve Participation in Vocational Competency Development Training (직업능력개발훈련 참여도 향상을 위한 방안 연구)

  • Kim, Tae-Bok;Kim, Kwang-Soo
    • Journal of the Korea Safety Management & Science
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    • v.23 no.2
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    • pp.9-17
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    • 2021
  • As interest in vocational competency development projects increases, support is increasing. In this study, in order to study ways to improve participation in vocational competency development training, related factors are selected and the main factors influencing them are derived. The main factors were influencing factors were identified and ways to improve participation rate of vocational competency development were studied. Variables were selected through prior research, and data were collected and analyzed through in-depth group interviews. Based on factor analysis and reliability analysis, as a result of confirming the factors that influence the plan for improving participation in vocational competency development training by applying the backward stage selection (condition) method of logistic regression analysis, the case of respect for minorities in the 7-point Likert scale The closer to 7 was, the higher the probability of being classified as having never participated, and the other factors except minority respect, Likert scale closer to 7 indicates higher probability of bening classified as having never participated, except for the minority respect factor. Therefore, it was confirmed that lowering the scale of the factor of respect for minority, which is job satisfaction, and increasing the factors of individual characteristics such as annual salary and organizational commitment, training system for job satisfaction, and quality assurance have effects on improving participation rates in vocational competency development training.

Statistical Methodologies for Scaling Factor Implementation: Part 1. Overview of Current Scaling Factor Method for Radioactive Waste Characterization

  • Kim, Tae-Hyeong;Park, Junghwan;Lee, Jeongmook;Kim, Junhyuck;Kim, Jong-Yun;Lim, Sang Ho
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.18 no.4
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    • pp.517-536
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    • 2020
  • The radionuclide inventory in radioactive waste from nuclear power plants should be determined to secure the safety of final repositories. As an alternative to time-consuming, labor-intensive, and destructive radiochemical analysis, the indirect scaling factor (SF) method has been used to determine the concentrations of difficult-to-measure radionuclides. Despite its long history, the original SF methodology remains almost unchanged and now needs to be improved for advanced SF implementation. Intense public attention and interest have been strongly directed to the reliability of the procedures and data regarding repository safety since the first operation of the low- and intermediate-level radioactive waste disposal facility in Gyeongju, Korea. In this review, statistical methodologies for SF implementation are described and evaluated to achieve reasonable and advanced decision-making. The first part of this review begins with an overview of the current status of the scaling factor method and global experiences, including some specific statistical issues associated with SF implementation. In addition, this review aims to extend the applicability of SF to the characterization of large quantities of waste from the decommissioning of nuclear facilities.