• Journal of the Korean Institute of Gas
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• v.24 no.4
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• pp.84-92
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• 2020

Most facilities in chemical plants operate in environments that are outside the range of temperature and pressure that can be encountered on a daily basis, and are vulnerable to aging due to these stresses and environmental conditions. The facilities exposed to these conditions are not only likely to fail due to cumulative damage, but also lead to accidents if maintenance and replacement are not performed.Recommendation guidelines called risk-based inspection are widely used around the world-wide. However, limits exist for facilities that have already elapsed for a certain. As a result of the survey on the aging of Ulsan industrial complex in Korea, which carries out proper inspection, many of the facilities have been used for 20 years. Also, most of the facilities where the accident occurred have been in operation for more than 20 years. Therefore, this study suggested criteria for classifying devices that have exceeded a certain period of use as obsolete facilities. In addition, quantitative risk assessment was conducted. The safety investment method using the cost-benefit analysis method was proposed in order to calculate the loss cost and reduce the risk by expressing the risks of the corresponding aged facility as an Economic index. By utilizing the method of cost-benefit analysis of old facilities using the quantitative risk assessment presented in this study, it can be expected to improve the performance and life of old facilities, improve production efficiency and reliability of the system of facilities, change the recognition of safety management costs, increase employee stability, and reduce loss costs.

• Industrial Engineering and Management Systems
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• v.9 no.1
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• pp.54-59
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• 2010

A two-plan sampling system is proposed for a failure-censored life testing when the lifetime follows a Weibull distribution with known shape parameter. The proposed sampling system is based on a switching rule, for switching between the tightened and the normal inspection levels when lots are submitted for inspection in the order of production or in some other systematic way. The design parameters of the proposed sampling system are determined by the two-point approach considering the producer's risks and the consumer's at the specified acceptable reliability level and the lot tolerance reliability level, respectively. It has been observed that the proposed system requires only a single failure for the observation.

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.66-72
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• 2002

During the last ten years, effort has been made for reducing maintenance cost for aged equipments and ensuring safety, efficiency and profitability of petrochemical and refinery plants. Hence, it was required to develop advanced methods which meet this need. RBI(Risk Based Inspection) methodology is one of the most promising technology satisfying the requirements in the field of integrity management. In this study, a qualitative assessment algorithm for RBI based on the API 581 code was reconstructed for developing an RBI software. The user-friendly realRBI software is developed with a module for evaluating qualitative risk category using the potential consequence factor and the likelihood factor.

• Journal of Korean Society for Quality Management
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• v.30 no.1
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• pp.74-96
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• 2002

The objectives of this study is to suggest the rectifying sampling inspection plan considering quality cost. Limiting quality level(LQL) plans(also called LTPD plans) and outgoing quality(OQ) plans are considered. The Hald's linear cost model is discussed with and without a beta prior for the distribution of the fraction of nonconforming items in a lot. It is assumed that the sampling inspection is error free. We consider the design of reliability acceptance sampling plan (RASP) for failure rate level qualification at selected confidence level. The lifetime distribution of products is assumed to be exponential. MIL-STD-690C and K C 6032 standards provide this procedures. But these procedures have some questions to apply in the field. The cost of test and confidence level(1-$\beta$ risk) are the problem between supplier and user. So, we suggest that the optimal life test sampling inspection plans using simple linear cost model considering product cost, capability of environment chamber, environmental test cost, and etc. Especially, we consider a reliability of lots that contain some nonconforming items. In this case we assumed that a nonconforming item fail after environmental life test. Finally, we develope the algorithm of the optimal sampling inspection plan based on minimum costs for rectifying inspection and RASP. And computer application programs are developed So, it is shown how the desired sampling plan can be easily found.

• The Journal of the Korean dental association
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• v.52 no.8
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• pp.456-463
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• 2014

Caries Management by Risk Assessment (CAMBRA), published by California Dental Association in 2003, is a customized caries care system that classifies individuals' caries risk into 4 risk groups based on objective evidences and provides chemical treatments targeted for each caries risk level. However, this system was not only developed but also optimized for situation in the United States, resulting into many limitations to be used in Korea, and thus Korean CAMBRA (K-CAMBRA) that considers the clinical situation in Korea needs to be developed. K-CAMBRA includes various techniques that are newly developed in order to overcome the limitations. First, Q-ray, a new optical technology, is utilized in order to avoid the subjectivity of visual inspection during assessment of disease indicators and risk factors. Moreover, Cariview? that reflects the paradigm shift in cariology as a new form of caries assessment kit is used. In addition, considering the situation in Korea, where it is impossible to use high concentration fluoride product, Oral pack with a customized tray is added to increase the contact time of chemical substance. CAMBRA is believed to be the key clinical tool that overcomes the limitations of the paradigm of the conventional restoration-based surgical model of dentistry. Furthermore, it can be expected that Korean dentists can act as oral physicians who are able to control and care individuals' caries risk rather than operative experts who only care about the outcome of caries.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.4 no.5
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• pp.11-14
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• 1981

This study intends to decide the economic sample size based on the cost of sampling Inspection for destructive testing. The marginal percent defective is used as the lot tolerance percent defective (LTPD), and the Newton's iterative method is adopted to calculate the optimum sample size(n), given by the consumer's risk($\beta$ - risk) and the acceptance number(c).

• Journal of the Korea Society of Computer and Information
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• v.28 no.11
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• pp.21-28
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• 2023

In manufacturing companies that focus on small-scale production of multiple product varieties, defective products are manually selected by workers rather than relying on automated inspection. Consequently, there is a higher risk of incorrect sorting due to variations in selection criteria based on the workers' experience and expertise, without consistent standards. Moreover, for non-standardized flexible objects with varying sizes and shapes, there can be even greater deviations in the selection criteria. To address these issues, this paper designs a quality inspection system using artificial intelligence-based unsupervised learning methods and conducts research by experimenting with accuracy using a dataset obtained from real manufacturing environments.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.144.2-144.2
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• 2005

• 한국가스학회:학술대회논문집
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• 2006.11a
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• pp.43-48
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• 2006

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2001.11a
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• pp.337-342
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• 2001

최근 국내외에서 정유$\cdot$석유화학 등의 공정 플랜트의 검사, 진단, 관리 및 보존공학(maintenance engineering)에서 관심을 끌고 있는 주제 중 하나는 RBI (risk based inspection) 기법이다. 또한 이 기법에 대한 관심은 화력발전 플랜트, 가스배관 분야의 관리에서도 마찬가지이다.(중략)