• Journal of Korea Foundry Society
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• v.41 no.6
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• pp.521-527
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• 2021

This study presents a process management method for the detection of casting defects during in high-pressure die casting based on machine learning. The model predicts the defects of the next cycle by extracting the features appearing over the previous cycles. For design of the gearbox, the proposed model detects shrinkage defects with data from three cycles in advance with 98.9% accuracy and 96.8% recall rates.

• Agrochemical news magazine
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• v.22 no.10 s.173
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• pp.6-9
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• 2001

• KIPS Transactions on Software and Data Engineering
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• v.11 no.6
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• pp.229-236
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• 2022

Based on the Internet of Things, a web system that can check the condition around the fire extinguisher, whether a fire has occurred, and an application that can receive fire notifications in real time is implemented. Minimize errors that occur during development by using software engineering to clarify the goals of the system and define the structure in detail. In addition, for IoT-based fire extinguishers, a method of reducing defects by finding product defects in the demand analysis, design, and implementation stages and analyzing the cause thereof is proposed. Through the proposed research, it is possible to secure the reliability of defect management for IoT-based smart fire extinguisher.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.397-403
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• 2001

본 논문은 시장 사용 조건에서 발생한 PC제품의 Main board 고장품이 회수 후 검토 시 정상적으로 기능하여 나타나는 NDF(No Defect Found) 판정 상황에 대한 효과적인 검토 방안을 제시한다. NDF 시료의 고장성 진위 여부를 가리기 위해 HALT(Highly Accelerated Life Test)기술을 응용한 결과 기존의 시험 검토 방법보다 높은 재현 효과를 보았다. 결함 제품의 잠재적인 취약부위를 단시간에 효과적으로 촉진하고 들춰내는 HALT 기술은 전자 제품의 NDF성 고장을 기술적으로 접근하여 개선할 수 있는 기초를 제공하는 유용한 가속 스트레스 시험 기술임이 입증되었다.

• Review of KIISC
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• v.24 no.2
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• pp.50-55
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• 2014

자동차 전장제품 활용의 급속한 증가에 대응하기 위하여 자동차 분야에서는 ISO 26262 안전설계절차를 도입하여 차량용 임베디드 시스템의 안전성을 확보하려고 노력하고 있다. ISO 26262는 자동차에서 발생 가능한 비정상상태(abnormal state)를 식별하고 그의 영향을 분석하며 전체 시스템의 안전을 검증하는 것을 목표로 하고 있다. 다양한 종류의 부품이 연동되는 복잡한 시스템의 안전 검증은 결함수목법과 고장모드영향분석법을 활용하는 위험분석법이 보편적으로 사용된다. 결함주입시험은 이러한 위험분석의 기반도구로서 안전성을 향상시키기 위하여 사용된 고장감내 기능의 동작여부 및 그에 따른 시스템의 안전성을 검증하는 목적으로 사용된다. 본 논문에서는 차량용 고신뢰성 임베디드 시스템에서 사용되는 고장감내 메카니즘들의 기능과 안전을 검증하는 방법과 사례를 소개한다. 최근의 복잡한 차량용 임베디드 시스템의 개발은 상위수준의 모델을 개발하여 지정된 위험 및 고장을 초래하는 결함을 시스템에 주입하고 그의 결과를 분석하여 안전을 검증하는 것이 일반적인 방법이다. 개발 목표 차량의 임베디드 시스템 모델을 개발하고, 식별된 결함의 결함모델을 준비한 뒤, 시스템 모델 기반 결함주입 도구를 이용하여 결함주입을 수행하는 시험방법과 그 결과에 대하여 논의한다. 하드웨어는 SystemC 하드웨어 설계언어를 이용하여 개발하고, 소프트웨어를 컴파일하여 실행화일을 확보하여 시험대상인 결함모델을 개발하고 이를 대상으로 결함주입시험에 대해 설명한다.

• The Korean Journal of Air & Space Law and Policy
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• v.30 no.1
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• pp.151-180
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• 2015

South Korea is advancing the unmanned aircraft private commercial business. Unmanned aerial vehciles industry has been developing for several years also abroad. However, unmanned aerial vehciles industry, can be an accident occurs. Accident of unmanned aerial vehciles to occur material damage and casualties. Particularly if an accident because of a defect in the unmanned aerial vehciles has occurred, it is necessary to analyze the liability for this. The defect accidents unmanned aerial vehciles has been the different manufacturing and design product is intended, whether it is important how to prove to this. This is because, unmanned aerial vehciles are designed in any intent of the original, it is impossible to victims know. So imposing a responsibility to prove the design by the manufacturer intended consumer is not fair. Moreover, the consumer, it is necessary to prove only that the product is one that normally dangerous lacked safety can be expected. This is a detailed issue of judgment of defects of unmanned aerial vehciles, the manufacturer to bear the accountability. In the case where the defect on the display of the unmanned aircraft is a problem, and if it reasonable indication, it is not appropriate to be required to prove that it was possible to prevent damage to the victim.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.672-678
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• 2020

Ogive parts of large-caliber ammunition in Korea are manufactured by the Press Nosing method, but this method has the disadvantage of requiring additional processes such as lubrication before and after the press process. This study proposes the possibility of applying the Swaging method to improve these shortcomings. A large-diameter shell body was manufactured in sub-scale and plastic working experiments using a swaging process were performed. We investigated whether plastic processing is possible up to 75 % of the diameter reduction rate that satisfies the final molding dimension, and whether the dimensions of the product produced by swaging molding are satisfactory as the hardness changes according to the diameter reduction rate and the increase in thickness. The test using the prototype confirmed that the hardness increased proportionally with the diameter reduction rate and by more than HV 335 at the reduction rate of 75 %. The material thickness variation tended to be similar to the theoretical calculated value, and the thickness increase rate was proportional to 65.4 % at the reduction rate of 75 %.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6432-6439
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• 2014

The NAUT (Non-contact Air coupled Ultrasonic Testing) technique is one of the ultrasonic testing methods that enables non-contact ultrasonic testing by compensating for the energy loss caused by the difference in acoustic impedance of air with an ultrasonic pulser receiver, PRE-AMP and high-sensitivity transducer. As the NAUT is performed in a state of steady ultrasonic transmission and reception, testing can be performed on materials of high or low temperatures or specimens with a rough surface or narrow part, which could not have been tested using the conventional contact-type testing technique. For this study, the internal defects of spot weld, which are often applied to auto parts, and CFRP parts, were tested to determine if it is practical to make the NAUT technique commercial. As the spot welded part had a high ultrasonic transmissivity, the result was shown as red. On the other hand, the part with an internal defect had a layer of air and low transmissivity, which was shown as blue. In addition, depending on the PRF (Pulse Repetition Frequency), an important factor that determines the measurement speed, the color sharpness showed differences. With the images obtained from CFRP specimens or an imaging device, it was possible to identify the shape, size and position of the internal defect within a short period of time. In this paper, it was confirmed in the above-described experiment that both internal defect detection and image processing of the defect could be possible using the NAUT technique. Moreover, it was possible to apply NAUT to the detection of internal defects in the spot welded parts or in CFRP parts, and commercialize its practical application to various fields.

• Korean Journal of Human Ecology
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• v.12 no.3
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• pp.337-349
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• 2003

This study was dealt with consumers' attitudes and requests for refunds on the basis of data gathered in 1997 and 2000 and examined factors shaping the differences of the consumers' requesting for refunds and investigated variables influencing the presence or absence of requests for refunds. Research outcomes could be summarized as follows. First there were no differences in consumers' searches for information of refunds, degrees of satisfactions for practices of refunds, knowledges for refunds, consumers' expectation for the permission of refunds between two periods Consumers generally showed more active behaviors for the request for refunds in 2000 than in 1997. In cases of defects, the chance of getting refunds was higher while consumers feel greater needs for refund. Second, consumers perception for the necessity of refund and their expectations for successful outcomes were higher in cases of defects than in the opposite case; consumers were also more active to request for refunds and get more positive responses in the former case. Third, in cases of defects in 1997, as consumers faced the unsatisfactory response for their previous requests for refunds, they did not actively request for refunds. In 2000, requesting for refunds were more active as they were more knowledgeable, actively search for information of refunds before their purchases, and expect more positive outcomes for their requests for refund. On the other hand, in cases of no defects in 1997, consumers showed more active behaviors requesting for refunds as their own professional jobs, owned greater consumer expectation for positive outcomes and showed greater satisfactions for the previous requests of refunds. In the survey of 2000, consumers showed active behaviors requesting for refunds as they were highly educated, gather much information for refund, and showed positive expectations for the possibility of refund.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.504-509
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• 2016

Production processes of double wall bellows can be roughly categorized into two steps. In the first step, inner and outer bellows are made of STS316L in austenite stainless steel due to their excellent formability and corrosion resistance. In the second step, the double wall bellows are manufactured using the welding method with both the inner and outer bellows. The microstructure and defects of each weldment are observed to ensure the reliability of bellows since weldment is a highly vulnerable part, which can crack and fracture when bellows are formed or used. In this study, optimum welding conditions were derived from the analysis of microstructure and inspection of weldment of bellows that were produced using various welding procedure. Moreover, the mechanical properties were evaluated through hardness measurement of substrate, weldment and the heat-affected zone.