• 대한안전경영과학회지
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• 제19권1호
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• pp.15-25
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• 2017

The findings were summarized as follows. The safety check by manufacturer showed that 6 of 13 companies are over the average occurrence of defects. It was expected that there would be a difference between manufacturing technology capability and production system of each manufacturer. Consequently, manufacturers should institutionally improve and strengthen certification items for the upward standardization of safety certification before factory. Second, the safety check by year showed that the results of this study accord with those of previous studies on defect time. Consequently, manufacturers should classify the 3-year-old equipment for vehicle-mounted MEWP into a special check subject to do a nondestructive test according to proven results, and also reflect the test in a safety test system to do regular preventive activities of equipment defects. Third, the safety check by part showed that the boom and outrigger parts of vehicle-mounted MEWP have the most defects. Stress concentration resulted in defects as the boom part was most frequently operated in the structural parts for a real work. To prevent this, it is suitable to improve the hardness of boom materials. The outrigger part needs improvement in safety devices with materials. As an outrigger supports the overturning moment of equipment, it is most affected by its load based on the operating radius, resulting in fatigue crack.

• 반도체디스플레이기술학회지
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• 제19권4호
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• pp.59-64
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• 2020

In this paper, we found the solution using data based machine learning regression method to check the pore shape, to solve the problem of the experiment quantity occurring when producing scaffold with the 3d printer. Through experiments, we learned secured each print condition and pore shape. We have produced the scaffold from scaffold pore shape defect prediction model using multiple linear regression method. We predicted scaffold pore shapes of unsecured print condition using the manufactured scaffold pore shape defect prediction model. We randomly selected 20 print conditions from various predicted print conditions. We print scaffold five times under same print condition. We measured the pore shape of scaffold. We compared printed average pore shape with predicted pore shape. We have confirmed the prediction model precision is 99 %.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.546-550
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• 2008

교육시설물 공사에는 중견 건설업체들의 참여가 주를 이루고 있다. 이는 전문 인력 부족, 시공경험부족과 노하우 부족 등의 문제점을 가지고 있어 체계적인 품질관리를 하지 못하고 있다. 건축공사에서 발생하는 하자사례 중 많은 부분이 누수에 의한 것이며, 누수방지는 설계, 시공, 그리고 유지보수에 있어 세심한 관리가 요구되고 있다. 따라서 본 연구에서는 교육시설물의 누수 사례를 살펴보고 교육시설물의 공법별, 공간별, 부위별, 단계별(설계, 시공, 관리) 계획 시 고려 해야하는 요인의 분류체계를 구축하여 누수방지 Check List를 작성하도록 한다.

• 융합보안논문지
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• 제20권2호
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• pp.145-153
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• 2020

2018년부터 시행된 항공안전정책기본계획은 무결점 항공안전관리체계 구축과 미래 항공안전 인프라 구축을 목표로 4차 산업혁명 기술을 적용한 항공안전관리 기술 개발을 포함하고 있다. 인공지능과 빅데이터를 활용한 항공기 고장관리, 가상/증강현실 기술을 활용한 비행훈련체계 등 다양한 항공안전관리 체계를 구축하고자 한다. 현재 공군에서도 스마트한 공군력 건설이라는 목표 아래 신기술을 활용한 비행안전관리 체계 사업을 추진 중이다. 본 연구에서는 비행 전에 항공기의 최종 안전성을 점검하는 항공기 상태 점검체계를 4차 산업혁명기술을 적용하여 설계하고자 한다. 공군에서는 항공기 상태 점검으로 기골 결함 점검과 비행 전 항공기 종합점검을 실시한다. 본 연구에서는 최소한 점검 오류를 줄일 수 있는 무결점 점검을 위해서 인공지능, 사물인터넷, 빅데이터, 그리고 드론을 활용한 기골 결함 점검체계와 비행 전 항공기 상태 점검체계 설계를 제안한다.

• 한국정밀공학회지
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• 제29권6호
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• pp.613-620
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• 2012

Rails are subjected to damage from rolling contact fatigue, which leads to defects such as cracks. Rolling contact fatigue damages on the surface of rail such as head check, squats are one of growing problems. Another form of rail surface damage, known as "Ballast imprint" has become apparent. This form of damage is associated with ballast particles becoming trapped between the wheel and the surface of rail. These defects are still one of the key reasons for rail maintenance and replacement. In this study, we have investigated whether the ballast imprint is an initiator of head check type cracks and effect of defect size using Finite element analysis. The FE analysis were used to investigate stresses and strains in subsurface of defects according to variation of defect size. Based on loading cycles obtained from FE analysis, fatigue analysis for each point was carried out.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.364-367
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• 2007

In nano-imprint lithography (NIL) process, which has shown to be a good method to fabricate polymeric patterns, several kinds of pattern defects due to thermal effects during polymer flow and mold release operation have been reported. A typical defect in NIL process with high aspect ratio and low resist thickness pattern is a resist fracture during the mold release operation. It seems due to interfacial adhesion between polymer and mold. However, in the present investigation, FEM simulation of NIL molding process was carried out to predict the defects of the polymer pattern and to optimize the process by FEA. The embossing operation in NIL process was investigated in detail by FEM. From the analytical results, it was found that the lateral flow of polymer resin and the applied pressure in the embossing operation induce the weld line and the drastic lateral strain at the edge of pattern. It was also shown that the low polymer-thickness result in the delamination of polymer from the substrate. It seems that the above phenomena cause the defects of the final polymer pattern. To reduce the defect, it is important to check the initial resin thickness.

• 품질경영학회지
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• 제50권3호
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• pp.533-543
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• 2022

Purpose: The purpose of this study is to identify and resolve the causes of defects in the unmanned aerial vehicle launch system(propulsion wire fracture, rear rail deformation) and to prevent recurrence. Methods: The causes of the two defects were derived through fault tree analysis for each of the two defects and fault reproduction tests. In the case of propulsion wire, the installation of a high speed camera to check the behavior of wire was the driving force behind the defect resolution. Results: The results of this study are as follows; It was determined that the thickness of the washer was less than the maximum tolerance of the pulley was the cause of the propulsion wire fracture defect. Failure to comply with the launch procedure and insufficient safety margin were judged as the cause of the rear rail deformation defect. Accordingly, the configuration was changed to remove each defect. Conclusion: The case of this study was conducted to eliminate defects in the launch system for UAV. The causes of defects were estimated through fault tree analysis. After the configuration change, Structural analysis and launch tests were performed to demonstrate the safety and effectiveness of the modified configuration. As a result, the effect of the modified configuration was verified.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제11권6호
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• pp.229-236
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• 2022

사물인터넷을 기반으로 실시간으로 소화기 주변의 상태와 화재 발생 여부, 소화기의 상태를 확인할 수 있는 웹 시스템과 화재 알림을 받을 수 있는 애플리케이션을 구현한다. 해당 시스템의 목표를 명확하게 정하고 구조를 상세히 정의함으로써 개발 도중 일어나는 오류를 최소화한다. 또한, 스마트소화기에 대한 요구분석과 설계, 구현 단계에서 제품 결함을 찾아내고 그 원인을 분석하여 결함을 줄이는 방법을 제안한다. 제안하는 연구를 통해 IoT 기반의 스마트 소화기에 대해 결함관리 신뢰성을 확보할 수 있다.

• 전기전자학회논문지
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• 제25권4호
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• pp.689-696
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• 2021

본 논문에서는 고장예측진단 및 건전성 관리 기법(Prognostics and Health Management, PHM)을 적용하기 위해 해당 시스템 혹은 회로 내부에서 결함특성을 감지하고 예측할 수 있는 회로 구조를 제안하였다. 기존 연구에서 회로 결함의 진행에 따라, S-parameter 크기 최소값의 주파수가 변화하는 것을 확인하였다. 이러한 특성을 기존에는 네트워크 분석기(Network Analyzer)를 활용하여 측정하였으나, 본 연구에서는 같은 결함검출기법을 활용하더라도 큰 계측장비 없이 결함의 진행상황 및 잔여 수명, 결함발생 여부를 확인할 수 있는 소형화된 회로를 설계하였다. 본 연구에서는 S-parameter의 변화를 야기하는 임피던스의 변화를 감지할 수 있도록 회로를 설계하였으며, Bond-wire의 온도반복에 따른 S-parameter 변화 측정결과를 제안하는 회로에 적용하였다. 이를 통해 해당 회로가 Bond-wire의 결함을 감지할 수 있다는 것을 성공적으로 검증하였다.

• Journal of Periodontal and Implant Science
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• 제37권2호
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• pp.181-192
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• 2007

Periodontal surgery as part of the treatment of periodontal disease is mainly performed 1) to gain access to diseased areas for adequate cleaning; 2) to achieve pocket reduction or elimination; and 3) to restore the periodontal tissues lost through the disease; i.e., a new attachment formation of periodontal regeneration. To accomplish the latter, often referred to as the ultimate goal of periodontal therapy, a number of surgical procedures have been advocated throughout the years. Clinical studies have demonstrated that considerable gain of clinical attachment and bone can be achieved following guided tissue regeneration (GTR) therapy of intrabony defects. The aim of this study was to analyse the radiographic bone changes 2-year after GTR using a bone graft material and nonresorbable membrane. Patients attending the department of periodontics of Kyungpook National University Hospital were studied. Patients had clinical and radiographic evidence of intrabony defect(s), 33 sites of 30 patients aged 32 to 56 (mean age 45.6) were treated by GTR with a bone graft material and nonresorbable membrane. Baseline and 2-year follow-up radiographs were collected and evaluated for this study. Radiographic assessment includes a bone fill, bone crest change, defect resolution, and % of defect resolution. Pre- and post-treatment differences between variables (maxilla and mandible, defect depth, defect angle, bone graft materials) using the paired t-test were examined. We observed $2.86{\pm}1,87mm$ of bone fill, $065{\pm}0.79mm$ of crestal resorption, $3.49{\pm}2.11mm$ of defect resolution, and $44.42{\pm}19.51%$ of percentage of defect resolution. Mandible, deeper initial defect depth, narrower initial defect angle showed greater bone fill, defect resolution, and % of defect resolution. But no difference was observed between xenograft and allograft. Outcome of GTR as a therapy of intrabony defect was better than other therapy, but herein, good oral hygiene maintenance as a anti-infective treatment and periodic recall check of patients are essential.