• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.4
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• pp.591-597
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• 2022

Recently, many studies have been done on the data augmentation technique as a way to efficiently build datasets. Among them, a representative data augmentation technique is a method of utilizing Generative Adversarial Network (GAN), which generates data similar to real data by competitively learning generators and discriminators. However, when learning GAN, there are cases where a broken pixel image occurs among similar data generated according to the environment and progress, which cannot be used as a dataset and causes an increase in learning time. In this paper, an algorithm was developed to select these damaged images by analyzing the histogram of image data generated during the GAN learning process, and as a result of comparing them with the images generated in the existing GAN, the ratio of the damaged images was reduced by 33.3 times(3,330%).

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.218-227
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• 2006

• Fire Science and Engineering
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• v.29 no.6
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• pp.40-44
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• 2015

National and international standards for curtain wall glass are focused on wind pressure and insulation performance, but disasters such as fires and earthquakes are not considered. Failure of curtain wall glass during a fire in a skyscraper increases the loss of lives and property due to the spread of fire. Therefore, the fire resistance of curtain wall glass should be investigated, and technology to prevent glass failure should be developed to prevent fire damage due to spreading fire. It is important to predict the starting point of cracks and the cause of glass failure to prevent it effectively using the limited water in a skyscraper. In this study, double glazed glass was exposed to a radiator in an experiment performed to analyze the thermal characteristics. The results show that glass that was not directly exposed to high temperature and pressure was broken. To identify this failure case, numerical analysis was performed. Three glass specimens were installed in an ISO 9705 room and exposed to radiation using a radiator, and a thermocouple was used to measure the temperature on the surface of the glass. Widely used double glazed glass was analyzed for weakness to fire.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.175-185
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• 2017

As the gas is manufactured, handled and used more often due to the continuous increase of gas, the related facility gets expanded and more complex causing small and big accident which causes economic loss including damage for humans and materials. The gas pipeline, the most common gas facility, has the biggest risk of accidents. Especially in the urban area and densely populated areas, the accident due to the high pressure pipeline may cause even more serious damages. To prevent the accident caused by the buried pipeline, it is required for the relevant authorities to evaluate the damage and risk of the whole pipeline system effectively. A risk is usually defined as a possibility or probability of an undesired event happening, and there is always a risk even when the probability of failure is set low once the pipeline is installed or under operation. It is reported that the accident caused by the failure of the pipeline rarely happens, however, it is important to minimize the rate of accidents by analyzing the reason of failure as it could cause a huge damage of humans and property. Therefore, the paper rated the risk of pipelines with quantitative numbers using the qualitative risk analysis method of the Scoring Model. It is assumed that the result could be effectively used for practical maintenance and management of pipelines securing the safety of the pipes.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.120-120
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• 2018

반도체 소자나 디스플레이 패널 제조 공정에 가장 많이 사용되는 진공 펌프인 터보 분자 펌프는 오일을 사용하지 않고, 설치 방향이 자유로우며 넓은 작동 압력 영역을 가지고 있어서 고가임에도 불구하고 점점 더 사용 영역을 넓혀 가고 있다. 상하의 두 곳에 회전축을 지지하는 베어링이 필요한데, 기계식 금속 베어링을 채용하는 경우에는 반드시 윤활유를 공급해 주어야 하고, 고온, 부식성 또는 산화성 가스의 배기 시에는 퍼지 가스로 비활성인 질소나 알곤등을 이용하여 보호를 해주어야 한다. 반면, 자기 베어링을 채택한 모델은 윤활의 걱정에서 자유로울 수 있기 때문에 채용이 늘어나고 있다. 동일극의 반발력이나 반대극의 인상력을 이용한 구조를 갖게 되는데 갑작스러운 입구 쪽 압력의 증가 시에는 자석 끼리 부딪치는 일이 발생하고 이로 인해서 로터 모듈 전체에 큰 손상을 갖게 되므로 한 곳 정도에 비상용 터치 다운 베어링을 기계식으로 윤활제 없이 설치하기도 한다. 기본적으로 자기 베어링 방식은 로터 모듈의 부상과 제어를 위해서 3축 또는 5축 제어를 하게 되는데 여기에는 전자석의 전류를 미세하게 조정하여 피드백 하는 시스템을 활용하기 때문에 외부에서의 자기장이 일정값 이상 침투하게 되면 제어 회로의 기능에 문제를 일으키게 된다. 또한 축 방향에 수직인 자기장의 강도가 높아지면 고속으로 회전하는 금속 블레이드가 자속을 자르게 되므로 표면에 와전류가 발생하여 문제가 된다. 터보 분자 펌프는 회전자와 고정자 간격이 1 mm 이내로 작아서 약간의 진동이라도 발생하면 회전자와 고정자 간에 충돌이 일어나고 이는 곧 파손으로 이어진다. 그림 1에는 파손 원인 분석을 위한 회전자 모듈의 수치 해석용 모델의 일부를 나타내었고, 그림 2에는 실제로 외부 자기장에 의한 파손이 발생한 사례의 자기 베어링 모듈의 사진을 나타내었다. 본 발표에서는 외부 자기장의 형태에 따라 제어 자기장에 미치는 영향을 CFD-ACE+(ESI corp)를 활용하여 해석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.487.2-487.2
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• 2014

일반적으로 PV모듈은 태양전지의 내구성을 보완하기 위해 유리, EVA, Back-sheet, Frame등을 사용하여 보호하게 된다. 이렇게 하나의 PV모듈로 만들어져 약 20년간 옥외에 노출 되면서 다양한 하중에 노출된다. PV모듈의 변형이 발생하면서 PV모듈 내부에 위치하는 태양전지도 다양한 원인에 의해 외부에서 힘을 받음으로써 변형이 일어나고 심지어 태양전지의 파손이 발생 되는 경우도 있다. 따라서 PV모듈 내에 존재하는 태양전지가 외부하중에 의한 내구성을 확보하기 위해서는 유리, EVA, Frame과 같은 PV모듈 구성소재가 하중에 대한 변형량을 분석함으로써 태양전지 파손을 방지할 수 있는 구조 및 재료 연구에 활용 될 수 있을 것으로 판단된다. 이를 분석하기 위해 강화유리를 중심으로 EVA, 태양전지, Back-sheet의 적층화 과정에서 외부하중에 대한 변형량 비교와 강화유리, EVA 두께 변화에 따른 변형량, 라미네이션(Lamination)된 모듈과 프레임 사이의 접착력이 변형량에 어떤 영향을 미치는 확인하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.959-965
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• 2017

In recent years, major airplane manufacturers have been using the laminate failure theory to estimate the strain of composite structures for airplanes. The laminate failure theory uses the failure strain of the laminate to analyze composite structures. This paper describes a procedure for the experimental assessment of laminate tensile failure characteristics. Regression analysis was used as the experimental assessment method. The regression analysis was performed with the response variable being the laminate failure strain and with the regressor variables being two-ply orientation ($0^{\circ}$ and ${\pm}45^{\circ}$) variables. The composite material in this study is a carbon/epoxy unidirectional (UD) tape that was cured as a pre-preg at $177^{\circ}C(350^{\circ}F)$. A total of 149 tension tests were conducted on specimens from 14 distinct laminates that were laid up at standard angle layers ($0^{\circ}$, $45^{\circ}$, $-45^{\circ}$, and $90^{\circ}$). The ASTM-D-3039 standard was used as the test method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.7
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• pp.549-555
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• 2021

Open hole strength of composite laminates is often used as the design allowable strength for designing composite aircraft structures, particularly those structures subjected to impact loading. Generally, the degradation of strength due to a barely visible impact damage (BVID) is assumed as the strength of 6.0 mm hole diameter in 24.0 mm width specimen. In this study, the residual strength static tests of composite laminates containing circular holes have been performed to investigate the effects of fiber orientation structure on open hole strength. The point stress criterion using a characteristic length is used to predict the open hole strength. The finite element analysis has been used to validate the analytical method. From the test results, it is shown that the characteristic length is related to the percentage of 0°, ±45° and 90° plies of the laminate. And regression analysis has performed to determine the characteristic length and strength of no hole specimens on the arbitrary layup pattern.

• Journal of the Korean Institute of Gas
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• v.22 no.3
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• pp.53-64
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• 2018

Natural gas is an explosive fluid and can cause severe human/material damage when buried high-pressure pipeline is failure, and there have been reported cases of considerable human life damage to actual buried pipeline failure. In domestic cases, the length and duration of pipeline operating are short due to rapid growth. Therefore, it is a fact that the establishment of effective accident data is insufficient for the cause of the accident. In order to systematically construct an accident database, the operation history of natural gas pipeline is longer than domestic, and the cause and frequency analysis of recent natural gas pipeline related accidents occurred in overseas major countries with a long pipeline network was conducted. Then, after grasping the trend of occurrence frequency by incident cause, we tried to establish the foundation for securing the stability of the domestic high-pressure gas transport pipeline network.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.211-216
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• 1995

1994년 11월에 나타난 고리 1호기 증기발생기의 전열관 누설에 대한 원인을 조사하기 위하여 인출 전열관의 파손 분석과 슬러지 분석 및 pH 분석 등을 수행하였다. 손상원인은 국부적인 염기도 상승과 부식전위 상승에 따른 2차측 응력부식균열(ODSCC)로 밝혀졌다. 전열관 표면과 접한 관판 상부의 퇴적슬러지 끝단에 형성된 틈새에서 나타나는 비등현상으로 $Na^{+}$ 등의 양이온이 농축하게 되며, Cl$^{-}$ 등의 음이온 증발로 인하여 국부적으로 염기도의 상승현상이 야기되었다. 또한 재 가동시 전열관 표면에 침착된 잔류 구리와 용존산소의 결합으로 부식전위가 상승되었다. 이와 같은 ODSCC 발생환경은 1990년이래 지속적으로 형성된 것으로 판단된다.