• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3852-3859
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• 2021

This paper presents experimental and numerical analysis results regarding the effects of an incomplete penetration defect on the fatigue lives of socket welded pipes. For the experiment, four-point bending fatigue tests with various defect geometries (defect depth and circumferential length) were performed, and test results are presented in terms of stress-life data. The results showed that for circumferentially short defects, the fatigue life tends to increase with increasing crack depth, but for longer defects, the trend becomes the opposite. Finite element analysis showed that for short defects, the maximum principal stress decreases with increases in crack depth. For a longer defect, the opposite trend was found. Furthermore, the maximum principal stress tends to increase with an increase in defect length regardless of the defect depth.

• International Journal of Internet, Broadcasting and Communication
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• 제14권3호
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• pp.149-154
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• 2022

In recent years, the application of deep learning method to computer vision has shown to achieve great performances. Thus, many research projects have also applied deep learning technology to railroad defect detection. In this paper, we have reviewed the researches that applied computer vision based deep learning method to railroad defect detection and inspection, and have discussed the current trend and the direction of those researches. Many research projects were targeted to operate automatically without visual inspection of human and to work in real-time. Therefore, methods to speed up the computation were also investigated. The reduction of the number of learning parameters was considered important to improve computation efficiency. In addition to computation speed issue, the problem of annotation was also discussed in some research projects. To alleviate the problem of time consuming annotation, some kinds of automatic segmentation of the railroad defect or self-supervised methods have been suggested.

• 한국산학기술학회논문지
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• 제16권1호
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• pp.691-696
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• 2015

소프트웨어 결함에 대한 관심이 높아지고 있다. 기업은 소프트웨어를 개발하는 조직, 고객대응 조직, 품질관리 조직 등 다양한 방법과 채널을 이용하여 개선을 위한 노력을 하고 있다. 이렇게 수집된 결함 데이터 들을 그 조건과 용도에 맞게 분석하여 소프트웨어 결함을 최소화하고 나아가 제품품질 향상에 기여할 수 있다. 본 연구에서 기업용 소프트웨어의 결함 추이를 테스트 성숙도 모델을 기반으로 분석하여 결함 예방 프로세스를 수립하고 프로젝트에 적용하여 106개의 결함이 16개로 감소하였다. 본 연구는 소프트웨어 품질활동 중 기본이 되는 기존결함에 관심을 가짐으로서 최소한의 자원을 활용하여 소프트웨어 제품 품질을 개선할 수 있는 방안을 제시하는데 의의를 가진다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.155-156
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• 2018

Apartment houses are now a popular form of general housing, and the construction techniques and materials quality used to construct apartments are also continuously evolving as if they were representative. However, issues concerning flaws are constantly being reported in the press. This study attempts to analyze the trend of conflicts related to defects and to analyze the types of defects received in the apartment building, to suggest the development of the integrated defect management system, and to develop the construction based on the development of the system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권7호
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• pp.1817-1839
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• 2024

To solve the problem of insufficient recognition of key nodes in the existing software defect detection process, this paper proposes a key node recognition algorithm based on node expansion degree and improved K-shell position, shortened as SDD_KNR. Firstly, the calculation formula of node expansion degree is designed to improve the degree that can measure the local defect propagation capability of nodes in the software network. Secondly, the concept of improved K-shell position of node is proposed to obtain the improved K-shell position of each node. Finally, the measurement of node defect propagation capability is defined, and the key node recognition algorithm is designed to identify the key function nodes with large defect impact range in the process of software defect detection. Using real software systems such as Nano, Cflow and Tar to design three sets of experiments. The corresponding directed weighted software function invoke networks are built to simulate intentional attack and defect source infection. The proposed SDD_KNR algorithm is compared with the BC algorithm, K-shell algorithm, KNMWSG algorithm and NMNC algorithm. The changing trend of network efficiency and the strength of node propagation force are analyzed to verify the effectiveness of the proposed SDD_KNR algorithm.

• Smart Structures and Systems
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• 제32권4호
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• pp.253-266
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• 2023

The time-reversal method is employed to improve the ability of pipeline defect detection, and a new approach of identifying the pipeline defect depth is proposed in this research. When the L(0,2) mode ultrasonic guided wave excited through a lead zirconate titinate (PZT) transduce array propagates along the pipeline with a defect, it will interact with the defect and be partially converted to flexural F(n, m) modes and longitudinal L(0,1) mode. Using a receiving PZT array attached axisymmetrically around the pipeline, the L(0,2) reflection signal as well as the mode conversion signals at the defect are obtained. An appropriate rectangle window is used to intercept the L(0,2) reflection signal and the mode conversion signals from the obtained direct detection signals. The intercepted signals are time reversed and re-excited in the pipeline again, result in the guided wave energy focusing on the pipeline defect, the L(0,2) reflection and the L(0,1) mode conversion signals being enhanced to a higher level, especially for the small defect in the early crack stage. Besides the L(0,2) reflection signal, the L(0,1) mode conversion signal also contains useful pipeline defect information. It is possible to identify the pipeline defect depth by monitoring the variation trend of L(0,2) and L(0,1) reflection coefficients. The finite element method (FEM) simulation and experiment results are given in the paper, the enhancement of pipeline defect reflection signals by time-reversal method is obvious, and the way to identify pipeline defect depth is demonstrated to be effective.

• 정보처리학회논문지A
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• 제17A권2호
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• pp.81-92
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• 2010

진동 정보를 통해 기계 설비의 상태나 고장 유무를 판단하는 연구들이 다수 진행 중에 있는데, 대부분의 연구에서는 설비에 대한 진동을 모니터링하거나 고장 유무를 판별하여 사용자에게 알리는 수준이다. 본 논문에서는 진동에 의한 고장 진단과 판별을 보다 정교하게 수행하는 선박 엔진의 고장 감지 기법과 시스템을 제안하였다. 일차적으로 이중적 진동 정보 판별 기법을 적용하여 진동 정보를 확인한 다음에 고장 유무를 검사한다. 만일 고장이 발생한 경우에는 진동 정보의 오류 부분만을 이용하여 고장 진동 파형에 대한 오차 범위를 기준으로 어떤 유형의 고장인지를 판별할 수 있는 기법을 적용하였다. 또한 선박의 진동 경향 분석과 엔진 안전 보존을 목적으로 진동 정보를 데이터베이스에 저장하고 추적할 수 있도록 시스템을 구현하였다. 제안 시스템을 선박 엔진의 고장 판별 유무와 고장 진동 파형 감별 인자에 대해 실험을 수행한 결과 고장 유무 판별은 약 100% 정확성을 가졌고 고장 진동 파형의 유형 인식에서는 약 96% 정확성을 가졌다.

• 한국건설관리학회논문집
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• 제23권5호
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• pp.23-33
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• 2022

공동주택의 하자소송 금액에서 가장 많은 비율을 차지하고 있는 균열하자는 하자판정 기준이 명확하지 않아 판결에 따라 하자에 관한 판단이 엇갈리고 있다. 균열하자 판결금액 대부분을 차지하는 층간균열은 균열의 폭이나 상태와 관계없이 모두 하자로 판정되는 추세이며, 보수공법 또한 대부분 일률적으로 정해지고 있다. 이는 균열하자 판정의 기준이 되는 국토교통부의 하자판정기준과 법원에서 기준을 삼는 건설감정실무의 기준이 일치하는 않는 문제에서 출발한다. 법령의 개정과 법원감정실무지침서의 개정 등을 통해 모든 이해관계자가 적용할 수 있는 하자판정 기준의 수립이 필요하다. 또한, 층간균열 보수공법 기준은 층간균열의 폭과 상태에 따라 공법을 적용할 필요성이 있다. 균열에 대한 하자판정과 보수공법적용을 합리화한다면 소송에만 의존하는 현재의 하자분쟁 추세를 바꿀 수 있는 계기가 될 수 있을 것이다.

• 한국소음진동공학회논문집
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• 제16권4호
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• pp.366-371
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• 2006

As functional requirements of automatic office machines like printers, Automatic Tellex Machines(ATMs), copying machines are on a trend for the higher speed and precision, extensive technical advances are being developed and implemented in the industry. Media transport system is a device to convey a sheet of paper in ATMs and printers. The stability of media transport system is a matter of concern as their operating throughput rapidly increases. And defects of belts or rollers in a transport system directly affect the level of stability of the system. Therefore an automatic diagnostic system for predicting various defects is necessary for the stable operation of the media transport system. A simulation based on multi-body dynamics has been done for a feasibility study of a system design for the defect anticipation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.564-568
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• 2005

As functional requirements of automatic office machines like printers, ATMs, copying machines are on a trend for the higher speed and precision, extensive technical advances are being developed and implemented in the industry. Media transport system is a device to convey a sheet of paper in ATMs and printers. The stability of media transport system is a matter of concern as their operating throughput rapidly increases. And defects of belts or rollers in a transport system directly affect the level of stability of the system. Therefore an automatic diagnostic system for predicting various defects is necessary for the stable operation of the media transport system. A simulation based on multi-body dynamics has been done for a feasibility study of a system design for the defect anticipation.