• The Journal of the Korea Contents Association
• /
• v.17 no.7
• /
• pp.182-192
• /
• 2017

Recently, there is an increasing interest in analysis of big data that is coming from manufacturing industry. In this paper, we use PCB (Printed Circuit Board) manufacturing data to provide manufacturers with information on areas with high PCB defect rates, and to visualize them to facilitate production and quality control. We use the K-means and DBSCAN clustering algorithms to derive the high fraction of PCB defects, and compare which of the two algorithms provides more accurate results. Finally, we develop a system of MVC structure to visualize the information about bad clusters obtained through clustering, and visualize the defected areas on actual PCB images.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.296-297
• /
• 2015

본 논문에서는 수중함의 전력시스템에 대한 안정성과 신뢰성 분석을 위해 고장나무분석 수행한 결과를 제시한다. 본 논문의 고장나무분석 결과는 추후 수중함 설계 시 현재의 전력 계통 체계에서 전력 생산부와 전력 변환부의 장비 추가와 전력 배전부 구조의 변경가능하게 함으로써 더 우수한 신뢰성과 안정성을 갖는 수중함을 설계 할 수 있는 설계 가이드라인을 제시한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.4
• /
• pp.259-267
• /
• 2022

The existing method of deriving the fail-safe design requirements for the domestic developed rotary-wing aircraft system may miss the factors that cause critical system function failures, when being applied to the latest integrated avionics system. It is because the existing method analyzes the severity effect of the failures caused by a single item. To solve the issue, we present a systematic analysis procedure for deriving fail-safe design requirements of system architecture by utilizing functional hazard assessment and development assurance level analysis of SAE ARP4754A, international standard for complex system development. To demonstrate that our proposed procedure can be a solution for the aforementioned issue, we set up experimental environments that include common factors that can cause critical function failures of a system, and we conducted a cross-validation with the existing method. As a result, we showed that the proposed procedure can identify the potential critical common factors that the existing method have missed, and that the proposed procedure can derive fail-safe design requirements to control the common factors.

• Journal of Korean Society of Steel Construction
• /
• v.24 no.4
• /
• pp.469-478
• /
• 2012

In this study, structural behavior of high tension bolted connections was analyzed in order to investigate effective utilizations. Also, the simplified numerical analysis method showing bolt behavior was proposed using the connector element in the ABAQUS, a nonlinear finite element program and verified by numerical analyses on the basis of the experiment of previous study. In an effort to analyze strength properties of plate girder which high tension bolts are applied to, the effects of each design parameter were compared and analyzed after moment-displacement relations were investigated according to design parameters (upper flange, lower flange, upper and lower flange, web) by action force standards.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.14 no.4
• /
• pp.333-342
• /
• 2009

Three-level Diode Clamped Multilevel Inverter, generally known as Neutral-Point-Clamped (NPC) Inverter, has an inherent problem causing Neutral Point (NP) potential variation. Until now, in many literatures NP potential problem has been investigated and lots of solutions have also been proposed. However, under fault and fault tolerant control, distinctive feature for NP potential variation problem was rarely published from the standpoint of reliability. In this paper, NP potential is analytically investigated both normal and faulty conditions under carrier based PWM. Subsequently, relation between fault detection time and size of capacitor is analyzed. This information is explored by simulation and experiment results, which contribute to enhance the reliability of inverter system.

• Journal of IKEEE
• /
• v.23 no.4
• /
• pp.1218-1223
• /
• 2019

In HVDC systems, the full-bridge submodule increases the number of components compared to the half-bridge submodule, but the failure-rate can be reduced by securing 100 % redundancy. However, full-bridge submodules require more complex control algorithms to ensure the redundancy and to prevent arm-short with sufficient dead-time. To solve this problem, we analyse the failure-rate of the paralleled half-bridge configuration with the same number of components and 100 % redundancy as the full-bridge submodule. The fault tree analysis (FTA) method is applied to the conventional part failure analysis to reflect the operation risk of the submodule, thereby predicting the life-cycle of the submodule more accurately. To verify the validity, the failure-rate results of the proposed FTA based analysis method are compared with the failure rate obtained by the part failure method.

• Journal of Internet Computing and Services
• /
• v.21 no.1
• /
• pp.127-135
• /
• 2020

As the importance of the use and analysis of big data is emerging, there is a growing interest in natural language processing techniques for unstructured data such as news articles and comments. Particularly, as the collection of big data becomes possible, data mining techniques capable of pre-processing and analyzing data are emerging. In this case study with a telecom company, we propose a methodology how to formalize unstructured data using text mining. The domain is determined as equipment failure and the data is about 2.2 million equipment check ledger data. Data on equipment failures by 800,000 per year is accumulated in the equipment check ledger. The equipment check ledger coexist with both formal and unstructured data. Although formal data can be easily used for analysis, unstructured data is difficult to be used immediately for analysis. However, in unstructured data, there is a high possibility that important information. Because it can be contained that is not written in a formal. Therefore, in this study, we study to develop digital transformation method for unstructured data in equipment check ledger.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.3 no.4
• /
• pp.276-281
• /
• 2008

Because the distribution systems experience frequently the fault by several causes, the identification task of fault location plays very important role in the view point of power supply reliability. The distribution systems are designed as radial structure with three-phase and single-phase branch line to supply the electric power to the widely dispersed loads, and it have a several load taps within each line segment. it makes the accurate fault distance determination difficult. Accordingly in this papers, the existing fault point determination methods are surveyed and analyzed, and then a fault distance determination method for distribution feeder is adopted which can be executed effectively in DAS center. Finally, the adopted method is verified using EMTP simulation.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.21 no.5
• /
• pp.515-524
• /
• 2008

The ultimate behavior of high-tension bolted joints with various plate thickness and bolt size is investigated using nonlinear F.E. analysis and experimental study. The relation with sliding load, bolt deformation, and failure modes are presented based on plate thickness and bolt size. Three kinds of the bolt diameter(M20, M22, M24) and five types of the steel plates (l2mm, 16mm, 20mm, 30mm, 40mm) are considered for the ultimate behavior of the bolted joints. The numerical model, constructed by commercial F.E. program, ABAQUS, of ultimate behavior of bolted joints is introduced and verified by experimental results. The force-displacement and force-axial strain relations are measured and compared with the results by 3D finite element analysis.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2011.04a
• /
• pp.3-6
• /
• 2011

IT 기술의 발전에 따른 전력 사용량 증가로 인해서 친환경 재생 에너지에 대한 관심이 집중되고 있는 상황으로 다양한 재생 에너지자원 가운데 풍력에너지 개발이 전 세계적으로 급속히 증가하고 있다. 그러나 풍력발전기를 제어하는 제어기의 소프트웨어·하드웨어적인 문제로 인해 불규칙한 에너지 생산과 유지보수를 위한 비용이 증가함에 따라 최근에는 풍력제어기의 고장분석 및 고장 감내 제어에 대한 연구가 활발히 진행되고 있는 상황이다. 본 논문에서는 이와 같은 풍력발전기가 지속적으로 일정한 에너지 생산과 유지보수 절감이 가능하도록 하기 위해 풍력제어시스템 차원에서의 고장에 대해서 감내 가능한 고가용성의 미들웨어에 대한 구조를 제안한다. 풍력제어시스템의 고 가용성 미들웨어는 가상 운영체제를 기반으로 이중화 구조를 가지고 있으며, 주 운영체제에서 소프트웨어적인 고장이 발생 시 다음 우선순위의 가상 운영체제에서 지속적인 서비스를 제공할 수 있도록 각각의 가상 운영체제 환경을 관리한다.