• 전기학회논문지
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• 제59권10호
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• pp.1869-1873
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• 2010

For reliable operation of oil-filled electrical equipment, monitoring and maintenance of insulating oil is essential. Dissolved gas analysis(DGA) is widely used for monitoring faults in high voltage electrical equipment in service. Therefore, oil analysis should be monitored regularly during its service life. KEPCO has investigated thousands of dissolved gas analysis data since 1985, and conducted studies on the relationship of gas in oil analysis and internal inspection results of transformer. As the results, KEPCO revised criteria for transformer diagnosis and has applied it since 2008. Almost of 100 cases of internal inspection results since 2001 have been investigated. This paper presents the correlation of the fault-identifying gases with faults found in actual transformers and how should we approach to internal inspection of transformer by dissolved gas analysis.

• 한국공작기계학회논문집
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• 제17권3호
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• pp.71-77
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• 2008

This paper presents a stereo vision based autonomous inspection system for welding quality control of a RV(Recreational Vehicle) sinking seat. The three dimensional geometry of the welding bead, which is the welding quality criteria, is measured by using the captured stereo images with a median filter applied on it. The image processing software for the system was developed using the NI LabVTEW software with NI vision system. In the manufacturing process of a RV sinking seat, the developed system can be used for overcoming the precision error that arises from a visible inspection by an operator. The welding quality inspection system for RV sinking seat was verified using experimentation.

• 한국구조물진단유지관리공학회 논문집
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• 제24권6호
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• pp.197-205
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• 2020

주택법(2014년)에 근거하여 철근콘크리트 공동주택의 리모델링 시 수직 및 세대수 증축이 가능하게 되었다. 수직증축 리모델링 가능 여부는 안전진단 기준 및 매뉴얼을 바탕으로 기울기 및 침하, 내하력, 내구성 평가 부문에 대한 평가를 통하여 판정하도록 되어 있다. 그러나 증축형 리모델링 기준 및 매뉴얼 제정 당시, 국내에서는 수직증축 리모델링 안전진단 사례가 전무하여 평가기준 등에 대한 공학적 근거 제시에 한계가 있었으며, 특히 내구성 평가 기준에 대한 합리화 및 관련 기준과의 부합을 위한 개선이 필요한 것으로 생각된다. 따라서 본 연구에서는 국내외 내구성 관련 기준을 근거로 콘크리트 탄산화, 염분함유량, 균열, 철근부식, 표면노후도의 허용치와 평가기준에 대한 검토·분석을 통하여 수직증축형 리모델링 안전진단 내구성 평가방법의 합리화 방안을 제시하였다.

• 한국도로학회논문집
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• 제18권6호
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• pp.115-122
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• 2016

OBJECTIVES : This study develops an evaluation method, which is useful to inspect pavement condition of specific boroughs. This is because pavement condition is broadly divided into five grades via visual inspection, which does not consider the types of deteriorations, and is decided by an investigator having a subjective viewpoint. This visual inspection method is not a satisfactory method for accurate maintenance when various deteriorations occur. METHODS : The performance model considers several factors such as crack, rutting, and IRI. This method is also modified from borough SPI based on SPI (Seoul Pavement Index). Considering limited budget of borough, PI (prediction index) is suggested, which is related to the grade of pavement condition evaluation and type of materials. Practical correlation review is also conducted with statistical verification by using the Monte Carlo simulation. RESULTS : The results of the study show that modified criteria are reasonable. First, the comparison between the visual inspection result and the SPI result indicates that the R-square value is sufficiently high. Second, through the common section, each evaluation method could be compared, and the result shows considerable similarity, which increases when the range is modified. Finally, PI for predicting remaining life and the random number SPI have common parts, which means that each indicator would be adequate to be used as an evaluation method. CONCLUSIONS : Comparison and analysis results show that the developed evaluation method is reasonable for specific boroughs where financial support is inadequate for the evaluation process by using the newer equipment. Moreover, for more accurate evaluation method, previous visual inspection data should be utilized, and the database of inspection equipment have to be collected.

• Communications for Statistical Applications and Methods
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• 제17권5호
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• pp.745-753
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• 2010

감사원은 각종 감사에서 증거자료로 공공부문의 정보시스템 데이터를 많이 활용하고는 있으나 데이터 자체의 신뢰성을 제대로 점검하지 못하고 있는 실정이다. 따라서 본 연구에서는 해외 선진 감사원의 감사사례를 분석하여 우리나라 공공부문의 데이터 신뢰성을 체계적으로 점검하는 기법을 개발하였다. 그리고 적용사례로 한국장애인고용공단에서 관리하고 있는 장애인고용부담금 데이터를 분석하여 점검기법의 적용가능성을 검증하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1624-1630
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• 2011

Currently the train operating environment to affect track irregularity is changed rapidly such as speed-up, linear improvement and rolling stack upgrade. The recent track maintenance criteria of track irregularity was quoted from past Japan's, and the needs of revision of criteria are increased because of the rapid change in train operating environment. In case of enhance the track irregularity criteria, it secure driving safety and riding comfort but maintenance cost are increase. And also decrease ballast durability by frequent corrective work. In case of mitigate the criteria, it decrease driving safety and riding comfort, but save the maintenance cost. The study for enacting rational criteria did not carry out so far. In this study, survey the domestic and international track irregularity and case study for track irregularity inspection results and maintenance history for guideline of enacting irregularity criteria study.

• 산업경영시스템학회지
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• 제21권47호
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• pp.101-112
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• 1998

Recently, researchers show growing interest on product quality characteristic dependence and designing acceptance sampling plans under the quality dependence. This research intends to resolve a few theoretical and practical questions for better application of acceptance sampling when the quality characteristic of product items exhibits a statistical dependence and samples are inspected according to the production order. In this research, a mathematical programming model is developed for the economic modeling of sampling plans based on two evaluation criteria : the average outgoing quality(AOQ) and the average total inspection cost. An efficient solution procedure is then proposed using the functional structure of the two evaluation criteria and the procedure is numerically illustrated.

• 반도체디스플레이기술학회지
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• 제3권4호
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• pp.51-55
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• 2004

In the design stage of high precision manufacturing/inspection FAB facilities, it is necessary to investigate the allowable vibration limits of high precision equipments and to study structural dynamic characteristics of C/R and Sub-structure in order to provide structural vibration criteria to satisfy these allowable limits. The goal of this study is to investigate the dynamic characteristics of PC-Type mock-up structures designed for next generation TFT-LCD FAB through experiments and analysis procedures. Therefore, in order to provide a proper dynamic structural design for high precision manufacturing/inspection work process, these allowable limits must be satisfied.

• Corrosion Science and Technology
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• 제11권5호
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• pp.179-183
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• 2012

As one of promising solutions to overcome high oil price and energy crisis, the construction market of high value-added LNG plants is spotlighted world widely. The purpose of this study is to introduce LNG-RBI system to develop risk assessment technology with RAM(Reliability, Availability, Maintainability) modules against overseas monopolization. After analyzing relevant specific features and their technical levels, risk assessment program, non-destructive reliability evaluation strategy and safety criteria unification class are derived as core technologies. These IT-based convergence technologies can be used for enhancement of LNG plant efficiency, in which the modular parts are related to a system with artificial optimized algorithms as well as diverse databases of facility inspection and diagnosis fields.

• Journal of Welding and Joining
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• 제19권1호
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• pp.40-48
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• 2001

An ultrasonic test method, as a nondestructive test is applied to ensure the clad interface quality assessment. According to the reference codes and standards, not only korea Industrial Standard(KS) but also American Society for Testing and Materials (ASTM) Standard, ultrasonic examination procedures use the pulse-echo, A-scan, back reflection signal drop method and/or side drilled reference hole used to establish the acceptance criteria of clad material test. But the variety of bonding materials and sizes makes it difficult to produce the reference blocks, or thus the criteria. In order to overcome these practical difficulties, new ultrasonic testing criterion is suggested. In this new method, the theoretical interface reflection signal amplitude level is calculated and suggested as an acceptance criteria with the back reflection signal set to 100% FSH(Full Screen Height) which is based on acoustic impedance mismatch at the clad interface for the explosive clad ultrasonic inspection. Applicability of suggested criterion, for the explosive clad Fe-Naval Brass with different bonding quality is confirmed to the pre-existed KS and ASTM specifications and verified by using SEM (Seanning Electron Microscope) micrograph. The results obtained by the suggested method is more conservative than the results according to the KS B 0234 and ASTM A 578 specifications The suggested method could be applicable to any other combination of explosive clad ultrasonic inspection.