• Transactions of Materials Processing
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• v.14 no.6 s.78
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• pp.541-546
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• 2005

Apparent mechanical properties in structural components can be different from the initially designed values due to the formation of the residual stress in metal forming and welding. Therefore, the evaluation of residual stress has great importance in the reliability diagnosis of structural components. A nondestructive continuous indentation technique has been proposed to evaluate various strength concerning mechanical properties from the analysis of load-depth curve. In this study, quantitative residual stress estimation on API X65 welded joints for natural gas pipeline was performed by analyzing the variation of indentation loading curve by residual stress through a new proposed theoretical model. The residual stress from the indentation method was compared with that from the saw-cutting method.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.928-930
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• 2022

최근 취향 관심사를 기반으로 한 소모임 플랫폼 수요가 높아지듯, 대학 내외의 사회 전반에서 수준 높은 네트워킹에 대한 욕구가 강한 상황이다. 나아가, 교육 환경, 거주 지역, 개인의 성향 등의 변인들이 성장의 주요 발판이 될 인적 자원을 만드는 데에 지대한 영향을 끼친다는 점에서, 진입 장벽을 낮출 서비스에 대한 니즈가 존재한다. 한편, 기존의 플랫폼은 대학 동아리 및 소모임 활동을 분산적으로 취급하며 총괄하지 못한다. 따라서, 본 논문은 기존 플랫폼의 문제점을 개선한 메타버스 웹 플랫폼인 클러버스(Clubverse)를 소개한다. 이는 대학 내 동아리 간의 소통 및 외부 업체와의 연계를 제고하고 성장기회를 공평하게 분배해 변화에 대비할 수 있는 가능성을 지닌다.

• Journal of the Korean Institute of Gas
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• v.24 no.5
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• pp.39-46
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• 2020

This paper is considered about centerline segregation of API 5L steel used in pipeline. Mn/S, Nb and C were known as segregated elements in the centerline of pipe thickness. The Mn usually was accompanied by S consisting of long viscous shape. Microstructure of the centerline was composed of MnS and Nb/Ti indusions including oxide. The segregation effect in centerline region was analyzed by OM, SEM/EDS and micro Vickers hardness. The Mn, Nb and C are retarded elements in transformation from austenite to ferrite or martensite. These elements could derive a bainitic microstructure as a kind of martensite, which is different from difference and element segregation between in matrix and centerline derived from steel melting and heat treatment.

• Review of KIISC
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• v.12 no.2
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• pp.7-17
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• 2002

최근 급속도로 발전하고 있는 생체인식 분야는 상업적인 활성화와 이에 따른 사용자의 신뢰성 확보를 위해 서로 다른 생체인식 제품들의 상호호환성과 상호연동성을 고려하여 표준화된 생체인식 데이터 및 API에 대한 기술 개발을 하고 있다. 그리고, 사용자의 신뢰성 확보를 위해 생체인식 제품에 대한 성능 및 보안성 평가기술 개발을 위해 국내외에서 연구가 활발하게 진행되고 있다. 국외의 경우 ANSI, NIST, IBIA, EU, AfB, 등의 기관을 통해 생체인식 제품들에 대한 표준을 연구하고 있으며, BioAPI, BAPI, HA-API 등과 같은 기술표준과 보안기술표준인 X9.84 및 생체인식 데이터 형식에 대한 표준인 CBEFF를 발표하였다. 그리고, 독일의 GISA, 영국의 CESG와 NPL, 그리고 미국의 NIAP와 BFC 등은 생체인식제품에 대하여 성능평가 및 보안성 평가 연구를 추진 중에 있다. 국내의 경우 KSIA, KBA, TTA TC10/SG3, ETRI 등을 통하여 표준화 작업을 진행하고 있으며 KISA에서 국책과제인 'Biometric 인증시스템 보안성 평가기술 개발'을 통해 성능 및 보안성 평가기술을 개발하고 있다.

• TTA Journal
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• s.78
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• pp.69-76
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• 2001

생체인식 분야는 IT 분야의 보안기술과 함께 발전속도가 빠른 분야 중에 하나로 상업적인 활성화와 이에 따른 사용자의 신뢰성을 확보하는 것이 무엇보다 중요하다. 이에 따라 서로 다른 생체인식 제품들의 상호호환성과 상호연동성을 고려한 개술개발을 위해 표준화된 생체인식 데이터와 API를 개발할 필요성이 크게 증가하였다. 국외의 경우 ANSI, NIST, IBIA, EU(European Union), AfB등의 기관을 통해 생체인식 제품들에 대한 표준을 연구하고 있으며 BioAPI, BAPI, HA-API 등과 같은 기술표준과 X9.84, CBEFF 등과 같은 보안기술 표준을 발표하였다. 그러나 2000년까지 국내에서는 인식 알고리즘에 대한 연구만 일부 학계 및 연구기관에 의해 진행되고 있었으며 표준화에 대한 연구는 전무한 상태였다. 2001년부터 2월 KBA(Korea Biometrics Association, 생체인식협의회)의 발족을 기점으로 KBA와 KISDA(Korea Information Security Agency, 한국정보보호진흥원)를 중심으로 생체인식 표준화에 대한 연구가 활기를 띄기 시작했다.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.4
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• pp.435-442
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• 2002

It is difficult to access and share design data among heterogeneous CAD systems. Usually, different CAD systems exchange the design data using a neutral format such as IGES or STEP. A prototype CAD system which uses a geometric kernel and a commercial database management system has been implemented. The prototype system used the Open Cascade geometric kernel and the commercial object-oriented database ObjectStore. STEP provides the database schema. The database can be accessed from commercial CAD systems such as SolidWorks or Unigraphics. The data access module from a commercial CAD system is developed with the CAD system's native API, ObjectStore API functions, and ActiveX.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.67-73
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• 2011

One of the important topics to prepare the up-coming era of so-called ‘hydrogen economy’ is hydrogen transmission. Pipeline is conceivably the most economic way to consistently and safely transport a large amount of hydrogen over a long distance, which may be strongly requested in hydrogen economy era. As a good starting point for the purpose, one might wonder whether conventional API pipeline steels as designed for natural gas transmission can be used as the hydrogen pipeline materials or not. To answer the question, here we performed a series of micro-/nano-indentations together with tensile tests on the hydrogen-charged API X65, X70 and X100 steels having different strength level. In this paper, from the results of tensile tests, the hydrogen effects on the mechanical behavior in the API steels are systematically evaluated.

• Corrosion Science and Technology
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• v.17 no.3
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• pp.109-115
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• 2018

Electrical Resistance Welding (ERW) on a longitudinal seam-welded pipe has been extensively used in oil and gas pipelines. It is well known that the weld zone commonly suffers from grooving corrosion in ERW pipes. In this paper, the grooving corrosion performances of API X65 grade non-sour service (steel-A) and API X70 grade sour gas resistant (steel-B) steel electrical resistance welding pipelines were evaluated. The microstructure of the bondline is composed of coarse polygonal ferrite grains and several elongated pearlites. The elongated pattern is mainly concentrated in the center of the welded area. The grooving corrosion test and electrochemical polarization test were conducted to study the corrosion behavior of the given materials. A V-shaped corrosion groove was found at the center of the fusion zone in both the steel-A and steel-B ERW pipes, as the corrosion rate of the bondlines is higher than that of the base metal. Furthermore, the higher volume fraction of pearlite at the bondline was responsible for the higher corrosion rate at the bondline of both types of steel.

• Journal of the Korean Institute of Gas
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• v.5 no.3 s.15
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• pp.15-22
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• 2001

Reliability evaluation of welded structures by mechanical testing of weld heat-affected zones (HAZs) has become general practice throughout the world. HAZs of steel welded Joints show a gradient of microstructure from the fusion line to the unaffected base metal. This study is concerned a correlation between the microstructural change and the fracture characteristics in HAZs of both seam and girth welds of API 5L X65 pipeline steel, which is generally used for natural gas transmission pipelines in Korea. The focus in this study is the investigation of macroscopic fracture behavior of the various regions within HAZ. Changes in microstructure and toughness were observed using actual HAZ specimens. To evaluate the macroscopic toughness of actual HAZ, Charpy V-notch impact test and CTOD test were performed.

• Korean Journal of Metals and Materials
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• v.48 no.10
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• pp.875-883
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• 2010

This study assessed the Charpy impact properties of the heat-affected zones (HAZs) of API X80 linepipe steels containing complex oxides. Three types of steel were fabricated by adding Mg and $O_2$ to form complex oxides and their microstructures and Charpy impact properties were investigated. The number of complex oxides increased with the amount of excess Mg and $O_2$ that was included in the steels. Simulated HAZs containing a number of oxides showed a high volume fraction of acicular ferrite (AF) because the oxides acted as nucleation sites for AF, thereby leading to an improvement in the Charpy impact properties. According to a correlation study between the heat input, the volume fraction of the AF, and the Charpy impact properties, ductile fractures occurred predominantly when the fraction of the AF was 20% or higher; moreover, the Charpy absorbed energy was excellent at more than 100 J. These findings suggest that the improvement of the Charpy impact properties of the HAZs was associated with the active nucleation of AF in the oxide-containing steel HAZs.