• 복합신소재구조학회 논문집
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• 제4권3호
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• pp.22-29
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• 2013

In recent years, the construction of high-rise buildings are promoted. According to these, there are many needs about new technologies to strengthen the building performance and high-strength steel is regarded as one of these for promoting building performance. In Korea, high-strength steels which stress are over 600MPa are on market and in aborad, super high-strength steels over 1000MPa are developing and they expected to promote the building performance. But there are still doubts about applying high-strength steel members because of size effect and worry of brittle fracture. In this reports, we propose results of performance and analysis tests for use with general steel. We propose the characteristic of high-strength steels first and next the results of performance test to show they satisfy the performance that designers expect. And last, we compare the results of test and analysis for acquire the alanysis reliability in non-linear analysis with high-strength steels.

• Corrosion Science and Technology
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• 제10권2호
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• pp.47-51
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• 2011

Main issues in the automotive industry are the reduction of vehicle body weight for energy savings and improvement of crashworthiness for passenger safety. In order to address both these issues, there has recently been increasing application of galvannealed advance high strength steel (GA AHSS) sheets for automobiles. However, GA AHSS sheets have some surface defects such as coating bare spots due to the addition of solid-solution strengthening elements, which result in the deterioration of the galvannealing reaction. In this study, the effects of galvannealed manufacturing conditions on surface and mechanical properties, resistance spot weldability on a laboratory scale, and GA 980 MPa steel sheets produced by commercial continuous galvannealing line (CGL) were investigated.

• Corrosion Science and Technology
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• 제10권5호
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• pp.157-161
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• 2011

HY-Galume is a brand name of 55%Al-Zn coated steel sheets produced by Hyundai HYSCO. Heavy gauged HY-Galume having thickness around 2 millimeters is used as a steel casing for the electrical distribution panel in the construction market. It requires a strict surface quality because it is used indoors. In this paper, several troubleshooting experiences in producing heavy gauged HY-Galume are proposed.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.281-281
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• 2012

We could confirm the results such as excellent anti-corrosion compared to chromate, conductivity, chemical resistance and detergent resistance as the result of analysis of various characteristics of the galvanized steel coated with organic-inorganic developed in this research.

• Corrosion Science and Technology
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• 제10권5호
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• pp.162-166
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• 2011

Effects of chemical compositions and manufacturing conditions on mechanical properties and microstructures were investigated in order to obtain galvannealed high strength dual phase steel sheets with superior mechanical properties and coating properties. An intercritical annealing between Ac1 and Ac3 was conducted to produce the DP (dual phase) steel sheets, followed by quenching to room temperature. The purposes of Al addition are to reduce the iron oxidation with chemical composition (Si, Mn etc.) and to improve the wettability by liquid zinc. The present study will focus on the characterization for making dual phase steel sheets and enhancing the galvanizability of Al added DP steel sheets about continuous annealing line in CGL.

• Applied Microscopy
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• 제43권2호
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• pp.81-87
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• 2013

The influence of carbide formation on mechanical properties has been investigated in carburized steels. Through controlled diffusion and precipitation processes, the morphologies of carbides could be changed and then fine, networked, and spherical shapes at carburized layers were obtained. These morphological changes affected tensile and bending fatigue properties of the steel. The fine and the spherical carbides acted as resistance sites against crack propagation, which improved the mechanical properties. However, the networked carbides deteriorated the properties because the cracks propagated along the boundaries of them. These results indicate that the morphological control of carbides is one of important keys to improve the mechanical properties.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.408-411
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• 2002

Effect of in-situ vibration on the properties of A-grade steel SMA weldment has been investigated. Welding was performed on the steel fixed at the experimental jig under the mechanical vibration of a given frequency. The applied frequency varied from 39 to 43.5 Hz (harmonic frequency). For weldments formed under the vibration with a sub-harmonic frequency, both the columnar width of the weld metal and the prior austenite grain size of the HAZ near the fusion line clearly decreased. This indicates that the vibration increase the cooling rate after welding. Vibration effect was also found at the weld metal formed at the center region of the weldment. The weld metal showed liner microstructure both in columnar zone and in equiaxed zone with thinner grain boundary ferrite. However mechanical properties of the weld metal did not exactly follow the microstructural changes developed under the vibration. The weld metal formed under the vibration revealed higher yield and tensile strength but lower ductility and impact toughness, compared with the conventional weld metal.

• 한국경영과학회지
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• 제17권1호
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• pp.65-65
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• 1992

Recently many organizations have attempted to build hypermedia systems to expand their working areas to internet-based virtual work places. It is thus important to manage corporate hypermedia documents effectively. Metadata play a critical role for managing these documents. This paper identifies metadata roles and components to build its schema. Furthermore a meta-information system HyDoMiS(Hyperdocument Meta-information System) is proposed by the use of this metadata schema. HyDoMiS performs three functions metadata management search and reporting The metadata management function is concerned with workflow document and database. The system is more likely to help implement and maintsain hypermedia information system effectively.

• 실천공학교육논문지
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• 제12권1호
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• pp.203-212
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• 2020

본 연구는 제철산업학과 2015년에서 2019년 2월 졸업생 총 356명 중 취업자 244명을 대상으로 연구하였다. 졸업생의 주요 취업처인 포스코의 취업율은 67.7%, 현대제철은 23.8%, 포스코 계열사 13.1%, 현대제철 계열사는 8.5%로 조사되었다. 각 분야별 취득한 자격증은 금속 분야 53.1%, 기계 분야 39.8%, 기타분야 7.1%이다. 국가자격증의 종류와 분포는 포스코의 경우, 기계정비 산업기사, 제선 기능사 및 제강 기능사 순이며, 현대제철은 제강기능사, 제선 기능사 및 기계정비 산업기사 순으로 조사되었다. 이 외 기타분야의 자격증 중 산업안전 산업기사 국가자격증을 비중이 높은 것으로 나타났다. 취업자 1인당 평균 국가자격증의 수는 포스코 5.06개, 포스코 계열사 5.35개, 현대제철 5.29개, 현대제철 계열사 4.73개이다. S-오일, 한국전력, 풍산금속 등 기타 취업처의 평균 국가자격증 수는 2.51개로 나타났다. 본 연구를 통해 조사한 전공 관련 국가 자격증이 입사시 직무에 필요한 인재를 채용하고, 직무에 적합한 전공자를 발굴하는 데에 있어서 주요한 평가자료로 사용 된다는 결론을 얻었다.

• 한국레이저가공학회지
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• 제2권3호
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• pp.11-18
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• 1999

This paper describes the weldability of carbon steel and stainless steel using 5㎾ $CO_2$ laser system with nearly multi-mode beam and a parabolic focusing mirror. In the laser welding of steels, major welding parameters are focal point, travel speed, beam power, shield gas and gap tolerance, etc.. Two kinds of gases(Ar, He) were used as a assist gas and supplied through the external nozzle. It is very important for optimum condition to remove plasma plume which absorbs laser beam and to obtain deep penetration and sound weld bead. Bead-on-plate welding tests were carried out for the experiments. Penetration data were obtained with various welding parameters and the effects of welding parameters were discussed. Butt welding tests were performed with various conditions. Only the optimum laser parameters assured good weld quality As a result of this study, We achieve the fundamental weldabilities using a high power $CO_2$ laser for carbon steel and stainless steel.