• 콘크리트학회논문집
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• 제26권6호
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• pp.771-778
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• 2014

본 연구에서는 하이브리드 강섬유로 보강된 초고성능 콘크리트(UHPC)의 휨거동 특성을 파악하고자 하였다. 부피비 1.5%의 하이브리드 강섬유를 혼입하여 철근비가 0.02 이하인 부재의 실험을 통해 주요 휨거동 특성을 파악하였다. 본 연구결과는 추후 UHPC의 휨강도 산정 모델링에 실제적인 기초실험자료로 활용될 수 있을 것으로 사료된다. 하이브리드 강섬유 보강 UHPC는 균열제어에 효과적이며, 연성지수는 9.2~15.2 범위에 분포하고 있어 우수한 연성거동 특성을 나타낸다. 또한, 순수 휨 구간 내에 스터럽을 배근한 부재의 휨강도는 스터럽을 배근하지 않은 부재의 휨강도와 유사하며, 이 실험연구의 150 mm 간격 정도의 스터럽 배근은 강섬유 배열 및 휨강도에 영향을 미치지 않는다고 판단된다.

• 토지주택연구
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• 제2권1호
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• pp.47-52
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• 2011

현재 토목 및 건축구조에서 고성능 고강도 강에 대한 수요가 증가함에 따라 고성능 재료개발의 필요성이 증대되고 있다. 특히 초고층 건물과 장경간을 가지는 구조에서는 고강도, 고인성, 우수한 용접성 등이 요구된다. 이에 따라 현재 국내에서는 600MPa 급 강재의 개발이 진행 중에 있다. 그러나 고강도 강재는 일반 강재와는 전혀 다른 기계적 특성을 갖고 있다. 그러므로 고강도 강재를 구조물에 적용하기 위해서는 비탄성영역에서의 거동이 일반 강재와 동등한가를 확인해야 한다. 본 연구에서는 600MPa급 원형 강관의 기둥 및 보부재 실험을 통해 구조적 거동을 파악하였다. 각각 3개의 기둥 및 보 실험이 수행되었으며, 현행설계규준과의 적합성을 평가하였다.

• Steel and Composite Structures
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• 제17권1호
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• pp.105-121
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• 2014

A fundamental limitation of steel structures is the decrease in their load-bearing capacity at high temperatures in fire situations such that structural members may require some additional treatment for fire resistance. In this regard, this paper evaluates the structural stability of fire-resistant steel, introduced in the late 1999s, through tensile coupon tests and proposes some experimental equations for the yield stress, the elastic modulus, and specific heat. The surface temperature, deflection, and maximum stress of fire-resistant steel H-section columns were calculated using their own mechanical and thermal properties. According to a comparison of mechanical properties between fire-resistant steel and Eurocode 3, the former outperformed the latter, and based on a comparison of structural performance between fire-resistant steel and ordinary structural steel of equivalent mechanical properties at room temperature, the former had greater structural stability than the latter through $900^{\circ}C$.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.134-135
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• 2006

Ancorsteel 4300, a high performance Cr-Si-Ni-Mo steel, was unveiled two years ago as the first in a series of powder metallurgy alloys that will simulate wrought steel compositions. Advantages of this alloy include good compressibility, high hardenability, and excellent dimensional stability. More important, however, is that this alloy has the ability to be effectively sintered at $1120^{\circ}C$ and maintain oxygen contents below 500 ppm. This unique blend of performance and processing capabilities provides static and dynamic properties that exceed those of conventional powder metallurgy alloys and approach wrought gearing materials. A second Cr-Si-Ni-Mo alloy has now been developed that offers complimentary performance levels at a lower Mo content. This manuscript reviews properties of the two chromium steels with comparisons to traditional sinter-hardened and heat-treated powder metallurgy alloys.

• 한국정밀공학회지
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• 제19권4호
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• pp.154-160
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• 2002

Powder metallurgy(P/M) process has been used for the production of high performance high-speed steels. P/M high speed steel has more uniform and fine microstructure than those of conventional wrought products. Therefore, it offers distinct advantages over conventional tool steels. The superior uniformity of composition and fine microstrucure lead to excellent toughness and less distortion during heat treatment, which in turn can reduce total grinding costs and provides other benefits, such as uniform hardness and increased tool life. From these reasons, milling, hole machining, broaching, and gear manufacturing tools are major applications of P/M high-speed steels. In this research, we evaluated tool wear of flat endmill which is made of P/M high-speed steel from the view point of cutting tool performance.

• 한국지열·수열에너지학회논문집
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• 제19권3호
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• pp.14-22
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• 2023

Steel-pipe civil structures, including steel-pipe energy piles and cast-in-place piles (CIPs), utilize steel pipes as their primary reinforcements. These steel pipes facilitate the circulation of a working fluid through their annular crosssection, enabling heat exchange with the surrounding ground formation. In this study, the cooling performance of a ground source heat pump (GSHP) system that incorporated steel-pipe civil structures was investigated to assess their applicability. First of all, the thermal performance test was conducted with steel-pipe CIPs to evaluate the average heat exchange amount. Subsequently, a GSHP system was designed and implemented within an office container, considering the various types of steel-pipe civil structures. During the performance evaluation tests, parameters such as the coefficient of performance (COP) and entering water temperature (EWT) were closely monitored. The outcomes indicated an average COP of 3.74 for the GSHP system and the EWT remained relatively stable throughout the tests. Consequently, the GSPH system demonstrated its capability to consistently provide a sufficient heat source, even during periods of high cooling thermal demand, by utilzing the steel-pipe civil structures.

• Earthquakes and Structures
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• 제13권5호
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• pp.485-496
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• 2017

The behavior of 8 steel reinforced high-strength concrete (SRHSC) columns, which comprised of four identical columns with cross-shaped steel and other four identical columns with square steel tube, was investigated experimentally under cyclic uniaxial and biaxial loading independently. The influence of steel configuration and loading path on the global behavior of SRHSC columns in terms of failure process, hysteretic characteristics, stiffness degradation and ductility were investigated and discussed, as well as stress level of the longitudinal and transverse reinforcing bars and steel. The research results indicate that with a same steel ratio deformation capacity of steel reinforced concrete columns with a square steel tube is better than the one with a cross-shaped steel. Loading path affects hysteretic characteristics of the specimens significantly. Under asymmetrical loading path, hysteretic characteristics of the specimens are also asymmetry. Compared with specimens under unidirectional loading, specimens subjected to bidirectional loading have poor carrying capacity, fast stiffness degradation, small yielding displacement, poor ductility and small ultimate failure drift. It also demonstrates that loading paths affect the deformation capacity or deformation performance significantly. Longitudinal reinforcement yielding occurs before the peak load is attained, while steel yielding occurs at the peak load. During later displacement loading, strain of longitudinal and transverse reinforcing bars and steel of specimens under biaxial loading increased faster than those of specimens subjected to unidirectional loading. Therefore, the bidirectional loading path has great influence on the seismic performance such as carrying capacity and deformation performance, which should be paid more attentions in structure design.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.133-136
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• 2007

In this work, 3-dimensional, non-isothermal numerical simulation was performed to analyse the effects of contact resistance and electric conductivity of GDL on the fuel cell performance. For numerical simulation contact resistance of Carbon and Stainless steel was measured. The simulation results reveal that 10 times change of electric conductivity leads only 6.5% decrease of PEMFC performance. But stainless steel which has high contact resistance decrease fuel cell performance over 25% at a high current density region than carbon. This results show that suitable Surface treatment technology is needed for metal bipolar plate, especially stainless steel.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.184-186
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• 2012

In this work, 3-dimensional, non-isothermal numerical simulation was performed to analyse the effects of contact resistance and electric conductivity of GDL on the fuel cell performance. For numerical simulation contact resistance of Carbon and Stainless steel was measured. The simulation results reveal that 10 times change of electric conductivity leads only 6.5% decrease of PEMFC performance. But stainless steel which has high contact resistance decrease fuel cell performance over 25% at a high current density region than carbon. This results show that suitable Surface treatment technology is needed for metal bipolar plate, especially stainless steel.

• 자원리싸이클링
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• 제24권3호
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• pp.66-75
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• 2015

상대적으로 제조공정이 짧아 환경 및 경제적 이점을 갖는 비정질강섬유(AF)를 길이 및 혼입률을 변화하여 휨성능을 평가와 더불어 기존의 일반강섬유(HF)와의 비교분석을 실시하였다. 섬유의 길이는 10 mm, 20 mm, 30 mm, 및 혼입률은 0.3%, 0.6%로 변화를 주어 실험을 진행하였다. 비정질강섬유(AF의 경우 비중은 일반강섬유(HF)와 거의 동일한 값을 가지나 겉보기부피는 약 2배정도 커서 같은 혼입률에서 투입되는 섬유의 개수는 훨씬 증가되어 배합설계에서 주의를 할 필요가 있다. 실험결과 휨강도의 영향은 섬유의 길이 및 혼입률이 증가할수록 강도의 증가를 보였으며, 일반강섬유(HF)보다 크게 나타났다. 특히 최대하중부근에서의 에너지소산능력이 뚜렷하게 증가하여 잔류하중단계에서의 급격한 감소에도 불구하고 일반강섬유(HF)와 거의 유사한 잔류강도 및 에너지소산능력을 보여주었다. 콘크리트 균열 후 파괴진행단계에서는 섬유의 인발저항에 의한 균열진행이 아닌 섬유의 파단에 의한 강도의 급격한 감소를 보여준 것으로 판단된다.