• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.341-348
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• 2004

Recently deveoped HSS of POSCO and commerciallizing activities were introduced. 590DP, 590FB, 780TRIP. In this year, another three type of hot rolled AHSS will be developed and try to commerciallize with auto makers. 780FB, 780DP and 980CP. We have future plan to develope ultra high strength steels 980TR, 1170CP.

• Journal of the Korean Geosynthetics Society
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• v.6 no.3
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• pp.31-37
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• 2007

A steel strip reinforcement for the reinforced earth structures was recently developed to substitute the existing ribbed steel strip reinforcement. The developed reinforcement consists of the punched steel strip having dimension of 65mm width and 4.5mm thickness and the transverse steel bar for increasing bearing resistance. The punched steel strip has holes of 11mm diameter in every 50cm spacing with 2mm rising around perimeter of the holes. A series of shear friction tests and pull-out tests were carried out to evaluate the friction properties of the developed reinforcement. The results of these tests show that pull-out resistance of the developed reinforcement was significantly increased when the transverse steel bars are installed in the punched steel strip.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.481-492
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• 2018

The steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine two inhomogeneous materials. In general, the steel plate is assembled by welding an existing composite beam. In this study, the SPC beam was composed of folding steel plates and concrete, without a headed stud. The folding steel plate was assembled by a high strength bolt instead of welding. To improve the workability in a field construction, a hat-shaped cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode to analyze the flexural strength of the SPC beam using a cap as the shear connector. Five specimens with shear connector types, protrusion length, and different thickness of steel plates were constructed and tested. The experimental results were analyzed through the relationship between the shear strength ratio and flexural strength in KBC 2009. The test results showed a shear strength ratio of more than 40 %. In the case of using a cap-like specimen as the shear connector, the flexural strength was 70% of the value calculated as a fully composite beam. In addition, the cap showed a smaller shear strength than the stud, but the cap served as a shear connection. When the thickness of the steel plate was taken as a variable, the steel plate exhibited a bending strength of approximately 70% compared to a fully formed steel plate, and exhibited similar deformation performance. Local buckling occurred due to incomplete composite behavior, but local buckling occurred at a 5% higher strength for a relatively thick steel plate. The buckling width also decreased by 15%.

• Journal of the Korean Institute of Gas
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• v.14 no.6
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• pp.38-43
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• 2010

According to the lack of resources and the stringency of environmental regulations, a study of the high strength thin plate sheet steels for automobile have been become an important issue for automobile industry. However, the problem of hydrogen embrittlement of high strength sheet steels was concerned with the degradation of mechanical properties. Therefore, we studied the hydrogen behavior of surface layers of 590MPa DP sheet steels on development using by relationship the microstructure of subsurface and the distribution of micro hardnesses. Hydrogen was charged into the specimens using by the cathodic electrolytic method. The behavors of under surface layers were investigated by the observation of microstructures and the micro vickers hardness test with the amount of hydrogen charging with hydrogen charging conditions.

• ICROS
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• v.15 no.1
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• pp.37-43
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• 2009

철강제조공정에서 강판을 만드는 공정이 압연이다. 압연공정은 연속주조 공장에서 생산되는 Steel Slab, Bloom, Billet등의 반제품을 높은 온도로 재 가열하고 물리적인 힘을 가해 압연하는 열간압연(이하 열연)과 열연으로 얇아진 강판을 열을 가하지 않고 냉각상태에서 압연하는 냉간압연으로 나뉜다. 본 원고에서는 열연 공정의 가열로 온도제어에 적용한 MFA(Model Free Adaptive Controller)를 소개하고자 한다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.1-12
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• 2017

In this study, It was purpose to provide preliminary data for extension of the applicability of deep corrugated steel plate composite members by steel grade and shear reinforcement method. From the result of flexural test on deep corrugated plates composite members using GR40 and SS590, positive moment capacity was increased about 28% by SS590 steel. But to change steel grade was proved to have insignificant effects for increasement of negative moment capacity. In the moment test result of same overlapping length, Increasement rate of positive and negative moment capacity was not significantly improved by increasing the number of bolt. It was estimated to be due to the characteristics of bolt connection such as distance between centers of bolts, edge distance of bolt. In the test result on the spacing of shear reinforcement, positive moment capacity was increased and deformation of negative moment was reduced as the distance decrease. In the test result on the shape of shear reinforcement, positive and negative moment resistance was increased about 2% ~ 7% by U shaped shear reinforcement. In conclusion It was estimated that moment capacity of deep corrugated steel plate composite members are depend on steel grade of deep corrugated steel plate, spacing of shear reinforcement and reinforcing bar.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3A
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• pp.149-160
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• 2012

Corrugated steel plates have several advantages such as high resistance for shear without stiffeners, minimization of welding process, and high fatigue resistance. To take advantage of these benefits, several researchers have attempted to use corrugated steel plate as a web of I-girders. The lateral-torsional buckling is the major design aspect of such I-girders. However, lateral-torsional buckling of the I-girder with corrugated steel webs still needs to be investigated especially for a real loading condition such as non-uniform bending. This paper investigated the lateral-torsional buckling strength of the I-girder with corrugated steel webs under linear moment gradient by using finite element analysis. From the results, it was found that the buckling behavior of the I-girder with corrugated steel webs differed depending on the number of periods of the corrugation. Also, a simple equation for the moment gradient correction factor of the I-girder with corrugated steel webs was suggested. The inelastic lateral-torsional buckling strength of the I-girder with corrugated steel webs was then discussed based on current design equations for ordinary I-girders and the results of finite element analysis.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1483-1484
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• 2011

상용 뮤-메탈, 방향성 및 무방향성 규소강판을 출발 재료로 하여 두께 0.1 mm의 차폐재 3 종류를 제조하여 전력 케이블 인근자계 차폐 효과를 조사하였다. 3상 전류일 때, 차폐재 위치의 자기장이 100 ${\mu}T$ 정도이면 뮤-메탈이(SF < 0.1) 가장 효과적이었고, 500 ${\mu}T$ 이상이면 규소강판이(SF 0.3~0.4) 더 효과적이었다. 또한, 안쪽에 방향성 규소강판, 바깥쪽에 뮤-메탈을 함께 둘러쌀 경우 500 ${\mu}T$까지도 SF를 0.1 이하로 할 수 있었다. 한편, 단상 전류에서는 고투자율 소재의 적용은 오히려 자기장을 증가시키는 결과를 보였다. 이상의 결과는 자기장 강도 H의 크기에 따라 각 소재의 투자율 우열이 서로 다른 점과 이로 인해 차폐재 내에 유도되는 자기장 벡터와 원래의 자기장 벡터의 상호 상쇄 및 중첩 작용으로 설명할 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.305-314
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• 2018

The steel-plate concrete composite beam is composed of a steel plate, concrete and a shear connector to combine the two inhomogeneous materials. In general, the steel plate is assembled by welding an existing composite beam. In this study, a new steel-plate concrete composite (SPCC) beam was developed to reduce the size of the shear connector and improve its workability. The SPCC beam was composed of folded steel plates and concrete, without any shear connector. The folded steel plate was assembled with high strength bolts instead of welding. To improve the workability in field construction, a hat-shaped cap was attached in the junction with the slab. Monotonic two-point load testing was conducted under displacement control mode. The flexural strength of the SPCC beam specimen was calculated to be 76% of that of the complete composite beam by using the plastic stress distribution method and strain compatibility method. The cap acted as the stud and accessory. The synthesis rate could be increased by controlling the gap of the cap, and the bending performance could be evaluated by using the strain fitting method considering the synthesis rate of the SPCC beam.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.6
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• pp.479-484
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• 2017

In this paper, finite element analysis of Steel-Concrete panel(SCP) was conducted considering the local buckling behavior and the optimized design of shear studs arrangement was studied by comparing with design guidelines. If the spacing of the studs of SCP is widened, it is easy to be manufactured and the weight fo members become lighter. On the other hand, the steel plate would be vulnerable to the local buckling behavior. Therefore, the guidance and design of SCP limit the maximum spacing of the studs to prevent the development of shear cracks and local buckling, however this is based on the design criteria of the other composite structures. Parameter studies with changes in stud spacing on steel plate and SCP are conducted and the obtained result was compared with values given in design guidelines.