• IE interfaces
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• v.6 no.2
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• pp.117-131
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• 1993

A job sequencing model is developed and its computer system is tested for processing cold-rolled coils in Tandem Cold Mills(TCM) at the Pohang Iron and Steel Company. Given coils waiting to be processed, this system generates a sequence of jobs satisfying operational constraints for the TCM process. We formulate the problem as a constraint satisfaction problem and employ the backtracking technique combined with looking ahead features in order to generate a feasible solution within a reasonable time. Our system is implemented in C language on 80486-based IBM PC. Some tests based on the real data show that our system is adequate with respect to search time and that it consistantly generates a good feasible solution.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.174-174
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• 2003

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.31-32
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• 2007

자동차 도장 전처리 공정 중 인산염처리는 소지와 도장층 사이의 밀착성을 향상시키고, 강판의 내식성을 향상시키는 목적으로 행하여진다. 인산염 조직이 치밀하게 형성되지 못하면 도장층 박리 등의 불량이 발생할 수 있다. 본 연구에서는 전기로재 BAF(Batch Annealing Furnace) 냉연강판의 인산염처리 특성에 대한 분석 및 개선안 도출 과정을 서술하였다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.521-524
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• 2008

Effect of prior deformation on the sliding wear of the ultra-fine grained (UFG) ferrite-martensite dual phase (DP) steel was investigated. The UFG DP steel was fabricated by the ECAP and subsequent intercritical annealing. The steel was cold rolled before the wear test, and the effect of the prior deformation on the wear was examined. The wear tests were carried out at various loads against a bearing steel ball. The wear rate of the UFG DP steel that did not experience the prior deformation was higher than that of the coarse-grained (CG) DP steel, because of more severe surface shear deformation. The wear rate of the specimens with prior deformation was much higher than that of the specimen without prior deformation. The deformed CG DP specimen showed higher rate than the deformed UFG DP specimen, and the rate-variation of the CG DP steel was much bigger under the same test condition.

• Korea Trade Review
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• v.44 no.5
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• pp.127-142
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• 2019

As Korea's steel industry exports 38 percent of its total steel production, the future management environment of the steel industry will change depending on the outcome of the FTA negotiations. The overall industrial structure of the domestic steel industry depends on the rules of origin, which are directly linked to the effect of concessionary tariffs. Therefore, negotiations on rules of origin are as important as tariff liberalization for Korea's steel industry. Korea's cold-rolled and plated companies are expected to be negatively affected as the country of origin standards of steel products have not considered the steel production processes in Korea. In future FTA talks, the country of origin rules should be agreed on a change of tariff classification basis. This result would secure a stable export market through increased predictability of steelmakers and reduce the risk of increased costs of oil and intangible products. In addition, the government should consider the structure of domestic supply and demand so that it does not impose constraints on the change of tariff classification. Finally, participants in the negotiations should consider the opinions of the domestic steel industry.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.277-287
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• 1994

The effect of grain size on the tensile properties and fatigue behavior of austenitic high Mn steel has been investigated. The recrystallized austenite grain size of the cold rolled high Mn steel was increased as the annealing temperature increased from $600^{\circ}C$ to $1000^{\circ}C$. Larger austenite grain size decreased the yield strength and the tensile strength, and increased the uniform elongation due to transformation of some austenite into twins or E-martensite phase during deformation. Austenite grain refinement increased the tendency to form dislocation cells, instead. The specimen annealed at $1000^{\circ}C$ with large grain size showed lower fatigue crack propagation rate in low ${\Delta}K$ region due to rougher fracture surface caused by formation of deformation twins during fatigue at the crack tip region.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.91-97
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• 2000

Anisotropic work hardening of cold rolled low carbon steel sheets is studied. The experiments consist of two stage tensile prestraining and tensile tests. At the first prestraining, steel sheets are streteched along the rolling direction by 3% and 6% tensile strains. The second prestrains are at 0${\cric}$, 30${\cric}$, 60${\cric}$to the rolling directions by varying degrees. Tensile tests are performed on the specimens cut from the sheets after the two stage prestraining. A theoretical framework on anisotropic hardening is proposed which includes Hill's quadratic yield function, ziegler's kinematic hardening rule, and Kim and Yin's assumption on the rotation of orthotropy axes. The predicted variations of R-values with second stage tensile strain are compared with the experimental data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.629-632
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• 1995

The formability of an automobile body panel is very important. So, we performed an annealing condition change for the development of annealing condition with temperature, atmospheric gas and the annealing cycle. Formability was changed under the influenced of the mechanical properties of steel sheet for the automobile body panel. Therefore, ot os important in the BAF(Batch annealing furnace) annealing process. Because mechanical properties were decided on the heat treatment method of the coil. So, we tested the development of mechanical properties according to the heat treatment method at the annealing furnace using the Ax atmospheric gas and the HNx atmospheric gas. As a result of several investigations, we confirmed the following characteristics ; mechanical properties change under the influence of the annealing cycle and atmospheric gas.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.2
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• pp.108-114
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• 1998

Development on the mechanical properties of steel sheet for the automobile body panel is very important in the BAF(Batch annealing furnace) annealing process. Because of the heat treatment method in the BAF, mechanical properties was decided on the heat treatment method of the coil. So, we tested on the development of mechanical properties according to heat treatment method at the annealing furnace using the Ax(H$_2$75%, $N_2$25%) atmospheric gas and the HNx(H$_2$4%, $N_2$96%) atmospheric gas. As a result of several investigations. We confirmed the following characteristics ; mechanical properties was changed under the influence of the annealing cycle, the heat treatment method and the atmospheric gas. And, elongation in the HNx BAF was better than the Ax BAF. Finally, most important thing in the BAF is using of proper annealing cycle in order to get a good quality.

• Journal of the Korean institute of surface engineering
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• v.30 no.5
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• pp.310-319
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• 1997

The purpose of this study is to investigate the effect of the specific alloying elements in steel such as Cr, Ni and Cu, and surface roughness of substrate with two different FCS temperature zones in the CAL process on the phosphatability of the cold-rolled sheet used for the drum in order to improve the zinec phosphating property. Phosphatability is dependent of the surface oxide and roughness on the substrate and can be indirectly improved by increasing surface roughness of the steel sheet. Basically, in order to obtain the good phosphatability, the low concentration of the retained elements such as Cr, Ni and Cu among the steel alloy elements should be required. Phosphatability of substrate with high concentration instead of the retained elements and surface roughness, however, can be effectively improved instead of low FSC temperature.