• Journal of the Korean Society for Heat Treatment
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• v.17 no.5
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• pp.283-292
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• 2004

The effects of the annealing parameters on microstructures were examined in a cold-rolled high strength steel containing 0.1% C, 0.5% Si, 1.5% Mn, and 0.04% Nb. It was impossible to avoid martensite in the microstructure even though the continuous annealing parameters were controlled. This indicates that the alloying elements such as silicon and manganese contributing to manganese equivalent($Mn_{eq}$) should be reduced to produce the ferrite-pearlite microstructure for the solid solution and precipitation hardened steel. It was found that a decrease in the rapid cooling temperature to $520^{\circ}C$ was effective to change the microstructure from ferrite-martensite to ferrite-pearlite-martensite. Typical dual-phase properties exhibiting a low yield ratio and a continuous yielding behavior were obtained when the rapid cooling temperature was in the range of $680^{\circ}C$ to $600^{\circ}C$. The critical volume fraction of martensite for the typical properties of dual-phase steel was about 11 percent.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.530-535
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• 1999

In recently, annealing process of cold rolled sheet tend to change to continuous annealing process for improving quality, saving yield. In the meantime as demand for various kind and small lot of products has been increasing, batch annealing has been appreciated for its small restriction for the operation. So, we tested on the effect for the proper heating temperatures, heating time of cycle, cooling time and total cycle time in this annealing process of hi tensile strength steel for automobile. As a result of several investigation. we confirmed for the following characteristics; In this process, we knew that 68$0^{\circ}C$ is suitable for this heating temp. cycle heating time of 38 Hr, cooling time of 31 Hr and total cycle time of 70 Hr. Still more, we could know that it is proper for cold rolling before annealing to be managed by 7 pass because of the act on high pressure.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.8
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• pp.91-99
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• 1994

Damage induced by Si ion implantation and its annealing behavior during rapid thermal annealing were investigated by cross-sectional TEM (transmission electron microscopy) and RB ( Rutherford backscattering) spectrum. 150keV and 50keV Si ions were implanted in Si (100) at room temperature with doses of 2${\times}10^{15}cm^{-2}$. And 100keV Si ions were implanted in Si with doses from 1${\times}10^{14}cm^{-2}$. A variety of damage structures were generated by Si ion implantation such as continuous amorphous layer extending to the surface buried amorphous layer and damage clusters. Damage clusters are annealed out at the lower annealing temperature of 550 $^{\circ}C$. However, event at the temperature of 110$0^{\circ}C$ end of range loops remain in the original lower amorphous/crystal interface in the case of continuous and buried amorphous layer formation. Extended defects in the shape of zipper dislocations are also observed at the middle of the recrystallized region in the buried amorphous layer.

• Journal of the Korean Vacuum Society
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• v.2 no.4
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• pp.468-473
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• 1993

Damages on Si substrate induced by Ar ion implantation and it annealing behavior during rapid thermal annealing were investigated by the cross-sectional TEM (transmissin electron microscopy), RB(Rutherfordbackscattering) spectra an dthermal wave (TW) modulation reflectance methods. Continuous amorphous layer extending to the surface were generated by Ar ion implantation for higher doses than 1 $\times$1015cm-2. The recrystallization of the amorphous layer prodeeded as the annealing temperature increased . However the amorphous /crystal interfacial undulations caused the micro twins and damage clusters. Damage clusters generated by lower doses than 1 $\times$1015 cm-2 disappeared slowly as the annealing temperature increased, but even at 110$0^{\circ}C$ a few damage clusters still remained.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1512-1518
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• 2004

Rescaled Simulated Annealing (RSA) has been adapted to solve combinatorial optimization problems in which the available computational resources are limited. Simulated Annealing (SA) is one of the most popular combinatorial optimization algorithms because of its convenience of use and because of the good asymptotic results of convergence to optimal solutions. However, SA is too slow to converge in many problems. RSA was introduced by extending the Metropolis procedure in SA. The extension rescales the state's energy candidate for a transition before applying the Metropolis criterion. The rescaling process accelerates convergence to the optimal solutions by reducing transitions from high energy local minima. In this paper, structural optimization examples using RSA are provided. Truss structures of which design variables are discrete or continuous are optimized with stress and displacement constraints. The optimization results by RSA are compared with the results from classical SA. The comparison shows that the numbers of optimization iterations can be effectively reduced using RSA.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.3
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• pp.44-53
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• 2007

Forming central warehouses for a number of stores can save costs in the continuous review inventory model due to economy of scale and information sharing. In this paper, transportation costs are included in this inventory model. Hence, the tradeoff between inventory-related costs and transportation costs is required. The main concern of this paper is to determine the number and location of central warehouses. Transportation costs are dependent on the distance from several central warehouses to each store. Hence, we develop an efficient simulated annealing algorithm using distance-based local search heuristic and merging heuristic to determine the location and the number of central warehouses. The objective of this paper is to minimize total costs such as holding, setup, penalty, and transportation costs. The performance of the proposed approach is tested by using some computational experiments.

• Corrosion Science and Technology
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• v.7 no.1
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• pp.1-5
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• 2008

The gas atmosphere in continuous annealing and galvanizing lines alters both composition and microstructure of the surface and sub-surface of sheet steel. The formation and morphology of the oxides of alloying elements in High Strength Interstitial Free (HS-IF), Dual Phase (DP) and Transformation-Induced Plasticity (TRIP) steels are strongly influenced by the furnace dew point, and the presence of specific oxide may result in surface defects and bare areas on galvanized sheet products. The present contribution reviews the progress made recently in understanding the selective formation of surface and subsurface oxides during annealing in hot dip galvanizing and conventional continuous annealing lines. It is believed that the surface and sub-surface composition and microstructure have a pronounced influence on galvanized sheet product surface quality. In the present study, it is shown that the understanding of the relevant phenomena requires a combination of precise laboratory-scale simulations of the relevant technological processes and the use of advanced surface analytical tools.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.616-619
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• 1996

This paper presents the configuration methodology of Distributed Control System(DCS)s for process plant and their performance evaluation. Performance evaluation is specified both in terms of operational and installation aspects of system. In order to evaluate performance criteria of operational aspect, a simulation method is proposed. Modeling of system components including process computer, database, process controllers and LANs, etc, is implemented for simulation. Based on these characteristics, different system configurations are evaluated and compared through results about evaluation criteria in order to select the best DCS for particular process. The results, in abbreviated form, of the performance evaluation of DCS controlling a CAL(Continuous Annealing Line) plant of iron process are presented.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.184-186
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• 2002

The evolution of texture and microstructure during warm rolling and subsequent annealing in aluminium 3004 alloy sheet was investigated by X-ray texture measurements and microstructure observations. Warm rolling at 250$^{\circ}C$ led to the development of strong through thickness texture gradients with shear textures at the surface layer and a regular rolling texture in the center of the sheets. FEM simulations indicated that these texture gradients are caused by pronounced strain gradients throughout the sheet thickness. Upon recrystallization annealing, in the sheet center the characteristic cube-recrystallization texture developed, while in the surface layers with a pronounced shear texture continuous recrystallization took place which led to the formation of a very fine grained microstructure. It is concluded that the very complex strain history in the near-surface layers together with the resulting high work-hardening rate gave rise to the formation of the ultra-fine grains with an average size smaller than 2$\mu\textrm{m}$.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.126-132
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• 2012

This paper deals with a centralized warehouse problem with multi-item and capacity constraint. The objective of this paper is to decide the number and location of centralized warehouses and determineorder quantity (Q), reorder point (r) of each centralized warehouse to minimize holding, setup, penalty, and transportation costs. Each centralized warehouse uses continuous review inventory policy and its budget is limited. A SA (Simulated Annealing) approach is developed and its performance is tested by using some computational experiments.