• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1804-1809
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• 2003

In a large-scale chemical plant, there are scheduling problems in inventory and packing process although production process is stabilized. The profit of the plant is restricted by these problems. In order to improve these problems, integrated scheduling model, which is concerned with whole processes from production to shipment, has been developed in this paper. In this model, decision variables are production sequence, silo allocation, amounts of bulk shipment and packing amounts. In case of a real plant, it is hard to solve by deterministic methods because there are too many decision variables to solve. In this paper, genetic algorithm is presented to solve a PVC process scheduling model within an hour with PCs.

• Steel and Composite Structures
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• v.24 no.2
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• pp.239-248
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• 2017

Friction dampers are displacement dependent energy dissipation devices which dissipate earthquake energy through friction mechanism and widely used in improving the seismic behavior of new structures and rehabilitation of existing structures. In this paper, the cyclic behavior of a friction damper with different friction materials is investigated through experimental tests under cyclic loading. The damper is made of steel plates, friction pads, preloaded bolts and hard washers. The paper aims at investigating the hysteretic behavior of three friction materials under cyclic loading to be utilized in friction damper. The tested friction materials are: powder lining, super lining and metal lining. The experimental results are studied according to FEMA-356 acceptance criteria and the most appropriate friction material is selected by comparing all friction materials results.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.106-113
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• 2000

One of the recent changes in machining technology is rapid application of micro- and high precision grinding processes. A fine groove generation is necessary for the fabrication of optics, electronics and semiconductor parts. Slot grinding is very efficient for the generation of micro ordered groove with hard and brittle materials. In the process of slot grinding, chipping at the sharp edges and microcracks of the ground grooves are inevitable defects. Chipping should be reduced for the improvement of surface integrity. Mechanical contact with diamond grits causes microcracks at the grooves. This damage resides subsurface, and can be the cause of failure of the punch die. This paper deals with chipping generation at the sharp edges, surface integrity of side groove and fracture strength is related to the microcracks in the slot grinding.

• Proceedings of the KWS Conference
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• 1999.10a
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• pp.297-298
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• 1999

Cemented carbides material (WC-Co hard alloy) were recognized very important and expensive tool or die assembly parts because of compose for the main elements of rare metal (W and Co etc). This research was developed to separate and recover of WC fine powder contained by WC-Co materials. Recycling process was a new method named by the Tin impregnation for decobaltification on cemented carbides. This reaction occurred to product a brittle Co-Sn intermetallic compounds, thereafter it carried out by acid cleaning solution and physical milling or powdering. New process was able to recover about 60％ WC fine powder from 1 to 5 ${\mu}{\textrm}{m}$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.25-32
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• 2010

Compared to general lighting method, the lighting system that uses optic fiber can provide only the visible light of good quality to subject by eliminating ultraviolet ray and infrared ray. Thanks to this merit, it is possible to prevent the hard phenomenon of subject caused by ultraviolet ray and infrared ray and to provide the agreeable light environment. This study developed indoors illumination system of high color rendering on the basis of plastic optic fiber with excellent optical property and processing to substitute halogen lamp which has been used for excellent color rendering in spite of low efficiency and short life. Producing pilot product of the designed illumination system and evaluating the property of electric and optical property, ultraviolet ray radiation quantity and temperature property, this study verified the excellence of suggested lighting system of plastic optic fiber.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.3
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• pp.62-69
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• 1995

In order to investigate the effect of TiN coating on corrosion fatigue behavior of metal, the rotary bending corrosion fatigue tests were carried out in 3% NaCl solution by using the round bar specimens of high-speed steel, SKH-9, coated with TiN by PVD method. From the experimental results, fatigue strength of TiN coating steel in air was obvious improvement as compared with that of the substrate because of the restriction of dislocation movement in near surface of the substrate by hard thin film. In 3% NaCl solution, corrosion fatigue life of TiN coating specimen in high stress level was improvement same as in air. But in low stress level, corrosion fatigue life of TiN coating one was equivalent to that without coating, due to much crack initiated from corrosion pits formed at the substrate by failure of coating layer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1154-1158
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• 1995

Electrical Discharge Machining, with its ability to machine hard metals and tough shapes has become a very desirable process. In the past few years, Electrical Discharge Machining (EDM) has been solidly established in tool-room and large-scale production. However, in spite of its indispensability in many areas of metal removal applications, the theoretical basis of EDM process is yet to be established. More importantly, the information regarding essential technology parameters such as machining rate and resulting surface roughness integrity, has not been raised to the level of a general technical science. The paper presents a method, which can be determining approprate machining parameters for the given parameters such as electrode wear and surface roughness based on machining guideline utilizing neural networks.

• Journal of Powder Materials
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• v.5 no.4
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• pp.293-298
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• 1998

In all larger hardmetal workshops furnaces for dewaxing, vacuum sintering or vacuum and overpressure sintering are today's standard. The furnace technology is well established. Equipment specifications such as operating overpressure, determine sintering cost, product quality, safety and reliability of the furnace and ultimately influence the competitiveness of the hard metal procucer in the global market. Essential furnace requirements are an efficient utilization of the furnace, an environmental friendly dewaxing system, high temperature uniformity, metallurgical treatment with process gases, as well as reduced cooling time by means of rapid cooling. Examples of reduced sintering costs are described achieved using a new design of vacuum sintering furnace with an improved rapid cooling device, cooling times are reduced by up to 45%. Additionally, a cost comparison of two different designs of vacuum overpressure sintering furnaces are included.

• Journal of Powder Materials
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• v.3 no.4
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• pp.266-270
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• 1996

The microstructure evolution during sintering of a compact being composed of three layers of (WC-15%Co)/Fe powder mixture with different Fe contents has been observed. The Fe contents in the respective (WC-15%Co)/Fe layers were varied by 20%. 50%, and 90% in sequence by volume from a top layer to a bot- tom layer. The sintering temperatures and times were varied from 110$0^{\circ}C$ to 125$0^{\circ}C$ and from 1 h to 4 h, The compact layer was not densified below 120$0^{\circ}C$ in 4 h. Appropriate sintering temperature and time conditions for making a multi-layered hard metal compact were determined as 125$0^{\circ}C$ and 3 h, respectively.

• Journal of the Korean Ceramic Society
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• v.31 no.11
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• pp.1355-1361
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• 1994

With the availability of ceramics (Al2O3, Al2O3-TiC), it is possible to machine very hard steel at different cutting conditions. When hardened steel STD 11 is turned using ceramic tools, chip formation is observed conical-herical and arc chips with a cyclic saw toothed type. The main cause of saw toothed chip formation is observed conical-herical and arc chips with a cyclic saw toothed type. The main cause of saw toothed chip formation is found to be periodic gross shear fracture extending from the free surface of the chip toward the tool tip. In regard to chip control, ceramic Al2O3 is superior to the other cutting tools. The roughness of machined surface was getting worse with increasing of cutting speed and feed.