• Special Issue of the Society of Naval Architects of Korea
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• 2006.09a
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• pp.77-80
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• 2006

In recent booming up of the ship building market, the supplying of large scale casting is difficult to keep the delivery schedule for ship yard because of the restrict manufacturer in Korea. And also, it is main cause to rise-up the cost of castings. This paper describes the outline of guidance of optimizing design for Rudder Horn Casting to reduce the risk of the delivery problem to ship yard.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.138-141
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• 1997

CFM(Cast Forge Method) is widely used in manufacturing industry to produce aluminium parts with good mechanical properties and low production cost. CFM is the process which produces a final products by forging from the initial billet by casting. The study on this paper covers the automatic design method which finds a pertinent shape for initial billet using Fast Fourier Transform, low-pass frequency filtering and FEM simulation of the nonisothermal forging process by DEFORM. These works will give us an information to enhance the low strength of a aluminium casting.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03a
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• pp.165-171
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• 1996

Recently, to improve the productivity in the continuous casting process, thin slab continuous caster which is one of the new steelmaking technologies by a high speed casting has been introduced. In the process of the thin slab continuous cast, there is more possibility than convnetional one that the deformation be occurred by the bulging of solidified shell, since the thickness of soliidfied shell is very thin as much as 60mm after the casting is finished. In some cases of severe bulging, there might be more breakout. In this paper, using finite difference method , solification analysis of slab is made as well as the thicknessof solidified shell and temperature are calculated. Also, based on the data of the calculated temperature, the deformed behavior of solidified narrow face is anlayzed with the MARC which is a package program for finite element analysis.

• Transactions of Materials Processing
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• v.14 no.1 s.73
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• pp.49-56
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• 2005

In the semi-solid die casting process, an important thing is the flow behavior of semi-solid materials. The flow patterns of the semi-solid material can make the defects during die filling. To control the flow patterns is very important and difficult. In this paper, the flow behavior of the semi-solid A356 alloy material during die filing at various die gate shapes has been observed with the grain size controlled material. The effect of the gate shape on the die filling characteristics was investigated. The filling tests in each plunger stroke were experimented, and also simulated on the semi-solid material die casting process by MAGMAsoft. According to the filling tests and computer simulation, the effect of the gate shape on liquid segregation has been investigated.

• The Journal of Korea Robotics Society
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• v.5 no.4
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• pp.302-308
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• 2010

A gradient method can provide a global optimal path in indoor environments. However, the optimal path can be often generated in narrow areas despite a sufficient wide area which lead to safe navigation. This paper presents a novel approach to path planning for safe navigation of a mobile robot. The proposed algorithm extracts empty regions using a ray-casting method and then generates temporary waypoints in wider regions in order to reach the goal fast and safely. The experimental results show that the proposed method can generate paths in the wide regions in most cases and the robot can reach the goal safely at high speeds.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1364-1367
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• 1996

Recently, direct rolling process, called as strip casting process, has been interested in to save production cost by reducing forming processes. In direct rolling process, since a steel strip of thickness 1-5(mm) can be produced directly from molten metal, it can eliminate secondary hot rolling process. On the other hand, since many process variables are existed in this process and relation of these variables is very complex, it is difficult to realize the process design and the quality control. In this paper, as first step to overcome above difficulties, the quantitative relationship of the process variables affected to quality of the strip has been carried out through the numerical analysis. Also, we determined the process variable to monitor the quality in the direct rolling process. As a result, we show that the solidification final point, called as Nip point, was related directly to quality of the strip.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.842-845
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• 2000

The purpose of this paper is to investigate the influences on mechanical properties of motor pistons manufactured by casting, conventional forging and powder forging, using the comparison of characteristics like microstructure, hardness, tensile strength, and elongation. To form conventional forging piston, the experiment of visioplasticity was performed. As the model material, plasticine was used. To form powder forging piston, the shape of piston was simplified as simple cup shape. Material properties like workability, density variation before and after forging, and strain loci of material during forging were investigated. Powder forging and conventional forging technologies were effective to gain dense microstructure. In powder forging, distribution of such dense microstructuer was uniform. For hardness, pistons from powder forging and conventional forging technologies were much better than that from casting. For tensile strength and elongation, powder forging and conventional forging technologies were also advantageous.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.405-408
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• 2003

Generally, the life of casting mold is limited by fatigue fracture or dimensional inaccuracy originated from wear in high temperature. Although recent research of metallic materials in high temperature fatigue have been much accomplished, many studies on brittle material as a die steel in high temperature fatigue does not have been reported. Especially, the study on the fatigue behavior over the transformation temperature is not studied sufficiently because of its difficult analysis and experiment. Therefore, reliable results of brittle material in high temperature fatigue behavior are needed. In this paper, stress-strain curves and stress-life curves in die STD61 steel are carefully examined between room temperature and 90$0^{\circ}C$, as the basic experimental data are used to predict from fatigue life of casting mold.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.28-34
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• 2008

Mg alloy is widely used for the IT, auto and consumer electronics industries. Semi-solid casting(SSC) of magnesium alloys is used to produce high quality components. SSC process is analogous with the injection molding of plastics. The high strength and low weight characteristics of magnesium alloys render the high-precision fabrication of thin-walled components with large surface areas. To produce thin-walled magnesium alloy parts, SSC process parameters on the quality of the finished product should be clearly studied. In this paper, to select optimal process parameters, Taguchi method is applied to the optimal design of the process parameters in the SSC process. The die temperature, injection velocity and barrel temperature of the SSC process are selected for the process parameters. The effectiveness of the optimal design is verified through the CAE software.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.4
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• pp.485-495
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• 2001

This paper presents a similarity solution for the directional casting of binary peritectic alloys in the presence of shrinkage-induced flow. The present model retains essential ingredients of alloy solidification, such as temperature-solute coupling, macrosegregation, solid-liquid property differences, and finite back diffusion in the primary phase. An algorithm for simultaneously determining the peritectic and liquidus positions is newly developed, which proves to be more efficient and stable than the existing scheme. Sample calculations are performed for both hypo- and hyper-peritectic compositions. The results show that the present analysis is capable of properly resolving the solidification characteristics of peritectic alloys so that it can be used for validating numerical models as a test solution.