• 한국주조공학회지
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• 제10권4호
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• pp.309-315
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• 1990

Aluminum alloy matrix composites reinforced by SiC particles were prepared by rheocompocasting, a process which consists of the incoporation and distribution of reinforcement by stirring within a semi-solid alloy. When the volume fraction of SiCp and stirring speed were fixed, the dispersion of SiCp in Al-matrix alloy depended on stirring time and solid volume fraction in slurry. The results were as follows : 1) As a dispersed SiCp during stirring at $647^{\circ}C$ in 6063-Al alloy, SiC was better dispersed than that other temperature, where solid volume fraction was 43% in slurry. 2) When increased solid fraction in slurry, rate of dispersing SiC increased during stirring and porosities decreased in matrix alloy after casting. 3) Inspite of stirring with 800rpm, since solid particles of matrix alloy in slurry joined each other and occured joining growth, so that SiC was not dispersed into solid particle.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.174-177
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• 2000

In this paper, The bulging behavior of the solidified shell in continuously cast slabs have been numerically analyzed using three-dimensional elasto-plastic and creep finite element method Three-dimensional model has been applied in order to investigate the effect of the narrow face shell on restraining the bulging deflection. Solidification analysis are carried out by two-dimensional finite difference method. In this way, strains occurring at the solidification front near the narrow face of the slab, as well as those occurring in the board face have been computed. The adequacy of the model has been checked against the experimental results. In addition, the effect of the slab width and casting speed on the bulging are discussed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1065-1072
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• 2010

Case studies published in Korea versus the low ground fault is applied on the bridge based on theory or experience in the design of pile bearing capacity by the value of the expression is designed to conduct field tests Disclosure Load bearing capacity value, the result of applying a reasonable construction cost savings of approximately 10 eokyeowon Has, in the design of site investigation was insufficient to require additional efforts. Apply the appropriate value from the extra support in the design of accurate ground survey and air speed to cut the budget and social technology can ensure the reliability was unknown.

• 대한임베디드공학회논문지
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• 제2권4호
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• pp.221-226
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• 2007

This paper propose a control network system based on IEEE1394 for a multi body robot control. The IEEE1394 has the characteristic of high speed(400Mbps), real-time, stability and plug&play. And IEEE1394 also supports freeform daisy chaining, branching and hot plugging, which reduce cabling complexity and make a system simple. Especially, multi host and broad casting support network data sharing method which is suitable for control network for multi body robot. Through experiment, we show that the proposed control network can interface 48 joints (BLDC motors, gears, and encoders) and four 6-axis force/torque sensors with 4Khz communication bandwidth, which is adequate for a multi body robot.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.3-9
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• 1999

The recent technical trend in hot rolling of steel can be described as process and product technologies which have been progressed with modern mill equipment and computers. Precise gauge and width control can be achieved by up-to-date control methods such as AGC and AWC systems. Roll benders and various shape control systems enabled high quality flatness and crown control. Mills can produce higher tensile materials by new process based on process metallurgy. The use of high speed steel rolls and on line roll grinders make the schedule free rolling easier which results in cost saving. Process itself goes toward continuous and simple flow type which has lower operation. Endless rolling and strip casting are examples of the trend. Materials with higher tensile strength and various functions have been developed in last years to meet the customer's needs and this trend will continue.

• 한국주조공학회지
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• 제14권5호
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• pp.412-418
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• 1994

Efficient algorithm for the solidification simulation by FDM is described from the practical point of views. If a proper time step ${\Delta}t$ is selected, the calculation is accelerated by implicit algorithm with the temperature recovery method of latent heat method. The implicit routine in the calculation is processed by SOR method(relaxation factor＝1.5, truncation error＝$10^{-4}$). The calculation is more accelerated by linear-interpolated explicite algorithm with a time step larger than the minimum value of the time step. This explicit method, which is applicable to the practical casting simulation problems, produces almost same results with about 40% faster calculation speed compared with the conventional explicit method.

• 소성∙가공
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• 제8권5호
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• pp.482-490
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• 1999

7000 series Al alloy with good mechanical properties has been focused with tendency to reduce the components weight of aircraft and automobile. However, it is difficult to manufacture a sound extruded product because of segregation, grain growth, casting defect, surface defect, decreasing extrudability and so on. The objective of this study is to manufacture a new 7000 al alloy more than the extrudability of A7N01 and A7003 through controlling the weight (%) Mg, Zn, Si. Hot extrusion experiments on the axisymmetric rod are performed in 500℃ and also performed analysis of the same process using unmerical analysis method, a coupled rigid-thermoviscoplastic finite element method. Extrusion limit diagram was obtained for the developed alloy by FE-simulation in order to define the relationship of extrusion speed and initial billet temperature.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.808-811
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• 2002

In thixoforming process, the size of Si particles is changed by many parameters of forming. Especially, reheating and heat treatment are very important parameters. It was found that the mechanical properties was significantly improved by the thixoforming process. In this study, to investigate the relation between the mechanical properties and Si particles, the experiment of semi-solid die casting has been performed. Large suspension part with A356 alloy was fabricated with controlled ram speed. The effect of the size and shape of silicon particles on microstructure of tensile test has been investigated.

• 한국정밀공학회지
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• 제15권3호
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• pp.61-67
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• 1998

Rapid prototyping becomes widely used in design and manufacturing of mechanical and aerospace engineering. Here a drag valve disk consisted of complicate configuration has designed by CAD, and prototyped by a stereolithography apparatus (SLA) to confirm the design configuration. Also the prototyped valve disk was used for checking if it could be applied for casting from the view point of accuracy, cost, and time. The rapid-prototyped disk by SLA was compared with a high-speed machined disk by MAKINO V55, and it is found that the prototyping of the disk by SLA appears more economical, more accurate and faster than by machining with MAKINO V55.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.268-277
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• 1999

In order to make an advanced dry-friction engineering material, wax-impregnated nylons were synthesized by anionic polymerization of $\varepsilon$-caprolactam in the presence of apraffin wax. DNX-125S, which has lowest melting point among four different kinds of waxs investigated, showed excellent miscibiility with $\varepsilon$-carprolactam and no effect on the polymerization reaction. Five different kinds of wax-impregnated nylons from of DNW-125S content 0% to 8% were synthesized and tested. Among the samples, wax-free nylon has the highest yield and tensile strength and hardness, while the specimen with2% wax has the largest elongationi and energy absorption to break. The wax-impregnated nylon with a wax content 6% showdd the smallest friction coefficient under slow sliding speed and low load. Bus as the sliding speeds were increased to high, thespcieimen with 8% wax has better friction property.