• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.338-350
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• 2005

Recently, in the field of automobile industry, to solve the problem of reducing the weight of automobile for the improvement of fuel efficiency and the protection of environment, the aluminum alloy parts have been substituted for the steel parts. However, the aluminum alloy does not have as good mechanical property as the steel part. To improve the mechanical property, the semi-solid die casting process is performed to make automobile parts. In the fabrication of semisolid material the control of the liquid segregation is very important to improve the material properties of aluminum alloy. In the present paper we examine the influence of the liquid segregation by the injection conditions in the semi-solid die casting has been investigated.

• Transactions of Materials Processing
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• v.3 no.1
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• pp.3-17
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• 1994

The semi-solid metal forming for vigorously agitated semi-solid alloys has been widely studied over the last decade. Metal forming processes are now being developed using alloys in the semi-solid state, among them are rolling, forging, extrusion, and die casting. Some of these are now employed commercially to produce a components and are also used to fabricate metal matrix composites. The semi-solid materials can be processed either directly during solidification and for this purpose mechanical stirring was demonstrated to produce a highly solidification. This paper is concerned with the influence of processing parameters on limitations of semi-solid forming.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.461-470
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• 2002

The present paper investigates the effect of hot isostatic pressing (HIPing) on mechanical properties, e.g., tensile strength, ductility and impact absorption energy of sand and die casted aluminum alloys. After HIPing at various temperatures and pressure conditions, uniaxial tensile test and Izod impact test of the samples were carried out. The experimental results showed improvements in uniaxial tensile strength, elongation and Izod impact toughness of sand casted aluminum alloy, while deterioration of a tensile strength fur die casted aluminum alloy. The effect of HIPing for microstructure of the cast aluminum alloy was also investigated.

• Journal of Korean Society for Quality Management
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• v.24 no.1
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• pp.96-109
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• 1996

In this paper, we consider the quality problem of black oxide process in casting for which Taguchi method is used. We explain simply the Taguchi method and existing problems in Black Oxide process. We analyze the problem by the quality improvement procedure proposed by Taguchi. The design factors and noises using cause-effect diagram are found, the experiment is made using orthogonal array. After ANOVA, the critical factors are determined and the optimal process condition is designed. After parameter design, we derive the tolerance levels. As a result of changing the levels of process parameters, the variance of quality characteristic was decreased by quarter and the average value was also decreased by half. We estimated the predictable profit of the improvement.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.421-424
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• 2006

In massive hardening concrete structures, early age thermal cracking due to the heat of hydration may occur. There are many massive structures in Incheon bridge project and they have to be carefully treated to prevent thermal cracking. In this paper, an example of analyzed and measured results of hydration heat of pile caps in the Incheon bridge project was represented. Finite element simulations were carried out before casting and curing method was determined using the analyzed result. Sensors were installed before casting and temperature and strain of concrete was measured during curing. Gathered data were compared with the analyzed data and selected control method to prevent cracking was verified. Analyzed result gave good agreement and very few cracking could be found.

• Journal of Industrial Technology
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• v.38 no.1
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• pp.1-7
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• 2018

This paper introduces the design, casting, and sound evaluation results of the Great Bell of 2018 Pyeongchang Winter Olympics. The Olympic Bell was manufactured to announce the opening of the successful Winter Olympics in the world with a grand sound. The bell was designed to the dynamic shape to give a grand and harmonious sound in consideration of the global sports festival. In this study, the performance of the beat making the sound magnificent and the harmony of the bell sound were quantitatively evaluated using acoustical factors. Beat maps were investigated to understand the directivity of the beating sound. The purpose of the research is to present the production technique of a traditional Korean bell that has a dynamic shape and a grand and harmonious sound.

• Composites Research
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• v.17 no.4
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• pp.47-52
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• 2004

This paper established the procedure to fabricate the MWNT/PMMA nanocomposite by using together with injection molding and film casting processes. The fabrication process made it possible for MWNTs to be well dispersed in the PMMA matrix and also it could maintain the well-dispersed state effectively. And the mechanical material properties and SEM images of the fractural surface were observed. Moreover, a surfactant was used to disperse MWNTs more effectively and mechanical material properties were also investigated.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.75-78
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• 2008

Tire molds are manufactured by aluminum casting, direct five-axis machining, and electric discharging machining. Master models made of chemical wood are necessary if aluminum casting is used. They are designed with a three-dimensional computer-aided design system and milled by a five-axis machine. In this paper, a method for generating and machining a tire surface model is proposed and demonstrated. The groove surfaces, which are the main feature of the tire model, are created using a parametric design concept. An automatically programmed tool-like descriptive language is presented to implement the parametric design. Various groove geometries can be created by changing variables. For convenience, groove surfaces and raw cutter location (CL) data are generated in two-dimensional drawing space. The CL data are mapped to the tread surface to obtain five-axis CL data to machine the master model. The proposed method was tested by actual milling using the five-axis control machine. The results demonstrate that the method is useful for manufacturing a tire mold.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.211-214
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• 2007

Solid rocket motor that includes AL powder in propellant gets slag during static firing test. Slag is piled up to weak area in motor case and causes dangerous phenomena like explosion of motor. In this paper, It is shown that boots gap liner casting process was developed and static firing test was performed with better results.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.2 no.2
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• pp.53-62
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• 1979

A widely accepted indicator of a project's economic potential is the internal rate of return (IRR). The primary objective of feasibility analysis for any project is to measure the economic potential for the project, normally defined as the expected return on capital investment. The analysis should be designed to determine whether a project is technically and economically sound, and under what conditions. Therefore, there are factors other than economic potential that must be taken into account in the reasonable composition of an investment program. These kinds of factors can be given proper consideration in project selection after the economic feasibility of alternative projects has been determined. The primary reason for having to choose among different projects is that capital resources are scare : the investment budget is limited. The case project, casting facilities investment project, treated in this paper were selected for their value in illustrating the methods of feasibility analysis. This case project an actual potential project and is analyzed on the basis of the best available data for the specific conditions for that project.