• Journal of Korea Foundry Society
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• v.3 no.1
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• pp.13-21
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• 1983

In order to determine the feeding distance of aluminiun alloys (Alsi7Mg and AlCu4Ti) bar castings in the sand mold, the distance of the sound castings has been observed by radiograph for various risers, melt treatment, and casting design. Variation of porosity and hardness with the distance from the riser were also measured in order to determine the casting soundness. The results obained were as follows; 1) The modulus of riser should be 1.4 times of the casting`s 2) The maximum distance which can be made sound is greatly dependent on chemical composition and ingate location, and follows the rules given by the formula; a) When the melt flows into the casting first, and the riser afterward, D = 37.7 ${\sqrt{T}}$ for AlSi7Mg D = 31.2 ${\sqrt{T}}$ for pure aluminium D ${\ge}$ 54.8 ${\sqrt{T}}$ for AlCu4Ti Where T = casting thickness in mm Of this maximum distance, $aa{\sqrt{T}}$ for AlSi7Mg and 7.5 ${\sqrt{T}}$ for pure aluminium is made sound by the chilling effect of the casting edge. b) When the melt flows into the casting passing through the riser, $30{\times}30{\times}600mm$ bars can be made sound in all cases 3) Percentage of porosity is higer in AlCu4Ti than AlSi7Mg. And it is increased gradually by moving closer to the riser in case of $30{\times}30{\times}600mm$ bars, but for the $30{\times}30{\times}600mm$ bars it is increased gradually by moving closer to the center of bars. 4) Hardness variation is similar to the tendency of porosity. And it decreased gradually with approaching to the center in case of $30{\times}30{\times}600mm$ bars.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.225-225
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• 2011

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.06a
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• pp.11-11
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• 2006

• Journal of Korea Foundry Society
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• v.38 no.1
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• pp.1-8
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• 2018

In this study, we focused on the correlation between the solidification structure, heat treatment and mechanical properties of the A356 alloy according to the conditions of Sr modification. The microstructural evolution of the eutectic Si and ${\alpha}-Al$ phase in the A356 alloy castings depending on the amount of Sr were investigated during solid solution heat treatment using an optical microscope, a scanning electron microscope and an image analyzer. In addition, tensile tests on the heat treated materials examined the relationship between the microstructure and the fracture surface. The as-cast A356 alloys under 40 ppm Sr showed an undermodified microstructure, but that of the added 60-80 ppm Sr had well modified structure of fine fibrous silicon. After solid solution treatment, the microstructure of the undermodified A356 alloy exhibited a partially spheroidized morphology, but the remainder showed the fragmentation of fibrous shaped silicon. The spheroidization of the eutectic silicon in the modified A356 alloys was completed during heat treatment, which was very effective in increasing the elongation. This is supported by the fracture surface in the tensile test.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.623-628
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• 2001

The objective of this study is to find out the effect of Horizontal vibration on the compressive strength for 7 days and 28 days cured concrete specimens according to the kind of fine aggregates and the variation of vibration velocities, and times began to vibrate. Three kinds of fine aggregate(river sand, sea sand, crush sand), three types of vibration velocities(0.25, 0.5 0.1kine(cm/sec)), and four steps of times(0, 3, 6, 9 hours after concrete casting) were chosen as the experimental parameters in this study, the vibrations are applied for 30 minutes in each case. From this study, the variation with type of fine aggregate doesn't show tendency and the compressive strength decreases with increasing vibration velocity. When the vibration force time is more than 6 hour, It shows that compressive strength decreases under the condition of vibration velocity which the value is 0.5 kine and 1 kine, respectively.

• Journal of Korea Foundry Society
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• v.7 no.1
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• pp.45-52
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• 1987

The effects of melting and casting conditions on cast structures of Cu-Sn-Pb alloys were studied. Specimens were prepared at different pouring temperatures of $1100^{\circ}C$ to $1260^{\circ}C$ with use of various kind of molds, green sand mold, $CO_2$ sand mold, shell mold, furan sand mold and metallic mold. (1) The transition of equiaxed to columnar structure greatly influenced by adding elements and mold binders. (2) The change of equiaxed structure according to pouring temperatures were expressed by separation theory. Lower pouring temperature and rapid cooling rate increase hardness and it's further increase was shown in the region of columnar structure. (3) Proper controls of pouring temperature, cooling rate and mold binder were important factors to improve wear properties of Cu-Sn-Pb alloys castings.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.124-131
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• 2000

Rapid Prototyping(RP) models are no longer used only for design verification. Currently, parts built utilizing layer manufacturing technology can be employed as functional prototypes and as patterns or tools for different manufacturing processes such as vacuum casting, investment casting, injection molding, precise casting and sand casting. This trend of Rapid Prototyping application meets the requirement of concurrent engineering and its range covers a more spreaded area. The aim of this paper is saving the manufacturing lead time and cost of plastic parts having hollow space shapes used by prototype-car. Using rapid prototype patterns, made by the Selective Laser Sintering(SLS) technique, a new approach of manufacturing resin-based blow mold is discussed. It has a great potential fur making prototype-car parts with the batch size of under 200 parts, in case of rapid modification due to a subsequent design changes in developing stage. So, the process proposed in this research shows reduction of process time and manufacturing cost when compared with the conventional process such as a Zinc Alloy fur Stamping(ZAS) mold.

• Journal of Korea Foundry Society
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• v.43 no.4
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• pp.194-200
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• 2023

The heat transfer of the mold in the casting process has been calculated by considering the mold as a uniform isotropic material. Since the mold was not a uniform isotropic material, however, the calculation was performed with approximate values, and in particular, estimated values were used when considering compaction and the amount of added binder. In this study, a calculation algorithm of the thermal properties of the sand mold was developed. An algorithm for calculating the thermal conductivity and specific heat based on a thermal resistance model in the case of mono-dispersed sand grains was also developed and applied to sand molds with various size distributions. The thermal properties of sand were calculated for artificial sand, and relatively close values compared to the experimental values were obtained.

• Archives of design research
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• v.16 no.2
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• pp.291-300
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• 2003

In metalcraft, there are two kind of skills, one is forming and the other is decoration. And we could discern these skills as metal casting and metal hammering.. In metal casting, there are sand mould, cire perdus, stone mould and sealed monld; In metal hammering, metal forging, repousse technique and metal sheet making. After make form, craftman can use the decoration skills. There are chasing hammering, line carving, dotted line engraving, hair line engraving, kicking line engraving, ring punched ground, inlay, filigee and granulation skills. In korean traditional copper alloy, the craftman used forming and decoration skills. In Korea, tradionally the clatter use bronze for copper alloy; in case of Japan, they use violet coloring, and in case of Chinese, they like to use bronze used copper alloy. In case of Alloy, korean craftman used bronze traditionally, but recently the copper alloy skill is usually used; in case of Japan shibuichi and shakudo skills are used; and in Chinese copper, brass and cupronikel alloy are used.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.83-89
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• 2019

In the conventional casting and forging method, there is a disadvantage that a mold is an essential addition, and a production cost is increased when a small quantity is produced. In order to overcome this disadvantage, a metal 3D printing production method capable of directly forming a shape without a mold frame is mainly used. In particular, overseas research has been conducted on various materials, one of which is a metal printer. Similarly, domestic companies are also concentrating on the metal printer market. However, In this case of the conventional metal 3D printing method, it is difficult to meet the needs of the industry because of the high cost of materials, equipment and maintenance for product strength and production. To compensate for these weaknesses, printers have been developed that can be manufactured using sand mold, but they are not accessible to the printer company and are expensive to machine. Therefore, it is necessary to supply three-dimensional casting printers capable of metal molding by producing molds instead of conventional metal 3D printing methods. In this study, we intend to reduce the unit price by replacing the printing method used in the sand casting printer with the FDM method. In addition, Ag paste is used to design the output conditions and enable ceramic printing.