• Journal of Conservation Science
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• v.28 no.4
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• pp.417-425
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• 2012

Bronze Mirror with fine linear designs in the bronze age shows the greatest alloy and casting skills of the day and presents the highest level of handcrafting and molding techniques. Lately, Lost-wax casting and sand-mould casting were used for the restoration of the national treasures of No. 141 and No. 143 Bronze Mirror with fine linear designs. Also the Principle Component Analysis, Microstructure Analysis, X-ray and SEM-EDS analysis were carried out on the restored Bronze Mirror with fine linear designs. Bronze Mirror that is made of sand-mould casting, hardly has a eutectoid and it is observed as a ${\alpha}$ dendrite. In contrast, Bronze Mirror that is made of lost-wax casting, the eutectoid has found through the ${\alpha}$ dendrite. As we compare lost-wax casting to the sand-mould casting through an analysis of restored Bronze Mirror, mostly, sand-mould casting has better castability and it seems that it brings a clear and equal Bronze Mirror as it has a low cooling rate. In this way, we are able to confirm that there is a big difference between the method by lost-wax casting and by sand-mould casting through an analysis of microstructure and restored Bronze Mirror. If such research will be continued, it will be an opportunity that investigates diverse methods of production techniques.

• Journal of Korea Foundry Society
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• v.15 no.3
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• pp.291-297
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• 1995

The mechanical properties and fracture toughness of permanent mold cast austempered gray cast iron(AGI) were compared to those of sand cast AGI. The iron was melted to eutectic composition in order to get better castability especially in permanent mold casting. Specimens prepared for tensile, impact and fracture toughness test were austenitized at $900^{\circ}C$ and austempered at $270^{\circ}C$ and $370^{\circ}C$ for 1 hour. The strength, impact and fracture toughness of permanent mold cast AGI were found to be superior to those of sand cast AGI. The maximum value of 836 MPA in tensile strength, was obtained at the austempering temperature of $270^{\circ}C$. But ductility of AGI was not improved by permanent mold casting.

• 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 Safety
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• v.11 no.1
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• pp.3-10
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• 1996

The mechanical properties and fatigue crack growth rate fracture toughness of permanent mould cast austempered gray cast iron(AGI) were compared to those of sand cast AGI. Specimens prepared for tensile, impact and fatigue test were austenitized at $900^{\circ}C$ and austempered at $270^{\circ}C$, $320^{\circ}C$, $370^{\circ}C$ and $420^{\circ}C$ for 1 hour. The strength, impact and fatigue crack propagation behavior of permanent mold cast AGI were found to be superior to those of sand cast AGI. Maximum values in tensile strength, BHN, Charpy impact energy, were obtained at the austempering temperature of $270^{\circ}C$. Samely, the slowest fatigue crack growth rate was appeared at the austempering temperature of $270^{\circ}C$. But ductility of AGI was not improved by permanent mould casting.

• Journal of Korea Foundry Society
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• v.10 no.1
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• pp.31-42
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• 1990

The full mould casting process in one of the newly developed techniques which has many advantages. Unbonded sand mould has been prepared for the major mould and $CO^2$ gas mould has been used occasionally for comparison. Patterns were built up with expanded polystyrene and coated with three different materials. Silica, graphite and zircon were used for the coating layer. The effects on fluidity and temperature loss of molten metals were investigated. The molten metals were Al-5% Si alloy, Cu-30% Zn alloy and gray iron of approximately 4.0% of carbon equivalent. Experimental variables were runner section area, superheat, sprue height, coating materials, coating thickness and apparent density of EPS pattern. The effects of coating materials on fluidity and temperature loss of the molten metals during transient pouring are summarized as follows : As runner section area, superheat and sprue height increased, fluidity increased. Temperature loss decreased as runner section area and sprue height increased. However, reversed effects were observed in the case of superheat increment. The coating materials decreased the fluidity of each alloy in the order of silica, graphite and zircon. Zircon brought to the highest temperature loss among the coating materials used. The fluidity increased in the order gray iron, Cu-30% Zn and Al-5% Si alloy while temperature loss in the reverse order. Especially in case of reduced pressure process, the fluidity was increased apparently. Al-5% Si alloy showed the lowest temperature loss among the alloys. The increment of the apparent density of EPS pattern resulted in the fluidity decrease and temperature loss increase. The relation between fluidity and temperature loss of each alloy can be expressed by the following equation within the coating thickness limit of 0.5-1.5㎜. F^*={\frac{a}{T^*-b}}-c$ where, $F^*$ : fluidity in the Full mould, $T^*$ : temperature loss in the mould. a : parameter for full mould. b, c : constants.

• Korean Journal of Metals and Materials
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• v.46 no.5
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• pp.304-309
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• 2008

Magnesium alloys containing $Mg_2Si$ particles, as a promising cheap heat-resistant magnesium alloy for automobile power train parts applications, are attracting more attention of both material scientists and design engineers. Modification of the Chinese script shape $Mg_2Si$ particle is a key for using this alloy in sand or permanent mould casting. In the present work, the modification effect of Sr and Sb on the corrosion properties of the Mg-5Al-2Si alloy was investigated. Sr or Sb addition promoted the formation of fine polygonal shape $Mg_2Si$ particles by providing the nucleation sites. Sr was more effective element than Sb for shape modification of Chinese script shape $Mg_2Si$. Such improved microstructure of the modified alloy resulted in large improvement in corrosion resistance as compared to unmodified Mg-5Al-2Si alloy.

• Design & Manufacturing
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• v.7 no.1
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• pp.45-49
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• 2013

Since the shell-molds are used to make casting the metal parts for the automobile industry, the quality may well be inconsistent with the lower productivity, increasing the cost of the end products. The primary elbow design shell molded steel castings being produced through extrusion process has $180^{\varnothing}$ O.D., $150^{\varnothing}$ I.D., 14mm thickness and 400mm length, while being processed onto the left side of the tubing. The primary cause for the poor processing is the uneven manual shell molding. If the manual shell molds should be produced to have even quality, they would not be processed for tube linking. The purpose of this study was to develop the flask-molds for manufacturing of the shell molds to ensure mass-production, consistent quality, ommission of processing and comfortable working environment. For this purpose, four flask-molds were produced and thereby, four shell molds were assembled. In particular, the shell molds for processing were formed of the fine coated sand to be blown. As a result, productivity increased about three times, while a consistent quality was ensured. Furthermore, the tubes could be linked with each other without being processed, while pallets could be stacked, stored, transported and managed more easily. In a nut-shell, the molding theory could be applied more effectively. However, it is conceived that this study should be followed up by future studies which will research into reliability and endurability of the end products.