• Korean Journal of Heritage: History & Science
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• v.53 no.1
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• pp.168-183
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• 2020

Efforts had been made to eliminate the brittleness unique to cast ironware from 5 BC up until the time that cast ironware became widely used. One of the techniques used to this end was to produce the cast ironware in one kiln and then anneal it in another kiln. This technique condensed or removed the carbon in the structure to eliminate the brittleness of cast ironware and enable forging. To clarify the nature of this technique, this study examined cast ironware made of malleable cast iron, which manifests the characteristics of the annealing technique for cast ironware excavated on the Korean peninsula, based on current steelmaking technology and research results from China and Japan. Results confirmed that all cast ironware made of malleable cast iron had been imported into Korea until the Proto-Three Kingdoms Period. Also, since the Chiljido (Seven-Branched Sword), which is housed at the Ishigami Shrine in Japan, appears to have been produced in the Korean peninsula, it is determined that Baekje in the 4^th century must have possessed such an annealing technique. At that time, however, iron was produced mainly with an iron bloom, and a large amount of forged iron was produced with a steel bloom smelted from an iron bloom. In addition, most of the cast ironware that was used previously, except for cast iron hoes, had been replaced by forged ironware. In other words, this annealing technique was not used frequently until the Three Kingdoms Period. However, it spread broadly during the Unified Silla Period in so much as it was identified in the Jangan-ri remains, which represented the regional hub of iron production and distribution.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.777-785
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• 2000

The low-cycle fatigue behaviors of cast AI-Si alloy and composite with reinforcement of SIC particles were compared with those of extruded unreinforced matrix alloy and composite in order to investigate the influence of cast and extrusion processes on the cyclic deformation and fatigue life. Generally, both cast and extruded composites including the unreinforced alloy exhibited cyclic hardening behaviour, with more pronounced strain-hardening for the composites with a higher volume fraction of the SiC particles. However, cast composite under a low applied cyclic strain showing no observable plastic strain exhibited cyclic softening behavior due to the cast porosities. The elastic modulus and yield strength of the cast composite were found to be quite comparable to those of the extruded composite, however, the extrusion process considerably improved the ductility and fracture strength of the composite by effectively eliminating the cast porosities. Low-cycle fatigue lives of the cast alloy and composite were shorter than those of the extruded counterparts. Large difference in life between cast and extruded composites was attributed to the higher influence of the cast porosities on the fatigue life of the composite than that of the unreinforced alloy material. A fatigue damage parameter using strain energy density effectively represented the inferior life in the low-cycle regime and superior life in the high-cycle regime for the composite, compared to the unreinforced alloy.

• Journal of environmental and Sanitary engineering
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• v.14 no.1
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• pp.97-102
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• 1999

This study was carried out view that reuse of sludge of adsorbent for benzene in carbonized cast compare with activated carbon. Not only the carbonized cast is good than carbonized carbon in cation exchange capacity and 12 adsorption capacity, but also benzene adsorption capacity is no differences compare to activated carbon. As results, benzene adsorption capacity of carbonized cast and activated carbon are decreased as temperature increase($25~70^{\circ}C$).It is compatible in Lamgmuir model. Therefore, carbonized cast is applied general adsorbent. From experimental results and data regression, in model concerning effect of temperature, relative errors between the experimental data and those calculated by the model are within the range of 1.2~7.8%. In relative humidity effect (RH 0.25~0.50) of benzene adsorption, modified Freundlich model : $QB_{enzene}{;\}QB_{enzene},{\}_{RH=0}=1-kRH^{IN}$, relative errors between the experimental data and those calculated by the model are within are range of 0.5-5.1%. The constants k and l/n in equation were found to be 1.25, 1.89 in carbonized cast.

• Journal of Korea Foundry Society
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• v.5 no.3
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• pp.5-12
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• 1985

Many researchers have studied the eutectic solidification of CV Graphite Cast Iron qualitatively. However quantative studies have not been done. The type of eutectic solidification of CV Graphite Cast Iron treated with CG Alloy (Fe-Si-Mg-5Ti-Ca-Ce) was studied quantitatively through M.D.E. value (Mushy Degree of Eutectic Solidification) = $t_2/t_1)$, where $t_1$ is the difference of the eutectic solidification starting time between surface and center part of the casting sample, and $t_2$ is the time of eutectic solidification of the center part. Following results were obtained. (1) The M.D.E. value of CV graphite cast iron lies between that of spheroidal graphite and that of flake graphite cast iron but is closer to that of Flake graphite cast iron. (2) The M.D.E. value of CV graphite cast iron depends upon CV ratio. (3) The time required for eutectic solidification increases as graphite form is changed from Flake, CV. to spheroidal graphite. (4) The M.D.E. value increases as cooling rate increases.

• Journal of Korea Foundry Society
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• v.1 no.2
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• pp.2-9
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• 1981

Graphite spheroidization and scaling resistance of cast iron containing 5-10% Al were investigated. It is impossible to obtain spheroidal graphite in cast iron containing Al with 8 % and over, but possible to obtain spheroidal graphite even in cast iron with an Al content of about 10 % by increasing Si content. In the scaling test carried out under the heating condition of $950^{\circ}C$ in air for total of 50 hours, the scaling resistance of cast iron containing Al with 8 % and over was remarkably superior, and also spheroidal graphite cast iron was superior to flake graphite cast iron. The scale became thinner more compacts and more protective with increasing Al content.

• Bulletin of the Korean Space Science Society
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• 2005.10a
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• pp.59-59
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• 2005

• Korean Journal of Heritage: History & Science
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• v.53 no.2
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• pp.4-23
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• 2020

The purpose of this study was to explore the diversity of Korea's iron casting technology and to examine various casting methods. The study involved a literature review, analysis of artifacts, local investigation of production tools and technology, and scientific analysis of casting and cast materials. Bellows technology, or Bulmi technology, is a form of iron casting technology that uses bellows to melt cast iron before the molten iron is poured into a clay cast. This technology, handed down only in Jeju Island, relies on use of a clay cast instead of the sand cast that is more common in mainland Korea. Casting methods for cast iron pots can be broadly divided into two: sand mold casting and porcelain casting. The former uses a sand cast made from mixing seokbire (clay mixed with soft stones), sand and clay, while the latter uses a clay cast, formed by mixing clay with rice straw and reed. The five steps in the sand mold casting method for iron pot are cast making, filling, melting iron into molten iron, pouring the molten iron into the cast mold, and refining the final product. The six steps in the porcelain clay casting method are cast making, cast firing, spreading jilmeok, melting iron into molten iron, pouring the molten iron, and refining the final product. The two casting methods differ in terms of materials, cast firing, and spreading of jilmeok. This study provided insight into Korea's unique iron casting technology by examining the scientific principles behind the materials and tools used in each stage of iron pot casting: collecting and kneading mud, producing a cast, biscuit firing, hwajeokmosal (building sand on the heated cast) and spreading jilmeok, drying and biyaljil (spreading jilmeok evenly on the cast), hapjang (combining two half-sized casts to make one complete cast), producing a smelting furnace, roasting twice, smelting, pouring molten iron into a cast, and refining the final product. Scientific analysis of the final product and materials involved in porcelain clay casting showed that the main components were mud and sand (SiO₂, Al₂O₃, and Fe₂O₃). The release agent was found to be graphite, containing SiO₂, Al₂O₃, Fe₂O₃, and K₂O. The completed cast iron pot had the structure of white cast iron, comprised of cementite (Fe₃C) and pearlite (a layered structure of ferrite and cementite).

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.6
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• pp.858-866
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• 1998

Soldering is the usual method used to correct an unstable fixed partial denture framework at patient's try-in; However, presoldering base metal alloys is technique-sensitve and results are unstable because it is difficult to maintain uniform heat distribution and to prevent oxidation of an alloy. A cast-joining technique has been developed by Weiss and Munyon for repair, correction and addition to base metal framework. This joining technique eliminates the problem with presoldering of non-precious frameworks. The object of this study was to 1) compare the relative flexure strength and the joining effectiveness of Ni-Cr-Be cast in two pieces and 'pre-soldered' versus in two pieces and 'cast-joined'. 2) determine the effect of increasing the number of retentive grooves on the face of the cast and 3) determine the effect of the relative matched position of groove patterns on flexure strength. The joining effectiveness can be expressed by the ratio of the mean flexure stress of soldered or cast-joined specimens to that of one-piece cast. Resin rods 3mm in diameter were used as pattern of specimens for one-piece casted, presoldered, and cast-joined groups. Cast-joined specimens had two different patterns of retentive grooves on the joined faces. Type A had cross-shaped grooves 1mm in depth. 0.6mm in width. Type B was the same except for the addition of one more retentive groove. In the experiment connecting cast-joined specimens, half of specimens with type A pattern had their patterns on the faces of paired casts matched with each other as mirror image. With the rest pairs, it was proceeded that one of paired casts turned 45 degrees so that the patterns crossed. Half of specimens with type B pattern also had the patterns matched as mirror image; However, here, one of paired casts turned 90 degrees with the other pairs. Retentive groove in this study lacked the intentional undercuts, in contrast with the suggestion of Weiss and Munyon. The specimens were subjected to four-point flexural loading in an Instron testing machine. The midspan flexural stress was calculated at the point of initial plastic strain as determined from a strip-chart recorder or at the point of failure if this occured at a lower stress level. Within the scope of this study, the following results were obtained. 1. The presoldered group showed flexural strength at least 2 times higher than the cast-joined groups. Its joining effectiveness was 82%. 2. In cast-joined groups, the flexural strength of joints with type B patterns exhibited 1.5 times that of joints with type A patterns. Joining effectivenesses were 38% for type B patterns, 25-26% for type A patterns. 3. The relative matched position of groove patterns did not have any significant effect on flexural strength of the cast-joined specimens with either type A patterns or type B patterns(p>.05).

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.4
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• pp.461-467
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• 1993

The purpose of this study was to evaluate the effects of method for construction of cast post and type of dental cement on the retention of cast post. The wax patterns or Duralay resin patterns were used for construction of cast post. The dental cements used in this study were zinc phosphate cement(Fleck's zinc cement, Mizzy INc., U.S.A.), glass ionomer cement(Fuji I, G-C Co., Japan), and resin cement(Panavia-EX, Kuraray Co., Japan) and the retention of cast post was measured with Instron Universal Test Machine(Instron Engineering Co., U.S.A.). The obtained results were as follows : 1. The tensile bond strength of cast posts made by Duralay resin patterns revealed 39.13(kg) with Panavia-EX, 46.40(kg) with phosphate cement, and 37.78(kg) with glass ionomer cement. 2. The tensile bond strength of cast posts made by wax patterns revealed 39.25(kg) with Panavia, EX, 44.12(kg) with phosphate cement, and 40.23(kg) with glass ionomer cement. 3. The tensile bond strength of cast posts made by Duralay resin patterns or wax patterns were not affected by the type of dental cements(P>0.05).

• Journal of Environmental Science International
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• v.9 no.2
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• pp.145-149
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• 2000

The purpose of this study was to determine whether Vermi Cast could be used effectively to remove $SO_2$ from flue gas, and then to investigate optimum adsorption conditions. The Vermi Cast used as adsorbent was mechanically screened with 8~20 mesh sieve. The adsorption data for $SO_2$ were regressed using the Freundlich isotherm. The fit was generally satisfactory ($R^2$=0.945~0.982). With the temperature changes from 2$0^{\circ}C$ to 4$0^{\circ}C$, the constant k in Freundlich isotherm qe= $kCe^{1/n}$, decreased from 1.409 at 2$0^{\circ}C$to 0.297 at 4$0^{\circ}C$, and the exponent 1/n were decreased from 0.343 to 0.134. With the bed depth changes from 10cm to 30cm, the adsorption capacity expressed as mmol of $SO_2$ adsorbed per g of Vermi Cast increased from 0.247 to 0.381. Moisture content is an important parameter in the $SO_2$ adsorbed were observed over 0.3mmol $SO_2$ /g Vermi Cast. The best adsorption capacity was 0.487mmol $SO_2$ /g Vermi Cast, and it was obtained with moisture content 37%, temperature 2$0^{\circ}C$. From the above results, ti might be concluded that Vermi Cast is effectively as a good adsorbent to remove $SO_2$ from flue gas.