• 헤리티지:역사와 과학
• /
• 제53권1호
• /
• pp.168-183
• /
• 2020

기원전 5세기부터 중국에서는 주조철기의 사용을 늘리기 위해 주조철기 특유의 취성(脆 性)을 제거하려 노력해 왔다. 그중 한 가지는 주조철기를 생산한 다음 별도의 가마에서 풀림열처리를 하는 기술이다. 이 기술은 조직 내 탄소를 응집하거나 제거해, 주조철기의 취성을 제거하고 단조(鍛造)를 가능하게 만드는 것이다. 풀림열처리 기술의 실체를 명확히 하기 위해 현재의 제철 기술 및 중국·일본의 연구 성과를 바탕으로 한반도 출토 고대 주조철기 가운데, 풀림열처리 기술이 확인된 가단주철제 주조철기를 검토하였다. 그 결과 원삼국시대 이전까지 가단주철제 주조철기는 모두 외부로부터 수입된 것으로 추정된다. 또한 일본 이시가미신궁에 소장 중인 칠지도가 한반도에서 제작된 것으로 본다면, 4세기에 들어서야 백제에서는 풀림열처리 기술을 확보했을 가능성이 있다. 하지만 당시에는 괴련철을 중심으로 철 생산이 이루어졌으며, 괴련철을 정련한 괴련강을 소재로 다량의 단조철기가 제작되었다. 또한 기존의 주조철기 중 주조괭이를 제외한 대부분의 주조철기가 단조철기로 대체되었다. 따라서 삼국시대까지 풀림열처리 기술은 많이 사용되지 못하였다. 하지만 통일신라시대에 들어서 철 생산 및 유통의 지역 거점인 장안리 유적에서 확인될 정도로 기술이 확산된 것을 확인하였다.

• 대한기계학회논문집A
• /
• 제24권3호
• /
• pp.777-785
• /
• 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.

• 환경위생공학
• /
• 제14권1호
• /
• pp.97-102
• /
• 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.

• 한국주조공학회지
• /
• 제5권3호
• /
• pp.5-12
• /
• 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.

• 한국주조공학회지
• /
• 제1권2호
• /
• pp.2-9
• /
• 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.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 2005년도 한국우주과학회보 제14권2호
• /
• pp.59-59
• /
• 2005

• 헤리티지:역사와 과학
• /
• 제53권2호
• /
• pp.4-23
• /
• 2020

이 연구는 우리나라 철 주조기술의 다양성과 기술 체계를 규명하기 위한 목적으로 진행되었으며, 이를 위해 고문헌 조사 및 유물 분석, 제작 도구와 제작 기술에 대한 현지 조사 그리고 주조와 거푸집에 사용된 재료의 과학 분석 등을 실시하였다. 불미기술은 송풍구인 풀무를 이용하여 주철을 녹인 뒤 그 쇳물을 토제 거푸집에 부어 주물을 완성하는 철 주조기술로 현재 유일하게 제주도에서만 전승되고 있는데, 모래 거푸집을 사용하는 육지와 비교해 토제 거푸집을 사용하고 있다는 것이 큰 차이점이라 할 수 있다. 무쇠솥 주조기술에는 석비레, 모래, 점토 등을 섞어 만든 모래 거푸집을 이용한 주물사주조법(鑄物砂鑄造法)과 점토에 볏짚과 갈대 등을 섞어 만든 토제 거푸집을 이용한 도토주조법(陶土鑄造法)이 사용되고 있다. 주물사주조법에 의한 무쇠솥 주조는 거푸집 만들기, 속심 제작, 쇳물 작업, 거푸집에 쇳물 붓기, 완성품 다듬기 등 5단계의 작업공정을 거치며, 도토주조법에 의한 무쇠솥 주조는 거푸집 만들기, 거푸집 굽기, 질먹 입히기, 쇳물 작업, 쇳물 붓기, 완성품 다듬기 등 크게 6단계의 작업 공정으로 이루어진다. 두 주조법은 거푸집의 재료, 거푸집을 불에 굽고 질먹을 입히는 제작 공정에서 차이를 보인다. 이번에 연구한 불미기술은 토제 거푸집 무쇠솥 주조로 진흙 채취 및 반죽, 거푸집 제작, 초벌 굽기, 화적모살 및 질먹 바르기, 건조 및 비얄질, 거푸집 합장, 둑(용광로)제작, 재벌 굽기, 제련, 쇳물 붓기, 주물 다듬기 등 단계별 주조 공정에 사용된 재료 및 도구 분석과 제작 기술에 담겨진 과학 기술 원리를 규명하여 우리 고유 철 주조기술의 기술 체계를 밝혀 보았다. 그리고 무쇠솥 도토주조를 위해 이용한 재료와 완성품을 과학 분석한 결과, 거푸집은 주성분이 SiO₂, Al₂O₃, Fe₂O₃으로 이루어진 진흙과 모래이고, 이형재는 SiO₂, Al₂O₃, Fe₂O₃, K₂O가 함유된 흑연이며, 완성된 무쇠솥의 미세 조직은 시멘타이트(Fe₃C)와 펄라이트(페라이트와 시멘타이트의 층상 구조)로 이루어진 백주철 조직임을 확인하였다.

• 대한치과보철학회지
• /
• 제36권6호
• /
• pp.858-866
• /
• 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).

• 대한치과보철학회지
• /
• 제31권4호
• /
• pp.461-467
• /
• 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).

• 한국환경과학회지
• /
• 제9권2호
• /
• pp.145-149
• /
• 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.