주조연결된 니켈-크롬-베릴리움 주조체의 굽힘강도에 관한 비교연구

정창모,전영찬,임장섭,Jeong, Chang-Mo,Jeon, Young-Chan,Lim, Jang-Seop 대한치과보철학회 1998 대한치과보철학회지 Vol.36 No.6

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).

카스트에 대한 관심 변화와 이슈 트렌드 분석

신진영 한국아시아학회 2022 아시아연구 Vol.25 No.3

Caste has been a hot topic for a long time and is still attracting attention in India. Nevertheless, studies analyzing the notions and change of caste all over India, are lacking so far. In this regard, the study examines changes in interest levels and analyzes key issues and trends that have led to changes in caste across India through big data. The data collection period for this study is from January 1, 2009 (Internet users in India exceeded 5.1%) to December 31, 2021. For the research, ① caste search volume, ② related search terms, ③ search volume of related search terms, and ④ related search terms and volume from 'google trends' were collected and analyzed during the period. The analysis results are as follows. First, the search volume for caste has steadily increased. Second, caste-related issues are classified into ① caste certificate, ② caste notions, ③ caste category, ④ marriage and religion, and the core of caste-related issues are identified as the caste-based affirmative action and system(Reservation for SC, ST and OBC). Third, caste-related issues tend to be practical and specific. In conclusion, caste is still a topic of interest among Indians, and it will be difficult to disappear from Indian society for the time being since it is closely related to daily practical issues.

컴퓨터 시뮬레이션을 이용한 임플란트 상부 티타늄 구조물의 주조방안

오세욱,이호용,이근우,심준성,Oh Se-Wook,Lee Ho-Yong,Lee Keun-Woo,Shim Jun-Sung 대한치과보철학회 2003 대한치과보철학회지 Vol.41 No.4

Statement of problem : It is difficult to obtain a good titanium casting body using the traditional sprue design because of high melting point of Ti, and the low fluidity and high reactivity of molten Ti. Purpose : A new sprue design for titanium casting bodies needs more trial and error. In order to decrease the number of trial and error, computer simulation(MAGMASOFT, Magmasoft Giessereitechnologie GmbH, Achen, Germany) was used to optimize sprue design in U-shaped implant superstructures. Material and method : Five kinds of sprue were examined for the design of the sprue former for titanium casting: Sprue design A(sprue length 4 mm, rectangular shape, 4 sprues), Sprue design B(sprue length 4 mm. round shape. radius 2 mm, 7 sprues), Sprue design C (sprue length 2 mm, round shape, radius 2 mm, 7 sprues). Sprue design D (sprue length 2 mm, cone shape, large radius 3mm. small radius 2mm, 7 sprues), and Sprue design E( sprue length 2 mm. one unit channel shape). Sprue design F(sprue length 2mm, one unit channel shape) was also examined for the design of the customized sprue former in the Biotan system(Schutz Dental Gmbh, Germany). The casting bodies were taken in Sprue design A, Sprue design D, Sprue design E, and Sprue design F in the Biotan casting system. The numerically predicted defects were compared with the experimental dental castings by the radiographic and sectional view observations. Results : 1. According to the result of computer simulation, turbulence during mold filling was decreased in the sequence of Sprue design F, Sprue design E, Sprue design D, Sprue design C, Sprue design B, and Sprue design A. 2. The calculated solidification time contours indicate that hot spot was moved from the casting body to the sprue button in the sequence of Sprue design A, Sprue design B, Sprue design C, Sprue design D, and Sprue design E. The filling pattern of Sprue design F was similar to that of Sprue design E. 3 The predicted filling pattern shows that less turbulence was found in the customized sprue former than in the standard sprue former. 4. According to the results of the radiographic and cross sectional observations, casting defects less than 1mm were found at the center of a casting body with Sprue design E and Sprue design F. However, larger casting defects of 4mm were found in a casting with Sprue design A. 5. The predicted casting porosity was similar to that of the real casting. Conclusion : One unit channel-type and customized sprue former can be recommended. Further research and developement of various sprue designs using computer simulation in necessary to optimize casting design, in order to reduce the formation of casting defects in implant titanuim super-structures.

현대 네팔의 카스트 제도와 소득 및 사회적 자본 상관관계 연구 -티카플 지역 사례연구-

김장생 한국종교학회 2019 宗敎硏究 Vol.79 No.1

The purpose of this paper is to examine how the caste system in Nepal correlates with the income and the social capital. This paper analyses the current status and characteristics of the caste system in Nepal and the relationship between the caste system and inco me and social capital in Tikapur, Nepal. The results of the analysis are as follows. First, the lower caste has the higher proportion of farmers. Agricultural income is lower than other occupations, so the lower caste has the lower income. Second, the caste system strengthens social cooperation and trust within the lower group. Unfair treatment and oppression from the higher castes strengthens the co-operation and cohesion within the lower castes. Third, the caste system does not affect community identity and value sharing. The inter cooperation among castes is weakened due to the exclusive attitude to other castes. Finally, the faith is manifested not through social relations, but through the inner religiosity of the individuals. This study contributes to find the correlation between the caste and income and also extends the scope of the research on income and the caste to the agricultural sector. 카스트 제도는 베다와 마누 법전에 뿌리를 두고 있는 힌두교 사회신분제도로서 네팔 주민들의 경제 및 사회적 활동에 큰 영향을 미치고 있다. 지금까지 네팔의 카스트 제도와 관련된 연구는 많이 이루어 졌으나, 농업 소득 및 사회적 자본과 카스트 제도와의 관계에 대한 연구는 거의 발표되지 않았다. 본 논문의 목적은 현대 네팔의 카스트 제도가 주민들의 소득 및 사회적 자본과 어떠한 상관관계를 가지고 있는가를 알아보는 것이다. 이를 위하여 논문은 첫째, 네팔 카스트 제도의 현황 및 특징을 알아보았고 둘째, 주제에 대한 선행연구들을 살펴보았으며 마지막으로 티카플에서 수집한 데이터 분석을 통하여 카스트와 소득 및 사회적 자본의 관계를 분석하였다. 분석 결과는 다음과 같다. 첫째, 하위 카스트 일수록 농민이 많고 농업 소득은 타직종에 비하여 낮음으로 결국 하위 카스트일수록 소득이 적었다. 둘째, 카스트 제도는 주민 간 협동과 협력 그리고 신뢰에 음으로 영향을 미쳤다. 상위 카스트로부터의 부당한 대우가 하위 카스트의 내적 응집력을 높여 집단내의 상호 협동과 협력이 강화된 것으로 해석된다. 셋째, 카스트 제도는 지역사회의 정체성과 가치 공유에는 영향을 미치지 못하였다. 카스트 내 응집력이 카스트간 응집력으로는 발전되지 못하였던 것이다. 마지막으로 힌두교 신앙심은 사회적 관계 보다는 개인의 내적 종교심과 관계를 가지고 있었다. 본 연구의 의의는 아직 까지 선행연구가 이루어지지 못하고 있는 카스트 제도와 사회적 자본의 상관관계를 실증연구를 통하여 분석하고 또한 주로 임금 노동이 주를 이루는 카스트와 소득의 상관관계의 연구 지평을 농업소득까지 확장함으로서 네팔 주민들에게 미치는 힌두교 카스트 제도의 영향을 더욱 정교화 할 수 있었다는 데서 찾을 수 있다.

석고주형 진공주조법을 활용한 기물 제작 사례 연구

조성호 사단법인 한국조형디자인협회 2018 조형디자인연구 Vol.21 No.4

Investment Casting (Lost Wax Casting) is the most generally used casting method for jewelry and metal forming. Vacuum casting we are using, a kind of Investment Casting, is also classified as a plaster mold technique due to its molding materials. The production cost is lower than other casting methods but not suitable for the production of larger sized vessels due to the constraints arising from equipment issues. Therefore, other casting methods are chosen rather than using vacuum casting for various vessels beyond the appropriate scale. However, vacuum casting is suitable for obtaining precise and complicated results. Moreover, it can easily produce a single or even mass production. Above all, the distribution of vacuum casting equipment is remarkably superior to other casting; therefore if various vessels can be produced by vacuum casting, considerable gain can be expected. Accordingly, the technical characteristics and development aspect of vacuum casting have been proactively analyzed and the works and making process of two artists, Lizzy Yoo and Peter Bauhuis, who have expanded the limits and possibilities of vacuum casting have been studied. Lizzy Yoo uses stone from nature as her motif and overcame the technical limits of vacuum casting by managing her works without any splitting of her object which is a significant factor in this research. In the case of Peter Bauhuis, he has used various alloys in casting outstandingly showing the maximized surface effects. It is strongly believed that this research will contribute in expanding possibilities of vessel making through vacuum casting and to free the technical constraints of size in casting. 정밀주조법(精密鑄造, investment casting 혹은 탈납주조(脫蠟鑄造, lost wax casting))는 장신구와 금속조형 작업에 활용되는 주조법 가운데 가장 일반적으로 사용되는 기법이다. 우리가 사용하고 있는 진공주조(眞空鑄造, vacuum casting)도 정밀주조의 한 종류로서 주형 재료(molding material)에 따라 주조법을 분류하면 석고주형(plaster mold)법에 속한다. 진공주조는 다른 주조법에 비해 제작비가 저렴하나 설비와 관련해서 발생하는 제약이 많다. 그래서 일정 규모 이상의 기물의 제작에는 적합하지 않은 기법으로 알려져 있다. 그러므로 큰 형태의 기물 제작에는 대부분 진공주조가 아닌 여타 주조법을 채택한다. 그러나 정밀하고 복잡한 입체 형태의 주물에 적합하고 일품생산과 대량생산에 모두 적용 가능하며, 무엇보다 설비의 보급률이 다른 주조법과 비교해 월등히 뛰어난 진공주조로 다양한 기물을 제작할 수 있다면 여러모로 이득일 것이다. 이에 진공주조법의 기술적 특성과 발전 양상에 관해 선제적으로 분석하고 진공주조를 통한 기물 제작의 범위와 가능성을 확장시킨 두 작가인 유리지와 페터 바우휘스의 작품과 그 제작 과정을 연구하였다. 유리지는 돌이라는 자연물을 조형적 모티브로 하여 큰 크기의 기물을 쪼갬 없이 제작함으로써 진공주조법의 기술적인 한계를 극복하였고, 페터 바우휘스의 경우 다양한 합금(alloy)을 주조에 사용함으로써 표면효과를 극대화했다는 점에서 주목할 만한 성과를 보여준다. 이와 같은 연구를 통해 금속 기물 제작 시 진공주조의 활용 가능성을 확대하고, 나아가 주물의 크기에 대한 기술적 제약으로부터 보다 자유로울 수 있는 기법을 개발하는데 기여하고자 한다.

Projection Method에 의한 주조 해석용 접촉 요소망 생성 기법

남정호 ( Jeong-ho Nam ),곽시영 ( Si-young Kwak ) 한국주조공학회 2020 한국주조공학회지 Vol.40 No.6

In general, hot metal castings contract and molds expand during the cooling step of a casting process. Therefore, it is important to consider both the casting and mold at the same time in a casting process analysis. For a more accurate analysis that includes the contact characteristics, matching each node of the casting and mold in the contact area is recommended. However, it is very difficult to match the nodes of the casting and the mold when generating elements due to the geometric problem of CAD model data. The present study proposes a mesh generation technique that considers mechanical contact between the casting and the mold in a casting analysis (finite element analysis). The technique focuses on the fact that the mold surrounds the casting. After generating the 3D elements for the casting, the surface elements of the casting in contact with the mold are projected inside the mold to create contact elements that coincide with the contact surface of the casting. It was confirmed that high-quality contact element information and a 3D element net can be automatically generated by the method proposed in this study.

장신구 정밀주조산업의 발전방안에 관한 연구

임옥수(Lim, ock - soo),임철민(Lim, chul - min) 한국조형디자인학회 2009 조형디자인연구 Vol.12 No.4

In Investment casting for jewelry manufacturing, pattern of polyelectrolyte form is made through an rapid prototyping and after it is formed as wax-pattern it is led to a final product or master pattern through investment casting. Accordingly most rapid prototyping is restricted to manufacturing of functional form, which makes products designed by 3D into polyelectrolyte material form. Thus this thesis aims to suggest efficient investment casting which simplifies the production processes of the investment casting used currently and the processes from producing polyelectrolyte original form to master pattern manufacturing process, which is a part of plans for the development of investment casting. This thesis also presents casting defects caused during the process of investment casting for manufacturing jewelry and the solutions for them. Most casting defects that happen in the process of manufacturing jewelry are caused by very small size and complex form of jewelry and these casting defects are led to mass production defects, which is significant disorder. This study, therefore, aims to help devise more various and creative manufacturing of jewelry by theoretically reviewing on casting defects and presenting solutions for them, and contribute to development and vitality of Korean Jewelry investment casting industry.

Numerical Optimization of the Method of Cooling of a Massive Casting of Ductile Cast-Iron

Jana Dobrovska,Frantisek Kavicka,Karel Stransky,Bohumil Sekanina,Josef Stetina 한국소성가공학회 2010 기타자료 Vol.2010 No.6

The numerical models of the temperature field of solidifying castings, according to various authors, have been observing two main goals ? directed solidification as the basic assumption for the healthiness of a casting and the optimization of the technology while maintaining the optimal product properties. The achievement of these goals is conditioned by the ability to analyze and, successively, to control the effect of the deciding factors, which either characterize the process or accompany it. An original application of ANSYS simulated the forming of the temperature field of a massive casting from ductile cast-iron during the application various methods of its cooling using steel chills. The numerical model managed to optimize more than one method of cooling but, in addition to that, provided serious results for the successive model of structural and chemical heterogeneity, and so it also contributes to influencing the pouring structure. The file containing the acquired results from both models, as well as from their organic unification, brings new and, simultaneously, remarkable findings of causal relationships between the structural and chemical heterogeneity (i.e. between the sizes of the spheroids of graphite, the cells, density of the spheroids of graphite, etc.) and the local solidification time in any point of the casting. The determined relations therefore enable the prediction of the face density of the spheroids of graphite in dependence on the local solidification time. The calculated temperature field of a two-ton 500x500x1000 mm casting of ductile cast-iron with various methods of cooling has successfully been compared with temperatures obtained experimentally. The casting was cast in sand mould. The calculated model of the kinetics of the temperature field of the casting was verified during casting with temperature measurements in selected points.This has created a tool for the optimization of the structure with an even distribution of the spheroids of graphite in such a way so as to minimize the occurrence of degenerated shapes of graphite, which happens to be one of the conditions for achieving good mechanical properties of castings of ductile cast-iron.

석고주형 진공주조법을 활용한 기물 제작 사례 연구

조성호(Cho, Sung–,ho) 한국조형디자인학회 2018 조형디자인연구 Vol.21 No.4

정밀주조법(精密鑄造, investment casting 혹은 탈납주조(脫蠟鑄造, lost wax casting))는 장신구와 금속조형 작업에 활용되는 주조법 가운데 가장 일반적으로 사용되는 기법이다. 우리가 사용하고 있는 진공주조(眞空鑄造, vacuum casting)도 정밀주조의 한 종류로서 주형 재료(molding material)에 따라 주조법을 분류하면 석고주형(plaster mold)법에 속한다. 진공주조는 다른 주조법에 비해 제작비가 저렴하나 설비와 관련해서 발생하는 제약이 많다. 그래서 일정 규모 이상의 기물의 제작에는 적합하지 않은 기법으로 알려져 있다. 그러므로 큰 형태의 기물 제작에는 대부분 진공주조가 아닌 여타 주조법을 채택한다. 그러나 정밀하고 복잡한 입체 형태의 주물에 적합하고 일품생산과 대량생산에 모두 적용 가능하며, 무엇보다 설비의 보급률이 다른 주조법과 비교해 월등히 뛰어난 진공주조로 다양한 기물을 제작할 수 있다면 여러모로 이득일 것이다. 이에 진공주조법의 기술적 특성과 발전 양상에 관해 선제적으로 분석하고 진공주조를 통한 기물 제작의 범위와 가능성을 확장시킨 두 작가인 유리지와 페터 바우휘스의 작품과 그 제작 과정을 연구하였다. 유리지는 돌이라는 자연물을 조형적 모티브로 하여 큰 크기의 기물을 쪼갬 없이 제작함으로써 진공주조법의 기술적인 한계를 극복하였고, 페터 바우휘스의 경우 다양한 합금(alloy)을 주조에 사용함으로써 표면효과를 극대화했다는 점에서 주목할 만한 성과를 보여준다. 이와 같은 연구를 통해 금속 기물 제작 시 진공주조의 활용 가능성을 확대하고, 나아가 주물의 크기에 대한 기술적 제약으로부터 보다 자유로울 수 있는 기법을 개발하는데 기여하고자 한다. Investment Casting (Lost Wax Casting) is the most generally used casting method for jewelry and metal forming. Vacuum casting we are using, a kind of Investment Casting, is also classified as a plaster mold technique due to its molding materials. The production cost is lower than other casting methods but not suitable for the production of larger sized vessels due to the constraints arising from equipment issues. Therefore, other casting methods are chosen rather than using vacuum casting for various vessels beyond the appropriate scale. However, vacuum casting is suitable for obtaining precise and complicated results. Moreover, it can easily produce a single or even mass production. Above all, the distribution of vacuum casting equipment is remarkably superior to other casting; therefore if various vessels can be produced by vacuum casting, considerable gain can be expected. Accordingly, the technical characteristics and development aspect of vacuum casting have been proactively analyzed and the works and making process of two artists, Lizzy Yoo and Peter Bauhuis, who have expanded the limits and possibilities of vacuum casting have been studied. Lizzy Yoo uses stone from nature as her motif and overcame the technical limits of vacuum casting by managing her works without any splitting of her object which is a significant factor in this research. In the case of Peter Bauhuis, he has used various alloys in casting outstandingly showing the maximized surface effects. It is strongly believed that this research will contribute in expanding possibilities of vessel making through vacuum casting and to free the technical constraints of size in casting.

금속활자 주조를 위한 蜜蠟鑄造法의 鑄物土 실험연구

이승철 한국서지학회 2006 서지학연구 Vol.34 No.-

Though the technology of casting movable metal types through lost-wax casting method has been theorized by previous researches, many tests and discussions have been continuously implemented for the purpose of identifying the soil of mold because of problems of its materials for experiments and mixture ratio.This study has an intention of identifying the kinds of proper natural materials, mixture ratio and physical characteristics for casting movable metal types through lost-wax casting method by experiment.To this end, the experiment was conducted with the following conditions and procedures, and the results of test were analyzed.1. Preparation for the Test1) Materials for making the mother letters : natural beeswax2) Casting materials : clay mixed with soft stones / mudstone, loess, sand3) Metal material : bronze, tin, lead2. Test procedure1) Carving the mother letters2) Casting the mold3) Melting the metal and making the types4) Trimming the types and Printing3. Analysis of the casting results1) Examination on casting materials2) Shape of movable metal types by materials3) Size variation of movable metal typesExperiments were conducted on casting the types with traditional casting materials to identify technology of casting movable metal types through the lost-wax casting. As a result, it was found that the problems of casting materials which have so far been much debated in the previous research were solved by using natural materials.Even though the test with natural materials was implemented successfully, lots of questions regarding the restoration process of casting metal types with the lost-wax casting method could be raised because how to cast metal types with the lost-wax casting method was not documented.For this, it is suggested that more research and tests for traditional casting method as well as the test for casting metal types should be conducted. 밀랍주조법에 의한 금속활자의 주조는 선행연구들에 의해서 지금까지 이론화되어 왔지만, 鑄型土의 고증에 있어서는 사용재료와 배합비율의 문제로 인해 많은 논의와 실험이 지속되고 있다. 본 연구는 밀랍주조법에 의한 금속활자 주조시 적절한 천연 주형재료의 종류와 배합비율, 물리적 특성 등을 고증하여 이를 실험해 보는데 그 목적이 있다. 이를 위해 다음과 같은 조건으로 실험을 진행하고 진행과정과 실험결과를 분석하여 보았다.