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용탕단조한 과공정 Al-Si 합금(A390)의 미세조직과 기계적 성질
주대헌,신희택,김명호 ( Dae Heon Joo,Hee Teak Shin,Myung Ho Kim ) 한국주조공학회 1996 한국주조공학회지 Vol.16 No.1
N/A The effects of squeeze casting process on the microstructure and mechanical properties of hypereutectic Al-Si alloy have been studied. The effect of T6 heat treatment has also been examined. The mold for indirect squeeze casting was designed to fabricate 15ø and 25ø specimens and the 50ø specimen was fabricated by direct squeeze casting. The measured cooling rates during solidification of 50ø, 25ø and 15ø specimens are about 36℃ /sec., 88℃/sec. and 106℃/sec., respectively. There were no clear difference in size and distribution of primary Si particles of the A390 alloy modified at 850℃ with P(Cu-P) additions in 15ø and 25ø, 50ø squeeze cast specimens. However, the size and distribution of primary Si particles of the A390 alloy modified at 800℃ were found to be affected by cooling rates during solidification. A further important observation was that eutectic structure was greatly refined by pressure application during solidification and the eutectic Si of 15ø specimen was finer than that of 25ø and 50ø specimens. Due to the microstructural refinement, mechanical properties of 15ø specimen were found to be better than those of 25ø and 50ø ones. After T6 heat treatment, the mechanical properties were remarkably improved.
중소도시 아파트단지 방범계획의 CPTED 요소 적용에 관한 연구
반상철(Bahn, Sang-Chul),신희택(Shin, Hee-Taek) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.2
도시의 인구집중 결과로 공동주택의 비중이 지속적으로 증가하는 추세에 있다. 이러한 도시화의 진전과 함 께 과밀화되고 있는 공동주택단지를 대상으로 한 여러 유형의 범죄가 증가하고 있다. 공동체 의식의 소멸과 익명성의 증가 및 출입통제의 곤란은 물론 주거동의 배치계획 등에서 방범에 관한 점이 거의 고려되고 있지 않은 등의 결과로 대부분의 공동주택단지가 범죄에 대한 방어에 매우 취약한 환경에 놓여 있는 실정이다. 본 연구에서는 이러한 점에 주목하여 원천적인 범죄예방의 방안을 모색하기 위해 실제 주거단지를 대상으로 단지의 환경설계를 통한 범죄예방의 적용가능성을 모색해 보고자 하였다. 이를 위해 CPTED의 개념과 내용을 분석하고, 해외 선진사례를 조사하였다. 또 한 현 주거단지의 방범상 문제점의 파악과 물리적 기법의 적용가능성을 분석해 보았다. 그 대상은 중소도시에 입지한 공동주거단지 중 근래 가장 수요가 많은 30평형대의 규모가 위주인 단지를 선정하였다. 건축과 도시설계의 단계에서 CPTED의 기법을 적용하는 범죄예방 환경설계 측면의 물리적 수단을 모색해보는 것은 추후 공동주택단지의 계획에 기초자료로서 의미를 가질 수 있을 것이며, 유지관리의 측면에서는 공동체의 강화가 안 전한 주거환경의 지속가능성을 제고하는 기반이 된다는 점도 중요한 계획요소로 고려되어야 할 것이다. In Contemporary residential area, especially apartment commplex, crime affect the quality of life and sustainability of cities. So our interest is an all-time high in the role that planning processes and the design of the physical environment can play in reducing the opportunity for crime. The purpose of this study try to find the possibility of application of CPTED in Urban Apartment Complex. Recently, as increase of residencial density, diverse and new types of crime are increasing in urban apartment complex. It is the current of times which demand our serious consideration. This research focused on crime reduction through the physical environmental control methods. And the concepts and contents of CPTED are studied and the case studies of developed countries are surveyed. For groping in the practical application, researched into the case study of apartment blocks in medium sized city, Cheongju. Also Local crime prevention initiatives require partnership working, both between professionals and with local communities. The result of this study has implicated, increasing importance on daily safety issue in urban life and examining the possibility of applying crime prevention and reduction program and systems.
CaCN2 첨가에 의한 AM60 마그네슘 합금의 결정립 미세화 및 기계적 성질
엄정필,정승규,임수근,신희택,정득수 ( Jeong Pil Eom,Seong Kyu Jeong,Su Geun Lim,Hee Taek Shin,Deuk Soo Jeong ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.4
N/A Effects of CaCN₂ addition on the grain refinement in the AM60 magnesium ingots were investigated. The effects of the CaCN₂ are estimated with different inoculation temperatures, inoculation contents, and holding time to find out the optimum condition. AM60 alloy was melted in the low carbon steel crucible by cylindrical electric furnace under an argon atmosphere. The melting and casting apparatus is specially designed for magnesium alloys. The grain size of AM60 magnesium alloy decreased significantly with an increase in CaCN₂ content and, at 0.8 wt% CaCN₂ or more, grain size becomes constant at about 85 ㎛. The optimum condition was obtained in the 0.8 wt% CaCN₂ for holding molten metal of 30 min. at the temperature of 710˚C. The tensile properties of AM60 magnesium alloys were improved due to grain refinement by addition of CaCN₂. In the optimum condition, the yield strength, tensile strength and elongation were σ_(0.2)= 107 MPa, σ_(T.S)=234 MPa and e=14.2%. The variation of stress with strain obeyed the relationship of the σ= Kε^n. The strain-hardening exponent, n and strength coefficient, K obtained in the 0.8 wt% CaCN₂ added AM 60 magnesium alloy were n=0.21 and K=390 MPa. (Received May 28, 1998)
Am60 마그네슘 합금의 결정립 미세화에 미치는 탄소접종제 C2Cl6 첨가의 영향
엄정필(Jeong Pil Eom),정승규(Seong Kyu Jeong),임수근(Su Geun Lim),신희택(Hee Taek Shin) 한국주조공학회 1999 한국주조공학회지 Vol.19 No.3
The effects of C₂Cl_6 addition on the grain refinement of AM60 magnesium alloy were investigated. AM60 alloy was melted in the low carbon steel crucible by cylindrical electric furnace under an argon atmosphere. The effects of the C₂Cl_6 were estimated with various inoculation temperatures, inoculation contents, and holding times to find out the optimum conditions. The grain size of AM60 magnesium alloy decreased significantly with an increase in C₂Cl_6 content and, over 0.6 wt% C₂Cl_6 or more, grain size constant at about 94 ㎛. The optimum condition was obtained in the 0.6 wt% C₂C_(16), holding for 30 min. at 740˚C The tensile properties of AM60 magnesium alloys were improved due to grain refinement by the additions of C₂Cl_6 In the optimum condition, the yield strength, tensile strength and elongation were σ_(0.2) = 107 MPa, σ_(T.S) = 231 MPa and e = 1 4%, respectively. The variation of stress with strain obeyed the relationship of the σ= Kε^n. The strain-hardening exponent, n, and strength coefficient, K were n = 0.22 and K = 380 MPa. (Received March 30, 1999)