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윤광민(Gwangmin Yoon),강동하(Dongha Kang),고영진(Youngjin Ko),임종대(Jongdae Lim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
High level vacuum die casting (HLVD) allows the casting products heat treatable with aid of minimized gas contents (e.g. max 3cc/100gAl), therefore it shows improved mechanical properties. In order to decrease the gas content of castings, vacuum level in cavity should be maintained under 5kPa during mold filling process. For the quality control of mass production, the practical inspection system should be required in the production process. In this study, we have focused on finding the relationship between process parameters and gas porosity, one of the main casting defects. We developed thin walled bracket with HLVD process to achieve weight reduction as well as cost saving. In addition, improved mechanical properties and productivity were acquired.
윤광민(Kwang Min Yoon),임지연(Ji Yeon Lim),김이준(Iee Joon Kim),김응모(Ung-mo Kim) 한국정보과학회 2011 한국정보과학회 학술발표논문집 Vol.38 No.1C
최근 기업들이 취업이나 승진에서 영어 말하기 능력을 중시하는 경향이 커지면서 영어권 국가로의 어학연수를 고려하는 학생들이 급격히 증가하고 있다. 어학연수에는 결코 적지 않은 비용이 소요 되며 적게는 3개월에서 많게는 1년 이상의 시간을 들여야 하므로 어학연수 프로그램의 선택에 매우 신중을 기해야 할 것 이다. 웹 상에는 이러한 어학연수 프로그램들에 대한 정보나 의견을 교환할 수 있는 수많은 커뮤니티 및 포럼들이 존재하며, 기 이용자들이 작성한 이용기 및 의견 게시물 또한 헤아릴 수 없이 많이 존재한다. 어학연수를 떠나고자 하는 대다수의 사람들은 이러한 웹 사이트에서 기존 이용자들의 이용기를 접하고 선택여부를 결정하고자 할 것이다. 하지만 이 수많은 게시물들을 모두 읽어보고 결정한다는 것은 너무나 많은 시간과 노력이 소모되게 된다. 이에 본 논문에서는 웹서버에 저장되어 있는 수많은 이용기를 오피니언 마이닝하고, 어학연수 프로그램에 대한 속성을 카테고리 별로 분석하여 이를 수치화해서 신규 이용자가 적은 시간과 노력으로 프로그램을 결정할 수 있도록 도와 줄 수 있는 방법을 제안하고자 한다.
윤광민(Gwangmin Yoon),김민수(Minsoo Kim),고영진(Youngjin Ko),임종대(Jongdae Lim) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Aluminum alloys play and important role in the weight reduction of the automobiles because of excellent combination of strength, cost and specific weight. So, the major car maker increase the aluminum chassis components. In this study, Cast-foring process applied to achieve very good productivity, high strength and lower cost than aluminum hot forging. As a result of this study, 45% weight reduced(compare to the steel product) and had good mechanical properties and productivity aluminum rear carrier is achieved.
알루미늄 나노입자분산형 알루미늄-천이금속-희토류금속 (또는 천이금속) 계 비정질합금의 기계적특성
김영환,김인배,윤광민,정병호 대한금속재료학회(대한금속학회) 1996 대한금속·재료학회지 Vol.34 No.6
The mechanical properties and thermal stability of amorphous Al_(88)Ni_9(Fe,Zr)₃and Al_(88)Ni_(10)(Y,Ce)₂ alloys produced by single roller melt-spinning method were investigated. Amorphous alloys containing nanoscale Al particles which are obtained by aging treatment in the temperature range above the crystallization temperature(T_x) exhibited σ₁ and H_v higher than those of amorphous single phase alloys with the same composition. T_x in the mixed phase alloys increased significantly with rising aging temperature. This indicates that the precipitation of the Al nanoparticles thermally stabilizes the remained amorphous matrix. The H_v for the mixed alloys increased monotonically with increasing the precipitation amount(V_f) of the Al phase. The σ₁and ε₁ showed a maximum value in an optimum V₁ value. This is probably thought because the Al nanoparticles which have higher mechanical strength compared with the amorphous matrix with the same composition act as an effective resistance to shear deformation of the amorphous matrix. The amorphous Al_(88)Ni_9Fe₃ exhibited combined effect of the dispersion strengthening and a large elongation resulted from the precipitation of the Al nanoparticles at elevated temperature.
김영환,김인배,윤광민,배동수 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.5
The structure, mechanical property and thermal stability of rapidly solidified aluminum-transition metal (=Fe, Co, Zr) alloy system were investigated. The structure was changed from Al phase to amorphous one through a mixed structure consisted of Al and amorphous phases with solute content. The amorphous single phase was formed at the Al-rich compositional range of Al=87-88at%. The crystallization temperature(T_x,) of amorphous Al_(88)Ni_(12-x)(Fe,Co)_x(X≤6at%) alloys was increased with the content of Fe or Co, indicating the thermal stabilization of the amorphous phase. Hardness (H_v,) and tensile fracture strength (σ_f) exhibited a maximum at the 5at% Fe or Co. On the other hand, aging treatment at temperature range less than 500K in amorphous Al_(88)Ni_9(Co,Fe)₃ alloys formed aluminum nanoparticles distributed homogeneously in an amorphous matrix. The H_v for the mixed phase alloy increased monotonically with the V_f. The σ_f showed a maximum at about 15%V_f and with further increase of the V_f decreased due to the embrittleness of the amorphous matrix. The increase is presumed because the Al particles act as an effective barrier to shear deformation of the amorphous matrix. The ultimate tensile fracture strength at elevated temperature less than 480K in an amorphous Al_(88)Ni_8Zr₃ alloy kept a high level more than 650㎫ and exhibited a large elongation of 25% at 440K. The large elongation can be explained by crystallization-induced plasticity.
원가 절감형 신주조 응용 기술에 의한 엔진 마운팅 브라켓 제조
오수석(Su Suk Oh),윤광민(Kwang Min Yoon),고영진(Young Jin Ko),김진우(Jin Woo Kim) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Since sand casting has advantages in that it can be manufactured with low cost mold and simple process it is one of the best way to produce aluminum or a small quantity of casting part. But it has relatively coarse microstructure, and as a result, the mechanical properties, particularly the tensile strength and ductility, were inferior to those of metal mold casting. To overcome these disadvantages, we suggested vacuum assisted low pressure sand casting process which uses evacuated die cavity during mold filling and processing. In this study the effects of vacuum assistance on the mechanical properties and porosity distribution of the produced castings were studied. And it was found that the density of gas porosity in the castings was significantly reduced and the mechanical property was improved to the same level as squeeze-cast parts by using vacuum assistance. Considering these merits, vacuum assisted low pressure sand casting is promising technology to produce sand cast parts not only because of sound casting quality but also because of cost effectiveness.