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기계적 합금화법으로 제조된 과포정 Al-Ti합금에서 Al3Ti 형성에 관한 연구
김혜성,서동수,김긍호,금동화 ( Hye Sung Kim,Dong Soo Suhr,Gyeung Ho Kim,Dong Wha Kum ) 한국열처리공학회 1996 熱處理工學會誌 Vol.9 No.1
Mechanical alloying is an effective process to finely distribute inert dispersoids in an Al-TM(TM is a transition metal) system. It has been considered that high melting point aluminides are formed by precipitation from supersaturated Al(Ti) powder. This analysis is based on the fact that much higher content of TM than the solubioity can be dissolved in alpha aluminum during the high energy ball milling. Thus, decomposition behavior of Ti in the Al(Ti) was considered very important. But it is confirmed that the higher portion of Ti than Al(Ti) solid solution is existed as nano-sized Ti particles in the MA powders by high energy ball nilling from the XRD spectrum and TEM analysis in this study. Therefore, the role of undissolved TM particles affect the formation of aluminides should be suitably considered. In this study, we present experimental observation on the formation of Al₃Ti fron mechanical alloyed Al-Ti alloys in the hyperperitectic region. This study showed that, in the mechanically alloyed Al-20wt%Ti specimen, intermediate phase of cubic Al₃Ti and tetragonal Al_(24)Ti_8 formed at 300∼400℃ and 400∼500℃, respectively, before the MA state reaches to equilibrium at higher temperatures. The formation behavior of Ll₂-Al₃Ti is interpreted by interdiffusion of A1 and Ti in solid state based on the fact that large amount of nano-sized Ti particles exist in the milled powder. Present analysis indicated undissolved Ti particles of nanosize should have played an important role initiation the formation of Al₃Ti phase during annealing.
기계적 합금화법에 의해 제조된 Al+Al3Ti합금 및 Al+10wt.%Ti합금의 고용현상
김혜성,이정일,김긍호,금동화,서동수( Hye Sung Kim,Jung Ill Lee,Gyeung Ho Kim,Dong Wha Kum,Dong Soo Shur ) 한국열처리공학회 1996 熱處理工學會誌 Vol.9 No.2
The solubility of Ti in Al matrix was determined by X-ray diffraction method on two different mechanical alloying systems, i.e Al+Al₃Ti and Al+Ti alloys. Starting powder compositions of two systems were chosen for final volume fraction of Al₃Ti phase being 25%. The solubility of Ti in α-Al was estimated by the lattice parameter measurement of Al. For Al+Al₃Ti mixture, it appeared that some of Al₃Ti particles decomposed during milling and maximum solubility of Ti in A1 was about 0.99%. The majority of Al₃Ti particles were dispersed uniformly in Al matrix, having approximate size of 100∼200㎚. On the other hand, higher Ti solubility of 1.24 wt.% was found in Al+Ti system, with starting composition of Al+10 wt.%Ti. After 15 hours of milling, Ti phase was identified as 20㎚ sized particles embedded in Al matrix. The annealing of mechanically alloyed powders from Al+Al₃Ti and Al+10 wt.%Ti systems was followed in the temperature range of 200 to 600℃ to study thermal stability of supersaturated solution of Al(Ti). After annealing, the lattice parameter of A1 reverted back to that of pure Al, and the peak intensity ratio of Al₃Ti/Al was increased more than the original value before annealing. These results suggest that Ti dissolve into alpha-Al solutions during milling, and by annealing, Do_(22)-Al₃Ti phase forms from Al(Ti) solution.
가스분사 분말로부터 고온 압출된 Al-Ni-Mm-(Cu, Fe)합금들의 미세구조 및 기계적 성질
김혜성,Kim, Hye-Sung 한국재료학회 2006 한국재료학회지 Vol.16 No.2
The effects of Cu and Fe additions on the thermal stability, microstructure and mechanical properties of $Al_{85}-Ni_{8.5}-Mm_{6.5},\;Al_{84}-Ni_{8.5}-Mm_{6.5}Cu_1,\;Al_{84}-Ni_{8.5}-M_{m6.5}Fe_1$ alloys, manufactured by gas atomization, degassing and hot-extrusion were investigated. Gas atomization, with a wide super-cooled liquid region, allowed the alloy powders to exhibit varying microstructure depending primarily on the powder size and composition. Al hotextruded alloys consisted of homogeneously-distributed fine-grained fcc-Al matrix and intermetallic compounds. A substitution of 1 at.% Al by Cu increased the thermal stability of the amorphous phase and produced alloy microstructure with smaller fcc-Al grains. On the other hand, the same substitution of 1 at.% Al by Fe decreased the stability of the amorphous phase and produced larger fcc-Al grains. The formation of intermetallic compounds such as $Al_3Ni,\;Al_{11}Ce_3\;and\;Al_{11}La_3$ was suppressed by the addition of Cu or Fe. Among the three alloys examined, the highest Vickers hardness and compressive strength were obtained for $Al_{84}-Ni_{8.5}-M_{m6.5}Cu_1$ alloy, and related to the finest fcc-Al grain size attained from increased thermal stability with Cu addition.
김혜성,윤성원,Kim, Hye-Seong,Yoon, Sung-Won 한국공간구조학회 2010 한국공간구조학회지 Vol.10 No.1
국내에 설치될 강구조 스타디움에 향후 신재생에너지 중 하나인 태양광 발전을 위한 PV 시스템을 적용하는 것에 따른 강재 어레이에 관한 기초 연구로 해외의 사례를 토대로 구성되었다. 연구를 진행하기 위하여 1990년대 이후 PV 시스템이 적용된 강구조 스타디움 20건을 사례 분석 대상으로 선정하였다. 선정된 20건의 강구조 스타디움을 PV 모듈을 고정하기 위하여 설치된 레일 시스템에 따라 분류해 보았다. 그 결과 격자고정방식 중 선형모듈고정방식과 지붕 통합형이 전체의 28%에 해당되는 것으로 조사되었으며 그 뒤로 레일 고정형 17%, 세로 고정방식 중 모듈그룹 고정 11% 순으로 조사되었다. 또한 스타디움 내부에는 주로 격자 고정방식 중 선형모듈 고정방식과 지붕통합형이 적용되고 있었으며 스타디움 외부나 그 외 부분에서는 앵글 브라킷으로 PV 모듈이 고정되고 있는 것으로 조사되었다. This paper focuses on steel arrays regarding the application of PV system for solar power system, a renewable energy in steel structure stadium that will be built in Korea, by foreign case study. 20 cases of Steel Structure Stadiums applying PV system after 1990 were selected as the main subjects. The 20 cases of Steel Structure Stadiums were categorized by rail systems that were installed to fix PV module. As the result, linear clamping and roof-integrated type among cross rails were 28% of the whole, followed by 17% of rail-fixed type and 11% of module group-fixed type among vertical-fixed types. In addition, linear clamping and roof-integrated type among cross rails were applied in the inside of the stadium while the outside and other parts of stadiums used angle bracket to fix PV module.
김혜성 ( Hye Sung Kim ) 한국주관성연구학회 2015 주관성연구 Vol.- No.31
본 연구는 에이즈 예방 인식을 유형화한 연구이다. 에이즈에 특히 취약계층이라고 할 수 있는 청년들을 대상으로, Q 방법론을 활용하여 분석하였다. 분석 결과, 에이즈 관련 정보가 별로 없으나 긍정적인 인식과 태도의 ‘용감한 참여자’형(1유형), 두려움과 거부감을 가진 ‘도망가는 겁쟁이’형(2유형), 관련 정보와 지식을 가졌으나 소극적인 ‘지혜로운 방관자’형(3유형) 등, 세 개의 유형을 발견하였다. 그리고 각 유형별 특징과 차이점 확인하였다. 연구결과, 관련 정보와 지식의 부족이 에이즈에 대한 편견으로 나타나지만, 자발적 예방행동 참여 의도는 정보, 지식 유무와 상관없이 형성되는 것이 확인 되었다. 본 연구의 의미는 에이즈 예방캠페인에서 다루어야 할 세부적인 내용을 유형화 하여 구체적으로 제시 하였다는데 있다. This study examined the patterns of perceptions regarding the prevention of AIDS among college students who could be vulnerable to AIDS. The results of this study employing the Q-methodology indicate that three patterns of collegestudents’ perceptions regarding the prevention of AIDS emerge: the first type is characterized by brave individuals who does not have much information regarding AIDS but have positive perceptions and attitudes toward AIDS; the second type is characterized by cowards who are fear for AIDS and whose perceptions and attitudes toward AIDS are unfavorable; and (3) the third type is characterized by knowledgeable bystanders who have much information on AIDS but are passive. Additionally, this study shows the similarities and differences across these three types. The results indicate that the lack of information and knowledge makes individuals have a prejudice against AIDS; however, individuals tend to voluntarily participate in preventing AIDS regardless of their level of information and knowledge. This study provides specific information that needs to be addressed in future AIDS prevention campaigns.