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.

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.

사례분석에 의한 강구조 스타디움 레일 시스템 분류

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.

대학생의 에이즈 예방 인식 유형에 대한 연구

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.

RBCC 추진기관 비행시험을 위한 과학로켓 임무 분석

김혜성(Hye-Sung Kim),양원석(Won-Seok Yang),김귀순(Kui-Soon Kim),오세종(Se-Jong Oh),최정열(Jeong-Yeol Choi) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12

세계 각국에서는 군사 또는 과학의 목적으로 다양한 극초음속 비행체 연구 개발 프로그램이 진행되고 있으며, 관련 기술 확보를 위해 소형 발사체나 미사일을 부스터로 사용하는 비행시험 프로그램이 대두되고 있다. 호주는 HyShot 비행시험 프로그램의 뒤를 이어 미국과 협력하여 HIFiRE 프로그램을 수행하고 있으며, 국내에서도 스크램제트 기반 추진기관에 관한 다양한 연구가 이루어지고 있다. 이에 따라 본 논문에서는 향후 수행될 RBCC 추진기관 비행시험에 필요한 과학로켓 임무 분석을 수행하였으며, 그 결과 현재 국내에서 사용되고 있는 발사체 중 KSR-Ⅱ가 가장 적합할 것으로 예측하였다. Various R & D programs of hypersonic flight vehicle are progressed with the purpose of military or science worldwide and hypersonic flight test programs using missile or small launch vehicle are on the rise to acquire technologies. Australia is conducting HIFiRE program with USA after HyShot flight test program, and domestic studies of propulsion system based in scramjet are progressed. Accordingly, this paper designs and analyzes a mission of sounding rocket for flight test with RBCC propulsion system to be performed in the future, and shows that KSR-Ⅱ is a best launch vehicle fitted for the mission among domestic launch vehicles now in use.

수렴성 빔 전자회절 도형을 이용한 Al-Ti 합금의 상 분석

김혜성(Hye-Sung Kim) 한국산업융합학회 2001 한국산업융합학회 논문집 Vol.4 No.2

The use of primitive cell volume and zero order Laue (ZOLZ) pattern is proposed to identify phase in a complex microstructure. Single convergent beam electron pattern containing higher order Laue zone ring from a nanosized region is sufficient to calculate the primitive cell volume of the phase, while ZOLZ pattern is used to determine the zone axis of the crystal. A computer program is used to screen out possible phases from the value of measured cell volume from convergent beam electron diffraction (CBED) pattern. Indexing of ZOLZ pattern follows in the program to find the zone axis of the identification from a single CBED pattern. An example of the analysis is given from the rapidly solidified AI-Al₃Ti system.<br/> <br/> <br/>

CD 로 복각된 유성기 음반 해제 및 목록

김혜성(Hye Sung Kim) 한국고음반연구회 2001 한국음반학 Vol.- No.11

N/A

연구논문 - 복합재료 - : In - Situ 복합재료로서의 과포정 Al - Ti 합금

김혜성(Hye Sung KIm),김긍호(Gyeung Ho Kim),금동화(Dong Wha Kum) 대한금속재료학회(구 대한금속학회) 1994 재료강도 심포지엄 Vol.- No.-

과학로켓 및 소형 발사체를 이용한 준궤도 극초음속 비행시험 프로그램

김혜성(Hye-Sung Kim),양원석(Won-Seok Yang),최정열(Jeong-Yeol Choi) 한국항공우주학회 2015 韓國航空宇宙學會誌 Vol.43 No.3

극초음속 비행체 개발 연구의 일환으로 소형 발사체나 과학로켓을 이용한 여러 비행 시험 프로그램이 진행되었다. 국제 협력으로 진행된 호주의 HyShot 프로그램은 과학로켓을 이용한 대표적인 스크램제트 엔진 비행시험 프로그램이며, 이후 다양한 탑재체에 대한 유사한 극초음속 비행 시험 프로그램들이 진행되었다. 미국에서는 DARPA와 AFRL 및 ONR이 각각 Falcon HTV-2, X-51A 및 HyFly의 프로그램을 수행하였으며, 호주와 국제협력으로 HyCAUSE, HIFiRE 비행시험 프로그램을 수행하였다. 그 밖에도 프랑스는 X-51A과 유사한 LEA 프로그램을 진행하고 있으며, 러시아 및 중국, 인도는 극초음속 방위 체계 개발을 목표로 비행시험을 진행하고 있는 것으로 보인다. 본 논문에서는 향후 국내에서 유사 프로그램을 수행할 시 참고할 수 있도록, 이들 프로그램의 목표 및 기술 요소와 경과 및 프로그램 사이의 관계 등을 정리하였다. As a part of the R&D efforts for the hypersonic vehicles, various flight test programs has been carried out using small launch vehicles or sounding rockets. Australian HyShot program is a representative case of the flight test program for scramjet engines carried by international collaborations. A number of hypersonic flight test programs has followed in a similar way. In USA, Falcon HTV-2 was carried by DARPA, X-51A by AFRL and HyFly by ONR. HyCAUSE and HIFiRE were carried in collaboration with Australia. In France, LEA program is on the way similarly to X-51A. Russia, China and India seems like carrying out flight test programs for the development of hypersonic defense system. The goals, technical elements, the status and the relation between the programs were summarized in this paper as a reference for the similar program of the country in the future.