http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
304 스테인리스강 용접금속의 열처리에 따른 응력부식균열
조대형,김형래,남태운 ( D . H . Cho,H . R . Kim,T . W . Nam ) 한국열처리공학회 1996 熱處理工學會誌 Vol.9 No.1
Austenite stainless steel was produced by arc welding with current 650A, voltage 50V and welding speed 10㎝/min. It was post-welded and then heat treated at 1,050℃ for 120min. And then it was immersed in water or in air. The microstructural changes, ferrite contents, mechanical properties, and stress corrosion cracking(SCC) were investigated. The SCC was studied in 42wt% boiling MgCl₂(140℃) under the constant stress using SCC elongation curve. The results showed that; 1. The as-welded spedimen seemed to increase δ-ferrite content largely, and revealed continuous network of lathy and vermicular type. The post-welded heat treatment changed the morphologies of ferrite from continuous type to island type. 2. The as-welded, air and water quenched specimens had the δ-ferrite content 9.7%, 3.2% and 2.1% respectively. We also showed that ferrite was Cr-rich and Ni-poor by EPMA. 3. The time of failure on the SCC was measured and it was used for corrosion elongation curve. The condition of SCC was investigated under 35㎏f/㎟ load and the results were as follows; 도표 4. The intergranullar cracking by stress corrosion was most distinct in weld metal while the transgranular cracking occurred in the air cooled specimen.
이차원 전이금속 칼코겐화합물 반도체 소재 및 소자 기술개발 동향
윤선진,임정욱,조대형,정용덕,Yun, S.J.,Lim, J.W.,Cho, D.H.,Chung, Y.D. 한국전자통신연구원 2014 전자통신동향분석 Vol.29 No.6
수 원자층 두께의 전이금속 칼코겐화물 이차원 반도체 소재는 스위칭 소자 등에 활용하기에 적합한 밴드갭 에너지를 가지며, 높은 이동도와 우수한 광반응성으로 인해 최근 큰 관심을 끌고 있다. 특히 이차원 소재이므로 dangling bond가 없다는 점, 구조적 안정성, 실리콘에 뒤지지 않는 고이동도, 직접천이 특성 등으로 인해 차세대 전자소자용, 더 나아가 실리콘 반도체 대체 소재로써의 가능성도 점쳐지고 있다. 본고에서는 전이금속 칼코겐화물 이차원 반도체의 소재 특성과 제조방법, 소자 응용면에서의 기술개발 동향, 시장전망 등에 대해 소개하고, 이 소재가 현재 기대하는 만큼 중요하게 활용되고 기술이 발전하기 위해서 반드시 해결해야 할 숙제 등에 대해 논의하고자 한다.
급속응고에 의해 제조된 Fe-Nd-C 합금의 자기적 특성
장태석,임광윤,조대형,Jang, T.S.,Lim, K.Y.,Cho, D.H. 한국재료학회 1997 한국재료학회지 Vol.7 No.12
급속응고법으로 Fe-Nd-C 합금을 제조하여 합금의 조성 및 제조 조건의 변화에 따른 상변화와 자기특성의 변화를 조사하였다. 강자성 $Fe_{14}Nd_2C_x$가 초정으로 정출할 수 있는지를 알아보기 위하여 냉각속도의 변화에 따른 as-spun 합금에서의 상변화를 조사해 본 결과,10m/s로 제조한 Fe-Nd-C 리본합금은 ${\alphs}-Fe$가 일차상, $Fe_{17}Nd_2C_x$가 이차상으로 존재하는 결정질이었으며. 20m/s에서는 ${\alpha}-Fe$의 정출이 억제되거나 비정질화하여, $Fe_{14}Nd_2C_x$가 일차상, ${\alpha}-Fe$가 이차상으로서 비정질상과 함께 존재하였다. 냉각속도의 증가에 따라 비정질화가 증가하여 30m/s에서는 대부분 비정질화되었으며,40m/s에서 비정질화가 완료되었다. 따라서 $Fe_{14}Nd_2C$는 as-spun 상태에서는 얻어지지 않고 주조합금의 경우와 마찬가지로 열처리를 통한 고상변태에 의해서만 얻을 수 있었다. $Fe_{14}Nd_2C$를 얻을 수 있는 유효온도구역은 주조합금의 경우보다 넓은 $700{\sim}900^{\circ}C$였고,비정질화가 완벽한 합금보다 다소 덜 완벽하거나 $Fe_{17}Nd_2C_x$와 비정질상이 혼합된 합금에서 열처리에 의한 보자력의 향상이 더욱 현저하였다. Fe를 다량 함유한 Fe-Nd-C 조성 중에서 높은 보자력이 기대되는 조성 범위는 극히 제한되어, $750{\sim}800^{\circ}C$에서 몇 분간의 열처리로 10kOe 이상의 높은 보자력을 얻을 수 있는 조성은 77~78 Fe, 7~8 C (at.%) 정도였다. For me1t-spun Fe-Nd-C alloys, variation of phase development and magnetic properties with the variety of alloy compositions and production conditions were investigated. To find out whether hard magnetic $Fe_{14}Nd_2C$ is crystallized direct1y from the melt by rapid quenching, the phase development of the as-spun ribbons spun at various speed was a1so studied. For the ribbons spun at 10m/s, ${\alpha}-Fe$ was the primary crystallization phase followed by the secondary $Fe_{17}Nd_2C$. At 20m/s ${\alpha}-Fe$ was suppressed so that the primary $Fe_{17}Nd_2C$ coexisted with the secondary ${\alpha}-Fe$ and the amorphous phase. Above 30m/s the ribbons were a1most amorphous, and the amorphization was complete at 40m/s. $Fe_{14}Nd_2C$ therefore was not found in as-spun state but obtained after heat treating the ribbons. The effective temperature range ($700{\sim}900^{\circ}C$) in which $Fe_{14}Nd_2C$ can be obtained was wider than that of a cast alloy. An alloy made with the wheel speed of 20 or 30m/s yielded higher coercivities after heat treatment. In iron-rich Fe-Nd-C, the composition range in which a high coercivity (more than 10kOe) is expected is narrow, i.e., 77~78 Fe and 7~8 C(at.%).
이우정,황태하,조대형,정용덕,W.J. Lee,T.H. Hwang,D.H. Cho,Y.D. Chung 한국전자통신연구원 2023 전자통신동향분석 Vol.38 No.1
Topological insulators (TIs) emerge as one of the most fascinating and amazing material in physics and electronics. TIs intrinsically possess both gapless conducting surface and insulating internal properties, instead of being only one property such as conducting, semiconducting, and insulating. The conducting surface state of TIs is the consequence of band inversion induced by strong spin-orbit coupling. Combined with broken inversion symmetry, the surface electronic band structure consists of spin helical Dirac cone, which allows spin of carriers governed by the direction of its momentum, and prohibits backscattering of the carriers. It is called by topological surface states (TSS). In this paper, we investigated the TIs materials and their unique properties and denoted the fabrication method of TIs such as deposition and exfoliation techniques. Since it is hard to observe the TSS, we introduced several specialized analysis tools such as angle-resolved photoemission spectroscopy, spin-momentum locking, and weak antilocalization. Finally, we reviewed the various fields to utilize the unique properties of TIs and summarized research trends of their applications.
화합물 반도체 CIGS 박막태양전지 제작 및 특성 평가
김제하(J. Kim),조대형(D. -H. Cho),변태준(T. -J. Byun),정용덕(Y. -D. Chung),박래만(N. -M. Park),김은아(E. -A. Kim),이규석(K. -S. Lee),오수영(S. Y. Oh) 대한전자공학회 2010 대한전자공학회 학술대회 Vol.2010 No.6
We developed processes of co-evaporation and precursor-reaction for high quality CuIn,GaSe2(CIGS) and characterized their structural properties using various techniques such as SEM, XRD, XRF, and Auger depth profiling. In addition, we used a basic fabrication process for CIGS photovoltaic devices and evaluated their J-V characteristics. For the cells of 0.47 cm<SUP>2</SUP>, the conversion efficiency of 15.54% and 9.7% was obtained for co-evaporated and precursor-reaction prepared CIGS cells, respectively.
0.5wt% 탄소강을 이용한 해안 야외부식시험과 염수분무시험,가속부식시험의 가속계수에 대한 연구
조의열 ( E Y Cho ),권기봉 ( G B Gwon ),조대형 ( D H Cho ),김종렬 ( J Y Kim ) 한국부식방식학회 2013 Corrosion Science and Technology Vol.12 No.5
In the industry, accelerated corrosion test is used for the life time prediction. When anti-corrosion test proceeds in real environments, it is difficult that we predict and evaluate the corrosion life time because of the long test time such as 10 years or more time. Accelerated corrosion test and Salt spray test are able to test corrosion life time of products in the laboratory instead of outdoor corrosion test. Experimental procedure is selected for the corrosion standard specimen, exposure of the specimens, measurements of the mass loss and evaluating the mass loss data. As a result, the acceleration factor of the accelerated corrosion test to the outdoor corrosion test is 414.8. Therefore we can predict the corrosion life time of carbon steel during a short time period.