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SCHOTTKY PROPERTIES OF ION BEAM DEPOSITED W-Si-N REFRACTORY CONTACTS ON GaAs
Park, C. S.,Lee, J. S.,Yang, J. W.,Shim, K. H.,Lee, J. H.,Choe, Y. K.,Kang, J. Y.,Ma, D. S.,Lee, J. Y. 대한전자공학회 1989 ICVC : International Conference on VLSI and CAD Vol.1 No.1
We first tried low energy ion beam assisted deposition (IBAD) of refractory W-Si-N films onto GaAs for application to gate electrode of metal-semiconductor field effect transistors (MESFET). This ion beam technique provides lower process pressure, and less ion damage to substrates and films than conventional reactive sputter-deposition. The Schottky diode characteristics of W-Si-N contacts on GaAs and their thermal stability were investigated after annealing at 700-900℃ for 30 min. The Schottky barrier heights of W/, WN_(0 27)/, and WSi_(0 3)N_(0 4)/GaAs diodes annealed at 850 were 0.71, 0.84, and 0.76 eV respectively, which are comparable to those of the best results obtained by the conventional sputtering.
Lim, J.H.,Shim, J.H.,Choi, J.H.,Park, J.H.,Kim, W.,Joo, J.,Kim, C.J. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15
We fabricated nano-carbon (NC) doped MgB<SUB>2</SUB> bulks using an in situ process in order to improve the critical current density (J<SUB>c</SUB>) under a high magnetic field and evaluated the correlated effects of the doped carbon content and sintering temperature on the phase formation, microstructure and critical properties. MgB<SUB>2-x</SUB>C<SUB>x</SUB> bulks with x=0 and 0.05 were fabricated by pressing the powder into pellets and sintering at 800<SUP>o</SUP>C, 900<SUP>o</SUP>C, or 1000<SUP>o</SUP>C for 30min. We observed that NC was an effective dopant for MgB<SUB>2</SUB> and that part of it was incorporated into the MgB<SUB>2</SUB> while the other part remained (undoped), which reduced the grain size. The actual C content was estimated to be 68-90% of the nominal content. The NC doped samples exhibited lower T<SUB>c</SUB> values and better J<SUB>c</SUB>(B) behavior than the undoped samples. The doped sample sintered at 900<SUP>o</SUP>C showed the highest J<SUB>c</SUB> value due to its high doping level, small amount of second phase, and fine grains. On the other hand, the J<SUB>c</SUB> was decreased at a sintering temperature of 1000<SUP>o</SUP>C as a result of the formation of MgB<SUB>4</SUB> phase.
붐 형상 변화에 따른 컨테이너 크레인 구조 안정성의 실험적 해석
이성욱(S. W. Lee),한동섭(D. S. Han),심재준(J. J. Shim),한근조(G. J. Han),김태형(T. H. Kim) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월
This study was carried out to analyze the effect of wind load on the structural stability of a container crane according to the change of the boom shape using wind tunnel test and provide a container crane designer with data which can be used in a wind resistance design of a container crane assuming that a wind load 75m/s wind velocity is applied in a container crane. Data acquisition conditions for this experiment were established in accordance with the similarity. The scale of a container crane dimension, wind velocity and time were chosen as 1/200, 1/13.3 and 1/15. And this experiment was implemented in an Eiffel type atmospheric boundary layer wind tunnel with 11.52㎡ cross-section area. Each directional drag and overturning moment coefficients of a container crane according to the change of the boom shape were investigated.
이재영,남수우,심상희 대한금속재료학회(대한금속학회) 1980 대한금속·재료학회지 Vol.18 No.3
Ni-hard의 凝固後 冷却速度가 耐磨耗性에 미치는 影響이 考察되었다. 또한 殘留 austenite가 tempering에 依하여 bainite로 變態되었을 境遇 耐磨耗性에 미치는 影響도 考察되었다. 本 實驗의 結果에 依하면 Ni-hard는 凝固後 徐冷이 始作되는 溫度가 上昇될수록 硬度도 上昇하며 約 650℃에 이르면 冷却途中 austenite內의 炭素濃度가 平衡狀態에 到達하여 殘留 austenite가 最少가 되며 따라서 最高硬度에 이르게 되는 것으로 보인다. 殘留 austenite를 tempering에 依하여 bainite로 變態시키면 一般的으로 硬度의 增加가 나타나나 磨耗時 磨耗表面에서 殘留 austenite의 martensite 變態가 나타날 수 없으므로 耐磨耗度는 오히려 떨어진다고 보인다. Scratch test에 依하여 grain size가 耐磨耗性에 미치는 影響을 조사한 結果 旣存 磨耗式은 다음과 같이 變形되어질 수 있으리라 보인다. V= (K"W·L/H)·1/N^¼ After solidification Ni-hard, the effects of cooling rate on abrasive wear resistance are investigated. When most of retained austenite is transformed to bainite by tempering, the change of abrasive wear resistance is also investigated. The heardess of Ni-hard increases with increasing the temperature from which slow cooling begins. But the hardness remains at the maximum value even though the temperature gets over about 650℃. This may mean that when the temperature is about 650℃ or above, the carbon concentration of austenite comes to be near equilibrium. By tempering, retained austenite is transformed to bainite and hardness is increased. But the wear resistance of this transformed Ni-hard is lower than that of original one. It may be because of the fact that the transformed Ni-hard has much less retained austenite to be transformed to martensite by wear at abrading surface than original one. Using scratch test, the effect of grain size to wear resistance was investigated. As a result, the existing abrasive formula may be modified as follow: V= (K"W·L/H)·1/N^¼ N : numoer of carbide or aggregate grains in a unit area of wear surface.