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전자선 용해법에 의한 V 의 정련 및 용해에 관한 연구
김휘준,백홍구,윤우영,이진형,강춘식 ( Hwi Joon Kim,Hong Koo Baik,Woo Young Yun,Zin Hyoung Lee,Choon Sik Kang ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.3
N/A In order to improve the production process of low cost and high purity Vanadium, this study was done to reduce V₂O_5 into V-Al master alloy by Aluminothermic Reduction, followed by refining of V-Al master alloy electron beam melting. As melting time was increased in electron beam melting of V, the contents of interstitial impurities and Al, Fe were decreased but the contents of Si, Mo and W were increased due to lower vapor pressure of these elements than that of matrix V. Consequently, it was profitable that melting of V was done for 180 seconds. In addition, with number of melting, the purity of V did not significantly vary, because volatile impurities in V were removed mostly during the first step of melting. As a result of V refining by electron beam melting, high purity Vanadium of 3N(99.91wt%) was acquired including interstitial impurities total contents of which were maximum 400ppm.
Ar / Ar-H2 플라즈마 및 전자선 용해에 의한 인바 및 퍼멀로이 Fe-Ni 합금의 정련
박병삼,백홍구 ( Byung Sam Park,Hong Koo Baik ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.2
N/A It is difficult to remove such interstitial impurities as sulfur, oxygen, hydrogen and carbon in Fe-Ni alloys. Thermodynamic and kinetic studies were carried out on the behavior of hydrogen gas, oxygen gas, Si, Al and slag, and the reaction time by the Ar/Ar-H₂ plasma and electron beam melting. After the addition of Al, Si, they were melted by Ar plasma with reaction time changed. 80%Ni-Fe alloys showed a better deoxidation than 36%Ni-Fe alloys. At Ar-H₂ plasma melting, the deoxidation was significant. In the case of the electron beam melting, the residual oxygen was higher than in Ar plasma melting because electron beam melting temperature was lower than that of Ar plasma. For the decaburization, it was melted by Ar-O₂plasma melting, which could remove effectively carbon by activated oxygen in plasma. We added slag to Fe-Ni alloys for the desulfurization. As the result of this experiments, the amount of residual sulfur was not changed according to the slag ratio and reaction time.
정역 회전법에 의한 고순도 알루미늄의 응고 및 정련에 관한 연구
김욱,이종기,백홍구,허성강 ( Wook Kim,Joung Ki Lee,Hong Koo Baik,Seong Gang Heo ) 한국주조공학회 1992 한국주조공학회지 Vol.12 No.3
N/A The degree of purification and the macrostructure of high purity aluminium were studied through the alternate stirring method in order to improve the nonuniformity of solute concentration in the unidirectional stirring method. The 2³factorial design was done to examine the effects of experimental factors more qualitatively. In the relatively low stirring speed of 1500 rpm with alternate stirring mode, the uniform solute profile and refined grain structure were obtained due to strong washing effect and turbulent fluid flow. It was induced by the transition of the momentum boundary layer by alternation of the stirrer. It was concluded from this study that the alternate stirring mode was more effective to obtain the uniformity of solute even in the stirring speed of 1500 rpm. But the degree of purification decreased below the critical alternating period. When 2N(99.8wt.%) aluminium was used as the starting material the morphology of solid-liquid showed the cellular shape and the columnar grains were inclined to the direction of rotation. This inclined grain growth resulted from the difference of relative velocities of solid and liquid. The inclined angle was increased as the stirring speed increased and solidification proceeded. In the case of 4N aluminium, there was no inclined grain growth and it was confirmed from the macrostructure and SEM work that the morphology of solid-liquid interface was planar. From the factorial design, it was found that the alternate stirring mode showed poorer purification effect than that of unidirectional stirring mode at low speed(500 rpm). In addition, the factor that had the most significant effect on the degree of purification was the stirring speed.
냉각체 회전법에 의한 고순도 알루미늄 및 규소의 응고 및 정련에 관한 연구
김욱,이종기,백홍구,윤우영 ( Wook Kim,Jong Ki Lee,Hong Koo Baik,Woo Young Yoon ) 한국주조공학회 1991 한국주조공학회지 Vol.11 No.4
N/A The Purification mechanism of high purity aluminum was studied through the variation of stirring speed and coolant flow rate in the stirring method. In the stirring method the degree of purification was changed as the following factors :the variation of diffusion boundary layer thickness the variation of growth rate and the solute concentration of the residual melt. The concentration of Fe and Si was decreased as the stirring speed and the radial distance increased. In a high stirring speed of 2000rpm with unidirectional stirring mode, the uniformity of solutes was obtained. On the other hand, the purification of Si was done by the combinations of stirring method, fractional melting and acid leaching. In the case of Si purification, the centrifugal force developed in the melt acted as the significant purification factor. It was possible to obtain the purified 3N grade Si crystal after the complete elimination of residual aluminum by fractional melting and acid leaching.
리튬 미소전지용 $LiCoO_2$ 박막양극의 전기화학적 특성에 미치는 기판의 영향
이종기,이승주,백홍구,이성만,Lee Jong-Ki,Lee Seung-Joo,Baik Hong-Koo,Lee Sung-Man 한국전기화학회 2000 한국전기화학회지 Vol.3 No.3
기판의 변화가 박막전극의 전기화학적 특성에 미치는 영향을 조사하기 위해 박막 $LiCoO_2$ 양극을 alumina, chemically etched-Si그리고 flat-Si기판 위에 증착하였다. Alumina기판의 경우 산소 분위기, $800^{\circ}C$ 30분간 열처리 후 내부에 균열이 존재하는 매우 큰 결정이 형성되었으나 flat-Si 기판의 경우에는 미세하며 균일한 결정이 관찰되었다. Flat-Si 기판 위에 증착된 박막은 alumina또는 식각된 Si 기판의 경우에 비하여 peak potential증감 및 고 전류밀도 방출 능면에서 매우 우수한 특성을 나타내었으며 이는 열처리 후 형성된 결정립의 크기, 표면 형상 및 전류 집전체의 전기저항 차이에 기인한 것으로 생각되었다. In order to investigate the substrate effect on the electrochemical properties of thin-film electrode, $LiCoO_2$ was deposited onto the alumina, chemically etched-Si and flat-Si substrates. After annealing at $800^{\circ}C$ in $O_2$ for 30min, the film deposited on the alumina consisted of large particles with several cracks, whereas the film deposited on the flat-Si substrate was composed of very small and uniform particles. The films deposited on the flat-Si showed improved electrochemical properties such as peak potential divergence and rate-capability, over those deposited on the alumina and chemically etched-Si substrate, which can be attributed to the differences of the particle size surface morphology, and the electrical resistance of the current collector.
수직 Bridgman 법에 의한 CdTe 단결정 성장에 관한 연구
이종기,김욱,백홍구 ( Jong Ki Lee,Wook Kim,Hong Koo Baik ) 한국주조공학회 1990 한국주조공학회지 Vol.10 No.4
N/A The single crystal of CdTe was grown by modified 6 zone Bridgman method under the conditions of excess Te and excess Cd. To prevent the constitutional supercooling, the crystal growth was done under the temperature gradient of 17℃/㎝ in front of the solid /liquid interface and the growth rate was 3㎜/hr. The grain morphologies and the growth mechanism were investigated in excess Te and excess Cd conditions. The grain size of excess Te crystal was increased with an increase of the distance from the tip but, in the case of excess Cd crystal, single crystal was not obtained because of the cavities due to the excess Cd vapors so that the grain size was not increased with an increase of the distance from the tip. In addition, the growth of single crystal of CdTe was done with repeated necking ampoule. It was found that the necking had no effects on the grain selection because the cavities trapped in the necking portion acted as heterogeneous nucleation sites.
이온선 혼합에 의한 Al / Pd계의 상형성 및 전이에 관한 열역학적 연구
최정동(Jeong Dong Choi),홍진석(Jin Seok Hong),곽준섭(Joon Seop Kwak),지응준(Eung Joon Chi),박상욱(Sang Wook Park),백홍구(Hong Koo Baik),채근화(Keun Hwa Chae),정성문(Sung Mun Jung),황정남(Chung Nam Whang) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.2
Al/Pd 계에서 이온선 혼합에 의한 초기 상형성 및 상전이를 연구하기 위하여 Al(500 Å)/Pd (200 Å)/glass 이중박막을 제작하여 여러가지 이온선량으로 80 keV의 에너지를 가진 Ar^+을 주입시켰다. RBS, TEM 등을 이용하여 이온선에 의한 혼합양상 및 상분석을 행하였다. 상온에서 이온선 혼합법에 의해 초기에 형성된 Al₃Pd₂는 이온선량이 증가함에 따라 Al₃Pd₂ 뿐만 아니라 AlPd상이 형성됨을 알 수 있었다. 유효생성열 (ΔH') 개념을 이온선 혼합에 의한 상형성 및 전이에 도입하여 초기 Al₃Pd₂ 형성 및 AlPd상으로서 상전이를 예측하였으며, 이러한 예측은 실험결과와 매우 일치함을 알 수 있었다. 금속/금속계 뿐만 아니라 금속/실리콘계에 대해서 이온선 혼합에 의한 초기 상형성 및 상전이에 관한 연구 및 실험이 현재 진행 중에 있다. Evaporated Al/Pd thin films were irradiated with various doses to produce intermetallic compounds. In order to study the first phase formation and phase sequence, RBS and TEM studies have been used. It was found that the initial phase formed by irradiation of 5×10^(15)Ar^+/㎠ was Al₃Pd₂, while 1.5×10^(16)Ar+/㎠ gave the subsequent phase of AlPd. This phenomenon was analysed using effective heat of formation (ΔH') model. The experimental results agree with that predicted by effective heat of formation model. This model has been extended to predict the first phase formation and phase sequence by ion beam mixing in metal/Si systems as well as metal/metal systems.
무기 박막을 이용한 이온빔 배향 FFS 셀의 전기광학특성에 관한 연구
황정연,박창준,정연학,김경찬,안한진,백홍구,서대식,Hwang, Jeoung-Yeon,Park, Chang-Joon,Jeong, Youn-Hak,Kim, Kyung-Chan,Ahn, Han-Jin,Baik, Hong-Koo,Seo, Dae-Shik 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.10
In this paper, we intend to make fringe-field switching (FFS) mode cell by the ion beam (IB) alignment method on the a-C:H thin film, to analyze electro-optical characteristics in this cell. We studied on the suitable inorganic thin film for fringe-field switching (FFS) cell and the aligning capabilities of nematic liquid crystal (NLC) using the alignment material of a-C:H thin film as working gas at 30 W rf bias condition. A high pretilt angle of about 5 $^{\circ}C$ by ion beam (IB) exposure on the a-C:H thin film surface was measured. Consequently, the high pretilt angle and the good thermal stability of LC alignment by the IB alignment method on the a-C:H thin film surface as working gas at 30 W rf bias condition can be achieved. An excellent voltage-transmittance (V -T) and response time curve of the IE-aligned FFS-LCD was observed with oblique IB exposure on the a-C:H thin films. Also, AC V-T hysteresis characteristics of the IB-aligned FFS-LCD with IE exposure on the a-C:H thin films is almost the same as that of the rubbing-aligned FFS cell on a polyimide (PI) surface.