超耐磨耗 CLAD 積層材의 微細組織에 미치는 鎔接條件 및 熱處理의 影響

梁在雄,金在洙 대진대학교 1995 大眞論叢 Vol.3 No.-

We designed the overlay welding machine for cladding and tried to seek the conditions of optimum manufacturing process and develope the severe abrasive wear-resistance clad plate. The Overlay welding was performed by a autogeneous submerged arc welder equipped with cooling and JIG system to minimize the dilution of cladding metal and prevent the distortion of mild steel used as a base plate. Cladding metals were overlayed by single layer deposition onto the base plate with 9mm and 6mm thickness to form over 4mm deposit thickness by using one electrode Wire(dira ; 3.2mm) and agglomerated high alloyed fluxes. Investigation has been made through the chemical analysis, the microscope observation including optical, SEM and EDX and the microvickers hardness tester, first of all, to examine the changes of compositions of weld metal and those of microstructure and hardness from interface to surface according to variables of welding process such as welding current, arc voltage, travel speed and weaving width. Second, effects of heat treatments on microstructure and hardness of weld metal were examined. By using two fluxes, weld metals of white cast iron with each different composition were obtained. The hardness of Cladl (low C) with hypo-eutectic structure was HRC51 and that of Clad2 (high C) with hyper-eutectic structure was HRC62. The hardness was decreased with increasing the penetration ratio and decreasing the cooling effect. Hardness of annealed specimen was more decreased than as-weld specimen with increase of annealing temperature, while normalizing heat treatment didn't affect the hardness of specimen (Clad2), but increased the hardness of specimen (Clad1) as much as those of Clad2 due to the transformation to martensite of austenite in matrix.

배양 포유동물 세포에 인위적으로 삽입한 재조합 DNA의 복제에 관한 연구

양재섭,김길웅 대구대학교 기초과학연구소 1985 基礎科學硏究 Vol.2 No.-

The transformation of LMTK- to LMTK+ was performed with cell fusion and DNA blot hybridization. The chick erythrocytes were used in cell fusion, pJM 94 and chick erythrocyte DNAs were used in DNA blot hybridization. The frequency of transformation was less than 5 x 10-8 in tretment of pJM 94 and 2.5 x 10-6 in treatment of chick erythrocyte DNA. The frequency of cell fusion was 10-7. The TK genes of LMTK+ transformated by DNA blot hybridization well more stable than the TK genes of LMTK* transformated by cell fusion. It is thought that the very low frequency of transformation in treatment of pJM 94 was caused by absence of viral promoter and presence of yeast prometer in pJM 94 DNA.

밀봉유리-금속 계면의 산화층이 내전압 특성에 미치는 영향

양재웅 대진대학교 1998 大眞論叢 Vol.6 No.-

Glass-metal sealing has long been a primary method for hermetically isolating hybrid components from potentially harsh environments in which these devices are used. The hermeticity, strength and voltage breakdown of these seals directly effect the reliability of the components of which they are a part and, henceforth, can cause or prevent potentially catastrophic component failure, Furnace atmosphere requirements for both matched and compression types of sealing vary for the three production process steps; degassing, oxidation and sealing. The research presented here is centered around the precise control of the oxidation through the use of a humidified H₂O-H₂furnace atmosphere to investigate the effects of oxide layer formed at the glass-metal interface on voltage breakdown characteristics. To produce consistently reliable seals with the good voltage breakdown property, precise blending of the furnace atmosphere including H₂O-H₂gas mixture should allow repeatable limits in which the depth of oxide layer is determined below 11㎛. This improved process relies on more precise control over furnace atmosphere composition to produce a more reliable product at higher levels of consistency than have been previously realized by the industry.

Strip 육성용접에 의한 Clad 판재의 제조공정 및 미세조직에 관한 연구

양재웅 대진대학교 1996 大眞論叢 Vol.4 No.-

I designed the overlay welding machine for strip cladding and tried to seek the conditions of optimum manufacturing process and study the microstructures of the wear-resistance and the anti-corrosive clad plate. The overlay welding was performed by a autogeneous submerged arc welder equipped with cooling and JIG system to minimize the dilution of cladding metal and prevent the distortion of mild steel used as a base plate. Cladding metals were overlayed by single or double layer depositions onto the base plate with 9mm and 40mm thickness to form over 3mm deposit thickness by using each different strip electrodes (high Cr stainless strip and austenitic stainless strip) and agglomerated medium alloyed fluxes. First of all, I determined the optimum manufacturing conditions for strip cladding through the modified experimental modelling. Second, Investigation has been made through the chemical analysis, the microscope observation and the microvickers hardness tester to examine the changes of compositions, the crack susceptibility of weld metal and those of microstructure and hardness from interface to surface according to variables of welding process.

溶融鹽 中에서 鐵系素地金屬의 A1 메탈라이딩에 關한 硏究

梁在雄,安在禹,李煥哲 대진대학교 1995 大眞論叢 Vol.3 No.-

A new coating process known as metalliding has been adopted to have the diffusion coating of aluminium on steel from molten fluorides(29.2wt.% LiF-11.7wt.% NaF-59.lwt.% KF, FLINAK). Experiments were carried out in argon gas atmosphere. The electrolytic cell consists of a steel cathode and a consumable aluminium anode. The reagents were vacuum dried to remove the moisture for 24hrs. at 400 C and the electrolyte was pre-electrolyzed to remove residual impurities. The influence of the co-deposition of manganese was also investigated. The quality of deposit was analyzed by SEM, EPMA and also examined by Micro-Vickers hardness, and corrosion tests. Deposit layer was identified as an aluminium-rich iron alloy layer caused by diffusion process. The optimum condition for the metalliding was found to be the bath temperature, 575℃, the amount of AlF_(3), l0wt.%, and the current density, 50 to 150mA/cm^(2). Addition of manganese fluoride (up to 5wt.%) as a co-deposit element improved significantly the quality of deposit layer.

생쥐의 骨髓細胞에 대한 Aminopterin 과 Amethopterin의 細胞遺傳學的 影響

양재섭,강봉석,최명철,김길웅 대구대학교 기초과학연구소 1987 基礎科學硏究 Vol.4 No.-

Aminopterin and amethopterin(Methotrexate; MTX) are antifolic drugs and anti-tumour agents, which inhibit DNA biosynthesis, were previously known to have mutagenic effects on various mammalian cells. Mutagenecity and toxicity of these agents have been determined by various methods. In the present study, effects of two anti-tumour agents on cultured mouse bone marrow cells were analyzed by observing chromosome aberrations and mitotic index. The results of the present investigation were as follows; 1. The chromosome aberrations analyzed were mainly chromosome gaps and breaks, chromatid gaps and breaks. In the Group-1 (treated for 8 hours), chromosome aberrations were not shown and it seems that mutagenic actions of anti-tumour agents were not aroused due to the short period of culture and the other culture conditions. However, in the Group-2 (treated for 24 hours), as the concentrations of antifolic compounds were increased, chromosome aberrations were increased. 2. In mitotic index, the Group-I treated with aminopterin and amethopterin showed marked inhibition in the mitotic index(O. 6% in aminopterin, 0.9% in amethopterin) at the high concentrations, compared with that of control (5. 2%). Both aminopterin and amethopterin showed a dose-dependent reduction of mitotic index. In the Group-2, each group treated with two antifolic compounds showed no marked differences in the mitotic index. compared with that of control. 3. Aminopterin was a more potent agent for induction of chromosome aberration than amethopterin.

AOD 스테인레스 제강공정에서 CaO-Cr₂O₃ 슬래그 중 용존 Si에 의한 Cr₂O₃의 반응속도론

양재웅 대진대학교 2002 大眞論叢 Vol.10 No.-

The reduction rate of solid slag, CaO-Cr₂O₃ which is the reaction product formed at the oxidation period of A.O.D process was measured in the presence of residual Si at temperatures between 1600 and 1700℃. Synthetic solid slags of CaO-Cr₂O₃binary and also of ternary containing MgO or CaF₂ as additives were respectively prepared by compacting and sintering in a form of disk. Reduction experiments were carried out by adding Si into liquid metal pool and then placing the disk on it in a high frequency induction furnace. From results observed a reaction mechanism was proposed ; the reduction rate is controlled by a mixed process combining diffusion-out of Cr₂O₃ through liquid slag layer of CaO-Cr₂O-SiO₂ and the surface reaction on the liquid slag/liquid metal interface. Experimental activation energies, therefrom, were determined to be 63kcal/mole for the diffusion process and 152kcal/mole for the surface reaction. Effects of slag additives, such as MgO and CaF₂ on reduction of Cr₂O₃ were also discussed and favourable working conditions at the reduction period of the A.O.D process were suggested.

α-Fa를 含有한 뷔스타이트의 分解反應 및 速度에 關한 硏究

梁在雄 대진대학교 1993 大眞論叢 Vol.1 No.-

Decomposition reaction and kinetics of Wustite(Fe_(1-x)O) as functions of temperature, grain size and impurities have been investigated. The decomposition temperatures were 400℃ and 530℃. The mean grain diameters were 48μm, 37μm, and 28μm and the doped impurities were 3wt.% CaO and 3wt.% CoO, respectively. The decomposition mechanism of Wustite with metallic iron made by powder metallurgy was diffusion controlled by Fe^(2+) ion and the metallic iron acted as nuclei. The decomposition rate was greater at 400℃ than 530℃ and the magnetite(Fe₃O₄) precipitated primarily at 400℃, while the a-Fe precipitated primarily at 530℃. The Wustite decomposition rate increased as the grain size decreased at 400℃, while the rate of decomposition increased as the grain size increased at 530℃. The addition of CaO decreased the Wustite decomposition rate at 400℃, while the addition of CoO increased the rate.

고온 반사로 내의 온도분포에 관한 연구

양재웅 대진대학교 첨단소재연구소 2000 첨단소재연구소논문집 Vol.3 No.-

Rapid thermal furnace in which heating elements are IR(Infra-red) lamps is known as the good efficient heating furnace with a rapid heating and cooling, a good reliability and stability in service and a wide uniform zone at high temperature, thereby improving the value in use at severe atmosphere. These furnaces utilize 100% of the radiant heat emmitted by the lamps and thus are able to reach the high temperature in a much shorter period of time than the resistant heating furnaces. The heating elements are securely mounted on standard flanges in the curved reflection mirror coated by gold. It is important to know the temperature profiles and uniform zone on reaction tube in rapid thermal furnace as a basic data because there are many variables of heating sources such as conduction, convection, radiation and reflection. At this research, prepared furnace was tested by the thermocouples to investigate the thermal distribution through the reaction tube and compared in use of blackbody with in use of only lamp.

쾌삭 STD61 강에서 개재물의 성분 및 형태에 미치는 첨가원소의 영향

양재웅 대진대학교 첨단소재연구소 1999 첨단소재연구소논문집 Vol.2 No.-

The free cutting SDT61 steel is known as the materials of the standard hot work die with a good machinability which makes cutting after quenching possible, thereby, improving the machining accuracy and the effective productivity, compared with the conventional method of heat treatment after cutting. With SKD61 steel as the base metal, in varying additions of free cutting element S, non-metallic inclusion shape control elements Zr, Ca were added and melted in air and were casted, forged and heat treated finally to make specimens. The inclusion distribution was tested by etching pattern and image analyzer and composition and morphology of inclusions were examined with the optical and electron microscope. Therefore, the optimum size, distribution and phase of non-metallic inclusions were chosen to investigate the effects of addition elements on composition and morphology of inclusions in free machining STD61 steel and elucidate the mechanism of its formation. The results of this research were as followers. First, inclusion shape control elements Ca and effective Zr contributed in spheroidizing MnS, and Ca was especially effective in the fine distribution of inclusions. Sencond, in these steel types, the addition of Zr facilitated Zr nitride formation through nitride stabilizing elements such as Cr, Mo, V and Zr. The effective Zr exited as (Mn, Zr)S, thereby contributing in spherodizing MnS. Third, with increasing the additions of free cutting element S, the cleanness of steel was lowered due to the increase of MnS inclusions.