Al-Cu-Mg合金의 時效析出에 미치는 豫備時效의 影響

趙顯麒,洪俊杓,全在英 경북대학교 공과대학 1983 工大硏究誌 Vol.12 No.-

The influences of preageing on age-precipitation in Al-2.02t% Cu-1.1wt% Mg alloy have been investigated by means of measurements of hardness, tensile strength and electrical resistivity and transmission electron microscopy. The results obtained are summarized as follows. The two-step aged alloy is more age-hardenable than the onestep aged alloy in early stage of ageing. It is because of the formation and growth of solute atom cluster and GPB zones. The maximum hardness and strength of the alloy aged 200℃ is obtained by preaged at 100℃. It is because of fine and dense distribution of S'metastable phase. The hardness and strength are remarkably decreased with sufficient ageing time after preageing at room temperature and 170℃. It is because of the formation and coarsening of S'metastable phase by the preageing.

연쇄상구균을 실험감염시킨 넙치치어의 병리조직학적 관찰

조성환,류시윤,김현수,박배근,김덕환,손화영,윤원기,신창호 충남대학교 수의과대학 동물의과학연구소 1999 動物醫科學硏究誌 Vol.7 No.-

Pathological observations were examined after abdominal inoculation in 7∼8㎝ sized flounder (Paralichthys olivaceus) with 1X10^7 cfu/㎖ of Streptococcus faecalis. The infected flounder were clinically observed and weighed a fish body at 0, 5, 10, 15, 20, 25, 30 days post inoculation. In infected group, mortality were 70% and feed efficiency were 7.2%. In non-infected group, mortality were 10% and feed efficiency were 18.2%. Macroscopically, the significant lesions were characterized by protrusions and opacity of the eyes and ulcer of the caudal pecuncle. Histopathologically, the lesions were observed a degeneration. necrosis and inflammatory cells in muscle of the caudal peduncle and a degeneration and necrosis of the rod cells and detached retina from the black pigmented layer

Al-Mg-Si合金의 時效擧動에 미치는 加工熱處理의 影響

趙顯麒,李基大,朴定國 慶北大學校 1980 論文集 Vol.30 No.-

Effects of Thermo-Mechanical Treatment(TMT) on ageing behaviours in Al-Mg-Si alloy is investigated by means of tensile test, hardness measurements and transmission electron microscopy. The maximum 0.2% proof stress of the TMT materials in final ageing is higher by 10%∼20% than that of the two-step aged materials. The strength of TMT materials also increases more rapidly than that of two-step aged materials. The maximum 0.2% proof stress of the TMT materials with pre-ageing is higher than that of the TMT materials without pre-ageing. The strength of TMT materials increases with rising pre-ageing temperature, and it decreases with rising final-ageing temperature. Consequently, this type of TMT would have some practical significance in improving the mechanical properties of 6061 alloy.

다중 제어루프에 의한 자기부상용 DC-DC 전원장치에 관한 연구

조주현,조정민,전기영,이상집,이승환,오봉환,이훈구,한경희 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-

The author present a modified multi-loop algorithm including feedforward for controlling a 55kW step down chopper in the power supply of Maglev. The control law for the duty cycle consists of three terms. The first is the feedforward term which compensates for variations in the input voltage. The second term consists of the difference between the slowly moving inductor current and output current. The third term consists of proportional and integral terms involving the perturbation in the output voltage. This perturvation is derived by subtracting the desired output voltage from the actual output voltage. The proportional and integral action stabilizes the system and minimizes output voltage error. In order to verify the validity of the proposed multi-loop controller, simulation study was tried using Matlab simulink.

일방향 응고시킨 Al-Fe 2원 공정합금의 응고조직과 기계적성질에 미치는 Zr 첨가의영향

趙顯麒,林相元 慶北大學校 1989 論文集 Vol.47 No.-

Effects of Zr addition on structure and mechanical properties in unidirectionally solidifed Al-Fe eutectic alloy have been carried out by means of scanning electron micrography and the measurement of hardness and tensile strength. Especially, effects of Zr addition on ageing behaviours and precipitate distributions have been also conducted by the observation of transmission electron microscope. At first, by the addition of Zr, the eutectic fibre produced were very fine but, as the growth rate increase, the mechanical properties were somewhat deteriorated at room temperature by misalignment of fibre due to constitutional supersooling. On the other hand, Al_3Zr phases were precipitated in interface of matrix/fibre by the ageing at 365℃ for 50 hrs and these phase contributed to increase the mechanical properties remarkablely from RT to 500℃. This results deduced that the shear slip in interface was suppressed by Al_sZr precipitates which mitigated the difference of heat expansion coefficient between matrix and fibre.

Al-1.2%Mg_2Si擬二元系合金의 時效現象에 미치는 Cu添加의 影響

趙顯麒 慶北大學校 産業開發硏究所 1980 硏究報告 Vol.8 No.-

Effects of copper addition (up to 0.75%) on ageing phenomena in Al-1.2% Mg_2Si pseudo binary alloy were studied by means of hardness and electric resistivity measurements. The rate of age-hardening and the maximum hardness are increased by the Cu addition in the early stage of ageing at 175℃. Lowering of the hardness due to two-step ageing is relieved as the additional amount of Cu was increased, because Q' phase of a quaternary compound also precipitate in the alloys containing Cu adding to needle-like G.P. Zones.

Cu-Al-Ni 합금에 있어서 시효에 따른 감쇠능의 변화

조현기,박철규 경북대학교 산업기술연구소 1987 産業技術硏究誌 Vol.14 No.-

The effects of ageing on specific damping capacity in Cu-Al-Ni alloy were carried out by the torsional pendulum testing method with the computer system. The critical range of the reverse martensitic transformation was checked by measuring adiabatic scanning calorimeter and the microstructure was observed by the optical microscope. The extent of specific damping capacity in the region of the reverse martensitic transformation increases with the amount of matrix and martensitic interface. The peak of specific damping capacity appears when the amount of martensites becomes 50% The peak of specific damping capacity decreases according to ageing due to the stabilization of martensites and the decreasing rate of specific damping capacity increases. Specific damping capacity depends on the strain amplitude and non-elastic additional strain is hysteresis type. The high level of specific damping capacity found in Cu-Al-Ni alloy is most likely to due to the reversible movement of interfacial and twin boundaries on exposure to alternating stresses.

一方向凝固시킨 Al-Cu-Mg共晶合金의 機械的 性質에 미치는 時效의 影響

趙顯驥,康晃鎭,趙美子 慶北大學校 1982 論文集 Vol.33 No.-

The microstructure and mechanical properties of unidirectionally solidified Al-Cu-Mg eutectic alloys have been studied in as-grown and aged condition. After unidirectionally solidification, specimens of solution treated and quenched eutectic were at 180°, 230°, 260℃ in a salt bath for various time. The results obtained are as follows; 1) Precipitation on hardening of the ductile phase is a feasible mechanism for strengthening of composites. 2) Mechanical Testing of the tenary eutectic has shown that composite is strengthened about 30 to 50% by ageing. 3) Tensile and compression strength of this composites are 25 and 70kg/㎟ by ageing treatment in growth 0.1mm/min. 4) The unidirectionally solidified structure are changed by ageing. It seems that the low Cu and Mg solute atoms are likely due to epitaxial precipitation onto CuAl_2 lamellar respectively.

돼지생식기호흡기 증후군(PRRS) 바이러스 감염시킨 돼지 기관의 병리학적 관찰

조성환,김현수,윤원기,전무형,류시윤,박배근,손화영,김무강 충남대학교 수의과대학 동물의과학연구소 1996 動物醫科學硏究誌 Vol.4 No.-

The porcine reproductive and respiratory syndrome virus was inoculated into swine tracheal organ culture. The ballooning degeneration of the tracheal ciliated epithelium and a decrease of ciliary activity from the tracheal organs infected with PRRS virus were observed one day post-infection(PI). Tracheal epithelium showed degeneration and focal necrosis 2 days PI. Epithelial necrosis and loss of cilia and epithelial cells became more severe 3 and 4 days PI. An entire loss of cilia and epithelial cells were recognized 4 days PI, however, control tracheal organs were normal during the period of the experiment except a little decrease of ciliary activities with time..

면역학적 특성에 따른 yeast cytochrome c의 구조에 관한 연구

조경환,우기민,조만희,이상한,박현경,김창세 순천향의학연구소 2000 Journal of Soonchunhyang Medical Science Vol.6 No.2

The antiserum against yeast cytochrome c and horse heart cytochrome c was reacted immunologically with those from various species. The results were as followings; 1. The antiserum against horse heart cytochrome c was reacted immunologically with heart cytochrome c of horse, cow, rabbit, mouse, chicken, pigeon, frog, tuna, and guanaco, and were not with yeast and neurospora cytochrome c. 2. However, antiserum against yeast cytochrome c was only reacted immunologically with yeast cytochrome c, and was not mammals and vertebrates horse, cow, rabbit, mouse, chicken, pigeon, frog, tuna, guanaco, even neurospora 3. CNBr-digested peptides of horse heart cytochrome c were obtained 5 peaks, Ⅰ(1-80), Ⅱ(1-65), Ⅲ(66-104), Ⅳ(81-104), Ⅴ(66-80), and other peptide (1-50). Among them peptides Ⅰ and Ⅱ were weakly reacted immunologically with antiserum against horse heart cytochrome c. CNBr-digested peptides of horse heart cytochrome c were not reacted with antiserum against yeast cytochrome c. 4. From the above, the immunologically positive cross reaction was thought to be related with Ω loop D.