크롬-망간鋼에서 析出된 複合炭化物의 粗大化 特性에 관한 硏究

崔鎭源,李相允,安哲佑 東亞大學校 大學院 1987 大學院論文集 Vol.12 No.-

This study has been carried out to investigate into the Ostwald Ripening behaviors of comples carbide particles precipitated in Cr-Mn steel during spheroidizing treatment at a range of temperature 650℃ to 710℃ after standarding the initial particle size distribution. The results obtained from the experiment are as follows; 1. Optical micrographs have shown that the precipitated particles mostly grow along grain boundaries with their shapes being irregular and that particles within the ferrite matrix appear to be small spheres. 2. Average particle size measurements have presented that a reciprocal of the slopes of three straight lines obtained from the relation between the log of average particle radius and the log of spheroidiaing time for 650℃, 680℃ and 710℃ approaches a value of 3.5 and that the growth of complex carbide particles occurs by a diffusion controlled mechanism combined with volume diffusion and grain boundary diffusion. 3. In has been found from the measured values for the average particle radius and the number of particles per unit volume that the average value of activation energy is 48.3Kcal/mole, which shows that the coarsening of complex carbide particles is governed by the interdiffusion mechanism of Fe, C, Cr and Mn atoms. 4. X-ray diffraction analysis has shown that the complex carbide particles precipitated during spheroidizing treatment are of two types, (Fe, Cr, Mn)₃C and (Fe, Cr, Mn)? C₃. 5. Experimentally measured particle size distribution curves approach the steady state distribution curve obtained for volume diffusion but their width and height are relatively broader and lower.

단기간 근권 저온처리가 수경재배 상추의 질산태 질소 함량에 미치는 영향

최승주,양진철,사동민 한국환경농학회 2002 한국환경농학회지 Vol.21 No.1

질산태 질소의 일중 농도 변화와 단기간의 저온 처리가 질산태 질소의 흡수 및 농도에 미치는 영향을 살펴보고자 상추(Lactuca sativa L.)를 공시 작물로 하여 온실에서 수경 재배하였다. 질산태 질소의 농도는 염산에 비하여 주맥에서 일중 지속적으로 2배 이상 높았으며, 질산태 질소의 일중 변화는 14:00까지 지속적으로 감소하여 최저치 (8.7 mg-N/GDW)를 나타낸 후 다시 증가하였다. 질산태 질소의 일중 흡수량은 11:00~17:00에 평균 4.8mg-N/GDW-Root/hr로 최대치를 나타내었다. 단기간의 저온 처리량을 50%~55%를 감소시켰다. 이러한 결과는 수확 전 단기간의 저온처리가 상추 잎의 질산태 질소함량을 낮출 수 있는 방법으로 응용될 수 있음을 보여준다. Lettuce (Lactuca sativa L.) plants were grown under hydroponic system to characterize the diurnal change of nitrate concentration and nitrate uptake rate and to examine the effect of short term cold treatment to rhizosphere on nitrate concentration and uptake rate in lettuce plant. The nitrate concentrations in midrib were two times higher than those in leaf. Nitrate concentration in the shoot reached to minimum (8.7 mg-N/GDW) at 14:00 and, thereafter, increased continuously until 23:00. During 11:00~17:00, nitrate uptake by lettuce plant was maximum (4.8 mg-N/GDW-Root/hr). Short term cold treatment reduced nitrate concentration in the shoot by 14~18%, and nitrate uptake rate by 50~55%, respectively. These results showed that short term cold treatment before harvest could be applied for the purpose of reduction of nitrate concentration in the leaf under hydroponic culture.

백서에서 실험적 치아이동시 치조골 흡수에 미치는 Bisphosphonate의 영향 : 생화학적 및 조직학적 관찰 Biochemical & Histological Observations

최진휴,김종철 대한치과교정학회 1999 대한치과교정학회지 Vol.29 No.1

백서에서 실험적 치아 이동시 bisphosphonate가 파골세포의 형성에 미치는 영향과 골 흡수 억제기전을 규명하고 독성유무를 알아보고자 하였다. 체중 260-350g의 웅성 백서 87마리를 정상군(장치비장착 + 0.9% NaCl), 대조군(장치장착 _ 0.9% NaCl) 및 장치장착후 bisphosphonate 투여군(0.8mg, 4 mg, 20 mg, 및 100mg/kg) 으로 분류하였다. 상악 좌측 제1대구치를 근심으로 치아이동이 일어나도록 50-70g의 교정력을 가하고, 교정장치 장착후 1일, 3일 및 7일째에 혈청 acid phosphatase와 lactate dehydrogenase (LDH)의 활성도를 측정하고, 또한 제1대구치를 포함한 상악골일부에서 파골세포수 및 골흡수 정도를 조직학적으로 관찰하여 다음과 같은 성적을 얻었다. 1. Acid phosphatase 활성도는 장치후 1일째와 3일째에 대조군과 bisphosphonate 투여군에 서 모두 정상군에 비해 2-3배 높았으나, 7일째에는 정상군과 유의한 차이를 보이지 않았다. 2. LDH활성도는 bisphosphonate 4 mg과 20mg/kg 투여군에서 전 실험기간에 걸쳐 증가된 양상을 보였으나 0.8mg과 100mg/kg 투여군에서는 유의한 차이를 나타내지 않았다. 3. 골흡수는 장치후 1일째에 대조군과 bisphosphonate 투여군에서 모두 관찰되지 않았으나, 3일 이후에 나타난 7일째가지 지속되었다. Bisphosphonate 4, 20 및 100mg/kg 군에서의 골흡수정도는 3일째에는 대조군에 비해 미약하였으나 7일째에는 대조군과 유사하게 나타났다. 4. 파골세포는 1일째에 대조군이나 bisphosphonate 투여군 모두에서 거의 관찰할 수 없었다. 3일째에 대조군에서는 파골세포가 다량 출현하였으나 bisphosphonate 투여군에서는 약물의 용량이 증가함에 따라 감소하여 나타났다. 이상의 결과로 실험적 치아이동시 파골세포의 형성억제가 bisphosphonate에 의한 골흡수억제기전이 아님을 알 수 있었고, bisphosphonate는 투여량이 증가에 따른 뚜렷한 세포독성은 관찰되지 않았으며, 골흡수 억제효과를 지속시키기 위해서는 약물이 반복적으로 투여되어야 할 필요가 있음이 시사되었다. This study was performed to examine the effect of bisphosphonate, an inhibitor of bone resorption, on the formation of osteoclast and bone resorption during experimental tooth movement. Whether bisphosphonate has a cytotoxity in high dose was also examined. Eighty-seven male Sprague-Dawley rats, weighing 260-350g, were classified into normal (no appliance + 0.9% NaCl), control (appliance + 0.9% NaCl) and four bisphosphonate-treated (appliance + 0.8, 4, 20, or 100mg/kg) groups. The maxillary left first molar was moved mesially with the tipping movement using 5-70g of force. Bisphosphonate(etidronate disodium) was injected intraperitoneally with a dose of 0.8, 4, 20 or 100mg/kg simultaneously with the application of the orthodontic force. They were killed at day 1, 3 or 7 after the application of the orthodontic force. The activities of serum acid phosphatase and lactate dehydrogenase (LDH) were assayed, and osteoclasts and the degree of bone resorption were examined histologically. The results obtained were as follows: 1. Acid phosphatase activities were significantly higher in the appliance groups, both control and bisphosphonate-treated (4, 20, and 100 mg/kg) groups, at days 1 and 3 than these in normal. At day 1, bisphosphonate-treated(4, 20mg/kg) groups showed even higher acid phosphatase than control. However, at day 7, no significant difference was noted between the control and bisphosphonate-treated groups. 2. LDH activities in the 4, 20mg/kg bisphosphonate-treated groups were increased during the experimental periods examined, but there were no significant differences in the 0.8, 100mg/kg bisphosphonate-treated groups. 3. There was no bone resorption at day, 1, but severe bone resorption was observed at days 3 and 7 in the control. Bone resorption was reduced by bisphosphonate-treatment at day 3. Bone resorption observed at day 7 was similar between the control and bisphosphonate-treated groups. 4. Few osteoclasts were observed at the alveolar bone in the control and bisphosphonate-treated groups at day 1. At day 3, numerous osteoclasts were shown in the control, the degree of which was reduced in bisphosphonate-treated groups. These results suggest that the inhibition of the osteoclast formation was not the mechanism of bone resorption by the bisphosphonate-treatment during experimenal tooth movement. There was no distinct cytotoxicity with a high dose of bisphosphonate. And the drug should be administrated repeatedly to maintain the inhibitory effect of bone resorption.

방사선조사가 설의 개방성창상치유에서 섬유아세포의 재형성에 미치는 영향에 관한 연구

최순철,박태원,유동수,이진구 大韓口腔顎顔面 放射線學會 1997 Imaging Science in Dentistry Vol.27 No.1

Radiation-impaired wound healing in animal experiments was believed to be an another logical experimental model to understand the wound healing mechanism in patients. The purpose of this study was to reveal the block point which would result in impaired healing. Twenty four rats(Sprague-Dawley strains) were divided into two groups according to the time interval between irradiation and wounding. Group I, observing the healing effect on the lst day and GroupⅡ are the healing effects on the 7th days after irradiation to the wound of the rat tongue. Experimental animals were sacrificed 3, 6, 12, and 24 hours after wounding. The specimens were examined by the light microscope and transmission electron microscope. The following results were obtained 1. Fibroblasts in both groups showed degenerative changes which were dilated mitochondria and rER, reduced microorganelle, vacuoles and little cytoplasmic process. 2. Average length between bands and quantity of the newly produced collagen fibers around fibroblasts remained unchanged against control group. 3. The severity of degenerative change of the fibroblast and impairment of wound healing including shortening of the thickness of collagen fibers were more severe in the group Ⅱ than in the group I.

팥의 RAPD 분석 조건 최적화 연구

이충열,박현철,박진철,김성만,김용철,최재희,최인수 밀양대학교 농업기술개발연구소 2000 農業技術開發硏究所報 Vol.4 No.1

The object of this study was to optimize PCR condition for RAPD analysis in adzuki bean. The best template DNA concentration was 20ng(0.25unit taq polymerase and 2.5mM MgCl2), 40ng(1unit taq polymerase and 2.5mM MgCl2, 1unit taq polymerase and 4.5mM MgCl2 and lunit taq polymerase and 7.0mM MgCl2), and 60ng(0.5unit taq polymerase and 2.5mM MgCl2, 0.5unit taq polymerase and 4.5mM MgCl2, 1unit taq polymerase and 2.5mM MgCl2, and 1unit taq polymerase and 4.5mM MgCl2) The best MgCl2 concentration was 2.5mM(40ng template DNA and 1unit taq polymerase, 60ng template DNA and 0.5unit taq polymerase, and 60ng template DNA and 1unit taq polymerase), 4.5mM(20ng template DNA and 0.25unit taq polymerase, 60ng template DNA and 0.5unit taq polymerase, and 60ng template DNA and 1unit taq polymerase), and 7.0mM(40ng template DNA and 1unit taq polymerase). Amount of taq polymerase was 0.25unit(20ng template DNA and 2.5mM MgCl2), 0.5unit(60ng template DNA and 2.5mM MgCl2, 60ng template DNA and 4.5mM MgCl2) and 1unit(40ng template DNA and 2.5mM MgCl2, 40ng template DNA and 4.5mM MgCl2, 40ng template DNA and 7.0mM MgCl2, 60ng template DNA and 2.5mM MgCl2, 60ng template DNA and 4.5mM MgCl2, and 60ng template DNA and 7.0mM MgCl2). When we consider results from template DNA concentration, MgCl2 concentration, and amount of taq polymerase, the best condition for PCR optimization was 60ng template DNA, 4.5mM MgCl2, and 1unit taq polymerase. Reaction temperatures for the optimal PCR condition were 84℃, 32℃, 62℃; 90℃, 40℃, 72℃; and 92℃, 36℃, 72℃.

회야강(울산)의 식물플랑크톤 군집구조

최철만,배진현 한국환경과학회 2002 한국환경과학회지 Vol.11 No.3

This study was conducted to find the structure of phytoplankton community in the Hoeya river(Ulsan) from March 2000 to February 2001. The taxa of phytoplankton identified included 135 species, 5 divisions, 33 families and 82 genera. Among them, chrysophyta(diatoms) were 63 species(46.7%), chlorophyta(green algae) 47 species(34.8%), pyrrophyta(dinoflagellates) 13 species(9.6%), cyanophyta (cyanobacteria) 8 species(5.9%) and euglenophyta(euglenoids) 4 species(3.0%) respectively. Ecological important species is called frequently appearing species, red tide causative species, seawater species and pollution indicator. 22 species including Aulacoseira granulata were recorded frequently appearing species. 19 species including Ceratium furca were recorded as red tide causing species. And the pollution indicators were 33 species including Actinastrum hantzschil var. fluviatile. The highest standing crops were 3,103,441 cell/ℓ in August at the RW-1 and the lowest 1,245 cell/ℓ in January at the RW-5. In the community analysis, the dominanance indices ranged from 0.34(October, RW-2) to 0.94(January, RW-1) and the diversity indices from 0.50(May, RW-2) to 2.57(September, RW-2). The saprobic indices were 2.43 in RW-1, 2.41in RW-2, 2.375 in RW-3, 2.40 in RW-4, 2.43, in RW-5. Therefore, these areas were investigated "β-mesosaprobic". According to the similarity index among the stations, these areas were defined as residential district areas(RW-2 and RW-3), lower part of the dam (RW-1) and seawater areas(RW-4 and RW-5).

Ciprofloxacin 제제의 생물학적 동등성에 관한 연구

최철희,신재국,신완균,유호진,이경훈,정원석,장인진,신상구 대한화학요법학회 1991 대한화학요법학회지 Vol.9 No.1

국내 시판중인 ciprofloxacin 제제인 Citopcin®(250㎎ tablet)의 동등성을 검토하기 위해 제조원인 Bayer사의 Citopcin®(250㎎ tablet)를 기준제제로 하여 18명의 건강한 남성 피험자를 대상으로 500㎎ 1회 교차 경구 투여후 약동학적 성상을 분석비교한 결과는 다음과 같다. 시험제제의 생체 이용율의 지표인 AUC, C_(mao), T_(max) 및 MRT들의 평균치는 백분율차이에 있어 모든 기준제제 지표의 ± 20% 이내였으며, 이들 생체 이용율 지표들은 분산분석 검정에서 차이를 인지할 수 없었다.생체 이용율 지표들의 기준제제에 대한 백분율 90% 대칭 신뢰구간 검토시 모든 경수들에서 ± 20% 이내의 조건을 만족하였으며 AUC의 경우에는 대칭형 신뢰구간으로 변환시 95% 신뢰구간에서도 동등성의 조건을 만족하였다, 이상의 시험결과로 시험제제인 Citopcin®은 기준제제인 Ciprobay®와 생물학적 동등한 제제로 판단되었다. The pharmacokinetics of ciprofloxacin was studied for the evaluation of the bioequivalence of the generic ciproflocacin products. Two single doses of 500㎎ each of ciprofloxacin(Ciprobay® 250㎎ tablet as a reference compound and Citopcin® 250㎎ tablet s a test compound) were administered orally to ighteen male volunteers in a balanced, randomized crossover design. Pek plasma levels of ciprofloxacin were observed about 1 hour after the doses and the peak concentrations of both products were similar(Ciprobay®, 3.18㎍/㎖; Citopcin®, 2.89㎍/㎖). The values of other pharmacokinetic parameter of ciprofloxacin computed for Ciprobay® are presented in that order: AUC=13.53:12.47㎍·h/㎖, T_(max)=1.28:1.14 hours; MRT=5.30:5.08 hours; t_(1/2)β=3.65:3.47 hours. No satistically significant, differences were detected when AUC and the other parameters were compared with the method of ANOVA. Using the criteria of 90% confidence interval for the assessment of bioequivalence al the parameters were acceptable. The products were found to be equivalent on the premise that no significant difference was detected when the relevant pharmacokinetic parameters were compared, and the confidence limit analysis showed acceptable results.

조명광원의 색온도와 조도 및 스펙트럼 측정

최대욱,박성진,임춘우,석성수,오철한 慶北大學校 師範大學 科學敎育硏究所 1999 科學敎育硏究誌 Vol.23 No.-

The peak wavelength and temperatures of W-Halogen standard light source were measured by using the modified Wien's Law. In the case of graybody, the emissivity ε should be taken into account in using the Wien's Law. In the experiment, PDA spectroscope was used for the measurement of peak wavelength of intensity distribution of spectrum. As the current of light source increases from 5A to 7.4A, the peak wavelength of intensity distribution of the spectrum decreased from 717nm to 690nm, and temperature increased from 3127K to 3330K. Illuminations of three-wavelength lamps and light source were also measured. It was found that irradiation spectrum of those three-wavelength lamps are not coincident to blue(450nm), green(550nm) and red(610nm).

백서에서 실험적 치아이동시 치조골 흡수에 미치는 Bisphosphonate의 영향 : Biochemical & Histological Observations

최진휴,김종철 전남대학교 치과대학 1998 전남치대논문집 Vol.10 No.1

This study was performed to examine the effect of bisphosphonate, an inhibitor of bone resorption, on the formation of osteoclast and bone resorption during experimental tooth movement. Whether bisphosphonate has a cytotoxicity in high dose was also examined. Eighty-seven male Sprague-Dawley rats, weighing 260-350g, were classified into normal (no appliance + 0.9% NaCl), control (appliance + 0.9% NaCl) and four bisphosphonate-treated (appliance + 0.8, 4, 20 or 100 ㎎/㎏) groups. The maxillary left first molar was moved mesially with the tipping movement using 50-70g of force. Bisphosphonate(etidronate disodium) was injected intraperitoneally with a dose of 0.8, 4, 20, or 100 ㎎/㎏ simultaneously with the application of the orthodontic force. They were killed at day 1, 3, or 7 after the application of the orthodontic force. The activities of serum acid phosphatase and lactate dehydrogenase (LDH) were assayed, and osteoclasts and the degree of bone resorption were examined histologically. The results obtained were as follows: 1. Acid phosphatase activities were significantly higher in the appliance groups, both control and bisphosphonate-treated (4, 20, and 100 ㎎/㎏) groups, at day 1 and 3 than these in normal. At day 1, bisphosphonate-treated(4, 20㎎/㎏) groups showed even higher acid phosphatase than control. However, at day 7, no significant difference was noted between the control and bisphosphonate-treated groups. 2. LDH activities in the 4, 20㎎/㎏ bisphosphonate-treated groups were increased during the experimental periods examined, but there were no significant differences in the 0.8, 100㎎/㎏ bisphosphonate-treated groups. 3. There was no bone resorption at day 1, but severe bone resorption was observed at days 3 and 7 in the control. Bone resorption was reduced by bisphosphonate-treatment at day 3. Bone resorption observed at day 7 was similat between the control and bisphosphonate-treated groups. 4. Few osteoclasts were observed at the alveolar bone in the control and bisphosphonate-treated groups at day1. At day 3, numerous osteoclasts were shown in the control, the degree of which was reduced in bisphophonate-treated groups. These results suggest that the inhibition of the osteoclast formation was not the mechanism of bone resorption by the bisphosphonate-treated during experimental tooth movement. There was no distinct cytotoxicity with a high dose of bisphosphonate. And the drug should be administrated repeatedly to maintain the inhibitory effect of bone resorption.

Molar Uprighting Spring에 의해 발생되는 치조골내의 응력분포에 관한 광탄성학적 연구

최진휴,김종철 전남대학교 치과대학 1990 전남치대논문집 Vol.2 No.1

This study was performed to analyze the effects of forces to the alveolar bone by various molar uprighting spring such as helical uprighting spring, T-loop spring, Modified T-loop spring and open coil spring. The simplified two-dimensional photoelastic model was constructed with a lower left posterior quadrant containing the second molar, the first and second premolars and the canine, with the first molar missing. Several molar uprighting springs were fabricated from 0.017 by 0.022 inch blue Elgiloy and applied to the photoelastic model. Two-dimensional photoelastic stress analysis was performed, and the stress distribution was recorded by photography. The results obtained were as follows ; 1. In all the kinds of the springs, the center of rotation of the mandibular second molar was observed at the apical 1/5-1/6 between the alveolar crest and the root apex. 2. In all the kinds of the spring, the stress induced in the mesial root surface of the manibular second molar was relatively homogeneous but there was some difference in the magnitude of the stress. 3. In the kinds of the springs, the distal crown tipping moment of the second molar was increased in turn as open coil spring, helical uprighting spring, T-loop spring, and modified T-loop spring. 4. The largest extrusive force was occured in the T-loop spring, intrusive force was occured in Modified T-loop spring only, and the largest distal tipping force was occured in open coil spring. 5. In the T-loop spring with activation, the stress induced in the mesial root surface of the second molar was increased gradually from the root apex to the alveolar crest and highly concentrated in the alveolar crest.