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Zr 합금의 석출물 및 부식특성에 미치는 Fe 와 Mn 첨가 영향
김현길,위명용,정용환,이명호,박상윤 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.11
In order to Investigate the effects of Fe and Mn on the precipitate and corrosion characteristics of Zr based alloys for nuclear fuel cladding, autoclave corrosion tests on the ternary(Zr-0.8Sn-X) alloys have been carried out at 360℃. The corrosion behavior of Zr-Sn-Fe alloy showed the cubic corrosion rate in the pre-transition region and the linear corrosion rate in the post-transition region. The good corrosion resistance in Zr-Sn-Fe alloy system was observed in Fe contents more than 0.2 wt%. The corrosion behavior of Zr-Sn-Mn alloy was significantly accelerated from the early stage. The lowest weight gain was observed in 0.2 wt% Mn. Based on the precipitate anallysis by TEM, it is thought that the corrosion of Zr-alloys would be related to the size of precipitate.
핵연료 피복관용 Zr 합금의 열처리에 다른 미세조직 및 부식특성
정용환,이명호,박상윤,김환철 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.12
The effects of final annealing temperature on microstructure and corrosion behavior of Zr-based alloys were investigated. Four kinds of Zr alleys were used for microstructural study and corrosion teat. Corrosion tests were carried out in static mini autoclave under 400℃ steam condition. Microstructures were analyzed by using TEM/EDS and image analyzer. The grain size and precipitate size of Zircaloy-4 increased with increasing the annealing temperature. As the annealing temperature increased, the corrosion resistance of Zircaloy-4 also increased due to the increase of precipitate size and grain size. Therefore, the precipitate size and grain size play an important role on the control of corrosion resistance of Zircaloy-4. However, it was considered from this study that the corrosion resistance of Nb-containing alloys would be controlled by the characteristics of beta phase rather than precipitate size.
다공질 박막을 이용한 FET 형 용존 산소 센서의 유속 의존성 개선
김영진,손병기,이영철,정훈 경북대학교 전자기술연구소 2001 電子技術硏究誌 Vol.22 No.2
FET type dissolved oxygen sensor was proposed to overcome the disadvantages of the amperometric Clark sensor. The inherent problem of the proposed sensor, however, is the flow dependence of the sensor performances since the proposed sensor detects the pH change in close proximity to the working electrode. In this study, a hydrodynamic porous thin film which can reduce the flow dependence were proposed the suggested porous thin film were formed onto sensing area and working electrode with mixed polymer matrix of TEOS and DEDMS.
핵연료 피복관용 Zircaloy-4 및 Zr-Nb 합금의 열처리에 따른 부식 및 기계적 특성 평가
김현길,정용환,이명호,윤영균 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.7
Effects of final annealing temperature on the corrosion and mechanical behavior, and microstructure were investigated for Zircaloy-4(Zr-1.3Sn-0.2Fe-0.1Cr), Alloy-1(Zr-0.4Nb-0.6Sn-0.4Fe-0.2Cu) and Alloy-2(Zr-1Nb). The corrosion tests were carried out in 360℃ water and 70 ppm LiOH solution in the static mini autoclaves. The mechanical tests were performed using the universal material test machine. The corrosion rate of Zircaloy-4 was not accelerated as the precipitates on Zircaloy-4 grew with the increase of annealing temperature after recrystallization. But the corrosion rate of Alloy-1 and 2 was accelerated due to the formation and growth of β-Zr phases with increasing the annealing temperature. Therefore, the corrosion resistance of the Zr-Nb alloy system could be improved by the control of heat treatment. It was also confirmed that the mechanical properties of Zr-based alloys were affected by the addition of alloying elements, the recrystallization, and the precipitation with annealing temperature.
간세포암과 주위 조직에서의 Transforming Growth Factor-beta 1과 그 수용체의 발현
최규완,백승운,최문석,김소정,이준혁,고광철,이풍렬,이종철,박상종,안병훈,김재준 대한소화기학회 2001 대한소화기학회지 Vol.37 No.4
Background/Aims: Transforming growth factor-beta 1 (TGF-β1) is a potent inhibitor of hepatocyte proliferation and its receptor is known to be involved in the carcinogenesis. This study was designed to compare the expression levels of the TGF-β1 and its receptor in neoplastic cells and its surrounding tissue and to assess their role in hepatic carcinogenesis. Methods: We measured the levels of TGF-β1 mRNA and TGF-β1 receptor II mRNA by semiquantitive RT-PCR for the tumor and its surrounding tissue of 30 patients with hepatocellular carcinoma (HCC). We analyzed the relationship between the expression of TGF-β1 mRNA, TGF-β1 receptor II mRNA and clinicopathological characteristics of HCC. Results: The expression of TGF-β1 mRNA showed no difference between HCC and its surrounding tissue, but the expression of TGF-β1 receptor II mRNA was lower in HCC than in its surrounding tissue (2.47±1.08 vs 3.53±1.50, p=0.00). There was no difference in the expression level of TGF-β1 mRNA and TGF-β1 receptor II mRNAo the clinicopathological characteristics of HCC. However, the ratio of TGF-β1 receptor II mRNA in HCC to that in surrounding tissue was more decreased in HCC with portal vein invasion (0.49±0.22 vs 0.77±0.21, p=0.01). Conclusions: Our data suggest that the loss of TGF-β1 receptor II may play an important role in carcinogenesis and tumor progression of HCC.
이미숙,손희정,강태욱,최규완,박동일,백승운,이준행,고광철,이종철,임윤정,이풍렬,김갑철,김재준 대한소화기내시경학회 2001 Clinical Endoscopy Vol.22 No.2
Background/Aims: Colonic ischemia is recognized as the most common vascular disorder of the intestines in the elderly. The severity of the disease may vary considerably with the prevalent benign transient forms, being amenable to conservative treatments and the severe gangrenous forms, requiring surgery. Correct diagnosis is usually made after the ischemic episode is over and colonic ischemia is frequently misdiagnosed. The aim of this study is to identify the clinical patterns and prognostic factors of ischemic colitis. Methods: We found 60 patients with nonoccusive ischemia of the large intestine, We analyzed age, sex, symptoms, signs, associated disease, location, endoscopy, hematologic, histologic, radiologic finding and treatment, retrospectively. Results: The mean age was 60.2±6.3 years. The most common symtoms were abdominal pain or bloody diarrhea. The most common sign was diffuse abdominal tenderness. The most common hematologic findings were anemia and leukocytosis. Associated medical illnesses wer diabetes, rhematoid arthritis and cerebrovascular accident, et al. Both computed tomography (CT) and endoscopy were useful diagnostic tools. The most common involved site was sigmoid colon. 46 patients were treated conservatively and 14 patients were managed surgically. Conclusions: Male gender, those with rebound tenderness, severe anemia, right or total colon involvement as well as rheumatoid arthritis had a poor prognosis. Both CT and endoscopy were useful in predicting prognosis.
니세틸 정(아세틸 - 엘 - 카르니틴 500mg)에 대한 뉴로세틸 정의 생물학적 동등성
조혜영,오인준,이용복,임동구,문재동,심영순,김은아,정현철 한국약제학회 2001 Journal of Pharmaceutical Investigation Vol.31 No.1
Acetyl-L-carnitine (ALC), an endogenous component of the L-carnitine family, is naturally occurring molecule synthesized from L-carnitine (LC) by carnitine acetyl transferase. ALC has been shown to improve the cognitive performance of patients suffering from dementia of the Alzheimer's type and proposed for treating Alzheimer's disease in pharmacological doses. The purpose of the present study was to evaluate the bioequivalence of two ALC tablets, Nicetile^(TM) (Dong-A pharmaceutical Co., Ltd.) and Neurocetil^(TM) (Kyung-Dong Pharmaceutical Co., Ltd.), according to the guidelines of Korea Food and Drug Administration. Twenty six normal male volunteers, 22.80±2.76 year in age and 63.07±7.98 ㎏ in body weight, were divided into two groups and a randomized 2 × 2 cross-over study was employed. After one tablet containing 500 ㎎ of ALC was orally administered, blood was taken at predetermined time intervals and the concentrations of ALC in serum were determined using HPLC with fluorescence detector. Because of the presence of endogenous ALC, the calibration was performed using dialyzed serum. Pharmacokinetic parameters such as AUC_t, C_(max) and T_(max) were calculated and ANOVA was utilized for the statistical analysis of the parameters. The results showed that the differences in AUC_t, C_(max) and T_(max) between two tablets were 2.72%, -0.65% and -8.42%, respectively, when calculated against the Nicetile^(TM) tablet. The powers (1-β) for AUC_t and C_(max) were 94.87% and 87.17%, respectively. Minimum detectable differences (△) at α=0.05 and 1-β=0.8 were less than 20% (e.g., 15.58% and 19.16% AUC_t and C_(max), respectively). The 90% confidence intervals were within ±20% (e.g., -11.84∼6.41 and -10.57∼11.88 for AUC_t and C_(max), respectively). Two parameters met the criteria of KFDA for bioequivalence, indicating that Neurocetil^(TM) tablet is bioequivalent to Nicetile^(TM) tablet.
김영호,장우영,이순진,손희정,최규완,도재혁,백승운,이준행,이풍렬,이종철,박철근,임윤정,김갑철,김재준,임효근 대한소화기학회 2001 대한소화기학회지 Vol.37 No.3
Background & Aims: Gastrointestinal stromal tumor (GIST) constitutes primary nonepithelial neoplasms of the gastrointestinal tract and includes most tumors previously designated as leiomyomas/leiomyosarcomas. GIST is pathologically divided into benign, borderline and malignanct tumor. This study was carried out to delineate the clinical and pathologic features of GIST and to establish the features predicting malignancy. Methods: Clinicopathologic data of 84 patients who had GIST from 1995 to 1999 were reviewed. Results: The subjects were 42 men and 42 women, and their mean age was 59.3±13.2 years. We located fifty-two tumors in the stomach, 28 tumors in the small intestine and 4 tumors in the colorectum years. Histopathology revealed benign tumors in 23 of the 84 patients, borderline tumors in 22, malignant tumors in 39. The average size of tumors was 6.23 cm in diameter (range, 0.6-26 cm). Metastasis was noted in 15.5% of the patients at diagnosis. On endoscopy, ulceration was more common in malignancy. Endsonographic findings except size were not significant statistically. On contrast enhanced computed tomography, malignancy showed more irregular shape and variable attenuation than benign lesions, which seemed to be valuable factor. Conclusions: The variables predicting malignancy were large tumor size (≥5 cm), location of the colorectum, palpable abdominal mass, ulceration on endoscopy, and less uniformity in shape and variable attenuation on computed tomography.