• Journal of the Korean Ceramic Society
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• v.37 no.9
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• pp.833-838
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• 2000

기존의 핵연료재료 습식처리 공정 대체를 위한 건식 처리 공정 기초 연구로서 산소 플라즈마 기체에 의한 금속우라늄과 이산화우라늄의 산화 연구를 수행하였다. 연구결과 산소 플라즈마를 사용할 경우 $UO_2$는 40$0^{\circ}C$에서 약 300% 정도, 50$0^{\circ}C$에서는 70% 정도의 산화율 증가가 일어났으며 금속우라늄의 경우에도 35$0^{\circ}C$에서 50% 정도의 증가를 확인할 수 있었다. 이들 산화율은 플라즈마 출력이 증가함에 따라 비례적으로 증가하였는데 이는 출력 증가에 따른 플라즈마내 산소 원자의 발생과 일치하여 이러한 산화율 증가 현상은 플라즈마내 산소 원자가 주도하는 것으로 드러났다. 이들 실험 결과는, 기존의 실험 결과와 길이, 시간에 따라 산화량이 선형적으로 증가하는 것으로 나타나 산소 플라즈마 산화 반응은 표면 반응이 주요 반응이라는 것이 밝혀졌다.

• Korean Journal of Clinical Pharmacy
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• v.9 no.2
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• pp.81-87
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• 1999

췌장이식의 성공률은 지난 10년 동안 상당히 상승되었다. International Pancreas Transplant Registry에 따르면 1995년 이래 미국에서만 매년 1,000건 이상의 췌장이식이 실시되고 있다. 장기이식후 나타나는 급성 거부반응은 이식 후 6개월 이내에 가장 높은 빈도수로 나타난다. 췌장이식환자에서는 신장을 이식한 것보다 두배나 높은 거부반응을 나타나며 이로 인한 입원율의 증가 항림프제(antilyinphocyte) 사용과 감염의 증가로 이환율이 높다. 더구나 Cyclosporine (CsA)을 기초로 한 면역억제제요법의 사용은 높은 급성 거부반응률(acute graft rejection)을 초래하여 이식한 장기의 조직손실이 문제가 되고 있다. 새로운 면역억제제인 Tacrolimus (FK506)의 사용은 이식환자에서의 거부반응을 감소시켜 생존율을 증가시키는 것으로 알려져 있다. Tacrolimus는 neutral macrolide로 cyclic peptide인 CsA과는 화학 구조는 매우 다르나 비슷한 면역억제 효과를 보인다. 하지만 Tacrolimus의 사용시 신경독성, 신독성, 특히 고혈당증의 발생률이 높아 일부 이식센터에서는 장기 이식 후에 사용하기를 꺼리기도 한다. 하지만 여러 연구논문에서 간과 신장 이식 후 급성 거부반응 예방에 Tacrolimus는 CsA에 비해 이점이 있는 결과를 발표하였다. 결과적으로, 현재 췌장이식 후 Tacrolimus를 기초로 한 면역억제의 효과에 대한 연구가 활발히 진행중이다. 따라서 본 연구에서는 1994-1996년 사이에 Tacrolimus 또는 CsA를 기초로 한 면역억제요법을 투여 받은 췌장이식환자 101명을 후향적으로 조사하여 Tacrolimus (n=54)와 CsA(n=57)의 급성 거부반응 예방 효과와 신부전 발생률을 비교하였다. 모든 환자는 항림프구 약물, Azathioprine, Prednisone을 이식 후 면역억제제로 투여 받았다 기준선으로부터 $20\%$ 이상의 혈청 creatinine의 상승이 있는 환자에서는 급성 신부전으로 정의하였고 신장생검법으로 거부반응을 진단하였다 Matched-pair analysis에 따르면 췌장이식환자의 6개월 생존율은 CsA군에서 $97\%$, Tacrolimus군에서 $96\%$로 별다른 차이가 없었으며 (p=0.57), 6개월간의 이식한 췌장의 보존율은 CsA군에서는 $88\%, Tacrolimus에서 $91\%$. 유의한 차이는 없었다(p=0.29). 췌장이식 후 6개월 동안 Tacrolimus의 사용은 생검으로 증명되는(biopsy-proven) 급성 거부반응의 발생빈도는 CsA보다 유의하게 낮았을 뿐만 아니라 (p<0.05) 거부반응 증상의 심각도 또한 감소시켰다 (p=0.03). 급성거부반응 발생빈도의 감소로 Tacrolimus군에서 antilymphocyte 치료가 유의하게 줄어들었다(p=0.01). CsA군에서 Tacrolimus보다 신부전의 발생률이 높았으나 통계학적 차이는 없었다. 췌장이식후의 최적의 면역억제요법의 결정하기 위해서는 향후 Tacrolimus와 CsA을 비교하는 전향적 무작위 연구가 필요하다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.997-1003
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• 2011

In order to investigate devolatilization characteristics for ashless coal with relatively low ash content and high heating value, an experiment was performed in different bed configurations of TGA and DTF(Drop Tube Furnace) at atmospheric pressure condition. The heating rate was $10^{\circ}C$/min up to $950^{\circ}C$ in TGA, while the temperatures of DTF varied from 500 to $1300^{\circ}C$ in step of $200^{\circ}C$. A weight loss and particle temperature were obtained to determine devolatilization kinetics. The kinetic parameters including an activation energy and pre-exponential factor for ashless coal were obtained using Coats-Redfern method in TGA and single step method in DTF. Furthermore, the devolatilization kinetics of the ashless coal were compared with the results of different kinds of conventional coal such as sub-bituminous and bituminous. The results show that the activation energy of devolatilazation for ashless coal is lower than those of others in fixed and entrained conditions.

• Geophysics and Geophysical Exploration
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• v.23 no.1
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• pp.55-60
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• 2020

The closed-form expressions of gravity, magnetic, gravity gradient tensor, and magnetic gradient tensor due to a rectangular prism are derived. The vertical gravity is derived via triple integration of a rectangular prism in Cartesian coordinates, and the two horizontal components of vector gravity are then derived via cycle permutation of the axis variables of vertical gravity through the axial symmetry of the rectangular prism. The gravity gradient tensor is obtained by differentiating the vector gravity with respect to each coordinate. Using Poisson's relation, a vector magnetic field with constant magnetic direction can be obtained from the gravity gradient tensor. Finally, the magnetic gradient tensor is derived by differentiating the vector magnetic with respect to appropriate coordinates.

• Korean journal of applied entomology
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• v.13 no.2 s.19
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• pp.77-82
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• 1974

The variety Tong-il from the IR667 lines have been reported as a variety resistant to the smaller brown planthopper, Laodelphax striatellus Fallen, in Korea. The resistance of Tong-il to the insect, however, have been mainly evaluated from a viewpoint of plant reaction of rice at the seedling stage. In this study, the nature of resistance of Tong-il to the insect was furthermore evaluated from the standpoints of feeding preference, antibiosis and plant tolerance in comparison with the resistant varieties Karsamba Red ASD-7 and Vellailangalayan. and the susceptible variety Jinheung which have been reported to the insect. The smaller brown planthopper much more prefered Tong-il for feeding than the resistant varieties ASD-7 and Vellailangalayan. The degree of antibiosis of Tong-il to the smaller brown planthopper was significantly lower than ASD-7 and Vellailangalayan. The results showed significantly lower nymphal mortality and higher adult emergence in Tong-il and Jinheung than other two resistant varieties. The degree o( tolerance of Tong-il to the insect was also lower than ASD-T and Vellailangalayan. Only. Tong-il seemed to be relatively more tolerable than Jinheung. The reason of showing resistant reaction of Tong-il in the mass screening test might be related with relatively lower feeding preference and more tolerance than Jinheung and other susceptible varieties.

• Journal of Life Science
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• v.14 no.2
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• pp.269-274
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• 2004

Using heterogeneous catalyst, esterification reaction of soybean oil (SBO) with methanol was investigated. Distributions of components in mixtures of soybean oil and methanol were measured at temperatures ranging from 40 to $65^{\circ}C$. Glycerine contents of reaction mixtures were measured for the different kinds of catalysts, such as NaOH, CaO, Ca(OH)$_2$, MgO, Mg(OH)$_2$, and Ba(OH)$_2$. Based on the measured glycerine concentrations, conversions of the reaction mixtures were calculated. The effects of dose of catalyst, cosolvent and reaction temperature on final conversion were examined. Solubility of methanol in soybean oil was substantially greater than that of soybean oil in methanol. When the esterification reaction of soybean oil was catalyzed by heterogeneous catalyst, final conversion was strongly dependent on the alkalinity of the heterogeneous catalyst, and increased with the alkalinity of the catalyst material. Hydroxides from the alkali metals were more effective than oxides, which actually had no catalytic effects. When Ca(OH)$_2$ was used for the esterification catalyst, maximum value of final conversion was measured at dose of 4%. The final conversion and reaction rate increased with reaction temperature, and showed substantial increment at reaction temperature of 5$0^{\circ}C$. When cosolvent, CHCl$_3$, was added into the reaction mixture of soybean oil which catalyzed by Ba(OH)$_2$, maximum value of final conversion was appeared at dose of 3%.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.133-140
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• 2014

The experiment was designed to compare the char combustion kinetics of pulverized Indonesia coals commonly utilized in Korea power plants. The reaction rate of coal char has been formulated using the external and internal effectiveness factors to describe the diffusion effect quantitatively. The Random Pore Model (RPM) was used for applying internal specific surface area as a function of carbon conversion ratio. Reaction rate was obtained from reaction time using the Wire Heating Reactor (WHR) which can heat and measure the char particle temperature at the same time. BET and TGA were used to obtain physical properties such as internal specific surface area and structural parameter. Three kinds of Indonesia Sub-bituminous coals "BARAMULTI, ENERGYMAN, AGM" were used in order to derive the activation energy and pre-exponential factor. The results of this study showed that the effect of internal diffusion than that of external diffusion is the dominant as comparison of kinetics was reflected in external and internal effectiveness factors. For three kinds of coal char, finally, activation energy of intrinsic kinetics indicates 110~118 kJ/mol.

• Solar Energy
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• v.12 no.3
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• pp.10-20
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• 1992

In this experiment, photochemical reaction has been applied to destroy TCE in water phase. The main target of this work is to investigate the technical feasibility of large scale of solar detoxification reactor for water treatment. The results have revealed that solar detoxification utilizing photon energy from the sun is the most attractive process to decompose organic toxins in water phase at room temperature. The detailed results from this work are as follows; (1) The highest conversion ratio of TCE was obtained by using $TiO_2$, annatase as a photocatalyst among $TiO_2$ anatase, $TiO_2$ rutile and $V_2O_5$ under the same experimental condition. The anatase crystal structure was confirmed with XRD analysis, and its surface area was 7.748 $m^2/g$ from the BET-$N_2$ measurement (2) 0.1 wt% of $TiO_2$ anatase has been adopted as optimal quantity for batch slurry reactor at this experimental conditions. (3) The effect of hydrogen peroxide on the conversion of TCE was investigated. Its optimal quantity was 0.06 vol. % under this experimental conditions. (4) The effect of oxygen on the conversion of TCE also was studied by controlling the head space in photoreactor. Results indicated that sufficient amount of oxygen should be supplied to accomplish the highest conversion rate of TCE in water phase.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.876-888
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• 2021

Purpose The aim of this study was to compare the diameter and volume of liver metastases on CT images in relation to overall survival and tumor response in patients with gastric cancer liver metastases (GCLM) treated with chemotherapy. Materials and Methods We recruited 43 patients with GCLM who underwent chemotherapy as a first-line treatment. We performed a three-dimensional quantification of the metastases for each patient. An independent survival analysis using the Response Evaluation Criteria in Solid Tumors (RECIST) was performed and compared to volumetric measurements. Overall survival was evaluated using Kaplan-Meier analysis and compared using Cox proportional hazard ratios following univariate analyses. Results When patients were classified as responders or non-responders based on volumetric criteria, the median overall survival was 23.6 months [95% confidence interval (CI), 8.63-38.57] and 7.6 months (95% CI, 3.78-11.42), respectively (p = 0.039). The volumetric analysis and RECIST of the non-progressing and progressing groups showed similar results based on the Kaplan-Meier method (p = 0.006) and the Cox proportional hazard model (p = 0.008). Conclusion Volumetric assessment of liver metastases could be an alternative predictor of overall survival for patients with GCLM treated with chemotherapy.

• Tuberculosis and Respiratory Diseases
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• v.53 no.4
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• pp.389-400
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• 2002

Background : The rapid diagnostic tests for tuberculosis are needed to facilitate early treatment of tuberculosis and prevention of Mycobacterium tuberculosis transmission. The Xeniss Rapid TB kit is a rapid, card-based immunochromatographic test for the detection of antibodies directed against M. tuberculosis antigens including antigen 5(38-kDa antigen). The objective of this study was to evaluate the performance of the Xeniss Rapid TB kit for the diagnosis of active tuberculosis with serums from patients, asymptomatic healthy and close contact controls. Methods : 188 patients with active tuberculosis were tested; 177 with pulmonary tuberculosis(18 with combined pleurisy), and 11 with extrapulmonary tuberculosis. The control groups were composed of 82 close contacts and 57 healthy adults. Study subject were drawn from one national tuberculosis hospital for patients and close contacts, and another private hospital for healthy adults in Masan city, Korea. The Xeniss Rapid TB kit(Xeniss Life Science Co., Ltd., Seoul, Korea) was evaluated by using serum samples according to the instructions of the manufacturer by an investigator masked to the clinical and microbiological status of the study subjects. Results : The diagnostic sensitivity of the Xeniss Rapid TB kit was 73.9% in patients and specificities were 73.2% and 93.0% in close contact and healthy adults respectively. The positive predictive value in patients was 84.2% and the negative predictive value in controls was 85.8%. Conclusion : This study shows that the Xeniss Rapid TB test is a simple and fast method to diagnose active TB. The results of the sensitivity and specificites suggest that serodiagnosis using this point of care testing(POCT) device would be valuable and advantageous for screening tuberculosis in the clinical field.