• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.252-252
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• 2021

하천 합류부의 흐름거동은 단일 하천 흐름거동에 비해 복잡한 흐름 특성을 나타낸다. 하천의 본류와 지류가 만나는 합류지점에서는 유량비, 합류각의 변화에 따라 전단면(shear plane), 재순환류(recirculation zone)가 발생할 수 있다. 이러한 하천 합류부의 복잡한 흐름특성은 하상의 침식 또는 퇴적을 야기할 수 있고, 수심의 변화, 수생태 변화 등을 일으켜, 하천환경 변화에 영향을 미칠 수 있다. 따라서 본 연구에서는 2차원 흐름해석모형 HDM-2D를 이용하여 하천합류부에서 2차원 흐름 모의를 수행하였으며, 합류각의 변화에 따른 흐름특성 변화를 분석했다. HDM-2D 흐름모의 결과의 검증을 위해 90° 각도의 합류수로에 대한 Weber et al.(2001)의 실험결과를 이용했다. 그 결과, 합류지점 하류에서 발생하는 재순환류 및 수위하강, 유속의 변화 등의 수치모의결과가 실험결과와 유사한 변화를 나타냈다. 지류 합류 각도의 변화에 따른 하류 흐름변화를 비교하기 위해 3가지 합류부 각도(30°, 45°, 60°)에 대해 흐름모의를 수행했다. 합류지점의 흐름특성을 분석하기 위해 합류지점의 계산격자를 세밀하게 구성했다. 합류지점 하류에서 발생하는 재순환류의 길이와 최대 폭의 변화로부터 재순환류 발생면적을 계산하였으며, 합류각도의 변화에 따른 흐름특성을 비교 분석 하였다. 흐름모의 결과, 본류와 지류의 합류각이 30°일 때 합류부 내측의 재순환류가 거의 발생하지 않았으며, 합류각이 45°이상일 때 합류각 증가에 따라 재순환류의 폭과 너비가 증가하는 결과를 나타냈다. 또한 합류각 증가에 의해 재순환류 발생 면적이 증가함에 따라 합류부 하류의 수심이 더 큰 폭으로 감소하는 결과를 나타냈다.

• Plant Journal
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• v.13 no.3
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• pp.26-29
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• 2017

In this research, the composition of the feed stream is optimized in pressure swing distillation for separating of methanol-acetone. It is well known that the composition of feed stream in pressure swing distillation system has a great influence on the feasibility to separate mixture. The workscope of this study is to show better separation efficiency at specified pressure by controlling the composition of feed stream with recycle of two products. Based on the base case without recycle flow, two processes are designed that methanol and acetone are recycled to feed stream, respectively. Each processes are compared with total annual cost and as a result, the base case without recycle flow are most favorable.

• Journal of Digital Convergence
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• v.15 no.11
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• pp.221-229
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• 2017

The purpose of this study is to find out ways to enhance corporate value by using more efficient use of non-reflux Income which is commonly considered in existing corporate income tax refund and newly introduced investment and mutual aid promotion tax. Specifically, we analyzed the effect of income tax return income and income tax return on wages and fixed - asset investments, which are commonly considered in the two tax systems, on firm value. As a result of the analysis, it was confirmed that short-term internal reserves and income reflux activities had a negative impact on firm value, and long-term internal reserves and income reflux return had positive effects on firm value. It is recommended not to formulate uniform criteria such as the ratio of income refund activity to the contents of tax, but to apply the tax refund to the internal taxation system and the taxable income source.

• Journal of Chest Surgery
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• v.30 no.5
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• pp.493-500
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• 1997

We performed this study to evaluate hepatic venous drainage in atrial isomerism by MR and the clinical significance of anomalous hepatic venous return in total cavopulmonary shunt operation. Numbers and locations of hepatic veins in twenty-two patients with isomerism(thirteen with right isomerism and nine with left isom rism) were evaluated by MR. Operative procedure of hepatic veins and postoperative arterial oxygen saturation were compared with hepatic vein connection in six patients after total cavopulmonary shunt operation. Among nine patients with left isomerism, hepatic venous return was totally anomalous via a single opening in eight, and via two separate openings in one. Among thirteen patients with right isomerism, partial anomalous hepatic venous connection directly to the atrium was seen in four. One showed total anomalous hepatic venous connection to atrium through one opening. Total cavopulmonary shunt operation was performed in 6 patients. Hepatic veins were connected to pulmonary arteries in four patients who had one atrial opening of hepatic vein andlor IVC, or two ipsilateral atrial opening of hepatic veins and IVC. In conclusion, hepatic vein drainage to atrium is variable in atrial isomerism. MR is useful for evaluation of hepatic vein drainage in atrial isomerism and surgical pla ning.

• Applied Biological Chemistry
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• v.37 no.1
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• pp.9-13
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• 1994

Baikhaju, the traditional Korean rice wine was brewed and distilled at various conditions-at different pressure (760, 460, 260 mmHg), different reflux ratio (3.1 : 1, 1 : 1) and different column conditions (packed and unpacked), and distillation operation was investigated. The sample wine, Baikhaju showed alcohol content of 14.2%, acidity 8.3 (g/100 ml), ethyl acetate 49 ppm, fusel oil 657 ppm. As the distillation was proceeded, alcohol concentration of distillate was decreased and that was higher in atmospheric pressure rather than reduced pressure. When the pressure was increased, the slope showed the relation of alcohol concentration between still liquid and vapour was increased, and also as the reflux ratio was increased, alcohol concentration of distillate was increased, and that was 0.56 mole at the reflux ratio 3.1 : 1 at atmospheric pressure, where 0.54 mole at 1 : 1 reflux ratio. As the distillation was proceeded, the rate of distillation was decreased, and that was higher values in the reduced pressure than atmospheric pressure. The maximum value (0.14 ml/s) of rate of distillation was observed in the packed column at 260 mmHg. As the reflux ratio was increased, the rate of distillation was decreased, and that was 0.05 ml/sec at reflux ratio 3.1 : 1 at atmospheric pressure, where 0.06 ml/sec at 1 : 1 reflux ratio.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.182-184
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• 2023

본 논문에서는 안전한국훈련의 체계적은 포괄적 훈련 프로세스 모델을 개발하기 위해 국제표준인 ISO 22398과 미국의 국토안보훈련(Homeland Security Exercise and Evaluation Program, HSEEP)의 훈련 모델에 기반해 국내 안전훈련을 위한 훈련 모델을 개발하였다. ISO 22398에서는 훈련 프로그램, 훈련 프로젝트, 그리고 지속적 개선을 통한 환류 구조를 제시하고 있었고, 미국의 국토안보훈련에서는 대비 순환과 훈련 순환 구조를 서로 엮는 것으로 포괄적인 훈련 환류 구조를 완성하였다. 한국의 안전훈련이 연속성을 가지기 위해서는 두 훈련 모델을 통합해 지속적으로 환류지속이 가능한 훈련 모델의 개발이 필요해 이를 제시하였다.

• Journal of the Korea Society for Simulation
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• v.5 no.1
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• pp.43-50
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• 1996

2-propanol/acetone/hydrogen 반응계로 구성된 화학적 열펌프 시스템은 낮은 온도(82.5~$90^{\circ}C$)에서의 2-propanol의 탈수소화 반응과 높은 온도(약 $200^{\circ}C$ 부근)에서의 acetone의 수소화반응을 이용하여 열을 고품위화 시키는 장치이다. 본 연구에서는 이 시스템의 해석 및 설계를 목적으로 이 시스템에 대한 수치적인 모델들을 세우고 Sequential modular approach를 이용하여 시스템의 모사를 수행하였다. 또한 에너지 효율을 최대화하기 위하여 열펌프 시스템에서의 환류비의 영향을 규명하였다. 모사결과 이 시스템의 scale up을 위한 정량적인 정상상태 운전조건들을 구할수 있었으며 두 반응의 반응 전화율이 다르더라도 반응물의 유량의 차이를 통하여 두 반응열이 거의 같아지는 것을 알수 있었다. 아울러 주어진 운전조건에서 증류의 환류비는 최소환류비 근처의 최적값이 존재함을 알수 있었다.

• Journal of Chest Surgery
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• v.31 no.2
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• pp.168-172
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• 1998

Inferior sinus venosus defect is a rare lesion in which there is a large interatrial communication adjacent to the atrial connection of the inferior caval vein. The defect is located posteriorly and inferiorly, outside the confines of the true atrial septum, and partial anomalous pulmonary venous connections are the rule. We underwent surgical repair in four patients with inferior sinus venosus defect and partial anomalous pulmonary venous return. There were three males and one female with an age range from four months to 25 years. A cross- sectional echocardiogram and cardiac catheterization had been performed preoperatively in all patients, but the correct diagnosis had been made in only one case. Surgical repair was indicated due to congestive heart failure, and one patient of 4-month-old needed urgent operation. The repair was accomplished by suturing a untreated autologous pericardial patch to the right of the pulmonary veins, so that the defect was closed and all the pulmonary venous blood was directed to the left atrium. The preoperative knowledge of the unusual anatomy allows the surgeon to repair the anomaly without difficulties. For the patients in whom interatrial communication and anomalous pulmonary venous return are suggested, surgeon has to pay careful attention to the anatomical landmarks to avoid incorrect placement of the patch.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.7
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• pp.914-920
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• 2012

We investigated the effects of heat treatment and extraction method on the antioxidant activities of five medicinal plants: Cyperus rotundus, Eucommia ulmoides, Bupleurum falcatum, Achyranthes japonica Nakai, and Akebia quinata. Extraction was performed with only ultrasound, ultrasound after heating at $130^{\circ}C$ for 2 hours, and reflux extraction with distilled water. The phenolic contents of reflux extraction and ultrasound extraction after heating were higher than only ultrasound extraction, and ultrasound extraction after heating samples was higher than reflux extraction except for Eucommia ulmoides and Cyperus rotundus. Total flavonoid content was higher in reflux and ultrasound extraction after heating samples than only ultrasound extraction, except for Cyperus rotundus. ABTS radical scavenging activity was higher in reflux extraction and ultrasound extraction after heating a sample, than only ultrasound extraction. DPPH radical scavenging activity was higher in reflux extraction except for Achyranthes japonica Nakai and Akebia quinata. The reducing power of ultrasound extraction after heating was higher with Achyranthes japonica Nakai. From the results of this study, we can expect to increase the antioxidant activity of medicinal plant extracts by applying suitable extraction and pretreatment conditions on the type of medicinal plant.

• Journal of Chest Surgery
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• v.29 no.3
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• pp.292-296
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• 1996

Total anomalous pulmonary venous return is a rare but serious cardiac malformation, accounting for only about 1.5~3% of congenital heart disease. Surgical results have been dramatically improved in the last two decades, largely owing to improved techniques of cardiopulmonary bypass and perloperative management. Seven patients ranging in age from 15 days to 11 years with total anomalous pulmonary venous return underwent repair between 1984 and 1995. The types of anomalous return were supracardiac in 5, and cardiac in 2. There were 5 boys and 2 girls. There were two hospital death, occurred in 15-day-old, and 40-day-old infants with supracardiac type. Follow-up periods have ranged from 3 months to 11 years, and all survivors have remained asymptomatic with normal growth and development.