• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2150-2156
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• 2018

We suggest a systematic method for obtaining the optimal compression ratio in the multi-stage closed-loop compression process of carbon dioxide. Instead of adopting the compression ratio of 3 to 4 by convention, we propose a novel approach based on mathematical analysis and simulation. The mathematical analysis prescribes that the geometric mean is a better initial value than the existing empirical value in identifying the optimal compression ratio. In addition, the optimization problem considers the initial installation cost as well as the energy required for the operation. We find that it is best to use the fifth stage in the general closed-loop type carbon dioxide multi-stage compression process.

• 보건행정학회지
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• 제10권4호
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• pp.75-98
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• 2000

This study applied Data Envelopment Analysis(DEA) and Ratio Analysis and Regression Analysis to a set of Korean Public Corporation Medical Centers to evaluate their relative human resource efficiencies. The output measure used in this study was based on health insurance system which was used in both in-patient departments and out-patient departments. Inputs included working time of the doctors, nurses, technicians, and managerial department staff. Based on the data provided on the inputs and outputs, the analysis showed 23 of the 34 hospitals to be relatively inefficient. Each hospital with an efficiency rating of less than 1 was considered relatively inefficient. In addition, managerial strategies based on dual variables were constructed to indicate the manner In which inefficient hospitals may be made efficient. A subsequent analysis of t-test revealed that the bed occupancy rate, medical revenue per 100beds, value added revenue per staff, medical revenue per staff were statistically significant. The results of this study suggest the DEA is a promising tool for evaluating relative human resource efficiency in hospitals which have multiple inputs and outputs and where the efficient production function is not specifiable with any precision. But it is considered that efficiency evaluations may be most effective]y accomplished by Incorporating a combination of methodologies such as ratio analysis and regression analysis.

• International Journal of Aerospace System Engineering
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• 제8권1호
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• pp.1-13
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• 2021

Contra-rotating fan is comprised of two rotors which are rotating in the opposite direction. The fan stages are named rotor-1 and rotor-2. Benefits from the use of contra rotation are in terms of better efficiency and improved thrust to weight ratio. Failure of contra-rotating fan stage blade in-service results in safety risks, repair costs, and revenue losses. This paper focuses on the vibration analysis and one way fluid-structure interaction of high aspect ratio, low speed contrarotating fan rotors. Modal analysis and modal pre-stress analysis of contra-rotating fan rotors were carried out to calculate the natural frequencies, One way fluid-structure interaction (FSI) was carried out where the computational analysis of the blades was performed using ANSYS CFX. The boundary conditions for CFD analysis were considered from the actual experimental velocity flow field at the inlet and pressure outlet. Based on the results obtained from the CFD analysis, the structural analysis such as deformation and Von-Misses stresses was carried out by using the finite element method (FEM) with ANSYS. The results provide necessary guidelines for the safe running of the contra-rotating fan. The analysis also will be helpful to understand the change of flow behavior due to a rotor deformation.

• 한국전문물리치료학회지
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• 제6권3호
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• pp.82-93
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• 1999

Stroke is a serious disease despite recent improvement in medical and surgical treatment. Hence, identification of modifiable risk factors for stroke is important. This case-control study was done to demonstrate that relationship between smoking, alcohol consumption, obesity, perception of saltness and the incidence of stroke and to identify that smoking, alcohol consumption, obesity and perception of saltness, after adjusting for age, hypertension. A structured interview was carried out from April 15, 1996 to May 3, 1996 in Yonsei Medical Center. The study group consisted of 59 neurologically confirmed stroke patients as the study group and 59 non-stroke patients as controls. Analysis of the data was done by means of ${\chi}^2$-test and logistic regression analysis. The results were as follows. In the study group: 1) Hypertension in males had a 10.2 odds ratio (p<0.05), cardiovascular disease in females had a 11.3 odds ratio (p<0.05) and a farnily history of stroke in males had a 3.1 odds ratio (p<0.05). 2) Females smoking one or more cigarettes had a 8.3 odds ratio (p<0.1), but males had no direct relationship with odds ratio of 1.5 (non-significant). 3) Alcohol consumption in males had a 0.4 odds ratio, and in females had a 0.8 odds ratio. The odds ratio was decreased in alcohol consumption group (non-significant). 4) Males with more than 20 cigarettes pack-years history had a 2.5 odds ratio (p<0.05), more than 25 Body Mass Index had a 3.1 odds ratio (p<0.05) and more than 220 ml ethanol weekly consumption had a 1.5 odds ratio (non-significant). 5) Female smokers had a 8.3 odds ratio (p<0.1), drinkers a 0.8 odds ratio and more than 25 Body Mass Iidex, a 43.1 odds ratio (p<0.05). 6) Females without saltness perception from a 0.5% salt solution had a 6.8 odds ratio (non-significant). 7) By logistic regression analysis independent risk factors for stroke in males were found to be hypertention, age, and obesity. The study was limited because number of subjects was too small for practical implications. However, like as other results, this study suggest that people should be advised to control hypertension, and obesity since these carry a risk of stroke.

• 한국보건간호학회지
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• 제31권2호
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• pp.376-388
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• 2017

Purpose: The triglyceride-to-high-density lipoprotein-cholesterol (TG/HDL-C) ratio is one of the main predictive indices for cardiovascular disease. This study was examined the relationship between TG/HDL-C ratio and metabolic syndrome (MetS) in male office workers. Methods: Secondary analysis was conducted to determine the risk between the TG/HDL-C ratio and MetS in male office workers. A total of 765 people underwent the 'regular workplace health checkups in 2014'. Among the subjects who were male and responded to the questionnaire and health lifestyle survey, 470 (61.4%) excluding those with missing and/or abnormal values were analyzed. The association between MetS, MetS components, and the TG/HDL-C ratio was examined by a Chi-square test, One-way ANOVA, Turkey post-hoc test and Logistic regression analysis. Results: The number of males with MetS was 70 (14.9%) and the number of MetS components increased with increasing TG/HDL-C ratio (p<.001). Logistic regression analysis with an adjustment for potential confounders revealed a 31.8 times higher odds ratio of the Quartile4 group for MetS than that of the Quartile1 group (p<.001). Conclusion: These results show that the likelihood of MetS, particularly the risk of MetS in the Quartile4, increases with increasing TG/HDL-C ratio.

• 한국환경복원기술학회지
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• 제16권1호
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• pp.207-225
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• 2013

Current ecological stream restoration is focusing on recovery of physical characteristic and ecological functions of individual stream. For effective stream restoration, the relationship between stream environment and riparian flora should be investigated. The purpose of this study is to analyze the relationship between disturbance of hydromorphological structures and naturalized plants ratio in small to mid-sized streams. For the study sites, Gwanpyeong stream, Dongdal stream, and Yongchoo streams were chosen as 'reference stream' while, Gunnam stream, Anchang stream, and Hwa stream were chosen as 'damaged stream'. The hydromorphological structures of streams were evaluated with LAWA and flora of the streams were completely enumerated to calculate naturalized plants ratio. The result showed that there was a significant correlation between the outcome of LAWA and naturalized plants ratio(r=0.675, p<0.01). The result of factor analysis of LAWA identified three factors, 'River front and land use', 'River bed materials and structures', and 'Crossing structure and bar'. Among the factors of hydromorphological structures given by the result of factor analysis, 'river front and land use' and 'bed materials and structures' have statistically significant relationship with naturalized plants ratio($R^2$=0.470, p<0.01). Given this results, quantitative analysis on the relationship between disturbance of hydromorphological structures of streams and naturalized plants ratio could provide some essential information for stream restoration. Also, as this study figured out major factors of hydromorphological structures that affect naturalized plants ratio, it might help monitor ecological states and current problems of small and mid-sized streams.

• Asian Pacific Journal of Cancer Prevention
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• 제15권5호
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• pp.2369-2374
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• 2014

Background and Aim: Selumetinib is a promising and interesting targeted therapy agent as it may reverse radioiodine uptake in patients with radioiodine-refractory differentiated thyroid cancer. We conduct this metaanalysis to compare the efficacy and safety of selumetinib with current therapies in patients with advanced cancer. Methods: An electronic search was conducted using PubMed/ Medicine, EMBASE and Cochrane library databases. Statistical analyses were carried out using either random-effects or fixed-effects models according to the heterogeneity of eligible studies. Results: Six eligible trials involved 601 patients were identified. Compared with current therapies, treatment schedules with selumetinib did not improve progression free survival (hazard ratio, 0.91; 95%CI 0.70-1.17, P= 0.448), but did identify better clinical benefits (odds ratio, 1.24; 95%CI 0.69-2.24, P = 0.472) and less disease progression (hazard ratio, 0.72; 95%CI 0.51-1.00, P = 0.052) though its impact was not statistically significant. Sub-group analysis resulted in significantly improved progression free survival (hazard ratio, 0.61; 95%CI 0.49-0.57, P = 0.00), clinical benefits (odds ratio, 3.04; 95%CI 1.60-5.77, P = 0.001) and reduced disease progression (hazard ratio, 0.35; 95%CI 0.18-0.67, P = 0.001) in patients administrated selumetinib. Dermatitis acneiform (risk ratio, 9.775; 95%CI 3.143-30.395, P = 0.00) and peripheral edema (risk ratio, 2.371; 95%CI 1.690-3.327, P = 0.00) are the most frequently observed adverse effects associated with selumetinib. Conclusions: Compared with current chemotherapy, selumetinib has modest clinical activity as monotherapy in patients with advanced cancer, but combinations of selumetinib with cytotoxic agents in patients with BRAF or KRAS mutations hold great promise for cancer treatment. Dermatitis acneiform and peripheral edema are the most frequently observed adverse effects in patients with selumetinib.

• 한국건설관리학회논문집
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• 제6권2호
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• pp.61-68
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• 2005

지역별 적정 주택량을 공급하기 위해 수요예측 모형을 구축한다 예측모형은 자료유형에 따라 다소 차이가 있으나 시계열자료(Time Series Data) 분석기법에 의한 모형 구축 시 추정대상 지역특성을 민감히 반영할 수 있는 영향인자가 필요하다. 도시지역을 인구규모로 분류하여 영향인자를 분석할 경우, 대도시와는 달리 중 $\cdot$ 소도시는 주택량과 상수도보급률의 변화가 일정기간 민감한 상관관계가 존재하는 것으로 조사되고 있다. 이에 따라 중 $\cdot$ 소도시 주택수요 예측을 위해 상수도보급률을 유용하게 적용할 수 있는 구간, 즉 예측모형 구축이 가능한 시점까지의 도시 주택량과 인구수 규모를 찾아낼 필요가 있다. 따라서, 전국 중 $\cdot$ 소도시를 대상으로 주택량과 상수도 보급률의 상관관계가 중 소도시 지역에서만 있는 것으로 조사된 기존 연구 결과를 재 입증하고, 지역별 상관관계가 완화되는 시점의 시기, 상수도보급률, 주택량, 인구수 규모를 발견하는 것을 본 연구의 목적으로 한다.

• 한국콘텐츠학회논문지
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• 제14권5호
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• pp.512-523
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• 2014

본 연구는 Flanders 언어상호작용 분석법을 활용하여 대학부설영재원 수학영재 수업에서 교수-학생 간의 언어적 상호작용을 분석한다. 연구문제는 수학영재 수업의 1)Flanders 코드 항목별 결과는 어떠한가? 2)언어형태는 어떠한가? 3)Flanders 지수결과는 어떠한가? 연구대상은 대학부설 영재교육원 중등 수학반 수업이며, 수업과정을 비디오 녹화한 동영상을 AF분석 프로그램 3.54를 활용하여 분석한 결과 1)Flanders 코드 항목별 분석결과, 교사의 비지시적 발언보다 지시적 발언이, 학생의 반응적인 발언보다 자진적인 발언이 많은 것으로 나타났고, 분류 항목별 빈도수는 강의, 학생의 자진적인 말, 활동 등이 전체수업의 대부분을 차지하였다. 2)수업 흐름은 대체적으로 바람직한 수업 흐름 모델을 따르지 않는 것으로 나타나, 학생 발언에 대한 교사의 적절한 피드백이 요구된다. 3)지수 분석 결과, 수정 비지시, 교사 질문비, 학생 발언비, 학생 질문 및 넓은 답변비는 분석기준보다 높게 나타났고, 비지시는 분석 기준보다 낮게 나타났다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.73-78
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• 2000

This paper describes the effect of span-to-depth ratio, which describes aspect of cell formed with top diaphragm steel plate, on capacity in composite steel-concrete structure of sandwich system. The span-to-depth ratio \ulcorner load-carrying mechanism and load-distribution capacity of structure. Therefore, stress levels of members and load-resis\ulcorner of system vary according to span-depth ratio. In this study, numerical nonlinear analysis was performed to various ratio for two types(MA, MB) composite structure of sandwich system to analyze the influence of span-to-depth ratio or, behavior. The difference of load-carrying mechanism and stress of members results from analysis results, then bas\ulcorner differences, the effects of span-to-depth ratio on shear capacity, flexural capacity and load-resistance capacity were analyze effects on failure mode and ductility were briefly. As a results of this study, as span-to-depth ratio increases, \ulcorner bottom steel plate and concrete lower. This implies an increase in effective flexural and shear capacity. Therefore lo\ulcorner capacity of structure improves as span-to-depth ratio increases, Especially, the effect is greate in shear than flexural span-to-depth ratio increases, this difference between flexural and shear capacity may change failure mode and ductility. span-to-depth ratio increases capacity increases more than flexural capacity, we should expect that structural behavior mode gradually change from shear to flexural and ductility of structure gradually improves.