• Tribology and Lubricants
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• 제32권2호
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• pp.50-55
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• 2016

Recently, a double-side machining process has been adopted in fabricating a sapphire glass to enhance the manufacturability. Double-side lap grinding (DLG) is one of the emerging processes that can reduce process steps in the fabrication of sapphire glasses. The DLG process uses two-body abrasion with fixed abrasives including pallet. This process is designed to have a low pressure and high rotational speed in order to obtain the required material removal rate. Thus, the temperature is distributed on the DLG platen during the process. This distribution affects the shape of the substrate after the DLG process. The coolant that is supplied into the cooling channel carved in the base platen can help to control the temperature distribution of the DLG platen. This paper presents the results of computational fluid dynamics with regard to the heat transfer in a DLG platen, which can be used for fabricating a sapphire glass. The simulation conditions were 200 rpm of rotational speed, 50℃ of frictional temperature on the pallet, and 20℃ of coolant temperature. The five cases of the coolant flow rate (20~36 l/min) were simulated with a tetrahedral mesh and prism mesh. The simulation results show that the capacity of the generated cooling system can be used for newly developed DLG machines. Moreover, the simulation results may provide a process parameter influencing the uniformity of the sapphire glass in the DLG process.

• 한국유기농업학회지
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• 제27권3호
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• pp.271-288
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• 2019

It has continuously promoted to scale up the agricultural management body in order to cope with the market-opening pressure such as the UR negotiation, the DDA negotiation, and more conclusions of FTAs and to enhance the competitiveness of our agriculture. This study evaluated the factors associated with production organization participation centered on environmentally-friendly agriculture farmers in order to improve the production efficiency of environmentally-friendly agriculture in the aspect of production. In order to achieve this objective, this study evaluated the factors that contributed to participating in an organization using the bivariate probit model focusing on environmentally-friendly agriculture farmers in Chungnam. This study examined the validity and reliability of the study model through exploratory factor analysis. The results of factor analyses identified four factors: "distribution", "production", "organization operation", and "social capital". The results of the bivariate probit model showed that distribution significantly affected production activities and distribution, organization operation, agricultural income, and gender significantly influenced sale activities. Environmentally-friendly production organization had not been able to provide the productive support that was needed for local farmers to produce environmentally-friendly agricultural products in a region. Additionally, farming education did not provide the information needed by the farmers. Although producers had a network within a production organization, it was operated mainly for administrators. Therefore, participants felt somewhat lacking. This study identified the level of organization of producer organizations in Chungnam area, where environmentally-friendly agriculture is well activated. This study suggested implications for future production organization participation by evaluating factors affecting participation quantitatively.

• Wind and Structures
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• 제25권2호
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• pp.101-129
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• 2017

Local transient extreme wind loads caused by group tower-related interference are among the major reasons that lead to wind-induced damage of super-large cooling towers. Four-tower arrangements are the most commonly seen patterns for super-large cooling towers. We considered five typical four-tower arrangements in engineering practice, namely, single row, rectangular, rhombic, L-shaped, and oblique L-shaped. Wind tunnel tests for rigid body were performed to determine the influence of different arrangements on static and dynamic wind loads and extreme interference effect. The most unfavorable working conditions (i.e., the largest overall wind loads) were determined based on the overall aerodynamic coefficient under different four-tower arrangements. Then we calculated the one-, two- and three-dimensional aerodynamic loads under different four-tower arrangements. Statistical analyses were performed on the wind pressure signals in the amplitude and time domains under the most unfavorable working conditions. On this basis, the non-Gaussian distribution characteristics of aerodynamic loads on the surface of the cooling towers under different four-tower arrangements were analyzed. We applied the Sadek-Simiu procedure to the calculation of two- and three-dimensional aerodynamic loads in the cooling towers under the four-tower arrangements, and the extreme wind load distribution patterns under the most unfavorable working conditions in each arrangement were compared. Finally, we proposed a uniform equation for fitting the extreme wind loads under the four-tower arrangements; the accuracy and reliability of the equation were verified. Our research findings will contribute to the optimization of the four-tower arrangements and the determination of extreme wind loads of super-large cooling towers.

• 소성∙가공
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• 제32권6호
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• pp.311-320
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• 2023

Recently, lightweight of automotive parts has been required to solve environmental problems caused by global warming. Accordingly, research and development are proceeded on manufacturing of parts using aluminum that can replace steel for lightweight of the automotive parts. In addition, high strength aluminum can be applied to body parts in order to meet both requirements of lightening and improving crash safety of vehicle. In this study, hot blow forming of roof side rail is employed to manufacturing of the automotive parts with high strength aluminum tube. In hot blow forming, longer forming times and excessive thinning can be occurred as compared with conventional manufacturing processes. So optimization of process conditions is required to prevent excessive thinning and to uniformize thickness distribution with fast forming time. Mechanical properties of high strength aluminum are obtained from tensile test at high temperature. These properties are used for finite element(FE) analysis to investigate the effect of strain rate on thinning and thickness distribution. Variation of thickness was firstly investigated from the result of FE analysis according to tube diameter, where the shapes at cross section of roof side rail are compared with allowable dimensional tolerance. Effective tube diameter is determined when fracture and wrinkle are not occurred during hot blow forming. Also FE analysis with various pressure-time profiles is performed to investigate the their effects on thinning and thickness distribution which is quantitatively verified with thinning factor. As a results, optimal process conditions can be determined for the manufacturing of roof side rail using high strength aluminum.

• 한국융합학회논문지
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• 제6권3호
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• pp.19-28
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• 2015

본 연구의 목적은 중년기 여성을 대상으로 비만의 원인을 규명하기 위하여 필요한 다양한 관련요인을 분석함으로서 향후 비만 정책방향에 기초자료를 제공하는데 있다. 2014년 4월부터~11월까지 인천지역의 N 병원 건강증진센터를 방문한 건강한 중장년 여성들 중 본 연구의 목적에 동의한 195명의 여성을 대상으로 실시하였으며, 신체계측, 체성분검사, 복부 지방분포는 복부지방단층촬영(Fat-CT)을 이용하였다. 그리고 골밀도는 정량적전산화 단층촬영(Q-CT)을 이용하여 측정하였다. 복부지방단층촬영 결과 '피하지방' 76명(39%), '내장지방'은 119명(61%)이었으며, 체질량지수(BMI)는 '저체중($18.5kg/m^2$)'은 13명(6.7%), '과체중($25kg/m^2$이상)'은 60명(30.8%), 평균값은 $23.5{\pm}4.11kg/m^2$이었다. 그리고 허리둘레, 확장기혈압, 수축기혈압, 중성지방에서 유의수준 5%내에서 통계적으로 유의한 것으로 나타났다. 본 연구의 결과를 통해 나이가 들수록 근육감소가 복부비만으로 인한 체중 증가를 상쇄시킨다는 점을 알 수 있었고, 따라서 비만에 대한 차후연구에서는 이러한 특성을 이해해야 한다.

• Clinical and Experimental Pediatrics
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• 제48권7호
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• pp.745-752
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• 2005

목 적 : 소아 비만의 증가에 따라 소아기에 고혈압, 관상동맥 질환, 당뇨병 등의 소아 성인병이 문제가 되고 있다. 중등도 이상의 비만 청소년에서 경부 초음파로 경동맥의 내피두께, 직경, 동맥의 유연도와 신전도를 측정함으로 조기에 동맥 경화증으로 진행을 예측할 수 있는지 알아보고, 동맥벽 두께와 혈청 사이토카인 등 여러 지표와의 관련성을 알아보고, 비만 청소년에서 관상동맥 질환으로 진행할 수 있는 위험 인자로 유용한지 알아보고자 하였다. 방 법 : 16-17세의 29명의 중등도 이상의 비만 청소년을 대상군으로 하였고, 같은 연령의 정상 청소년을 대조군으로 하였다. 체질량 지수와 피부두께를 측정하였고, 생체전기저항 분석을 이용하여 체지방, 지방 분포를 측정하였다. 안정된 상태에서 수축기, 이완기 혈압을 측정하였다. 10시간 이상 금식 후 총 콜레스테롤, 중성 지방, HDL 콜레스테롤, LDL 콜레스테롤, 혈당, 호모시스틴, 인슐린, 인슐린 저항성을 측정하였다. 경부 초음파를 이용하여 경동맥의 내피 두께, 수축기와 이완기 동안의 내경, 동맥의 유연도와 신전도를 측정하였다. 결 과 : 경동맥의 수축기 내경, 이완기 내경은 상완둘레, 체질량 지수, 지방분포, 체지방이 증가함에 따라 유의하게 증가하였다. 수축기 혈압이 높을수록 수축기 및 이완기 내경이 유의하게 증가하였고, 이완기 혈압이 증가할수록 내피두께는 유의하게 증가하였다. 인슐린치가 증가할수록 수축기 및 이완기 내경이 유의하게 증가하였다. 호모시스틴치가 증가할수록 내피 두께가 유의하게 증가함을 알 수 있었다. 결 론 : 소아에서도 비만 정도가 심할수록, 혈압이 높을수록 경동맥의 내경이 증가하였고, 경동맥의 내피두께는 이완기 혈압과 유의한 상관성이 있었다. 혈압, 인슐린, 호모시스틴을 측정함으로 조기에 동맥경화증으로 진행을 예측하는데 유용하리라 생각되고 소아기 비만에서도 적극적인 체중 감량을 통해 소아 성인병으로 진행되는 것을 적극적으로 예방하여야 될 것으로 생각한다.

• 대한지역사회영양학회지
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• 제7권1호
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• pp.76-85
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• 2002

Since the 1970s, the average life expectancy of Koreans has been increasing. Our concerns are not simply about longevity, but also about disability-free life. lately, Sasang constitutional medicine has attracted public attention, especially with respect to the elderly. The purpose of this study was to investigate the food habits, nutrients intake, and disease distribution among the elderly, according to their Sasang constitutions. The results are as follow : The distribution of constitutions of the subjects were Tae-eum 48.8%, So-yang 27.4%, So-eum 22.6%, and So-yang + So-eum 1.2%. In both elderly men and women, body weight, percent ideal body weight, and diastolic pressure of the Tae-eum were significantly higher than those of other constitutions. In both men and women, the level of hemoglobin in the Tae-eum was significantly higher than those of other constitutions. The level of LDL-cholesterol was higher, and the level of HDL-cholesterol was lower in the So-eum elderly women. Food habits of the So-eum were the most irregular, and nutrients intake of the So-eum was lower than that of other constitutions in both elderly men and women. In elderly men, the incidence of hypertension was the highest in the Tae-eum, and the incidence of gastritis was the highest in both So-yang and So-eum. In elderly women, the incidence of fatty liver was the highest in the Tae-eum and So-yang, and gastritis and hypertension were the highest in the So-eum. In the elderly, obese and anemic persons were significantly more in the Tae-eum and the So-eum, respectively. The results of this study showed that there were significant differences of physical, characeristics, food, habits, and distributions of disease for the subjects according to each Sasang constitutions. Intake of nutrient was poor, regardless of Sasang constitutions, in both men and women.

• 대한약리학회지
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• 제31권2호
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• pp.251-259
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• 1995

Pharmacokinetics and pharmacodynamics of metoprolol, a selective beta-l blocker, were examined for 360 minutes after intravenous bolus administration of metoprolol to 6 dogs. Plasma concentration and excreted amount in the urine metoprolol were measured by liquid chromatography with fluorescence detection. PR interval and heart rate were measured by ECG monitoring. Blood pressure was monitored through intraarterial catheter in femoral artery and cardiac output by thermodilution method using Swan-Ganz catheter. To analyze the effect site concentration-response relationship, plasma concentration and pharmacological effects were simultaneously fitted to a two pharmacokinetic compartment linked to pharmacodynamic model with NONLIN program. Results are as follows. 1) The plasma concentration of metoprolol after intrvenous injection decreased biexponentially. The terminal half-life estimated was $1.33{\pm}0.40$ hours and the volume of distribution at steady state (Vdss) and the total body clearance were $1.04{\pm}0.4\;L/kg,\;6.55{\pm}2.21\;L/hr$, respectively. The central compartment volume of distribution and peripheral compartment volume of distribution were $0.35{\pm}0.14L/kg\;and\;0.69{\pm}0.34L/kg$. The renal clearance and intercompartment clearance were $0.53{\pm}0.25\;L/min\;and\;0.35{\pm}0.19\;L/min$. 2) Simulated biophase concentration-response curve shows hyperbolic relationship and the estimated concentration-effect relationship was best explained by Emax model when the prolongation of PR interval and the reduction of the heart rate were used as pharmacodynamic parameters. Emax and EC50 were estimated to be $26.3{\pm}4.7\;msec\;and\;88.8{\pm}82.3\;g/ml$ for PR interval, and $48.7{\pm}18.8\;beats/min\;and\;113.5{\pm}78.7\;ng/ml$ for heart rate, respectively. 3) The changes of cardiac output-effect site concentration relationship was best fitted by a linear model and the slope of the relationship was $0.005{\pm}0.003$. Diastolic blood pressure-effect site concentration relationship was also explained by the linear model and the slope of the relationship was $0.038{\pm}0.034$.

• 대한가정학회지
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• 제24권4호
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• pp.57-68
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• 1986

The present survey was designed to investigate correlations among blood pressure, nutritional intakes, and various environmental factors in Korean adult males, and to observe the difference in dietary intakes between hypertensive patients and normotensive subjects. Two hundred forty-three adult men from Seoul and rural areas were interviewed about their food intakes, dietary patterns, food habits, and general environmental factors from December 20, 1982 to February 15, 1983. Their dietary intakes were surveyed by means of 24-hour recall diet method. Dietary score card was used in order to evaluate the quality of routine diet of the subject. Variables of environmental factors and factors related to hypertension were expressed as percentage, and the differences in nutrient intake and food score of each sub-group were examined by means of t-test. Correlation of all the variables were analyzed by Pearsons Correlation Coefficient. The results obtained are summarized as follows: 1. 38% of the subjects were between the ages of 40~49, and about one-half of the subjects were middle or high school graduates. 28% of the subjects earned 210, 000~350, 000 Won per month, and income distribution was almost identical to that of the urban population of Korea. 2. There was more overweight or obese found in the hypertensive patients than in the normotensive subjects. About 40% of the hypertensive patients reported a family history of hypertension, and their knowledge about hypertension was rather poor, but slightly better than the normotensive subjects. The patient group had less adherence to smoking and alcohol compared with the normotensive subjects, but no difference was observed in coffee drinking. The mean value of the blood pressure for the normotensive subjects was 127/86mmHg and 175/109mmHg for the hypertensive group. 3. Nutrient intake for the hypertensive group was lower for most of nutrients than in the healthy group. Hypertensive patients on diet therapy consumed less calories and carbohydrates compared with those who do not follow diet therapy. 4. There was no difference intake of these food groups between patients and the healthy group. Food score was strongly related to consumption of animal protein, saturated fats, Calcium, Iron, Vitamin A, Riboflavin, and Vitamin C, which are prone to be deficient in the typical Korean diet. 5. Blood pressure had a strong positive correlation with age, body weight, and socioeconomic level. In addition, monthly income was positively related with age and education level. 6. Three was a positive relationship between blood pressure and consumption of vegetable protein, and a negative relationship with consumption of Calories, Carbohydrates, Calcium, Iron, Vitamin A, Vitamin B1, Niacin, and Vitamin C. Animal protein intake increased as income and education levels increased, but this tendency was opposite for carbohydrates. In summary, nutritional intakes are strongly correlated with various environmental factors and the level of blood pressure. There was no difference between normotensive and hypertensive subjects with respect to the quality of food consumed except restricting energy and carbohydrate in the patient group.

• 대한방사선치료학회지
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• 제22권1호
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• pp.11-18
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• 2010

목 적: 방사선 치료에서 매번 치료를 시행할 때마다 호흡에 의한 해부학적인 내부 장기의 움직임과 환자자세의 변화에 따라 치료부위 오차가 발생한다. 이런 치료부위 오차의 발생은 치료부위와 정상 조직 간의 선량분포의 변화에 영향을 줄 수 있는 원인이 된다. 간암 환자 치료 시 Body-fix의 사용 유무 차이에 따른 임상치료에서의 유용성을 알아보고자 한다. 대상 및 방법: 본원에서 2009년 10월부터 2010년 7월까지 Hi-Art Tomotherapy를 시행 받은 55~60세 사이의 남자환자 중에서 간의 Couinaud 분류 중 V~VI 구역에서 간세포성 암(Hepatocellular carcinoma)이 발생한 환자 10명을 대상으로 Body-fix 사용 유무에 따라 2 그룹으로 분류하여 조사하였다. Body-Fix를 사용 시 진공펌프(Vacuum pump, Medical intelligence, Germany)를 이용하여 80 mbar의 압력으로 진공상태를 유지하였다. 환자는 정상호흡(free breathing)을 유지한 상태에서 바로누운자세(supine position)로 치료 시작부터 5회 치료 시 획득한 MV-CT (Megavoltage computed tomograpy, MVCT)와 KV-CT(Kilovoltage computed tomograpy, KVCT)을 융합하여 일치시키는 작업 후 X축의 좌우방향(Right to Left, RL), Y축의 상하방향(Craniocaudal, CC), Z축의 전후방향(Anterioposterior, AP)에서의 발생하는 방사선 치료 준비오차를 측정하여 비교 분석하였다. 결 과: 영상융합을 통한 평균 방사선 치료 준비오차는 A 그룹에서 $0.3{\pm}1.1\;mm$ (상하), $-1.1{\pm}0.7\;mm$ (좌우), $-0.2{\pm}0.7\;mm$ (전후)이었다. B 그룹에서는 $0.62{\pm}1.94\;mm$ (상하), $-3.62{\pm}1.5\;mm$ (좌우), $-0.22{\pm}1.2\;mm$ (전후)로 이동하였다. 두 그룹간의 Body-fix의 사용유무에 따른 X축, Y축, Z축 방향의 편차는 최대 X축(좌우) 5.5 mm, Y축(상하) 19.8 mm, Z축(전후) 3.2 mm로 측정되었다. 또한 오차방향의 분석과 관련하여 모든 환자에 일관성이 존재하지는 않지만 Body-Fix를 사용 시 매일 환자자세 변화와 호흡변화가 발생함에도 불구하고 방사선 치료 준비오차에 대한 위치 변화가 안정적인 양상의 결과를 보여준다. 결 론: 간암 환자 치료 시 Body-Fix의 사용은 방사선 치료 준비오차가 환자자세와 호흡변화에도 불구하고 각 그룹간의 편차가 발생하는 가운데에 안정적이며 규칙적이므로 Tomotherapy와 같은 고 정밀 치료에 효과적으로 사용되리라 사료된다.