• 대한설비공학회지:설비저널
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• 제14권1호
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• pp.1-11
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• 1985

Solar/absorption cooling system was analyzed and its operating condition was examined. For the system, the optimum size of absorption refrigerator and collector area should be determined. As the temperature of water supplied to the generator increases, the collector efficiency decreases whereas the coefficient of performance of absorption refrigerator increases up to a certain point, and vice versa for decreasing of the temperature of water supplied to the generator . Thus if the reeling load is given, the appropriate operating condition can be determined between the two opposing trends by simulation program. As an example of the simulation, the case of Jejudo province was studied. Under the conditions (such as weather data and prices of components, etc.) given en the sample calculation, the result shows that the optimum temperature of water supplied to the generator turned out to be $80.3^{\circ}C$, and still shows a large economical disadvantage in present stage compared to the case of conventional vapor compression cooling/heating combined heat pump system.

• Earthquakes and Structures
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• 제25권1호
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• pp.69-78
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• 2023

Life-cycle performance analysis of a reinforced concrete box section bridge was generated. Moreover, Monte Carlo simulation with important sampling (IS) was used to simulate the bridge material and load uncertainties. The bridge deterioration model was generated with the basic probabilistic principles and updated according to the measurement data. A genetic algorithm (GA) with the response surface model (RSM) was used to determine the deterioration rate. The importance of health monitoring systems to sustain the bridge to give services economically and reliably and the advantages of fiber-optic sensors for SHM applications were discussed in detail. This study showed that the most effective loss of strength in reinforced concrete box section bridges is corrosion of the reinforcements. Due to reinforcement corrosion, the use of the bridge, which was examined, could not meet the desired strength performance in 25 years, and the need for reinforcement. In addition, it has been determined that long-term health monitoring systems are an essential approach for bridges to provide safe and economical service. Moreover the use of fiber optic sensors has many advantages because of the ability of the sensors to be resistant to environmental conditions and to make sensitive measurements.

• Journal of Nutrition and Health
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• 제6권2호
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• pp.35-43
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• 1973

This study is concerned with the nutritional status of the packed lunch boxes which are brought by the junior high school students in Capital City of Seoul. Four hundred and eights students of the 8 school districts in Seoul had been randomly selected as subjects. The contained nutrients in the packed lunch were analysed by the Food Composition Table. To observe the influence of home economical status and mother's educational level on the nutrient concents of packed lunches, the chosen subjects were classified into three large groupings, which are upper, middle and low classes respectively. In addition, comparison between the Recommended Daily Allowanced for Korean people-13 to 15 age group-and the contained nutrients in the lunch boxed had been conducted. T-test was applied to clarify the significance of the differences between each group both economical and educational level. 1. The averaged rations between the Recommended Daily Allowances and the contained nutrients in the lunches stand: Calorie 59.7% (566 Cal.) protein 53.1% (18g), animal protein 48.6% (5g), fat 39.8% (5g), calcium 371.% (0.1g), ferret 66.4% (2.9g) Vitamin A 642 1.U. (31.3%), Vitamin $B_1$ 70.2% (0.3mg), Vitamin $B_2$ 41.4% (0.2g), Niacin 77.0%(4mg), Vitamin C 51.9% (13mg). All of the nctrients fall far behind the Recommended Daily, Allowances for 13 to 15 age group. 2. Home economical status brings influence on the kinds of foods which could been. Protein, animal protein, fat, Vitamin $B_2$, Vitamin C showed significance of diffierences between the upper and middle classes. Between the middle and low classes, Protein, animal protein, fat, calcium and Vitamin C showed significance of difference. And finally, between the upper and low classes, protein, fat, calcium, ferret, Vitamin $B_2$ and Vitamin C showed a great significance. 3. Regardless to the living conditions of the subject students, all the nutrients of the lunches packed by the mothers in the entire educational levels did not reach the Recommended Daily Allowances. Protein, animal protein, fat, ferret, Vitamin A, and Niacin showed the significance of the differences between the upper and middle classes. On the other hand, calorie, animal protein, fat, Vitamin A and Vitamin C showed the significance between the middle and low classes. Between the upper and the low classes, protein, animal protein, fat, and ferret showed significance. 4. The mairdish-ice of the lunch boxes supplied calorie, protein, Vitamin $B_1$, Vitamin $B_2$ and Niacin which stand at 83.8%, 56.1%, 52.5%, and 54.8% respectivly when compared with the whole nutritional contents. 5. The side-dishes of the packed lunch lack in variety of cooking methods. One interesting fact is that entire subject students are very favorable to the food cooked with every kind of grains.

• 지질공학
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• 제27권1호
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• pp.41-49
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• 2017

본 연구는 수치해석을 통해 구근체, 보강재 변화와 지반 조건 변화에 따른 지반 내 영향범위를 확인하고자 하였다. 구근체의 증가에 따른 보강효과 증가 폭을 확인하고 지반조건 변화에 따른 경향을 파악하게 되면 쏘일네일링의 보강재 및 구근체를 결정할 수 있게 되어, 경제적인 시공이 되도록 기초자료로 활용할 수 있을 것으로 판단된다. 본 논문에서는 범용 수치해석 프로그램인 MIDAS GTS NX를 활용하여 보강재 위치 별 하중에 따른 변위를 분석 하였다. 또한 쏘일네일의 인발하중에 따른 사질토, 화강풍화토 지반에서 보강재의 구근체 이완영역이 지반 내 어떠한 특성을 나타내는지 비교 분석 하여 구근체 크기와 보강재의 직경 별 경제성을 확보할 수 있는 기준을 선정하기 위한 수치해석을 수행하였다.

• 한국염색가공학회지
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• 제20권2호
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• pp.19-28
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• 2008

The objective of this study was to apply the statistical technique known as design of experiments to optimize the % exhaustion variables for phthalocyanine dyeing of nylon fiber. In this study, a three-factor Central Composite Rotatable Design (CCRD) was used to establish the optimum conditions for the phthalocyanine reactive dyeing of nylon fiber. Temperature, pH and liquor ratio were considered as the variable of interest. Acidic solution with higher temperature and lower liquor ratio were found to be suitable conditions for higher % exhaustion. These three variables were used as independent variables, whose effects on % exhaustion were evaluated. Significant polynomial regression models describing the changes on % exhaustion and % fixation with respect to independent variables were established with coefficient of determination, R2, greater than 0.90. Close agreement between experimental and predicted yields was obtained. Optimum conditions were obtained using surface plots and Monte Carlo simulation techniques where maximum dyeing efficiency is achieved. The significant level of both the main effects and interaction was observed by analysis of variance (ANOVA) approach. Based on the statistical analysis, the results have provided much valuable information on the relationship between response variables and independent variables. This study demonstrates that the CCRD could be efficiently applied for the empirical modeling of % exhaustion and % fixation in dyeing. It also shows that it is an economical way of obtaining the maximum amount of information in a short period of time with least number of experiments.

• Journal of Korean Society for Atmospheric Environment
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• 제15권E호
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• pp.17-28
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• 1999

Gas-liquid contact tests above a perforated-plate were conducted with air and water at flooding gas-flow conditions in order to study two-phase flow characteristics in a limestone-gypsum SO2 absorber. Gas layers were in the form of air pockets and confined to the limited areas around each duct pipe, while the remaining tary area were in the wet condition. The liquid above the tray was always in the flooded and even fluidized conditions at gas flows over the range studied, although vigorous bubbly or churn-turbulent two-phase regime was only observed in the immediate vicinity of the gas hole exit at low gas loads. The froth zone was extremely active to provide intimate contact between gas and liquid so that the necessary mass transfer operation can take place, which is the primary purpose of high-performance SO2 absorbers. Howefer, the absorber $\Delta$P was 250mmH2O for the initial water level at 150mm, which is an important issue to be resolved for economical operation of the SO2 absorber. It was seen in the liquid level-and gas flow-transient tests that changes in the absorber liquid inventory were much more pronounced for intimate gas-liquid contact than changes in the gas flow. Based on the 4- and 8-duct pipe test results, grouping the duct pipes near the center of the test tray seemed to promote better recirulation of liquid from gas-liquid contact zone back to the reaction tank so that the absorbed SO2 can be neutralized.

• 한국농촌생활과학회지
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• 제6권2호
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• pp.109-119
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• 1995

The objectives of this study were 1) to identity the living conditions of old women at rural area, 2) to inquire of the activities for extra income 3) to Provide information on the social service program development for old rural women. Data were collected by interview with the questionaire from 396 old rural women in Korea. In analyzing data, $x^2$-test has been produced by S A S program package at Rural Development Administration. The major results were as follows ; 1. The average age was 69.7years old of the subjects, illiteracy was 54.1%, widows was 58.6%, and the 18.4% of elderly have led a solitary life. Also, the degree of health care was very low. 2. The source of living costs in most old rural women lay on agricultural income. Also, because of the educational expenditure for their children, etc., they led to poverty, and then could not provide for their old age. 3. In spite of the 60.4% of the old women did farming, a lot of them wishes to have a side job. The reasons why they wish to do a side job were making money, spending their time in working, being proud before their children, etc.. 4. According as they rely on their husband, the eldest son and his wife, for the psychological, physical, economical support, their position among family was low. Therefore, only the 43.3% of old women were satisfied with their life. 5. Finally, in the result of this case study, the old women, who particpate in the extra income promoting program, were satisfied with their rural life, and their social position were high rather than elswhere.

• 한국기계가공학회지
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• 제16권2호
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• pp.28-33
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• 2017

Recently, the operation of precision pocket machining has been studied for the high speed and accuracy in industry to increase production and quality. Moreover, the demand for products with complex 3D free-curved surface shapes has increasing rapidly in the development of computer systems, CNC machining, and CAM software in various manufacturing fields, especially in automotive engineering. The type of aluminum (Al6061) that is widely used in aerospace fields was used in this study, and end-mill down cutting was conducted in fillet cutting at a corner with end-mill tools for various process conditions. The experimental results may demonstrate that the end mill cutter with four blades is more advantageous than that of the two blades on shape forming in the same condition precise machining conditions. It was also found that cutting forces and tool deformation increased as the cutting speed increased. When the tool was located at $45^{\circ}$ (four locations), the corner was found to conduct the maximum cutting force rather than the start point of the workpiece. The experimental research is expected to increase efficiency when the economical precision machining methods are required for various cutting conditions in industry.

• 한국미생물·생명공학회지
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• 제31권3호
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• pp.257-263
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• 2003

고체상태배양에서 섬유소분해효소의 고 생산을 위해 기질로서 다양한 섬유순폐기물을 검토한 결과, 주정박과 볏짚을 1:1의 혼합기질로 사용하였을 때 13.98 FPA를 얻었다. 효소생산을 높이기 위해 주정박과 볏짚의 혼합기질에 질소원으로서 콩비지를 1:1:1로 혼합하였을 때 15.22 FPA의 효소활성을 얻을 수 있었다. 이때의 최적의 함수율, pH, 온도는 각각 70%, 5.0, 3$0^{\circ}C$이었다. 최적배양조건에서 배양 5일째 FPA, CMCase, Xylanase, $\beta$-glucosidase 및 Avicelase의 효소활성은 각각 15.22, 69.1, 83.9, 29.2 및 4.2 unit/g-SDW이었다. T. harzianum FJI의 섬유소폐기물을 이용한 고체상 태배양의 경제적인 효소생산은 섬유소폐기물의 생물학적 당화기술에 크게 기여할 것이다.

• 한국환경복원기술학회지
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• 제17권1호
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• pp.13-25
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• 2014

The study aims to investigate and analyze actual situations of managing topsoil at forest development sites based on their types, in pursuit of conservation and effective use of national land. To do this, I selected target areas by deducting the typical types of forest development and analyzed the condition of soil at the target areas before and after development. In addition to this, I interviewed associated construction staffs to conduct study on present situations of topsoil management and find out its problems. I also surveyed of relevant experts, with the intention of seeking solutions. The results of the study have been shown that firstly, experts preferred collecting and recycling of topsoil as methods of improvement of soil conditions for plant growth. Secondly, the importance of topsoil has been well noticed and there were few construction sites using the methods. However, working and economical problems have disturbed carrying out these solutions. Thirdly, after constructions, organic matter and total-nitrogen content decreased in general which were necessary for plant growth in terms of soil conditions.