• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.2
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• pp.53-61
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• 2023

Most of the sewage sludge is organic waste containing a large amount of organic substances decomposable by microorganisms by biological treatment. As for existing sewage sludge treatment methods, reduction and fuel conversion are being carried out using technologies such as drying, incineration, torrefaction, carbonization. However, the disadvantage of high energy consumption has been pointed out as latent heat of 539 kcal/kg is consumed based on drying. Therefore, in this study, we intend to produce solid fuel through hydrothermal carbonization(HTC), which is a thermochemical treatment. To evaluate the value of solid fuel, the characteristics of carbonization and fuel ratio were analyzed. As a result, as the hydrothermal carbonization reaction temperature increased, the lower heating value also increased by about 500 kcal/kg due to the increase in the degree of carbonization. H/C, O/C, ratio showed a decreasing trend from 1.78, 0.46 to 1.57, 0.32. When the ratio of ash to combustible content (fixed carbon + volatile) of dry sludge was 0.25 or more, it was derived that the degree of carbonization and calorific value did not increase even when hydrothermal carbonization was performed.

• Journal of Korean Society of Forest Science
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• v.94 no.3 s.160
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• pp.135-145
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• 2005

The purpose of this study is to reveal the component characteristics and the channels of distribution for forest products as a fuel that were consumed in Kyeongseong city (Seoul) in 1929, in the middle of the colonial period. The summary of the results are as follows; (1) though the average consumption of forest products consumed as a fuel per household in Kyeongseong city was slightly less than one-third as much forest products as fuel consumed in other counties of Kyeongki province, but due to the high heat capacity, the amount of fuelwood and charcoal consumption was much higher than leaf and grass consumption; (2) the largest supply areas of forest products for fuel were the riverside of Kangwon province and Kyeonggi province in which the waterways were available. They supplied 42.6% of total consumption, and the other supply areas were the northern part of Kyeonggi province, etc. (29.5%) where railroads were handy, and the suburbs of Kyeongseong City (27.9%) by roads; (3) the transportation areas using the Han River were divided into two parts of Ttook island (43.0%) and former Yongsan and Mapo (45.6%), but the volume of transportation by railroad was centralized in Kyeongseong Station, which accounted for 72.2% of total volume of transportation by rail; (4) the most of the forest products consumed for fuel in Kyeongseoung city were sold in temporary fuelwood markets, rather than permanent and regular markets.

• Journal of the Korean Society of Food Culture
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• v.6 no.4
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• pp.393-401
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• 1991

In order to compare the food consumption pattern of college girls on weekday and Sunday, the food intake of college girls in a district of Pusan city was analyzed through the factor analysis method. The principal results are as follows. 1. The amount of food intake on Sunday was generally larger than the average values of the food intake on weekday except for soybean & products, meats and beverage. 2. As for correlation coefficients among the intake of each food group, on weekday, positive correlation was noted among rice, potatoes, soybean & products and sea-weeds, fish & shells and fat & oil. And confectionery & sugar showed also a positive correlation to bread, while, on Sunday, vegetables, sea-weeds and meats showed a positive correlation to rice, and other cereals and eggs showed a positive correlation to bread & noodles, too. As for the relationship among rice and bread & noodles, a negative correlation was noted both on weekday and Sunday. 3. As for the factor analysis of the food intake on weekday through the correlation matrix, in the first factor, soybean & products, fat & oil, sea-weeds, rice and fish & shells showed comparatively large factor load, and in the second factor, meats, kimchi, vegetables, soybean & products, fruits and fish & shells showed large factor load. Here the first factor showed the Korean dietary life and the second factor showed subsidiary food (control nutrient) factor. In case of the food intake on Sunday, in the first factor, rice, meats, sea-weeds, soybean & products and vegetables showed large factor load, and in the second factor, fish & shells, vegetables, fat & oil, fruits and rice showed large factor load. Accordingly, the first factor and the second factor were considered to show Korean dietary pattern. 4. Nutrient intake on weekday and Sunday was substantially sufficient to RDA except for energy and iron.

• Journal of Bio-Environment Control
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• v.17 no.2
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• pp.90-95
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• 2008

It has become a big matter of concerns that the skill and measures against reduction of energy and cost for heating a protected horticultural greenhouse were prepared. But in these days necessity of cooling a protected horticultural greenhouse is on the rise from partial high value added farm products. In this study, therefore, a horizontal type geothermal heat pump system with 10 RT scale to heat and cool a protected horticultural greenhouse and be considered to be cheaper than a vertical type geothermal heat pump system was installed in greenhouse with area of $240\;m^2$. And cooling performances of this system were analysed. As condenser outlet temperature of heat transfer medium fluid rose from $40^{\circ}C$ to $58^{\circ}C$, power consumption of the heat pump was an upturn from 11.5 kW to 15 kW and high pressure rose from 1,617 kPa to 2,450 kPa. Cooling COP had the trend that the higher the ground temperature at 1.75 m went, the lower the COP went. The COP was 2.7 at ground temperature at 1.75 m depth of $25.5^{\circ}C$ and 2.0 at the temperature of $33.5^{\circ}C$ and the heat extraction rate from the greenhouse were 28.8 kW, 26.5 kW respectively at the same ground temperature range. 8 hours after the heat pump was operated, the temperature of ground at 60 cm and 150 cm depth buried a geothermal heat exchanger rose $14.3^{\circ}C$, $15.3^{\circ}C$ respectively, but the temperature of ground at the same depth not buried rose $2.4^{\circ}C$, $4.3^{\circ}C$ respectively. The temperature of heat transfer medium fluid fell $7.5^{\circ}C$ after the fluid passed through geothermal heat exchanger and the fluid rejected average 46 kW to the 1.5 m depth ground. It analyzed the geothermal heat exchanger rejected average 36.8 W/m of the geothermal heat exchanger. Fan coil units in the greenhouse extracted average 28.2 kW from the greenhouse air and the temperature of heat transfer medium fluid rose $4.2^{\circ}C$after the fluid passing through fan coil units. It was analyzed the accumulation energy of thermal storage thank was 321 MJ in 3 hours and the rejection energy of the tank was 313 MJ in 4 hours.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.112-117
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• 2004

Volatile organic compounds (VOCs) are low calorific value gases (LCVG) emitted from chemical processes such as painting booth, dye works and drying processes etc. Characteristics of VOCs are low calorific values less than 150kcal/㎥, high activation energy for ignition and low energy output. These characteristics usually make combustion unstable and its treatment processes needs high-energy consumption. The cyclone combustion system is suitable for LCVG burning because it can recirculate energy through a high swirling flow to supply the activation energy for ignition, increases energy density In make a combustion temperature higher than usual swirl combustor and also increases mixing intensity. This research was conducted to develop optimized cyclone combustion system for thermal oxidation of VOCs. This research was executed to establish the effect of swirl number with respect to the combustion temperature and composition of exhausted gas in the specific combustor design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.88-98
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• 2016

The Korean summer is hot and humid, and air-conditioners consume considerable amounts of electricity. In such cases, the simultaneous use of indirect evaporative coolers may help reduce the sensible heat and save electricity. In this study, heat transfer and pressure drop characteristics of indirect or regenerative evaporative coolers made from plastic/paper are investigated. The results showed that heat and mass transfer model based on the ${\epsilon}-NTU$ method predicted the indirect evaporation efficiencies, cooling capacities and pressure drops adequately. Both for indirect or regenerative evaporative cooler, the indirect evaporation efficiency increased with increasing dry channel inlet temperature or relative humidity. The indirect evaporation efficiency of the regenerative evaporative cooler was larger than that of the indirect evaporative cooler.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1711-1713
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• 2005

최근 고유가 시대에 따른 대체 에너지기술 분야에 대한 관심과 함께 저전력 소비형 전자기기의 동력원으로서 열전발전기술이 주목받고 있다. 열전발전 기술을 이용하여 산업폐열원 등에서 전력을 생산하기 위해서는 폐열원의 열적 분포특성이 우선적으로 검토, 평가되어야 한다. 그 이유는 일반적 산업폐열원의 경우 발전소자가 설치될 열원에서의 열 분포가 실험실 조건에서와 같이 일정면적에서의 균일 열량조건을 만족시키기는 어렵고 국부적 불균일 열 분포를 나타낼 가능성이 매우 높기 때문으로, 이같은 불균일 열원특성은 열전모듈의 직렬연결을 기본으로 하고 있는 열전 발전시스템의 발전능에 직접적 영향을 미치게 되기 때문이다. 따라서 불균일 열원특성에 따른 열전 발전능의 평가는 열전발전기 전체의 발전능을 평가하는 매우 중요한 인자이다. 본 연구에서는 Bi-Te계 열전발전모듈을 이용하여 열편차 조건에서의 열분포 특성 및 열전달 특성변화를 조사하고 이것에 따른 단위발전소자의 발전특성 변화를 규명 하고자 하였다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.8
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• pp.1094-1099
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• 2012

This study investigated the effect of a long-term high-fat diet on energy metabolic substrate utilization in resting rats in order to revalue source fat energy efficiency during a high-fat diet and its effect on energy expenditure and body fat accumulation. Sprague-Dawley male rats at 4 weeks of age were bought from Orient Bio Con. The rats were divided into a control (CON) group and a high-fat diet (HF) group. Rats ate a high-fat diet (w/w 40%, kcal/kcal 64.9%) ad libitum for 5 weeks. Food intake and body weight were measured every day at 09:00 throughout the experimental period. Energy expenditure was measured using an animal energy metabolism chamber after 4 weeks. The final body weight did not change between the CON and HF groups, but caloric intake was significantly higher in the HF group than in the CON group (p<0.05). There was no difference between the groups in oxygen uptake, however carbon dioxide production was significantly higher in the HF group. Also, the respiratory exchange ratio was higher in the HF group. Carbohydrate oxidation was lower in the HF group than in the CON group, but fat oxidation in the HF group was greater. These results mean that energy substrate oxidation at rest is affected by diet composition, especially dietary fat content. Abdominal fat fad weights were significantly higher by 33% in the HF group than in the CON group even though the calorie intake in the HF group was higher by 6%. These results suggested that the dietary fat calorie value might have a higher Atwater value of 9 kcal/g, which mean that dietary fat calorie values could be reconsidered in body weight control scenarios such as which the obese or weight class athletes.

• The Korean Journal of Food And Nutrition
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• v.11 no.2
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• pp.185-191
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• 1998

This study was performed to investigate the nutrition status by weight loss(diet) of 287 female college students, focus on questionnaire about diet survey. The subjects mainly had irregularly one or two meal per a day so food behavior was not good. Over half of subjects had a tendency to overestimate body shape of self. The desired weight(46.95$\pm$0.39kg) was significant lower than real weight(50.32$\pm$0.9)(p=0.0114). The time when diet is first tried was mainly after high school(94.51%). Mean weight loss was 1~4kg but most of subjects didn't maintain the lost weight. The diet approach method tried was sequently the fasting 1 meal or the more in a day(23.61%), exercise(21.92%), restricting calories(15.85%) etc. The source of diet was orderly newspaper or magazine(30.86%), friends or relatives or family(28.86%) etc. The group who recognized the self body shape was normal or a little fat had higher self notion of health than other groups.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.2
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• pp.350-356
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• 2001

The purpose of this study is to verify the relation among vegetarian diet, physical activity and the risk factors of cardiovascular disease. Two hundred and forty five buddhist nuns (age : 23~79 yrs) were selected as vegetarians. For control subjects, 235 healthy female adults (age : 23~79 yrs) were selected. Study period was from October 1996 to February 1997. The contents are consist of food consumption survey, anthropometric measurement, amount of energy expenditure, physical activity and clinical examination. Results were summarized as follows : The average ages of vegetarians were $44.2{\pm}17.3\;yrs$ and those of non-vegetarians were $40.5{\pm}18.4\;yrs$. Average body mass indices (BMI) of vegetarians and non-vegetarians were $22.5{\pm}2.7\;and\;21.1{\pm}2.5$, WHRs were $0.9{\pm}0.1\;and\;0.8{\pm}0.1$, and the average duration of vegetarian diet of the vegetarians was 13.1{\pm}12.9 years. All the nutrient intakes of both groups were over RDA's except calcium and vitamin A intakes of non-vegetarians that were below RDA's Fiber and vitamin C intakes of the vegetarians were significantly higher than those of non-vegetarians (p<0.01). Average energy intakes of vegetarians and non-vegetarians were $2177.1{\pm}420.6\;kcal/day\;and\;2103.2{\pm}534.9\;kcal/day$, total daily energy expenditure were $1789.9{\pm}325.8\;kcal/day\;and\;1703.8{\pm}344.8\;kcal/day$, those by physical activity were $507.8{\pm}360.9\;kcal/day\;and\;400.0{\pm}247.8\;kcal/day$. Serum lipid level, blood sugar, systolic blood pressure of vegetarians were significantly lower than those of non-vegetarians, but ratio of HDL-cholesterol/total-cholesterol was higher than those of non-vegetarians. Levels of total serum cholesterol of vegetarians and non-vegetarians were 161.4{\pm}33.3 mg/dL and 189.6{\pm}33.6mg/dL, HDL-cholesterol were $48.2{\pm}11.4\;mg/dL\;and\;50.8{\pm}12.2\;mg/dL$, LDL-cholesterol were $86.6{\pm}26.9\;mg/dL\;and\;111.1{\pm}17.0\;mg/dL$, atherogenic indice(AI) were $2.4{\pm}0.6\;and\;2.9{\pm}0.7$, fasting blood sugar were $90.8{\pm}14.3\;mg/dL\;and\;103.6{\pm}24.6\;mg/dL$, systolic blood pressure were $107.5{\pm}14.9\;mmHg\;and\;119.3{\pm}15.3\;mmHg$. Energy expenditure by physical activity was negatively correlated with levels of serum total-cholesterol and LDL-cholesterol and atherogenic indice(AI). Therefore, physical activity and vegetarian diet effectively helped reduce blood lipids related to cardiovascular disease.