• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4625-4641
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• 2016

The performances of two commonly used feature detectors for wireless energy-harvesting cognitive radio systems are compared with the energy detector under energy causality and collision constraints. The optimal sensing duration is obtained by analyzing the effect of the detection threshold on the average throughput and collision probability. Numerical examples show that the covariance detector has the optimal sensing duration depending on an appropriate choice of the detection threshold, but no optimal sensing duration exists for the ratio of average energy to minimum eigenvalue detector.

• Journal of KIISE:Information Networking
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• v.33 no.2
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• pp.165-174
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• 2006

Data dissemination using either flooding or legacy ad-hoc routing protocol is not realistic approach in the wireless sensor networks, which are composed of sensor nodes with very weak computing power, small memory and limited battery. In this paper, we propose the ELF(Energy-efficient Localized Flooding) protocol. The ELF is energy-efficient data dissemination protocol for wireless sensor networks. In the ELF protocol, there are two data delivery phases between fixed source and mobile sink node. The first phase, before the tracking zone, sensing data are forwarded by unicasting. After that, within the tracking zone, sensing data are delivered by localized flooding. Namely, the ELF Properly combines advantages from both unicasting and flooding. According to evaluation results by simulation, the proposed ELF protocol maintains very high data delivery ratio with using a little energy. Also, the property of average delay is better than others. From our research results, the ELF is very effective data dissemination protocol for wireless sensor networks.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.220-225
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• 2011

Based on the supply status statistics of new renewable energy according to public obligation system, current status of overall application centered on solar heat, solar ray, and geothermal heat as energy sources that can be applied to buildings may be analyzed as follows. (1) After the public obligation system, the investment costs on the total construction costs by years were between 5.21% and 7.12%: they were 7.12% in 2004, where the system was initially implemented; and they were gradually declined from 2005 to 2011, 5.76% in average. The ratio of equipment investment per energy sources in the total construction costs was 5.9%, which was slightly more than the obliged ratio. The order of investment costs per energy source was solar ray, geothermal heat, and solar heat. (2) Among the 1,433 sites in the plan of new renewable energy installation based on the public obligation system, "for cultural & social use" was most in target institution, and facilities for education & research was most in use classification, followed by public working, culture & rally, and sports. The number of facilities applied according to the case for planning installation per use classification of the target institution was between 1.1 and 1.5, or 1.4 in average of energy source. Conclusively, the authors of this study investigated overall current status of new renewable energy supply from the analysis of statistic data, and it may be needed of further supplementation of various examinations by visiting investigation and interviews with practitioners based on classification of use of target institutions.

• Journal of the Korean Solar Energy Society
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• v.40 no.1
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• pp.35-47
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• 2020

Due to the large window area, the lighting environment of the educational space between the window and deep part of the room is not uniformly illuminated, and the phenomenon of glare is severe. For this reason, the daylight performance of DSC-BIPV windows was analyzed in order to improve the natural lighting in the educational sector. The method derives the correlation with natural lighting by measurement and simulation. Dynamic simulation confirmed that the average illuminance of the target space was higher at later than the early afternoon. The performance of natural lighting at 40% and 30% transmission of DSC has the effect of significantly reducing the amount of excess light in existing windows. Nevertheless, the actual average illuminance in all seasons corresponds to the standard illuminance of the educational facility, 300 Lux. In addition, the uniformity is also seen through the skylight illuminance ratio.

• Korean Journal of Community Nutrition
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• v.18 no.4
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• pp.333-343
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• 2013

It is important to prepare and execute the menu plan for proper and balanced intake of nutrients in the adolescence. This study investigated the new approach for planning menu by ordinary meal pattern based on cooked foods groups. The amounts of cooked foods in the menu plan assumed to be single serving size. The middle school second graders participated for the study. A total of 313 questionnaires were analyzed using CAN-pro 3.0 and SPSS WIN 12.0 program. The average content of energy in the menu plan was 2,453 kcal, the average ratios of energy contribution by carbohydrate, protein and fat were 54.3%, 17.9%, 27.8%, respectively. A total of 56.9% menu plans (94.9% of male and 8.7% of female students') were below the lowest limit of optimum carbohydrate energy ratio of 55%. A total of 29.1% menu plans (33.1% of male and 23.9% of female students') were exceed the highest limit of optimum fat energy ratio of 30%. The NAR of minerals and vitamins were all 1.0 except for calcium (0.92) and folate (0.88). When INQ of the individual cooked food groups were calculated, kimch was the highest in all minerals and vitamins examined, suggesting that kimch may be the best source for all minerals and vitamins, including calcium and folate with the minimum change in energy content. In conclusion, the menu plan by ordinary meal pattern in this study was low in carbohydrate, high in fat, and contained enough minerals and vitamins except for calcium and folate for middle school students.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.319-321
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• 2004

The average glandular dose (AGD) is determined by the breast entrance skin exposure, x-ray tube target material, beam quality (half-value layer), breast thickness, and breast composition. Almost breast cancer always arises in glandular breast tissue. As a result, the average radiation absorbed dose to glandular tissue is the preferred measure of the radiation risk associated with mammography. If the normalized average glandular dose is known, the average glandular dose can be computed from the product of the normalized average glandular dose and breast entrance skin exposure. In this study, AGD was calculated by the breast thickness and various x-ray energy (HVL) in 50% glandular 50% adipose breast by Mo.-Rh. assembly. AGD is 84 mrad in compressed 5 cm breast. These results show that as increasing the breast thickness, dose also increases. But as increasing the x-ray tube voltage, dose decreases because of high penetrating ratio through the object. But high tube voltage is reducing the subject contrast. From this result, we have to consider the trade-off between subject contrast of image and dose to the patient and choose proper x-ray energy range.

• Korean Journal of Community Nutrition
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• v.6 no.3
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• pp.306-316
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• 2001

This study investigated the correlations between nutrient intake and dietary attitudes in Korean school dietitians. A total of 493 school dietitians working in the Kangwon and Kyungnam areas participated in this study. The subjects were classified as the good group(33.5%), fair group(36.9%) and bad group(29.6%) based on dietary attitude score. The results were as follows. The average intake of energy, calcium, and iron were lower than the Korean RDA and average CPF ratio of energy intake was 64 : 17 : 19. The percent RDAs of nutrient intake of energy, calcium, iron and vitamin B$_1$were lower in the bad group than those in the fair group and good groups(p < 0.001). The mean adequacy ratio(MAR), an index of overall dietary quality, were different among the three groups(p < 0.001), the highest was 0.96 in the good group, the lowest was 0.88 in the bad group. The index of nutritional quality(INQ) was significantly higher in the good group than the other groups. The nutrient intakes were positively correlated with dietary attitudes(p < 0.01). The nutrient intakes, INQ, NAR and MAR were significantly increased as the dietary attitude score increased.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_2
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• pp.73-77
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• 2001

The disposal of sewage sludge using landfills and ocean dumping is no longer a viable option due to land scarcity and increasingly stringent environmental control regulations. As such, various efforts have been made to develop new sewage sludge recycling technologies. This work investigates the fundamental physical and chemical characteristics of rural type sewage sludge from Chungnam province in South Korea. The average moisture content, ignition loss, elementary analysis, and average heating value of the sewage sludge samples were examined. The average moisture content of the dewatered sludge was about 80%, while the organic matter was about 50% of the total solid sludge weight. The average heating value of a sewage sludge and petroleum coke waste mixture(1:1 weight ratio) was about 5,000 ㎉/kg, thereby indicating a high potential for energy recycling.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.62.1-62.1
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• 2011

The structural, optical, and electrical properties of Ga-doped ZnO (GZO) thin films on glass substrates grown by radio-frequency(RF) magnetron sputtering were investigated. The flow ratio of Ar was varied as a deposition parameter for growing high-quality GZO thin films. The structural properties and surface morphologies of GZO were characterized by the X-ray diffraction. To analyze the optical properties of GZO, the optical absorbance was measured in the wavelength range of 300-1100 nm by using UV-VIS spectrophotometer. The optical transmittance, absorption coefficient, and optical bandgap energy of GZO thin films were calculated from the measured data. The crystallinity of GZO thin films is improved and the bandgap energy increases from 3.08 to 3.23eV with the increasing Ar flow ratio from 10 to 100 sccm. The average transmittance of the films is over 88% in the visible range. The lowest resistivity of the GZO is $6.215{\times}10^{-4}{\Omega}{\cdot}cm$ and the hall mobility increases with the increasing Ar flow ratio. We can optimize the characteristics of GZO as a transparent electrode for thin film solar cells by controlling Ar flow ratio during deposition process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.4
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• pp.775-784
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• 1998

This study was conduced to investigate the seasonal variation of dietary intake and quality obtained by 24 hour recall method in Korean adults living in rural area. The mean daily intakes of 4 seasons were 1,692kcal for energy, 63g(14.8% of energy) for protein, 30g(15.7% of energy) for fat, 257g(60.7% of energy) for carbohydrate. Mean daily intakes were significantly highest in winter for most of the nutrients, and lower in summer for energy, fat, calcium, iron. Mena adequacy ratio(MAR), an index of overall nutritional quality was 0.65 in winter, 0.67 in spring, 0.65 in summer and 0.72 in autumn and nutrient adequacy ratio(NAR) was significantly different fro vitamin C agmong different seasons. Subjects consumed usually 15.3 different foods in winter, 14.5 in summer, 13.9 in spring and 13.7 in autumn. The number of food consumed was positively correlated with intake of most nutrients, especially in autumn. For variety among the five major food groups(grain, meat, dairy, fruit, vegetable) with a dietary diversity scores(DDS) calculated, the average socre of DDS was 3 in all seasons and omitted food groups were usually dariy and fruit. In conclusion, dietary intake and quality of Korean adults were different according to seasons.