• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.262-268
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• 2012

In the recent research technical solutions have been studied to integrate renewable energy into unmanned aerial vehicles to use it as the main power source. As the weight of the aerial vehicle body is essential for its performance, we consider to use light-weight solar cell technology. Furthermore fuel cells are also integrated create a highly energy-efficient aerial robot. In this paper, construction concept and software design of the tilt-rotor aerial vehicle GAORI is introduced which uses solar cells and fuel cells as power source. The future work direction and prognosis are discussed.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.85-88
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• 2002

We have implemented a system of falling weight impact tester. Absorbed energy of orthotropic composites with using T300 fiber, which are composed of the same fiber and stacking number is higher than that of quasi-isotropic specimen over impact energy 7J, but in case of using T700 fiber, much difference does not show. Also, absorbed energy of orthotropic composites with using T300 fiber, which are composed of stacking number and orientation became more than that of T700 fiber specimen; however great change doesn't show in case of quasi-isotropic specimens. Delamination area of impacted specimens was measured with ultrasonic C-scanner to find correlation between impact energy and delamination area. Delamination area and frequency responses was evaluated between impacted and unimpacted specimens. There is a strong correlation between frequency responses and impact-induced delamination. The presence and scale of damages have been investigated based on the variations of frequency responses.

• Journal of Energy Engineering
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• v.6 no.2
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• pp.198-202
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• 1997

The oxidation behavior of UO$_2$pellets was studied using a thermogravimetric analyzer and an XRD in the temperature range of 300 to 550$^{\circ}C$ in air. From XRD studies it is found that UO$_2$is converted to U$_3$O$\_$8/ and the weight gains of UO$_2$specimen are characterized by S-shape curves. After complete oxidation the specimens broke into fine powder and the average weight gain was about 3.93 wt%. The activation energy of 50% conversion of UO$_2$to U$_3$O$\_$8/ is 81.6 kJ/mol and the oxidation rate per unit time was found to be as follows dw/dt=6.54${\times}$10$\^$6/ e (equation omitted), wt%/h : at 50% conversion of UO$_2$into U$_3$O$\_$8/ where w, t and T were wt% gain, conversion time and temperature, respectively.

• Journal of Electrochemical Science and Technology
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• v.7 no.1
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• pp.41-51
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• 2016

In the stratosphere, the air is stable and a photovoltaic (PV) system can produce more solar energy compared to in the atmosphere. If unmanned aerial vehicles (UAVs) fly in the stratosphere, the flight stability and efficiency of the mission are improved. On the other hand, the weakened lift force of the UAV due to the rarefied atmosphere can require more power for lift according to the weight and/or wing area of the UAV. To solve this problem, it is necessary to minimize the weight of the aircraft and improve the performance of the power system. A regenerative fuel cell (RFC) consisting of a fuel cell (FC) and water electrolysis (WE) combined PV power system has been investigated as a good alterative because of its higher specific energy. The WE system produces hydrogen and oxygen, providing extra energy beyond the energy generated by the PV system in the daytime, and then saves the gases in tanks. The FC system supplies the required power to the UAV at night, so the additional fuel supply to the UAV is not needed anymore. The specific energy of RFC systems is higher than that of Li-ion battery systems, so they have less weight than batteries that supply the same energy to the UAV. In this paper, for a stratospheric long-endurance hybrid UAV based on an RFC system, three major design factors (UAV weight, wing area and performance of WE) affecting the ability of long-term flight were determined and a simulation-based feasibility study was performed. The effects of the three design factors were analyzed as the flight time increased, and acceptable values of the factors for long endurance were found. As a result, the long-endurance of the target UAV was possible when the values were under 350 kg, above 150 m² and under 80 kWh/kg H₂.

• New & Renewable Energy
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• v.7 no.1
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• pp.29-35
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• 2011

The waste treatment fee and energy production effect of Wonju city RDF plant, the first RDF manufacturing plant in Korea, were investigated in the study. All plant operation data, like total weight of received wastes, produced RDF and separated rejects in processes were fully recorded for mass balance calculation of the plant in 2009. Also all consumed oil and electricity were recorded for energy balance calculation. The results showed that the waste treatment fee not including the RDF sales price of 25,000 won/ton-RDF was 116,573 won/ton-MSW and it went down to 105,298 won when included the RDF price. Produced RDF was 40.2% of total received waste in weight. Three components analysis by mass balance calculation of total received waste showed that Wonju city's MSW was 32.4% of combustible, 37.5% of water and 30.1% of incombustible respectively. Energy effect was found that total amount of produced energy was about 4 times more than that of consumed energy.

• Nutritional Sciences
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• v.8 no.2
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• pp.118-124
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• 2005

To examine the eating attitudes, weight concerns, dietary intake, and menstrual function of Korean female elite athletes, 109 subjects in seven sports disciplines (rhythmic gymnastics, synchronized swimming, badminton, volleyball, Taekwondo, field hockey, and soccer) responded to a questionnaire consisted of three parts; eating attitudes and behavior(Eating Attitude Test-26; EAT26), body weight perception (Body Dissatisfaction Index: BDI) and weight control behavior, and menstrual history and status. They also recorded three-day dietary intake. Body weight (43.6$\pm$4.3 kg) and body mass index (16.7$\pm$1.4 kg/$m^2$) in rhythmic gymnasts were lower than those in other athletes (P<0.05). EAT26 scores were not different among sport events (12.3$\pm$6.5 total), however, eating disturbances (EAT26 score$\geq$20) were highly prevalent in aesthetic athletes ($30\%$) than in others ($5\%$). More than half of the athletes perceived themselves overweight and four fifth of the athletes desired to reduce weight about 4.4 kg. The gymnasts consumed the lowest caloric intake (1028:t371) while the volleyball players did the highest (2995$\pm$342 kcal/d) (P<0.05). The BDI score was not different among sport events. Three fourth of the athletes experienced weight control, and the most frequently used weight reduction method was exercise followed by using robber suits, diet, and sauna. About $40\%$ of the subjects reported irregular menstrual cycles, but menstrual dysfunction ($\leq$6 menses/yr) was only $5\%$. Generally, the Korean female elite athletes desired to reduce weight from their current body weight. No differences in eating attitude and body dissatisfaction were noticed among athletic disciplines. However, eating disturbances were highly prevalent in aesthetic athletes who also reported much less energy intake than the recommend daily energy intake. It appeared that weight reduction methods were not properly practiced in these population. Menstrual dysfunction was minimally reported.

• Journal of the Korean Dietetic Association
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• v.23 no.1
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• pp.78-93
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• 2017

The purposes of this study were to assess energy expenditure of eight walking activities in normal weight and overweight or obese high school students and to evaluate the accuracy of two accelerometers worn on the ankle and waist. Thirty-five (male 17, female 18) healthy high school students participated in this study. They were classified into normal weight (n=21) and overweight or obese (n=14) groups. The subjects completed five treadmill walking activities (TW2.4, TW3.2, TW4.0, TW4.8, TW5.6), followed by three self-selected hallway walking activities (walk as if walking and talking with a friend: HWL, walk as if hurrying across the street at a cross-walk: HWB, walk as fast as you can but do not run: HWF). Energy expenditure and metabolic equivalents (METs) were measured using a portable indirect calorimeter, and predicted energy expenditures and METs were derived from two accelerometers placed on the ankle and waist. Measured energy expenditures per body weight (kg) of eight walking activities were significantly higher in the normal weight group than in the obese group and significantly higher in female than male. The ankle accelerometer overestimated energy expenditures and METs (bias 49.4~105.5%), whereas the waist accelerometer underestimated energy expenditures and METs (bias -30.3~-85.8). Except for HWF (fast) activity, METs of seven activities were moderate intensity based on Compendium METs intensity categories. HWF (fast) activity was vigorous intensity. METs from the ankle accelerometer were vigorous intensity except TW2.4 activity (moderate intensity). METs from the waist accelerometer were low intensity (TW2.4, TW3.2, TW4.0, TW4.8, HWL) and moderate intensity (TW5.6, HWB, HWF). Physical activity guidelines were developed based on measured physical activity level of high school students. Further studies should investigate the effects of body composition in larger subjects.

• Nutrition Research and Practice
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• v.10 no.5
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• pp.524-529
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• 2016

BACKGROUND/OBJECTIVES: Use of smaller plates to control food intake is a commonly recommended strategy for restricting energy intake, despite conflicting results. Therefore, the aim of this study was to examine whether or not three different sizes of plates influence energy intake during a multi-itemed buffet meal in normal weight women. SUBJECTS/METHODS: This was a cross-over study conducted on 37 female participants aged 19-25 years with normal BMI levels. Participants were recruited from Hacettepe University and the surrounding community. On experimental days, participants ate a standard breakfast and were then randomly assigned to eat lunch using a small (19 cm), medium (23 cm), or large (28 cm) diameter plate. Visual analogue scale (VAS) scores on sensory and satiety outcomes were measured for all meals. Energy and macronutrient intakes during lunch were recorded. RESULTS: There was no evidence that use of a smaller plate size reduced energy or specific macronutrient intake during the free choice lunch meal. Multiple visits to the serving table were not associated with energy or macronutrient intake. Plate size did not affect VAS scores during the test days. CONCLUSIONS: Plate size did not influence energy intake, meal composition, or palatability in normal weight women during a multi-itemed open buffet lunch. Studies in natural settings at the population level are needed to clarify current outcomes.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.10
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• pp.1516-1521
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• 2008

This study was conducted to investigate the effects of different energy intake on physical and chemical composition in body fractions, growth performance and meat characteristics of finishing barrows and gilts. A total of twenty six crossbred (Landrace$\times$Yorkshire) consisting of 16 barrows and 13 gilts were used in this study. The animals were allocated by sex to two treatments to form a $2\times2$ factorial arrangement. The respective factors were sex (barrow and gilt) and dietary energy intake (1.8 and 3.0 times energy for maintenance). Pigs were kept in individual pens and had ad libitum access to feed and water from the start of the experiment at $52.4{\pm}1.9kg$ until they reached $109.9{\pm}4.4kg$ live weight. The growth performance, physical composition and meat characteristics of finishing pigs were not greatly affected by the sex. However, higher fat tissue weight in the carcass was observed in barrows compared with gilts (p<0.05). Higher proportions of water and protein (p<0.05), and lower lipid proportion (p<0.01) in the empty body and carcass were observed in gilts compared with barrows, while protein proportion in lean tissue was not affected by the sex. In fat tissue, only protein proportion was higher in gilts compared with barrows (p<0.05). Although, growth performance, physical and chemical compositions in body fractions were greatly affected, final body or carcass weight was partly affected by the energy intake In addition, loin characteristics such as shear force and loin eye area were partly influenced by energy intake levels. Therefore, the present results showed that growth performance and meat characteristics were not influenced but chemical body composition was greatly influenced by the sex. Growth performance, physical and chemical compositions in body fractions were greatly affected, whereas meat characteristics were partly affected by the energy intake levels.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.5
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• pp.574-580
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• 2019

Conventional energy efficient routing protocols apply high weight to energy among routing metrics, causing nodes to concentrate on energy efficient paths and quickly exhaust energy on those paths. The unbalanced energy consumption of these wireless sensor networks causes network division and malfunction, and reduces network lifetime. Therefore, in this paper, it proposes a link cost based routing protocol to solve the unbalanced energy consumption of wireless sensor networks. The proposed routing protocol calculates the link cost by applying the weight of the routing metric differently according to the network problem situation and selects the path with the lowest value. As a result of the performance analysis, it confirmed that the proposed routing protocol has 22% longer network life, 2% energy consumption standard deviation and 2% higher data reception rate than the existing AODV protocol.