• 대한영양사협회학술지
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• 제22권2호
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• pp.131-142
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• 2016

The purpose of this study was to assess the physical activity and energy balance of weekdays and weekend in male high school students. Fifty healthy male high school students participated in this study. Anthropometric data were collected. Physical activity level (PAL) and energy intake for weekdays and weekend were calculated from a physical activity diary and food diary using the 24-hour recall method and interview. The resting metabolic rate (RMR) and estimated energy requirement (EER) were calculated from the prediction equations suggested in 2015 KDRIs. Total energy expenditure (TEE) was calculated by multiplying RMR by PAL. Mean age of subjects was $15.9{\pm}0.33years$. The daily pedometer counts were significantly higher in the weekdays (12,837 steps) than in weekend (6,661 steps) (P<0.001). The PAL of the weekdays ($1.63{\pm}0.17$) was significantly higher than that ($1.37{\pm}0.26$) of the weekend (P<0.001). PAL was significantly correlated with pedometer counts on the weekdays (r=0.495) and weekend (r=0.686). The total energy intakes ($2,847.2{\pm}681.5kcal$) and TEE ($3,046.3{\pm}437.3kcal$) of weekdays were significantly higher than those of the weekend. The results of this study would be useful to develop nutrition and exercise programs for male high school students on weekdays and weekend, respectively.

• Journal of Electrochemical Science and Technology
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• 제10권3호
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• pp.302-312
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• 2019

The voltage produced from the salinity gradient in reverse electrodialysis (RED) increases proportionally with the number of cell pairs of alternating cation and anion exchange membranes. Large-scale RED systems consisting of hundreds of cell pairs exhibit high voltage of more than 10 V, which is sufficient to utilize water electrolysis as the electrode reaction even though there is no specific strategy for minimizing the overpotential of water electrolysis. Moreover, hydrogen gas can be simultaneously obtained as surplus energy from the electrochemical reduction of water at the cathode if the RED system is equipped with proper venting and collecting facilities. Therefore, RED-driven water electrolysis system can be a promising solution not only for sustainable electric power but also for eco-friendly hydrogen production with high purity without $CO_2$ emission. The RED system in this study includes a high membrane voltage from more than 50 cells, neutral-pH water as the electrolyte, and an artificial NaCl solution as the feed water, which are more universal, economical, and eco-friendly conditions than previous studies on RED with hydrogen production. We measure the amount of hydrogen produced at maximum power of the RED system using a batch-type electrode chamber with a gas bag and evaluate the interrelation between the electric power and hydrogen energy with varied cell pairs. A hydrogen production rate of $1.1{\times}10^{-4}mol\;cm^{-2}h^{-1}$ is obtained, which is larger than previously reported values for RED system with simultaneous hydrogen production.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제42권
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• pp.22.1-22.6
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• 2020

Introduction: Facial fractures (FFs) occur after high- and low-energy trauma; differences in associated injuries and outcomes have not been well articulated. Objective: To compare the epidemiology, management, and outcomes of patients suffering FFs from high-energy and low-energy mechanisms. Methods: We conducted a 6-year retrospective local trauma registry analysis of adults aged 18-55 years old that suffered a FF treated at the Santa Barbara Cottage Hospital. Fracture patterns, concomitant injuries, procedures, and outcomes were compared between patients that suffered a high-energy mechanism (HEM: motor vehicle crash, bicycle crash, auto versus pedestrian, falls from height > 20 feet) and those that suffered a low-energy mechanism (LEM: assault, ground-level falls) of injury. Results: FFs occurred in 123 patients, 25 from an HEM and 98 from an LEM. Rates of Le Fort (HEM 12% vs. LEM 3%, P = 0.10), mandible (HEM 20% vs. LEM 38%, P = 0.11), midface (HEM 84% vs. LEM 67%, P = 0.14), and upper face (HEM 24% vs. LEM 13%, P = 0.217) fractures did not significantly differ between the HEM and LEM groups, nor did facial operative rates (HEM 28% vs. LEM 40%, P = 0.36). FFs after an HEM event were associated with increased Injury Severity Scores (HEM 16.8 vs. LEM 7.5, P <0.001), ICU admittance (HEM 60% vs. LEM 13.3%, P <0.001), intracranial hemorrhage (ICH) (HEM 52% vs. LEM 15%, P <0.001), cervical spine fractures (HEM 12% vs. LEM 0%, P = 0.008), truncal/lower extremity injuries (HEM 60% vs. LEM 6%, P <0.001), neurosurgical procedures for the management of ICH (HEM 54% vs. LEM 36%, P = 0.003), and decreased Glasgow Coma Score on arrival (HEM 11.7 vs. LEM 14.2, P <0.001). Conclusion: FFs after HEM events were associated with severe and multifocal injuries. FFs after LEM events were associated with ICH, concussions, and cervical spine fractures. Mechanism-based screening strategies will allow for the appropriate detection and management of injuries that occur concomitant to FFs. Type of study: Retrospective cohort study. Level of evidence: Level III.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.534-538
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• 2001

Energy storage devices with high energy density as well as high power density are expected to be developed from the point of view of compensation of fluctuating load and generated power by distributed generations such as wind turbines, photovoltaic cells and so on. SMES (Superconducting Magnetic Energy Storage) has higher power density than other energy storage methods, and secondary batteries have higher energy density than SMES. The hybrid energy storage device using SMES and secondary batteries is proposed as the energy storage method with higher power and energy density, the sharing method of power reference value for each storage device, simulation and experimental results are presented.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 추계학술대회 논문집
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• pp.273-277
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• 2009

This paper presents a basic energy performance data of micro gas turbine, Renewable Energy(BIPV and Solar Collector System, geothermal system) and a hybrid energy system(geothermal system and microturbine) installed in Hospital Building. The efficiency of solar collector and BIPV system was 30%, 10% individually, and lower than micro gas turbines. Micro gas turbines are small gas turbines that bum gaseous and liquid fuels to produce a high-energy exhaust gas and to generate the electrical power. Recently, the size range for micro gas turbines is form 30 to 500kW and power-only generation or in combined heat and power(CHP) systems. Finally, in energy performance aspect, Micro gas turbine system and hybrid energy system were high-efficiency system in hospital building. Hybrid energy system also give us a powerful alternative energy system economically.

• 전기학회논문지
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• 제57권10호
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• pp.1790-1795
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• 2008

Energy scavenging is a technique that converts ambient energy, for example, vibration and light, to electrical energy in order to supply power to low power electronic devices such as ubiquitous sensors. In this paper, we propose an optimal operation condition of power delivery circuit and design strategy for energy scavenging system in which the generated power is order of microwatt and, consequently, efficient handling of power is critical. We also propose that high data transmission rate is more realistic optimal design objective rather than high energy efficiency. It is shown that disconnection of load from the storage capacitor right after data transmission reduces energy wasting and that optimal value of storage capacitor can be determined at this condition. The feasibility of our propose is proved by experiments and we believe that the proposed design strategy will promote the application of piezoelectric micropower generator to the ubiquitous sensor networks.

• 한국지열·수열에너지학회논문집
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• 제14권1호
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• pp.30-35
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• 2018

In this study, the energy commissioning was conducted for high-rise buildings(manual control). First of all, we conducted monitoring the energy use of buildings (electricity, heating, etc.), a commissioning improvement (automatic control) was proposed for each system. In addition, energy simulation was conducted to predict the effectiveness of the reform measures. As a result, terminal units control the greatest energy saving effect, If we applied all the improvements, we could save about 20% less than traditional energy usage, and it turned out that $CO_2$ emissions were reduced by about 19% when converted to $CO_2$.

• Journal of Electrochemical Science and Technology
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• 제3권1호
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• pp.14-23
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• 2012

Increasing demand of energy, the depletion of fossil fuel reserves, energy security and the climate change have forced us to look upon alternate energy resources. For today's electric vehicles that run on lithium-ion batteries, one of the biggest downsides is the limited range between recharging. Over the past several years, researchers have been working on lithium-air battery. These batteries could significantly increase the range of electric vehicles due to their high energy density, which could theoretically be equal to the energy density of gasoline. Li-air batteries are potentially viable ultra-high energy density chemical power sources, which could potentially offer specific energies up to 3000 $Whkg^{-1}$ being rechargeable. This paper provides a review on Lithium air battery as alternate energy resource for the future.

• Asian-Australasian Journal of Animal Sciences
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• 제17권7호
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• pp.947-953
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• 2004

The present research was designed to evaluate the effects of pre and post-partum energy level and feeding pattern on the performance of crossbred dairy cows and their calves under farm conditions. A total of 16 crossbred dairy cows were divided into two equal groups on the basis of their body weight and milk production. One group was given 30% less and the another was given 30% more energy than MAFF's (1984) recommendation. After calving all cows were given same ad.libitum diet to assess the effects of feeding during pregnancy on their performance. It was observed that just before calving cows on low energy group gained less (p<0.05) weight than that of the cows on high energy group (12.9$\pm$11.71 vs. 42.25$\pm$12.74 kg/cow. Birth weight of calves of low energy group was lower (p<0.05) than that of the calves of high energy group (17.87$\pm$1.78 vs. 20.73$\pm$2.24 kg/calf). Cows that were on low pre-calving dietary energy level produced less milk during lactation than the cows of high energy pre-calving group (3.45$\pm$0.75 vs. 4.27$\pm$0.79 lit./cow). No significant difference was noticed on calf growth rate and reproductive parameters of cow. Energy level that was 30 % less than MAFF's (1984) recommendation was found to be very low and not suitable for our crossbred cows during their last three months of pregnancy.

• 한국학교보건학회지
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• 제30권1호
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• pp.48-58
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• 2017

Purpose: The purpose of this study was to identify the factors associated with energy drink consumption in Korean high school students. Methods: This cross sectional study used the secondary data from the 2015 Adolescent Health Behavior Online Survey. A total of 33,744 high school students were included in the study. Energy drink consumption was measured by asking how often they consumed energy drink during the previous week. Associated factors were categorized into socio-demographic characteristics, psychological characteristics, and health related behavioral characteristics. Complex samples logistic regression was used to analyze the influence of associated factors on energy drink consumption. Results: For socio-demographic characteristics, adolescent boys were likely to consume more energy drink than adolescent girls (Adjusted Odds Ratio [AOR]: 1.351, 95% Confidence Interval [CI]: 1.209~1.510). For psychological characteristics, depressed adolescents were likely to consume more energy drink than their counterparts (AOR: 1.697, 95% CI: 1.537~1.874). For health related behavioral characteristics, cigarette smoking (AOR: 1.336, 95% CI: 1.168~1.528), alcohol drinking (AOR: 1.126, 95% CI: 1.012~1.254), soda drink consumption (AOR: 1.800, 95% CI: 1.565~2.071), sweet drink consumption (AOR: 1.715, 95% CI: 1.431~2.054), and insufficient sleep time a day (AOR: 1.307, 95% CI: 1.197~1.427) were associated with energy drink consumption. Conclusions: In conclusion, energy drink consumption in Korean high school students were associated with such factors as psychological factors (depression) and health related behavioral characteristics (smoking, alcohol, sleep, soda and sweet drink). Thus, intervention programs in schools and communities should focus on these psychological and health related behavioral characteristics.