• The Korean Journal of Food And Nutrition
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• v.20 no.1
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• pp.88-95
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• 2007

The purpose of this study was to investigate the effects of a 12 week weight control program, which included nutrition education and regular physical fitness, on body weight, degree of obesity, BMI, and lowering of blood lipids in 16 obese male elementary school students. Changes in waist and hip circumferences and their ratios were measured at the conclusion of the 12 week program conducted from September 9 to November 25, 2005. Body weight after 12 weeks on the program slightly reduced from 55.4${\pm}$10.9 kg to 54.4${\pm}$9.7 kg. Degree of obesity and BMI decreased from 121.3${\pm}$8.1%, and 25.9${\pm}$3.3 to 120.0${\pm}$8.2% and, 25.6${\pm}$2.7, respectively. Body fat percentage decreased slightly from 38.3${\pm}$4.7% to 37.9${\pm}$5.2%. Waist to hip ratio did not change after 12 weeks. There were slight changes in weight of body fat and lean body mass from 22.12${\pm}$6.53 kg and 34.56${\pm}$4.75 kg to 21.68${\pm}$6.05 kg and 34.70${\pm}$4.54 kg, respectively. Also, after 12 weeks on the weight control program, body, waist, and hip circumferences decreased. However, there were no significant differences among the blood lipid components, including triglycerides, total cholesterol, and HDL-cholesterol. Finally, body weight, degree of obesity, BMI, and body fat showed more significant correlations to waist, hip circumference and their ratio than to blood lipid levels.

• Journal of the Korean Electrochemical Society
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• v.24 no.3
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• pp.65-75
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• 2021

Coin cell is a basic testing platform for battery research, discovering new materials and concepts, and contributing to fundamental research on next-generation batteries. Li metal batteries (LMBs) are promising since a high energy density (~500 Wh kg^-1) is deliverable far beyond Li-ion. However, Li dendrite-triggered volume fluctuation and high surface cause severe deterioration of performance. Given that such drawbacks are strongly dependent on the cell parameters and structure, such as the amount of electrolyte, Li thickness, and internal pressure, reliable Li metal coin cell testing is challenging. For the LMB-specialized coin cell testing platform, this study suggests the optimal coin cell structure that secures performance and reproducibility of LMBs under stringent conditions, such as lean electrolyte, high mass loading of NMC cathode, and thinner Li use. By controlling the cathode/anode (C/A) area ratio closer to 1.0, the inactive space was minimized, mitigating the cell degradation. The quantification and imaging of inner cell pressure elucidated that the uniformity of the pressure is a crucial matter to improving performance reliability. The LMB coin cells exhibit better cycling retention and reproducibility under higher (0.6 MPa → 2.13 MPa) and uniform (standard deviation: 0.43 → 0.16) stack pressure through the changes in internal parts and introducing a flexible polymer (PDMS) film.

• Journal of the Korean Applied Science and Technology
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• v.41 no.3
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• pp.813-824
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• 2024

This study was conducted to evaluate the long-term effects of training on the physical development and exercise performance of adolescent weightlifters, aiming to provide effective training and management strategies for improving competitive performance. In order to achieve the objectives of the study, adolescent weightlifters from middle and high schools in Chungcheongnam-do province [male middle school-aged athletes, n=5; female middle school-aged athletes, n=5; male high school-aged athletes, n=12; female high school-aged athletes, n=8] were examined over approximately 10 months of weightlifting-based training to analyse the changes in body composition, physical fitness (muscular strength, muscular endurance, agility, flexibility, dynamic balance, coordination), and isokinetic muscular function (trunk and lower extremity). As a result, it was found that the physical development of middle and high school-aged athletes underwent physical development primarily characterized by an increase in lean body mass. Additionally, back muscle strength and power, which contribute to rapid and efficient force transmission between the upper and lower body, as well as grip strength necessary for controlling the barbell with a stable grip, are significant factors. These aspects were notably enhanced through specialized training and competitive experience for weightlifting performance at the high school level. On the other hand, changes in factors beyond the primary physical attributes contributing to weightlifting performance were limited, suggesting differences in effectiveness likely stemming from the specific composition of training programs or the athletes' experience and skill levels. Collectively, the findings from this study, which evaluates the physical characteristics and exercise abilities of adolescent weightlifters, are expected to contribute to improved competitive performance of weightlifters.