• 동아시아식생활학회지
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• 제21권5호
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• pp.756-770
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• 2011

This study was conducted on 419 middle school students (214 boys, 205 girls) in order to examine the general aspects, dietary habits, and performance of the school food services available to them in the Chungnam area. The mean age of the subjects was 15.1 years. The average heights and weights were 164.5 cm and 55.6 kg for boys and 158.9 cm and 49.4 kg for girls, respectively. The influence of parents was found to have a significant effect on the students' nutritional knowledge. Exactly 45.1% of subjects said that they needed time for nutritional education, and 54.2% of subjects answered that they have not received any nutritional education. The amount of spending money and expenditures for snacks per month were positively correlated with family income. Breakfast was skipped more than once per week in more than half of all students. Exactly 40.5% of subjects were satisfied with their schools' food services. As food services are more likely to correct unbalanced diets and provide an incentive for change towards better dietary habits, school food services can play a role in correcting unbalanced dietary behaviors.

• 대한지역사회영양학회지
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• 제4권3호
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• pp.345-355
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• 1999

This study was intended to provide basic information for nutrition education and meal planning by evaluating the nutritional status, food habits, and food preference of elementary school children with school lunch program and without school lunch program(lunch box). The subjects of this study consisted of 266 elementary school children aged from 10 to 12(136 male, 130 female) in Ulsan the area. The survey was conducted by questionnaires and data were analyzed by SPSS program. The average body weight was $38.4{\pm}6.9kg$ for boys and $36.8{\pm}7.4kg$ for girls and the average heights was $141.3{\pm}5.6cm$ for boys and $141.2{\pm}5.7cm$ for girls. These values were lower than that of the Korean reference. 56.0% of the subjects skip breakfast 1 to 2 times a week, 58.2% of the subjects had prejudice for special food, such as bean, anchovy, and pork. The food habit scores of the subjects was divided into poor(11.7%), fair(63.5%), and good(24.8%). The average score of girl's was significantly(p<150) higher than that of the boy's. Compare to 1/3 of RDA for children, the average intake of nutrients provided lower amounts of all nutrients. Therefore Calcium and vitamin A intakes were especially lower than the others. Therefore the importance of milk and green vegetables must be emphsized to them through nutrition education. Children preferred ssalbab to jabkogbab and liked beef-based soup, and baechu kimchi. There were significant differences in food habit scores with gender, parent's education, and exercise. The results of this study indicate that nutrition education and menu planning program should be applied to elementary school children who are served by the school lunch program.

• 한국운동역학회지
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• 제26권1호
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• pp.71-82
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• 2016

Objective: The purpose of this study was to investigate kinematic comparisons of Tsukahara vault in gymnastics between a top-level athlete and sublevel collegiate athletes in order to obtain information on key biomechanical points for successful Tsukahara vaults. Methods: An Olympic gold medalist (height, 160 cm; weight, 52 kg; age, 25 years) and five sublevel collegiate gymnasts (height, $168.2{\pm}3.4cm$; weight, $59.6{\pm}3.1kg$; age, $23.2{\pm}1.6years$) participated in this study. They repeatedly performed Tsukahara vaults including one somersault. Fourteen motion-capturing cameras were used to collect the trajectories of 26 body markers during Tsukahara vaults. Event time, displacement and velocity of the center of mass, joint angles, the distance between the two hands on the horse, and averaged horizontal and vertical impact forces were calculated and compared. Results: The top-level athlete showed a larger range of motion (ROM) of the hip and knee joints compared to sublevel collegiate athletes during board contact. During horse contact, the top-level athlete had a narrow distance between the two hands with extended elbows and shoulders in order to produce a strong blocking force from the horse with a shorter contact time. At the moment of horse take-off, reactive hip extension of the top-level athlete enhanced propulsive take-off velocity and hip posture during post-flight phase. Conclusion: Even though a high velocity of the center of mass is important, the posture and interactive action during horse contact is crucial to post-flight performance and the advanced performance of Tsukahara vaults.

• 한국운동역학회지
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• 제26권1호
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• pp.39-50
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• 2016

Objective: The purposes of this study were to compare the kinematics of a two-arm kettlebell swing between experts and beginners and to identify the correct postures and biomechanical key points in an attempt to prevent sports injuries induced by a kettlebell swing. Methods: Four experts (height, $169.7{\pm}1.5cm$; weight, $70.5{\pm}1.8kg$; age, $32.0{\pm}1.0years$) licensed to teach kettlebell exercises and three beginners (height, $173.7{\pm}4.1cm$; weight, $78.3{\pm}3.8kg$; age, $30.0{\pm}1.4years$) with no kettlebell exercise experience participated in this study. Each participant performed 15 repetitions of a two-arm kettlebell swing using a 16-kg weight. Joint angles, angular velocities, and peak angular velocity sequences were calculated and compared between the two groups. Results: Large ranges of motion (ROM) of the pelvic angle and hip joints were detected in the experts, while beginners showed greater ROM of the shoulder joint. Peak angular velocity magnitudes and sequences were significantly different between the two groups. Experts lifted the kettlebell upward using the hip joints, pelvis, and shoulder joints (proximal to distal order) sequentially and lowered it using the reverse order of peak angular velocities from the shoulder to hip joints. Conclusion: Mobility of the pelvic segment and hip joint are required, while stability of the other joints is needed to produce appropriate two-arm kettlebell swings. The activation and coordination of the gluteal and hamstring muscles are key points in kettlebell exercises.

• 한국운동역학회지
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• 제22권4호
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• pp.387-394
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• 2012

The purpose of this study was to compare and analyze the finger pressure and kinematic variables in the forehand hairpin net shot between skilled elite players and less skilled recreational players. Eight elite players(age: $18.1{\pm}0.8yrs$, height: $176.8{\pm}1.5cm$, weight: $640.9{\pm}48.6N$) with minimum of 6 years of experience and eight recreational players(age: $27.9{\pm}1.6yrs$, height: $177.1{\pm}6.1cm$, weight: $820.5{\pm}62.8N$) with less than one year experience were recruited in this study. For each trial being analyzed, four critical instants were identified from the video recordings: Right heel contact1 (E1), Right toe-off (E2), Right heel contact2 (E3), and Shuttlecock Impact (E4). Each hairpin net shot was broken into consecutive phases: E1~E2 (Right Landing Phase: RLP), E2~E3 (Sliding Step Phase: SSP), and E3~E4 (Impact Phase: IP). Temporal parameters, shuttlecock speed, linear and angular kinematics of body segments, and finger pressures were computed for this study. The results showed that The finger pressure of the ring finger and the middle finger for the skilled group during an impact had significantly greater than those of unskilled group. It is possible that all fingers were not used in the same manner when the racket was gripped in forehand hairpin. The result also suggested that the ring finger and the middle finger pushed the racket from top to bottom while having the mid-phalanx and proximal phalanx of index finger as an axis.

• 한국운동역학회지
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• 제23권2호
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• pp.109-116
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• 2013

The purpose of this study was to provide fundamental information for the enhancement of performance through kinematic analysis of cornering according to the radius of curve course in short track speed skating. To perform this study, six skaters: three narrow radius players(N, body mass: $56.0{\pm}7.2$ kg, height: $163.7{\pm}5.1$ cm, age: $21.3{\pm}1.5$ yrs) and three wide radius players(W, body mass: $61.0{\pm}9.5$ kg, height: $169.0{\pm}4.4$ cm, age: $20.0{\pm}1.7$ yrs). Three-dimensional motion analysis was performed on the section from the forth block starting to show the change of radius to the sixth block using eight infrared cameras(sampling frequency of 100 Hz for N and W players). The time of push-off was greater for N than for W(p<.05) while the radius of center of mass was greater for W than for N(p<.05). The flexion and extension of knee and hip joint were greater for N than for W(p<.05). The external rotation of left knee joint was greater for N than for W(p<.05). Based on the findings, a small radius by increasing the range of the flexion and extension of knee and hip joint with greater external rotation of left knee joint would be related to more efficient run at curve. It is expected that these results will be useful in developing a training program for enhancing performance of short track speed skating athletes.

• 한국운동역학회지
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• 제29권1호
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• pp.33-41
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• 2019

Objective: This study aimed to investigate the effect of diminished plantar sensation in Y-balance test between chronic ankle instability (CAI) patients versus Healthy individuals. Method: A total of 90 subjects and CAI group (N=45) (age: $24.49{\pm}2.52yrs$, height: $173.53{\pm}8.20cm$, weight: $69.62{\pm}12.92kg$) and healthy group (N=45) (age: $24.85{\pm}2.70yrs$, height: $170.27{\pm}7.70cm$, weight: $66.04{\pm}11.60kg$) participated in this study. Participants were tested on the anterior (ANT), posterolateral (PL), and posteromedial (PM) reach directions of the Y-Balance Test before and after a 10-minute of plantar cutaneous sensation application using ice ($2^{\circ}C$). Normalized reach distances were measured 3 times each direction. Results: We observed a decrease in reach-distance scores for the reach directions after diminished plantar cutaneous sensation in all reach directions (p<.01). Also, we observed a decrease in reach-distance scores for the PL, and PM reach directions between groups (p<.05). Conclusion: Our results indicated that dynamic postural control was adversely affected immediately after diminished plantar cutaneous sensation between CAI group and healthy group. Future research may suggest that determine the studies involving more realistic dynamic movement, such as walking or running, landing.

• 한국재료학회지
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• 제34권6호
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• pp.267-274
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• 2024

In this study, four different samples of Se₆₀Ge_40-xBi_x chalcogenides glasses were synthesized by heating the melt for 18 h in vacuum Pyrex ampoules (under a 10^-4 Torre vacuum), each with a different concentration (x = 0, 10, 15, and 20) of high purity starting materials. The results of direct current (DC) electrical conductivity measurements against a 1,000/T plot for all chalcogenide samples revealed two linear areas at medium and high temperatures, each with a different slope and with different activation energies (E₁ and E₂). In other words, these samples contain two electrical conduction mechanisms: a localized conduction at middle temperatures and extended conduction at high temperatures. The results showed the local and extended state parameters changed due to the effective partial substitution of germanium by bismuth. The density of extended states N(E_ext) and localized states N(E_loc) as a function of bismuth concentration was used to gauge this effect. While the density of the localized states decreased from 1.6 × 10¹⁴ to 4.2 × 10¹² (ev^-1 cm^-3) as the bismuth concentration increased from 0 to 15, the density of the extended states generally increased from 3.552 × 10²¹ to 5.86 × 10²¹ (ev^-1 cm^-3), indicating a reduction in the mullet's randomness. This makes these alloys more widely useful in electronic applications due to the decrease in the cost of manufacturing.

• 한국운동역학회지
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• 제21권4호
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• pp.479-486
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• 2011

This study determined the effects of the height and the quality of the material of popular heel-up insole on mean plantar foot pressure during walking. Seven healthy college students who are studying at S university in Busan were as participants in this study. After sufficiently explaining about the research to the subjects before the experiment, mean plantar foot pressures were examined using F-Scan Pressure Measure System 5.23 for the gait with shoes inserted insole and the data were compared among the height and the quality of material of insoles. In the result, there was a difference significantly in the mean plantar foot pressure followed the height of insoles both left and right. Especially, mean plantar foot pressure in left indicated significantly lower in 3 cm and 5 cm insoles than in 0 cm and 1 cm insoles. Also mean plantar foot pressure in right showed significantly lower in 3 cm and 5 cm insoles than in 0 cm, and indicated significantly lower in 5 cm insoles than in 1 cm and 3 cm insoles. The mean plantar foot pressure followed the quality of the material of insoles were different significantly. In left, the mean plantar foot pressure of urethane poly-acetyl insole was lower significantly than urethane poly-acetyl inserted air insole, power-gel insole and jelly insole. And the mean plantar foot pressure of urethane poly-acetyl insole was lower significantly than power-gel insole and jelly insole in right. We showed that 3 cm and 5 cm insoles in the height of insoles and Urethane poly-acetyl insole in the quality of material were suitable to reduce a fatigue which is felt in plantar foot during the walking.

• 암석학회지
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• 제24권4호
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• pp.337-345
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• 2015

백두산 산정부의 강하부석층의 부석에 대한 물리적 특성을 분석하였다. 백두산 천지 칼데라 외륜산 주변의 강하부석층은 주로 흰색 부석으로 구성되지만 이들 중에는 흑색, 회색의 부석이 함께 산출된다. 흰색 부석은 주로 유문암질($SiO_2$ 71.1% 내외)이며, 흑색 부석은 조면암질($SiO_2$ 64.8% 내외), 회색 부석은 이들의 중간 성분에 해당하는 조면암질로 $SiO_2$ 68.0% 내외이다. 이들 부석을 형성한 마그마의 평균밀도는 무수 마그마의 경우 $2.45g/cm^3$, 함수 마그마의 경우 $2.33g/cm^3$로 계산되었다. 백두산 천지 칼데라 남단 와호봉(2,566 m)과 관면봉(2,526 m) 부근에서 채취한 암색을 달리하는 3 종류의 부석에 대하여 물리적 성질 중 밀도와 발포도를 측정하였다. 황색 부석은 평균 밀도가 $0.74g/cm^3$, 흑색 부석은 $0.75g/cm^3$, 회색~백색 부석은 $0.73g/cm^3$로 측정되었으며, 부석의 색깔에 무관하게 부석의 밀도는 평균 $0.75g/cm^3$로 거의 일정하였다. 부석의 발포도는 67.8~69.4%로 계산되어 높은 정도의 발포도를 가진 부석으로 분류될 수 있다.