• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.249-255
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• 2016

Objective: This purpose of this study was to analyze the relationship between dimensionless leg stiffness and kinetic variables during gait performance, and its modulation with body weight. Method: The study sample consisted of 10 young women divided into 2 groups (Control, n=5 and Obese, n=5). Four camcorders (HDR-HC7/HDV 1080i, Sony Corp, Japan) and one force plate (AMTI., USA) were used to analyze the vertical ground reaction force (GRF) variables, center of pressure (COP), low limb joint angle, position of pelvis center and leg lengths during the stance phase of the gait cycle. Results: Our results revealed that the center of mass (COM) displacement velocity along the y-axis was significantly higher in the obese group than that in control subjects. Displacement in the position of the center of the pelvis center (Z-axis) was also significantly higher in the obese group than that in control subjects. In addition, the peak vertical force (PVF) and dimensionless leg stiffness were also significantly higher in the obese group. However, when normalized to the body weight, the PVF did not show a significant between-group difference. When normalized to the leg length, the PVF and stiffness were both lower in the obese group than in control subjects. Conclusion: In the context of performance, we concluded that increased dimensionless leg stiffness during the gait cycle is associated with increased velocity of COM, PVF, and the change in leg lengths (%).

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.261-266
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• 2010

Human body is hard to be in perfect balance during walking. Most of time the trunk is supported by one leg and the center of mass(COM) falls to the contralateral side. Thus, dynamic variables such as the velocity of the COM should be considered when gait stability is evaluated. The purpose of this study was to investigate whether the extrapolated center of mass(XCom) which utilized the COM position and its velocity, is appropriate to evaluate gait stability. Ten healthy adults participated in this study and performed 3 different types of gaits(normal(NG), hands on waists(HWG), and hands on shoulders(HSG)) onto 4 different types of obstacle(obstacle height: 0%, 30%, 40% and 50% of leg length). Medio-lateral Com-CoP and XCom-CoP inclination angle were calculated during support phase. For all condition, greater M-L XCoM-CoP inclination angles were found(p<.05) compared with those of matched obstacle height CoM-CoP. Especially, M-L XCoM-CoP inclination angle at 50% height revealed the best condition for monitoring dynamic stability. Significantly increased in M-L XCoM-CoP inclination angle was found(p<.05) as obstacle height increased on NG and HWG.

• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.445-453
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• 2014

The purpose of this study was to analyze the gait characteristics and interaction between lower extremity joints according to shoe's heel heights in young women. Participants were selected as subject consisted of young and healthy women (age: $23.71{\pm}1.49yrs$, height: $165.92{\pm}2.00cm$, body weight: $54.37{\pm}3.46kg$) and walked with 3 types of shoe's high-heel (0, 5, 9 cm). The variables analyzed consisted of the displacement of Y axis in center of mass ([COM]; (position, velocity), front rear(FR) and left right(LR) angle of trunk, lower extremity joint angle (hip, knee, ankle) and asymmetric index (AI%). The displacement of Y axis in COM position showed the greater movement according to increase of shoe's heel heights, but velocity of COM showed the decrease according to increase of shoe's heel heights during gait. The hip and knee angle didn't show significant difference statistically according to increase of shoe's heel height, but left hip and knee showed more extended posture than those of right hip and knee angle. Also ankle angle didn't show significant difference statistically, but 9 cm heel showed more plantarflexion than those of 5 cm and 0 cm. The asymmetric index (AI%) showed more asymmetric 9 cm heel than those of 0 cm and 5 cm. The FR and LR angle in trunk tilting didn't show significant difference statistically according to the increase of shoe's heel height during gait in young women.

• Journal of IKEEE
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• v.23 no.4
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• pp.1122-1127
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• 2019

In this study, the bio-impedance of the human body is able to obtain a lot of information by monitoring the pathological and physiological conditions of clinical and biological tissues. The four electrode method system for biometrics measured the potential difference between two electrodes and the other two electrodes were used as electrodes for current flow. The newly developed dry gold electrode measured impedance from 1 Hz to 50 kHz and produced reproducible results. To verify the impedance measurement of the dry electrode, the pitting was performed using an equivalent circuit model of the bioelectrode skin, and the effectiveness was demonstrated through modeling. Fixed electrode types have a constant position of the electrodes attached during the measurement, so that a stable measurement can be obtained, thereby minimizing the error.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.29-39
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• 2007

This study were obtained elapsed time phase-by-phases, displacement, user angle, velocity and angular velocity to analyse kinematically contributing factors at impact of forehand drive motion, on targeting three male players. The results of the study were presented as follows; In the forehand drive swing, the elapsed time by phases was a total of .52 seconds: .30 seconds from backswing to impact and .22 seconds from impact to follow-through, Considering the mean change in locations of COM of each(part$\rightarrow$body segment) at impact, racket head, left shoulder, right wrist and left hip, the left-right directions(X-axis) were showm to be each $.61{\pm}.03$, $1.19{\pm}.08$, $.66{\pm}.03$, $.94{\pm}.06$, and $.45{\pm}.03m$. The displacement differences of COM of each body segment were shown to be -.57, -.05, -.33, and .16m. For the vertical direction(Z-axis), the center of mass was lowest at impact and highest at E3. For the displacement of the right wrist on the left hip, the right wrist moved to .82m to the lower direction without change in the locations of the hip from E1 from E2. When the left hip moved .02m from E2 to E3, the right wrist moved .7m in the upper direction. In respect to the velocity of each body segment, the hip and the shoulder joint accelerated and then the wrist followed. Then the right wrists of all the subjects and their racket heads showed maximum speed, and an effective swing was observed. At the angle of each part, the angle of the right wrist was the smallest at the backswing and the largest at the moment of the impact. Then it increased gradually in the follow-through section. In respect of angular velocity for subject A, the hip moved and the largest change occurred. Immediately before the impact, the subject made a swing using his right wrist, his hip, and the shoulder joint, showing the maximum value, which was judged to be effective.

• Korean Journal of Applied Biomechanics
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• v.23 no.3
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• pp.209-218
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• 2013

This study was to perform the kinetic analysis of forward $1\frac{1}{2}$ somersault on the platform diving. Six men's diving players of the Korea national reserve athletes participated in this study. The variables were analyzed response time, velocity, center of mass (COM), angle, center of pressure (COP) and ground reaction force (GRF) of motion. For measure and analysis of this study, used to synchronized to 4 camcorder and 1 force plate, used to the Kwon3D XP (Ver. 4.0, Visol, Korea) and Kwon GRF (Ver. 2.0, Visol, Korea) for analyzed of variables. The results were as follows; Time factor were observed in maximum knee flexion depending on the extent of use at phase 1 of take-off to execute the somersault. This enabled the subject to secure the highest possible body position in space at the moment of jumping to execute the somersault and prepare for the entry into the water with more ease. Regarding the displacement of COM, all subjects showed rightward movement in the lateral displacement during technical execution. Changes in forward and downward movements were observed in the horizontal and vertical displacements, respectively. In terms of angular shift, the shoulder joint angle tended to decrease on average, and the elbow joints showed gradually increasing angles. This finding can be explained by the shift of the coordinate points of body segments around the rotational axis in order to execute the half-bending movement that can be implemented by pulling the lower limb segments toward the trunk using the upper limb segments. The hip joint angles gradually decreased; this accelerated the rotational movement by narrowing the distance to the trunk. Movement-specific shifts in the COP occurred in the front of and vertical directions. Regarding the changes in GRF, which is influenced by the strong compressive load exerted by the supporting feet, efficient aerial movements were executed through a vertical jump, with no energy lost to the lateral GRF.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.307-311
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• 2004

In cosmetics industry, we notice that the research should be focused on developing well-being related products such as SPA, esthetique, mass-customization, organics, naturals besides inner beauty and body shaping products. These well-being related products should satisfy customers' expectation about not only concern about health but also safety, reliability, and ethos about products. In that context, the systematic way for well-being related research in cosmetics should be carried out concerning anti-aging with fat-decom-position, vitamin, polyphenol, and organics. At the same time, there are several important factors in this research like augmenting efficacy, controlling skin-absorbency, skin-adaptability, forming, stabilization of activated com-ponents, improving sustainability, and developing new materials based on dermatologic and emotional science. It should be also emphasized that recent technologies such as bio-technology, nano-technology, and natural-material-technology are the cornerstones of developing well-being products.

• Journal of Nutrition and Health
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• v.37 no.10
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• pp.888-898
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• 2004

This study was designed to investigate the effects of 8-week resistance exercise by using dumbell on the body com-position, serum hormone profiles and feeding patterns in young and healthy female students with over 30% of body fat, aged 22 years in Masan, Korea. The subjects were all six, performed successfully the entire exercise-program. Anthropometry, serum lipid and neurohormone profiles of subjects were analyzed at 0, 4 and 8 weeks after exercise. And also their food and nutrient intakes were self-reported by 3-day record and food frequency questionnaire. Triceps skinfold-thickness of the subject students significantly reduced after the exercise to 46% less than before (p < 0.002) . The serum concentrations of leptin, insulin and catecholamine appeared to decrease steadily, but not significantly. Total protein in serum increased significantly (p<0.05), and Na (p<0.005), K (p<0.001) and Fe (p<0.058) concentrations increased remarkably within the normal range. The 8-week resistance exercise tended to induce fiber consumption (p<0.089) of subject students and changed the P/M/S ratio changed into the desirable way from 0.8 : 1 : 1 to 1 : 1 : 1, and that of n-6/n-3 PUPA from 11 : 1 to 6 : 1. After taking exercise, the intake frequency of cookies (p<0.058) and raymeun (p<0.085) decreased, but finally this feeding pattern returned to the way as before even though at marginal significance. Consequently the resistance exercise may induce the desirable changes of body fat and improve serum lipid profiles and feeding patterns in young obese females.

• Journal of Biomedical Engineering Research
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• v.31 no.3
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• pp.210-216
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• 2010

This study is vestibular electric stimulation applied between the mastoids during quiet standing elicits postural sway. The aim of this study was to characterize the postural sway response to continuous sinusoidal vestibular electric stimulation across various stimulus frequencies and amplitudes. Binaural bipolar sinusoidal vestibular electric stimulation was applied to the skin overlying the mastoid processes of 10 subjects while they stood on a force plate. The position of the center of pressure(COP) and signals at the feet are obtained on an force plate, while the head and whole body center of mass(COM) was measured with motion analysis system. The stimulus conditions included eight frequencies (1/64, 1/32, 1/16, 1/8, 1/4, 1/2, 1, and 2Hz) and six peak amplitudes (0.1, 0.25, 0.5, 0.7, 1 and 2mA). Each subject experienced one trial at each amplitude-frequency pair. The stimuli elicited sway in lateral plane in all subjects, as evidenced by changes in the stimulus frequency. Our results demonstrate that the vestibular system is sensitive to vestibular electric stimulation intensity changes and responds by altering the magnitude of the response accordingly.

• Journal of Conservation Science
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• v.12 no.1 s.15
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• pp.48-70
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• 2003

The characterization of chemical properties and analogy of mallufactured origin for the nine potsherds and eleven celadon sherds collected in Wonnae-dong, Daejeon and Yucheon-ri, Buan, respectively were performed by analyzing their body and glaze compositions and compared with previous data reported. The chemical compositions of the body and glaze were determined by XRF and EPMA, respectively. The trace elements of the body were analyzed by ICP-MS. The Seger analysis and principal components analysis were used to compare the major compositions of body and glaze of the potteries we found with previous data. Wonnae-dong's Whiteware (C-1) showed considerably high $SiO_2$ concentration differently from the other potteries. Wonnae-dong's Whiteware (C-2) showed similar characteristics with potteries of Seoul-Kyeongi and Daejeon-Chungnam provinces in chemical compositions of the body and the glaze. Wonnae-dong's celadons (B-1 and B-2) were classified as the group of Daejeon, Chungman provincial potteries in chemical compositions of the body. It was difficult to distinguish the characteristic differences in the Buncheong data between the provinces with the Seger formula analysis and the PCA. Celadon from Yucheon-ri site showed the same characteristics with previous data reported. The results above demonstrated that it is reasonable to study the characterization of potteries and analogy of manufactured origin with a comparison for the chemical compositions of the body and the glaze of the potteries by using the Seger formula analysis and the PCA.