• The Journal of Korean Physical Therapy
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• v.10 no.1
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• pp.81-98
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• 1998

Isokinetic evaluation of trunk flexors and trunk extensors was performed at $60^{\circ}/sec\;and\;120^{\circ}/sec$ of angular velocity by using cybex 6000TEF Unit on 31 healthy male white workers and 15 post-operative HILD patients with no significant difference in mean age and mean body weight between two groups, and compared each other. The purpose of this study is to obtain the isokinetic normative strength values and endurance latins for Dunk extensors and trunk flexors, and is to provide a guideline for rehabilitation program of post-operative HILD patients. The collected data were analyzed by ANOVA, Duncan's Nyktuoke Range Test, and Pearson correlation coefficiency in PC-SAS program, The results obtained were as follow ; 1. Post-operative subjects has lower isokinetic values than normal subjects in peak torque, peak torque $\%$ by body weight, total work, total work $\%$ by body weight, average power, average power $\%$ by body weight, TAAE of trunk flexors and trunk extensors, and there are significant differences with statistic value in trunk extensors at $60^{\circ}/sec$ and in trunk flexors and trunk extensors at $120^{\circ}/sec$ between two groups(p<0.05). 2. Pest-ooperative subjects has lower values for angle of peak torque than normal subjects in trunk extensors, and there are significant differences with statistic value at $60^{\circ}/sec$ and $120^{\circ}/sec$ between two groups. 3. Post-operative subjects has higher values for endurance ratios than normal subjects in trunk extensors and flexors, but there are no significant differences with statistic value between two groups. 4. Post-operative subjects has higher values than normal subjects in peak torque ratios, total work ratios, average power ratios of trunk flexors to trunk extensors, and there are significant differences with statistic value between two groups(p<0.01). 5. There is significant positive-correlation with statistic valve between peak torque and height and body weight in normal subjects(p<0.05), but Thjere is significant negative-correlation between peak torque of trunk extensor at $120^{\circ}/sec$ and age (p<0.05). 6. There is significant positive-correlation with statistic value between peak torque of trunk flexors and body weight in post-operative subjects (p<0.05), but There is significant negative-correlation between peak torque of trunk extensor add age (p<0.05). In conclusion, post-operative subjects have greater weakness in trunk musculature than normal subjects, especially there is more significant weakness in trunk extensors than in trunk flexors

• Korean Journal of Applied Biomechanics
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• v.30 no.2
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• pp.145-154
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• 2020

Objective: The purpose of this study was to determine the relationship between impact and shear peak force, and tibia-accelerometer variables during running. Method: Twenty-five male heel strike runners (mean age: 23.5±3.6 yrs, mean height: 176.3±3.3 m/s, mean mass: 71.8±9.7 kg) were recruited in this study. The peak impact and anteroposterior shear forces during treadmill running (Bertec, USA) were collected, and impact shock variables were computed by using a triaxial accelerometer (Noraxon, USA). One-way ANOVA was used to test the influence of the running speed on the parameters. Pearson's partial correlation was used to investigate the relationship between the peak impact and shear force, and accelerometer variables. Results: The running speed affected the peak impact and posterior shear force, time, slope, and peak vertical and resultant tibial acceleration, slope at heel contact. Significant correlations were noticed between the peak impact force and peak vertical and resultant tibia acceleration, and between peak impact average slope and peak vertical and resultant tibia acceleration average slope, and between posterior peak (FyP) and peak vertical tibia acceleration, and between posterior peak instantaneous slop and peak vertical tibial acceleration during running at 3 m/s. However, it was observed that correlations between peak impact average slope and peak vertical tibia acceleration average slope, between posterior peak time and peak vertical and resultant tibia acceleration time, between posterior peak instantaneous slope and peak vertical tibial acceleration instantaneous slope during running at 4 m/s. Conclusion: Careful analysis is required when investigating the linear relationship between the impact and shear force, and tibia accelerometer components during relatively fast running speed.

• Annals of Pediatric Endocrinology and Metabolism
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• v.23 no.4
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• pp.215-219
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• 2018

Purpose: We investigated the effect of overweight on luteinizing hormone (LH) levels after a gonadorelin stimulation test in Korean girls with idiopathic central precocious puberty (CPP). Methods: Medical records of 234 girls diagnosed with idiopathic CPP were reviewed retrospectively. CPP was diagnosed when the peak LH levels after gonadorelin stimulation was >5.0 U/L. The enrolled girls had a peak LH level >5.0 U/L after a gonadorelin stimulation test. Selected girls were classified as normoweight (body mass index [BMI] below the 85th percentile with respect to age) and overweight (BMI greater than the 85th percentile with respect to age). Results: The peak LH ($8.95{\pm}2.85U/L$ vs. $11.97{\pm}8.42U/L$, P<0.01) and peak folliclestimulating hormone ($9.60{\pm}2.91U/L$ vs. $11.17{\pm}7.77U/L$, P=0.04) after gonadorelin stimulation were lower in overweight girls with idiopathic CPP than in normoweight girls with idiopathic CPP. Being overweight was negatively associated with peak LH levels after gonadorelin stimulation test (odds ratio, 0.89; 95 % confidence interval, 0.81-0.98, P=0.02). Conclusion: In girls with idiopathic CPP, being overweight led to a lower LH peak after gonadorelin stimulation. Further research is needed to better understand the role of overweight on gonadotropin secretion in precocious puberty.

• Transactions of Materials Processing
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• v.31 no.3
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• pp.160-166
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• 2022

The purpose of this study is to investigate the effects of combined addition of Ca and Y on the precipitation and age-hardening behavior of an extruded AZ91 alloy by conducting the aging treatment at 200 ℃ for hot-extruded AZ91 and AZ91-0.3Ca-0.2Y alloys. In the AZ91 alloy, many Mg₁₇Al₁₂ discontinuous precipitate (DP) bands formed during air cooling immediately after extrusion are present, whereas in the AZ91-0.3Ca-0.2Y alloy, a few DP bands and numerous Al₂Y, Al₈Mn₄Y, and Al₂Ca phase particles are distributed along the extrusion direction. The peak-aging time of the AZ91-0.3Ca-0.2Y alloy is 16 hours, twice that of the AZ91 alloy. Although both alloys have similar hardness before aging treatment, the hardness after peak-aging treatment (i.e., peak hardness) of the AZ91-0.3Ca-0.2Y alloy is higher than that of the AZ91 alloy, as 93.1 and 88.7 Hv, respectively. The microstructures of both peak-aged alloys comprise DPs and continuous precipitates (CPs). However, the peak-aged AZ91-0.3Ca-0.2Y alloy has a smaller amount of DPs and a larger amount of CPs than the peak-aged AZ91 alloy. Additionally, the inter-particle spacings of DPs and CPs in the former are significantly narrower than those in the latter. These results demonstrate that the addition of small amounts of Ca and Y to a commercial AZ91 alloy considerably affects the formation rate, size, and amount of CPs and DPs during aging and resultant age-hardening behavior.

• Physical Therapy Korea
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• v.14 no.3
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• pp.41-47
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• 2007

Dance movements consist of combinations of movements such as jumping, rotation, maintaining balance, leg lifts, and plantar flexion with toe shoes. Dance movements require great muscle strength of lower extremities as well as muscular endurance. The purposes of this study were to investigate correlation between the anthropometric variables and the peak torque in young female dancers and to identify variables that affect isokinetic peak torque. Twenty-six female dancers ($19.7{\pm}1.2$ years of age) performed concentric maximum force efforts on the knee extensors and flexors at $60^{\circ}/sec$ and $120^{\circ}/sec$, the ankle plantar flexors (PF) and dorsiflexors (DF) at $30^{\circ}/sec$ and $120^{\circ}/sec$. Antropometric variables such as age, height, weight, body mass index (BMI), thigh girth, calf girth and duration of dance training were measured. To identify antropometric variables related to muscle strength, Pearson correlations were computed and a stepwise multiple regression analysis was performed. Pearson correlation coefficients of Knee extensor at $60^{\circ}/sec$ and $120^{\circ}/sec$ revealed moderate positive associations with BMI and thigh girth. Pearson correlation coefficients of ankle PF revealed low-to-moderate positive associations with height. Ankle DF also revealed moderate positive associations with BMI and calf girth. The main predictor variables of knee extensor at 60/sec, were stepwise multiple regression, age, height, thigh and girth.

• Journal of radiological science and technology
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• v.20 no.1
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• pp.55-59
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• 1997

The quality of continuous X-ray beam depends upon the half value layer which varies according to the geometric conditions, filtration thickness, and tube voltage. We compared the inverter type X-ray equipment with the conventional single phase 2 peak and the three phase 12 peak for the quality obtained by changes of the added filter thickness and the tube voltage. The quality of single phase 2 peak X-ray generator showed increase for the added filter and the tube volt-age. The half value layer is Increased the thicker the filter and the higher the kVp. The quality of the Inverter type and the three phase 12 peak in comparison with the single phase 2 peak X-ray generator is increased.

• Korean Journal of Applied Biomechanics
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• v.28 no.3
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• pp.159-164
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• 2018

Objective: The aims of this study were to determine the impact peak force and kinematic variables in running speed and investigate the relationship between them. Method: Thirty-nine male heel strike runners ($mean\;age=21.7{\pm}1.6y$, $mean\;mass=72.5{\pm}8.7kg$, $mean\;height=176.6{\pm}6.1cm$) were recruited in this investigation. The impact peak forces during treadmill running were assessed, and the kinematic variables were computed using three-dimensional data collected using eight infrared cameras (Oqus 300, Qualisys, Sweden). One-way analysis of variance ANOVAwas used to investigate the influence of the running speed on the parameters, and Pearson's partial correlation was used to investigate the relationship between the impact peak force and kinematic variables. Results: The running speed affected the impact peak force, stride length, stride frequency, and kinematic variables during the stride phase and the foot angle at heel contact; however, it did not affect the ankle and knee joint angles in the sagittal plane at heel contact. No significant correlation was noted between the impact peak force and kinematic variables in constantrunning speed. Conclusion: Increasing ankle and knee joint angles at heel contact may not be related to the mechanism behind reducing the impact peak force during treadmill running at constant speed.

• Phonetics and Speech Sciences
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• v.2 no.4
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• pp.19-28
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• 2010

The purpose of this study was to increase the current understanding of the acoustic characteristics of voices with advancing age. The relationship between age-related changes in body physiology and certain acoustic characteristics of voice was studied in a sample of 80 men representing four chronological age groupings (20-29, 50-59, 60-69, 70-79) who were all of good physical condition. Each subject was asked to phonate the vowel /a/, /i/, and /u/ for as long as possible at comfortable frequency and intensity level and read the sentence. A promising voice analysis program (Multi-Dimensional Voice $Program^{TM}$) was used to measure the fundamental frequency ($f_0$), jitter, shimmer, $f_0$ variation, peak-amplitude variation, smoothed pitch perturbation quotient, smoothed amplitude perturbation quotient, soft phonation index, $f_0$-tremor intensity index, amplitude tremor intensity index, and noise-to-harmonics ratio from the samples.

• Clinical and Experimental Pediatrics
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• v.56 no.6
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• pp.242-246
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• 2013

Purpose: The cardiopulmonary exercise test (CPET) is an important clinical tool for evaluating exercise capacity and is frequently used to evaluate chronic conditions including congenital heart disease. However, data on the normal CPET values for Korean children and adolescents are lacking. The aim of this study was to provide reference data for CPET variables in children and adolescents. Methods: From August 2006 to April 2009, 76 healthy children and adolescents underwent the CPET performed using the modified Bruce protocol. Here, we performed a medical record review to obtain data regarding patient' demographics, medical history, and clinical status. Results: The peak oxygen uptake ($VO_{2Peak}$) and metabolic equivalent ($MET_{Max}$) were higher in boys than girls. The respiratory minute volume $(V_E)/CO_2$ production ($VCO_2$) slope did not significantly differ between boys and girls. The cardiopulmonary exercise test data did not significantly differ between the boys and girls in younger age group (age, 10 to 14 years). However, in older age group (age, 15 to 19 years), the boys had higher $VO_{2Peak}$ and $MET_{Max}$ values and lower $V_E/VCO_2$ values than the girls. Conclusion: This study provides reference data for CPET variables in case of children and adolescents and will make it easier to use the CPET for clinical decision-making.

• Korea journal of population studies
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• v.24 no.2
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• pp.149-177
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• 2001

This is a study on age-crime curve in Korea. Three data was used in this study as following: First is the crime statistics as aggregated data. Second is the police record(N=3.541 offences) of the male ex-offenders(N=988) who have been released in eleven prisons in 1987 as individual data. Third is the self-reported group-interview data(N=10.198 offences) administered to the male prisoners(N=979) in ten correctional facilities including eight adult prisons, one juvenile prison and one juvenile training center as another individual data. Generally, the right-skewness of age-crime curve has been explained through the difference of crime rate between early starters and late starters. Moffitt explains that this is because of the higher participation rate of the juvenile period of adolescence-limited offenders, but Godttfredson and Hirschi explain that this is because of a similar distribution in the crime rate of both early starters and late starters. the analysis of this study shows that Godttfredson and Hirschi’s explanation on the generality of age-crime-curve distribution is correct, but this can be modified by various factors like a economic crisis. And the peak age of juvenile period is consistent with the Moffitt’s hypothesis that the peak age is contributed to the increase of crime rate of late starters, not with Godttfredson and Hirschi’s one.