• Journal of the East Asian Society of Dietary Life
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• v.23 no.5
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• pp.519-532
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• 2013

The purpose of this study was to make a comparative analysis of dietary habits, snacks, eating out and fast-food intake between students with a relatively early sexual maturity and others with a relatively late sexual maturity in a bid to grasp the impact of dietary behaviors on sexual maturity. The subjects in this study were 565 boys and girls who resided in Seoul and Gyeonggi province. They included fifth- and sixth-grade school children and seventh-grade middle school students. To classify the selected students according to the level of sexual maturity, the students of the same month age were divided into two groups in consideration of the stage of their sexual maturity and that of the other age groups. The early mature group was significantly taller and weighed more than the late mature group irrespective of gender. According to Tanner stages, the boys of the early mature group reached a 3.03 stage of sexual maturity when the sexual organs were taken into account, and those of the late mature group reached a 1.50 stage of sexual maturity. The girls of the early mature group reached a 3.43 stage of sexual maturity on the basis of breast, and those of the late mature group reached a 2.73 stage of sexual maturity. Concerning eating out, the early mature group ate out more frequently than the late mature group. In regard to snacks, the early mature group had a snack more often. The findings of the study indicated that there were differences in physical development and some dietary behaviors according to sexual maturity. The early mature group had a snack and ate out relatively more often than the late mature group, which showed that some dietary behaviors had an impact on the sexual maturity of the teens who arrived at the age of puberty.

• Journal of Korean Medicine for Obesity Research
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• v.12 no.1
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• pp.9-19
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• 2012

Objectives This study was designed to find out the relationships between obesity and growth, skeletal maturity among children by analyzing body composition and bone age. Methods Subjects were composed of 577 children from six years to seventeen years of age, without any other diseases related to growth, were measured their body composition and bone age. Results As obesity index was increased, the RH-MPH(%) and skeletal maturity significantly was also increased. The RH-MPH(%) of the obesity group was significantly increased than that of normal weight group; the skeletal maturity was more increased in th obesity group. It means the recent height of obese children was more taller than that of inherited from the parents, while skeletal maturity of obese children was more rapidly progressing. The RH-MPH(%) was increased in children who revealed stage of second sexual character; skeletal maturity was decreased in children who developed secondary sexual character. Conclusions Obesity children might be taller than what it supposed to be. However, obesity could cause the increase of skeletal maturity. It means the growth plate of obese children has been closed early.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.1
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• pp.25-27
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• 1992

160 day-old chicks of Rhode Island Red, White Leghorn and their crossbred with Naked neck chicken were reared upto 23 weeks of age at Bangladesh Agricultural University Poultry Farm in order to study the economic traits of birds. RIR had highest body weight gain (1494.39 g), followed by White Leghorn (1392.57 g), $RIR{\times}NN$ (1268.9 g) and White Leghorn ${\times}$ NN (1266.73 g). RIR showed significant difference (p < 0.05) to other groups of birds in body weight gain but difference were insignificant in between other birds. RIR showed better feed conversion ratio (4.72:1) but difference were insignificant (p > 0.05), however, $RIR{\times}NN$ exceled White Leghorn ${\times}$ NN in feed efficiency. $RIR{\times}NN$ had highest livability (90%) while White Leghorn had lowest (85%). Earlier sexual maturity was observed in White Leghorn (163 days) than RIR (168 days) but cross breds were similar in age at sexual maturity RIR were heaviest (1538.89 g) at age at sexual maturity, on the other hand $RIR{\times}NN$ were heavier (1315.39 g) than $WL{\times}NN$ (1306.77 g) at sexual maturity.

• The korean journal of orthodontics
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• v.19 no.3
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• pp.99-111
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• 1989

To study the sexual maturity at puberty and interrelation between pubertal growth peak and sexual maturity, 68 malocclusions (female 44, male 24) were longitudinally studied for 4 years and cross-sectional samples of 210 malocclusions were studied together. The pubertal growth peak was determined by stature increment and sexual maturity was studied using developmental stages of pubic hair and breast, menarche in female and those of pubic hair in male. The following results were obtained. 1. Mean age at menarche was 12.8 years and it was 11.8 months later than PHV. 2. At pubertal growth peak, developmental stage 2 (54.2%) and 3 (29.2%) of pubic hair were most in male, and stage 1 (72.7%) and 2 (20.5%) were most in female. 3. At pubertal growth peak, the developmental stage 2 (50%) of breast was most and the stage 3 (43.2%) was next. 4. In interrelation between skeletal growth and sexual maturity, PHV had most high correlation with menarche and stage 3 of breast, and menarche had most high correlation with stage 3 of breast. 5. Appearance of remarkable sexual maturity suggested that the PHV was passed already.

• Women's Health Nursing
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• v.24 no.2
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• pp.219-228
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• 2018

Purpose: The purpose of this study is to evaluate sexual maturation, attitudes toward sexual maturity, and body esteem in the sexual development of Korean elementary-school boys and girls. Methods: A descriptive cross-sectional study was conducted with 399 fifth and sixth graders (192 boys and 207 girls). The data were analysed with a $x^2$ test, t-test, and Pearson correlation coefficients. Results: Among the 207 girls, 70.5% had pubic hair growth, 68.1% had breast development, and 56.0% had a menstrual period. In boys, 59.4% of the 192 subjects experienced the development of external genitalia and 52.6% had pubic hair growth. Sexual maturation was related to grade (boys, t=7.07, p=.008; girls, t=12.76, p<.001), age (t=-2.20, p=.030; t=-4.11, p<.001), height (t=-5.16, p<.001; t=-7.52, p<.001), and weight (t=-2.89, p=.004; t=-5.19, p<.001) in both boys and girls. Girls were more likely to have sexual maturity than boys ($x^2=22.29$, p<.001). Boys showed more positive attitudes toward sexual maturity (t=2.10, p=.036) and higher body esteem (t=2.12, p=.035) than girls. Conclusion: This study shows that sexual maturation, attitude toward sexual maturity, and body esteem in sexual development differ between boys and girls. The findings indicate that it is necessary to develop a tailored sex-education program according to the sex of elementary-school children.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.4
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• pp.455-459
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• 1996

The genetic parameters for various economic traits were estimated in a White Leghorn population selected for part period egg production over 16 generations. In early part of selection, egg number had moderate to high heritability (0.26 to 0.51) while age at sexual maturity, egg weight and body weight at 20 and 40 weeks of age had high heritability (0.54 to 0.83). The sire component heritability for all the traits except 20 week body weight declined in later periods of selection. Sex linked gene effects for egg number and age at sexual maturity were more important in early periods of selection in comparison to the later periods, while maternal effects remained important for 20 week body weight in all the periods. Egg number was negatively correlated with egg weight ($r_{G(S)}=-0.36$), age at sexual maturity ($r_{G(S)}=-0.84$) and 40 week body weight ($r_{G(S)}=-0.84$), while it was positively correlated with 20 week body weight ($r_{G(S)}=-0.34$) in base generation. The genetic association between egg number and 40 week body weight changed not only in magnitude but also in direction in later periods. The genetic correlation of egg number with egg weight as well as with age at sexual maturity also decreased in magnitude in later periods of selection.

• The Journal of Pediatrics of Korean Medicine
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• v.22 no.2
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• pp.19-35
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• 2008

Objectives : As obese children have been increased, the interest in the impact of obesity on growth also have been increased. This study is to examine relations between obesity and skeletal maturity by analyzing body compositions and bone age. Methods : Subjects were composed of 233 children from 6 years to 17 years of age, without any other diseases related to growth, who visited the department of pediatrics, OO oriental medicine hospital and measured their body composition (body mass index, body fat ratio, fitness score) and bone age. Results : 1. As body mass index was increased, the skeletal maturity significantly was also increased. 2. As the mean of bone maturity was increased, the BMI was increased from the underweight type to the normal type to the overweight type; the bone maturity was increased as the fat ratio was increased from the normal type to the obese type to the excessively obese type; and the bone maturity was higher in the weak, obese type than the normal type when classified according to the Fitness Score. 3. The bone maturity of the overweight group in the BMI classification and excessively obese group in the fat ratio classification significantly were increased. 4. Skeletal maturity significantly was increased in children who developed secondary sexual character. 5. The significance of obesity causing increase of the skeletal maturity was higher in boys than in girls. 6. Only in the case of children without development of secondary sexual character, obesity caused an significant increases in the skeletal maturity. Conclusions : Obesity could cause the increase of skeletal maturity, and the obesity could affect more to the boys than girls and more to the children than teenagers.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.1
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• pp.19-24
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• 2007

Covariance components and genetic parameters of weekly live body weight from hatching to six weeks of age and age of sexual maturation were estimated in a laying type Japanese quail line. The univariate and bivariate animal model analysis included hatching group and sex as fixed effects. Each trait was analysed with animal as random effect to fit the additive direct effect. Additional random effects incorporated in the models were changed according to the trait examined. The best model for a trait was chosen based on a likelihood ratio test, comparing the models with and without maternal additive genetic and maternal permanent environmental effects. Heritability estimates of live-weight at hatch and one to six weeks of age with their standard errors were 0.22${\pm}$0.088, 0.39${\pm}$0.099, 0.31${\pm}$0.086, 0.38${\pm}$0.056, 0.46${\pm}$0.055, 0.50${\pm}$0.059, and 0.56${\pm}$0.062, respectively. Direct heritability value of age of sexual maturation was moderate (0.24${\pm}$0.055). The variances due to permanent environmental effect of dam after one week of age and maternal genetic effect after two weeks of age were not important sources of variation. The correlations between direct and maternal genetic effects were negative and ranged from high to moderate values (-0.21 to -0.83). Among the weekly live weights, genetic correlations were generally high between not only successive but also early and late weightings. It suggests that selection for final weight may be based on early weight records. Genetic correlations between age of sexual maturation and live weights were low, favourable but had high standard errors. These results indicate that selection for high weight will potentially result in lower age of sexual maturation only with accurate determination of breeding values.

• The Journal of Pediatrics of Korean Medicine
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• v.26 no.3
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• pp.1-11
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• 2012

Objectives The purpose of this study is to examine the relationship between skeletal maturity and heart rate variability (HRV) based on the bone age and HRV parameters. Methods 103 children from 6 years to 17 years of age, who do not have any disease-related symptom, and visited ${\bigcirc}{\bigcirc}$ oriental medicine hospital, are measured based on their bone age and short-term spectral analysis of HRV. Results 1. Skeletal maturity was significantly correlated with HRV indices: mean HRT and SDNN. As the skeletal maturity increases, the mean HRT was decreased and the SDNN was increased. 2. When classifying according to the skeletal maturity score, the mean HRT was higher in the 'below -0.4' group compare to '-0.3~0.7' group and '0.8~1.9' group. SDNN was higher in the '0.8~1.9' group compare to '-0.3~0.7' group, 'below -0.4' group 3. When classifying according to the sex, age and secondary sexual characteristics, as the skeletal maturity was increased, the mean HRT was significantly decreased and the SDNN was significantly increased only in the boys who did not develop secondary sexual characteristics. Conclusions Skeletal maturity could be statistically significant with HRV indices, especially to the boys and the children than the girls and the teenagers.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.449-458
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• 2013

This study investigated purplish Washington clam, Saxidomus purpuratus on its gonadal development, reproductive cycle and shell length (age) at 50% female group maturity from January to December 2011 in Jinhae Bay, Korea. This species is dioecious. The gonad index (GI) began to increase in January, reached the maximum value in May and to decrease in June, reached the minimum value in September then to increase slowly in October again. The reproductive cycle of the clams can be divided into five successive stages: the early active stage (Ea, from February to March), the late active stage (La, from January to March and October to December), the ripe stage (R, from January to May), the spawning stage (S, from June to December) and the degenerative and inactive stage (Ia, from January to February and November to December). The spawning periods were from June to December and the main spawning periods were from July to October. The shell length at 50% female group maturity (SL50) was estimated to be 63.6 mm, which can be converted as sexual maturity age of 2.2 year.