• 한국의상디자인학회지
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• 제21권3호
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• pp.13-24
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• 2019

Adolescence is a transitional stage of physical development which occurs during the period from puberty to adulthood. Going through this period, various parts of an adolescent's body grow at different rates, leading to different body shapes and proportions when compared to adults. Therefore, this study aimed to investigate the body sizes and shapes of junior high school boys from ages 13-15 based on body measurement items that are used as the basis for school uniform designs including jackets, shirts, and pants. For this, the study sought the basic data needed to develop body shapes and school uniform patterns for junior high school boys using the data from the 6th Size Korea Survey (2010). Specifically, it provided basic data for the development of school uniform patterns that fit well through the classification of bodies into particular types. After extracting body shape componen a cluster analysis using ANOVA was performed. According to the factor analysis conducted to determine body shape components, 5 factors were obtained as follows: Factor 1: bulk and horizontal size, Factor 2: body height and length, Factor 3: shoulder shape and length, Factor 4: characteristics of horizontal size, Factor 5: shape of the upper body with a variance of 82.62%. To classify junior high school boys' body shape was determined using various characteristics, and a cluster analysis was performed with the variables obtained by the factor analysis. For this, body shapes were classified into 3 different types: Type 1 accounted for 33.4%, with a total of 463 subjects. This type was a tall, long body individual with the smallest bulk and size. Type 2 accounted for 22.7%, with a total of 315 subjects. This type was large in bulk and horizontal size, but the lowest in height and length. Type 3 accounted for 43.9%, with a total of 610 subjects. This type was close to average in terms of horizontal size, length, and height. To develop well-fitting school uniforms for junior high school students, there should be further studies on changes in body shape and their associated causes. The study results will be available as basic data for comparing branded school uniform patterns for junior high school boys and developing school uniform patterns based on body shape, using 3D virtual clothing simulations.

• 한국수학교육학회지시리즈A:수학교육
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• 제55권3호
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• pp.357-382
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• 2016

The purpose of this study was to report the effects of self-directed and self-regulated learning programs on elementary, middle, and high school students through meta-analysis of previous studies. For this research, 22 of previous studies were selected which were all conducted in the country, and calculated the effect size of 'standardized change of the mean difference' for many factors included in each research. The findings were as follows: first, the overall effect sizes of self-directed and self-regulated learning programs on elementary, middle, and high school students were .665 and .702 in the affective and cognitive domain, respectively, meaning that the self-directed and self-regulated learning programs had average or greater effects on elementary, middle, and high school students and exerted somewhat greater effects in the cognitive domain. Second, when the areas of moderating effects were divided into self-directed and self-regulated learning, the former and latter had more influences on the cognitive and affective domains, respectively. Third, the elementary school level recorded a larger effect size both in the affective and cognitive domains than the secondary school level. Fourth, the findings show that the characteristics of affective domain, "reflective thinking" and "self-confidence," recorded a very large effect size both at the elementary and secondary school levels. Finally, the programs were more effective when the application period was one to four weeks in the affective domain and more than four weeks in the cognitive domain. And, Significance and implications of this research were discussed.

• 한국응용과학기술학회지
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• 제36권4호
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• pp.1041-1049
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• 2019

이 연구는 학교 체육 현장에서 적용한 심상훈련의 효과가 어느 수준인지 살펴보고, 그 효과에 영향을 미치는 변인을 파악하는데 목적이 있다. 이와 같은 연구 목적을 달성하기 위해 1995년부터 2018년까지 학교 체육 현장에서 심상훈련의 효과성을 검증한 선행연구 10편을 메타분석 대상으로 선정하였다. 이 연구의 주요 결과를 제시하면 다음과 같다. 첫째, 학교 체육에서의 심상훈련 전체효과크기는 큰 효과 크기(Cohen, 1988)를 나타내었다. 둘째, 종속변인에 대한 효과크기는 운동기능에서 상대적으로 크게 나타났다. 셋째, 조절변인에 대한 효과크기 분석 결과, 운동 학습의 유형, 연령, 성별, 훈련 기간, 훈련 빈도, 훈련 시간은 심상훈련의 효과를 조절하는 주요 변인으로 나타났다. 이러한 연구결과를 토대로 학교 체육 현장에서 심상훈련을 효율적으로 적용하기 위한 시사점과 후속 연구의 방향성을 제안하였다.

• 한국정밀공학회지
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• 제26권2호
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• pp.118-125
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• 2009

This paper reports the size classification of nanoparticles as well as electrical tuning techniques for the cut-off diameter and collection efficiency. Classifying particles < 100 nm in diameter is quite a technical challenge using a virtual impactor with the cut-off diameter being determined geometrically. However, the proposed virtual impactor can classify particles <100 nm and tune the cut-off diameter by electrically accelerating the particles. The cut-off diameter of the proposed device was tuned from 15 to 50nm.

• 한국생활과학회지
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• 제13권6호
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• pp.1023-1029
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• 2004

In the current study, we measured the hands and other representative body items of 223 elementary school girls using Martin Anthropometer and a digital camera so that we would be able to provide information on both size and shape of hands for design of hand-related products. As time goes on, hands get bigger, yet they get thinner at the same time. The data implies that the frame of hands grows, but the skin fat lessens, which could be a determinant factor in the size system of hand-related products. According to the results of a factor analysis on 26 hand items, 5 factors including hand laterality and linearity, fingertip shape, finger breadth, and hand depth, have been extracted. Pearson's correlation showed that most of hand-related factors were strongly associated with other body items. Finger breadth and hand depth, however, were found less related to other body items. The ANOVA test used in testing the difference of hand factors showed, in most items, a difference by ages, but there was no significant differences in fingertip breadth, the third factor, Interestingly, in hand depth, the fifth factor, lower grade girls' hands were thicker than higher grade girls'. This research suggests that the size system of uniformly increasing the size of all hand parts by age groups should be reconsidered and leaves much for improvement.

• 한국의류산업학회지
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• 제12권2호
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• pp.194-202
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• 2010

There may be some problems in size fitness for ready-made-clothes purchasers with Obese body shape. The purpose of this study was to improve the wearing comfort of Junior-High School Girls' slacks by setting grading points and developing grading rules proper to the obesity. The subjects in this study was over 23 kg/m2 of the BMI. The subjects were 124 Junior-High School Girls of 12 to 14 year-old. The results of this study are as follows: (1) The size intervals of waist girth and hip girth were 3 cm and 4 cm respectively. The sizing system, which had frequencies more than 5%, was classified 8 cases. The majority segment is 76-97 size accounting for the 11.29% of subjects. (2) The measurements on 8 size from two groups after drawing slacks pattern on them revealed that the changed values of slacks front and back on the grading point marked are differ, indicating that it is needed to apply body shape. (3) The evaluation on the appearance for wearing slacks showed relatively high score, indicating that the grading between sizes within each group was effective. The studies on the body size distribution on each obesity pattern and on the setting size system reflecting characteristics of each body shape should be performed continuously.

• 한국세라믹학회지
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• 제48권6호
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• pp.617-620
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• 2011

Thermal shock behavior of porous ceramic nozzles with various pore sizes for continuous casting process of steel was investigated in terms of physical properties and microstucture. Porous nozzle samples with a composition of $Al_2O_3$-$SiO_2$-$ZrO_2$ were fabricatedby adding various sizes of graphite as the pore forming agent. As the graphite size increased from 45~75 to 150~180 ${\mu}m$, both the resulting pore size and the flexural strength also increased. A thermal shock test was carried out at temperatures (${\Delta}$T) of 600, 700, 800, and 900$^{\circ}C$. Microstructure analysis revealed a small number of cracks on the sample with the largest mean pore size of 22.32 ${\mu}m$. In addition, increasing the pore size led to a smaller decrease in both pressure drop and elastic modulus. In conclusion, controlling the pore size can enhance thermal shock behavior.

• Journal of Power Electronics
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• 제15권2호
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• pp.487-496
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• 2015

In order to ensure that photovoltaic (PV) systems work at the maximum power point (MPP) and maximize the economic benefits, maximum power point tracking (MPPT) techniques are normally applied to these systems. One of the most widely applied MPPT methods is the incremental conductance (INC) method. However, the choice of the step size still remains controversial. This paper presents an improved variable step size INC MPPT algorithm that uses four different step sizes. This method has the advantages of INC but with the ability to validly adjust the step size to adapt to changes of the PV's power curve. The presented algorithm also simultaneously achieves increased rapidity and accuracy when compared with the conventional fixed step size INC MPPT algorithm. In addition, the theoretical derivation and specific applications of the proposed algorithm are presented here. This method is validated by simulation and experimental results.

• Structural Engineering and Mechanics
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• 제70권5호
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• pp.623-637
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• 2019

This paper analyzes the non-stationary vibration and super-harmonic resonances in nonlinear dynamic motion of viscoelastic nano-resonators. For this purpose, a new coupled size-dependent model is developed for a plate-shape nano-resonator made of nonlinear viscoelastic material based on modified coupled stress theory. The virtual work induced by viscous forces obtained in the framework of the Leaderman integral for the size-independent and size-dependent stress tensors. With incorporating the size-dependent potential energy, kinetic energy, and an external excitation force work based on Hamilton's principle, the viscous work equation is balanced. The resulting size-dependent viscoelastically coupled equations are solved using the expansion theory, Galerkin method and the fourth-order Runge-Kutta technique. The Hilbert-Huang transform is performed to examine the effects of the viscoelastic parameter and initial excitation values on the nanosystem free vibration. Furthermore, the secondary resonance due to the super-harmonic motions are examined in the form of frequency response, force response, Poincare map, phase portrait and fast Fourier transforms. The results show that the vibration of viscoelastic nanosystem is non-stationary at higher excitation values unlike the elastic ones. In addition, ignoring the small-size effects shifts the secondary resonance, significantly.

• Geomechanics and Engineering
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• 제32권3호
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• pp.321-333
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• 2023

Rock masses often contain natural fractures of varying sizes, and the size of the natural fractures may affect the propagation of hydraulic fractures. We conduct a series of triaxial hydraulic fracturing tests to investigate the effect of the pre-existing fracture size a on hydraulic fracture propagation. Experimental results show that the pre-existing fracture size impacts hydraulic fracture propagation. As the pre-existing fracture size increases, the hydraulic fracture propagates towards the pre-existing fracture tips, evidenced by the decreased distance between the final hydraulic fracture and the pre-existing fracture tips. Furthermore, the attracting effect of pre-existing fracture tips increases when the distance between the wellbore and the pre-existing fracture is short (L/D=2 or 4 in this study). With increased distance between the wellbore and the pre-existing fracture (L/D=6 in this study), the hydraulic fracture propagates to the middle of the pre-existing fracture rather than the tips, as the attracting effect of the pre-existing fracture diminishes.