• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.4
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• pp.598-617
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• 2013

This study analyzes the body sizes of young boys in order to categorize a sizing system for middle and high school uniforms. The study was based on the $6^{th}$ National Anthropometric Survey (Size Korea 2010) data. The sample size consisted of 2,317 boys between the ages of 13 and 18 years. Most measurement items increased significantly relative to age and there was rapid growth between the ages of 13 and 14 years. The growth for the chest and hip was more than the waist. The drop value 1 (difference between chest circumference and waist circumference) and the drop value 2 (difference between hip circumference and waist circumference) increased remarkably from the age of 13 to the age of 15. Therefore, the waist size decreased and chest and hip became wider relative to the age increase. Middle school students had a smaller chest and hip circumference than high school students in the comparative body measurement results for middle school students (13-15 years) and high school students (16-18 years) of the same height group. The somatotype of high school students showed a long trunk length, broad chest and shoulder.

• Advances in aircraft and spacecraft science
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• v.4 no.6
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• pp.701-709
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• 2017

One of the components that used in the satellite thermal control subsystem is the Mechanically Pumped Fluid Loop (MPFL) system; this system mostly used in geosynchronous orbit (GEO) satellites, and can transfer heat from a hot point to a cold point using the fluid which circulated in a closed loop. Heat radiates to the deep space at the cold plate to cool down the fluid temperature. In this research, the radiative heatexchanger (RHX) for a MPFL system is optimized. The genetic algorithm has been used for minimizing the total mass and pressure drop by considering a constant transferred heat rate at the heat exchanger. The optimization has been done in two cases. In case I, two parameters are considered as a goal function, so optimization is performed using NSGA-II method. Results of optimization are shown in the pareto diagram. In case II, the diameter of pipe is considered constant, so the optimized value for distances of the parallel pipes is obtained by using the genetic algorithm, in which the system has the least total mass. Results show that in the RHX, by increasing the pipe diameter, pressure drop decreases and total mass increases. Also by considering a constant value for pipe diameter, an optimum distance between pipes and pipe length are obtained in which the system has a minimum mass.

• Journal of Fashion Business
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• v.10 no.1
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• pp.58-78
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• 2006

This study materializes body type measurement based on ISO(International Standard Organization)size system, targeting 1381 Chinese women, and suggests clothes size standards. It provides basic information on Chinese women size for Korean clothes companies advanced in China to strengthen the national competitiveness of Korean clothing industry. First, after the body type examination, based on the ISO's drop value, the results of types are in its decreasing order: A, M, H, and D. Second, women upper garment sizes by body types are set in the section of height 152cm, 160cm, and 168cm. Garment sizes are suggested based on the section that has more than 0.8% of appearance rate for the survey target: A, H, and M. Third, the clothes sizes of women pants are set in the section of height 152cm, 160cm, and 168cm just with the same as the upper garment.

• Coupled systems mechanics
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• v.7 no.4
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• pp.407-420
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• 2018

In solid-liquid two phase flow, the knowledge of how descending solid particles affected by the presence of downstream wall is important. This work studies at what interstitial distance the velocity of a vertically descending sphere is affected by a downstream wall as a consequence of wall-modified hydrodynamic forces through a validated dynamic model. This interstitial distance-the hydrodynamic coupling distance ${\delta}_c-is$ found to decay monotonically with the approach Stokes number St which compares the particle inertia to viscous drag characterized by the quasi-steady Stokes' drag. The scaling relation ${\delta}_c-St-1$ decays monotonically as literature below the value of St equal to 10. However, the faster diminishing rate is found above the threshold value from St=10-40. Furthermore, an empirical relation of ${\delta}_c-St$ shows dependence on the drop height which clearly indicates the non-negligible effect of unsteady hydrodynamic force components, namely the added mass force and the history force. Finally, we attempt a fitting relation which embedded the particle acceleration effect in the dependence of fitting constants on the diameter-scaled drop height.

• Journal of the Korea Safety Management & Science
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• v.10 no.1
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• pp.59-65
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• 2008

Recently, obesity that is increasingly becoming a major cause of various diseases and safety accidents in work places is emerging as a serious social problem. It is due to economic growth and improvement of living environments. Many researches are trying to find the root cause of obesity. Thus, the main objective of this study is to analyze obesity index of citizens in Seoul which is a metropolis of Korea and a densely populated district. The data used in this study included 179 men and 152 woman subjects who are living in Seoul. Somatotype using $R\ddot{o}hrer$ Index can be classified by 3 types (thin, standard, obesity). In order to analyze a detailed somatotype of citizens, age groups are divided into $30{\sim}34,\;35{\sim}39,\;40{\sim}49,\;and\;50{\sim}59$ years according to gender, respectively. In order to compare and analyze data, Coefficient of Variance, Cronbach's Alpha, $R\ddot{o}hrer$ Idex and Drop Value were used in this study. The results of this study can be applied to the comfortable and safe work environments for workers.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.541-547
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• 2022

Before making a prototype, we predicted the inlet/outlet differential pressure and flow coefficient, which are the most basic design data for the valve through the design and numerical analysis of the trim, which is the most important in the localization development of the 1500Ib high differential pressure control valve used for boiler feed water. As a result, the design value and the analysis value were found to be about 98% similar. The flow field within the fluid velocity of 23m/s to prevent cavitation was also found. The result of the numerical analysis on thermal stress due to the characteristics of valves exposed to high temperatures showed that it was found to be about 18% less than the allowable stress of the bolt fixing the trim. When all loads such as pressure, self-weight, and vibration are applied, however, it is judged to go beyond the currently calculated thermal stress, exceeding the allowable stress.

• Corrosion Science and Technology
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• v.23 no.1
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• pp.1-10
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• 2024

Oil well casing leak is caused by contact of casing outer surface with formation electrolyte. It is usually associated with an aquifer with a high salt content or absence of a cement ring behind the casing. The only way to reduce external casing corrosion is through cathodic protection. Through cathodic polarization of casing structure, electron content in crystal lattice and electron density will increase, leading to a potential shift towards the cathodic region. At Tatneft enterprises, cathodic protection is carried out according to cluster and individual schemes. The main criterion for cathodic protection is the size of protective current. For a casing, the protective current is considered sufficient if measurements with a two-contact probe show that the electric current directed to the casing has eliminated all anode sites. To determine the value of required protective current, all methods are considered in this work. In addition, an analysis of all methods used to determine the minimum protective current of the casing is provided. Results show that the method of measuring potential drop along casing is one of the most reliable methods for determining the value of protective current.

• Journal of Environmental Science International
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• v.20 no.8
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• pp.1049-1059
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• 2011

This paper examines the effects of the partial solar eclipse of 22 July 2009 across the Korean peninsular on surface temperature and ozone concentrations in over the Busan metropolitan region (BMR). The observed data in the BMR demonstrated that the solar eclipse phenomenon clearly affects the surface ozone concentration as well as the air temperature. The decrease in temperature ranging from 1.2 to $5.4^{\circ}C$ was observed at 11 meteorological sites during the eclipse as a consequence of the solar radiation decrease. A large temperature drop exceeding $4^{\circ}C$ was observed at most area (8 sites) of the BMR. Significant ozone drop (18~29 ppb) was also observed during the eclipse mainly due to the decreased efficiency of the photochemical ozone formation. The ozone concentration started to decrease at approximately 1 to 2 hours after the event and reached its minimum value for a half hour to 2 hours after maximum eclipse. The rate of ozone fall ranged between 0.18 and 0.49 ppb/min. The comparison between ozone measurements and the expected values derived from the fitted curve analysis showed that the maximum drop in ozone concentrations occurred at noon or 1 PM and was pronounced at industrial areas.

• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.1059-1067
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• 2006

In order to develop a compact evaporator, experiments that show characteristics of evaporating heat transfer and pressure drop in the helically coiled minichannel were performed in our previous research. This study was focused on the performance analysis of helically coiled heat exchangers with circular minichannels with an inner diameter=1.0 mm. The working fluid was R-22, and the properties of R-22 were estimated using the REFPROP program. Numerical simulation was performed to compare results with the experimental results of the helically coiled heat exchanger. As the heat transfer rate and pressure drop were calculated at the micro segment of the branch channels, the performance of the evaporator was evaluated. The following conclusions were obtained through the numerical simulations of the helically coiled heat exchanger. It showed good performance when the flow rate of each branch channels was suitable to heat load of air-side. The numerical simulation value agreed with experimental results within ${\pm}15%$. In this study, a numerical simulation program was developed to estimate the performance of a helically coiled evaporator. And, an optimum helically coiled minichannels evaporator was designed.

• Journal of IKEEE
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• v.24 no.2
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• pp.598-603
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• 2020

In this paper present a Low Drop-Out(LDO) regulator that improves load transient characteristics due to the push-pull pass transistor structure is proposed. Improved load over the existing LDO regulator by improving the overshoot and undershoot entering the voltage line by adding the proposed push-pull circuit between the output stage of the error amplifier inside the LDO regulator and the gate stage of the pass transistor and the push-pull circuit at the output stage. It has a delta voltage value of transient characteristics. The proposed LDO structure was analyzed in Samsung 0.13um process using Cadence's Virtuoso, Spectre simulator.