• Journal of Advanced Marine Engineering and Technology
• /
• v.18 no.4
• /
• pp.43-52
• /
• 1994

I investigated experomentally the spray characteristics to the operating conditions and the shapes of internal mixing twin fluid atomizer. The wide variations of air per liquid ratio are conducted to predit the influences of the Sauter mean diameter(SMD), spray angle, distribution of drop size, the flowing condition of gas and length, flowing, area of gas and liquid, and diameter, number and place of the orifice. In this experiment, air per liquid raio, mixing chamber length per diameter, orifice diameter, and the flowing area ratio of gas and fluid influences greatly on SMD, spray angle, distribution of drop size and intermittent fluctuation region.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.4
• /
• pp.695-702
• /
• 2001

In this paper, the drop/impact simulation for a mobile phone has been carried out with the explicit code LS-DYNA and its validation has been experimentally verified. The small size of this kind of electronics products makes it time-consuming, and difficult to conduct drop tests to detect the failure mechanism and identify their drop behaviors. Strict drop/impact performance criteria of such hand held electronic products as mobile phones play an important role in their design because these products must withstand both normal and unexpected shock. Usually, the product durability on drop impact depends on designers experience. The present reliable methodology of drop/impact simulation provides an efficient and powerful vehicle to improve the design quality and reduce the design period.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.12
• /
• pp.4053-4061
• /
• 1996

Internal flow characteristics within Y-jet atomizers and the local drop size distribution and cross-sectional averaged drop size at the outside were investigated with the liquid and air injection pressures, mixing port length of atomizers, and the liquid properties taken as parameters. To examine the effect of the liquid viscosity, glycerin-water mixtures were used in this study. The liquid viscosity plays only a minor role in determining the internal flow pattern and the spatial distribution shape of drops, but the drop sizes themselves generally increase with increasing of the liquid viscosity. An empirical correlation for the liquid discharge coefficient at the liquid port was deduced from the experimental results; the liquid discharge coefficient strongly depends on the liquid flow area at the mixing point which is proportional to the local volumetric quality(.betha.$_{Y}$), and the volumetric quality was included in the correlation. Regardless of the value of the liquid viscosity, the compressible flow through the gas port was well represented by the polytropic expansion process(k=1.2), and the mixing point pressure could be simply correlated to the aspect ratio( $l_{m}$/ $d_{m}$) of the mixing port and the air/liquid mass flow rate ratio( $W_{g}$/ $W_{f}$) as reported in the previous study.udy.udy.y.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.48 no.1
• /
• pp.66-81
• /
• 2024

This study analyzed body shape changes over time by comparing Size Korea's data on 50-84-year-old women from 2020 to 2021 with the same data from 2003 to 2004. In addition, the subjects of these data were divided into drop-types and also upper-body-drop-types with the body measurements for each type compared. The results showed that elderly women had grown 3-4 cm taller over the last 20 years, but the length of 'neck shoulder point to breast point' had become shorter; the bust and waist circumferences were smaller, but the thigh circumference was larger. In the body-drop type, the bust circumference, waist circumference, and waist circumference(Omphalion) increased by about 4-6cm in the order of N-type < H-type < Y-type indicating that the sideline slope of the torso must be differentiated. The upper-body-drop-type showed a 1-cm difference in height and bust circumference, but a 4 to 5-cm difference in waist circumference. In addition, thick-waist subjects aged 70 or older were classified into separate body types with the results showing that their waist circumference was greater than their breast circumference, signifying the need for different top patterns.

• Journal of the Ergonomics Society of Korea
• /
• v.33 no.5
• /
• pp.337-354
• /
• 2014

Objective: The purpose of this study was to examine the various sizing systems and specified anthropometric data as well as the fit issues used today. Background: A standard sizing system for clothes is a system that is developed based on body shape and size classifications method. To develop an efficient sizing system, we have to classify the database from the majority of the samples. Method: The method of this paper deals with the secular trend of height spanning from 1997 to 2010 along with the morphological feature patterns for Koreans. It also investigates the comparison of the growth pattern between male and female and the body shape classification according to the drop values based on the anthropometric data samples of KATS taken from the 2010 surveys in order to develop and define the new guidelines for the size designation systems of clothes. Results: The results are classified with body size and shape categories according to the drop values by age and sex in order to develop the new guidelines for the size designation systems based on these body dimensions from the analyzed anthropometric database. Conclusion: These new guidelines for the size designation system will eliminate the confusion that currently exists among countries and individual apparel designers. Application: The adopted standards could be used to compare the sizing systems worldwide.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.20 no.5
• /
• pp.559-563
• /
• 2011

Drop impact reliability assessment of solder joints on the flip chip is one of the critical issues for micro system packaging. Our previous researches have been showing that new solder ball compositions of Sn-3.0Ag-0.5Cu has better mechanical reliability than Sn-1.0Ag-0.5Cu. In this paper, dynamic reliability analysis using Finite Element Analysis (FEA) is carried out to assess the factors affecting flip chip in drop simulation. The design parameters are size and thickness of chip, and size, pitch and array of solder ball with composition of Sn1.0Ag0.5Cu. The board systems by JEDEC standard including 15 chips, solder balls and PCB are modeled with various design parameter combinations, and through these simulations, maximum yield stress and strain at each chip are shown at the solder balls. It is found that larger chip size, smaller chip array, smaller ball diameter, larger pitch, and larger chip thickness have bad effect on maximum yield stress and strain at solder ball of each chip.

• Transactions of the Korean hydrogen and new energy society
• /
• v.15 no.1
• /
• pp.72-81
• /
• 2004

Study on the analysis of sodium spray fire using Gaussian drop size distribution, which redistributes a droplet spectrum with given mean diameter if its size classes with critical diameter(D>8mm) occur, was carried out. In this case, the oversized droplets were reduced to a stable diameter. Results calculated by the code using Gaussian drop size distribution were in better agreement with AI experimental results than those of NACOM and SPRAY code. The effect of variance on pressure in the test cell appeared greatly by introducing Gaussian function, which could represent various sodium droplet size distribution. The increase of the variance with mean droplet size resulted had an important effect upon the pressure in the test cell.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.14 no.5
• /
• pp.391-397
• /
• 2002

Pressure drop were experimentally investigated for ice slurry flowing in the acrylic pipes with inner diameter of 24 mm. Ice slurry was made from 6.5% ethylene glycol-water solution, and the pipes is consisted of horizontal, vertical (upward and downward) and $90^{\circ}$ elbow pipe. The ice Packing factor (IPF) and the flow rate of the experiments were varied from 0 to 30% and from 5 to 70kg/min respectively The measured pressure drop in various pipe positions were compared with those for the solution flow (IPF=0). The pressure drop was larder than that for solution flows as the IPF increased when the flow rate was low or very high. Sharp increases in pressure drop were observed for the cases when IPF is more than 70% in horizontal and vertical pipes, whereas the pressure drop increased with the IPF simultaneously in an elbow pipe.

• The Research Journal of the Costume Culture
• /
• v.20 no.4
• /
• pp.529-534
• /
• 2012

An analysis of adult women's somatotypes classified by drop values can provide important preliminary data in determining standard clothing sizes for mass production of ready-made clothes. This is because the values are based on measurements of girth, which is essential information in the size-setting process. Adult women's body types are classified according to drop values in a standard clothing size system adopted by Korea and several other countries. This study aims to identify somatotype characteristics of adult women aged 20 to 69 by using five types of drop values: bust-waist, hip-waist, hip-bust, abdomen-waist, and hip-abdomen. Statistical cluster analysis of collected data revealed four somatotypes among adult women. Type R, with a developed lower body, accounted for 36.6%, and its bodyline was found to be closest to the average adult woman. Type X, constituting 25.4%, had the curviest contours of all and relatively large hip measurements, with the thinnest figure. Flat abdomen and hips characterized type Y, which accounted for 18.9%. Lastly, 19.0% fell into type H, the most obese figure, in which abdomen girth exceeded hip measurements. Since type H has excess fat deposits in the abdomen, not only hip measurements but also abdomen girth should be considered when designing top longer than torso-length and bottoms.

• Korean Journal of Human Ecology
• /
• v.7 no.2
• /
• pp.63-73
• /
• 1998

To get well-fitted ready-made clothings with beautiful silhouettes, it's better to classify body forms into several forms and to assign sizing within each form than to grade just based on body size regardless of body styles. This study illucidated the importance of drop value in the results of surveying the current values of sizing and grading. Therefore, it's meaningful to get the classification of body form with appropriate distribution of drop values of the body, and the distribution of drop value and the frequency of each form is very helpful to name the combined sizing or coverage of ready-made clothes. This study aimed at classifying body forms with various drop values using multivariate analysis for sizing and grading. Factor analysis and cluster analysis were done using measured values from 346 unmarried women. The results are as follows: 1. The factor which explains body forms was obtained by factor analysis, and the representative major 18 items which have important roles in classifying body forms were selected among the measured values with high factor loading and communality. 2. The body forms were classified into 8 groups based on the charateristics, frequencies and distributions of them obtained from cluster analysis. 3. Each classified body form showed conspicuous difference in drop value and the difference of body form mainly resulted from the difference between waist and hip rather than the difference between bust circumference and waist in Korean unmarried women.