• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.613-619
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• 2022

The extended Maxwell-Wagner polarization model is employed to describe the ER(Electrorheological) behavior of bi-dispersed ER suspensions, and solutions to the equation of motion are obtained by dynamic simulation. Under the same particle volume fraction, it is found that the dynamic yield stresses of uniform size suspensions do not depend on the particle size. Compared with uniform size suspensions, the dynamic yield stress is reduced for ER fluids consisting of two kinds of particles with different sizes. Compared with the dynamic yield stress behavior, for ${\dot{\gamma}}^*$≧0.01 the shear stress shows different behaviors depending on the particle sizes and the raio of different size particles. The simulation results show the nonlinear ER behavior (∆_𝛕 ∝ Eⁿ, n ≈ 1.55) of the conducting particle ER suspensions.

• Geomechanics and Engineering
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• v.28 no.5
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• pp.521-529
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• 2022

This research work deals with the development of air pluviation method for preparing uniform sand specimens for conducting large scale laboratory testing. Simulating real field conditions and to get reliable results, air pluviation method is highly desirable. This paper presents a special technique called air pluviation or sand raining technique for achieving uniform relative density. The apparatus is accompanied by a hopper, shutters with different orifice sizes and numbers and set of sieves. Before using this apparatus, calibration curves are drawn for relative density against different height of fall (H) and shutter sizes. From these calibration curves, corresponding to the desired relative density of 60%, the shutter size of 13mm and height of fall of 457.2 mm, are selected and maintained throughout the pluviation process. The density obtained from the mobile pluviator is then verified using the Dynamic Cone Penetrometer (DCP) test where the soil is poured in the box using defined shutter size and fall height. The results obtained from the DCP test are averaged as 60±0.5 which was desirable. The mobile pluviator used in this research is also capable of obtaining relative densities up to 90%. The instrument is validated using experimental and numerical approach. In numerical study, Plaxis 3D software is used in which the soil mass is defined by 10-Node tetrahedral elements and 6-Node plate is used to simulate plate behavior in the validation phase. The results obtained from numerical approach were compared with that of experimental one which showed very close correlation.

• Journal of Fashion Business
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• v.24 no.4
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• pp.48-62
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• 2020

Originating in South Korea, Taekwondo has been globally popular among individuals who desire to improve their health in a unique fashion. The Taekwondo uniform, one of the essential factors within the sport, needs to possess both functionality and size suitability to support dynamic movements within Taekwondo. This study investigated the development of patterns in Taekwondo uniforms by suggesting patterns that reflect physical suitability derived from appearance tests and movement functionality tests of the uniforms. More specifically, we selected a sample uniform and conducted a dressing test, which considered both the aesthetics and the functionality of the garment. Then, we considered size suitability, which allowed us to design practical Taekwondo uniform patterns that encompassed more variation in body sizes of both men and women. The result of the dressing test was that women's uniforms typically required more factors compared to men's uniforms due to women's relatively smaller physiques. Based on this result, we revised the pattern to also encompass the minor differences in uniforms between men and women. In the end, the Taekwondo uniforms for women required more modifications than those for men.

• Journal of Fashion Business
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• v.13 no.3
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• pp.25-39
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• 2009

This research attempts to analyze the physical characteristics of middle school girls and compare the product sizes and patterns of school uniform blouses by brand. And wearing tests were performed regarding the appearance of blouse by bland. The results are follows. The standard deviation for bust circumference and waist circumference of middle school girls measured in 2004 were showed extremely large difference among individuals compared to the previous results. While waist back length reached adult size by $2^{nd}$ grade high school, bishoulder length reached adult size by $2^{nd}$ grade middle school. And girls after $2^{nd}$ grade middle school had their depth and breadth of bust, underbust circumference and bust circumference growing proportionally. These results need to be reflected in producing a pattern drafting for middle schoolers. By comparing wearing test results on appearance, it was shown that in terms of ease of bust circumference, the expert group evaluated brand with less ease as not having adequate ease compared to brand, while the middle schooler group evaluated as having sufficient ease. The front silhouette also showed same results. This reflects the preference for appearance by the middle schooler group, which is a factor to be considered during pattern drafting of school uniform blouse.

• Journal of the Korean Society of Costume
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• v.62 no.4
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• pp.207-217
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• 2012

The function of the school uniform is to represent the role of a student and also to restrict the scope of action for the student. Many students wear school uniforms for the most of their daily life. So the school uniform is very important for students during the school days. The purpose of this study was to suggest the fundamental information for the development of the school uniform design based on actual wearing conditions and preferred designs. Photos of school uniforms of 61 girls' high schools in Seoul were analyzed. Surveys of actual wearing conditions and preferred designs were investigated. The major conclusions of the study were as the following: 1. Most of the high school girls wore the uniform jackets that had tailored collars, were single breasted, slightly fitted, and that have a medium length between the waistline and hipline. Many students wore skirts with various pleats and knee length. Many school uniforms were navy blue and grey. 2. Many students bought ready-to-wear school uniforms from agencies with their parents. When they bought the school uniforms, they tried it on and confirmed the sizes on their own. However, since they didn't know the size systems, and they had to repair the size and design of the school uniforms. Students felt uncomfortable with how the shoulders and sleeves fit. 3. Uniform Jackets with tailored collars, single breasted, slightly fitted, and a short waistline length were preferred. Pleats skirts with knee length or upper-knee length were preferred. Navy blue and grey colors, and elastic fabrics were preferred. 4. When comparing the actual wearing conditions and preferred designs of school uniforms, there were a few differences in styles, but overall, students preferred shorter lengths of jackets and skirts. It is considered to reflect the fashion trends and the students' pursuit for beauty.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1583-1586
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• 2011

Silver nanoparticles (<10 nm) were prepared in ultrasonic vibration-induced nanodroplets of isopropyl alcohol (IPA) in combination with hydrophobic room temperature ionic liquids (RTILs). The Ag-precursor used were silver (I) complex, Ag$_2$(ehac)$_2$(eha)$_2$ (ehac = 2-ethylhexylammonium carbamate; eha = 2-ethylhexylamine), in IPA, while 1-butyl-3-methylimidazolium-based ionic liquids bearing $SbF_6^-$, $PF_6^-$ and $NTf_2^-$ as counter anions were used as RTILs. During sonication for 10-90 min at room temperature, uniform silver nanoparticles with mean sizes of 2 to 8 nm were rapidly synthesized. Transmission electron micrographs also confirmed that silver nanoparticles have a spherical shape and diverse sizes depending on the reaction time (10-90 min).

• Journal of the Korean Society of Costume
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• v.54 no.3
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• pp.65-71
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• 2004

Surgical operating gowns are worn by doctors and nurses in operating theater to address dual function of preventing transfer microorganisms like bacteria and body fluids from the operating staffs to patients. and also from patients to staff. They must allow necessary mobility without rubbing and must resist tearing. These gown must be designed to fit a diversity of body shapes and sizes with a limited range of sizes as hospitals will stock limited quantities. Also they must proper in various operating situations. In order to suggest improving design features of surgical gowns, it has been done to analyze current situation of medical uniform manufacturing and wearing. Surgical gown were made with plain fabric of cotton 100% and had a little size system without sexual division. Many doctors were unsatisfied with surgical gown size and wearing comfort. Surgical operating gowns need continuos research for new material and design as surgical situation, and new sizing system.

• Journal of Communications and Networks
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• v.14 no.4
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• pp.443-450
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• 2012

As for cluster-based wireless sensor networks (WSNs), cluster lifetime is one of the most important subjects in recent researches. Besides reducing the energy consumptions of the clusters, it is necessary to make the clusters achieve equal lifetimes so that the whole network can survive longer. In this paper, we focus on the cluster lifetimes in multi-hop WSNs with cooperative multi-input single-output scheme. With a simplified model of multi-hop WSNs, we change the transmission schemes, the sizes and transmission distances of clusters to investigate their effects on the cluster lifetimes. Furthermore, linear and uniform data aggregations are considered in our model. As a result, we analyze the cluster lifetimes in different situations and discuss the requirements on the sizes and transmission distances of clusters for equal lifetimes.

• Journal of Industrial Technology
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• v.12
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• pp.51-59
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• 1992

In this paper, the technique to fabricate the optical fiber preforms by centrifuge was investigated, using silica particles of different sizes. The injection tube was designed to traverse axially so that uniform coaling of tiny silica particles onto the substrate tube can be certified. The deposition efficiencies and deposition rates of $SiO_2$ particles were measured to elucidate the effects of process variables such as rotation speed of rotor, aqueous flow rate, suspension concentration, binder concentration and overflow weir diameter. This study shows dearly the merit of this technique by enhancing abruptly the deposition rates and deposition efficiencies, comparing to the conventional processes for optical fiber preforms.

• International Journal of Safety
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• v.4 no.1
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• pp.18-22
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• 2005

A model was proposed for investigating the particle removal from suspension with particles of different sizes by deep-bed filtration, and the collection efficiency was predicted by computer simulation. Deposited particles on the pore surface may act as additional collector and reduce the pore size, which contribute to the improved collection efficiency with increase of deposition. Computer experiments for suspension of particles of three sizes and its equivalent size of mono particles were carried out and compared. The collection efficiency of suspension with poly-dispersed particles shows higher efficiency than that of suspension with mono-dispersed particles. Also the collection efficiency of smell particle of mixture is higher that that of same uniform size particles.