• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.5
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• pp.459-467
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• 2012

In this work, the configuration of a haptic gripper featuring magnetorheological(MR) brakes is proposed and an optimal design of the MR brakes for the haptic griper is performed considering the required braking torque, the uncontrollable torque(zero-field friction torque) and mass of the brakes. Several configurations of MR brake is proposed such as disc-type, serpentine-type and hybrid-type. After the configurations of the MR brakes are proposed, braking torque of the brakes is analyzed based on Bingham rheological model of the MR fluid. The zero-field friction torque of the MR brakes is also analyzed. An optimization procedure based on finite element analysis integrated with an optimization toolbox is developed for the MR brakes. The purpose of the optimal design is to find optimal geometric dimensions of the MR brake structure that can produce the required braking torque and minimize the mass of the MR brakes. In addition, the uncontrollable torque of the MR brakes is constrained to be much smaller than the required braking torque. Based on the developed optimization procedure, optimal solution of the proposed MR brakes are achieved and the best MR brake is determined. The working performance of the optimized MR brake is then investigated.

• International Journal of Costume and Fashion
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• v.5 no.2
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• pp.55-67
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• 2005

The purpose of this study is to document an unidentified velvet fabric which is located in the Museum. The investigation was conducted by analyzing color, weaving technique. pattern of the study object. To identify the origin of the object, many references about color trends, construction methods and patterns were accessed. Two comparative objects which were dating from 1600 to 1699 in the Museum of F.I.T. were selected since they are similar to the study object. The results of this study can be summarized as follows; (1) The type of this study object is 'cut and voided velvet'. It is obtained establishing the motif as areas of cut pile so as to form a pattern, while leaving other areas of the grounded weave without pile. Two flowers and two tulips with S curved stems are composed as one unit in the vertical direction. (2) The colors used in this study object. which are ivory, smoke blue, medium orange, and yellow. are part of a new trend color in the $17^{th}$ century. (3) The vertical undulating stripe patterns are also of significance in this fabric. They seemed to be contemporary with the serpentine line which was common since the $15^{th}$ century and the vertical stripes pattern which appeared from the $16^{th}$ century. (4) The stylized tulip patterns of this study object began to appear in the early $17^{th}$ century. The stems and leaves of this patterns are less sinuous than the floral motifs of the later $17^{th}$ century. Therefore, the study object is dated to early in $17^{th}$ century because of the color combination. stripes. stylized tulips, leaves. and stems are showing the characteristics of this period.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.249-261
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• 2012

Phlogopite-bearing orthopyroxenite occurs in Andong ultramafic complex in a planar body of about 1 meter thick, and consists mostly of coarse subhedral to euhedral orthopyroxene crystals. Minor minerals are clinopyroxene, phlogopite, and plagioclase with trace chromian spinel, pentlandite, apatite, and zircon. Clinopyroxene occurs as either exolution lamella or interstitial fillings with phlogopite and plagioclase. Electron microprobe analysis showed that orthopyroxenes are entatite, while clinopyroxenes are diopside with little chemical variation through samples. Hydrous alteration resulted in the formation of talc, amphibole, and serpentine from orthopyroxene, clinopyroxene, and plagioclase, respectively. The orthopyroxenite was probably formed by the fractional crystallization of the ultramafic magma. Radiogenic dating of phlogopite and zircon of the orthopyroxenite would reveal the age of the Andong ultramafic complex.

• Journal of Embryo Transfer
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• v.24 no.2
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• pp.109-113
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• 2009

Serial ultrasonography was performed to measure the normal appearance of uterine during estrous cycle and to determine whether the unterine appearance was related to the sex hormone, progesterone and estrogen. The uterine appearances, shape, diameter and echogenicity were daily monitored with ultrasonography in 9 Miniature Schnauzer dogs undergoing II estrous cycles. During proestrus and estrous, the uterus became hypoechoic but developed hyperechoic luminal echo. In the longitudinal view, the shape of the uterus occasionally changed from rectangular to coiled or serpentine, compared to other stages of the cycle. The diameter of the uterus during proestrus and estrous was larger (range: 0.60${\sim}$0.86 mm) than other stages (range: 0.48${\sim}$0.62 mm) of the cycle. The rising estrogen concentrations (range: 14.51${\sim}$16.86 pg/ml) in plasma during proestrus correlated with changes in the uterus (p<0.05). Progesterone concentrations were 0.08${\sim}$0.15 ng/ml at the onset of proestrus, but rose 1.06${\sim}$1.26 ng/ml at the end of proestrus. There was no relation to progesterone concentration from onset of estrus (p>0.05). There was dramatical changes in normal uterus and sex hormone during estrous cycle. Especially, the appearance, shape and diameter of uterus were related to plasma estrogen concentration during proestrus, correlated with other stages of the cycle.

• Journal of Digital Convergence
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• v.14 no.6
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• pp.245-251
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• 2016

A numerical model is developed to predict distributions of current density and temperature. Also the complete fuel cell performances were compared. In this study the effect of flow field design and flow direction on current density and temperature distribution as well as full cell performance. The complete three-dimensional Navier-Stokes equations were solved with convergence of electro-chemical reactions terms. In this paper, the two different flow field design were simulated, straight channel and rectangular serpentine flow channel, which is commonly used. The effect of flow direction, co-flow and counter-flow, was also analyzed. The current density and temperature is higher with abundant oxygen not fuel. Also, temperature distribution was able to be drawn by using computer simulation. In this paper, the relationship among flow pattern, flow field design and current denstity distribution.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.2
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• pp.85-92
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• 2009

Polymer electrolyte membrane (PEM) fuel cells are a promising technology for short-term power generation required in residential and automobile applications. Proper management of water has been found to be essential for improving the performance and durability of PEM fuel cells. This study investigated the liquid water exhaust capabilities of various flow channels having different geometries and surface properties. Three-pass serpentine flow fields were prepared by patterning channels of 1 mm or 2 mm width onto hydrophilic Acrylic plates or hydrophobic Teflon plates, and the behaviors of liquid water in those flow channels were experimentally visualized. Computational fluid dynamics (CFD) simulations were also conducted to quantitatively assess the liquid water exhaust capabilities of flow channels for PEM fuel cells. Numerical results showed that hydrophobic flow channels have better liquid water exhaust capabilities than hydrophilic flow channels. Flow channels with curved corners showed less droplet stagnation than the channels with sharp corners. It was also found that a smaller width is desirable for hydrophobic flow channels while a larger width is desirable for hydrophilic ones. The above results were explained as being due to the different droplet morphologies in hydrophobic and hydrophilic channels.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.2
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• pp.169-174
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• 2007

In process of reinforced concrete (RC) box structure, the heat of hydration may cause serious thermal cracking. This paper reports results of hydration heat control in mass concrete using the oscillating heat pipe. There were three RC box molds ($1.2m{\times}1.8m{\times}2.4m$) which were different from each other. One was not equipped with pulsating heat pipe. The others were equipped with pulsating heat pipe. All of them were cooled with natural air convection. The pulsating heat pipe was composed of 10 turns of serpentine type copper pipe whose outer and inner diameters were 4 and 2.8 mm respectively. The working fluid was R-22 and charging ratio was 40% by volume. The temperature of the concrete core was approximately $55^{\circ}C$ in the winter without pulsating heat pipe. For a concrete with pulsating heat pipe, however, the temperature difference with the outdoor one reduced up to $12^{\circ}C$. The index figure of crack was varied from 0.75 to 1.38.

• Journal of Korean Society of Forest Science
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• v.96 no.2
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• pp.178-182
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• 2007

Rauvolfia serpentina (L.) Benth. ex Kurz is a medicinal plant and an endangered tropical rainforest plant species. Since the field cultivation that aims to fulfill the industrial needs is never accomplished, tissue culture appears to be the most feasible way to improve the quality and quantity of R. serpentina. This experiment used two kinds of explants (roots and shoots) to induce optimal root formation in different combinations of auxin and photoperiod. Each explants exhibited different responses on given treatments. Differentiated root could be produced from explants cultured in IBA 20 mg/L with and without light. The highest number of roots, root length and root weight induced from shoot explants were effective on MS medium containing IBA 20 mg/L and incubated under dark condition, while highest total weight (callus and root) from root explants cultured on MS medium supplemented 10 mg/L IBA and 10 mg/L NAA and incubated under day length (11/13 hr). The root induced from shoot explants produced the highest major alkaloid content. The highest content of ajmaline (2.17 ppm fresh weight) and reserpine (1.30 ppm fresh weight) were observed in shoot explants cultured in MS medium containing combination of IBA 10 mg/L and NAA 10 mg/L and incubated under dark condition, yohimbine (1.47 ppm fresh weight) was in the shoot explants cultured in MS medium containing NAA 20 mg/L and incubated under day length, while serpentine was absent.

• Economic and Environmental Geology
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• v.5 no.4
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• pp.221-229
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• 1972

Through the series of study on the above subjects, the following were founded. 1. Soluble silica in paddy top-soil (xppm) and maxium possible yield (y) is expressed as following equatic $y=63.97+0.425x-0.00114x^2$ It is known that soluble silica in paddy top-soil in South Korea is limited as 130ppm. 2. Gnder the present Korean condition 90% of paddy-top-soil is estimated to be short in available silica content and the country average to only 78ppm. 3. The total area of Korean paddy-top-soil is about 1,036,710 ha. All requirements of wollastonite in South Korea estimated from the equation $Y=0.94-0.033{\times}$are about 2 million M/T 4. Silicates fertilizer minerals are Bentonite, Zeolite, Wollastonite, Serpentine, and Chlorite. But Wollastonite is most economic and can be supplied to using Korea. 5. Wollastonite is formed in contact metomorphic deposits. Limestone is the country rock of wollastonite. Limestone in Korea is in Ryunchcon system, (Pre-cambrian) Okcheon system, (unknown), Great limestone series (paleozoic), Hongjum series (Paleozoic) and Kyungsang system (mesozoic) so that the zones of these limestone and igneous rock are the possible area which wollastonite can be produced. 6. According to the published geologic map (scale 1/5000), about 25 provinces will be possible area which wollastonite can be produced. In future, I believe that many possible area will be increased. 7. According to this survey at Danyang, total wollastonite resources are about 179,000 M/T and average of soluble $SiO_2$ is 29.84%. 8. According to this survey at Daijeon, total resources are about 57,600 M/T and average of soluble $SiO_2$ is 21.53%. 9. Total wollastonite resources including Danyang, Yangduk, and Daijeon are about 1,172,200 M/T. Considering possible resources, it will be over 20 million M/T and I can say that it is possible to be supply for a score.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1475-1482
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• 2009

In this paper, a computer simulation is developed for isotachophoretic protein separation in a serpentine micro channel for optimal lab on a chip design using 2D Finite Element Method. This 2D ITP model is composed of 5 components such as hydrochloric acid as Leader, caproic acid as terminator, acetic acid and benzoic acid as two proteins, and histindine as background electrolyte. The computer model is based on mass conservation equation for 5 components, charge conservation equation for electric potential, and electro neutrality condition for pH calculation. For the validation of the 2D spatial ITP model, the results are compared with the Simul5 developed by Bohuslav Gas Group. The simulation results are in a good agreement in a ID planar channel. This proves the precision of our model. The 2Dproteinseparation is conducted in a 2D curved channel for Lab on a chip design and dispersions of proteins are revealed during the electrophoretic process in a curved shape.