• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.644-649
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• 2006

This paper presents a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor $(k_p\;k_{15})$ becomes effective rather than the transverse mode coupling factor $(k_{31})$. ANSYS finite element code was used to analyze transformer behavior and to optimize electrode and poling configurations. The voltage step-up ratio of the proposed transformer has been markedly improved in comparison with that of the equivalent rectangular(Rosen) type. A single layer prototype transformer, $20\sim30mm$ in diameter and $1.0\sim3.5mm$ thick, was fabricated, such as step-up ratio, power transformation efficiency, and temperature were measured. While the transformer was driving a Cold Cathode Fluorescent Lamp(CCFL), the temperature field of the transformer was also observed.

• Proceedings of the Korea Society of Poultry Science Conference
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• 1999.11a
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• pp.11-33
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• 1999

This study was conducted to determine the embryonic stages for the isolation of the highest number of PGCs and to improve PGCs enrichment method. The primordial germ cells(PGCs) from different sources of chick embryos were isolated. The embryonic stage having the highest number of PGCs from each sources was selected ; 1-day-old embryos for germinal crescent (stage 6-8), 2.5-day-old embryos for blood (stage 17-18) and 5.5-day-old embryos for gonad (stage 27-28). The number of PGCs from one embryonic germinal crescent, blood and gonad was about 87$\pm$1.8, 103$\pm$4.0, and 932$\pm$10.9, respectively. The viability of PGCs after Ficoll from each sources was similar, showing approximately 70%. the PGCs enrichment method was improved using Ficoll density gradient centrifugation. After this step the purity of PGCs from germinal crescent, blood, and gonad was 45$\pm$9.10%, 85$\pm$1.18%, and 86$\pm$0.19%, respectively. Also, PGCs were picked up by mouth pipette to improve the purity. This improved method for the separation of PGCs from different sources will serve as a useful too to preserve the foundation stocks of poultry and to produce germline chimeras.

• Wind and Structures
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• v.29 no.4
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• pp.225-234
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• 2019

Conductor galloping is a common disaster for the transmission lines. Among the existing analytical methods, the wind tunnel test is highlighted as the most effective approach to obtain the aerodynamic coefficients. In this paper, the aerodynamic coefficients of 12 conductor models covered with the crescent-shaped ice, which were fabricated considering the surface roughness of the iced conductor, were obtained based on the wind tunnel test. The influence of the Reynolds number and the shape parameter ${\beta}$, defined as the ratio of ice thickness to the diameter, were investigated. In addition, the effect of surface roughness of the iced conductor was discussed. Subsequently, unsteady areas of conductor galloping were calculated according to the Den Hartog criterion and the Nigol criterion. The results indicate that the aerodynamic coefficients of iced conductors change sharply at the attack angles of $20^{\circ}$ and $170^{\circ}$ with the increase of ${\beta}$. The surface roughness of iced conductors changed the range of attack angle, which was influenced by the increase of the Reynolds number. The experimental results can provide insights for preventing and controlling galloping.

• Advances in Computational Design
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• v.6 no.1
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• pp.1-13
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• 2021

Failure of a Multi-storeyed reinforced concrete framed structure occurs when a primary vertical structural component is isolated or made fragile, due to artificial or natural hazards. Load carried by vertical component (column) is transferred to neighbouring columns in the structure, if the neighbouring column is incompetent of holding the extra load, this leads to the progressive failure of neighbouring members and finally to the failure of partial or whole structure. The collapsing system frequently seeks alternative load path in order to stay alive. One of the imperative features of collapse is that the final damage is not relative to the initial damage. In this paper, the effect on the column and beam adjacent to statically removed vertical element in terms of axial force, shear force and bending moment is investigated. Using Alternate load path method, numerical modelling of two dimensional one bay, two bay with variation in storey heights are analysed with FE model in order to obtain better understanding of failure mechanism of multi-storeyed reinforced concrete framed structure. The results indicate that the corner column is more susceptible to progressive collapse when compared to middle column, using this simplified methodology one can easily predict how the structure can be made to stay alive in case of sudden failure of any horizontal or vertical structural element before designing.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.149-155
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• 1997

We have successfully grown colorless and transparent Rb-doped potassium niobate (KRN) single crystals using the top seeded solution growth(TSSG) technique. In our crystal growth experiments, the Rb doping concentrations within the melt range from 2-15 mol% relative to that of Nb$_2$O5. Atomic absorption measurements indicate that the Rb content in the KRN solid solution is rather low; the Rb segregation coefficient is found to be on the order of 0.05. It is believed that this is due to the relatively much larger Rb+ ionic radius compared to that of K+, rendering it more difficult for Rb to replace K in the KNbO$_3$(KN) host lattice. Preliminary single-pass second harmonic generation (SHG) experimental results indicate that there exists marginal improvement in the phase-matching temperature tolerance of KRN compared to that of pure Kn single crystals.

• Asian-Australasian Journal of Animal Sciences
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• v.7 no.4
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• pp.459-466
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• 1994

Primordial germ cells (PGCs) in aves are the progenitor cells for the gametes. These cells first appear in the epiblast (Eyal-Giladi et al.. 1981). Then translocate and concentrate to endoderm of germinal crescent area in the junction of the area opaca and area pellucida lateral to the primitive streak in stage 4 through 7. They separate from the endoderm, temporarily circulate via the blood vascular system, leave the blood vessels, and finally settle down in the gonadal anlagen at stage 20-24 where they rapidly proliferate to form germ cells. Recently, several attempts have been made to introduce foreign gene into the avian genome to form a transgenic chicken. The stem cells most readily available as vehicles for genetic manipulation of germline in avian species are the PGCs. PGCs have recently been manipulated genetically and used successfully as a vector for gene transfer.

• The International Journal of Costume Culture
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• v.6 no.2
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• pp.69-82
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• 2003

The Scythians had a veritable passion for adornment, delighting in decorating themselves no less than their horses and belongings. Their love of jewellery was expressed at every turn. The most magnificent pieces naturally come from the royal tombs. In the area of the neck and chest the Scythian had a massive gold Torques, a symbol of power, made of gold, turquoise, cornelian coral and even amber. The entire surface of the torque, like that of many of the other artefacts, is decorated with depictions of animals. Scythian Torques are worn with the decorative terminals to the front. It was put a Torque on, grasped both terminals and placed the opening at the back of the neck. It is possible the Torque signified its wearer's religious leadership responsibilities. Scythian Torques were divided into several types according to the shape, Torque with Terminal style, Spiral style, Layers style, Crown style, Crescent-shaped pectoral style.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1951-1953
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• 2005

This paper present a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor $(k_p,\;k_{15})$ becomes effective rather than the transverse mode coupling factor ($k_{31}$). A single layer prototype transformer, 26[mm] in diameter and $1.5{\sim}4.0[mm]$ thick, was fabricated, such as step-up ratio, power transformation efficiency and temperature were measured.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.475-478
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• 2005

Calculation of wear depth with regard to the wear topology is peformed numerically Four typical wear topology, that is round, crescent, flat, and diamond types are adopted to represent the configuration of wear volume. Diamond and flat types are the most severe topology for wear depth history, whereas round and crescent types have small increasing rate of wear depth to the wear volume. Based on this study we can guess that the most severe wear phenomena happens to be upper side of U-tubes in the KSNP SG, because flat or diamond wear will be generated by the wearing motion between tubes and diagonal, vertical, horizontal strips. The misalignment of tube at the stage of manufacturing or distortion of upper structure due to the thermal expansion or vibration of upper structure such as diagonal, vertical, and horizontal strips will be one of the main causes of flat or diamond wear.

• Journal of Sericultural and Entomological Science
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• v.43 no.2
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• pp.67-76
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• 2001

The "crescent-egg" a new spontaneous mutant was detected in a white egg strain k37. Studies were carried out the linkage analysis, to investigate phenotypic characteristics and biochemical analysis of haemolymph and ovarian protein. The mutant, ore was independent from 20 linkage groups P(2), Ze(3),L(4), oc(5), sn8), Ia(9), w-1(10), K(11), ch(13), U(14), bl(15), cts(16), bts(17), mln(18), nb(19), oh(20),Lan(21), or(22), tub(23) and Xan(27). The fertilization, hatchability and larval growth were not different from the those of normal eggs. The content and composition of yolk protein were similared to normal eggs. Scanning electron microscopy revealed the areal specific structure in dorsal region of egg-shell of cre mutant. Analysis of chorion protein by isoelectrofocusing(IEF), was resolved no difference in the composite of the chorion protein. We conclude that the egg mutant ere is expressed only in the egg-shape formation and region specific determination.