• Journal of Welding and Joining
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• v.11 no.4
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• pp.57-69
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• 1993

In the present study, the microstructure and Charpy V notch toughness of multipass $CO_2$ FCA weldment in three different heat inputs(1-3KJ/mm)were investigated. The weldments using two different domestic FCAW wires(AWS E71T-1 and E71T-5 equivalent) in C-Mn steel were chemically analysed. The following conclusions can be inferred. 1. T-1 wire Showed a stable arc transfer, less spatter and harsh, a better bead spreading and easy slag removal, whereas T-5 wire suffered from the arc stability, which tended to increase spatter and produce a more convex bead. 2.The microsturctures of the top beads of the weldments in three different heat inputs consisted of coarse-grained boundary ferrite and Widmanstatten ferrite side plate with increasing heat inputs. The modest fraction of acicular ferrite in the two wire weldments was observed in the 2KJ/mm heat input. 3.The fine-grained reheated zones of both welds consisted of a duplex microstructure of polygonal ferrite and second phases. 4. The basic flux weldment of T-5wires showed a higher Charpy impact property than that of T-1 wires because of a higher fraction of acicular ferrite in the weld microstructure.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.5
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• pp.250-257
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• 2006

It is well known that Grain-oriented electrical steel sheets have two dimensional magnetic properties according to the direction of exciting field such as non-linear phase difference between magnetic flux density and magnetic field intensity vectors, different iron loss and permeability even when an alternating magnetic field is applied. The measurement and application of the two dimensional magnetic properties of the Grain-oriented electrical steel sheets, therefore, are very important for the design and precise performance analysis of electric machines made of them. As the direction of exciting field changes, in this paper, the two dimensional magnetic properties of a Grain-oriented electrical steel sheet, i.e., non-linear B-H curves, phase difference between B and H, and iron loss characteristics, are measured using SST(Single Sheet Tester) which has two axes excitation. The measured results are presented in two ways: using $(B,\theta_B)$ method and using hysteresis loops along rolling and transverse directions, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.439-440
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• 2008

An inductive coupler, which feeds communication to the electric power transmission line, is required to establish Power Line Communication(PLC). The electro-magnetic property of magnetic core and design technology for coupler are very important to manufacture an inductive coupler for power transmission line. The magnetic core with superior electro-magnetic property was manufactured by using nano-crystalline alloy and an inductive coupler, which can operate at the maximum 2,000 A current, was designed and manufactured by establishment of current saturation, signal out winding, and electro-magnetic simulation in this study. Communication speed of 14 Mbps in 600 m communication distance of the real electric power transmission line was obtained by using the inductive coupler and application possibility of the inductive coupler for the electric power transmission line was certified.

• Wind and Structures
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• v.18 no.3
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• pp.281-294
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• 2014

There are several parameters affecting the response of industrial reinforced concrete (RC) chimneys, i.e., the severity of wind and earthquake loads acting to the structure, structural properties such as height and cross section of the chimney, the slenderness property of the structure etc. One of the most important parameter that should be considered while understanding the wind response of industrial RC chimneys is slenderness property. Although there is no certain definition for slenderness effect on these structures, some standards like ASCE-7 define slenderness from different aspects of the structural properties. In the first part of this study, general information about the definition of slenderness in the well-known standards and ten selected industrial RC chimneys are given. In the second part of the study, brief information about wind load standards that are used for calculating wind loads namely ACI 307/98, CICIND 2001, DIN 1056, TS 498 and Eurocode 1 is given. In the third part of the study, calculated wind loads for selected chimneys are represented. In the fourth part of this study, the internal forces obtained from load combinations that are applied to chimneys and some graphs presenting the effect of slenderness on chimneys are given. In the last part of the study, a conclusion and discussion part is taking place.

• Journal of the Korean Society for Heat Treatment
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• v.29 no.6
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• pp.277-283
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• 2016

The influences of cooling pressure of quenching process on the mechanical properties such as hardness, impact endurance and anti-thermal fatigue behaviour of STD61 steel were investigated. The specimens were heat-treated using a vacuum furnace in which they were austenitized at $1,030^{\circ}C$ for 1hour under the pressure of $10^{-3}$ torr and cooled with quenching gas of various pressure, i.e. 1, 2 and 6 bar. According to the observation on the specimens prepared with quenching from austenizing temperature, the mechanical properties of the samples with higher quenching pressure were better than those of prepared at lower quenching pressure. The samples prepared with high quenching pressure showed the more homogeneous microstructure with finer carbides. The size of carbides such as VC and (Fe, Cr)C in quenched specimens decreased with increasing gas quenching pressure. It is considered that the rapid cooling with pressure may restrict the formation and growth of carbide.

• Journal of the Korean Ceramic Society
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• v.42 no.5 s.276
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• pp.299-303
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• 2005

The crystal structure and ferroelectricity of the $(1-x)BiFeO_3\;(BF)-xPbTiO_3$ (PT) ceramic system with the addition of $DyFeO_3$ (DF) have been investigated for attaining a high temperature piezoelectric material. This study is focused on the relation between crystal structure and ferroelectric property with the addition of DF over the phase boundary in the (1-x)BF-xPT system. Hysteresis curves of polarization-electric field at room temperature have been measured. The X-ray and neutron diffraction data were analyzed by the rietveld refinement method. The addition of 0.1 mole DF into BF-PT system greatly increases the ferroelectric remanant polarization Pr values, e.g. 17 ${\mu}C/cm^2$ in 0.6BF-yDF-(0.4-y)PT and 31${\mu}C/cm^2$ in 0.5BF-yDF-(0.5.y)PT, respectively. The improved Pr value has been discussed in relation with crystal structure and electrical property.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.666-672
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• 1996

The optical property of CdTe thin film is important for applications such as the compound semiconductor type solar cells. CdTe films are prepared by RF sputtering at various substrate temperature between $25^{\circ}C$ and $300^{\circ}C$, then, annealed in argon gas environment at $400^{\circ}C$. The annealing process of the thin film caused variation in the film structure and the composition of films. The deformation of CdTe thin film was observed by X-ray diffractometry. After annealing, the grain size increased and the portion of the non-crystalline CdTe reduced. Futhermore, the structure of sputtered CdTe film grown at the substrate temperature more than $250^{\circ}C$ was enhanced in the (111) direction of zincblend structure. There was a discrepancy, in the spectroscopic ellipsometer spectrum, between the single crystal CdTe and the sputtered CdTe thin films, especially in the region over 3.2eV. An oxidation layer was found on the CdTe thin film by spectroscopic ellipsometry analysis.

• Textile Coloration and Finishing
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• v.15 no.5
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• pp.316-320
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• 2003

In order to investigate the dyeing property of poly trimethylene terephthalate(PTT) fabric, the dyeing of PTT fabric was carried at under condition of different dyeing temperature by using several disperse dyes with different energy level. Particularly, this study discussed the PTT dyeing thermodynamically. Used disperse dyes were selected based on the their chemical structure and energy level. The obtained results were as followings; The dye adsorption of S type disperse dye such as C. I. Disperse Blue 79 increased with increasing dyeing temperature. In a exhaustion rate of PTT fabric with disperse dyes, C. I. Disperse Blue 56 showed higher values than that of C. I. Disperse Orange 29 and Blue 79. For the interpretation of thermodynamic dyeing behavior, the partition coefficient ( K ) and some several thermodynamic parameters such as standard affinity$(-\mu^\circ)$ and heat of dyeing$(\Delta{H}^\circ)$ calculated from the adsorption isotherm. From above results, as the energy level of disperse dye is small, the partition coefficient and standard affinity increased. But the heat of dyeing of PTT fabric with disperse dye showed high negative value in order of E type(C. I. Disperse Blue 56), SE type(C. I. Disperse Orange 29) and S type(C. I. Disperse 79).

• Textile Coloration and Finishing
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• v.21 no.6
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• pp.29-38
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• 2009

Natural dyes seem to be more profitable on human and environment, and recently they could be considered as a better alternative to synthesized dyes. The aim of the current work was to investigate the dyeing property and antimicrobial activity of commercial cotton fabrics dyed with kumazasa (usually called in japan) which is known as conventional japan bamboo leaves. Actually, the dyeability and antimicrobial property of dyed fabric with natural mordant/dyeing was compared with synthetic mordant/dye process. The results of this study obtained are as follows. The apparently colour of kumazasa leaves extract dyed fabrics showed with light green or slightly yellow-green. In colorfastness to washing, ${\Delta}E$ and K/S values of dyed fabrics with natural chitosan as mordant used was shown to be more excellent results, than was synthetic mordant used. However, the decrease rate was recorded nearly 50% when washing repeated 20 cycles. In result of antimicrobial effect for bacteria, the dyed fabrics didn't show the significant antimicrobial activity to the both dyed with and without mordant. Results of this investigation considered that low-cost, natural, bio-mordant are relatively effective in natural coloration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.81-89
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• 2000

In this paper, we analyzed the performance for CATV/LAN added priority problem. Upstrea nm channel which analyzed very deeply for CATV/LAN network have the preferential access property depending upon that positionand unidirectional property. To solve that fairness problem and priority, we propose the CSMA-CD/U/P-P protocolthat transmit as P1 probability if data packets happen. We assumed 2-Class priority(high, low). As the analyticresult and simulation, we obtained P1, value and its average delay time under priority problem assumed twoscenarios. Also, we get its variance value and queue length. Especially, the mean delay time increases nearer thanposition from H/E