• Journal of electromagnetic engineering and science
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• v.16 no.3
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• pp.169-181
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• 2016

This work presents a new method for enhancing the performance of a dual band Planer Inverted-F Antenna (PIFA) and its lumped equivalent circuit formulation. The performance of a PIFA in terms of return loss, bandwidth, gain, and efficiency is improved with the addition of the proposed open stub in the radiating element of the PIFA without disturbing the operating resonance frequencies of the antenna. In specific cases, various simulated and fabricated PIFA models illustrate that the return loss, bandwidth, gain, and efficiency values of antennas with longer optimum open stub lengths can be enhanced up to 4.6 dB, 17%, 1.8 dBi, and 12.4% respectively, when compared with models that do not have open stubs. The proposed open stub is small and does not interfere with the surrounding active modules; therefore, this method is extremely attractive from a practical implementation point of view. The second presented work is a simple procedure for the development of a lumped equivalent circuit model of a dual band PIFA using the rational approximation of its frequency domain response. In this method, the PIFA's measured frequency response is approximated to a rational function using a vector fitting technique and then electrical circuit parameters are extracted from it. The measured results show good agreement with the electrical circuit results. A correlation study between circuit elements and physical open stub lengths in various antenna models is also discussed in detail; this information could be useful for the enhancement of the performance of a PIFA as well as for its systematic design. The computed radiated power obtained using the electrical model is in agreement with the radiated power results obtained through the full wave electromagnetic simulations of the antenna models. The presented approach offers the advantage of saving computation time for full wave EM simulations. In addition, the electrical circuit depicting almost perfect characteristics for return loss and radiated power can be shared with antenna users without sharing the actual antenna structure in cases involving confidentiality limitations.

• Resources Recycling
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• v.25 no.4
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• pp.60-67
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• 2016

This study was conducted to establish the adsorption-desorption mechanism and the optimum condition of chromatographic operation for separations of heavy rare earth elements (Gd, Tb, Dy) using a p507-containing resin. By employing Langmuir and Freundlich isotherm together with pseudo first and second order kinetics, absorption-desorption reaction mechanism was investigated. Langmuir and Freundlich isotherm was applied under assumption that adsorption reaction occurs in form of monolayer, and because the result was identical to the assumption, now we know adsorption of heavy rare earth elements occurs in form of monolayer. Concerning the pseudo first and second order kinetic, the pseudo second order seemed to be more suitable to represent heavy rare earth element adsorption mechanism. By using the extraction chromatography to separate heavy rare earth elements, ${\alpha}^{Tb}_{Gd}=1.24$, and ${\alpha}^{Dy}_{Tb}=1.03$ were confirmed in eluent HCl 0.25 M which indicates almost perfect separations of three elements. Furthermore, as concentrations of eluent became higher, the resolution value decreased and the elution area got shortened.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.117-124
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• 2015

Recently an opportunistic incremental relaying (OIR) system has been studied for improving the performance degradation in fading channel. However there are few studies on power control in the system, and the studies are assumed perfect knowledge of the all channels at transmitters. The assumption that the source know all channel information is difficult in practical channels. Therefore, in this paper we assume that the source knows partial channel information and propose a modified truncated channel inversion (TCI) power control scheme for the OIR system. We derive the channel capacity of the proposed system and perform Monte Carlo simulation. It is noticed that the proposed OIR system has better capacity than that of the power controlled system with direct path only, and the capacity increases with the number of relays. The power controlled OIR system gained more capacity of 29.7%, 32.7%, and 33.5% than that of the system with direct path only for the number of relays of 1, 3, and 5, respectively. The results from this paper can be applied to the estimation of a theoretical capacity for the currently operating cellular systems when they adopt the IOR system.

• KDI Journal of Economic Policy
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• v.12 no.3
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• pp.125-151
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• 1990

This paper reviews the economic liberalization experiences of the Southern Cone countries and draws some lessons from their experiences. The Southern Cone countries-Chile, Argentina and Uruguay-followed the different sequences in liberalization. Chile implemented the fiscal reform and the following comprehensive trade reform in the beginning of liberalization, but capital controls were maintained until 1979. Argentina and Uruguay placed more emphasis on the financial reform with the goods market reformed afterwards, but the fiscal sector was never reformed in Argentina. Since the serious inflation plagued the Southern Cone countries, they combined the economic liberalization scheme with the economic stabilization programmes which are based on the monetarist model. Although economic situations in the Southern Cone countries are quite different from those of Korea, we can learn many lessons from their experiences. First, the monetary and fiscal policies should consist of strict financial discipline to bring in the stable domestic inflation. Without the domestic stabilization, the financial liberalization could disturb the domestic economy as the capital inflows in particular generate a real exchange rate appreciation. Second, the monetary approach which is based on the full purchasing power parity and perfect capital mobility make stabilization as simple as a matter of the appropriate exchange rate policy and the proper rate of domestic credit creation. The unsuccessful experiences with monetarist stabilization in the Southern Cone countries suggest that the monetarist model cannot make real exchange rate and real interest rate stable with the trade and financial reform. Third, both the theory and practice have not yet provided a precise solution on the optimal sequencing and speed of the goods and financial market. Nonetheless, it seems desirable to keep the real exchange rate and the real interest rate stable by gradually opening up the current account and then the capital account.

• Journal of Korean Library and Information Science Society
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• v.50 no.4
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• pp.203-221
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• 2019

How has the use of academic journals changed since the academic library purchase policy changed from selective journals based on core journals to package purchases by big deal? The purpose of this study is to analyze the effect of supply and size of academic journals in university libraries on the use of journals. For this purpose, this study used the actual usage statistics of e-journals of K Academic Libraries during 2013-2015. The analysis shows that there is a so-called long-tail shape in which demand shifts to niche products that are effective in online platforms. Analysis of the use of academic journals by year for three years showed that the use of electronic journals in K Academic Libraries appeared to be a perfect Pareto shape, which is concentrated in the top 20% of journals. In particular, in 2015, the top 5% of journals accounted for nearly 80% of the total usage. Despite the changes in the supply method and size of academic journals, users' use of journals was still concentrated in core journals.

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.816-821
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• 1997

The hydrodynamics and the liquid flow characteristics were investigated in an internal circulation airlift reactor with a single nozzle as a gas distributor. In an air-water system, the gas holdup in the individual flow zone and the impulse-response curve of tracer were measured at various gas velocities and reactor heights. Experimental results showed that for the higher gas velocity(>about 8 cm/s), the flow behavior of bubbles in the riser was turbulent flow due to strong bubble coalescences and the axial height of dispersion zone of large bubbles having uniform sizes in the downcomer was decreased with increasing gas velocity. And mean gas holdups in the individual flow zone and the reactor were increased with increasing gas velocities and were decreased with increasing heights of the top section of the reactor and it was decreased with increasing the height of the top section and gas velocity. Flow characteristics of liquid in the riser and the downcomer was tend to access to plug flow and the overall flow behavior of liquid was mainly varied with the size of the top section which it was assumed to be perfect mixing zone. In these conditions, liquid circulation velocities were increased with increasing gas velocities and they were higher than those by using other gas distributors.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.40-47
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• 2016

Instead of metal connector generally used on the structural glued laminated timber rahmen joints, the GFRP reinforced laminated plates combining veneer and GFRP (Glass Fiber Reinforced Plastic) and bonded type GFRP rod were used as the connectors. As a result of moment resistance performance evaluation on the joint part applied with these connectors, the yield moment of specimen using the GFRP reinforced laminated plates and GFRP rod pin was measured 4 % lower in comparison to the specimen (Type-1) using the metal connectors, but the initial rotational stiffness was measured 29% higher. Also, the yield moment and rotational stiffness of the specimen using the GFRP-reinforced laminated plates and wood (Eucalyptus marginata) pin showed were measured 11% and 56% higher in comparison to the Type-1 specimen, showing the best performance. It was also confirmed through the failure shape and perfect elasto-plasticity analysis that it showed ductility behavior, not brittle fracture, from the shear resisting force by the pin and the bonding strength increased and the unification of member was carried out. On the other hand, in case of the specimen bonded with GFRP rod, it was impossible to measure the bonding performance or it was measured very low due to poor bonding.

• Restorative Dentistry and Endodontics
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• v.27 no.4
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• pp.382-388
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• 2002

Compomer is composed of matrix and filler : matrix is made of the combination of resins and polycarboxylic molecules that are light-cured, and a filler is a glass component which is capable of ion-release. The resin content of compomers produces polymerization shrinkage which can adversely affect marginal adaptation. Pretreatment is a fundamental step which is treated with conditioner or primer in the use of these materials. Microleakage of restorative materials has been investigated mostly by dye penetration method. Dye penetration method was not quantitative and not measured repeatedly. Fluid filtration method, introduced and developed by Pashley's group, has been extensively used for 20 years for research purpose to understand the physiology of dentin, as well as the effects of various restorative treatments on dentin permeability. It permits quantitative, nondestructive measurment of microleakage in a longitudinal manner. The purpose of this study was to evaluate the change of dentin permeability according to the process of compomer restoration. In this study. Cl V cavities were prepared on buccal surface of thirty extracted human molars. The prepared cavities were etched by 37% phosphoric acid. The experimental teeth were randomly divided into three groups. Each group was treated with following materials Group 1 : Prime & Bond NT/Dyract AP, Group2： Single Bond/F2000 compomer, Group 3 : Syntac Single Component/Compoglass. The bonding agent and compomer were applied for each group following manufacturers information. Dentin permeability of each group was measured at each process by fluid filtration method; Step 1 : preparation(smear layer). Step 2 : etching(smear layer removal), Step 3 : applying the bonding agent, Step 4 : filling the compomer. Dentin permeability was expressed by hydraulic conductance ($\mu\textrm{l}$ min$^{-1}$cm$H_2O$$^{-1}$). The data were analysed statistically using One-way ANOVA and Sheffe's method. The results were as follows : 1. Dentin permeability differences between each process were significant except between step 1 and step 2(p<0.01). 2. Dentin permeability after removal of smear layer was highly increased(p<0.01). 3. In most case, decrease of dentin permeability was obtained by applying bonding agent(p<0.01). 4. Dentin permeability differences among the experimental groups were not significant(p>0.05). 5. None of compomers used in this study showed perfect seal at the interface.

• Journal of Science of Art and Design
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• v.6
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• pp.140-202
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• 2004

Body means 1)the whole structure and substance of a man, animal, or plant 2) the trunk or torso of a man or animal 3) part of garment that covers the trunk 4) the fresh or material substance, as opposed to the spirit. Human body could be distinguished as fresh and spirit. Body has the meaning of physicality. Physical means the bodily and constitution, but in the meaning of constitution there is the content of spirituality. Physicality means the appearing or arising of trace or image or nuance of body. The paintings which are using bodies are 1) directly draw bodies 2) twisting or transformation or nuance of the body and highly upgrade the physical emotion or fantastic bodily nuance 3) directly rubbing artist's body on the surface of painting with pigments to elect tactile specification. These physical art have appeared broadly by various artists, mainly with the social aspects of sex, drug, psycho sexual issues. In case of Joel peter Whitkin, the reason of strong physicality in the art is from the mind of the rejection and resistance of real world which is targeting top, perfect and beauty. Further explanation, being the world which is separated top and under, men and women, beauty and ugly; further in the situation, the hierarchy, terror and pressure began and many difficult problems has derived. The contents of attacking feminists's art works are very obscene to reveal female and male's phallus strongly. Sometime, it is strongly related in the political issues. The physical paintings have strong meanings in the action by hands and feet. It supports that it could reveal the humanity with smell, breath, and traces of bodies. In the bodies, the origin of life begins which gives human life by blood lines and water. Sometime, the physical paintings are made by the blood and urine to stick the physicality for special nuance. The physical paintings are made by the image of penis and clitoris which are related in the image of urinating, ejaculation and sometime is symbolized as pens and candles to drop liquid. The selected painters who are related in physical painting are Jackson Pollock, Andrea Serano, Eve Klein, Francis Bacon, Francesco Clemente, Lichard Long, Jakes & Dinos Chapman, Anselm Kiefer, Kiki Smith and Park, Ki Woong. Francis Bacon's style is destructive in representing human shapes which give us special message about the unbearable activity of men politician, high brain, wealthy and religious people. Francesco Clemente's method is to use throat, ear hole, mouse, clitoris, belly nostrils and every holes of body to transmute human physical body. Lichard Long uses directly his body in drawing the surface of painting by using liquid of mud Jakes & Dinos Chapman destroys or transforms the bodies of human. It sometime appears wrong location of the bodies that the penis and vulva is in between human faces or nose of women, Anselm Kiefer uses human hair for representing the human decaying martyrs, and indirectly using straw, he gives special ritual action to repent the Nazi's fault. From 2002 to 2003, Park KI Woong used women womb images to intermingle the smoke shape of <9.11 terror, 2001> in New York to reveal the painful situation of the time(*).

• The Plant Pathology Journal
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• v.25 no.3
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• pp.286-290
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• 2009

The stability of three different kinds of pUC-derived plasmids, pDsRed, pZsYellow, and pGFPuv, was investigated in Pectobacterium strains to utilize those plasmids as tracers. All three plasmids pDsRed, pZsYellow and pGFPuv showed their specific colors in Pectobacterium strains. Especially, the plasmid pDsRed conferred bright pink colonies on the Pectobacterium strains. When the bacteria lost the plasmid pDsRed, the colonies turned white, suggesting that the plasmid could be a good marker system for Pectobacterium strains on different environmental conditions. The effect of the antibiotic pressure on the stability of the plasmid was different depending on the host bacteria. P. carotovorum subsp. betavasculorum was more sensitive to the antibiotic pressure than P. carotovorum subsp. carotovorum Pcc21. However, temperature change significantly affected plasmid stability on both Pectobacterium strains. Almost all strains lost the plasmids with the shift in temperature from $28^{\circ}C$ to $37^{\circ}C$. Presence of the plasmids did not affect bacterial pathogenicity on their own host plants. Among three plasmids, pZsYellow was not useful as a marker because the yellow fluorescent proteins from pZs Yellow were interfered with the yellow natural fluorescence of the plant tissues induced by the defense system. Since the red color of DsRed can be seen with naked eyes, plasmid pDsRed was applicable as a marker. However, the color change was slow so that additional manipulation to increase the expression speed was necessary. Plasmid pGFPuv could serve as a perfect marker without any problem, tracing the reproduction and spread of the plant pathogens perfectly.