• Journal of Pharmaceutical Investigation
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• v.25 no.4
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• pp.323-330
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• 1995

Ceftezole pivaloyloxymethyl ester(CFZ-PV) was synthesized to improve oral absorption and bioavailability of parent drug by esterification of ceftezole(CFZ) with chloromethyl pivalate. The successful synthesis of CFZ-PV was conformed by spectroscopic analysis. Partition coefficient studies showed that CFZ-PV is more lipophillic than CFZ. The pharmacokinetic characteristics of CFZ-PV and CFZ were compared following oral administrations of these compounds to rabbits. The amount of CFZ in plasma was determined with an HPLC method. The ester compound (prodrug) was not detected in plasma following oral administration of CFZ-PV, and although CFZ-PV had not microbiological activity in vitro, the plasma taken after oral administration of CFZ-PV had microbiological activity. From above observations, it was noted that CFZ-PV is rapidly hydrolyzed to CFZ in the body. And the oral absorption of CFZ-PV was increased by yielding 2-fold bioavailability rather than CFZ. Therefore, CFZ-PV could be a novel prodrug of CFZ which can improve the oral bioavailability of CFZ.

• Journal of the Korean Chemical Society
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• v.17 no.6
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• pp.406-410
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• 1973

Kinetic study of halide exchange for dimethylsulfamoyl chloride in dry acetone by using radioisotopic halide ions has been carried out at two temperatures. The result of the order of nucleophilicity, as compared with benzenesulfonyl chloride, shows a similar tendency but reaction rate is slower, more than $10^{-2}$times, than benzenesulfonyl chloride. The activation parameter, ${\Delta}H^{\neq}\;and\;{\Delta}S^{\neq}$ decrease in sequence $Cl^-\;>\;Br^-\;>\;I^-$ in dimethylsulfamoyl chloride but it is the reverse order found for benzenesulfonyl chloride. The results are interpreted with bond-breaking, bond-formation, and electronic requirments, and in the light of HSAB Principle.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.229-232
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• 2008

Researches on the steel-concrete composite girder filled with plain concrete have been being actively performed on the grounds that this type of girder has constructional, structural and aesthetical benefits. As a part of studies on the characteristics of inner shear connections in the concrete-filled steel-concrete composite girder with plain concrete, the confinement effect on the stiffness of inner shear connections was examined in this study. In the case of concrete-filled steel-concrete composite girder, it can be expected that the stiffness of shear connections may be increased in comparison with the case not confined. Therefore, the experimental studies were performed with the confinement effect as a parameter, and the results are discussed in this paper.

• Computational Structural Engineering
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• v.10 no.4
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• pp.267-280
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• 1997

This paper deals with the development of simplified methods to predict the creep deformation of reinforced concrete beams. The layer approach based on a degenerate kernel of compliance function in form of Dirichlet series is mentioned and a simplified analytical method derived from the equilibrium equations and compatibility conditions is proposed to overcome the sophisticated calculation procedures in the classical creep analysis. Correlation studies between analytical and experimental results and design codes are conducted with the objective to establish the validity of the proposed methods. Besides, various parameter studies are conducted with the objective to identify the effects of cracking, steel ratio and sectional shape in the creep deformation and the obtained results are discussed.

• Steel and Composite Structures
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• v.23 no.6
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• pp.657-668
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• 2017

In the most of previous studies, researchers have restricted their own studies to consider the effect of single walled carbon nanotubes as a reinforcement on the vibrational behavior of structures. In the present work, free vibration characteristics of functionally graded annular plates reinforced by multi-walled carbon nanotubes resting on Pasternak foundation are presented. The response of the elastic medium is formulated by the Winkler/Pasternak model. Modified Halpin-Tsai equation was used to evaluate the Young's modulus of the multi-walled carbon nanotube/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. The exponential shape factor modifies the Halpin-Tsai equation from expressing a straight line to a nonlinear one in the multi-walled carbon nanotubes wt% range considered. The 2-D generalized differential quadrature method as an efficient and accurate numerical tool is used to discretize the equations of motion and to implement the various boundary conditions. The effects of two-parameter elastic foundation modulus, geometrical and material parameters together with the boundary conditions on the frequency parameters of the plates are investigated. This study serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analysis of annular plates.

• Korean Journal of Plant Taxonomy
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• v.49 no.4
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• pp.334-344
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• 2019

The genome size is defined as the amount of DNA in an unreplicated gametic chromosome complement and is expressed as the 1C value. It is a fundamental parameter of organisms that is useful for studies of the genome, as well as biodiversity and conservation. The genome sizes of Korean plants, including Carex (Cyperaceae), have been poorly reported. In this study, we report the genome sizes of 43 species and infraspecific taxa of Korean Carex using flow cytometry, and these results represent about 24.4% of the Carex species and infraspecific taxa distributed on the Korean peninsula. The Plant DNA C-Value Database (release 7.1) updated with and now including our data (a total of 372 Carex accessions) shows that the average genome size of members of the Carex species is 0.47 pg (1C), and the largest genome (C. cuspidate Bertol.; 1C = 1.64 pg) is 8.2 times larger than the smallest (C. brownii Tuck., C. kobomugi Ohwi, C. nubigena D. Don ex Tilloch & Taylor, and C. paxii Kuk.; 1C = 0.20 pg). The large genomes are frequently found in the subgen. Carex, especially in sect. Aulocystis, sect. Digitatae, sect. Glaucae, sect. Paniceae, and sect. Siderostictae. Our data updates the current understanding of genome sizes in Carex. This will serve as the basis for understanding the phylogeny and evolution of Carex and will be especially useful for future genome studies.

• Korean Journal of Child Studies
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• v.36 no.5
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• pp.1-18
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• 2015

The purpose of this study is to understand how the factors related to quality in child care services effect decision making of parents to use such services again, using the parameter of parental satisfaction as a measure. In order to support the researcher's hypothesis, data was gathered from 566 households who send their children to one of the child care facilities in Goyang-Shi, Gyeonggi-Do. The collected data was then analyzed by means of structural equation modeling. The results of the analysis showed that the higher the level of assurance, service tangibility and empathy were, the more the parents were satisfied with the service. The more they were satisfied, the possibility of using the service again increased relatively. In conclusion, various political and practical implications were also addressed and discussed on the basis of these results, with the aim to improve the factors of quality in child care services and parental satisfaction.

• Steel and Composite Structures
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• v.18 no.3
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• pp.547-563
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• 2015

Deflection in a beam of a composite frame is a serviceability design criterion. This paper presents a methodology for rapid prediction of long-term mid-span deflections of beams in composite frames subjected to service load. Neural networks have been developed to predict the inelastic mid-span deflections in beams of frames (typically for 20 years, considering cracking, and time effects, i.e., creep and shrinkage in concrete) from the elastic moments and elastic mid-span deflections (neglecting cracking, and time effects). These models can be used for frames with any number of bays and stories. The training, validating, and testing data sets for the neural networks are generated using a hybrid analytical-numerical procedure of analysis. Multilayered feed-forward networks have been developed using sigmoid function as an activation function and the back propagation-learning algorithm for training. The proposed neural networks are validated for an example frame of different number of spans and stories and the errors are shown to be small. Sensitivity studies are carried out using the developed neural networks. These studies show the influence of variations of input parameters on the output parameter. The neural networks can be used in every day design as they enable rapid prediction of inelastic mid-span deflections with reasonable accuracy for practical purposes and require computational effort which is a fraction of that required for the available methods.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.1
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• pp.20-27
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• 2001

In this paper, we propose a method for estimating the peak load of pole-transformer in summer season considering the degree of cooling load possession in customer. The cooling load of customer is selected as the most reliable parameter of peak load in summer season. The proposed estimation method is restricted to the aspect of load management for pole-transformer. The main concept of proposed method is that the error of peak load estimation using load regression equation reduces with considering the degree of cooling load possession in customer. We propose an index for estimation of cooling load possession in each customer. The proposed index is defined as cooling load possession in customer (CLPC) and obtained from the increment of monthly electric energy. The membership function for deciding the uncertainty of cooling load possession in customer is used. The database of pole-transformer in Korea Electric Power Corporation (KEPCO) is used for case studies. Through the case studies, we verify that the proposed method reduces the error of peak load estimation than the conventional method in domestic.

• Journal of Power Electronics
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• v.12 no.5
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• pp.787-799
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• 2012

Real and reactive power flows on a transmission line interact inherently. This situation degrades power flow controller performance when independent real and reactive power flow regulation is required. In this study, a quasi multi-pulse interline power flow controller (IPFC), consisting of eight six-pulse voltage source converters (VSC) switched at the fundamental frequency is proposed to control real and reactive power flows dynamically on a transmission line in response to a sequence of set-point changes formed by unit-step reference values. It is shown that the proposed hybrid fuzzy-PI commanded IPFC shows better decoupling performance than the parameter optimized PI controllers with analytically calculated feed-forward gains for decoupling. Comparative simulation studies are carried out on a 4-machine 4-bus test power system through a number of case studies. While only the fuzzy inference of the proposed control scheme has been modeled in MATLAB, the power system, converter power circuit, control and calculation blocks have been simulated in PSCAD/EMTDC by interfacing these two packages on-line.