• Journal of KIISE:Databases
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• v.33 no.4
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• pp.363-371
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• 2006

In spite of computer's development, the present state of a lot of electronic documents overflowed it's going to be more difficult to get appropriate information. Therefore it's more important to get meaningful information than to focus on the speed of processing. Semantic web enables and intelligent processing by adding semantic meta data on your web documents. Also as the semantic web grows, the knowledge resource is more important. In this paper, we propose a RDF storage system using relational database model aimed at intelligent processing by adding semantic meta data on your web documents, also a query processor aimed at query processing through the storage system. By using relational model, we could overcome a weakness of object or memory model.

• Journal of Integrative Natural Science
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• v.3 no.4
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• pp.226-230
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• 2010

Calculation of partial charge is important in chemistry. However, because there are many methods developed, it is of considerable interest to know how to calculate and apply properly to address various chemical problems. For basis set, usually double zeta quality is acceptable, and double zeta polarization function would be enough for most cases. To describe electronic state more accurately, Many electron configurations would be necessary to describe highly strained or anionic species. The NPA population introduced new concept about amide bonds, i.e., the planar geometry of nitrogen atom may not come from resonance, but from the lowering of p-orbital energy by electronegative carbonyl carbon atom. The issues for hypervalent atomic charges was also addressed by various charge derivation scheme. When the charge schemes were applied to organolithium compounds, the ionic nature of boding was revealed. This comes from the fact that previous Mulliken partial atomic charges overemphasized the covalent character, wihout much justification. The other partial charge derivation schemes such as NPA(natural population analysis), IPP (Integrated Projected Population) showed that much more ionic picture. ESP potential derived charges are generally believed to be suitable to describe intermolecular interactions, therefore they are used for molecular dynamics simulations and CoMFA (comparative molecular field analysis). The charge derivation schemes using multipole polarization was mainly applied to reproduce experimental infrared spectroscopy. In some reports these schemes are also suitable for intermecular electrostatic interactions. Charges derived from electron density gradient have shown the some bonds are not straight, but actually bent. The proper choice of charge-calculation method along with suitable level of theory and basis set are briefly discussed.

• Korean Business Review
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• v.11
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• pp.385-414
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• 1998

At the point of increasing concern on EDI (Electronic Data Interchange) and on related trade automation, a research of trade enterprises' EDI system adoption and using has a very significant meaning to get the roots of the problems and to put the practical use. After studying the outline of EDI and it's proceeding state, this thesis tries to point out some problems of them and presents the reform measures in the aspect of a legal and business aspect. According to the results of this study, the argues and their control suggestions are as follows. First, the process of trade relations and the it's public concept on the EDI should be changed to the agreement of the adopting and using the standard EDI in Korea. Second, the financial and tax support is needed to the following; the reconsideration of each enterprise, the inrestment of enterprises' role for the training their professional human resource and goverment and related organization's guiding role. Therefore, to maximize the effects of EDI after solving the issues. above trade process the issues should be unified by coorperation with the goverment and related organizations for the information circulation side and considered that EDI system have to positively make automation of trade on the basis of suggestions above.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.3
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• pp.72-83
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• 2000

This paper presents the implementation of the position control system for 3 phase induction motor using reaching mode controller and neural networks. The reaching mode controller is used to bring the position error and speed error trajectories toward the sliding surface and to train neural networks at the first time. The structure of the reaching mode controller consists of the switch function of sliding surface. And feedforward neural networks approximates the equivalent control input using the reference speed and reference position and actual speed and actual position measured form an encoder and, are tuned on-line. The reaching mode controller and neural networks are applied to the position control system for 3 phase induction motor and, are compared with a PI controller through computer simulation and experiment respectively. The results are illustrated that the output of reaching mode controller is decreased and feedforward neural networks take charge of the main part for the control action, and the proposed controllers show better performance than the PI controller in abrupt load variation and the precise control is possible because the steady state error can be minimized by training neural networks.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.9
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• pp.1-8
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• 1999

In this paper, we propose and analyze a concatenated coding scheme for DS/CDMA systems in asynchronous channels. In the concatenated coding, bandwidth efficient $2^{2L-2}$-state ${\frac{L}{L+1}}$-rate 2-MTCM with biorthogonal signal constellation is used for the inner code, and $(2^{L-1},\;{\lceil}\frac{2^{L-1}}{L/2}{\rceil})$ RS code is use for the outer code. It is shown that we can get considerable performance gain over the uncoded system without sacrificing the data transmission rate. The proposed system can be used as a coding scheme for reliable and high speed integrated information services of mobile communication systems.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.6
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• pp.85-94
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• 2015

In this paper, an enhanced QoS multicast routing scheduling scheme is proposed to adapt to a dynamic mobile traffic condition for wireless mesh networks (WMNs). It handles the network QoS by controlling the delay constraints for multimedia applications. The group size will be controlled according to both the current network state and QoS requirements. The dynamic reconstruction of QoS multicast tree can be obtained from preprocessing with both the partial multicast routing scheme and the traffic estimation. Performance evaluation of the proposed scheme is carried out on randomly generated graph derived from the wireless mesh network, by choosing the optimal value related to the appropriate delay bounds. Simulation results show that the proposed scheme can improve the performance of QoS multicast routing for WMNs.

• Journal of the Korean Chemical Society
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• v.46 no.2
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• pp.164-168
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• 2002

SrGa$_2$S$_4$ : Eu is a green emitting phosphor which is applied for field emission display, and cathodoluminescence. Conventionally, SrGa$_2$S$_4$ : Eu is synthesized by solid state reaction, in which a mixture of SrCO$_3$, Ga$_2$O$_3$, and Eu$_2$O$_3$ is fired at high temperatures under flowing H$_2$S and Ar gases. In this study,SrGa$_2$S$_4$ : Eu phosphor is synthesized by using a decomposition method, where SrS, Eu complex, and Ga com-plex are used. The advantage of this method is that toxic H$_2$S gas and Ar gas are not used. The synthetic con-ditions and luminescent properties of SrGa$_2$S$_4$ : Eu phosphor are also investigated.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.894-898
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• 2011

The first example of lead compound from $Pb(NO_3)_2$ and $H_3L$ N-heterocyclic ligand $(H_3L\;=\;(HO_2C)_2(C_3N_2)(C_3H_7)CH_2(C_6H_4)(C_6H_3)CO_2H)$, $[Pb_4(L')_4]{\cdot}5H_2O$ 1 (L' = OOC$(C_3H_7)(C_3N_2)CH_2(C_6H_4)(C_6H_3)COO)$, has been obtained under hydrothermal condition by decarboxylation, and characterized by elemental analysis, IR, TGDTA, and single-crystal X-ray diffraction. Compound 1 possesses a rare two-dimensional upper-lower offset terrace-like layer structure. In 1, crystallographic distinct Pb(II) ion adopts five-coordination geometry, and two lattice water molecules occupy the voids between 2-D layers. Results of solid state fluorescence measurement indicate that the emission band 458 nm may be assigned to $\pi^*-n$ and $\pi^*-\pi$ electronic transitions within the aromatic systems of the ligand L', however, the emission bands centred at 555 nm, 600 nm and 719 nm may be derived from phosphorescent emission ($\lambda_{excitation}$ = 390 nm).

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.277-280
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• 2011

We studied the relative stability and atomic structure of five $C_{20}^{2+}$ isomers obtained by two-electron ionization of a $C_{20}$ cage (the smallest fullerene). All the isomers are bond-stretch isomers, i.e., they differ in bond length. In particular, in one of the isomers with Ih symmetry, all the bond lengths are equal. Full geometry optimizations of the dipositive ion $C_{20}^{2+}$ were performed using the hybrid density functional (B3LYP/6-31G(d)) methods. All isomers were found to be true minima by frequency analysis at the level of B3LYP/6-31G(d) under the reinforced tight convergence criterion and a pruned (99,590) grid. The zero-point correction energy for the cage bond-stretch isomers was in the increasing order $D_{2h}<C_{2h}<C_2<T_h<I_h$ of $C_{20}^{2+}$. The energy difference among the isomers of cage dipositive ions was less than that among neutral cage isomers. Our results suggest that these isomers show bond-stretch isomerism and that they have an identical spin state and an identical potential energy curve. Although the predominant electronic configurations of the isomers are similar, the frontier orbital characteristics are different, implying that we could anticipate an entirely different set of characteristic chemical reactions for each type of HOMO and LUMO.

• Journal of Electrochemical Science and Technology
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• v.2 no.1
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• pp.1-7
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• 2011

Nanocomposites of reduced graphene oxide and manganese (II,III) oxide can be synthesized by the freeze-drying process of the mixed colloidal suspension of graphene oxide and manganese oxide, and the subsequent heat-treatment. The calcined reduced graphene oxide-manganese (II,III) oxide nanocomposites are X-ray amorphous, suggesting the formation of homogeneous and disordered mixture without any phase separation. The reduction of graphene oxide to reduced graphene oxide upon the heat-treatment is evidenced by Fourier-transformed infrared spectroscopy. Field emission-scanning electronic microscopy and energy dispersive spectrometry clearly demonstrate the formation of porous structure by the house-of-cards type stacking of reduced graphene oxide nanosheets and the homogeneous distribution of manganese ions in the nanocomposites. According to Mn K-edge X-ray absorption spectroscopy, manganese ions in the calcined nanocomposites are stabilized in octahedral symmetry with mixed Mn oxidation state of Mn(II)/Mn(III). The present reduced graphene oxide-manganese oxide nanocomposites show characteristic pseudocapacitance behavior superior to the pristine manganese oxide, suggesting their applicability as electrode material for supercapacitors.