• Journal of Korean Society for Geospatial Information Science
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• v.19 no.3
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• pp.13-21
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• 2011

In mobile environment supporting mobility technologies, user requirements have been increased with respect to utilization of location information. In particular, moving object DBMS has consistently posed in order to efficiently maintain traffic information related to location of vehicle which tents to tremendously change over time. Despite the fact that these sorts of researches must be taken into consideration, empirical studies on moving object in terms of map database for lbs service, spatial attribute of which is continuously changed over time, have rarely performed. Therefore, aim of this paper is to suggest efficient spatial index scheme, which is capable of supporting query processing algorithm and location of moving object over time, by developing new empirical model. As a result, we can come to the conclusion that moving object model based on multi-fixed grid index makes it possible to cut down on the number of entity for retrieving. What's more, this model enables hierarchical data to be accessed through efficient spatial filtering on large-scale lbs data and constraints in accordance with level in order to display map.

• Journal of Korea Spatial Information System Society
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• v.11 no.4
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• pp.47-55
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• 2009

As the wireless internet technology such as mobile phone, WIBRO, HSDPA develops, customized location-based services for traffic, tourism, shopping, and emergency relief has lately attracted attention. For giving customized services. we should consider dynamic characteristics of moving object which continuously change their location. In this paper, we define the context trigger type of moving object and design triggering method for processing context generated by moving object. Also we propose location-based push service platform including context trigger of moving object for supporting location-based information to user. The proposed system gathers moving object stream from the terminal based on MS-assisted or Stand-alone positioning mode of embedded GPS in terminal extract user context by user device agent, and send context information to server.

• Journal of the Korean Geotechnical Society
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• v.34 no.7
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• pp.29-38
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• 2018

Three-dimensional continuum modeling of dynamic soil-pile-structure interaction embedded in a liquefiable sand was carried out. Finn model which can model liquefaction behavior using effective stress method was adopted to simulate development of pore water pressure according to shear deformation of soil directly in real time. Finn model was incorporated into Non-linear elastic, Mohr-Coulomb plastic model. Calibration of proposed modeling method was performed by comparing the results with those of the centrifuge tests performed by Wilson (1998). Excess pore pressure ratio, pile bending moment, pile head displacement-time history according to depth calculated by numerical analysis agreed reasonably well with the test results. Validation of the proposed modeling method was later performed using another test case, and good agreement between the computed and measured values was observed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1054-1060
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• 2002

In this paper, a new parallel-coupled-line microstrip BPF(BandPass Filter) improving the suppression performance of 2nd harmonic signals is studied. Using the consecutive pattern in coupled-line, the desired passband performance is improved and harmonic passband signal is rejected. Recalculation of classical filter design parameters(space-gap between lines, line widths and lengths) is not required. That is, after using the classical design methodology for parellel-coupled-line BPF, new filters can be easily realized by inserting periodic patterns in coupled-line. To investigate the validity of this novel technique, order-3 Butterworth BPF centered at 2.5 GHz with a 10 % FBW(Fractional Bandwidth) and order-5 Chebyshev BPF centered at 10 GHz with a 15 % FBW were used. When five and three square grooves are used, over 30 dB harmonic suppression at 2nd harmonic is achieved in simulation and experiment.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.581-587
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• 1988

The solvolysis of substituted benzyl bromides was studied in binary solvent mixtures of acetone-water and ethanol-water at $25^{\circ}C$ and $45^{\circ}C$. The rate constants increase with electron-donating substituents in benzene ring and increasing of water contents in both of solvent mixtures. The sensitivity parameter (m) of the solvolysis of substituted benzyl bromides to solvent ionizing power (Y) was decreased in going from the electron-donating group to electron-withdrawing one, whereas their nucleophilic sensitivity increased continuously in going to above same substituents. It was shown that electron-donating (electron-withdrawing) groups make the transition state looser (tighter). The above results were consisted with the account for the potential energy surface model and the quantum mechanical approach.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.2
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• pp.83-100
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• 1980

This study was intended to computerize the structural analysis of two-dimensional continuum by finite element method, and to provide a preparatory basis for more sophisticated and more generalized computer programs of this kind. A computer program, applicable to any shape of two-dimensional continuum, was formulated on the basis of 16-degree-of- freedom rectangular element. Various computational aspects pertaining to the implementation of finite element method were reviewed and settled in the course of programming. The validity of the program was checked through several case studies. To assess the accuracy and the convergence characteristics of the method, the results computed by the program were compared with solutions by other methods, namely the analytical Navier's method and the framework method. Through actual programming and analysis of the computed results, the following facts were recognized; 1) The stiffness matrix should necessarily be assembled in a condensed form in order to make it possible to discretize the continuum into practically adequate number of elements without using back-up storage. 2) For minimization of solution time, in-core solution of the equilibrium equation is essential. LDLT decomposition is recommended for stiffness matrices condensed by the compacted column storage scheme. 3) As for rectangular plates, the finite element method shows better performances both in the accuracy and in the rate of convergence than the framework method. As the number of elements increases, the error of the finite element method approaches around 1%. 4) Regardless of the structural shape, there is a uniform tendency in convergence characteristics dependent on the shape of element. Square elements show the best performance. 5) The accuracy of computation is independent of the interpolation function selected.

• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.401-409
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• 2007

A new sheet of back light unit(BLU) to reduce the number of sheets and enhance the optical performances of direct back light unit(BLU) in a liquid crystal display is proposed and designed. In order to improve the straightness and spatial uniformity of brightness of the BLU, we design the new sheet with linear arrays of complicated bar prism by using the fusion of cylindrical lens and bar prism. Then, we investigate and analyze various optical performances of a BLU including the new sheet through an illumination optical system design program. From these results, we determine the optimum geometrical structure of the sheet. Under the optimum condition, the luminance efficiency and spatial uniformity of luminance of the BLU are 53.5% and 83.5% respectively. And the vertical and horizontal widths of the angular luminance distribution are $90^{\circ}$ and $112.5^{\circ}$ respectively. Finally we have fabricated a new BLU sheet according to this design shape by using an ordinary resins.

• Korean Journal of Crystallography
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• v.4 no.2
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• pp.100-104
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• 1993

Reduced glutathione (GSH) plays a vital role in the metabolism of all cells. Glutathions, a tripeptide cowfosed of glutamic acid, cysteane, and gtycina is synthesized by two synthesized reutions. The first is catalyzed by Y-glutamylcysteine synthetase (GSH-I) and the second by glutathione synthetase (GSH-ll). The glutathione biosynthetic pathway of E. coziis mainly controlled by nonallosteric feedback inhibition of GHS-I by GSH. Determination of the three-dimensional structure of GSH-I by X-ray crystallography is necessary in order to understand the structure-function relationship at the molecular level. As the (irst step toward its structure determination, crystallization of 5. coli V-glutamylcystfine synthetase (GSH-I) has been achived using the hanging drop vapor diffusion method and capillaw method. Crystals of GSH-I have been grown from ammonium sulfate solution. The crystals grew at room temperature within 10 days to dimensions of 0.2 m x 0.2 m x 0.2 ml by hanging drop vapor diffusion method and diffracted to about 4 A resolution using synchrotron X-rays. Another crystal, grown by the capillary method to dimensions of 0.25 mm x 0.25 mm x 0.3 mm within 40 days, diffracted to about 4 A resolution using X-rays from a rotating anode.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.273-273
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• 2011

현재 사용되고 있는 플로팅 게이트를 이용한 플래시 메모리 소자는 비례축소에 의해 발생하는 단 채널 효과, 펀치스루 효과 및 소자간 커플링 현상과 같은 문제로 소자의 크기를 줄이는데 한계가 있다. 이러한 문제를 해결하기 위하여 silicon nitride와 같은 절연체를 전자의 트랩층으로 사용하는 charge trap flash (CTF) 메모리 소자에 대한 연구가 활발히 진행되고 있다. CTF 메모리 소자의 전기적 특성에 대한 연구는 활발히 진행 되었지만, 수치 해석 모델을 사용하여 메모리 소자의 전하수송 메커니즘을 분석한 연구는 매우 적다. 본 연구에서는 수치 해석 모델을 적용하여 개발한 시뮬레이터를 사용하여 CTF 메모리 소자의 프로그램 동작 시 전하수송 메커니즘에 대한 연구를 하였다. 시뮬레이터에 사용된 모델은 연속방정식, 포아송 방정식과 Shockley-Read-Hall 재결합 모델을 수치해석적 방법으로 계산하였다. 또한 CTF 소자 프로그램 동작 시 트랩 층으로 주입되는 전자의 양은 Wentzel-Kramers-Brillouin 근사 법을 이용하여 계산하였다. 트랩 층에 트랩 되었던 전자의 방출 모델은 이온화 과정을 사용하였다. 게이트와 트랩 층 사이의 터널링은 Fowler-Nordheim (FN) tunneling 모델, Direct tunneling 모델, Modified FN tunneling 모델을 적용하였다. FN tunneling 만을 적용했을때 보다 세가지 모델을 적용했을 때가 더 실험치와의 오차가 적었다. 그 이유는 시뮬레이션 결과를 통해 인가된 전계에 의해 Bottom Oxide 층의 에너지 밴드 구조가 변화하여 세가지 tunneling 모델의 구역이 발생하는 것을 확인 할 수 있었다. 계산된 결과의 전류-전압 곡선을 통해 CTF 메모리 소자의 프로그램 동작 특성을 관찰하였다. 트랩 층의 전도대역과 트랩 층 내부에 분포하는 전자의 양을 시간에 따라 계산하여 트랩 밀도가 시간이 지남에 따라 일정 값에 수렴하고 많은 전하가 트랩 될 수록 전하 주입이 줄어듬을 관찰 하였다. 이와 같은 시뮬레이션 결과를 통해 CTF 메모리의 트랩층에서 전하의 이동에 대해 더 많이 이해하여 CTF 소자가 가진 문제점 해결에 도움을 줄 것이다.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.87-96
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• 2006

Selectivity estimation is one of the query optimization techniques. It is difficult for the previous selectivity estimation techniques for moving objects to apply the position change of moving objects to synopsis. Therefore, they result in much error when estimating selectivity for queries, because they are based on the extended spatial synopsis which does not consider the property of the moving objects. In order to reduce the estimation error, the existing techniques should often rebuild the synopsis. Consequently problem occurs, that is, the whole database should be read frequently. In this paper, we proposed a moving object histogram method based on quad tree to develop a selectivity estimation technique for moving object queries. We then analyzed the performance of the proposed method through the implementation and evaluation of the proposed method. Our method can be used in various location management systems such as vehicle location tracking systems, location based services, telematics services, emergency rescue service, etc in which the location information of moving objects changes over time.