• Journal of KIISE:Databases
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• v.31 no.6
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• pp.641-649
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• 2004

The relationship between chemical structures and biological activities is researched briskly in the area of 'Medicinal Chemistry' At the base of these structure-based drug design tries, medicinal chemists search the existing drugs of similar chemical structure to target drug for the development of a new drug. Therefore, it is such necessary that an automatic system selects drug files that have a set of chemical moieties matching a user-defined query moiety. Substructure searching is the process of identifying a set of chemical moieties that match a specific query moiety. Testing for substructure searching was developed in the late 1950s. In graph theoretical terms, this problem corresponds to determining which graphs in a set are subgraph isomorphic to a specified query moiety. Testing for subgraph isomorphism has been proved, in the general case, to be an NP- complete problem. For the purpose of overcoming this difficulty, there were computational approaches. On the 1990s, a US patent has been granted on an atom-centered indexing scheme, used by the RS3 system; this has the virtue that the indexes generated can be searched by direct text comparison. This system is commercially used(http://www.acelrys.com/rs3). We define the RS3 system's drawback and present a new indexing scheme. The RS3 system treats substructure searching with substring matching by means of expressing chemical structure aspredefined strings. However, it has insufficient 'rerall' and 'precision‘ because it is impossible to index structures uniquely for same atom and same bond. To resolve this problem, we make the minimum-cost- spanning tree for one centered atom and describe a structure with paths per levels. Expressing 2D chemical structure into 1D a string has limit. Therefore, we break 2D chemical structure into 1D structure fragments. We present in this paper a new index technique to improve recall and precision surprisingly.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.2
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• pp.127-138
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• 1996

The strip method, unified theory and 3-D panel method are commonly used methods for the seakeeping analysis of high-speed vessels. The strip method which is basically 2-dimensional method is known to give incorrect hydrodynamic coefficients and motion responses for the cases of high speed and low frequency region. And the unified theory which uses two dimensional approach in inner domain and slender body theory in outer domain is very complicate in computational modelling. Though the 3-D panel method requires comparatively long computation time, it is believed that the method gives good results without any limitation in ship speed and range of frequency for computation. In the 3-D panel method the source singularity representing translating and pulsating Green function is used and Hoff's method is adopted for the numerical calculation of the Green function. The computation time can be reduced by using the symmetry relationship with respect to longitudinal axis. In this paper the strip method and the 3-D panel method are compared for the seakeeping analysis of a high-speed catamaran. The Compared items are the hydrodynamic coefficients, wave exciting forces, frequency response functions and short-term responses in irregular waves.

• Journal of the Korea Convergence Society
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• v.2 no.3
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• pp.15-23
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• 2011

This paper deals with the analysis for the operation characteristic of PV 3 phase inverter, considering the state equation through d-q coordinates transformation, and proposes an algorithm of controlling current using PI(Proportional Integral) controller to control the output and the theory algorithm of sinusoidal PWM method to design inverter. And also this paper performs PV modelling using PSCAD/EMTDC S/W which is commonly used in analysis of distribution system and confirms effectiveness of the modelling proposed in this paper by analyzing and comparing the EMTDC/PSCAD simulation result with the theoretical method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.408-416
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• 2010

A study on the calibration of an X-band HPS(Hongik Polarimetric Scatterometer) system for ground-based operation is presented in this paper. In order to calibrate the scatterometer system, the degree of its distortions are analyzed by comparison between theoretical- and measured-values using the theoretically well-known calibration targets such as a metal sphere, a trihedral corner reflector(CR) and a metal cylinder. The calibration works in the field conditions depend on the precise and stable measurements of those calibration target. we present a measurement technique, so-called, an automatic 2-D target-scanning technique, using the incidence-angle(${\xi}-$ and ${\phi}-$ directions) control of HPS system. Then, we used STCT(Single-Target Calibration Technique) and GCT(General Calibration Technique) to calibrate a distortion of the scatterometer system, and measured the polarimetric RCS(Radar Cross Section) and phase-difference of a trihedral-CR as a test-target to verify the accuracy of the calibration technique. Then, three different types(i.e., 10, 20, 30 cm) of trihedral-CR were used. we obtained the error ranges about ${\pm}1.0$dB, ${\pm}0.5$ dB in a polarimetric RCS and about $-20^{\circ}{\sim}0^{\circ}$ and ${\pm}5^{\circ}$ in the co-polarized phase-difference by using the GCT and STCT, respectively.

• Journal of Korea Technology Innovation Society
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• v.20 no.1
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• pp.239-270
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• 2017

This paper examines the relationship between ownership structure and the intensity of R&D expenditures of a firm by analyzing the panel data composed of 553 manufacturing firms in KSE(Korea Stock Exchange) and KOSDAQ listed firms for the period of 2007-2014. The major findings are as follows; (1) Regarding the relationship between CEO stockholding and R&D intensity, we find the inverted-U shape relationship in KOSDAQ firms, consistent with the theoretical discussion and empirical studies on U.S. firms. The result suggests that management stockholding reduces agency problem at the R&D margin. On the contrary, the insignificant result in KSE firms seems to be due to the scant stockholding of most 'non-owner' CEOs. (2) Regarding the relationship between the largest shareholder's portion and R&D intensity, KSE firms exhibit negatively significant relationship, suggesting the existence of serious agency problem between the largest shareholder and the minor shareholders. This agency problem seems to be alleviated in KOSDAQ firms mainly because the founders with technology expertise are still in charge of the business. (3) Foreign investors seem to fail in effectively encouraging R&D expenditures in either KSE or KOSDAQ listed firms. This study contributes to the existing literature by showing for the first time that ownership structure affects R&D activities in different ways between KSE and KOSDAQ firms.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.779-786
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• 1986

Hot-wire anemometer with constant temperature hot-wire anemometer bridge, linearizer, D.C. stabilization electric power source and square-wave generater has been constructed for trial and the test has been carried out. As a result the test showed the overall frequency response of 6KHz over the change of air flow and the noise of approximately 1cm/s in an air flow of 10m/s. The accuracy of the lienarizer stands comparison with the existing anemometer and turned out to be relatively good operational characteristics.

• The Journal of the Acoustical Society of Korea
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• v.7 no.2
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• pp.65-73
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• 1988

In this paper, V(z) curve has been analyzed theoretically and compared with the experimental result, and the relation between the V(z) curve and the material characteristic has been studied. Angular spectrum and ray optics theory have been used for theoretical analysis and the acoustic microscope operating at a center frequency of 3 MHz has been used for experiment. In experiment, it has been shown that each material has a V(z) curve of a unique form and the interval of dips appearing in the V(z) curves have been used to determine the Rayleigh wave velocity.

• ETRI Journal
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• v.9 no.2
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• pp.96-105
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• 1987

The purpose of this paper is to report the implementation of new frame synchroniazation circuit for D3/PCM.When the D3/PCM signal(1.544Mb/s) is received, the performance of the new frame synchronizer is evaluated by the statistical method according to the parameters BER,es, em. For BER=$10^-2$, es=0 and em=2, the implemented hardware will render the initial search time, the maintenance time and there frame time equals to 2.87ms, 9.9hrs and2.69ms, respectively. Also the proposed frame synchronizer can be easily modified to the practical transmission channels environment and the new 1.544Mb/s signal format.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.37-45
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• 2009

The experimental study was carried out to evaluate the characteristics of the point load index and the uniaxial compressive strength of inherently anisotropic shale in the laboratory. In the testing program the effects of size and the shape on the point load index were investigated both in the axial and diametral direction. In general, the point load index of the shale was constant when the length/diameter (L/D) ratio of the specimen is greater than 1.0 in the diametral direction. The point load index in axial direction shows slight decrease as the L/D ratio is increased and the corner breakage was observed when L/D ratio is greater than unity. The minimum point load index was observed in the bedding angle of $\beta=15^{\circ}{\sim}30^{\circ}$ in the axial point load tests and of $\beta=30^{\circ}$ in the uniaxial compression tests. The relationship between the point load index and the uniaxial compressive strength was linear to ${\sigma}_c=25.0 I_{s(50)}$ for the specimen with the bedding plane angle, $\beta$ at the range of $0^{\circ}{\sim}90^{\circ}$. On the other hand, this relationship was appeared linear to ${\sigma}_c=14.4 I_{s(50)}$ when the bedding angle, $\beta$ is fixed to 90${^{\circ}}$ and this correlation is much different from ${\sigma}c=22 I_{s(50)}, which is generally applied to the rock specimen with no bedding plane in ISRM (1985). The anisotropic strength with different $\beta$ angle shows the shoulder type and this can be suitably modelled by the corrected Ramamurthy'(1993)s equation with the index value of 'n' equal to 3.0.

• 한국디지털정책학회:학술대회논문집
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• 2003.12a
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• pp.147-159
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• 2003

본 연구는 거시경제학의 기초이론인 케인즈 모형을 사용하여 지역의 대학이 지역 경제에서 차지하는 역할이 어느 정도가 되는지 계량적 분석과 설문지를 통한 실증분석을 하였다. 먼저 케인즈의 모형을 사 용한 분석결과, D 대학 학생들은 1994 년$\sim$2002 년까지 연간 1 천억 이상 소득 창출효과를 보였다. 이것은 속초시 총소득의 $15%{\sim}30%$ 이상을 차지하는 상당한 비중이라 할 수 있다. 두 번째 분석으로는 D 대학 학생과 지역주민을 대상으로 한 설문 조사를 하였다. 특히 같은 도내 대학교인 K 대를 대상으로 조정 권 (2002) 의 연구와 그 결과를 비교하였다. 분석결과 D 대학과 K 대는 전반적으로 유사한 결과를 보였지만, 지역주민들은 실제 계량적 분석결과와 달리 지역대학의 경제적 영향력을 과소 평가하는 것으로 나타났다. 이러한 지역주민 (지방자치단체)의 지역대학에 대한 인식의 차이와 이해 부족은 지역대학의 잠재능력을 사장시킬 뿐만 아니라 결국 지역발전의 저해 요인으로 작용한다는 것을 시사하고 있다.