• 한국경영과학회지
• /
• 제41권2호
• /
• pp.17-33
• /
• 2016

Clustering is one of the leading methods to analyze big data and is used in many different fields. This study deals with Clustering Validity Index (CVI) to verify the effectiveness of clustering results. We compare the performance of CVIs with business applications of various field. In this study, the used CVIs for comparing performance are DU, CH, DB, SVDU, SVCH, and SVDB. The first three CVIs are well-known ones in the existing research and the last three CVIs are based on support vector data description. It has been verified with outstanding performance and qualified as the application ability of CVIs based on support vector data description.

• 한국기록관리학회지
• /
• 제16권1호
• /
• pp.223-245
• /
• 2016

ICA의 CBPS에서는 지난 20여년간 ISAD(G)와 ISAAR(CPF)와 같은 기록물 기술표준을 개발해 왔다. 그리고 최근에 ICA는 새로운 조직인 EGAD를 구성하여 기존의 기록물 기술표준을 통합하고 있다. EGAD가 개발 중인 기술표준의 명칭은 'Record in Context'(RIC)이며, 개념모형과 온톨로지로 구성된다. 그런데 EGAD는 RIC의 개발을 위해 ICA의 기존 기록물 기술표준뿐 아니라, 호주나 스페인, 핀란드에서 최근에 개정된 기록물 기술표준과 박물관 및 도서관 분야의 협력을 통해 개발된 FRBRoo도 참고하였다. 이에 본 연구에서는 국제적인 기록물 기술표준의 개정 동향을 살펴보고, 이와 같은 동향이 국내의 기록물 기술표준의 발전에 주는 시사점을 도출하였다. 기록물의 기술표준은 표준화된 기술요소의 정확한 입력지침을 넘어서, 상위의 개념틀을 제공하고, 이를 바탕으로 유연한 기록물 기술과 데이터 공유가 용이한 온톨로지를 제공하기 위해 개선되고 있었다. 앞으로는 국내의 기록물 기술표준도 정보환경의 변화를 수용하고, 문화유산관리기관 간의 협력을 증진시킬 수 있는 방향으로 발전해야 할 것이다.

• 대한조선학회논문집
• /
• 제41권1호
• /
• pp.23-30
• /
• 2004

In the Lagrangian vortex particle method based on the vorticity-velocity formulation for solving the incompressible Navier-Stokes equations, a numerical scheme for calculating pressure fields is presented. Implementation of the numerical method is directly connected with the well-established surface panel methods, just by dealing with the dynamic coupling among vorticity field. Assuming the vorticity and the velocity fields are to be calculated in time domain analysis, the pressure calculation for a complete set of solution at present time step is performed in a similar way to the one used in the Eulerian description. For a validation of the present method, we illustrate the early development of the viscous flow about an impulsive started circular cylinder for Reynolds number 550. The comparative study with the Eulerian finite Volume method provides an extensive understanding and application of the mesh-free Lagrangian vortex methods for numerical simulation of viscous flows around arbitrary bodies of general shape.

• Wind and Structures
• /
• 제29권6호
• /
• pp.389-403
• /
• 2019

In this study, two original spectral representations of stationary stochastic fields, say the continuous proper orthogonal decomposition (CPOD) and the frequency-wavenumber spectral representation (FWSR), are derived from the Fourier-Stieltjes integral at first. Meanwhile, the relations between the above two representations are discussed detailedly. However, the most widely used conventional Monte Carlo schemes associated with the two representations still leave two difficulties unsolved, say the high dimension of random variables and the incompleteness of probability with respect to the generated sample functions of the stochastic fields. In view of this, a dimension-reduction model involving merely one elementary random variable with the representative points set owing assigned probabilities is proposed, realizing the refined description of probability characteristics for the stochastic fields by generating just several hundred representative samples with assigned probabilities. In addition, for the purpose of overcoming the defects of simulation efficiency and accuracy in the FWSR, an improved scheme of non-uniform wavenumber intervals is suggested. Finally, the Fast Fourier Transform (FFT) algorithm is adopted to further enhance the simulation efficiency of the horizontal stochastic wind velocity fields. Numerical examplesfully reveal the validity and superiorityof the proposed methods.

• Wind and Structures
• /
• 제16권5호
• /
• pp.433-455
• /
• 2013

A phase delay spectrum model towards the representation of spatial coherence of stochastic wind fields is proposed. Different from the classical coherence functions used in the spectral representation methods, the model is derived from the comprehensive description of coherence of fluctuating wind speeds and from the thorough analysis of physical accounts of random factors affecting phase delay, building up a consistent mapping between the simulated fluctuating wind speeds and the basic random variables. It thus includes complete probabilistic information of spatial stochastic wind fields. This treatment prompts a ready and succinct scheme for the simulation of fluctuating wind speeds, and provides a new perspective to the accurate assessment of dynamic reliability of wind-induced structures. Numerical investigations and comparative studies indicate that the developed model is of rationality and of applicability which matches well with the measured data at spatial points of wind fields, whereby the phase spectra at defined datum mark and objective point are feasibly obtained using the numerical scheme associated with the starting-time of phase evolution. In conjunction with the stochastic Fourier amplitude spectrum that we developed previously, the time history of fluctuating wind speeds at any spatial points of wind fields can be readily simulated.

• Journal of Species Research
• /
• 제8권3호
• /
• pp.283-287
• /
• 2019

Pardosa pseudolaevitarsis n. sp. and Hygrolycosa umidicola Tanaka, 1978 belonging to Lycosidae are described from Korea. To date, fourteen species in the genus Pardosa C. L. Koch, 1847 have been described from Korea. H. umidicola belongs to Hygrolycosa Dahl, 1908 was once described from Korea, but the previous description of this species could not provide adequate scientific evidence for adding H. umidicola to the Korean spider fauna. Pardosa pseudolaevitarsis n. sp. is similar to P. laevitarsis Tanaka & Suwa, 1986 in the shape of its epigyne and palp, but can be distinguished by the followings: epigynal atrium small; spermathecae extending to the end of atrium; shape, location and orientation of fertilization duct in epigyne and internal genitalia; blunt basal spur of median apophysis in palp; number, shape and arrangement cheliceral teeth on both margins. Both species were collected using pitfall traps on a ridge between rice fields and seem to prefer habitats with relatively high humidity.

• 대한기계학회논문집A
• /
• 제24권1호
• /
• pp.144-155
• /
• 2000

초록 The validity, of a single parameter such as stress intensity, factor K or J-integral in traditional fracture mechanics depends strongly on the geometry, and loading condition. Therefore the second parameter like T-stress measuring the stress constraint is additionally needed to characterize the general crack-tip fields. While many, research works have been done to verify, the J-T description of elastic-plastic crack-tip stress fields in plane strain specimens, limited works (especially. for bimaterials) have been performed to describe the structural surface crack-front stress fields with the two parameters. On this background, via detailed three dimensional finite element analyses for surface-cracked plates and straight pipes of homogeneous materials and bimaterials under various loadings, we investigate the extended validity or limitation of the two parameter approach. We here first develop a full 3D mesh generating program for semi-elliptical surface cracks, and calculate elastic T-stress from the obtained finite element stress field. Comparing the J-T predictions to the elastic-plastic stresses from 3D finite element analyses. we then confirm the extended validity of fracture mechanics methodology based on the J-T two parameters in characterizing the surface crack-front fields of welded plates and pipes under various loadings.

• 기술혁신연구
• /
• 제13권1호
• /
• pp.169-191
• /
• 2005

By analyzing a national survey of public understanding of science and technology, this paper attempts to examine public perceptions of scientists and engineers in Korea. A special attention is given to the gap in the view of scientists and engineers across generation, gender, and class fields (or major fields). This paper shows that generation has the strongest effect on public perceptions of scientists and engineers among all the socio-demographic factors examined in this study. Those over 50 are more likely to have the conventional idealized images of scientists and the stereotypical negative images of scientists simultaneously, while the 20s are less likely to accept the idealized image of scientists. The survey result thus may suggest that the younger generation began to depart from a patriotic and moral description of scientists and engineers-for the younger generation, science and engineering is losing moral respect but becomes perceived as an ordinary occupation. Contrary to the popular belief, however, gender has little effect on public perceptions of scientists and engineers. This finding questions the assertion that female students possess more negative attitudes toward scientists and engineers than male students, and thus are reluctant to develop careers related to science and engineering. By uncovering that class fields (or major areas) have no effect on the image of scientists, this study also call into question the assertion in the science wars that the inadequate appreciation of science particularly among those who do not major in science and engineering is responsible for inadequate support for science and technology.

• 대한수학회보
• /
• 제51권6호
• /
• pp.1605-1614
• /
• 2014

In continuation to the investigation initiated by Ferraz, Goodaire and Milies in [4], we provide an explicit description for the Wedderburn decomposition of finite semisimple group algebras of the class of finite groups G, such that $$G/Z(G){\simeq_-}C_2{\times}C_2$$, where Z(G) denotes the center of G.

• 한국의사학회지
• /
• 제21권1호
• /
• pp.77-81
• /
• 2008

상과, also called 정골과 in Korea, was a subclass of External Medicine. Of the many sub-fields belonging to Traditional Korean Medicine, 상과 specializes in technological aspects: therefore its preservation and accedence is emphasized. Traditional 상과학 primarily bases clinical diagnosis and treatment on 수기법. Tang dynasty 藺道人's "仙授理傷續斷秘方, the first medical text specializing in 상과, includes detailed description of the 復位, 夾板固定, training, and medicinal treatment stages of treating bone fracture. Jin dynasty 葛洪's "肘後備急方" introduces a fracture treatment method through 竹夾板固定.