• 대한수학회지
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• 제45권4호
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• pp.965-976
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• 2008

In this article, we constructively prove that on a surface S with genus g$\geq$2, there exit maximal geodesic laminations with 7g-7,...,9g-9 leaves. Thus, S can have ideal cell-decompositions (i.e., S can be (ideally) triangulated by maximal geodesic laminations) with 7g-7,...,9g-9 (ideal) 1-cells. Once there is a triangulation for a compact surface, the Euler characteristic for the surface can be calculated as the alternating sum F-E+V, where F, E, and V denote the number of faces, edges, and vertices, respectively. We also prove that the same formula holds for the ideal cell decompositions.

• 대한수학회보
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• 제46권5호
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• pp.941-947
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• 2009

Let q be a power of 16. Every polynomial $P\in\mathbb{F}_q$[t] is a strict sum $P=A^2+A+B^3+C^3+D^3+E^3$. The values of A,B,C,D,E are effectively obtained from the coefficients of P. The proof uses the new result that every polynomial $Q\in\mathbb{F}_q$[t], satisfying the necessary condition that the constant term Q(0) has zero trace, has a strict and effective representation as: $Q=F^2+F+tG^2$. This improves for such q's and such Q's a result of Gallardo, Rahavandrainy, and Vaserstein that requires three polynomials F,G,H for the strict representation $Q=F^2$+F+GH. Observe that the latter representation may be considered as an analogue in characteristic 2 of the strict representation of a polynomial Q by three squares in odd characteristic.

• 한국철도학회논문집
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• 제9권6호
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• pp.705-710
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• 2006

The railway has been developed largely by the characteristic factors of the railway through change of the society and culture. The railway trends has been changing from instinctive methods to settle the mass transport of the early days, to sensitive methods to pursue the railway culture centering around human being. As dividing by period according to the changes of railway trends into the external nation, there are to analyze the development history of the railway design. Accordingly each nation (United Kingdom, Germany, France, Japan) and the style's change, to confirm the changes into the design applied in society and culture needs, and to analyze by a year in changes of the environment and the railway history from the 1800's to 2005, so there contribute in the development of railway design to present the paradigm of the future railway by analyzing the trend according to the changes of railway design and the life environment in this paper.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 추계 학술대회논문집
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• pp.48-58
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• 1999

The Characteristic Flux Difference Splitting (CFDS) scheme designed to adapt the characteristic boundary conditions at the wall and inflow/outflow boundary planes satisfies Roe's property U, although the CFDS Jacobian matrix is decomposed by a product of elaborate transformation matrices and explicit eigenvalue matrix. When the CFDS algorithm, thus a variant of Roe's scheme, is applied straightforwardly to hypersonic flows over a blunt body, the strong bow shock gradually breaks down near the stagnation point. This numerical instability is widely observed by many researchers employing flux-difference method, known in the literature as the carbuncle phenomenon. Many remedies have been proposed and resulted in partial cures. When the idea of Sanders et al. which identifies the minimum eigenvalues near the discontinuity present is applied to CFDS method, it is shown that the instability problem can be controlled successfully. A few flux splitting methods have also been tested and results are compared against the Nakamori's Mach 8 blunt body flow.

• 한국전산유체공학회지
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• 제14권3호
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• pp.25-32
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• 2009

The present paper focuses on the analysis of aero-acoustics characteristic by appling different four boundary conditions. The high-order and high-resolution numerical schemes are used for discrete accurate computation of compressible flow. The four boundary conditions include extrapolation, characteristic boundary condition, zonal characteristic boundary condition. These boundary conditions are applied to the computation of two dimensional circular cylinder flows with Mach number of 0.3 and Reynolds number of 400. The computation results are validated against measurement data and other computation results for the Strouhal frequency of vortex shedding, the mean drag coefficient and root-mean-square lift for the unsteady periodic flow regime. The characteristics of secondary frequency is predicted by three kinds of boundary conditions.

• Communications for Statistical Applications and Methods
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• 제20권6호
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• pp.475-480
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• 2013

The surplus process in a risk model is stochastically analyzed. We obtain the characteristic function of the level of the surplus at a finite time, by establishing and solving an integro-differential equation for the distribution function of the surplus. The characteristic function of the stationary distribution of the surplus is also obtained by assuming that an investment of the surplus is made to other business when the surplus reaches a sufficient level. As a consequence, we obtain the first and second moments of the surplus both at a finite time and in an infinite horizon (in the long-run).

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.632-637
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• 2016

This study shows what difference would be made to the aerodynamic characteristic with different thickness ratio of the same airfoil, Eppler 387, at low Reynolds number, at the angle of attack of $0^{\circ}$. Konkuk Univ.'s airfoil has a bigger thickness ratio than that of the original Eppler 387 airfoil. The reason for the thicker camber is a Pt 100 ohm heater mounted inside the Konkuk Univ.'s airfoil and this was assumed to make some differences to aerodynamic characteristic. The comparison of these two airfoils' CFD data, provided by EDSION_CFD, with real experiment that had been made in subsonic wind tunnel at Konkuk Univ. is done. A finer result would come out if the complement of the homogeneity of the wind tunnel's fluid is done in the future.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.220-222
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• 2004

The piezoelectric ceramics for a step-up piezoelectric transformer are desired large electromechanical coupling factor, high mechanical quality factor and good characteristic resonance frequency. In this study, the empirical formula of specimens is used $0.9Pb(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS). The piezoelectric and dielectric characteristic are investigated by sintering temperature and value of x as functions of $Ti^{2+}$, $Zi^{2+}$ mol rate. MPB(morphotropic phase boundary) is defined in the x=0.522. Because it is appeared to the best piezoelectric and dielectric characteristic in the x=0.522, it can be application of step-up transformer.

• 대한한방소아과학회지
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• 제16권2호
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• pp.101-110
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• 2002

The common cold is the most common pediatric infectious disease and occupies a great number of outpatients in oriental pediatrics. Because children's common cold has characteristic symptoms, we studied 276 children suffering from common cold Oriental Medicine Hospital in Kyungsan University and analyzed sex, age, chief complaints, characteristic symptoms.(period : summer 2001. 6.1.-2001.8.31, winter 2001.12.1-2002. 2. 28) The results were as follows : 1. Male to female ratios were 17: 1 in summer, 1.2: 1 in winter, 1.4: 1 in total 2. Age distribution of children from 0 to 1 was 20.29%, from 1 to 3 was 39.49%, from 3 to 6 was 32.97%, from 6 to 10 was 7.27%, over 10 was 0%, from 0 to 6 was 92.75%. 3. Frequency of chief complaints In summer : cough was 22.28%, nasal discharge was 18.39%, fever was 16.58%, secretion and sputum were 14.50%, sweating was 6.99%, nausea or vomitting were 4.92% etc. In winter : cough was 24.20%, nasal discharge was 18.03%, secretion and sputum were 16.43%, occlusion of nares was 11.64%, fever was 9.58%, nausea or vomitting were 3.88% etc. Frequency of chief complaints has seasonal difference. 4. Children's common cold has characteristic symptoms and seasonal difference. 5. Children's common cold has characteristic clinical subtype.

• 복식문화연구
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• 제17권5호
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• pp.733-745
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• 2009

The contra-sexual phenomenon that is recently focused is one of the new factors, which is focused when explaining the life style of progressive woman's image and it is creating cultural category. Moreover, the contra sexual people that are rising as new consuming subjects are not simple primary consumers but their shopping culture and cultural tastes are giving effects to many people. Because of the tendency, marketer of consuming industry are making efforts to predict the changes of contra-sexual people's shopping habits and tastes. Therefore, it is necessary to grasp contra-sexual phenomenon and research the fashion design aiming at that in order to predict woman's fashion image in the future. Therefore, the study considered concept and characteristic of contra-sexual phenomenon and surveyed its example in the popular culture. And, the study analyzed the formative characteristic of contra-sexual fashion shown in the public cultures such as drama and movie. On the basis of the result, design was suggested by reflecting contra-sexual fashion characteristic under the concept of 'Urban Splendor'. From the results above, it was possible to grasp the concept and characteristic of contra-sexual phenomenon, which appeared as a trend and understand new woman's image and the fashion that has changed because of it. It is considered that the establishment of the foundation of contra-sexual phenomenon, which plays as an important variable in woman's fashion, fashion accessory, cosmetic and advertisement field but it is hard to clarify, by analyzing the work aiming at contra-sexual phenomenon will be helpful for predicting the change of woman's fashion in the future.