• Journal of the Chungcheong Mathematical Society
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• v.32 no.1
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• pp.87-95
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• 2019

The homothety classes of lattices in a two dimensional vector space over a nonarchimedean local field form a regular tree ${\mathcal{T}}$ of degree q + 1 on which the projective linear group acts naturally where q is the order of the residue field. We show that for any finite regular combinatorial graph of even degree q + 1, there exists a torsion free discrete subgroup ${\Gamma}$ of the projective linear group such that ${\mathcal{T}}/{\Gamma}$ is isomorphic to the graph.

• Journal of Environmental Science International
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• v.17 no.12
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• pp.1315-1324
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• 2008

This study was investigated on the consciousness of middle school students in Jeju city about the environmental education through questionnaire, in order to understand the actual conditions of environmental education and to find out the solutions about them. Middle 'school students responded that environmental education in school was taken at the class for the special activity or voluntary service, not in regular class and was worked as in the form of the field trip. They generally obtain the knowledge and informations on the environmental problems from mass media such as TV, radio and newspaper than from regular environment class in school. And 36.0% of students perceive that environmental education is needed as a regular class and 31.3% of students perceive that the regular class in school is effective to the environmental education. These results suggest that many students are interested in the regular environment class in school. However, the most of students responded that the regular environment class in school is not worked or is not worked at all, suggesting that the environmental education in middle school is not worked effectively. Most of students prefer to take the environment class in the form of observation or field trip, and they think that observation or field trip is more effective to obtain environmental informations. In conclusion, the special activity such as observation or field trip needs to be supplemented to regular environment class in order to improve the environmental education in middle school more effectively.

• Bulletin of the Korean Mathematical Society
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• v.36 no.3
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• pp.503-512
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• 1999

Over a field k, every schur k-algebra is a cyclotomic algebra due to Brauer-Witt theorem. Similarly every projective Schur k-division algebra is itself a radical algebra by Aljadeff-Sonn theorem. We study the two theorems over a certain commutative ring, and prove similar results over regular domain containing a field.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.835-841
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• 2005

실시간 가시화/시각화(Visualization)을 위한 지형 가시화 분야에서의 렌더링 속도 향상은 사용자의 현실감에 있어 중요한 역할을 한다. 본 연구는 Height Field 데이터를 사용한 블록 단위 지형 렌더링 방법에서 이전 프레임 정보를 사용하여 지형 가시화 속도를 향상시키는 방법을 제안한다. Height Field로 표현된 지형을 실시간에 효과적으로 렌더링 할 수 있는 방법으로CLOD(Continuous leveI Of Detail)가 있으며 대표적인 방법으로 Multiresolution TIN(Triangle Irregular Network)과 Regular Grid Method에 기반한 방법들이 있다. 대개의 경우, 지형 데이터는 매우 방대한 크기를 가지고 있어서 실시간으로 렌더링 하는 것이 불가능할 경우가 많다. 따라서 실시간 지형렌더링 에서는 LOD(Level of Detail)관리와 뷰 프러스텀 컬링이 실시간 렌더링 속도 향상을 위한 핵심 사항이 된다. 본 연구에서는 PC 기반에서 효과적으로 지형을 표현하기 위해 기존 Regular Grid Method에 기반한 방법의 가시영역 추출(View Frustum Culling)을 수정하여 실시간 지형 렌더링의 가시 영역 추출(View Frustum Culling)시 기존의 쿼드트리 방식과 함께 이전 프레임에서 블록 단위로 저장된 컬링 정보를 혼용하여 속도를 향상시키는 방법을 상세히 기술 한다.

• Transactions of Materials Processing
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• v.4 no.1
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• pp.59-69
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• 1995

A simple kinematically admissible velocity field is proposed to determine the final-stage extrusion load and the average extruded length in the square-die forward extrusion of regular polygonal-shaped bars from circular billets. From the proposed velocity field, the upper-bound extrusion load and the average extruded length are determined by minimizing the total power consumption with respect to four parameters. Experiments have been carried out with hard solder billets at room temperature. The theoretical predictions of the extrusion load are in good agreements with the experimental results and there is generally reason able agreement in average extruded length between theory and experiment.

• Bulletin of the Korean Mathematical Society
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• v.54 no.2
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• pp.497-505
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• 2017

The rank over a finite field of the adjacency matrix of a directed strongly regular graph is studied, with some applications to the construction of linear codes. Three techniques are used: code orthogonality, adjacency matrix determinant, and adjacency matrix spectrum.

• East Asian mathematical journal
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• v.33 no.3
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• pp.309-315
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• 2017

In this paper, we investigate the regularities of the hyper-complex valued functions of the split quaternion variables. We define several differential operators for the split qunaternionic function. We research several left split regular functions for each differential operators. We also investigate split harmonic functions. And we find the corresponding Cauchy-Riemann system and the corresponding Cauchy theorem for each regular functions on the split quaternion field.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.41-53
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• 2006

This experimental study investigated the flow characteristics for regular waves passing a rectangular floating structure in a two-dimensional wave tank. The particle image velocimetry (PIV) was employed to obtain the velocity field in the vicinity of the structure. The phase average was used to extract the mean flow and turbulence property from repeated instantaneous PIV velocity profiles. The mean velocity field represented the vortex generation and evolution on both sides of the structure. The turbulence properties, including the turbulence length scale and the turbulent kinetic energy budget were investigated to characterize the flow interaction between the regular wave and the structure. The results shaw the vortex generated near the structure corners, which are known as the eddy-making damping or viscous damping. However, the vortex induced by the wave is longer than the roll natural period of the structure, which presents the phenomena opposing the roll damping effect; that is, the vortex may increase the roll motion under the wave condition longer than the roll natural period.

• Journal of the Korean Mathematical Society
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• v.48 no.6
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• pp.1171-1187
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• 2011

Silverman [14] proved a height inequality for a jointly regular family of rational maps and the author [10] improved it for a jointly regular pair. In this paper, we provide the same improvement for a jointly regular family: let h : ${\mathbb{P}}_{\mathbb{Q}}^n{\rightarrow}{{\mathbb{R}}$ be the logarithmic absolute height on the projective space, let r(f) be the D-ratio of a rational map f which is de ned in [10] and let {$f_1,{\ldots},f_k|f_l:\mathbb{A}^n{\rightarrow}\mathbb{A}^n$} bbe finite set of polynomial maps which is defined over a number field K. If the intersection of the indeterminacy loci of $f_1,{\ldots},f_k$ is empty, then there is a constant C such that $ \sum\limits_{l=1}^k\frac{1}{def\;f_\iota}h(f_\iota(P))>(1+\frac{1}{r})f(P)-C$ for all $P{\in}\mathbb{A}^n$ where r= $max_{\iota=1},{\ldots},k(r(f_l))$.

• Bulletin of the Korean Mathematical Society
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• v.42 no.4
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• pp.807-815
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• 2005

Let R be a ring with identity, X the set of all nonzero, nonunits of Rand G the group of all units of R. We will consider two group actions on X by G, the regular action and the conjugate action. In this paper, by investigating two group actions we can have some results as follows: First, if G is a finitely generated abelian group, then the orbit O(x) under the regular action on X by G is finite for all nilpotents x $\in$ X. Secondly, if F is a field in which 2 is a unit and F $\backslash\;\{0\}$ is a finitley generated abelian group, then F is finite. Finally, if G in a unit-regular ring R is a torsion group and 2 is a unit in R, then the conjugate action on X by G is trivial if and only if G is abelian if and only if R is commutative.