• Korean Journal of Mathematics
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• 제32권2호
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• pp.259-284
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• 2024

In present study, we introduce ruled surfaces whose base curve is the Salkowski curve in Euclidean 3-space and whose generating lines consist of the Frenet vectors of this curve (tangent, principal normal and binormal vectors). Then, we produce regular surfaces from a vector with real coefficients, which is a linear combination of these vectors, and we examine some special cases for these surfaces. Moreover, we present some geometric properties and graphics of all these surfaces.

• 한국실내디자인학회논문집
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• 제14호
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• pp.42-54
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• 1998

This study aims to analyze needs for living space of residents in a farming retirement community In this study a survey was performed about desire for living space and aesthetic aspects of housing environment. Results of the study are as follows; 1. Most residents desire permanently formed dwelling unit rather than assembled temporary structure so that they comfortable in noise-prevented space. 2 The retirement community residents do not desperately prefer individually separated room because open space provides better observsation function for emergencies. 3. They hope their dwelling units are grouped like regular neighborhood and the units have traditional designs such conventional kitchen and sink and wooden floor. Finally in this study it is proposed that Korean rural retirement community be established with maximum use conventional dwelling resources so that the residents benefit old fashioned living tradition even in the recently moved retirement society.

• 대한수학회논문집
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• 제27권1호
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• pp.201-205
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• 2012

A space X is cs-starcompact if for every open cover $\mathcal{U}$ of X, there exists a convergent sequence S of X such that St(S, $\mathcal{U}$) = X, where $St(S,\mathcal{U})\;=\; \cup\{U{\in}\mathcal{U}:U{\cap}S{\neq}\phi\}$. In this paper, we prove the following statements: (1) There exists a Tychonoff cs-starcompact space having a regular-closed subset which is not cs-starcompact; (2) There exists a Hausdorff cs-starcompact space with arbitrary large extent; (3) Every Hausdorff centered-Lindel$\ddot{o}$f space can be embedded in a Hausdorff cs-starcompact space as a closed subspace.

• 한국항행학회논문지
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• 제13권6호
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• pp.984-990
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• 2009

하프토닝은 단색으로 다양한 계조의 색단계를 표현하는 방법으로 인쇄 매체와 같은 분야에서 제한된 색으로 다양한 톤을 표현할 수 있도록 해주는 매우 중요한 영상처리기법이다. 본 논문에서는 공간채움곡선 (Space-Filling Curve)에 의한 하프토닝 방법의 대안으로 미로 생성 알고리즘에 기반한 새로운 하프토닝 방법을 제안한다. 기존의 공간채움곡선에 의한 오류 확산방법은 규칙적인 스캔 패턴으로 인해 해프토닝의 결과에도 규칙적인 패턴이 발생한다. 이러한 부분을 개선하기 위해 공간채움곡선 대신 미로의 경로를 사용함으로써 규칙적인 패턴을 제거하였다.

• 대한수학회보
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• 제37권1호
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• pp.171-179
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• 2000

We prove the following: (1) For a Hausdorff space X, the hyperspace K(X) of compact subsets of X is hemicompact if and only if X is hemicompact. (2) For a regular space X, the hyperspace $C_K(X)$ of subcontinua of X is hemicompact (hemiconnected) if and only if X is hemicompact (hemiconnected). (3) For a locally compact Hausdorff space X, each open set in X is hemicompact if and only if each basic open set in the hyperspace K(X) is hemicompact. (4) For a connected, locally connected, locally compact Hausdorff space X, K(X) is hemiconnected if and only if X is hemiconnected.

• 대한수학회논문집
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• 제22권4호
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• pp.569-573
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• 2007

In this note, we construct an example of a Hausdorff K-starcompact (hence, $1\frac{1}{2}$-star-compact) space X having a regular closed $G_{\delta}-subset$ which is not $1\frac{1}{2}$-starcompact (hence, not K-starcompact).

• Kyungpook Mathematical Journal
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• 제52권3호
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• pp.265-269
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• 2012

In this paper, we prove the following theorem which gives a characterization of $M_1$-spaces by g-function.

• ETRI Journal
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• 제26권6호
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• pp.622-634
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• 2004

In this paper, we discuss the design problem and the robustness of space-frequency trellis codes (SFTCs) for multiple input multiple output, orthogonal frequency division multiplexing (MIMO-OFDM) systems. We find that the channel constructed by the consecutive subcarriers of an OFDM block is a correlated fading channel with the regular correlation function of the number and time delay of the multipaths. By introducing the first-order auto-regressive model, we decompose the correlated fading channel into two independent components: a slow fading channel and a fast fading channel. Therefore, the design problem of SFTCs is converted into the joint design in both slow fading and fast fading channels. We present an improved design criterion for SFTCs. We also show that the SFTCs designed according to our criterion are robust against the multipath time delays. Simulation results are provided to confirm our theoretic analysis.

• 천문학회보
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• 제40권1호
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• pp.86.4-87
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• 2015

We will soon complete the installation of 1m telescope at Deokheung Optical Astronomy Observatory (DOAO), National Youth Space Center (NYSC). Before the test observation with NYSC 1m telescope, we present the specs of the 1M telescope and observational conditions of the DOAO site, such as the seeing data at DOAO and the atmospheric extinction coefficients obtained from the observations of standard stars and stellar clusters with 120mm and 150mm refractor in 2014. Since atmospheric extinction coefficients depend on the observational instruments as well as the atmospheric conditions of the site, the improved data with NYSC 1m telescope will be obtained right after the completion of 1M telescope installation. We are planning to invite all astronomers to use 1m telescope for their sciences via regular proposal processes in this year.

• 천문학회보
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• 제42권1호
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• pp.47.2-47.2
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• 2017

We present the results of astrometric observations using water masers around a semi-regular variable star R Crt. The observations were carried out for two years with the Korean VLBI Network (KVN). The absolute positions of the water masers from R Crt are successfully obtained at 10 epochs in total. By tracking the positions of the water maser emission, we directly measured the annual parallax and distance of R Crt. The measured distance to R Crt enables us to estimate the actual 3D velocity of water masers around R Crt. Our research suggests the possibility of performing astrometric studies with the KVN. As a next step, we are going to enhance the astrometric accuracy by observing SiO masers.