• 응용통계연구
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• 제17권3호
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• pp.519-533
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• 2004

본 연구에서는 베리오그램 추정을 통한 공간 종속성 추정방법에 있어서 의사우도 사용 방법을 설명하고, 모의실험을 통하여 전통적으로 사용되는 다른 방법들과 그 특성을 비교하고자 한다. 의사우도를 이용한 공간 종속 추정방법들은 그 통계적 성질이 우수할 뿐만 아니라, 전통적인 방법들에서 요구되어지는 관측치가 갖는 래그(lag)들을 미리 지정된 래그로 그룹화하는 과정이 필요 없어서 활용상의 우수성도 함께 가지고 있다. 또한, 이 방법에 대한 로버스트 방법을 개발하고 그 특성을 알아보고자 한다.

• 대한수학회논문집
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• 제14권1호
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• pp.135-146
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• 1999

In this paper, we introduce the (4k-1)-diagonal algebra $Alg{\iota}(\array{4k-1\\\infty}\)$ and investigate the necessary and sufficient condition that isomorphisms of $Alg{\iota}(\array{4k-1\\\infty}\)$ are quasi-spatial.

• 한국통신학회논문지
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• 제41권4호
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• pp.404-414
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• 2016

So called quaternary quasi-orthogonal sequence spatial modulation (Q-QOS-SM) has been presented with an advantage of improved throughputs compared to the conventional SM and generalized spatial modulation (GSM) by virtue of a larger set size of QOSs and its minimized correlation value between these QOSs. However the Q-QOS-SM has been originally invented for limited transmit antennas of only powers of two. In this paper, by extending the Q-QOS-SM to any number of transmit antennas, we propose a generalized Q-QOS-SM, referred as G-QO-SM. Unlike the conventional Q-QOS-SM using the Q-QOSs of length of any power of two, the proposed G-QO-SM is constructed based on the Q-QOSs of only the lengths of 2 and 4. The proposed scheme guarantees the transmission of the total $N_t$ spatial bits with $N_t$ transmit antennas, and thus achieves greatly higher throughputs than the other existing schemes including the SM, GSM, Q-QOS-SM, Quadrature-SM, and Enhanced-SM. The performance improvements of the proposed G-QO-SM is justified by comparing the analytically derived BER upper bounds and also the exact Monte Carlo simulation results.

• 한국강구조학회 논문집
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• 제13권6호
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• pp.661-672
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• 2001

본 연구는 Arc-length method를 이용한 복합재료 공간 구조물의 대변형 거동의 관찰에 관한 것이다. 비선형 평형경로의 각각의 하중단계에서 자동적으로 Arc-length 크기를 변화시켜 하중-변위 관계곡선을 추적할 수 있도록 하였다. 복합재료 공간 트러스의 점탄성 해석은 quasi-elastic 방법을 사용해 탄성해를 구하였다. Micro Mechanical Materials Modeling 방법을 사용하여 탄성계수를 결정하였고 하중조합에 따른 비선형 하중-변위 곡선을 추적하였다. 본 연구의 효과를 검증하기 위하여 그물형 공간 트러스를 다른 방법의 결과들과 비교하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.751-756
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• 2002

Since the operation of the first satellite-based navigation services, satellite positioning has played an increasing role in both surveying and navigation, and has become an indispensable tool for precise relative positioning. However, in some situations, e.g. at a low angle of elevation, the use of satellites for navigation is seriously restricted because obstacles like buildings and mountains can block signals. As a mean to resolve this problem, the quasi-zenith satellite system has been proposed as a next-generation satellite navigation system. Quasi-zenith satellite is a system which simultaneously deploys several satellites in a quasi-zenith geostationary orbit so that one of the satellites always stay close to the zenith if viewed from a specific point on the ground of East Asia. Thus, if a position measurement function compatible with GPS is installed in the quasi-zenith and stationary satellites, and these satellites are utilized together with the GPS, four satellites can be accessed simultaneously nearly all day long and a substantial improvement in position measurement, especially in metropolitan areas, can be achieved. The purpose of this paper is to evaluate the effectiveness of quasi-zenith satellite system on positioning accuracy improvement through simulation by using precise orbital information of the satellites and a three-Dimensional digital map. Through this simulation system, it is possible to calculate the number of simultaneously visible satellites and available area of the positioning without the need of actual observation.

• 한국수자원학회논문집
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• 제36권6호
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• pp.961-969
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• 2003

토양수분 분포의 시공간적인 예측을 위하여 유사 동력학 상태의 습윤지수 계산과정을 정리하였고, 우량 자료를 회귀적분한 동력학적 습윤지수의 계산 알고리즘을 개발하였다. 설마천 유역의 수치고도 모형과 2년간의 우량자료를 활용하여 동력학적 상태의 습윤지수의 시ㆍ공간적인 거동을 분석하였다. 공간적인 거동은 동력학적인 습윤지수가 유사 동력학적 상태나 정적인 습윤지수와 비교하여 흐름분산 특성이 강조된 분포특성을 보여주었다. 통계적인 특성으로는 시간이 경과함에 따라 유사동력학적 습윤지수나 동력학적 습윤지수 모두 정상상태 습윤지수에 근접하나, 동력학적 습윤지수의 경우 두 개의 상이한 분포특성이 나타났다.

• 한국통신학회논문지
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• 제40권4호
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• pp.637-645
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• 2015

Recently, a spatial modulation (SM) scheme achieving high throughput based on quaternary quasi-orthogonal sequences (Q-QOSs), referred to as Q-QOS-SM, is presented for $N_t=2^n(n=1,2,{\cdots})$ transmit antennas. In this paper, based on the design approach of the conventional Q-QOS-SM, new improved QO-SM (I-QO-SM) schemes are proposed for 8 transmit antennas. The new schemes employ Q-QOSs of length 4 or 2 unlike of 8 in the original one, which guarantees more information bits to be allocated for antenna index parts compared to the conventional Q-QOS-SM. By computer simulation results, the proposed scheme are shown to enjoy much higher throughputs compared to the conventional other SM schemes for all simulation environments. Finally, we also examine and compare analytically the performances of the new and conventional SM schemes by calculating upper-bounds on BER performance.

• Journal of Computational Design and Engineering
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• 제1권2호
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• pp.79-87
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• 2014

Voronoi diagrams are powerful for solving spatial problems among particles and have been used in many disciplines of science and engineering. In particular, the Voronoi diagram of three-dimensional spheres, also called the additively-weighted Voronoi diagram, has proven its powerful capabilities for solving the spatial reasoning problems for the arrangement of atoms in both molecular biology and material sciences. In order to solve application problems, the dual structure, called the quasi-triangulation, and its derivative structure, called the beta-complex, are frequently used with the Voronoi diagram itself. However, the Voronoi diagram, the quasi-triangulation, and the beta-complexes are sometimes regarded as somewhat difficult for ordinary users to understand. This paper presents the two-dimensional counterparts of their definitions and introduce the BetaConcept program which implements the theory so that users can easily learn the powerful concept and capabilities of these constructs in a plane. The BetaConcept program was implemented in the standard C++ language with MFC and OpenGL and freely available at Voronoi Diagram Research Center (http://voronoi.hanyang.ac.kr).

• Spatial Information Research
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• 제13권1호
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• pp.43-53
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• 2005

본 연구에서는 폐쇄성 수역에 있어서 비점 오염원의 모델링 및 적정 수환경 관리방안에 대하여 고찰하였다 공간적으로 분포하는 각종 환경정보를 효과적으로 얻기 위하여 GIS데이터(contour data)를 이용하였다. 등고선 데이터로부터 소유역 및 하도망을 자동적으로 도출하였으며, 준 수치고도모델(Quasi Digital Elevation Model)을 모형화함으로써 유역으로부터의 질소 오염물질 유출량을 해석하였다. 본 모형은 실측자료를 토대로 유효화하였다. GIS와 연계한 본 모형은 수역의 오염현황을 고려한 유역의 비점 오염원유출 분석에 효과적이며, 향후 수 환경 관리에 적절하게 이용될 것으로 기대한다.

• Structural Engineering and Mechanics
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• 제36권1호
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• pp.111-127
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• 2010

This paper studies the effects of spatially varying ground motions on the responses of a bridge frame located on a canyon site. Compared to the spatial ground motions on a uniform flat site, which is the usual assumptions in the analysis of spatial ground motion variation effects on structures, the spatial ground motions at different locations on surface of a canyon site have different intensities owing to local site amplifications, besides the loss of coherency and phase difference. In the proposed approach, the spatial ground motions are modelled in two steps. Firstly, the base rock motions are assumed to have the same intensity and are modelled with a filtered Tajimi-Kanai power spectral density function and an empirical spatial ground motion coherency loss function. Then, power spectral density function of ground motion on surface of the canyon site is derived by considering the site amplification effect based on the one dimensional seismic wave propagation theory. Dynamic, quasi-static and total responses of the model structure to various cases of spatially varying ground motions are estimated. For comparison, responses to uniform ground motion, to spatial ground motions without considering local site effects, to spatial ground motions without considering coherency loss or phase shift are also calculated. Discussions on the ground motion spatial variation and local soil site amplification effects on structural responses are made. In particular, the effects of neglecting the site amplifications in the analysis as adopted in most studies of spatial ground motion effect on structural responses are highlighted.