• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.279-289
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• 2006

The reconstruction of low dimension nonlinear behavior from the hydrologic time series has been an active area of research in the last decade. In this study, we present the applications of a powerful state space reconstruction methodology using the method of Support Vector Machines (SVM) to the Great Salt Lake (GSL) volume. SVMs are machine learning systems that use a hypothesis space of linear functions in a Kernel induced higher dimensional feature space. SVMs are optimized by minimizing a bound on a generalized error (risk) measure, rather than just the mean square error over a training set. The utility of this SVM regression approach is demonstrated through applications to the short term forecasts of the biweekly GSL volume. The SVM based reconstruction is used to develop time series forecasts for multiple lead times ranging from the period of two weeks to several months. The reliability of the algorithm in learning and forecasting the dynamics is tested using split sample sensitivity analyses, with a particular interest in forecasting extreme states. Unlike previously reported methodologies, SVMs are able to extract the dynamics using only a few past observed data points (Support Vectors, SV) out of the training examples. Considering statistical measures, the prediction model based on SVM demonstrated encouraging and promising results in a short-term prediction. Thus, the SVM method presented in this study suggests a competitive methodology for the forecast of hydrologic time series.

• Journal of the Korean Geographical Society
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• v.31 no.3
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• pp.542-557
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• 1996

경제적인 풍요가 어느정도 이루어지면서 깨끗한 도시환경속에서 삶을 누리고자 하는 욕구도 증가되었다. 이를 반영하듯이 최근들어 환경에 대한 시민들의 관심이 어느때 보다 더욱 커져만 가고 있다. 이와 더불어 도시계획적 흐름도 물적계획에서 비물적계획인 인간중심 위주의 가치관으로 전환되고 있으며, 공원녹지체계의 정립, 도시경관관리방안, 자전거도로의 도입, 보행자도로의 계획과 설계, 대중교통의 활성화 등 많은 환경친화적 프로젝트들이 수행되어져 왔다. 본 연구에서도 기존의 주요 보행자공간으로 다루어져 온 보도공간에 대하여 조사연구하였으며, 도심의 외곽에 위치하고는 있지만 대구시의 남북을 관통하는 주요간선도로변에 접해 있고 보행량에 비해 보도가 지나치게 넓어 비효율적인 토지이용을 보이는 보도공간을 대상으로 하였다. 특히 도심의 외곽지 보도에 관한 연구는 통행량이 많은 도심지의 상업지나 주택지의 보도에 밀려 상대적으로 소홀히 다루어져 왔다. 이 가운데 대표성과 보편성을 가지는 곳으로 선정하여 연구를 수행한 결과 기존의 단순목적 보도공간을 4개의 공간 즉 보행자공간, 자전거도로공간, 차단 및 가로시설공간, 녹지 및 편익공간으로 재구성하였다. 이는 적은 비용과 노력으로 보행의 순기능인 쾌적성과 안전성을 보다 강화시켜나갈 수 있었다. 매연과 소음이 없고 도시민의 건강성를 확보한다는 이유로 여러 선진국에서는 수 년전부터 각광을 받고 있는 것이 보행교통과 자전거교통의 개념인 녹색교통이다. 이러한 녹색교통은 공해감소의 편익도 있지만 무엇보다 매력적인 도시환경의 창출과 인간중심적이라는 가치관에 그 의의가 있겠다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.291-298
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• 2017

In this paper, we derive the achievable degrees of freedom (DoF) for multiple-input multiple-output (MIMO) Z-interference channels (Z-IC) with reconfigurable antennas at the receivers, assuming that channel state information is not available at the transmitters. We propose a new linear scheme to align interfering signals and to decode desired signals through the designed preset mode switching pattern of reconfigurable antennas at the receivers. The key idea of our scheme is to use interfering signals as a side information at the interfered receiver by being silent at the corresponding transmitter during some time slots. Consequently, it is shown that the reconfigurable antennas at the receivers can bring a DoF gain if the number of preset modes is greater than the number of RF chains at the receivers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2099-2104
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• 2010

In this paper, HRV signal which was appeared RR intervals from ECG was analyzed using return-map during anesthesia. We intended to estimate the depth of anesthesia observing the change of autonomic nervous activity(ANS) because HRV showed change of cardio-vascular system of the body according to state of ANS. Return-map analysis is to reconstruct time series of HRV to phase space after calculating delay time and embedded time. After approximating the signal distribution which was reconstructed in phase space in elliptic, we calculated the lengths of major and minor axises of the elliptic and the values was used to estimate the depth of anesthesia. Stages of the anesthesia were 7 levels to evaluate the depth of anesthesia. At induction stage of strong external stimulation, the length of major and minor axis were statistically high and at the operation stage of non-external stimulation, the values were statistically low. Conclusively, the stages of anesthesia were discriminated by HRV signal mapped in the phase space during operation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.4
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• pp.353-362
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• 2012

3D building modeling from airborne Lidar without model regularization may cause positional errors or topological inconsistency in building models. Regularization of 3D building models, on the other hand, restricts the types of models which can be reconstructed. To resolve these issues, this paper modelled 3D buildings from airborne Lidar by building model regularization which considers more various types of buildings. Building points are first segmented into roof planes by clustering in feature space and segmentation in object space. Then, 3D building models are reconstructed by consecutive adjustment of planes, lines, and points to satisfy parallelism, symmetry, and consistency between model components. The experimental results demonstrated that the method could make more various types of 3d building models with regularity. The effects of regularization on the positional accuracies of models were also analyzed quantitatively.

• Journal of the Korea Society of Computer and Information
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• v.18 no.1
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• pp.185-192
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• 2013

The development of hardware, popularization of 3D graphics software could get to easily use 3d graphics tool in the school. And learning difficulties of a shape section increased through more being enforced a shape section of an elementary school. Thus we try to improve learning effectiveness in a shape section using Sketech Up software. To do this, we analyzed existing studies, classified 3D graphics software, provided the selection criteria of vector graphics software. And we explained how to select 3D graphics software. We selected and reorganized the shape contents to use Sketch Up, which make and rotate 3D figures, understand aspects of a shape. And we inserted the content about piling 3D figures in the beginning state of the curriculum. we composed 10 periods and practiced our reorganized curriculum to the teaching and learning using Sketch Up. And we conducted before & after survey to check out t-verified. And we acquired meaningful results statistically. Thus applying Sketch Up to the shape learning can be analyzed effectively.

• Korean Institute of Interior Design Journal
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• v.19 no.6
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• pp.241-248
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• 2010

The population of the elderly is rapidly increased because maturation of the social welfare system and development of medical technology. However, welfare environments for the elderly are poor either in its quality or its quantity. The aims of this study is to confirm the space improvement possibility to change the Gyung Ro Dang to the senior life support center as a community welfare service network. This study is done by the comparative analysis between existing Gyung Ro Dang in korea and former cases in Japan based on the elderly's facility preference. The facility's space reprogramming alternative from that analysis is applied to change the Gyung Ro Dang to a network facility for the regional senior life support. Afterward, it is proposed that first, facilities should be expanded scale by the new education and health improvement facilities functional room that the modern elderly need. second, Facility space will be reconstitution because the Gyung Ro Dang have to be extended it's role as a community welfare network.

• 한국공간정보시스템학회:학술대회논문집
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• 2003.11a
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• pp.147-152
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• 2003

TPR-tree는 이동체의 위치 데이터에 대해 현재 및 미래 위치 질의를 지원하기 위하여 시간 함수 기반의 경계사각형(Sounding Rectangle)으로 이동체를 색인한다. 경계사각형의 각 축은 가장 빠른 속도로 이동하는 이동체의 속도 값을 이용하여 시간에 따라 확장한다. 경계사각형 영역의 확장으로 중복(overlap)이 심화되고 사장영역(dead space)이 커지는 문제가 있다. 따라서 시간이 지날수록 영역질의 시 성능이 떨어진다. 이 논문에서는 시간이 지남에 따라 발생하는 노드간의 심한 중복과 사장영역을 줄이기 위해 중복이 심한 두 개의 단말노드를 강제 합병하고 재분할하는 강제 합병 정책과 이동체의 삭제가 발생한 노드의 모든 이동체들을 강제적으로 재삽입하는 삭제노드 강제 재삽입 정책과 삭제가 발생한 노드와 중복되는 노드들의 이동체들을 강제적으로 재삽입하는 중복 노드 강제 재삽입 정책을 이용한다. 강제 합병 정책과 삭제 노드 강제 재삽입 정책, 그리고 중복 노드 강제 재삽입은 TPR-tree의 구조를 점진적으로 재구성하기 때문에 이동체의 현재 분포를 고려하여 색인 구조를 동적으로 개선하는 장점을 가진다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.641-644
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• 2001

기존의 종이지도를 수치지도 처리과정으로 얻어진 등고선(contour line) 데이터는 원격탐사(Remote Sensing)와 지리정보시스템(GIS)의 응용분야에서 주로 사용되어지는 데이터이다. 이러한 등고선은 해당 지역의 DTM(Digital Terrain Model) 데이터 생성을 위해 보간(interpolation)하여 생성하는 데 연구가 집중되어 왔다. 본 논문에서는 DEM(Digital Elevation Model)으로부터 얻어진 등고선 데이터를 이용하여 사용자에게 3 차원으로 가시화 해 줄 수 있는 기법을 소개한다. 등고선 추출을 위한 방법으로는 기존의 소개되어진 Marching Square 알고리즘을 적용하였고, 지역적인 최고점(local minimum)과 최소점(maximum)을 구하기 위해 등고선을 열린 등고선(open contour)과 닫힌 등고선(closed contour)으로 분류하게 된다. 지역적 최고, 최소점을 찾기 위한 탐색공간을 줄이기 위해 닫힌 등고선만을 대상으로 등고선 트리를 생성하였으며, 생성된 트리의 리프노드에 대해서 최고, 최소점에 대한 근사(approximation)를 수행하게 된다. 이렇게 구해진 근사된 정점들과 등고선 데이터를 입력으로 하여 제한된 딜로니 삼각분할(Constrained Delaunay Triangulation)을 수행함으로써, 3 차원 지형을 재구성할 수 있다. 실험에서 USGS 로부터 획득한 지형 데이터를 이용하여 속도 측정을 하였다. 결과적으로 저장공간 측면에서 적은 량의 데이터를 가지면서 등고선을 표현할 수 있는 3 차원 지형을 렌더링 할 수 있음을 알 수 있다.

• Progress in Medical Physics
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• v.26 no.1
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• pp.28-35
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• 2015

In this study, we investigated the effects of an iterative reconstruction algorithm and an automatic exposure control (AEC) technique on image quality and radiation dose through phantom experiments with coronary computed tomography (CT) angiography protocols. We scanned the AAPM CT performance phantom using 320 multi-detector-row CT. At the tube voltages of 80, 100, and 120 kVp, the scanning was repeated with two settings of the AEC technique, i.e., with the target standard deviations (SD) values of 33 (the higher tube current) and 44 (the lower tube current). The scanned projection data were reconstructed also in two ways, with the filtered back projection (FBP) and with the iterative reconstruction technique (AIDR-3D). The image quality was evaluated quantitatively with the noise standard deviation, modulation transfer function, and the contrast to noise ratio (CNR). More specifically, we analyzed the influences of selection of a tube voltage and a reconstruction algorithm on tube current modulation and consequently on radiation dose. Reduction of image noise by the iterative reconstruction algorithm compared with the FBP was revealed eminently, especially with the lower tube current protocols, i.e., it was decreased by 46% and 38%, when the AEC was established with the lower dose (the target SD=44) and the higher dose (the target SD=33), respectively. As a side effect of iterative reconstruction, the spatial resolution was decreased by a degree that could not mar the remarkable gains in terms of noise reduction. Consequently, if coronary CT angiogprahy is scanned and reconstructed using both the automatic exposure control and iterative reconstruction techniques, it is anticipated that, in comparison with a conventional acquisition method, image noise can be reduced significantly with slight decrease in spatial resolution, implying clinical advantages of radiation dose reduction, still being faithful to the ALARA principle.