• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.31-33
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• 2001

고비용의 공간 연산을 수행해야 하는 공간 질의 처리는 여과-정제의 2단계 처리가 일반적이다. 그러나, 2단계 색인 방법은 여과율이 좋지 못한 단점이 있으므로, 최근 다단계 여과 과정이 많이 연구되고 있다. 다단계 여과 과정은 1차 여과된 객체에 대하여 더욱 정밀한 필터를 적용함으로써 후부 객체 수를 줄이는 방법으로 접근하고 있으나, 여러 번의 여과 단계를 거치므로 수행 시간이 길어지고 추가 정보유지로 인한 저장 공간 낭비 등의 단점이 있다. 본 논문에서는 전체 공간 영역을 격자로 분할하고, 객체를 격자 위에 구성하는 2단계의 공간 색인 방법을 제안한다. 제안된 색인 방법은 Dead Space의 크기를 줄이고, 한 번의 여과 과정으로 높은 여과율을 갖는다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8A
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• pp.784-789
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• 2006

In this paper, we propose a bitwise information decomposition algorithm for an M-PSK signal based on the Max-Log-MAP algorithm. In order to obtain the algorithm, we use a coordinate transformation from M-PSK to M-PAM signal space. Using the proposed algorithm, we analyze the performance of a Turbo iterative decoding method. The proposed algorithm can be applicable not only for a communication with PSK and iterative decoding method but for adaptive modulation and coding system.

• The KIPS Transactions:PartD
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• v.9D no.2
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• pp.203-214
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• 2002

This paper presents a physical database design methodology for spatial access structures using transformation techniques in spatial database systems. Recently, many spatial access structures have been proposed in the literature. However, there has been no effort for their physical database design. We first show that most spatial queries in the original space are transformed into one type of range queries in the transform space, and then propose a method for finding the optimal configuration of spatial access structures by using the relationship between the shapes of query regions, that are correspond to the range queries, and page regions, that are correspond to data pages, in the transform space. For performance evaluation, we perform extensive experiments with the MBR-MLGF, a spatial access structure using transformation techniques, using various types of queries and data distributions. The results indicate that our proposed method builds optimal MBR-MLGF according to the query types. When the interval ratio of a transformed four-dimensional query region is 1 : 16 : 256 : 4096, the performance of the proposed method is enhanced by as much as five times over that of the conventional cyclic splitting method. The result confirms that the proposed physical database design methodology is useful in a practical way.

• Journal of Korea Spatial Information System Society
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• v.7 no.3 s.15
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• pp.119-130
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• 2005

A spatial data warehouse is a system that stores geographical information as a subject oriented, integrated, time-variant, non-volatile collection for efficiently supporting decision. This system consists of a builder and a spatial data warehouse server. A spatial data warehouse server suspends user services, stores transferred data in the data repository and constructs index using stored data for short response time. Existing methods that construct index are bulk-insertion and index transfer methods. The Bulk-insertion method has high clustering cost for constructing index and searching cost. The Index transfer method has improper for the index reconstruction method of a spatial data warehouse where periodic source data are inserted. In this paper, the efficient index reconstruction method using a partial index in a spatial data warehouse is proposed. This method is an efficient reconstruction method that transfers a partial index and stores a partial index with expecting physical location. This method clusters a spatial data making it suitable to construct index and change treated clusters to a partial index and transfers pages that store a partial index. A spatial data warehouse server reserves sequent physical space of a disk and stores a partial index in the reserved space. Through inserting a partial index into constructed index in a spatial data warehouse server, searching, splitting, remodifing costs are reduced to the minimum.

• Journal of Korea Game Society
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• v.12 no.2
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• pp.53-62
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• 2012

Visualizing a volume dataset with ray-casting which of visualization methods provides high quality image. However it spends too much time for rendering because the size of volume data are huge. Recently, various researches have been proposed to accelerate GPU-based volume rendering to solve these problems. In this paper, we propose an efficient GPU-based empty space skipping to accelerate volume ray-casting using octree traversal. This method creates min-max octree and searches empty space using vertex splitting. It minimizes the bounding polyhedron by eliminating empty space found in the octree traveral step. The rendering results of our method are identical to those of previous GPU-based volume ray-casting, with the advantage of faster run-time because of using minimized bounding polyhedron.

• Korean Journal of Remote Sensing
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• v.19 no.4
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• pp.329-339
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• 2003

In this study, an approach of image fusion in decision level has been proposed for unsupervised image classification using the images acquired from multiple sensors with different characteristics. The proposed method applies separately for each sensor the unsupervised image classification scheme based on spatial region growing segmentation, which makes use of hierarchical clustering, and computes iteratively the maximum likelihood estimates of fuzzy class vectors for the segmented regions by EM(expected maximization) algorithm. The fuzzy class vector is considered as an indicator vector whose elements represent the probabilities that the region belongs to the classes existed. Then, it combines the classification results of each sensor using the fuzzy class vectors. This approach does not require such a high precision in spatial coregistration between the images of different sensors as the image fusion scheme of pixel level does. In this study, the proposed method has been applied to multispectral SPOT and AIRSAR data observed over north-eastern area of Jeollabuk-do, and the experimental results show that it provides more correct information for the classification than the scheme using an augmented vector technique, which is the most conventional approach of image fusion in pixel level.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.442-444
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• 2016

과거에 비해 비약적으로 생산되는 공간 데이터에 대한 처리를 위한 공간 연산은 빠른 처리 응답성을 요구하는 경우가 많다. 그래서 최근 하둡(Hadoop)과 같은 빅데이터 처리 시스템을 이용하여 처리하고자 하는 시도가 많다. 한편, 공간 조인은 데이터 분할(Partitioning)과 공간 색인의 이용 여부, 여과 단계와 정제 단계를 거치는 등 그 복잡도가 강한 공간 연산이다. 그래서 빅데이터 처리 시스템을 이용한 공간 조인의 처리 방식은 매우 다양하다. 그러나 지금까지 이러한 공간 조인의 처리 방식에 다른 리소스 활용에 대한 비교는 거의 없다. 이 논문에서는 다양한 공간 연산의 수행 방법에 따른 빅데이터 시스템 클러스터에서 데이터 전송 방식을 고찰하고 데이터 전송에 따른 네트워크 리소스의 효율적인 사용 방안을 제안하고자 한다. 구체적으로 단일할당과 다중할당 색인 기법의 비교, 파티셔닝 방법의 비교, 맵리듀스 시스템의 태스크 할당 방법에 따른 비교를 통해 다양한 연산 유형에 따른 공간 조인의 처리 방안 선정에 고려 요소를 제시하고자 한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05c
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• pp.272-276
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• 2002

본 논문은 영역을 병합할 때 두 영역의 색상 차를 영역 병합의 제한 조건으로 사용하는 칼라 영상 분할 기법을 제안하였다. 이는 먼저 영역의 경계선 정보를 잘 보존하기 위해서 RGB 공간상에서 수리형태학 필터와 변형된 워터쉐드 알고리즘을 이용하여 칼라 영상을 과분할 한다. 그리고 영역 간의 색상 차를 제한 조건으로 사용하는 영역 병합 과정을 반복 수행하여 칼라 영상의 분할 결과를 얻는다. 이는 인간 시각 시스템이 색상, 채도, 명도의 형태로 색을 구분하는 것을 기반으로 한다. 명도가 낮지 않는 경우에 색차 보다 색상 차가 중요한 요소로 작용하기 때문에 이를 영역 병합의 제한 조건으로 사용한다. 실험결과에서 제안된 칼라 영상 분할 기법은 다양한 칼라 영상에 대하여 적은 개수의 영역으로 동일한 색상을 가지는 영역의 경계선을 유지하는 효율적인 분할을 보임을 확인하였다.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.5
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• pp.13-21
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• 2020

This paper proposes a sign reversal channel switching method in space-frequency block code for orthogonal frequency division multiplexing system. In case of sending source data on other antenna, it is necessary for the receiver to change combining method according to the channel variation. If one does not know the predefined channel switching sequence, it is not possible to decode the received data precisely. In transmit data symbols' exchanges for a channel switching, data symbols are exchanged according to a format of space-frequency block code. In this paper, we proposes a simple sign reversal method except exchanging data symbols between transmit antennas. It is shown that this method occurs another combining method for a simple encryption in the receiver.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.157-162
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• 2018

Tracking the location of patients in medical facilities is important to guarantee the patients' safety and to improve the service quality. Previous studies related to location tracking systems based on Bluetooth communication need numerous prerequisite information and multiple devices to improve the accuracy. In this paper, we propose a beacon-based space partition scheme that assigns different arrangement patterns of beacons to different spaces and composes groups with the similar value of RSSI to minimize prerequisite information and the number of beacons. The proposed scheme considers a pattern arrangement scheme to minimize intereference between neighbor patterns. We also verified the applicability of our scheme to monitor the patient location by using experimental results.