• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.207-213
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• 2006

In this paper, we reduce the computational complexity to find the minimum distance of RA codes by searching only valid codewords using repetition part. Since LDPC codes have repetition part like RA codes, we also apply this algorithm for computing the minimum distance of LDPC codes. The minimum distance dominates the code performance at high signal-to-noise ratios(SNRs) and in turn allows an estimate of the error floor. The proposed algorithm computes the minimum distance without any constraint on code structures. The minimum distances of LDPC codes and RA codes with large interleavers of practical importance are computed and used to obtain the error floor, which is compared with the performance of the iterative decoding.

• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.52-59
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• 2011

In this paper, we propose an indexing method to support efficient similarity search for sequence databases. We present a new distance measurement called minimum DTW distance to enhance the filtering effects. The minimum DTW distance is to measure the minimum distance between a sequence data and the group of similar sequences. It enables similarity search through hierarchical index structure by filtering sequence databases. Finally, we show the superiority of our method through some experiments.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.4
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• pp.169-180
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• 2019

Shorelines should be extracted with consistency because they are the reference for determining the shape of a country. Even in the same area, inconsistent minimum vertex intervals cause inconsistencies in the coastline length, making it difficult to acquire reliable primary data for national policy decisions. As the shoreline length cannot be calculated consistently for shorelines produced by determining the arbitrary distance between points below 1m, a methodology to calculate consistent shoreline length using the minimum vertex interval is proposed herein. To compare our results with the shoreline length published by KHOA(Korea Hydrographic and Oceanographic Agency) and analyze the change in shoreline length according to the minimum vertex interval, target sites was selected and the grid overlap of the shoreline was determined. Based on the comparison results, minimum grid sizes and the minimum vertex interval can be determined by deriving a polynomial function that estimates minimum grid sizes for determining consistent shoreline lengths. By comparing public shoreline lengths with generalized shoreline lengths using various grid sizes and by analyzing the characteristics of the shoreline according to vertex intervals, the minimum vertex intervals required to achieve consistent shoreline lengths could be estimated. We suggest that the minimum vertex interval methodology by quantitative evaluation of the determined grid size may be useful in calculating consistent shoreline lengths. The proposed method by minimum vertex interval determination can help derive consistent shoreline lengths and increase the reliability of national shorelines.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.114-116
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• 2011

해상교통 관제 서비스는 해상교통량의 폭주, 위험화물의 증가와 잠재적인 환경오염의 위험 등에서 항만의 안전 또는 항만운영 효율성 제고하기 위해 실시하는 통항서비스로 VTS 구역 내에서 주변상황 및 해상교통상황을 적시에 제공하여 선박에서 항해의사 결정과정에 도움이 될 수 있도록 정보서비스 등을 제공하고 있으며 실제로 안전한 해상교통에 많은 도움을 주고 있는 것이 사실이다. 우리나라 전 연안 및 항만에서 운영하고 14개소의 VTS 및 연안 VTS 서비스를 제공하고 있다. VTS 관제사는 선박운항자와 마찬가지로 관제하고 있는 항만이나 연안의 지형적 특성에 따라 선박의 안전한 운항을 위해 선박과 선박 사이 및 선박과 육지(장해물)와의 최소안전거리를 두고 관제를 하고 있다. 본 연구에서는 우리나라 각 VTS 관제사들이 관제하는 안전이격거리를 개인별로 조사함으로써 VTS 관제사간의 안전이격거리를 조사함에 그 목적이 있다. 설문조사 결과 같은 VTS 소속임에도 불구하고 개인별로 관제하는 최소안전거리가 많은 차이가 있음을 확인할 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10C
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• pp.1363-1369
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• 2004

LDPC(Low Density Parity Check) codes are described by bipartite graphs with bit nodes and parity-check nodes. Tanner derived minimum distance bounds of the regular LDPC code in terms of the eigenvalues of the associated adjacency matrix. In this paper we generalize the Tanner's results. We derive minimum distance bounds applicable to both regular and blockwise-irregular LDPC codes. The first bound considers the relation between bit nodes in a minimum-weight codeword, and the second one considers the connectivity between parity nodes adjacent to a minimum-weight codeword. The derived bounds make it possible to describe the distance property of the code in terms of the eigenvalues of the associated matrix.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.10
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• pp.11-15
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• 2015

In this paper, we introduce three modulation codes of the code rate 1/2 with different minimum distances, respectively, and investigate the performance of the codes according to the minimum distance. We simulate the codes in accordance with blur and misalignment. As the minimum distance increases, the complexity of encoder and decoder also grows. However, it can improve the error correcting capability and shows good performance with blur and misalignment.

• The Transactions of the Korea Information Processing Society
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• v.3 no.7
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• pp.1707-1718
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• 1996

Given a signal net N=s, 1,...,n to be the set of nodes, with s the source and the remaining nodes sinks, an MRDPT (minimum-cost rectilinear Steiner distance -preserving tree) has the property that the length of every source to sink path is equal to the rectilinear distance between the source and sink. The minimum- cost rectilinear Steiner distance-preserving tree minimizes the total wore length while maintaining minimal source to sink length. Recently, some heuristic algorithms have been proposed for the problem offending the MRDPT. In this paper, we investigate an optimal structure on the MRDPT and present a theoretical breakthrough which shows that the min-cost flow formulation leads to an efficient O(n2logm)2) time algorithm. A more practical extension is also in vestigated along with interesting open problems.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.5-10
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• 2005

T.S. HANBADA will navigate to maintain the adequate distance between own ship and other ships safely for about 17 hours on the about 2 kts. On the above situation, M broadcasting station requires to maintain the distance from 100m to 500m between ships. This paper aims to calculate the minimum safe distance between ships, the distance is assessed by using ES Model which is a quantitative model for evaluating the difficulty of shiphandling. After marine traffic flow simulation, minimum safe distance for HANBADA on the 2kts is about 260m based ES value. On this paper, the result was compared about its distance to the actual navigating distance.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.32-41
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• 1999

In spatial database system, the nearest neighbor query occurs frequently and requires the processing cost higher than other spatial queries do. The number of nodes to be searched in the index can be minimized for optimizing the cost of processing the nearest neighbor query. The optimal search distance is pr9posed for the measurement of a search distance to accurately select the nodes which will be searched in the nearest neighbor query. In this paper, we prove properties of the optimal search distance in N-dimensional. We show through experiments that the performance of query processing of our method is superior to other method using maximum search distance.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.353-356
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• 2007

chamfer 정합(matching)은 많은 응용분야에서 사용되온 에지(edge) 기반 정합기법으로, 변환된 모델에지와 영상에지간의 거리를 최소화하는 과정이다. 이 거리는 보통 거리변환을 이용하여 픽셀분해능으로 계산된다. 본 논문에서는 서브픽셀(subpixel) 거리계산을 위해 거리계산시 보간법을 사용하여, 정확한 chamfer 정합을 구현한, 개선된 chamfer 정합 방법을 제안한다. 또한, 보다 정밀한 정합을 위해, 최소거리를 갖는 픽셀위치의 주변영역을 이용하여 최적의 위치를 추정하지 않고, 서브픽셀로 실제 거리계산을 통해 최소 거리를 찾기 위해 Powell 의 최적화기법을 이용하였다. 실험결과는 제안된 방법의 타당성을 보여주었다.