• Electronics and Telecommunications Trends
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• v.37 no.6
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• pp.43-53
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• 2022

Message Passing Interface (MPI) collective communication has been applied to various science and engineering area such as physics, chemistry, biology, and astronomy. The parallel computing performance of the data-intensive workload in the above research fields depends on the collective communication performance. To overcome this limitation, MPI collective communication technology has been extensively researched over the last several decades to improve communication performance. In this paper, we provide a comprehensive survey of the state-of-the-art research performed on the MPI collective communication and examine the trends of recently developed technologies. We also discuss future research directions for providing high performance and scalability to large-scale MPI applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.541-548
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• 2005

IP lookup and forwarding process becomes the bottleneck of packet transmission as IP traffic increases. Previous hardware-based IP address lookup schemes using an index-based table are not memory-efficient due to sparse distribution of the routing prefixes. In this paper, we propose memory-efficient hardware based IP lookup scheme called set-associative IP address lookup scheme, which provides the same IP lookup speed with much smaller memory requirement. In the proposed scheme, an NHA entry stores the prefix and next hop together. The IP lookup procedure compares a destination IP address with eight entries in a corresponding set simultaneously and finds the longest matched prefix. The memory requirement of the proposed scheme is about $42\%$ of that of Lin's scheme. Thus, the set-associative IP address lookup scheme is a memory-efficient hardware based IP address lookup scheme.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.12
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• pp.1345-1354
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• 2015

This paper, information communication code standard($KS{\times}1001$, confirmation in 2004), as definded in Hangul Character Code Hangul AMI/HDB-3 the code set for the new system Hangul consonant and vowel tables presented. The result of the existing system and the code set ($4{\times}4$) bit source coding rules for comparing the frequency of use Hangul consonant and vowel tables(The National Institute of The Korea Language) and statistices showed that 44% of the data processing efficiency is improved.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.1
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• pp.1-6
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• 2014

Most of the previous algorithms focus on computing the convex hull for a set of points. In this paper, we present a method for approximating the convex hull for a set of spheres with various radii in discrete space. Computing the convex hull for a set of spheres is a base technology for many applications that study structural properties of molecules. We present a voxel map data structures, where the molecule is represented as a set of spheres, and corresponding algorithms. Based on CUDA programming for using the parallel architecture of GPU, our algorithm takes less than 40ms for computing the convex hull of 6,400 spheres in average.

• Journal of KIISE:Information Networking
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• v.28 no.1
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• pp.71-81
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• 2001

최근 병렬처리 시스템에 대한 연구는 마이크로 프로세서 제작 기술과 네트워크 기술이 발달함에 따라 고성능의 PC와 워크스테이션 여러대를 고속의 네트워크로 연결하여 구축하는 클러스터링 환경에 관심이 고조되고 있다. 그런데 이러한 클러스터링 시스템의 성능은 수행되는 애플리케이션 프로그램의 병렬성이나 xdhtls 빈도 등의 특성에 따라 달라진다. 그러므로 클러스터링 시스템의 성능을 향상시키기 위해서는 애플리케이션의 이러한 특성을 고려하여 최상의 효과를 얻기 위한 조정작업이 필요하며 그 방법중의 하나가 시스템 상에서 발생하는 통신들에 대하 스케줄링을 수행하는 것이다. 본 논문에서는 Myrinet 스위치를 사용하여 선형으로 구성한 클러스터링 시스테과 2차원 메쉬 형태로 구성한 클러스터링 시스템의 두 가지 모델을 가정하고 이들 모델 상에서 특성 시간에 주어지는 통신요청들에 대하여 순위차원 라우팅을 사용하여 메시지들을 최단시간에 전송할 수 있는 최적 통신스케줄링 알고리즘을 제안한다. 시스템 상에서 같은 방향으로 동시에 링크를 공유한는 통신들의 개수의 최대값을 $L_{MAX}$로 시스템에서 하나의 메시지가 전달되는데 걸리는 시간을 T로 정의하면 알고리즘에 의해 선형 네트워크에서의 통신 요청 집합에 대한 메시지 전송 완료 시간은 최대 $L_{MAX}{\cdot}T$, 메쉬 네트워크에서의 통신요청 집합에 대한 메시지 전송 완료시간은 최대 $frac{3}{2}{\cdot}T$임을 증명하였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.905-915
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• 2012

This paper suggests the online method to identify normal and abnormal state of water quality on the ocean USN. To define normal of the ocean water quality, we utilize the negative selection algorithm of artificial immunity system which has self and nonself identification characteristics. To distinguish abnormal status, normal state set of the ocean water quality needs to be defined. For this purpose, we generate normal state set base on mutations of each data and mutation of the data as logical product. This mutated normal (or self) sets used to identify abnormal status of the water quality. We represent the experimental result about mutated self set with the Gaussian function. Through setting the method on the ocean sensor logger, we can monitor whether the ocean water quality is normal or abnormal state by online.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.906-911
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• 2005

In this paper, for spatial multiplexing with limited feedback, we propose subspace method based preceding in which the active bases are selected at the receiver from a finite number of basis sets Down at both receiving and transmitting ends, conveyed to the transmitter using limited feedback, and assembled into a preceding matrix at the transmitter. The selected bases are conveyed to the transmitter using feedback information on both the index of the selected basis set, which defines the most appropriate set of coordinates for describing a multiple-input multiple-output (MIMO) channel, and the principal bases maximizing the capacity in the selected basis set. We show that the proposed subspace method based preceding provides a capacity similar to that of the closed-loop MIMO even with limited feedback.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1161-1166
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• 2005

In this paper, for spatial multiplexing with limited feedback, we propose subspace based precoding in which the active bases are selected at the receiver from a finite number of basis sets known at both receiving and transmitting ends, conveyed to the transmitter using limited feedback, and assembled into a preceding matrix at the transmitter. The selected bases are conveyed to the transmitter using feedback information on both the index of a basis set, which indicates the most appropriate set of coordinates for describing a MIMO channel, and the active bases having the significant amounts of energy in the selected basis set. We show that the proposed subspace based precoding provides capacity similar to that of the closed-loop MIMO even with limited feedback.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2812-2817
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• 2013

In this paper, an outage probability for the best relay selection in decode-and-forward relaying systems in the presence of interference is analyzed over Rayleigh fading channels. Based on the outage performance results, we propose a method to determine effective relay candidates for the best relay selection, where the effective relay candidates represent the relays except for relays that make no contribution to improving the performance. in all possible relays given in the system. By determining the effective relay candidates, the feedback overhead of channel state information and the energy consumption of relays can be significantly reduced while minimizing the performance degradation. In this paper, we provide important parameters that affect the determination of the effective relay candidates.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1023-1030
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• 2020

We address the sampling set selection problem for arbitrary graph signals such that the original graph signal is reconstructed from the signal values on the nodes in the sampling set. We introduce a variation difference as a new indirect metric that measures the error of signal variations caused by sampling process without resorting to the eigen-decomposition which requires a huge computational cost. Instead of directly minimizing the reconstruction error, we propose a simple and fast greedy selection algorithm that minimizes the variation differences at each iteration and justify the proposed reasoning by showing that the principle used in the proposed process is similar to that in the previous novel technique. We run experiments to show that the proposed method yields a competitive reconstruction performance with a substantially reduced complexity for various graphs as compared with the previous selection methods.