• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.597-600
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• 2004

A substantial number of processes have been suggested as possible contributors to the extragalactic $\gamma$-ray background (EGRB). Yet another contribution to this background will be emission produced in hadronic interactions of cosmic-ray protons with the cluster thermal gas; this class of cosmic rays (CRs) has been shown to be responsible for the EUV emission in the Coma Cluster of galaxies. In this paper we assume the CRs in the Coma Cluster is prototypic of all clusters and derive the contribution to the EGRB from all clusters over time. We examine two different possibilities for the scaling of the CR flux with cluster size: the number density of the CRs scale with the number density of the thermal plasma, and alternatively, the energy density of the CRs scale with the energy density of the plasma. We find that in all scenarios the EGRB produced by this process is sufficiently low that it will not be observable in comparison with other mechanisms that are likely to produce an EGRB.

• Journal of the Korean Society for information Management
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• v.21 no.4 s.54
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• pp.173-185
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• 2004

Fast and high-quality document clustering algorithms play an important role in providing data exploration by organizing large amounts of information into a small number of meaningful clusters. Many papers have shown that the hierarchical clustering method takes good-performance, but is limited because of its quadratic time complexity. In contrast, with a large number of variables, K-means has a time complexity that is linear in the number of documents, but is thought to produce inferior clusters. In this paper, Condor system using K-Means algorithm Compares with regular method that the initial centroids have been established in advance, our method performance has been improved a lot.

• The Journal of the Acoustical Society of Korea
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• v.26 no.5
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• pp.199-206
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• 2007

In this paper we propose a new clustering algorithm that performs clustering the feature vectors for the speaker identification. Unlike typical clustering approaches, the proposed method performs the clustering without the initial guesses of locations of the cluster centers and a priori information about the number of clusters. Cluster centers are obtained incrementally by adding one cluster center at a time through the boundary subtractive clustering algorithm. The number of clusters is obtained from investigating the mutual relationship between clusters. The experimental results for artificial datum and TIMIT DB show the effectiveness of the proposed algorithm as compared with the conventional methods.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.64.1-64.1
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• 2016

We study the evolution of a late-type galaxy (LTG) in a rich cluster environment by using N-body/SPH simulations. To do that we perform a set of simulations of a LTG falling in a Coma-like cluster and also the LTG colliding with early-type galaxies (ETGs) multiple times in the cluster environment. We use a catalog of the Coma cluster in order to estimate the typical number of collisions and the closest approach distances that a LTG would experience in the cluster. We investigate the cold gas depletion and star formation quenching of our LTG model influenced by the hot cluster gas as well as the hot halo gas of the colliding ETGs.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1E
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• pp.29-33
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• 1996

A categorization for cluster is necessary when an unsupervised classfication is used for remote sensing image classification. It is desirable that this method is performed automatically, because manual categorization is a highly time consuming process. In this paper, several automatic determination methods were proposed and evaluated. They are four methods. a) maximum number method : which assigns the tharget cluster to the category which occupies the largest area of that cluster b) maximum percentage method : which assigns the target cluster to the category which shows the maximum percentage within the category in that cluster. c) minmun distance method : which assigns the target cluster to the category having minmum distance with that cluster d) element ratio matching method : which assigns local regions to the category having the most similar element ratio of that region From the results of the experiments, it was certified that the result of minimum distance method was almost the same as the result made by a human operator.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.06a
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• pp.67-71
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• 2003

In order to manage a cluster system that consists of a number servers, management aspects such as configuration management, fault management, performance management, and user management should be considered. Especially, it is necessary to monitor performances for performance and fault management. An agent in each server collects performance counters, status changes, and events occurred in normal or abnormal states. The data collected are delivered to a collector sorter and processed in a report tool for performance analysts and management decision in the cluster system point of view, by detecting fault state and tracing out resource usage, service response, and response, and states until failed. In this paper we propose an architecture modeling of a performance report tool for proactive cluster system management. Some results on a cluster system are presented.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.1
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• pp.35-41
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• 2017

This paper presents the development of a monitoring and control system for a vehicle cluster using a model-based design technique. For MBD(model-based design), MATLAB GUI(Graphic User Interface), M programs, simulink, state flow, and tool boxes are used to monitor a number of data such as warning, interrupts, and etc. connected to a real vehicle cluster. As a monitoring tool, a PC(Personal Computer) station interworks with the real vehicle cluster through the interface commands of tool boxes. Thus, unlike existing text-based designs, the MBD based vehicle cluster system provides very easy algorithm updates and addition, since it offers a number of blocks and state flow programs for each functional actions. Furthermore, the proposed MBD technique reduces the required time and cost for the development and modification of a vehicle cluster, because of verification and validation of the cluster algorithm on the monitor through a PC.

• Journal of Environmental Science International
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• v.17 no.5
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• pp.517-524
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• 2008

The purpose of this study was to investigate the characteristics of air quality using data from which obtain local air quality monitoring system for cohort study in Chungju, Korea. We analyzed the concentration data of $NO_2,\;SO_2$, and $PM_{10}$ in Chungju and industrial cities in 2006. We compared a industrial area with a cohort study area using by bicluster algorithm. In the case of $SO_2$, the rate of the cluster time was $10{\sim}60%$ and the cluster time number of two areas was similar. In the case of $NO_2$ and $PM_{10}$, the number of cluster time between a industrial area and cohort study area was clearly different.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.880-887
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• 2011

The Wireless Mesh Network(WMN) technology is able to provide an infrastructure for isolated islands, in which it is difficult to install cables or wide area such as battlefield. Therefore, WMN is frequently used to satisfy needs for internet connection and active studies and research on them are in progress. However, as a result of increase in number of hops under hop-by-hop communication environment has caused a significant decrease in throughput and an increase in delay. Considering the heavy traffic of real-time data, such as voice or moving pictures to adaptive WMN, in a military environment. Such phenomenon might cause an issue in fairness index. In order to resolve this issue, we proposed a Cluster Based Multi-channel Assignment Scheme(CB-MAS) for adaptive tactical wireless mesh network. In the CB-MAS, the communication between the Cluster-Head(CH) and cluster number nodes uses a channel has no effect on channels being used by the inter-CH links. Therefore, the CB-MAS can minimize the interference within multi-channel environments. Our Simulation results showed that CB-MAS achieves improved the throughput and fairness index in WMN.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.569-575
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• 2007

The main issue of this study is to find ways to lengthen the lifetime of network mainly by reducing energy consumption. This paper proposes how to reduce the amount of data transmitted in each sensor and cluster head in order to lengthen the lifetime of sensor network. The most important factor of reducing the sensor's energy dissipation is to reduce the amount of messages transmitted. This study proposes cluster cohesion for the purposes. The method is to use the cluster cohesion and manage the number of clusters adaptively and reduce the amount of message transmitted in network topology. This method should be much more efficient and effective as it reduces the network traffic significantly and increases the network's lifetime.