• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.1954-1971
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• 2017

In this work, first, a multiuser detection (MUD) algorithm based on component-level soft interference cancellation and linear minimum mean square error (CLSIC-LMMSE) is proposed, which can enhance the bit error ratio (BER) performance of the traditional SIC-LMMSE-based MUD by mitigating error propagation. Second, for non-binary low density parity check (NB-LDPC) coded high-order modulation systems, when the proposed algorithm is integrated with partial mapping, the receiver with iterative detection and decoding (IDD) achieves not only better BER performance but also significantly computational complexity reduction over the traditional SIC-LMMSE-based IDD scheme. Extrinsic information transfer chart (EXIT) analysis and numerical simulations are both used to support the conclusions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.1077-1088
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• 1996

In this paper, we propose a new method to analyze the performance degradation by timing jitters in the receivers of intensity modulation/direct detection digital optical communication systems where pulse-shaping filters are used to minimize intersymbol interference. The results obtained from the proposed analytical method show that conventional analytical methods underestimate the influence of timing jitters on the receiver performance. Using the proposed anlaytical method, we derive an analytic equation for approximated power penalty due to timing itters and obtain an exact power penalty by numerical analyses. Assuming Gaussian or uniform probability density function for timing jitters, we also show that assumption of Gaussian distribution for timing jitters yields more performance degration than that of uniform distribution.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.1-5
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• 2018

The property of magnetic field and properties of EMW(Electro Magnetic Wave) absorption with multi-shaped EMW absorber was simulated. As a magnetic field having high density was showed at bottom of EMW absorber, simulation showed that overall EMW was absorbed at the bottom of multi-shaped absorber. The absorption properties of EMW according to thickness of absorber showed that it enhanced about 50-60 percent. Also, EMW absorption properties was checked with surface area of EMW absorber. A cylinder-shaped EMW absorber exhibited good property among multi-shaped EMW absorber based on these result.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.2
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• pp.317-325
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• 2012

In this paper, we consider the encoding scheme of Low Density Parity Check codes. In particular, using the Jacket Pattern and circulant permutation matrices, we propose the simple encoding scheme of Richardson's lower triangular matrix. These encoding scheme can be extended to a flexible code rate. Based on the simple matrix process, also we can design low complex and simple encoders for the flexible code rates.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.3
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• pp.130-134
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• 1982

In computer communication network, it is assumed that blocks are served at a rate of u messages per sec. The message blocks will be stayed in the buffer during the service time. In this case, the probability density distribution of the number of message blocks in the buffer space has been studied. When the average buffer space needed is minimum, the average block size will be specified by the relation between the input data and link infromation length. This relation proves to be perfect. The random number generator for this probability distribution is designed. The test result by making use of the random number generator has shown that is has little difference from the theoretical one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.5
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• pp.468-574
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• 1991

In construction of breadth-frist tree, the communication complexity can be reduced by efficent synchronization schemes based on several threshold values, We determine several new threshold values by considering the graph density represented as lognm, where n and m are the number of nodes and links., repectively. When thesethreshold values are used in the synchroization method for constructing distrbuted bradth-first search tree, we can obtain a more efficient algorithm in sparse graphs, and also, this algorithm has vthe same performance for communication complexity in dense graphs.

• Journal of Information Processing Systems
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• v.9 no.3
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• pp.477-488
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• 2013

Wireless Sensor Networks (WSNs) are comprised of sensor nodes that forward data in the shape of packets inside a network. Proficient packet forwarding is a prerequisite in sensor networks since many tasks in the network, together with redundancy evaluation and localization, depend upon the methods of packet forwarding. With the motivation to develop a fault tolerant packet forwarding scheme a Self-Localized Packet Forwarding Algorithm (SLPFA) to control redundancy in WSNs is proposed in this paper. The proposed algorithm infuses the aspects of the gossip protocol for forwarding packets and the end to end performance of the proposed algorithm is evaluated for different values of node densities in the same deployment area by means of simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1374-1389
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• 1994

In this paper, a novel M-ary orthogonal CDMA scheme which utilizes time hopping codes and binary orthogonal sequences is proposed for personal communication system. Its modulated output signal has the characteristics of greater bandwidth occupancy and lower spectral density level as well. So this scheme is useful for spectrum overlay with existing narrowband communication systems which occupy current radio frequency channels. This paper investigates system characteristics through the analysis of modulated output signal power spectrum, and demonstrates the possibility of spectrum overlay.

• Journal of the Korean Graphic Arts Communication Society
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• v.20 no.2
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• pp.69-83
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• 2002

This research attempts on plate making for gravure. Direct Hard Dot Method, Helio Kliso Graph, and Laser TB Dot; these three method are the most popular in Korea. For examining ink transmission, three plates were made in the above three different way for the same manuscript and were printed under the same condition. After printing speed was also varied into 150line/inch, 175line/inch, and 200line/inch, ink transmission was examined too. After printing the same manuscript with the above three method then the researcher examined level of ink transmission. Printing lines shows that Laser TB Dot Method and Direct Hard Dot Method were favorable level, while there was big differences of state of Helio Kliso Graph plate.

• Journal of the Korean Graphic Arts Communication Society
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• v.25 no.2
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• pp.1-13
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• 2007

The rheological properties of an ink relate to its performance on the press and to the printing quality. So it is necessary to analyze the relationship between printability and the rheological properties of ink. Transfer rate of ink is one of the important factor deciding print quality. And it is concerned with rheological properties of ink. Thus, in this study, according to the molecular weight of rosin modified phenolic resin the rheological properties of ink were measured by rotational rheometer and then transfer equation of ink, density and gloss were measured in order to examine the printability of ink.