• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.663-673
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• 2002

Server-side anti-viruses are useful to protect their domains, because they can detect malicious codes at the gateway of their domains. In prevailing local network, all clients cannot be perfectly controlled by domain administrators, so server-side inspection, for example in e-mail server, is used as an efficient technique of detecting mobile malicious codes. However, current server-side anti-virus systems perform only signature-based detection for known malicious codes, simple filtering, and file name modification. One of the main reasons that they don't have detection features, for unknown malicious codes, is that activity monitoring technique is unavailable for server machines. In this paper, we propose a detection technique that is executed at the server, but it can monitor activities at the clients without any anti-virus features. we describe its implementation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.43-47
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• 2000

In regions of low signal-to-noise ratio (SNR), performance analysis uses simulations of hybrid concatenated coding systems. However, for higher SNR regions beyond simulation capabilities, average upper bounds to bit error rate (BER) and word error rate (WER) are used. In [1], all weight enumerating functions are needed to obtain average bounds. In this paper, we use RSC as constituent codes, by using effective free distances instead of WEF, we derive average BER and WER bounds of hybrid concatenated convolutional codes (HCCC) and analyze the BER and WER over AWGN and Rayleigh/Rician fading channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1080-1089
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• 1999

The union upper bounds to the bit error probability of maximum likelihood(ML) soft-decoding of parallel concatenated convolutional codes(PCCC) and serially concatenated convolutional codes(SCCC) can be evaluated through the weight enumerating function(WEF). This union upper bounds become the lower bounds of the BER achievable when iterative decoding is used. In this paper, to compute the WEF, an efficient error event search algorithm which is a combination of stack algorithm and bidirectional search algorithm is proposed. By computor simulation, it is shown that the union boounds obtained by using the proposed algorithm become the lower bounds to BER of concatenated convolutional codes with iterative decoding.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.10
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• pp.610-612
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• 2014

Mutilevel holographic data storage systems have a big advantage for capacity since it can store more than one bit per pixel. For instance, 2/3 modulation code stores 2/3(symbol/pixel) and 4/3(bit/pixel). Then it is about 1.3 bits per one pixel. In this paper, we propose two 4-level modulation codes, which have the minimum Euclidean distances of 3 and 4, respectively. The proposed codes perform better than random data. The performance of larger minimum distance code shows better than that of shorter one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6B
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• pp.1100-1105
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• 2000

The most widely used radar pulse compression technique is correlation processing using Barker code. This technique enhances detection sensitivity but, unfortunately, suffers from the addition of range sidelobes which sometimes will degrade the performance of radar systems. In this paper, our proposed optimal algorithm eliminates the sidelobes at the cost of additional processing and is evaluated in the presence of Doppler shift. We then propose optimal codes with regard to the proposed algorithm and the performance is compared against the traditional correlation processing with Barker codes. The proposed processing using optimal codes will be shown to be superior over the traditional processing in the presence of Doppler shift.

• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.907-910
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• 2009

This paper is the FPGA Implementation of Reed-Solomon Encoder that is one of Error control Codes. Reed-Solomon codes are block-based error control codes with a wide range of applications in digital communications. RS codes are strong on burst errors because it process signals as symbol. We simulate this system using Matlab from Mathworks and design it using System Generator from Xilinx. We refer Matlab source in Implementation of Reed-Solomon Error Control Coding for Compressed Images by Simon Anthony Raspa.

• Journal of the Korea Society of Computer and Information
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• v.24 no.5
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• pp.27-33
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• 2019

One of serious security threats is a botnet-based attack. A botnet in general consists of numerous bots, which are computing devices with networking function, such as personal computers, smartphones, or tiny IoT sensor devices compromised by malicious codes or attackers. Such botnets can launch various serious cyber-attacks like DDoS attacks, propagating mal-wares, and spreading spam e-mails over the network. To establish a botnet, attackers usually inject malicious URLs into web source codes stealthily by using data hiding methods like Javascript obfuscation techniques to avoid being discovered by traditional security systems such as Firewall, IPS(Intrusion Prevention System) or IDS(Intrusion Detection System). Meanwhile, it is non-trivial work in practice for software developers to manually find such malicious URLs which are hidden in numerous web source codes stored in web servers. In this paper, we propose a security defense system to discover such suspicious, malicious URLs hidden in web source codes, and present experiment results that show its discovery performance. In particular, based on our experiment results, our proposed system discovered 100% of URLs hidden by Javascript encoding obfuscation within sample web source files.

• Wind and Structures
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• v.34 no.4
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• pp.371-383
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• 2022

Buildings with mono-sloped roofs are used for different purposes like at railway platforms, restaurants, industrial buildings, etc. Between two types of mono-slope roofs, clad and unclad, unclad canopy types are more vulnerable to wind load as wind produces pressure on both upper and lower surfaces of the roof, resulting in uplifting of the roof surface. This paper discusses the provisions of wind loads in different codes and standards for Low-rise buildings. Further, the pressure coefficients on mono-slope canopy roof available in wind code and standards are compared. Previous experimental studies for mono-slope canopy roof along with the recent wind tunnel testing carried out at Indian Institute of Technology, Roorkee is briefly discussed and compared with the available wind codes. From the study it can further be asserted that the information available related to staging or blocking under the mono-slope canopy roofs is limited. This paper is an attempt to put together the available information in different wind codes/standards and the research works carried out by different researchers, along with shedding some light on the future scopes of research on mono-slope canopy roofs.

• Journal of information and communication convergence engineering
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• v.5 no.2
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• pp.88-92
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• 2007

In this paper, an SS-RRA protocol that is based on Code Division Multiple Access is proposed and analyzed under the integrated voice and data traffic load. The backward logical channels consist of slotted time division frames with multiple spreading codes per slot. The protocol uses a reservation mechanism for the voice traffic, and a random access scheme for the data traffic. A discrete-time, discrete-state Markov chain is used to evaluate the performance. The numerical results show that the performance can be significantly improved by a few distinct spreading codes.