• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1C
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• pp.59-64
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• 2004

We propose a new RLL(run length limited) (2,7) PP(parity preserving) code with 4 RMTR(repeated minimum transition run) for optical recording. The proposed code has better characteristics in terms of density ratio, RMTR, DC(direct current) component suppression, BER(bit error rate) and system complexity than (2,1O) code that currently applied in storage systems and (1,7) PP code that highly recommended as the next generation optical recording system. Some characteristics of the code are described with several simulations. And the proposed code's superiorites in performance is illustrated as compared with the other codes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.676-679
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• 2001

As network security is coning up with significant problem after the major Internet sites were hacked nowadays, IDS(Intrusion Detection System) is considered as a next generation security solution for more reliable network and system security rather than firewall. In this paper, we propose the new IDS model which tan detect intrusion in different systems as well as which ran make real-time detection of intrusion in the expanded distributed environment in host level of drawback of existing IDS. We implement its prototype and verify its validity. We use pattern extraction agent so that we can extract automatically audit file needed in distributed intrusion detection even in other platforms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1966-1973
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• 1999

In this paper, we introduce the concept of a HAPS(High Altitude Platform Station) system which is expected to be a next generation communication system and suggest several error correcting codes to provide high quality services. Since a HAPS system encounters serious signal attenuation due to rain and scattering in the air, concatenated codes which have a high coding gain is considered to be a proper error correcting method. In this paper, we provide performance analyses result of two candidate coding schemes for a HAPS. The first one is a conventional concatenated coding scheme, and the second one is a iterative decoding method known as Turbo Codes.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.4
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• pp.19-26
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• 2011

Relay-assisted multiple input multiple output (MIMO) technique has become a promising candidate for next generation broadband wireless communications. In this paper, we propose maximum ratio combining (MRC) minimum mean-square-error (MMSE) equalization for single carrier-frequency domain equalizer (SC-FDE) in amplify-and-forward (AF) relaying networks. The performance of SC-FDE system can be improved considerably by achieving both the diversity gain and the MMSE equalization gain when the signals from source-destination (S->D) and source-relay-destination (S->R->D) are combined and equalized by means of the MMSE criteria. We find the weighting coefficients of MRC combining and the tap coefficients of MMSE equalizer for SC-FDE in AF relaying networks. Simulation results show that the proposed relay-based system considerably outperforms the conventional SC-FDE system.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.1
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• pp.99-104
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• 2014

Nowadays, various researches fulfill in many communication engineering area for B4G (Beyond Forth Generation). Next LTE-A (Long Term Evolution Advanced), MU-MIMO (Multi-User Multi Input Multi Output) method raises to upgrade throughput performance. However, the method of user selection is not decided because of many types and discussions in MU-MIMO system. Many existing methods are powerful for enhancing performance but have various restrictions in practical implementation. Fairness problem is primary restriction in this area. Existing papers emphasis algorithm to increase sum-rate but we introduce an algorithm about dealing with fairness problem for real commercialization implementation. Therefore, this paper introduces new user selection method in MU-MIMO system. This method overcomes a fairness problem in SUS (Semiorthogonal User Selection) algorithm. We can use the method to get a similar sum-rate with SUS and a high fairness performance. And this paper uses a hybrid method with SC-SUS (Superposition Coding SUS) algorithm and SUS algorithm. We find a threshold value of optimal performance by experimental method. We show this performance by computer simulation with MATLAB and analysis that results. And we compare the results with another paper's that different way to solve fairness problem.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.371-384
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• 2001

In these days, it is continuously increased to the intrusion of system in internet environment. The methods of intrusion detection can be largely classified into anomaly detection and misuse detection. The former uses statistical methods, features selection method in order to detect intrusion, the latter uses conditional probability, expert system, state transition analysis, pattern matching. The existing studies for IDS(intrusion detection system) use combined methods. In this paper, we propose a new intrusion detection algorithm combined both state transition analysis and association mining techniques. For the intrusion detection, the first step is generated state table for transmitted commands through the network. This method is similar to the existing state transition analysis. The next step is decided yes or no for intrusion using the association mining technique. According to this processing steps, we present the automated generation algorithm of the penetration scenarios.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.462-464
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• 2015

Since the first Aegis Cruiser USS Ticonderoga was constructed, Arleigh Burke class destroyers are being mass constructed as U.S. Naval capital surface ships and consistently improved the performance. In recent years, the newest aegis combat system, Baseline 9, was deployed. Aegis BMD, aegis ships which have BMD capability, is participated BMDS(Ballistic Missile Defense System) as a sea based BMD. And AN/SPY-1D will be replaced by AMDR(Air & Missile Defense Radar), advanced anti-air radar system to defend effectively against increased ballistic missiles threat from DDG-51 Flight III. In this paper, development status and technical characteristics of each type of aegis ships are researched and characteristics of AMDR are surveyed and described.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7A
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• pp.629-634
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• 2002

The next generation of wireless communication system is expected to provide users with wireless multimedia services such as high speed internet access and wireless mobile computing. Depending on the Quality of Service(QoS) requirements and different applications per user, many wireless communication systems have been proposed. The simple decoding algorithm of space-time block coding is based on the assumption of flat fading channel, where no intersymbol interference exists. In this paper, we propose to combine space-time transmit diversity with adaptive equalizer. The proposed system effectively eliminates interference caused by multipath environment. Simulation results show that the proposed system provides improved bit error rate performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1940-1946
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• 2015

An optical coherent system is considered for the next-generation optical access networks in enhancing the data rate and transmission distance. In this system, however, I/Q amplitude imbalance may occur at several parts of the system, leading to serious performance degradation. Asymmetric structure of a coherent receiver at the location of subscriber is one of the sources of I/Q imbalance. Therefore, this imbalance parameters must be removed or compensated to secure the transmission performance. In this paper, the source of I/Q amplitude imbalance is analyzed, and then the way to compensate for the imbalance at the receiver side is suggested. Performance after the compensation is estimated using simulation.

• Transactions of the Society of Information Storage Systems
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• v.7 no.1
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• pp.25-30
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• 2011

In the last couple of years, the flexible optical disk(FOD) system that consists of a thin polycarbonate(PC) film of 95 ${\mu}m$ thick, a rigid stabilizer, and a high speed spindle motor has been spot-lighted as the next-generation optical system for archival use of digital data. The air film between the rotating disk and stabilizer provides a means for damping out the lateral disk vibrations. However, its damping-capability drops significantly as the rotational speed of the disk exceeds a specific limit and, eventually, the disk vibration propagates inward causing the whole span of the disk exhibits large vibration amplitudes. Based on the numerical simulations as well as the experimental results, the present work aims to evaluate the damping coefficient of the air-film near the outer region of the disk where the capillary type orifices are applied to the edge of the curved stabilizer.