• International Journal of Contents
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• v.11 no.1
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• pp.7-14
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• 2015

In this paper, we derive the outage probability for M-ary phase shifting keying (MPSK) and M-ary quadrature amplitude modulation (MQAM) burst transmission (BT) of adaptive decode-and-forward (ADF) cooperative relay systems over quasi-static Rayleigh fading channels. Within a burst, there are pilot symbols and data symbols. Pilot symbols are used for channel estimation schemes and each relay node's transmission mode selection schemes. At first, we focus on ADF relay systems in which the probability density function (PDF) is derived on the basis of error events at relay nodes corresponding to channel estimation errors. Next, the average outage probability is derived as an approximate expression for an arbitrary link signal-to-noise ratio (SNR) for different modulation orders. Its accuracy is demonstrated by comparison with simulation results. Further, it is confirmed that BT-ADF relay systems with pilot symbol based channel estimation schemes enables to select correctly decoded relay nodes without additional signaling between relay nodes and the destination node, and it is verified that the ideal performance is achieved with small SNR loss.

• Water for future
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• v.21 no.2
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• pp.173-182
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• 1988

Characteristics of finite difference schemes for St. Venant equation were compared with two input cases. One is the monoclinal wave which has large friction slope without discontinuity and the other is the shock wave with discontinuity. For monoclinal wave, Keller Box scheme is the best in terms of accuracy, efficiency and stability when two parameters were selected with a rele : $0.5{\leq}{\theta}{\leq}1.0$, ${\theta}+{\psi}$=1, But for shock wave only the Preissmann type of parameter ${\psi}$(=0.5) showed stable results. Numerical experiments of monoclinal wave showed that Lax-Wendroff and Richtmyer schemes were more stable than leap Frog and more accurate than Lax-Fredrich scheme. For shock wave Lax-Fredrich showed larger numerical dissipation than other explicit schemes and Leap Frog produced slower mass transport.

• The Korean Journal of Quaternary Research
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• v.22 no.1
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• pp.13-22
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• 2008

The Indian summer monsoon behaved in an abnormal way in 2002 and as a result there was a large deficiency in precipitation (especially in July) over a large part of the Indian subcontinent. For the study of deficient monsoon of 2002, a recent version of the NCAR regional climate model (RegCM3) has been used to examine the important features of summer monsoon circulations and precipitation during 2002. The main characteristics of wind fields at lower level (850 hPa) and upper level (200 hPa) and precipitation simulated with the RegCM3 over the Indian subcontinent are studied using different cumulus parameterization schemes namely, mass flux schemes, a simplified Kuo-type scheme and Emanuel (EMU) scheme. The monsoon circulation features simulated by RegCM3 are compared with the NCEP/NCAR reanalysis and simulated precipitation is validated against observation from the Global Precipitation Climatology Centre (GPCC). Validation of the wind fields at lower and upper levels shows that the use of Arakawa and Schubert (AS) closure in Grell convection scheme, a Kuo type and Emanuel schemes produces results close to the NCEP/NCAR reanalysis. Similarly, precipitation simulated with RegCM3 over different homogeneous zones of India with the AS closure in Grell is more close to the corresponding observed monthly and seasonal values. RegcM3 simulation also captured the spatial distribution of deficient rainfall in 2002.

• Convergence Security Journal
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• v.15 no.5
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• pp.37-45
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• 2015

In IT system, logs are an indicator of the previous key events. Therefore, when a security problem occurs in the system, logs are used to find evidence and solution to the problem. So, it is important to ensure the integrity of the stored logs. Existing schemes have been proposed to detect tampering of the stored logs after the key has been exp osed. Existing schemes are designed separately in terms of log transmission and storage. We propose a new log sys tem for integrating log transmission with storage. In addition, we prove the security requirements of the proposed sc heme and computational efficiency with existing schemes.

• Water for future
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• v.29 no.1
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• pp.203-212
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• 1996

The subject research attempts to develop a new temporal interpolation scheme for the method of characteristics. The proposed three-point time-line Lagrange interpolation Reachback (3PR) method is a temporal quadratic interpolation scheme using the three grid points near the intersection between a characteristic line and a previous time-line. The accuracy of the 3PR method is compared with those of temporal and spatial interpolation schemes such as Reachback, Upwind, and quandratic spatial interpolation methods for two pure advection problems. The results show that on the aspects of the numerical damping and/or oscillation the temporal interpolation schemes are better than the spatial ones under the same interpolation order conditions. In addition, the spatial ones under the same interpolation order conditions. In addition, the proposed 3PR method improves the accuracy of Reachback method as well as it contains the merits of time-line interpolation schemes.

• Journal of Korea Port Economic Association
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• v.29 no.2
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• pp.173-194
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• 2013

This paper aims at drawing policy schemes to establish marine clusters so as to enhance Korea's global port competitiveness and applying them to its national management for the advancement of national economy through policy suggestions. The research method is an integrated approach(IA) that comprises SWOT Method with strategic approaches, HFP Model enhanced by KJ Method and descriptive deductions. Strategic schemes established for the SPLC are followed by the group of geographical proximity, integration of ICT, expansion of the interchange of ICT & opportunities of ET, integration of ICT services with marine technologies, supply of integrated services in the SPLC and implementation of organizational policies. In order to make a specific implementation of strategic establishment schemes of the SPLC, we need to select a promotion entity. It is advised to establish the joint organization of the public sector and the private sector, which is considered most desirable. In practice, it is to be followed by promoting support schemes of the organizational policy on the level of national management. In order to reinforce this study, further compensative and proactive researches on the offshore sector with marine clusters are required in terms of the development of the high value added 'blue' ocean.

• Journal of The Korean Association of Information Education
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• v.15 no.1
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• pp.129-136
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• 2011

The aim of this study is to present the handover procedures and the performance comparisons of layered mobility management schemes for wireless mobile Internet. To investigate efficient mobility management schemes providing seamless information services in a mobile environment, this paper provided the detailed discussions of existing network layered mobility management scheme, including Mobile IPv4, Mobile IPv6, and new transport layer mobility management scheme, stream control transmission protocol (SCTP) based mobility architecture (SMA). Network simulator-2 (ns-2) was used to compare the performance between Mobile IPv6 and SMA in the wireless mobile Internet environment. Simulation results show that for typical network configuration and parameters, SMA has a lower handover latency, lower packet loss rate, and higher throughput than Mobile IPv6.

• Journal of the Korean Association of Geographic Information Studies
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• v.3 no.1
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• pp.57-68
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• 2000

The purpose of this study is to find the most effective method of the coding methods by linking the attribute information with the digital map in Taegu metropolitan city. This study was also a precedent plan for street trees management information system and the coding schemes for street trees management information system could be summarized as follows; First, this study extracted 11 coding factors for expressing the position of street trees. Second, 11 coding schemes were made out of these coding factors and applied to the digital map(1:500). Third, two methods of 11 coding schemes were selected for street trees management information system of Taegu metropolitan city. The one was the method which applied serial numbers according to the block name. The other was the method utilizing the concept of 'dynamic segment'. Finally, this study will be the first step for the computerization and management of the street trees information and this computerized data will do for the management efficiency of the street trees on internet.

• International Journal of Contents
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• v.7 no.4
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• pp.1-5
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• 2011

Physics based fluid animation schemes need large computation cost due to tremendous degree of freedom. Many researchers tried to reduce the cost for solving the large linear system that is involved in grid-based schemes. GPU based algorithms and advanced numerical analysis methods are used to efficiently solve the system. Other groups studied local operation methods such as SPH (Smoothed Particle Hydrodynamics) and LBM (Lattice Boltzmann Method) for enhancing the efficiency. Our method investigates this efficiency problem thoroughly, and suggests novel paradigm in fluid animation field. Rather than physics based simulation, we propose a robust boundary handling technique for procedural fluid animation. Our method can be applied to arbitrary shaped objects and potential fields. Since only local operations are involved in our method, parallel computing can be easily implemented.

• International Journal of Contents
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• v.14 no.1
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• pp.18-27
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• 2018

The objective of this study was to derive approximate closed-form error rates for M-ary burst symbol transmission (MBST) of dual-hop adaptive decode-and-forward (ADF) cooperative relay systems over quasi-static Rayleigh fading channels. Within a burst, there are pilot symbols and data symbols. Pilot symbols are used for channel estimation schemes and each relay node's transmission mode selection schemes. At first, our focus was on ADF relay systems' error-events at relay nodes. Each event's occurrence probability and probability density function (PDF) were then derived. With error-event based approach, we derived a tractable form of PDF for combined signal-to-noise ratio (SNR). Averaged error rates were then derived as approximate expressions for arbitrary link SNR with different modulation orders and numbers of relays. Its accuracy was verified by comparison with simulation results.