• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.1
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• pp.9-15
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• 1997

In this paper, the performance of a hybrid direct-sequence/slow-frequency-hoped (DS/SFH) spread-spectrum (SS) system with noncoherent DPSK modulation is considered. Th ebit error probability is derived ovef a rayleigh fading channel in the presence of multiple tone jamming. Numerical evaluations are presented for some combinations of system parameters. The performance of a hybrid DS/SFH SS system is shown to be inferior to that of a pure DS SS system at low jamming-to-signal power ratio (JSR). At high JSR, the performance of a pure DS SS system is shown to be the same as the worst case peformance of a hybrid DS/SFH SS system.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.701-706
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• 1989

This study has been aimed to analize and evaluate the performance of the coding algorithms for the handwritten signals such as the telewriting systems. Zone Coding and Differential Chain Coding algorithms have been analized and evaluated on the basis of time and space complexities. According to the simulation results, Zone Coding algorithm has shown better decoding performance from the viewpoint of the Root Mean Square decoding errors, but Differential Chain Coding algorithm has shown better data compression ratio and flexibility of its usage, along with its moderate decoding RMS errors.

• Nuclear Engineering and Technology
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• v.41 no.3
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• pp.225-236
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• 2009

This study has identified human performance research issues associated with the implementation of new technology in nuclear power plants (NPPs). To identify the research issues, current industry developments and trends were evaluated in the areas of reactor technology, instrumentation and control technology, human-system integration technology, and human factors engineering (HFE) methods and tools. The issues were prioritized into four categories based on evaluations provided by 14 independent subject matter experts representing vendors, utilities, research organizations and regulators. Twenty issues were categorized into the top priority category. The study also identifies the priority of each issue and the rationale for those in the top priority category. The top priority issues were then organized into research program areas of: New Concepts of Operation using Multi-agent Teams, Human-system Interface Design, Complexity Issues in Advanced Systems, Operating Experience of New and Modernized Plants, and HFE Methods and Tools. The results can serve as input to the development of a long-term strategy and plan for addressing human performance in these areas to support the safe operation of new NPPs.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.8
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• pp.23-32
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• 1993

This paper presents a decomposition method to evaluate the performance measures of the serial production lines with unreliable machines and finite buffers. This method is to decompose the transfer line into a set of two machine lines for analysis. Bases on this approximation method, we consider nonhomogeneous lines. In such lines, the machines may take the different lengths of time performing operations on parts. A new transformation is employed in order to replace the line by a homogeneous line. The approximate transformation enables one to determine parameters of performance such as production rate and average buffer levels, and it also shows better application for a large class of systems.

• Journal of Communications and Networks
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• v.16 no.6
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• pp.645-655
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• 2014

Latency, an identified element of Internet protocol (IP) mobility protocol execution, can reduce handover performance in mobile networks. Although the performance can be improved by applying an effective network-based IP mobility scheme in place of the traditional host-based alternatives, the existing inter-domain extensions of network-based IP mobility continue to suffer from an extended handover latency. This paper proposes a new inter-domain network-based IP mobility scheme based on node movement prediction. The proposed scheme accelerates the handover by preparing the future domain of the mobile node in a proactive manner. Analytical and simulation-based evaluations confirm improved performance of the proposed scheme in terms of handover latency and packet loss compared with existing schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2687-2702
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• 1996

It is desirable that the implementation of next generation information infrastructure is the Integrated Network combining the satellite and the terrestrial network. The application of the ATM network being the dominant infrastrure of terrestrial network to the satellite network is being studied variously. Considering these concepts, this paper analyzes due to ATM transport via satellite, evaluates the degradation of QoS and proposes reliable method of ATM cell transport via satellite. Because ATM is investigated with the optical fiber which is almost error free characteristics, the practical application of ATM transport via satellite essentially need the channel coding(FEC:Forward Error Correction) to enhance BER performance. But using the FEC coding, satellite link has burst error characteristics which evoke severe performance degradation fo ATM QoS. Therefore in satellite link, we analyze burst error characteristics using experimental results of computer simulation. Then to compensate these characteristics, based on this analysis and HEC dual mode algorithm we propose various interleaver structures(Block interleaver, Intra interlever, and Inter-Intra interleaver) to improve cell transmission QoS. We execute performance evaluations of iterleaver structures by computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1998-2004
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• 1997

In this paper, we have analyzed the bit error performance ofthe chip-spreading OCDM system proposed in the previous papaer and compared the results, through computer simulations, with those of conventional DS/CDMA system which employs the maximal ration combining method. WE have shown, analytically, that the BER upper bound of the OCDM system coincides with that of the conventional DS/CDMA system and the lower bound exhibits much improved results. From the simulation results, we have confirmed that the BER curves of proposed OCDM system actually lie between the two theoretical bounds and its performance is superior to that of the DS/CDMA system.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.2
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• pp.194-201
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• 2010

This paper discuss a performance evaluation of the synchronization algorithm for hybrid networks in industrial environments. The proposed algorithms minimizes synchronization errors which were caused from channel, Propagation, and frequency delays. The modified RBS and offset synchronization methods can be operated by adjustment parameters. The differential BP (Back-off Period) adjustment can synchronize the local time of each node with master node's time in hybrid networks. For the performance analysis, the data transmission time between the wired and wireless devices are investigated. The experimental results show the performance evaluations in terms of the polling service time and an average end-to-end delay.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.297-305
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• 2006

High-rate wireless personal area network (HR-WPAN) has been standardized by the IEEE 802.15.3 task group (TG). To support multimedia services, the IEEE 802.15.3 TG adopts a time-slotted medium access control (MAC) protocol controlled by a central device. In the time division multiple access (TDMA)-based wireless packet networks, the packet scheduling algorithm plays a key role in quality of service (QoS) provisioning for multimedia services. In this paper, we propose an adaptive cross-layer packet scheduling method for the TDMA-based HR-WPAN. Physical channel conditions, MAC protocol, link layer status, random traffic arrival, and QoS requirement are taken into consideration by the proposed packet scheduling method. Performance evaluations are carried out through extensive simulations and significant performance enhancements are observed. Furthermore, the performance of the proposed scheme remains stable regardless of the variable system parameters such as the number of devices (DEVs) and delay bound.

• Journal of information and communication convergence engineering
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• v.18 no.4
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• pp.222-229
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• 2020

Recent multi-core processors for smart devices use per-core dynamic voltage and frequency scaling (DVFS) that enables independent voltage and frequency control of cores. However, because the conventional task scheduler was originally designed for per-core DVFS disabled processors, it cannot effectively utilize the per-core DVFS and simply allocates tasks evenly across all cores to core utilization with the same CPU frequency. Hence, we propose a novel task scheduler to effectively utilize percore DVFS, which enables each core to have the appropriate frequency, thereby improving performance and decreasing energy consumption. The proposed scheduler classifies applications into two types, based on performance-sensitivity and allows a performance-sensitive application to have a dedicated core, which maximizes core utilization. The experimental evaluations with a real off-the-shelf smart device showed that the proposed task scheduler reduced 13.6% of CPU energy (up to 28.3%) and 3.4% of execution time (up to 24.5%) on average, as compared to the conventional task scheduler.