• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.1
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• pp.47-52
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• 2004

This paper presents a CMOS optical receiver design featuring wide input dynamic range and low bit error rate suitable for FTTH application. We achieved 60dB input dynamic range for up to 100Mbps by controlling the PMOS feedback resistance of transimpedance preamplifier according to its output signal level. Auto-bias circuit is designed in current mirror configuration to minimize duty error. Circuit simulation has been performed using 2-poly, 3-metal, 0.6um CMOS process parameters. The designed receiver consumes less than 130mW at 100Mbps with 5V power supply.

• Journal of Distribution Science
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• v.14 no.2
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• pp.41-45
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• 2016

Purpose - Finding an optimal path is an essential component for the design and operation of smart transportation or logistics network. Many applications in navigation system assume that travel time of each link is fixed and same. However, in practice, the travel time of each link changes over time. In this paper, we introduce a new transportation problem to find a latest departing time and delivery path between the two nodes, while not violating the appointed time at the destination node. Research design, data, and methodology - To solve the problem, we suggest a mathematical model based on network optimization theory and a backward search method to find an optimal solution. Results - First, we introduce a dynamic transportation problem which is different with traditional shortest path or minimum cost path. Second, we propose an algorithm solution based on backward search to solve the problem in a large-sized network. Conclusions - We proposed a new transportation problem which is different with traditional shortest path or minimum cost path. We analyzed the problem under the conditions that travel time is changing, and proposed an algorithm to solve them. Extending our models for visiting two or more destinations is one of the further research topics.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.2
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• pp.50-59
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• 1998

This paper presents stabilization and adaptive control of flexible single link robot manipulator system by self-recurrent neural networks that is one of the neural networks and is effective in nonlinear control. The architecture of neural networks is a modified model of self-recurrent structure which has a hidden layer. The self-recurrent neural networks can be used to approximate any continuous function to any desired degree of accuracy and the weights are updated by feedback-error learning algorithm. When a flexible manipulator is rotated by a motor through the fixed end, transverse vibration may occur. The motor toroque should be controlled in such a way that the motor rotates by a specified angle, while simultaneously stabilizing vibration of the flexible manipuators so that it is arresed as soon as possible at the end of rotation. Accurate vibration control of lightweight manipulator during the large changes in configuration common to robotic tasks requires dynamic models that describe both the rigid body motions, as well as the flexural vibrations. Therefore, a dynamic models for a flexible single link robot manipulator is derived, and then a comparative analysis was made with linear controller through an simulation and experiment. The results are proesented to illustrate thd advantages and imporved performance of the proposed adaptive control ove the conventional linear controller.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.9-14
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• 2004

As the internet traffic type and size have bun diversified in recent years, the GMPLS-based distributed control and management protocol have surfaced as a serious issue for dynamic optical lightpath setup. In this reason, we investigated and analyzed network performance and protocols using global information-based link state approach and local information based link state approach. We calculated connection setup time, required control bandwidth and setup blocking probability that made from network update period and threshold metrics according to traffic arrival rate. The evaluated results will be used in broadband network and adopted for high speed network in the future widely.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.118-123
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• 2015

The study of input and output characteristics in dynamic motion control is important indicator of the performance of mechanical equipment and is the factors to be considered during commissioning and maintenance of machinery or equipment, and project planning. The Analysis on dynamical characteristic of the input/output of the automation solution that used for motion control in machinery, is represented the control performance of device and including controller which connected at automation network by considering period of the frequency as applied load. This paper was constructed the simulator of B & R Powerlink to be widely used for motion control in the machine and showed the dynamic system characteristics by analysing the period.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.6
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• pp.614-620
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• 2006

Today the automobile has been changed from a mechanical system to an electronic control system fly the development of the electronic technology. In the automobile body, most of these electronic control devices are networked and managed fully by the CAN protocol. But, when a network system is overloaded, unexpected transmission delay for relative low priority objects occurs due to the static priority definition of the CAN protocol. To resolve this problem, this paper proposes a dynamic precedence queue mechanism that creates a queue for the low priority object and its relevant objects to be transmitted, which becomes urgent in an overloaded network system to keep the maximum allowable time delay. For the generated queue, the highest priority is assigned to transmit the queued objects within the shortest time. The mechanism is implemented in the logical link layer of CAN, which does not require any modification of the old CAN hardware. Effectiveness of the proposed mechanism is verified by the real experiments with an automobile network system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.11
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• pp.3163-3181
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• 2023

Eavesdropping attacks have seriously threatened network security. Attackers could eavesdrop on target nodes and link to steal confidential data. In the traditional network architecture, the static routing path and the important nodes determined by the nature of network topology provide a great convenience for eavesdropping attacks. To resist monitoring attacks, this paper proposes a random routing mutation defense method based on dynamic path weight (DPW-RRM). It utilizes network centrality indicators to determine important nodes in the network topology and reduces the probability of important nodes in path selection, thereby distributing traffic to multiple communication paths, achieving the purpose of increasing the difficulty and cost of eavesdropping attacks. In addition, it dynamically adjusts the weight of the routing path through network state constraints to avoid link congestion and improve the availability of routing mutation. Experimental data shows that DPW-RRM could not only guarantee the normal algorithmic overhead, communication delay, and CPU load of the network, but also effectively resist eavesdropping attacks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.72-84
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• 2005

Optical burst switching networks usually employ one-way reservation by sending a burst control packet with a specific offset time, before transmitting each data burst Same. Due to such a Property, burst-contentions occur when multiple bursts contend for the same wavelength in the same output link simultaneously in a node, leading to burst losses, eventually degrading the quality of service. Therefore, in this paper, we propose a dynamic routing algorithm using minimum local state information in order to decrease burst-contentions. In this proposed scheme, if burst loss rate exceeds a threshold value at a certain node, a new alternative routing path is chosen according to burst priority and location of burst generation, which enables the contending bursts to detour around the congested link. Moreover, for reducing the effect of sending bursts on the primary path due to the alternative path, we also apply a minimum path-cost based routing on link-cost concept. Our simulation results show that proposed scheme improves the network performance in terms of burst loss probability and throughput by comparing with conventional one.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.5
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• pp.53-61
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• 2004

This paper proposes two types of sub-network based on dynamic restoration schemes to improve survivability of GMPLS networks and analyzes characteristics of these two schemes. The first proposed scheme divides with a whole GMPLS network into several sub-networks, applies a mixture of both restoration and protection methods according to fault location. The other scheme divides a whole GMPLS network into primary and secondary sub-networks, applies a restoration method in each sub-network according to fault location. In our simulation, we evaluate the performances of network resource utilization, restoration success rate, and mean restoration time and conduct its comparative analysis with conventional schemes. The simulation results show that the efficiency of network resource utilization in the proposed schemes is increased as compared with conventional restoration schemes (l＋l, 1:1, 1:N) in case of single-failed link. By contrast, we found that the performances of restoration success rate and mean restoration time in case of multi-failed link is lower than conventional restoration schemes. However, the probability that multi-failed link is occurred is very low so that the problem in practical GMPLS network is negligible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.844-851
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• 2004

Various types of error are caused due to many factors of various environment in air interface channel of wireless communications. In this case, the reliability of the channel is much lower than that of wired case. IEEE 802.15.3 high-rate WPAN, which operates in an ad hoc networking environment, is more susceptible to such errors. The problem has been investigated for wireless LANs, for example, as follows. If the queue size of a certain node is longer than that of other nodes, the node estimates that its channel state is bad and the resource of the node is decreased. However this method has a disadvantage that a central controller must always monitor the status. To avoid this disadvantage, in this paper, a new MAC protocol that the throughput of overall piconet is increased by LDS (Link-status Dependent Scheduling) is proposed.