• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.699-705
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• 2012

In this paper, an infrastructure-based localization method using underwater wireless sensor network (UWSN) is addressed. A localization using the UWSN is necessary to widen the usage of underwater applications, however it is very difficult to establish the UWSN due to the restrictions of water. In this paper, to extend the usage of UWSN at the infrastructure, we propose a sophisticated UWSN localization method using the Received Signal Strength Indicator (RSSI) of the electromagnetic waves. During the electromagnetic waves propagating in underwater, there arises a lot of attenuation according to the distance, while the attenuation shows uniformity according to the distance. Using this characteristics, the localization system in underwater infrastructure is proposed and the experimental results show the effectiveness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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• pp.1116-1125
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• 1997

In this paper, the modified UPC(Usage Parameter Control) algorithm is proposed. The proposed UPC algorithm is based on Leakey Bucket algorithm and adds the characteristics of the jumping window algorithm for monitoring the average bit rate. The proposed algorithm let a cell, which is tagged by Leaky Bucket algorithm, pass through the network, if the network does not violate the average bit rate. The measuring method of window mechanism like jumping window. This paper supposes On/Off traffic source model of rthe performance evaluation and analysis of the proposed algorithm. Therefore, as simulation results, the proposed algorithm acquires more reduced results of the cell loss rate and bucket size than the Leaky Bucket algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.540-543
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• 1997

In this paper, a precise trajectory tracking method for mobile robot using a vision system is presented. In solving the problem of precise trajectory tracking, a hierarchical control structure is used which is composed of the path planer, vision system, and dynamic controller. When designing the dynamic controller, non-ideal conditions such as parameter variation, frictional force, and external disturbance are considered. The proposed controller can learn bounded control input for repetitive or periodic dynamics compensation which provides robust and adaptive learning capability. Moreover, the usage of vision system makes mobile robot compensate the cumulative location error which exists when relative sensor like encoder is used to locate the position of mobile robot. The effectiveness of the proposed control scheme is shown through computer simulation.

• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.1
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• pp.9-15
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• 2018

This paper describes the applicability of Bluetooth and ZigBee networks for real-time control in wireless networked control system and suggests an effective usage of them. The Bluetooth SCO link, SPP and HID profiles and the ZigBee non-beacon enabled network are analyzed and the latency of them are measured. A number of wireless networked control system experiments are performed via DC motor control system and the various profiles of Bluetooth and ZigBee in real-time wireless networked control system are compared.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.421-424
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• 1990

An iterative learning control scheme for exact-tracking control and parameter estimation of uncertain robotic systems is presented. In the learning control structure, tracking and feedforward input converge globally and asymptotically as iteration increases. Since convergence of parameter errors depends only on the persistent exciting condition of system trajectories along the iteration independently of length of trajectories, it may be achieved with only system trajectories of small duration. In addition, these learning control schemes are expected to be effectively applicable to time-varying parametric systems as well as time-invariant systems, for the parameter estimation is performed at each fixed time along the iteration. Finally, no usage of acceleration signal and no in version of estimated inertia matrix in the parameter estimator makes these learning control schemes more feasible.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.688-695
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• 2013

Networked Control Systems(NCS) contain the structure which controllers, actuators and sensors are connected to communication network. And they have been adopted in large and complicated plant area due to the advantages of mitigating computational bottleneck and maintenance. Although this structure provides many benefits, it brings in problems of unpredictable communication delay, data loss and corruption. This phenomena have to be considered in designing NCSs since it affects on overall control system stability. This paper introduces network traffic test method for ethernet based NCSs to find out maximum network usage which guarantee stable control operation. Test results shows this methods can be adopted in various types of NCSs and contributes economical system design and effective system operation.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.116-118
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• 2001

The load bus voltage is controlled by not only using several control device but also generation bus voltage adjustment. This paper deals with a load bus voltage control problem which used optimization and load flow technique. The usage of proposed control algorithm is verified through the comparison with normal load flow on the IEEE 14 sample system. The proposed control algorithm can be used to optimal decision of position and capacity for voltage control device.

• Journal of the Korea Society for Simulation
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• v.8 no.2
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• pp.45-56
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• 1999

It is necessary that we should control the traffic to not only efficiently use the rich bandwidth of ATM network but also satisfy the users various requirements for service quality. However, it is very difficult to decide which control mechanism would be applied in real network because there are various types of ATM traffic and traffic control mechanisms. In this paper, a smart simulator is developed ot analyze the performance of a UPC(Usage Parameter Control) mechanism which is a typical traffic control mechanism. The simulator consists of a user interface that supports a menu-driven input form and a simulation program that is executed with the users input parameters. Especially, the simulator establishes more powerful and flexible simulation environment since it supports a more complex simulation applying various source traffic to several different UPC mechanisms at the same time and allows an arbitrary user-defined traffic in addition to some well-known traffic.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.636-641
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• 2008

In this paper, the analysis methods of available information are reviewed and it is elicited to the method of which the analysis results are applied to the Autonomous Decentralized Train Management System for the optimization at the point of the route control time and for making the efficiency shunting plan in the Autonomous Centralized Station Operation Control System. As the statistics and estimated information which are got through the utilizable information analysis are applied for the automatic route control function and the shunting plan management of the station operation control system, it is possible to use efficiently the station information by the autonomous route control system. And as the exact forecast information needed for the shunting plan establishment and the operation is provided to the operator, it is established to the efficient train operation plan.

• Journal of the Korean Child Neurology Society
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• v.26 no.4
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• pp.251-262
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• 2018

Purpose: This study aimed to identify changes in smart device usage trends of young children using two studies conducted in 2015-2016 and 2017 respectively. Methods: We compared the data of the previous study of 130 children (Group A) and the new study of 162 children (Group B). The children and parents were recruited from kindergartens in Seoul and Guri/Namyangju cities. We used the "Parental questionnaire for smart device usage status." Results: There were some changes in the smart device usage in young children and parental perception. In the 2017 study, smart device usage time increased during weekends (P<0.05) and the usage with siblings decreased (P<0.05). In 2017, the smart device was mostly used when children had to be quiet without disturbing others (36.8%). No significant difference existed in the main purpose of use: watching video clips (79.3% vs 76.6%). Overall control of the usage was still largely exercised by mothers; however, when using applications, mothers still only helped the children on request (51.8% vs 49.7%). Regarding the effect of smart device on children, responses of "not knowing" decreased and "will be negative" and "will be positive" increased (P<0.05). Additionally, most mothers thought that "Although the smart device is currently unnecessary, it will be needed in future" in 2017 (46.3%). Conclusion: Limiting the smart device usage time during the weekends and increasing parental involvements are recommended. Guidelines for smart devices usage in young children are also necessary considering the changes in parental attitudes in recognizing the smart device usage as unavoidable.