• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.157-160
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• 2002

When the teleoperation system has a signal transmission time delay between slave system and control system, the position tracking performance of the slave system and system stability are likely to be deteriorated. This paper proposes a force reflecting position control scheme for teleoperation system with signal transmission time delay. The proposed scheme not only satisfy the system internal stability but also improves the position tracking performance with disturbance rejection capability. The simulation results show that the proposed control method provides excellent performances.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.11a
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• pp.187-190
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• 1997

Test Model15, which is used widely for the MPEG-2 bit rate control, has several problems such as non-unform picture quality, scene change and buffer underflow. Therefore, various algorithms have been developed to solve these problems. In this paper, we study various algorithms for the MPEG-2 bit rate control and compare their performances using software simulations. We also propose a new bit rate control strategy based on coded types of macroblocks within a picture.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.267-270
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• 2002

Downlink Shared Channel (OSCH) is used for high-speed packet service transmission in WCOMA. The power-controlled performances of the OSCH are studied through simulation works. Under various channel conditions and mobile speeds, the simulation results show that current power control scheme in WCDMA, especially for the OSCH power control, has some problems. In this paper, cause of problems is revealed. Also, the quantitative result related to the OSCH power control problem is analyzed.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.899-902
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• 1993

A neural model predictive control strategy combining a neural network for plant identification and a nonlinear programming algorithm for solving nonlinear control problems is proposed. A constrained nonlinear optimization approach using successive quadratic programming combined with neural identification network is used to generate the optimum control law for complex continuous chemical reactor systems that have inherent nonlinear dynamics. The neural model predictive controller (MNPC) shows good performances and robustness. To whom all correspondence should be addressed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.6
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• pp.625-632
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• 1992

This paper presents a new dc-motor position control approached by Variable Structure System. In order to eliminate a steady-state position error, we propose a switching function composed of position error, velocity, and current ripple. The switching function has an advantage compared to other ones. To determine the control signal voltage, we use a fuzzy logic method. The simulation results show expected performances.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.2
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• pp.111-119
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• 2011

Recently, the performances of speed and accuracy are enhanced in machine tools. The high speed of the machine tools usually causes harmful thermal displacements on the objects. To reduce the thermal displacements, machine tools generally adopt oil coolers with precise temperature control function. This study aims at precise control of oil outlet temperature in the oil coolers with hot-gas bypass manner based on PI control logic. The control system was designed for obtaining steady state error within ${\pm}0.1^{\circ}C$ and maximum overshoot with 0.8% even though abrupt disturbances are added to the system. We showed that the PI gains could be easily decided by numerical simulations using practical transfer function which got experiments. Also, transient characteristics could be improved significantly by reflecting the inlet temperature of an evaporator to the output of a controller feedforwardly considering periodic abrupt disturbances. Through some experiments, excellent control performances were established by the suggested control.

• The Journal of the Korea Contents Association
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• v.12 no.2
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• pp.52-59
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• 2012

Recently, LEDs are used in various fields such as lightings, billboards, displays, and so on. In this paper, we tried to combine a costume with LEDs in a performance environment. To meet the environmental requirements, we propose a digital costume platform which consists of wireless network, an embedded system, a control jacket, a digital skin, and a pattern authoring tool. It is utilized for making a digital costume with LED lighting effects. The embedded system controls LED lighting according to the signals from a show control system through wireless networks. The control jacket can carry the embedded system and connect it with LEDs. The digital skin means a costume with LEDs. The LEDs were designed to fit in performance concept in point of aesthetic. The pattern authoring tool enables users to make timeline-based changing patterns of LED lighting. The proposed platform is a new lighting element in performances. It can expand stage representation techniques and be used as a special effect. It will play a role as a moving light in performances. We evaluated stable operations of our platform by employing it in live performances.

• Journal of East-West Nursing Research
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• v.11 no.2
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• pp.137-145
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• 2005

Purpose: This study has been attempted as one of the Quality Improvement activities in order to provide with intravenous injection control and to confirm the evaluation from the patients and their guardians, and also from nurses themselves. Method: The subject of this intravenous injection control was a control group of 239 patients and 176 nurses, a comparison group of 128 patients and 146 nurses. The tool consisted of hospitality (towards patients), explanation, and infection prevention activities. The collected data were analysed using SPSS Windows 11.0 program for percentage, $X^2$-test and t-test. Result: 1) The nurses who were instructed in standardised intravenous injection control received more satisfactory evaluation from the patients(t=-2.89, p=.004) than the nurses who were not. However, in the subdivisions, the explanation field was the only one to receive a more satisfactory evaluation(t=-1.14, p=.255). 2) The nurses who were instructed in standardised intravenous injection control showed higher performances in intravenous injection control (t=-4.21, p=.000) than the nurses who were not. In the subdivisions, hospitality, explanation, and infection prevention activities all showed effectiveness ($t=-2.35{\sim}3.90$, $p=.020{\sim}.000$). Conclusion: From the results stated above, it can be concluded that standardised intravenous injection control instruction for nurses brought out better evaluation, i.e. satisfaction, from the patients and their guardians, and the nurses who received the instruction showed better performances in intravenous injection control.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1502-1513
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• 2006

This study analyzes the design and part load performance of a power generation system combining a micro gas turbine (MGT) and an organic Rankine cycle (ORC). Design performances of cycles adopting several different organic fluids are analyzed and compared with performance of the steam based cycle. All of the organic fluids recover greater MGT exhaust heat than the steam cycle (much lower stack temperature), but their bottoming cycle efficiencies are lower. R123 provides higher combined cycle efficiency than steam does. The efficiencies of the combined cycle with organic fluids are maximized when the turbine exhaust heat of the MGT is fully recovered at the MGT recuperator, whereas the efficiency of the combined cycle with steam shows an almost reverse trend. Since organic fluids have much higher density than steam, they allow more compact systems. The efficiency of the combined cycle, based on a MGT with 30 percent efficiency, can reach almost 40 percent. hlso, the part load operation of the combined system is analyzed. Two representative power control methods are considered and their performances are compared. The variable speed control of the MGT exhibits far better combined cycle part load efficiency than the fuel only control despite slightly lower bottoming cycle performance.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.15-15
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• 2003

We provide some recent results of approximation algorithms for solving Markov Games and discuss their applications to problems that arise in Computer Science. We consider a receding horizon approach as an approximate solution to two-person zero-sum Markov games with an infinite horizon discounted cost criterion. We present error bounds from the optimal equilibrium value of the game when both players take “correlated” receding horizon policies that are based on exact or approximate solutions of receding finite horizon subgames. Motivated by the worst-case optimal control of queueing systems by Altman, we then analyze error bounds when the minimizer plays the (approximate) receding horizon control and the maximizer plays the worst case policy. We give two heuristic examples of the approximate receding horizon control. We extend “parallel rollout” and “hindsight optimization” into the Markov game setting within the framework of the approximate receding horizon approach and analyze their performances. From the parallel rollout approach, the minimizing player seeks to combine dynamically multiple heuristic policies in a set to improve the performances of all of the heuristic policies simultaneously under the guess that the maximizing player has chosen a fixed worst-case policy. Given $\varepsilon$>0, we give the value of the receding horizon which guarantees that the parallel rollout policy with the horizon played by the minimizer “dominates” any heuristic policy in the set by $\varepsilon$, From the hindsight optimization approach, the minimizing player makes a decision based on his expected optimal hindsight performance over a finite horizon. We finally discuss practical implementations of the receding horizon approaches via simulation and applications.