• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.44-47
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• 1996

Bang-bang control law provides the optimal solution for a minimum-time control problem, but ignores the intermediate path except for the initial and final points. In this paper, a near minimum-time suboptimal fuzzy logic controller is introduced that can control the intermediate path. A dynamic model for a system is established using the average dynamics method of linearization. System model is continuously updated over the control time periods. This makes it suitable for high speed or variable payload applications. Bang-bang control theory is modified and used to derive the preliminary control law. A fuzzy logic algorithm is then applied to adjust and find the best solution. The solution will provide the suboptimal minimum-time control law which can avoid obstacles in the workspace.

• Structural Engineering and Mechanics
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• v.25 no.5
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• pp.541-564
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• 2007

• Journal of the Korean Society for Precision Engineering
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• v.26 no.5
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• pp.120-127
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• 2009

An electric furnace, inside which desired temperatures are kept constant by generating heat, is known to be a difficult system to control and model exactly because system parameters and response delay time vary as the temperature and position are changed. In this study the heating system of ceramic drying furnaces with time-varying parameters is mathematically modeled as a second order system and control parameters are estimated by using a RIV (Recursive Instrumental-Variable) method. A modified bang-bang control with magnitude tuning is proposed in the time optimal temperature control of ceramic drying electric furnaces and its performance is experimentally verified. It is proven that temperature tracking of adaptive time optimal control using a second order model is more stable than the GPCEW (Generalized Predictive Control with Exponential Weight) and rapidly settles down by pre-estimation of the system parameters.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.10
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• pp.671-677
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• 2004

This paper presents the design of a now controller for the read/write head of a hard disk drive. The general controller for seeking is the time-optimal control. However if we use only the time optimal control law, this could be vulnerable to chattering effect. To solve this problem, we propose a modified controller design algorithm in this paper. The proposed controller consists of bang-bang control for seeking and sliding-mode control for tracking. Moreover, to test the robustness and stability of control system, a bounded disturbance is selected to maximize a severity index. Simulation results show the superiority of the proposed controller through comparison with time optimal VSC(variable structure control).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.282-286
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• 2000

In this paper, magneto-rheological(MR) damper is studied for vibration control of large infra structures under earthquake. Generally, active control devices need a large control force and a high power supply system to reduce the vibration effectively. Large and miss tuned control force may induce the dangerous situation such that the generated large control force acts to amplify the structural vibration. Recently, to overcome the weaknesses of the active control, the semi-active control method is suggested by many researchers. Semi-active control uses the passive control device of which the characteristics can be modified. Control force of the semi-active device is not generated from the actuator with power supply. It is generated as a dynamic reaction force of the device same as in the passive control case, so the control system is inherently stable and robust. Unlike the case of passive control, control force of semi-active control is adjusted depending on the measured response of the structure, so the vibration can be reduced more effectively against various unknown environmental loads. Magneto-rheological(MR) damper is one of the semi-active devices. Dynamic characteristics of the MR material can be changed by applying the magnetic fields. So the control of MR damper needs only small power. Response time of MR to the input voltage is very short, so the high performance control is possible. MR damper has a high force capacity so it is adequate to the vibration control of large infra structure. Because MR damper has a nonlinear property, normal control method used in active control may not be effective. Clipped optimal control, modified bang-bang control etc. have been suggested to MR damper by many researchers. In this study, sliding mode fuzzy control(SMFC) is applied to MR damper. Genetic algorithm is used for the controller tuning. To verify the applicability of MR damper and suggested algorithm, numerical simulation on the aseismic control is carried out. Simulation model is three-story building structure, which was used in the paper of Dyke, et al. The control performance is compared with clipped optimal control. The present results indicate that the SMFC algorithm can reduce the earthquake-induced vibration very effectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.9
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• pp.861-869
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• 2012

This paper presents a high performance position controller in a driving system using a time optimal control which is widely used to control driving systems to a desired reference position or velocity in minimum response time. The main purpose of this study is an improvement of transient response performance rather than steady-state response comparing with another various control strategies. In order to improve the performance of time optimal control, we tried to find the cause of the steady-state error in the driving system we have already made up and also suggest the newly modified type of time optimal control method in this paper.

• Journal of IKEEE
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• v.17 no.4
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• pp.544-549
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• 2013

This paper describes a modified binary phase detector (Bang-Bang phase detector - BBPD) for jitter reduction in clock and data recovery (CDR) circuits. The proposed PD reduces ripples in the VCO control voltage resulting in reduced jitter for CDR circuits. A 2.5 Gbps CDR circuit with a proposed BBPD has been designed and verified using Dongbu $0.13{\mu}m$ CMOS technology. Simulation shows the CDR with proposed PD recovers data with peak-to-peak jitter of 10.96ps, rms jitter of 0.86ps, and consumes 16.9mW.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.93-102
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• 2006

Control input's saturation of active control devices for large structures under large external disturbances are often occurred. It is more difficult to obtain the exact values of mass and stiffness as structures are higher. The modelling errors between mathematical models and real structures must be also included as parameter uncertainties. Therefore, in active vibration control of civil engineering structures like buildings and bridges, the robust saturation controller design method considering both control input's saturation and parameter uncertainties of system is needed. In this paper, stabilities of linear optimal controller LQR, modified bang-bang controller, saturated sliding mode controller, and robust saturation controller among various controllers which have been studied and applied to active vibration control of buildings are investigated. Especially, unstable phenomena of the LQR, the modified bang-bang controller and the saturated sliding mode controller when the control input is saturated or parameter uncertainties exist are presented to show the necessity of the robust saturation controller. The robust stability of the robust saturation controller are shown through a numerical example of a 2DOF linear vibrating system and an experimental test of the two-story structure with an active mass damper (AMD).

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.24 no.2
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• pp.16-27
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• 2011

Objective : To investigate the effects of Pyeongwi-san-gamibang on atopic dermatitis, this study measured TEWL(transepidermal water loss), observed scratching behaviors and checked levels of Total IgE, IL-4, IFN-${\gamma}$ and conducted skin biopsy on NC/Nga mice with atopic dermatitis. Methods : NC/Nga mice were challenged with DNCB during 5 weeks to develop atopic dermatitis-like skin lesions. The NC/Nga mice with atopic dermatitis were divided into three groups of control group, PW-d, PW-e group. Once a day for 22 days, Pyeongwi-san-GamiBang extract with water was administered for the PW-d group and the extract with 80% ethanol was administered for PW-e group compared with saline solution for control group. During drug administration, sensitization by DNCB had lasted for three times per week. Results : 1. TEWL had no statistical difference among 3 groups. 2. The scratching behaviors had no statistical difference among 3 groups. 3. The levels of Total IgE in PW-d, PW-e group had a statistically significantly higher than that of the control group although difference between the control group and the PW-d, PW-e group were similar. 4. The level of IL-4 had no statistical difference among 3 groups. 5. The level of IFN-${\gamma}$ had no statistical difference among 3 groups. 6. As the observation of toluidine blue stained lesion, both PW-d and PW-e group had lower level of histamine releasement compared with the control group. Conclusion : Result based on these experiments, Pyeongwi-san-GamiBang on atopic dermatitis-like skin inflammation in NC/Nga mice is not effective. But, as the study showed significantly individual differece, we need to repeat these study after supplementing the object number and modified indicator of clinical severity.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.22-24
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• 1996

Small size DC motor control method for portable drug delivery system has been developed to be used for the actuator of insulins pump. The control method gives the controllabilities both in high speed(40-50 revolution per second(rps)) DC motor drive and also in low speed(0.5-1rps). In low speed mode DC motor is controlled to act like stepping motor and in high speed to optimize power consumption. To control both mode modified bang bang control is suggested. Using this method small size DC motor(spec.) speed is controlled from 0.2 rps to 50 rps. Experimental setup is developed using micro-processor(PIC16C73, Micro Chips co., USA), motor turns checking circuitry, small size DC motor for pager(SM1012, Samhong co., Korea) and gear box. Results from experiment meet need for vailable load condition which is require for portable drug delivery system.