• Journal of KSNVE
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• v.7 no.5
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• pp.811-817
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• 1997

This paper is concerned with the active vibration controller design for the grid structure based on the positive position feedback (PPF) and the strain rate feedback (SRF) control. A new control methodology by the combination of the PPF and SRF control can suppress all the modes of the structure theoretically and can be easily implemented with analog circuits. The underlying concept for the design of the new controller is that the SRF controller stabilizes the modes higher than the second mode and the PPF controller stabilizes the fundamental mode which is destabilized by the SRF controller. In order for the new controller to be implemented succesfully, the collocated control is necessary. To this end, the piezoceramic sensor and actuator are located as close as possible, thus realizing the nearly collocated control. The combined PPF and ARF controller proves its effectiveness by experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.400-406
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• 1997

This paper is concerned with the active vibration control of grid structure by means of piezoceramic actuators and sensors. The control technique used in this paper is based on the positive position feedback(PPF) and the strain rate feedback(SRF) control, which have been successfully used for the vibration control of beam structures. A new control methodology is developed using the PPF and SRF controller of single-input single-output method. The PPF controller is used for the suppression of first bending mode and SRF controller is used for the suppression of higher vibration modes of grid structure. Electric circuits for the realization of control schemes are explained in detail. The control techniques prove its effectiveness by experiments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.407-412
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• 1997

There has been a recent surge of research interest on the smart structure. This paper presents active vibration control scheme of multi-mode forced vibration using piezoceramic sensors/actuators. The control scheme adopted is the Positive Position Feedback control. Among various vibration control techniques, PPF control technique makes use of generalized displacement measurements to accomplish vibration suppression. Two independent controllers are implemented to control the first and the second modes of the beam under external excitation. Experimental results for various damping ratio and feedback gains of the PPF controllers are compared with respect to the control efficiency. The results indicate that steady state vibration under wideband excitation can be controlled effectively when multiple sets of PZT sensors/actuators were used with PPF control technique.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.4
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• pp.383-392
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• 2012

This paper reports the active vibration control of plates using a positive position feedback(PPF) controller with moment pair actuators. The equations of motion of the plates under a force and moment pairs are derived and the equations of PPF controllers are formulated. The numerical active control system is then achieved. The effect of the parameters - gain and damping ratio - of the PPF controllers on the open loop transfer function was investigated mainly in terms of the system stability. Increasing the gain of the PPF controller tuned at a mode, the magnitude of the open loop transfer function is increased at all frequencies without changing the phase behavior. The increase of the damping ratio of the PPF controller leads to decrease the magnitude of the open loop transfer function and to modify its phase characteristics, ie, system stability. Based on the behavior of the gain and the damping ratio of the controller, PPF controller for reduction of the plate vibration can be achieved. Two PPF controllers are designed with their connection in parallel to control the two modes simultaneously. Each PPF controller is tuned at the $1^{st}$ and $2^{nd}$ modes, respectively. Their parameters were determined to remain the system to be stable based on the results of the parametric study. A significant reduction in vibration at the tuned modes can be obtained.

• Korean System Dynamics Review
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• v.11 no.2
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• pp.77-102
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• 2010

This paper examines a mechanism of the Electronic Territory Expansion and the Information-oriented Society. Especially, a strategy for the territory development based on intelligence is suggested. The strategy is divided into a strategy for the domestic electronic territory and a plan for the global electronic territory. To examine the strategy and the plan, this paper is using the causal map analysis based on the System Thinking Approach. The causal map of the mechanism is characterized by a positive feedback loop. The paper has concluded that it is important to make the positive loops as a virtuous circle. It means that when a society dominates the advantageous position firstly in the field of intelligent and electronic territory, the competitiveness can grow in arithmetical progression.

• The Korean Journal of Emergency Medical Services
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• v.15 no.2
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• pp.101-108
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• 2011

Purpose: Cardiopulmonary resuscitation (CPR) prevents tissue necrosis of the brain and cardiac muscle in the cardiac arrest patient and requires exact skills in order to increase survival rate. Through comparison of the training effects of feedback manikin and non-feedback manikin, this study present the effective CPR device to CPR instructors. Method: This CPR course for 80 students by using Resusci Anne $SkillReporter^{TM}$ (RASR; Laerdal Medical, Stavanger, Norway) and Actar 911 $Squadron^{TM}$ (A911; Vital Signs, New Jersey, USA) held on December 22, 2009. Thirty seven students and two assistants were placed in one laboratory, there were five RASR manikins which provide the LED performance indicator, not the metronome. Forty two students and two assistants were placed in the other laboratory, there were 20 A911 manikins which don't provide any feedback indicator. Chest compression scores and ventilation compression scores obtaining from two groups were analysed statistically by using independent t-test. Results: Chest compression scores, average depth (mm) was 37.5 in RASR and 41.80 A911 (p=.004), too depth (#) was 2.8 in RASR and 19.4 A911 (p=.005), average number per min (#/min) was 64.4 in RASR and 68.2 A911 (p=.038), wrong hand position (#/min) was 10.9 in RASR and 30.8 A911 (p=.040). Four items that showed better scores in group RASR had statistically significant difference. Ventilation compression scores, percent correct (%) was 40.6 in RASR and 20.6 A911 (p<.001), number correct (#) was 4.7 in RASR and 2.1 A911 (p=.002), too fast (#) was 0.9 in RASR and 2.9 A911 (p=.003), average volume (ml) was 536.5 in RASR and 707.1 A911 (p=.011). Also, three items that showed better scores in group RASR had statistically significant difference. Conclusions: Regarding the positive effect of CPR training feedback, comparison between the real-time visual feedback manikin (RASR) and the non-feedback manikin (A911) showed that RASR had better results than A911 in chest compression except average number per min (it means that we need harder chest manikin) and ventilation. Verification of the training effect in the real world such as CPR outcomes is also necessary. A proper application of manikin in training circumstances and research on retention of CPR skills will be needed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.324-329
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• 2010

Vibrations caused by automobile engine are absorbed mostly by a passive-type engine mount. However, user specifications for automobile vibrations require more stringent conditions and higher standard. Hence, active-type engine mount have been developed to cope with such specifications. The active-type engine mount consists of sensor, actuator and controller where a control algorithm is implemented. The performance of the active engine mount depends on the control algorithm if the sensor and actuator satisfies the specification. The control algorithm should be able to suppress persistent vibrations caused by the engine which are related to engine revolution. In this study, three control algorithms are considered for suppressing persistent vibrations, which are the positive position feedback control algorithm, the strain-rate feedback control algorithm, and the modified higher harmonic control algorithm. Experimental results show that all the control algorithms considered in this study are effective in suppressing resonant vibrations but the modified higher harmonic controller is the most effective controller for non-resonant vibrations.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1176-1182
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• 2010

Vibrations caused by automobile engine are absorbed mostly by a passive-type engine mount. However, user specifications for automobile vibrations require more stringent conditions and higher standard. Hence, active-type engine mount have been developed to cope with such specifications. The active-type engine mount consists of sensor, actuator and controller where a control algorithm is implemented. The performance of the active engine mount depends on the control algorithm if the sensor and actuator satisfies the specification. The control algorithm should be able to suppress persistent vibrations caused by the engine which are related to engine revolution. In this study, three control algorithms are considered for suppressing persistent vibrations, which are the positive position feedback control algorithm, the strain-rate feedback control algorithm, and the modified higher harmonic control algorithm. Experimental results show that all the control algorithms considered in this study are effective in suppressing resonant vibrations but the modified higher harmonic controller is the most effective controller for non-resonant vibrations.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.8
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• pp.612-618
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• 2003

A hybrid vibration control scheme using ER fluid and PZT patches is proposed. Dynamic characteristics of the beam embedded with the ER fluid can be controled by changing the strength of the electric field applied on the ER fluid, thus provides a mean to avoid the resonance. It was found that active vibration control of the structure embedded with ER fluid failed to suppress the vibration excited with broad band frequency due to the limited change of the dynamic characteristics of the structure. To compensate this limited effect of the control scheme with ER fluid alone, PPF control using PZT patches as sensors and actuators is added to construct a hybrid controller. Experimental results suggests that proposed hybrid controller is effective to suppress the additional resonance vibration that appears when each controller is used alone.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.727-730
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• 2007

Coil inductor has been used widely as an electromagnet, because of the high magnetic filed resulting from the voltage applied to the coil. In this study the coils were used in vibration suppression as an actuator. The control system consists of a coil attached in aluminum beam and a permanent magnet set at its bottom. This actuation method is easy to be incorporated into the system and allows significant forces to be applied without contacting with the structure. Three types of coils (cylindrical type, square type, Circular sheet type) were employed in vibration suppression of cantilever beam. The positive position feedback (PPF) controller was applied to the magnet-coil actuator to suppress the first mode of vibration. Experimental results showed that the cylindrical type and square type coil made good vibration suppression efficiency under PPF controller than their eddy current damper. However, there was minimal difference for the circular sheet type coil if compared with its eddy current damper.