• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1537-1541
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• 2003

In this paper, presented is a feedback control performance of vibratory gyroscope at various vacuum levels. Micro gyroscope, whose operation is based on the vibrating motion at the vacuum conditions, is highly influenced by the vacuum level of the operating circumstances. In general, we apply the feedback control scheme to the gyroscope in order to improve the performances of the sensor. And control performances of the gyroscope are related to those vacuum levels. So we need investigate the performances of the closed loop control at various vacuum conditions comparing with those of the open loop. The experimental results show that the sensitivity of the closed loop is less than that of the open loop especially in low vacuum conditions. Therefore, there should be trade-off between sensitivity and other sensor performances such as linearity, bandwidth when we apply feedback control to the gyroscope.

• Journal of the Korean Data and Information Science Society
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• v.17 no.3
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• pp.973-982
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• 2006

Performances of variable sampling interval(VSI) multivariate control charts with accumulate-combine approach for monitoring mean vector of p related quality variables were investigated. Shewhart control chart is also proposed to compare the performances of CUSUM and EWMA charts. Numerical comparisons show that performances of CUSUM and EWMA charts are more efficient than Shewhart chart for small or moderate shifts, and VSI chart is more efficient than fixed sampling interval(FSI) chart. We also found that performances of the CUSUM or EWMA chart with accumulate-combine approach are substantially efficient than those of Shewhart chart.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.407-412
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• 2009

In the present work, vibration control performance of active camera mount system for unmanned aero vehicle (UAV) is evaluated. An active mount featuring inertia type of piezostack actuator is designed and manufactured. Then, vibration control performances are experimentally evaluated. A camera mount system with four active mounts is constructed and mechanical model is established. The governing equation for the camera mount system is obtained and control model is constructed in state space model. Sliding mode controller which has inherent robustness to external disturbance is designed and implemented to the system. Vibration control performances are evaluated at each mount and center of gravity point. Effective vibration performances are obtained and presented in time and frequency domains.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1315-1321
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• 2009

In the present work, vibration control performance of active camera mount system for unmanned aero vehicle(UAV) is evaluated. An active mount featuring inertia type of piezostack actuator is designed and manufactured. Then, vibration control performances are experimentally evaluated. A camera mount system with four active mounts is constructed and mechanical model is established. The governing equation for the camera mount system is obtained and control model is constructed in state space model. Sliding mode controller which has inherent robustness to external disturbance is designed and implemented to the system. Vibration control performances are evaluated at each mount and center of gravity point. Effective vibration performances are obtained and presented in time and frequency domains.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.476-483
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• 2004

This paper presents a hybrid system combining lead rubber bearings and hydraulic actuators controlled by a μ-synthesis method for seismic response control of a cable-stayed bridge. A hybrid system could alleviate some of restrictions and limitations that exist when each system is acting alone because multiple control devices are operating. Therefore, the overall control performance of a hybrid system may be improved compared to each system, however the overall system robustness may be negatively impacted by active device in the hybrid system or active controller may cause instability due to small margins. Therefore, a f-synthesis method that guarantees the robust performance is considered to enhance the possibility of real applications of the control system. The control performances of the proposed control system are compared with those of passive, active, semiactive control systems and hybrid system controlled by LQG algorithm and an extensive robust analysis with respect to stiffness and mass matrices perturbation and time delay of actuator is performed. Numerical simulation results show that the control performance of the proposed control system is superior to that of the passive system and slightly better than that of the active and semiactive systems and two hybrid systems show similar control performances. Furthermore, the hybrid system controlled by a μ-synthesis method shows the good robustness without loss of control performances. Therefore, the proposed control system could effectively be used to seismically excited cable-stayed bridge which contains many uncertainties.

• Journal of the Korean Society of Radiology
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• v.11 no.2
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• pp.131-138
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• 2017

This study surveyed the medical staffs in Busan with regard to their awareness and to their performances of infection control in health care facilities. As a result of the survey, the level of awareness and performances showed a high scale regardless of the relation to infection control department, infection control guidelines, and infection control education in the health care facilities. Especially, the group educated on the infection control had shown a statistically significant result of 0.001 in the awareness and performances. The main reasons to failure on infection control practice resulted with a heavy workload and a lack of time. Moreover, it is concluded that the self-consciousness on the infection control have increased in reason that the 99.7% responded a need to infection control education. In general, level of the performance analyzed lower than the level of awareness and it seems that reforming such policy feasible is needed and being active in performing infection control individually is necessary in order to decrease the nosocomial infection.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.574-577
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• 2004

This paper presents a hybrid system combining lead rubber bearings and hydraulic actuators controlled by a $\mu-synthesis$ method for seismic response control of a cable-stayed bridge. A hybrid system could alleviate some of restrictions and limitations that exist when each system is acting alone because multiple control devices are operating. Therefore, the overall control performance of a hybrid system may be improved compared to each system, however the overall system robustness may be negatively impacted by active device in the hybrid system or active controller may cause instability due to small margins. Therefore, a $\mu-synthesis$ method that guarantees the robust performance is considered to enhance the possibility of real applications of the control system. The performances of the proposed control system are compared with those of passive, active, semiactive control systems and hybrid system controlled by a LQG algorithm. Furthermore, an extensive robust analysis with respect to stiffness and mass matrices perturbation and time delay of actuator is performed. Numerical simulation results show that the performances of the proposed control system are superior to those of passive system and slightly better than those of active and semiactive systems and two hybrid systems show similar control performances. Furthermore, the hybrid system controlled by a f-synthesis method shows the good robustness without loss of control performances. Therefore, the proposed control system could effectively be used to seismically excited cable-stayed bridge which contains many uncertainties.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.58-65
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• 1999

A magnetic levitation system requires a robustness to overcome a dynamic instability due to disturbances. In this paper a robust controller for a magnetically levitated fine manipulator is presented. The proposed controller consists of following two parts: a model reference controller and an $H_{\infty}$ controller. First, the model reference control stabilizes the motion of the manipulator. Then, the motion of the manipulator follows that of the reference model. Second, the $H_{\infty}$ control minimizes errors generated from the model reference control due to noise and disturbance since the $H_{\infty}$ control is a kind of robust control. The experiments of position control and tracking control are carried out by use of the proposed controller under the conditions of free disturbances and forced disturbances. Also, the experiments using PID controller are carried out under the same conditions. The results from above two controllers are compared to investigate the control performances. As the results, it is observed that the proposed controller has similar position accuracy but better tracking performances comparing to the PID controller as well as good disturbance rejection effect due to the robust characteristics of the controller. In conclusion. it is verified that the proposed controller has the simple control structure, the good tracking performances and good disturbance rejection effect due to the robust characteristics of the controller.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.5
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• pp.421-429
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• 2004

In Korea, the radiant heating system has been widely used as a residential heating method, which has been modernized to use hot water running into the tubes embedded in the floor structure. According to the recent improvement of living standard of residential buildings, the requirement of the thermal comfort and energy saving in heating system has been raised. Until now, the radiant floor heating system has been controlled by room thermostat installed in the living room, but for better thermal comfort, an individual room control method is adopted as an alternative. Therefore, it is necessary to evaluate the control performance between the current control method and the individual room control method. In this study, the control performance between the two systems is evaluated through the field experiment. And the control performances of room air temperature and energy performances are analyzed through the simulation using TRNSYS. Firstly, the simulations are performed in the various outdoor conditions and the flow rates and the simulation results are analyzed for the control performances. Also, to evaluate the energy performance, the simulations are performed under the operating conditions in which the set-point of the room air temperature is fixed or changed according to the schedule of occupancy, and the simulation results are analyzed between the two methods.

• Journal of Integrative Natural Science
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• v.12 no.3
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• pp.78-84
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• 2019

In many cases, the quality of a product is determined by several correlated quality variables. Control charts have been used for a long time widely to control the production process and to quickly detect the assignable causes that may produce any deterioration in the quality of a product. Numerical switching performances of multivariate cumulative sum control chart for simultaneous monitoring all components in the dispersion matrix ${\Sigma}$ under multivariate normal process $N_p({\underline{\mu}},{\Sigma})$ are considered. Numerical performances were evaluated for various shifts of the values of variances and/or correlation coefficients in ${\Sigma}$. Our computational results show that if one wants to quick detect the small shifts in a process, CUSUM control chart with small reference value k is more efficient than large k in terms of average run length (ARL), average time to signal (ATS), average number of switches (ANSW).