• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1573-1581
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• 1996

This paper present as experimental demonstratio of DSP and a sensory actuator that is used to actively control sound transmission/radiation through a vibrating plate. A plane acoustic wave incident on a clamped, thin circular plate was used as a noise source, and a sensory actuator bounded to the plate was used to control and sense vibration of the plate. The sound transmission reduction problem was tranformed as a structural vibration control problem that actively control the structural vibration modes coupled to acoustic modes. The results show that the first structural vibration mode is controlled with a reduction of 78 percent in the displacement and velocity of the plate. This corresponds to a 13dB reduction in the acoustic response. These experimental results indicate that a sensory actuator bounded to the plate can be employed to attenuate the sound transmitted to radiated from the plate.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.734-739
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• 2003

Many types of smart materials and control laws are available to actively adjust the structure from various external disturbances. Usually, a certain type of control laws to activate a specific smart material is well established, but the effectiveness of the control scheme is limited by the choice of the smart materials and the responses of the structure. ER fluid is adequate to provide relatively large control force, on the other hand, the PZT patches are suitable to provide small but arbitrary control forces at any point along the structure. It was found that active vibration control mechanism using ER fluid failed to suppress the excitation off the resonant frequency with changed structural characteristics along the frequency response function of the closed loop of the control system. To compensate this additional peak of the closed loop system, PPF control using PZT as an actuator is added to construct a hybrid controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.446-451
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• 2003

This paper presents some examples of active control of flow-induced vibration using piezoelectric actuators. The flutter phenomenon, which is the dynamic instability of structure due to mutual interaction among inertia, stiffness, and aerodynamic forces, may cause catastrophic structural failure, and therefore the active flutter suppression is one of the main objectives of the aeroelastic control. Active flutter control has been numerically and experimentally studied for swept-back lifting surfaces using piezoelectric actuation. A finite element method, a panel aerodynamic method, and the minimum state space realization are involved in the development of the governing equation, which is efficiently used for the analysis of the system and design of control laws with modern control framework. The active control suppressed flow-induced vibrations and extended the flutter speed around by 10%. Another representative flow-induced vibration phenomenon is the oscillation of blunt bodies due to the vortex shedding. In general, it is quite difficult to set up the numerical model because of the strong non-linearity of the vortex shedding structure. Therefore, we applied adaptive positive position feedback controller, which requires no pre-determined model of the plant, and successfully suppressed the flow-induced vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.353-354
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• 2014

An active vibration control technique of a time-varying cantilever beam is proposed in this study. A simple in-house coil sensor instead of expensive commercial sensors was used to measure the vibrational displacement of the beam. Active band pass filters and artificial neutral net works detect the frequencies, amplitudes, and phases of the main vibration mode. The time constants of the low pass filter representing the positive position feedback controller are updated in real-time, which generates the control voltage input to actuate the piezoelectric actuator and suppress the vibration. An experiment was successfully performed to verify the algorithm for a cantilever beam, which fundamental natural frequency arbitrarily varies between 9 Hz ~ 18 Hz. The present active vibration suppression technique can be applied to variety of structures which undergoes large variation of dynamic characteristics while operating.

• Journal of Home Health Care Nursing
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• v.24 no.3
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• pp.306-315
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• 2017

Purpose: This study was conducted to examine psychological empowerment and awareness and performance of Healthcare-Associated Infections(HAIs) control among Intensive Care Unit (ICU) nurses. Method: The data for this study were collected using structured questionnaires from 178 nurses working in the ICUs of four hospitals with more than 500 beds. Results: The subjects'psychological empowerment, awareness and performance of HAIs control were mean over. The subjects'psychological empowerment showed statistically significant differences depending on age, marital status, academic background, clinical career, ICU career, and position and experience in infection control among their general characteristics. Awareness of HAIs control showed statistically significant differences depending on age, gender, marital status, clinical career, and ICU career. Performance showed statistically significant differences depending on age, gender, marital status, and, ICU career. Regarding the subjects' performance of HAIs control, there was a statistically significant positive correlation between psychological empowerment and awareness. Conclusion: It was found that it is necessary to strengthen differential customized training according to the subjects'characteristics for effective HAIs control, and to strengthen the nurses'awareness of HAIs control through systematic evaluation, monitoring, and feedback, as well as continuous education and training.

• The Journal of the Korea Contents Association
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• v.13 no.2
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• pp.235-243
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• 2013

This study analyzes the interaction of variables consisting of the local finance system based on the theory of system thinking regarding how financial decentralization can be understood as the political means for local decentralization and why it is needed. The results gained from this research are as follows: first, variables consisting of the local finance system form interactional relationship in the significant level, and it has been found that rapid growth and rapid decline repeat with five positive feedback loops as the center. Second, strategic points for the validity of local finance decentralization were discovered through causal map modeling. In particular, it has been shown that the virtuous cycle structure declines the local finance system through the constant operation of variables (government subsidies, taxation for real estate transactions, central government's local finance mediation system, and local government debt, etc.) that deteriorate the vicious cycle structure. Based on this, strategic policy tasks were drawn. It is expected that this study will help the understanding of the local finance system and increase academic width for local finance from the aspects of general knowledge, not the knowledge about local finance decentralization.

• Korea Journal of Hospital Management
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• v.8 no.3
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• pp.72-91
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• 2003

The purpose of this study is to investigate the recognition of health information managers, and to analyze the level of job satisfaction and organizational commitment of medical record technicians. The data for this study were collected through a self-administered survey with a structured questionnaire to 172 subjects from medical record technicians working in hospitals in Seoul and Gyeonggi Province as well as the faculty of medical schools across South Korea. In this analysis frequency, t-test, ANOVA, factor analysis and structural equation model were used. The main findings of this study are as follows: 1. As for recognition of the seven dimensions in the role of health information managers, the role as clinical data specialist received the most positive feedback, followed by document & repository managers, patient information coordinators, health information managers, data quality managers, security officers and research & decision support analyst. 2. The level of job satisfaction among medical information handlers and managers averaged 3.14. In terms of the factors in the work environment concerned with job satisfaction, being able to work independently and as team players reached the top among 6 factors with the average of 3.39, followed by professional position, salary & rewards, expectations for job performance and administration. 3. The average rate of organizational commitment stood at 3.09. Respondents tend to be focused on present tasks rather than future-oriented tasks. 4. The result of the analysis based on the relationship between recognition as health information managers, job satisfaction and organizational commitment found that all analysis are statistically meaningful. The more the respondents were aware of their roles as health information managers, the more they tended to be committed to their work and satisfied with their work. The more the respondents were committed to their work, the more satisfaction was seen. The effects of recognition as health information managers on organizational commitment measured 0.27 and for job satisfaction it was 0.17. The effects of organizational commitment on job satisfaction stood at 0.71. The feasibility of the model meets the standard at Chi-square value of 66.755 and the P value of 0.057. The Normed Fit Index (NFI) of 0.930 was in compliance with the standard for model feasibility and the squared multiple correlation coefficient of this model was 8% in organizational commitment and 60% in job satisfaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.284-290
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• 2020

This study was undertaken to determine the effects of SNAGs (sustained natural apophyseal glides) and visual convergence biofeedback on the proprioception and neck disability of patients with chronic neck dysfunction. A total of 31 patients with neck dysfunction were assigned to either SNAGs (n = 16) or biofeedback (n = 15). The groups were assessed for proprioception and neck disability, before and after the intervention. The SNAGs were performed using belt with flexion, extension and right-left rotation, whereas biofeedback training included visual feedback training with deep neck flexor. Intervention was implemented for 20 minutes, twice a week for 4 weeks. Biofeedback training a showed significant effect on the joint position sense (left and right rotation) as compared to the SNAGs group (p< 0.05), whereas neck disability index was significantly effective for SNAGs (p< 0.05). Ed. Notes: The previous statement lacked clarity. I have suggested the edit as per my understanding. Please review and revise appropriately, if required. Therefore, the SNAGs technique is effective for neck function, and biofeedback training is a positive intervention method for enhancing the proprioceptive sensation. In future studies on patients with neck pain, it may be possible to select an intervention method based on the characteristics of the disease.