• International journal of advanced smart convergence
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• v.5 no.1
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• pp.34-46
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• 2016

Networked Control System (NCS) has evolved in the past decade through the advances in communication technology. The problems involved in NCS are broadly classified into two categories namely network issues due to network and control performance due to system network. The network problems are related to bandwidth allocation, scheduling and network security, and the control problems deal with stability analysis and delay compensation. Various delays with variable length occur due to sharing a common network medium. Though most delays are very less and mostly neglected, the network induced delay is significant. It occurs when sensors, actuators, and controllers exchange data packet across the communication network. Networked induced delay arises from sensor to controller and controller to actuator. This paper presents an adaptive delay compensation process for efficient control. Though Smith predictor has been commonly used as dead time compensators, it is not adaptive to match with the stochastic behavior of network characteristics. Time delay adaptive compensation gives an effective control to solve dead time, and creates a virtual environment using the plant model and computed delay which is used to compensate the effect of delay. This approach is simulated using TrueTime simulator that is a Matlab Simulink based simulator facilitates co-simulation of controller task execution in real-time kernels, network transmissions and continuous plant dynamics for NCS. The simulation result is analyzed, and it is confirmed that this control provides good performance.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.9
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• pp.997-1005
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• 1990

Integral Error and State Feedback (IESF) controller which incorporates state feedback as a modern control scheme and integral action as a classical control scheme has better performance than that of conventional PID controller in linear time invariant system. But the structure of the IESF controller requires all the state variables of the system and is applicable only to pole assignable linear time invariant systems without time delay. Many industrial processes have large time delay and it is impossible to directly apply IESF control scheme to those processes. In this paper, a new controller structure, Modified Integral Error and State Feedback (MIESF) has been suggested in order to effectively control processes having time delay and its performance has been analyzed and its effectiveness has also been confirmed. As the proposed controller uses output feedback scheme based on integral error and state feedback (IESF) method, it can be simply designed by pole assignment algorithm irrespective of the order of the process. The MIESF controller can follow setpoint changes without overshoot. It is robuster than conventional Smith-Predictor plus PI(D) controller in case of occurring time delay mismatch and extra parameter mismatches between the process and the model. It can enhance control performance by intentional time delay mismatch.

• Women's Health Nursing
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• v.11 no.2
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• pp.156-162
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• 2005

Purpose: The study was done to identify the relationship of symptoms of stress, cancer prevention behavior, the quality of life in women, and the factors influencing the quality of life. Method: The subjects of this study were 210 married women. They were living in Gyeonggi Province and Busan Metropolitan City. Symptoms of stress were measured by the Park's Stress Scale. Cancer preventive behavior was measured by Suh's Korean scale, and Smith Kline Beecham Quality of life' Scale by Dunbar. Data was analyzed with the SPSS program by ANOVA, Pearson's correlation, and Multiple Regression Analysis. Result: The higher scores of physical stress correlated with lower practice scores of cancer prevention behavior. Psychological and physical stress revealed negative correlations among sub-items of the QOL such as competence, psychological well-being, stability, physical well-being and activity. Multiple regression analysis revealed that the predictor of quality of life in the women was stress. A combination of symptoms of stress and cancer prevention behaviors accounted for 35.3% of the variance in the quality of life in the women. Conclusion: The most important factor influencing the quality of life of women was stress. Thus the study's findings can be useful in directing a comprehensive nursing care plan to improve the QOL of women.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.33-39
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• 2007

LonWorks over IP (LonWorks/IP) virtual device network (VDN) is an integrated form of LonWorks device network and IP data network. LonWorks/IP VDN can offer ubiquitous access to the information on the factory floor and make it possible for the predictive and preventive maintenance on the factory floor. Timely response is inevitable for predictive and preventive maintenance on the factory floor under the real-time distributed control. The network induced uncertain time delay deteriorates the performance and stability of the real-time distributed control system on LonWorks/IP virtual device network. Therefore, in order to guarantee the stability and to improve the performance of the networked distributed control system the time-varying uncertain time delay needs to be compensated for. In this paper, under the real-time distributed control on LonWorks/IP VDN with uncertain time delay, a control scheme based on disturbance observer and ZPETC(Zero Phase Error Tracking Controller) phase lag compensator is proposed and tested through computer simulation. The result of the proposed control is compared with that of internal model controller (IMC) based on Smith predictor and disturbance observer. It is shown that the proposed control scheme is disturbance and noise tolerant and can significantly improve the stability and the tracking performance of the periodic reference. Therefore, the proposed control scheme is well suited for the distributed servo control for predictive maintenance on LonWorks/IP-based virtual device network with time-varying delay.

• Journal of Korean Academy of Nursing Administration
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• v.11 no.1
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• pp.1-12
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• 2005

Purpose: The purpose was to analyze the effects of internal marketing activity factors on nurse's turnover intention, nursing task performance and nursing productivity. Methods: The subjects were 355 nurses who were working at the 3 universities hospital over 1 year. The instruments were used of internal marketing activity factors(Lee, 2001), turnover intension(Lee, 1995), nursing task performance(Park, 1988) and nursing productivity(McNeese-Smith, 1996). Results: The mean score of internal marketing activity factors was 2.79, education and training 2.97, individualization 2.93, communication 2.87, promotion 2.76, work environment 2.63, reward system 2.62, and management vision for employee 2.61. The turnover intention was 3.12, nursing task performance 3.49, and nursing productivity 3.38. The internal marketing activity factors were negatively correlated with turnover intention(r=-0.37, p<0.0001), and positively correlated with nursing task performance(r=0.29, p<0.0001) and nursing productivity(r=0.30, p<0.0001). The key predictor of turnover intension was reward system, education and training, communication, and salary. They explained 35.0% of the total variance. In nursing task performance, communication, management vision for employee, salary and unit explained 26.0% of the total variance. In nursing productivity, communication, reward, education and training, salary, and position explained 24.0%. Conclusions: To increase nurse's nursing task performance and nursing productivity and to decrease turnover intention, it is necessary to concentrate on improving communication and reward system in the internal marketing activity factors. Through these activities, the effectiveness of internal marketing strategies will be enhanced and finally, nursing organizational outcome will be increased.