• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.232-237
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• 1991

Digital Variable Structure Controller(DVSC) is proposed to control variable speed recirculating pump for hot-water heating control system. In this study, nonlinear sliding line is used beyond output error boundary layer and PID sliding line is used within the layer. For long dead time compensation, constraint is added to Smith predictor algorithm. Steady state error is eliminated by using the proposed sliding line in spite of heating load change. By decreasing sampling time, good sliding motion is yielded but system output noise bv flow dynamics is amplified.

• Solar Energy
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• v.19 no.3
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• pp.13-21
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• 1999

Calculation method about the water temperature variable inside hot water pipe had proposed in the past does not correspond with branch pipe system, variable of water volume, variable of entrance water temperature, using and so on. A calculation method proposed in this paper can solve above problems, and calculate the kinds variation of the water temperature inside pipe in the real use state of the hot water pipe.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.12
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• pp.1586-1593
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• 1988

A new control scheme for the variable-structure control system using new time-varying switching variable is presented in this paper. It is proposed to have new algorithm for reducing the reaching time on a switching hyperplane by modifying the Morgan's algorithm. From the results of the simulation, it is concluded the proposed control algorithm yields smaller control inputs (without disturbance) and ripples (with disturbance) than that obtained by Morgan's algorithm in the steady-state. This control algorithm can be applied to proper control systems having sensitive effects on disturbances, due to the robustness.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.213-220
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• 1989

This paper describes the application of the variable structure control(VSC) concept for the position control of an electro-hydraulic servomotor system. The basic philosopy of VSC is that the structure of the feedback control is altered as the state crosses discontinuity surfaces in the state space with the result that certain desirable properties are achieved. The switching of the control function yields total(or selective) invariance to system parameter variations and disturbances, and closed loop eigen value placement in time-varing and uncertain systems. The control scheme is derived, implemented and tested in the laboratory where analog controller have been used to control the representive servosystem. The control system schematics are given and simple results are shown for illustration. And the results of variable structure system for the electro-hydraulic servomotor were compared to that of the fixed structure system when load disturbance and system parameter variation exists.

• Health Policy and Management
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• v.14 no.3
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• pp.66-96
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• 2004

This study was intended to describe the hypertensive patient's lifestyle and quality of life by creating a hypothetic model on the lifestyle and quality of life and by examining a causeand effect relationship, and to contribute to countermeasures for practicing their lifestyle and improving the quality of life through creating a predictable model. Exogenous variable($\xi$) of hypothetic model in this study composed of a family support, hypertension knowledge, perceived benefit and toughness. Endogenous variable($\eta$) composed of self-esteem, perceived health state, depression, lifestyle and quality of life. There were 6 measured variables for exogenous variable(x). There were 9 measured variables(y) for endogenous variable. Also, there was error variable ($\delta,\;\epsilon$) of an individual. The survey was conducted for 207 hypertensive parents who received an out-patient service for 3 weeks from September 15, 2003 to October 3, 2003 after diagnosing as hypertension from 2 general hospitals in Daegu. As the conformance of hypothetic model in this study, there were $x^2$= 155.81, standard $x^2$ ($x^2$/df)=2.32, GFI=0.003, NFI=0.971, CFI=0.982, and RMSEA=0.080. Generally, the hypothetic model and actual data were well coincided. The higher the hypertension knowledge was(t=6.030), the higher the perceived benefit was(t=9.429), the higher the toughness was(t=2.783), and the higher the perceived health state was(t=2.282), the higher the lifestyle was. However, the degree of depression (t=-0.038), family support(t=1.161), and self-esteem(t=0.518) was not affected. The higher the family support was(t=10.476), the higher the self-esteem was(t=7.244), the higher the perceived health state was(t=6.996), the lower the degree of depression was(t=-2.044), and the higher the practice degree of lifestyle was(t=3.315), the higher the quality of life was. However, the toughness(t=1.672) didn't have a significant influence on the quality of life. It was modified to increase the model conformance and gain a conscious model As the result of model revision, for the model conformance, there were $x^2$= 118.43, standard $x^2$=1.69, GFI=0.923, NFI=0.976, CFI=0.982, and RMSEA=0.078. As the revised model showed the better conformance than hypothetic model, it seemed to be more suitable model. In the revised model, the perceived benefit(t=9.440) affected the lifestyle in the revised model. Then, the lifestyle was influenced by hypertension knowledge(t=6.139), toughness (t=2.757), family support(t=2.078), perceived health state(t=1.962) in the order. As a factor which affected the quality of life, there were the family support(t=l0.46l), self-esteem(t=7.368), perceived health state(t=6.989), lifestyle(t=3.316), toughness(t=2.584), and depression(t=-1.968) in the order. It showed the significant effect.

• Journal of Korean Academy of Nursing
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• v.9 no.1
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• pp.9-22
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• 1979

The major purpose of this study was to compare the state anxiety of surgical patients by sex (male/female), area of operation (sex-organ/non sex-organ), and family planning (having the plan of child-bearing/having no plan of child-bearing). One hundred sixty patients who were to get surgical operation were equally divided into eight groups resulted from combination of variables of sex, area of operation, and family planning, The state anxiety of surgical patients was measured in terms of the discrepancy score between the state anxiety score on the State-Trait Anxiety Inventory (STAI) administered at a day before operation and the trait anxiety score on it which was administered at a day before discharge. In order to test statistically the differences among meant scores of the state anxiety obtained by eight groups, multiple comparisons were carried out by Scheffe method. The results of this study led to the conclusions that, (1) there was no significant sex difference in the state anxiety of surgical patients, when the area of operation and the family planning variables were disregarded, (2) the state anxiety of patients who were to get operation of their sex-organ was significantly higher than that of patients who were to get operation on the parts other than their sex-organ, when variables of the sex and the family planning were not taken into account, (3) there was no significant sex difference in the state anxiety of patients who were to Bet operation on the parts other than their sex-organ, when the family planning variable was disregarded, (4) the state anxiety of female patients who were to get operation on their sex-organ was significantly higher than the stale anxiety of male patients who were to get operation on their sex-organ, when the family planning variable was not taken into account.

• The Korean Journal of Food & Health Convergence
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• v.7 no.3
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• pp.13-23
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• 2021

The purpose of this study was to explain the influence of motivation, leadership, and discipline on the performance of the midwife at Sharia Hospital X in Central Java Indonesia before the Covid-19 pandemic. This research is a combination between quantitative research and qualitative research (mix method). The population in this study were all midwives sharia hospital x in central java Indonesia, totaling 75 people. The primary data in this study came from questionnaires, interviews, observation, and documentation, then from the results of the analysis and data processing the researcher interpreted it more deeply using qualitative methods. The results of this study conclude that motivation, leadership, and discipline are proven to have a positive and significant effect on the performance of midwives, thus it can be concluded that an increase in motivation, leadership, and discipline in work will be able to improve the performance of the midwifes Sharia Hospital X. These results give an understanding that every time there is an increase in motivation, leadership, and work discipline, it will increase the performance of the midwifes. Motivation is the biggest variable affecting the performance, leadership is the second and work discipline is the smallest variable that affects the performance of midwives.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.293-296
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• 1997

Robust stability conditions for discrete-time variable structure control is proposed. Conventionally the discrete-time variable structure control method with a variable structure uncertainty compensator approach requires a bounded changing rate of the uncertainties to ensure robust stability. However, when uncertainties vary as a function of state variables, which occur with parametric uncertainties, it is not reasonable to assume a bounded variation on the uncertainties. In this paper, uncertainties are assumed to consist of exogenous disturbances and parametric uncertainties. An uncertainty compensator is used to deal with the former, and a robust stability condition is derived using Small Gain Theorem for the latter.

• Proceedings of the Korean Magnestics Society Conference
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• 2005.12a
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• pp.8-9
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• 2005

• Kyungpook Mathematical Journal
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• v.55 no.4
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• pp.779-806
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• 2015

We construct a state model for the two-variable Kauman polynomial using planar trivalent graphs. We also use this model to obtain a polynomial invariant for a certain type of trivalent graphs embedded in $\mathbb{R}^3$.