• Journal of Biosystems Engineering
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• 제23권5호
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• pp.427-438
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• 1998

In Korea, rotary implements are mainly utilized in the tillage operation. The attitude control system for rolling phenominon of tractors, which in caused due to uneven ground surfaces and sinkage of tractor wheels, is one of the most important control systems in agricultural tractors. The attitude control system of a rotary implement, attached on tractors, was designed and fabricated in this study. The control system was largely composed of four main units; a setting unit, a detection unit, a controller and a hydraulic unit. The implement was controlled by control signals from a computer proportional to controlled errors, on/off action of two directional solenoide valve and lift cylinder on the right lift rod. Response characteristic experiments for the control system fabricated in this study were carried out indoors and outdoors. The results of experiments showed the response characteristics sufficient to use as the attitude control system of rotary implements for agricultural tractors.

• 동력기계공학회지
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• 제6권3호
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• pp.71-77
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• 2002

In this study, a dynamic model of proportional pressure control valve using the bond graph and a predictive controller are presented in the form of dynamic matrix control which is concerned with a design method of digital controller for the electro hydraulic servo system. The bond graph can be utilized for all types of systems which involve power and energy, and it is applied to a propotional pressure control valve in this study. Recently, many researchers suggested that better control performance could be obtained by means of the predictive controls with future reference input, future control output and future control error. The Predictive controller is very practical because the controller can be easily applicable to a personal computer or a microprocessor. This study investigates through numerical simulations that hydraulic system with the predictive controller shows very good control performances.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.979-982
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• 2003

In this study, because of change in electromagnetic force, deformation of the free surface motion of a magnetic fluid is changed. Deformation of the free surface motion of a magnetic fluid for the change in electromagnetic force is discussed and carried out theoretically and experimentally on the basis of Rosensweig Ferrohydrodynamic Bernoulli Equation. Objective of this study explicates free surface motion by electromagnetic force and planes to designed controller. To control free surface of magnetic fluid, it embody designed two-dimensional free surface form of magnetic fluid. By using this characteristics, they applied to oscillator for surface control, flow control, boundary layer control. Strength of magnetic field and height of free surface of magnetic fluid measure as a hall-effect sensor. As performing height control of magnetic fluid, the result will be presented possibility of free surface deformation control.

• 수산해양기술연구
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• 제55권2호
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• pp.172-180
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• 2019

In this study, a ship motion control system design method is introduced for autonomous ships. Some related research results and technologies for autonomous ships have already been developed and applied to testing ships. Recently, the Norwegian Maritime Authority and the Coastal Administration have signed an agreement and started to test autonomous ships in the defined area. Considering recent technology trends and background, in this paper, the authors also try to develop autonomous ship control technologies. In the designed control system, an observer is introduced to estimate unmeasurable system states. Based on the servosystem with state estimator, ship motion control experiment is performed to evaluate control performance using a model ship in water basin.

• 한국수학교육학회지시리즈A:수학교육
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• 제56권4호
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• pp.435-452
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• 2017

The purpose of this study is to see correlation between parental psychological control and volition control in mathematics learning of 6th grade of elementary school. This study has carried out a survey for 371 male and female students in 6th grade of elementary school in Gyeongnam. We analyzed the collected data statistically, and the results are as follows. First, there was a significant difference in the level of volition control in mathematics learning between male and female students. The level of volition control in mathematics learning was found to be higher in female groups than in male groups. Second, there was no significant difference in father and mother's psychological control level perceived by 6th grade elementary school students. Third, there was a significant negative correlation between parental psychological control and their children's level of volition control in mathematics learning. In this study, by examining the correlation between parental psychological control and volition control level in mathematics learning of elementary school students, the higher the parental psychological control, the lower the level of volition control of their children. So, that it is important to have a parenting attitude that respects their children's emotion and expression.

• 대한가정학회지
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• 제32권5호
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• pp.109-124
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• 1994

The present study was conducted to elucidate the relationship between parent's verbal control modes and children's social competency. Two questionanires were developed by the authors for this study. The questionnaire for measuring parent's verbal control modes was composed of 84 and 87 items for mother and father, respectively, which assesses three types of verbal control modes; imperative control position-oriented control and person-oriented control. The questionnaire for measuring children's social competency perceived by mothers was composed of 27 items, which assesses four areas of social competency; initiative sociability responsibility and self-disclosure. the subjects of this study were 436 mothers and their children of fifth and sixth grade in elementary schools located in Seoul. The results of this study were as follows: 1) Parents control their children mostly by position-oriented mode and least by imperative mode. 2) There were significant correlations between father's verbal control mode and children's social competency. children's social competency was related positively to the person-oriented and position-oriented modes but negatively to the imperative mode. The best variables explaining boy's social competency were father's imperative and position-oriented modes whereas that for girl's was position oriented mode. 3) Mother's verbal control mode was not significant in explaining children's social competency. 4) The negative impact of father's imperative mode in combination with the mother's person-oriented mode on the children's social competency was greater than other combinations of father's and mother's verbal control modes.

• 대한인간공학회지
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• 제36권1호
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• pp.1-7
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• 2017

Objective: Two control rooms of a petroleum complex were ergonomically evaluated for this study using diverse drawings of the rooms. The objective of the study is to show the evaluation process and its results, assessment method and essential elements for drawing-based ergonomic evaluation. Background: Ergonomics can enhance the working environment and safety for a control room when implemented effectively. A control room design was examined by ergonomists based on ergonomic principles and well-practiced standards. This study was conducted because a construction consortium wanted to perform an ergonomic evaluation of the control rooms before the construction. Method: A simple evaluation process, composed with a pre-evaluation, an evaluation and a post-evaluation, was employed to carry out the study. ISO 11064, NUREG-0700, NUREG/CR-6150, and CRIOP were reviewed to evaluate the control rooms. The assessment ranges over the control room layout, workstations, display and control, environmental requirements and safety. Three ergonomists participated in the study and performed the evaluation for two months. Results: An experienced consortium of construction companies designed the petroleum complex and control rooms. No significant ergonomic design problems were detected. Quantitative recommendations were provided for the layout and workstation dimensions. Specific design directions were also proposed for environmental requirements and safety. Conclusion and Application: Design advice and minor potential problems were reported as results of the drawing-based ergonomic evaluation. More practical suggestions could be additionally provided if an on-site assessment was conducted. However, the ergonomic evaluation used in this study could be helpful and applied to designing and evaluating other various control rooms prior to their construction.

• 아동학회지
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• 제33권3호
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• pp.1-22
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• 2012

The purpose of this study was to examine the relationships between parents' control, affectionate parenting behavior, preschooler's effortful control, prosocial behavior, and cognitive problem-solving ability. The subjects for this study comprised 221 preschoolers (104 boys, 117 girls) and their parents. The major results of this study were as follows. First, parents' effortful control revealed direct effects upon preschooler's effortful control, and affectionate parenting behavior mediated the effects of parents' effortful control upon preschooler's effortful control. Second, preschooler's effortful control mediated the effects of affectionate parenting behavior upon preschooler's prosocial behavior. Third, preschooler's effortful control had direct effects upon prosocial behavior, and prosocial behavior mediated the effects of preschooler's effortful control upon cognitive problem-solving ability. In conclusion, parents' effortful control and affectionate parenting behavior impacted upon preschooler's effortful control. And preschooler's effortful control had an important role upon prosocial behavior and cognitive problem-solving ability.

• Journal of Advanced Marine Engineering and Technology
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• 제20권3호
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• pp.110-120
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• 1996

The purpose of this study is to build up the control scheme that promptly controls the pressure in a hydraulic cylinder having small control volume, using a PCV(proportional control valve) and a digital computer. Object pressure control system has the character to be unstable easily, because the displacement-flow gain of the PCV is so large considering comparatively small volume of the hydraulic cylinder and the time delay of response of PCV is long. Considering the above-mentioned characteristics of the object pressure control system, in this study, a control system is designed with two degree of freedom scheme that is composed by adding a feed-forward control path to I-PD control system, and the reference model is used to decide control parameters. And through some experiments on FF-I-PD, the validity of this control method is confirmed.

• Structural Engineering and Mechanics
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• 제38권2호
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• pp.141-156
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• 2011

A cable stayed bridge under construction has low structural damping and is not as stable as the completed bridge. Control countermeasures, such as the installation of energy dissipating devices, are thus required. In this study, the general procedure and key issues on adopting an active control device, the active mass damper (AMD), for vibration control of cable stayed bridges under construction were studied. Taking a typical cable stayed bridge as the prototype structure; a lab-scale test structure was designed and fabricated firstly. A baseline FEM model was then setup and updated according to the modal parameters measured from vibration test on the structure. A numerical study to simulate the bridge-AMD control system was conducted and an efficient LQG-based controller was designed. Based on that, an experimental implementation of AMD control of the transverse vibration of the bridge model was performed. The results from numerical simulation and experimental study verified that the AMD-based active control was feasible and efficient for reducing dynamic responses of a complex structural system. Moreover, the discussion made in this study clarified some critical problems which should be addressed for the practical implementation of AMD control on real cable-stayed bridges.