• International Journal of Aeronautical and Space Sciences
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• v.15 no.2
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• pp.190-198
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• 2014

The pyramidal reaction wheel arrangement is one of the configurations that can be used in attitude control simulators for evaluation of attitude control performance in satellites. In this arrangement, the wheels are oriented in a pyramidal configuration with a tilt angle. In this paper, a study of pyramidal reaction wheel arrangement is carried out in order to find the optimum tilt angle that minimizes total power consumption of the system. The attitude control system is analyzed and the pyramidal configuration is implemented in numerical simulation. Optimization is carried out by using an iterative process and the optimum tilt angle that provides minimum system power consumption is obtained. Simulation results show that the system requires the least power by using optimum tilt angle in reaction wheels arrangement.

• International Journal of Control, Automation, and Systems
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• v.4 no.4
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• pp.480-485
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• 2006

In this paper, the error investigation of a 3-dimensional GPS attitude determination system using the error covariance analysis is given. New efficient formulas for computing the Euler Angle Dilution of Precision (EADOP) are also derived. The formulas are easy to compute and represent the attitude error as a function of the nominal attitude of a vehicle, the baseline configuration and the receiver noise. Using the formula, the accuracy of the Euler angle can be analytically predicted without the use of computer simulations. Applications to some configurations reveal the effectiveness of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.6
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• pp.608-611
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• 2012

This paper focuses on attitude stabilization performance improvement of the quadrotor flying robot. First, the dynamic model of quadrotor flying robot was estimated through PEM (Prediction Error Method) using experimental input/output data. And attitude stabilization performance was improved by increasing the generation frequency of PWM signal from 50 Hz to 500 Hz. Also, the controller is implemented using a standard PID (Proportional-Integral-Derivative) controller augmented with feedback on angular acceleration, allowed the gains to be significantly increased, yielding higher bandwidth. Improved attitude stabilization performance is verified by experiment.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.129-139
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• 2007

In this paper, attitude control laws for simultaneous pointing of multiple spacecrafts are considered under a formation flying scenario. The basic approach lies in adaptive feedback gains using relative attitude information or maneuver time approximation for coordinated attitude control. Each control law is targeted to balancing mean motion or to correcting system response to the slowest satellite. The control gain adaptation is constructed by two approaches. The first one is using variable damping gain to manipulate speed of a fast system response, and the second one uses alternate natural frequency of the system under control. The validity and stability of the proposed approaches are examined analytically and tested through numerical simulations.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.703-710
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• 2007

This paper presents an attitude determination scheme for the Science and Technology Satellite-2(STSAT-2) using Fine Digital Sun Sensor(FDSS). The FDSS has been developed for STSAT-2, and exhibits the accuracy of 0.032degree in $1{\sigma}$. To be specific, the attitude information from the sensor is exploited to compensate for Fiber Optic Gyro(FOG) mounted on STSAT-2, and Kalman filter model is derived and implemented. To show the effectiveness of the present compensation scheme, computer simulations have been carried out resulting in the attitude errors within a bound.

• Child Health Nursing Research
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• v.16 no.3
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• pp.195-202
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• 2010

Purpose: The purpose of this study was to examine the influence of parents rearing attitude on family cohesion and adolescents' self-esteem. Methods: The participants were 1,299 high school students from Seoul city and Kyunggi Province in Korea. Data were collected using self-report questionnaire and analyzed using descriptive statistics, Pearson correlation coefficients, stepwise regression with SPSS 14.0 win program. Results: The major results are as follows. First, parents rearing attitude was significantly influence to the family cohesion. Second, parents rearing attitude and family cohesion were significantly affect to the adolescent self- esteem. Third, compare the influence size between the parents rearing attitude and family cohesion to the adolescent self- esteem, the family cohesion was higher than the parents rearing attitude. Conclusion: The finding may provide useful insight to researchers who want to develop social support program for adolescents.

• Korean Journal of Child Studies
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• v.25 no.6
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• pp.35-52
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• 2004

The purpose of this study is to explore the relation among mother's rearing attitude in infancy, children's self-concept and the relationship with friends in childhood by using the longitudinal data originated by the Korean Institute for Research in the Behavioral Sciences(KIRBS). Specifically, using Structural Equation Modeling(SEM), the causal relation among the mother's rearing attitude in infancy, children's self-concept and the relationship with friends in childhood were examined across a 8-year-period. The subjects were 68 children(38 boys and 30 girls) from the KIRBS longitudinal data. The results showed that mother's rearing attitude in infancy can be consequential environmental variable factor, and children's self-concept do not play an essential intermediate role between mother's rearing attitude in infancy and the relationship with friends in childhood. This study used a newly attempted method in the field of Human Development.

• Korean Journal of Remote Sensing
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• v.22 no.1
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• pp.63-73
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• 2006

Currently, in order to achieve accurate geolocation of satellite images we need to generate control points from individual scenes. This requirement increases the cost and processing time of satellite mapping greatly. In this paper we investigate the feasibility of modeling entire image strips that has been acquired from the same orbital segments. We tested sensor models based on satellite orbit and attitude with different sets of unknowns. We checked the accuracy of orbit modeling by establishing sensor models of one scene using control points extracted from the scene and by applying the models to adjacent scenes within the same orbital segments. Results indicated that modeling of individual scenes with $2^{nd}$ order unknowns was recommended. In this case, unknown parameters were position biases, drifts, accelerations and attitude biases. Results also indicated that modeling of orbital segments with zero-degree unknowns was recommended. In this case, unknown parameters were attitude biases.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.553-558
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• 2002

Physical sensor model in pushbroom satellite images can be made from sensor modeling by rotation parameters and attitude parameters on the satellite track. These parameters are determined by the information obtained from GPS, INS, or star tracker. Provided from satellite image, an auxiliary data error is connected directly with an error of rotation parameters and attitude parameters. This paper analyzed how obtaining satellite images influenced errors of rotation parameters and attitude parameters. furthermore, for detailed analysis, this paper generated simulated satellite image, which was changed variously by rotation parameters and attitude parameters of satellite sensor model. Simulated satellite image is generated by using high-resolution digital aerial image and DEM (Digital Elevation Model) data. Moreover, this paper determined correlation of rotation parameter and attitude parameters through error analysis of simulated satellite image that was generated by various rotation parameters and attitude parameters.

• The Research Journal of the Costume Culture
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• v.16 no.6
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• pp.1126-1141
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• 2008

The purposes of this study identify how attributes of the website impact on consumer attitude toward the website. For this purpose, the study tested covariance structural model which set relationships among independent variables (interactivity and shopping value), meditated variables(relationship commitment), and dependent variables(attitude toward website). The data were collected from a sample of 239 internet shopper of college female students. The covariance structural model and research hypothesis analyzed by using SPSS 16.0 and AMOS 5.0 program. The results are as follows: First, the structural model is accepted significantly. Second, interactivity and shopping value of website have a positive influence on relationship commitment. Third, interactivity, shopping value of website, and relationship commitment have a positive impact on attitude toward the website. Forth, even if shopping value has not a positive influence on attitude toward the website, it was found to have a significant effect on attitude toward the website through the relationship commitment.