• International Journal of Control, Automation, and Systems
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• v.6 no.2
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• pp.204-213
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• 2008

In this paper, we present the practical application of an Unscented Kalman Filter (UKF) for an Indoor Mobile Localization System using ultrasonic sensors. It is true that many kinds of localization techniques have been researched for several years in order to contribute to the realization of a ubiquitous system; particularly, such a ubiquitous system needs a high degree of accuracy to be practical and efficient. Unfortunately, a number of localization systems for indoor space do not have sufficient accuracy to establish any special task such as precise position control of a moving target even though they require comparatively high developmental cost. Therefore, we developed an Indoor Mobile Localization System having high localization performance; specifically, the Unscented Kalman Filter is applied for improving the localization accuracy. In addition, we also present the additive filter named 'Pre-filtering' to compensate the performance of the estimation algorithm. Pre-filtering has been developed to overcome negative effects from unexpected external noise so that localization through the Unscented Kalman Filter has come to be stable. Moreover, we tried to demonstrate the performance comparison of the Unscented Kalman Filter and another estimation algorithm, such as the Unscented Particle Filter (UPF), through simulation for our system.

• Physical Therapy Korea
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• v.28 no.1
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• pp.36-46
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• 2021

Background: It is reported that the proprioceptive sensation of patients with neck pain is reduced, and neck sensory-motor control training using visual feedback is reported to be effective. Objects: The purpose of this study is to investigate how sensorimotor control training for the cervical spine affects pain, function, and psychosocial status in patients with chronic cervical pain. Methods: The subjects consisted of 36 adults (male: 15, female: 21) who had experienced cervical spine pain for more than 6 weeks. An exercise program composed of cervical stabilization exercise (10 minutes), electrotherapy (10 minutes), manual therapy (10 minutes), and cervical sensorimotor control training (10 minutes) was implemented for both the experimental and the control groups. The cervical range of motion (CROM) and head repositioning accuracy were assessed using a CROM device. In the experimental group, the subjects wore a laser device on the head to provide visual feedback while following pictures in front of their eyes; whereas, in the control group, the subjects had the same training of following pictures without the laser device. Results: There were no statistically significant differences between the two groups in pain, dysfunction, range of motion, or psychosocial status; however, post-test results showed significant decreases after 2 weeks and 4 weeks compared to baseline (p < 0.01), and after 4 weeks compared to after 2 weeks (p < 0.01). The cervical joint position sense differed significantly between the two groups (p < 0.05). Conclusion: In this study, visual feedback enhanced proprioception in the cervical spine, resulting in improved cervical joint position sense. On the other hand, there were no significant effects on pain, dysfunction, range of motion, or psychosocial status.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.229-231
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• 1994

In recent years, as the industry has been highly developed and precised, its driving and control system have been changed, what is more, revolutionized. The requirements of these change are more accuracy, more high efficiency, more miniaturized size and more servo functions. Step motor has been adopted for driving servo systems, because of easier controllability, open-loop control, high position accuracy at low speed. In this paper, we deal with developing step motor system, and describe the procedure that contains design, analysis. testing characteristics.

• ETRI Journal
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• v.26 no.3
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• pp.218-228
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• 2004

Using stereo images with ephemeris data from the Korea Multi-Purpose Satellite-1 electro-optical camera (KOMPSAT-1 EOC), we performed geometric modeling for three-dimensional (3-D) positioning and evaluated its accuracy. In the geometric modeling procedures, we used ephemeris data included in the image header file to calculate the orbital parameters, sensor attitudes, and satellite position. An inconsistency between the time information of the ephemeris data and that of the center of the image frame was found, which caused a significant offset in satellite position. This time inconsistency was successfully adjusted. We modeled the actual satellite positions of the left and right images using only two ground control points and then achieved 3-D positioning using the KOMPSAT-1 EOC stereo images. The results show that the positioning accuracy was about 12-17 m root mean square error (RMSE) when 6.6 m resolution EOC stereo images were used along with the ephemeris data and only two ground control points (GCPs). If more accurate ephemeris data are provided in the near future, then a more accurate 3-D positioning will also be realized using only the EOC stereo images with ephemeris data and without the need for any GCPs.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.615-621
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• 2013

The robot calibration has greatly improved the absolute accuracy of the industrial robot. However, the accuracy of the relative positions of robotic tool-tip at work-points on a work-piece is only slightly corrected by the robot calibration since there has been no practical method to eliminate the elements of the setup position errors at a robotic workplace. A robotic workplace calibration is demonstrated in this paper to minimize the relative position errors between a robot tool-tip and the work-point on a work-piece. The existing teaching and playback method has been developed for the robotic workplace calibration. This paper uses the work-piece fixed in a robotic work-place as measurement equipment instead of a special robot measurement equipment for the robotic workplace calibration. The positive effect of the robotic workplace calibration is supported by the results of computer simulation on an ideal robotic workplace model and an experiment at the actual robotic workplace.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.22-28
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• 2003

In the conventional weapon system, such as gun and small arms, it Is a general trend that for maximization of its performance and enhancement of its effectiveness, the firing control system(FCS) is developed and applied with the guns and small arms in the world. The FCS of the small arms for infantry man is composed of a few of sensors for acquisition of input data of FCS, such as range measurement, position sensing of weapon, temperature, etc., computer, displayer and power pack, and also the air burst munition is developed in parallel for the maximization of FCS's effectiveness. Since the flight time setting fuze for the air burst munition is adapted for next me, the measuring device of the muzzle velocity is needed to overcome the variation of muzzle velocity due to producing procedures and the differences of the using temperatures and so maintain the burst position accuracy This paper contained the technical information on the development of the measuring device of muzzle velocity, which designed in compact & light weight configuration with reliability and accuracy.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.2
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• pp.104-110
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• 1984

An electro-hydraulic copying system is developed and its performance is experimentally investigated. As compared with a mechanical hydraulic coping system, this system has a basic difference in that; (1) the stylus movement is converted into an electrical signal via a position transducer. (2)the actuator displacement is also measured by a position sensing element, which serves as a feedback signal. Since the system parameters affect the control performance, the response characteristics such as percentage overshoot, rise time, settling time and steady state error are experimentally obtained under variation of these variables. The system parameter include supply pressure, servo amplifier gain and feedback gain. The experimental result shows that the cutting tool follows a stylus input motion to a desirable accuracy. The implication of this result indicates that the developed system can enhance the copying accuracy of the conventionally used mechanical type of hydraulic copying system.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.1
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• pp.72-78
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• 2007

Determination of the local vertical is not trivial for a moving vehicle and in general will require corrections for the Earth geophysical deflection. The vehicle's local vertical can be estimated by INS integration with initial alignment in SDINS(Strap Down INS) system. In general, the INS has drift error and it cause the performance degradation. In order to compensate the drift error, GPS/INS augmented system is widely used. And in the event that GPS is denied or unavailable, celestial navigation using star tracker can be a backup navigation system especially for the military purpose. In this celestial navigation system, the vehicle's position determination can be achieved using more than two star trackers, and the accuracy of position highly depends on accuracy of local vertical direction. Modern tilt sensors or accelerometers are sensitive to the direction of gravity to arc second(or better) precision. The local gravity provides the direction orthogonal to the geoid and, appropriately corrected, toward the center of the Earth. In this paper the relationship between direction of center of the Earth and actual gravity direction caused by geophysical deflection was analyzed by using precision orbit simulation program embedded the JGM-3 geoid model. And the result was verified and evaluated with mathematical gravity vector model derived from gravitational potential of the Earth. And also for application purpose, the performance variation of pure INS navigation system was analyzed by applying precise gravity model.

• Journal of Power System Engineering
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• v.17 no.5
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• pp.100-111
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• 2013

Indoor real-time positioning for multiple targets is required to realize human-robot symbiosis. This study firstly presents positioning accuracy on an autonomous mobile robot controlled by 3-D coordinates that is obtained by a real-time indoor positioning system with spread spectrum (SS) ultrasonic signals communicated by code-division multiple access. Although many positioning systems have been investigated, the positioning system with the SS ultrasonic signals can measure identified multiple 3-D positions in every 70 ms with noise tolerance and error within 100 mm. This system is also robust to occlusion and environmental changes. However, thus far, the positioning errors in an autonomous mobile robot, controlled by these systems using the SS ultrasonic signals, have not been evaluated as an experimental study. Therefore, a positioning experiment for trajectory control is conducted using an autonomous mobile robot and our positioning system. The effectiveness of this positioning method for robot self-localization is shown, from this experiment, because the average control error between the target position and the robot's position at 29 mm is obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.628-633
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• 2018

The accuracy of GNSS depends on several factors from the equipment used in data processing because GNSS positioning can be used differently depending on the accuracy required. In the case of the control point surveying requiring high accuracy, GNSS surveying is performed using the relative positioning method, and the observation time and data processing s/w are used differently depending on the class of the control points. On the other hand, the accuracy of academic software depends on the skill of the user, so it may be better to use commercial software in the case of a short baseline. In this study, the results of GNSS survey data were compared using scientific software and commercial software. The results showed that the horizontal position showed a difference of less than 2 cm and the height showed a difference of less than 5 cm. These differences were found to be in the error ranges specified in the unified control point survey regulations. Based on the above results, the commercial s/w can be used for GNSS data processing at the midterm baseline rather than the long baseline.