• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.1-6
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• 2013

A LEO satellite transmits recorded images to a ground station using an X-band antenna during contact. The X-band antenna points to the ground station according to a TPF (tracking parameter file) during communication time. A TPF generation software generates azimuth and elevation profile which make the antenna point to the ground station using satellite orbit and attitude information and mission information including recording and downlink operation. When the satellite passes above the ground station, azimuth velocity increases rapidly so that jitter may occur if the azimuth velocity is in specific range. In case of realtime mission in which the satellite perform recording and downlink simultaneously, azimuth velocity must be lower than specific value to prevent image blur due to jitter effect. The method to point one virtual ground station has limitation of azimuth velocity reduction. In this paper, we propose the azimuth fixing method to reduce azimuth velocity of X-band antenna. The experimental results show that azimuth velocity of the X-band antenna is remarkably reduced using proposed method.

• ETRI Journal
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• v.30 no.6
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• pp.774-782
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• 2008

An operational orbit determination (OD) and prediction system for the geostationary Communication, Ocean, and Meteorological Satellite (COMS) mission requires accurate satellite positioning knowledge to accomplish image navigation registration on the ground. Ranging and tracking data from a single ground station is used for COMS OD in normal operation. However, the orbital longitude of the COMS is so close to that of satellite tracking sites that geometric singularity affects observability. A method to solve the azimuth bias of a single station in singularity is to periodically apply an estimated azimuth bias using the ranging and tracking data of two stations. Velocity increments of a wheel off-loading maneuver which is performed twice a day are fixed by planned values without considering maneuver efficiency during OD. Using only single-station data with the correction of the azimuth bias, OD can achieve three-sigma position accuracy on the order of 1.5 km root-sum-square.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.7
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• pp.492-497
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• 2011

The objective of this research is to study the variation of optimum slope angles of collectors for seven regions in Korea, which are Seoul, Gangneung, Daejeon, Daegu, Gwangju, Busan and Jeju. The results for 2000~2007 are analyzed to sec if adjustment of slope angles is necessary each year to receive maximum solar radiation. For an azimuth fixed solar collector, solar radiation of yearly optimized slope angle during May~Sept.(summer), Nov.~Mar.(winter) and the whole year are greater than the fixed slope angle by 0.03%, 0.02%, and 0.04%, respectively. For an azimuth tracking solar collector, solar radiation of yearly optimized slope angle during May~Sept.(slimmer), Nov.-Mar.(winter) and the whole year are greater than the fixed slope angle by 0.03%, 0.07%, and 0.04% respectively. It is unnecessary to adjust slope angles each year for both azimuth fixed and tracking collectors, since the gains are insignificant. Solar radiation of the azimuth tracking solar collector during May~Sept., Nov.~Mar. and the whole year are greater by 14.7%, 16.0%, and 19.2% than the azimuth fixed solar collector.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.2
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• pp.191-196
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• 2014

The solar water heating system is one of the seven green campus items installed at the Gangneung campus of Gangneung-Wonju National University. The solar water heating system has two types of solar collectors, four storage tanks and monitoring equipment. Fixed and azimuth-tracking solar collectors were installed to collect heat from the sun. The amount of heat collected by the two different types of solar collectors was calculated from the temperature of the monitored storage tanks. Our results showed that the amount of solar heat collected by the azimuth-tracking solar collector was 19% greater on a sunny day and 23% greater on a rainy day than that collected by the fixed solar collector; therefore, the azimuth-tracking solar collectors are, on an average, 21% more efficient than the fixed solar collectors.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.132-138
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• 2009

In this paper, control of an omni-directional mobile robot is presented. Relying on encoder measurements to define the azimuth angle yields the dead-reckoned situation which the robot fails in localization. The azimuth angle error due to dead-reckoning is compensated and corrected by the magnetic compass sensor. Noise from the magnetic compass sensor has been filtered out. Kinematics and dynamics of the omni-directional mobile robot are derived based on the global coordinates and used for simulation studies. Experimental studies are also conducted to show the correction by the magnetic compass sensor.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2541-2546
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• 2013

In this paper, we proposed on the azimuth correction method for a line-of-sight data-link tracking antenna system. Tracking antenna system is essential to maintain line-of-sight between moving object and data-link equipment. In order to calculate the azimuth and elevation between the moving object and antenna system, we used GPS data. also to match the each coordinate systems, we used geomagnetic sensor or beacon. However, the geomagnetic disturbance-prone terrain in places difficult to correct calibration. The first step, finds the location of the strongest RF signal, we should remember the difference between the reference point and the detected position of the antenna. The second step, we could communicate each other. And the azimuth angle is calculated by GPS values. Despite the geomagnetic interference, we can correct the azimuth angle quickly and easily.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.165-165
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• 2000

The sunlight tracking and reflexing system can be divided into two parts. One is a sunlight tracking system and the other is a sunlight reflexing system. The sunlight tracking system detects an azimuth angie and an elevation angle of the sun using 2-axis sensor sun tracker. The sunlight reflexing system controls a reflection mirror to be reflected a sunlight at the target area after getting the azimuth angle and the elevation angle of the sun from the sunlight tracking system. We applied the fuzzy PID controller to control the reflexing mirror.

• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.129-137
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• 2012

This thesis introduced an azimuth tracking prismatic daylighting system. The system improved several issues of the previous passive prismatic daylighting system: low efficiency at sunrise and sunset, glare effect and polarized. The system was developed to track the movement of sun with azimuth tracking device, and it has its own power from the attached solar cells. We compared the with previous passive one in terms with system efficiency and daylighting factors(DF).

• KIEAE Journal
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• v.12 no.1
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• pp.113-118
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• 2012

The photovoltaic is one of the most important sustainable technologies appliable to architectures. The power performance mainly depends on the installation conditions of them. This study aims to evaluate the power performance of photovoltaic system by the installation conditions, the tracking methods and reflecting mirrors. For the study, the Solar Pro computer simulations have been conducted on installation angles, solar azimuth and solar altitude. Also, the field mock-up tests are performed to of its application to verify the simulation results. Both the results of the experiment and the simulation have proved that the efficiency of 90-degree fixed angle method was higher than that of 30-degree fixed angle, the efficiency of altitude tracking was better than that of azimuth tracking method, and changing both the altitude and the azimuth together is more efficient rather than the shortened tracing way. In addition, the light-concentrating method in which the incidence angle of the sun is controlled by an adhered reflector has been analyzed to have better efficiency than the general method of tracing according to the orbit of the sun. Therefore, this thesis is expected to offer the basic data to set a more effective tracing-type of photovoltaic power generation system in the future. For this, more researches are to be conducted hereafter on a high efficiency drive motor and the establishment of an economic system.

• Solar Energy
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• v.19 no.4
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• pp.81-91
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• 1999

The work presented here is a design and development of sun tracking system for the parabolic dish concentrator. Parabolic dish concentrator is mounted on azimuth and elevation tracking mechanism, and controlled to track the sun with computed and measured sun positions. Sun tracking mechanism is composed of 1/30000 speed reducer(3 stages) and 400W AC servomotor for each axis. The nominal tracking speed of each axis is ${\pm}0.6^{\circ}/sec$ and the system has a driving range of $340^{\circ}$ in azimuth and of $135^{\circ}$ in elevation. Sun tracking control system consists of sun sensor, wind speed and direction measurement system, AC servomotor position control system and personal computer as a master controller. Sun sensor detects the sun located within ${\pm}50^{\circ}$ measured from the sun sensor normal direction. Computer computes the sun position, sunrise and sunset times and controls the orientation of parabolic dish concentrator through the AC servomotor position control system. It also makes a decision of whether the system should follow the sun or not based on the information collected from sun sensor and wind speed and direction measurement system. The sun tracking system developed in this work is implemented for the experimental work and shows a good sun tracking performance.