• Journal of Korea Multimedia Society
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• v.12 no.2
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• pp.300-312
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• 2009

An indoor location-based service cannot be realized unless the indoor positioning problem is solved. However, the cost-effective indoor positioning systems are suffering from their inaccurateness. This paper proposes a map information-based correction method for the indoor positioning systems. Using our Kalman filter with map information-based appropriate parameter values, our method estimates the track of the moving object, then it performs the Frechet Distance-based map matching on the obtained track. After that it applies our real time correction method. In order to verify efficiency of our method, we also provide our test results.

• Korean Journal of Remote Sensing
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• v.10 no.2
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• pp.133-160
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• 1994

In this paper, we propose a comprehensive geometric correction algorithm of Along Track Scanning Radiometer(ATSR) images. The procedure consists of two cascaded modules; precorrection and fine co-location. The pre-correction algorithm is based on the navigation model which was derived in mathematical forms. This model was applied for correction raw(un-geolocated) ATSR images. The non-systematic geometric errors are also introduced as the limitation of the geometric correction by this analytical method. A fast and automatic algorithm is also presented in the paper for co-locating nadir and forward views of the ATSR images by using a binary cross-correlation matching technique. It removes small non-systematic errors which cannot be corrected by the analytic method. The proposed algorithm does not require any auxiliary informations, or a priori processing and avoiding the imperfect co-registratio problem observed with multiple channels. Coastlines in images are detected by a ragion segmentation and an automatic thresholding technique. The matching procedure is carried out with binaty coastline images (nadir and forward), and it gives comparable accuracy and faster processing than a patch based matching technique. This technique automatically reduces non-systematic errors between two views to .$\pm$ 1 pixel.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.18-21
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• 2021

This paper analyzes the distortion correction of the in the micro DMD(digital micro mirror device) projector system using 0.25 or less optical throwing distance ratio. The distortion of projected image occurs depending on the performance of the optical lens, the installation location of the projection system, and the tilt of the screen. This study analyzed the physical tilt values influencing of the distortion of projected image, removed the tilt distortion of throwing distance ratio optical lens, and adjusted the distortion image by the simulation of calibration displacements. The results of this study demonstrated within 5% TV distortion reference. Moreover, the correction method reduced the pin-distortion correction of projection system.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.2
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• pp.141-148
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• 2023

In this paper, impacts of tropospheric delay gradient correction on PPP positioning performance were analyzed. A correction for tropospheric delay error due to the gradient was created and applied using external data, and reference station data were collected on a sunny day and a rainy day to analyze the GPS only dual-frequency PPP positioning results. As a result, on the sunny day, the convergence time was about 35 minutes and the final 3D position error was 10 cm, regardless of whether the correction for the tropospheric delay error by the gradient was applied. On the other hand, on the rainy day, the 3D position error converges only when the correction was applied, and the convergence time was about 34 minutes. Furthermore, the final 3D position error was improved from 30 cm to 10 cm. In addition, the analysis of the PPP by reference station location on the rainy day showed that the PPP positioning performance was improved when the correction was applied to a user located in an area where the weather changes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.119-126
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• 2011

In this paper, we expect that the IEEE 802.15.4a, which is based on CSS, will be used a lot without getting help from other systems or sensors and will make it possible to measure the distance between radio chips in sensor network field, where the location information of the standard have to be based upon. But, the error rate will be high, so we will correct the location of the tag, which will be received by anchor. The technology of location correction we offer is reducing the error rate through calculating the distance from Compensation Tag, and after that, unite the Toa method with the Fingerprint method and adapt them to location correction technology, calculate the location's estimate, and finally abstract the best suited location estimate for Compensation Tag. At last, we offer developing systems as indoor systems of CSS, which pursue the location between nodes, and a thesis about indoor systems and making their accuracy higher.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.3
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• pp.448-458
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• 2020

Indoor positioning based on trilateration using common chord estimates location of a mobile subject by using intersection points between each circles which the radius is same as distance between the mobile subject and each radio-frequency transmitter. However, if the intersection points are not found due to error of the distance measurement, it causes failure of estimating the mobile subject's location. To prevent this case, numbers which is proportionate to radius of each circles, are temporarily added to each distances in order to lengthen radius of the circles. Although the estimated location includes error due to the radius extension, it is corrected again by the added value and distance from reference point. With introduction of the advanced correction algorithm, potential issues of existing trilateration such as failure of estimating location and distance measurement error will be minimized.

• KIISE Transactions on Computing Practices
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• v.21 no.12
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• pp.798-803
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• 2015

DGPS is a technology that can improve the positioning precision of the existing GPS based on the correction information regarding reference station. Although the country is currently building infrastructure for DGPS correction information to be transmitted, it is being used only in limited areas for which DGPS expensive equipment is required. By enabling the development of the DGPS device using the smart phone, this limitation can be overcome, DGPS can be applied for various location-based services, and the implementation of the new model of location-based services may be enabled. In this paper, we introduce the development of a DGPS device for which high-precision positioning is possible using DGPS correction information received via the DMB network or mobile network in the smart phone environment.

• Journal of Digital Contents Society
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• v.16 no.2
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• pp.179-187
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• 2015

Spread of smartphone creates various contents. Among many contents, AR application using Location Based Service(LBS) is needed widely. In this paper, we propose error correction algorithm for location-based Augmented Reality(AR) system using computer vision technology in android environment. This method that detects the early features with SURF(Speeded Up Robust Features) algorithm to minimize the mismatch and to reduce the operations, and tracks the detected, and applies it in mobile environment. We use the GPS data to retrieve the location information, and use the gyro sensor and G-sensor to get the pose estimation and direction information. However, the cumulative errors of location information cause the mismatch that and an object is not fixed, and we can not accept it the complete AR technology. Because AR needs many operations, implementation in mobile environment has many difficulties. The proposed approach minimizes the performance degradation in mobile environments, and are relatively simple to implement, and a variety of existing systems can be useful in a mobile environment.

• Journal of Korea Multimedia Society
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• v.19 no.10
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• pp.1767-1774
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• 2016

In this paper, we propose the adaptation filtering for correcting the movement path of the recognized object by the depth information. When we recognize the object by the depth information, the path error should be occurred because of the noises in the depth information. The path error is corrected by appling the lowpass filtering, but the lowpass filtering is not efficient when the changes of the object's movement are rapid. In this paper, we apply the adaptation filtering that it gives weights adaptively as the difference between the predicted location and the measured location. To apply the adaptation filtering, we can see that the proposed method can correct accurately the path error of the radical change from simulation results.

• International conference on construction engineering and project management
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• 2017.10a
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• pp.210-213
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• 2017

The construction industry has witnessed an exponential growth of drones used in the field over the past few years. Likewise, the field of maintenance has paid increasing attention to using drones with a view to improving the efficiency of condition checks in high-rise buildings and major space. Although operators manipulate drones to inspect buildings at present, drones are expected to autonomously move around without operators in a few years. Also, for indoor maintenance, it is important for drones to find accurate locations, which is implemented by real-time locating systems(RTLS). Yet, the accuracy of RTLS varies across the types of systems and indoor settings, which warrants a locating system suitable for indoor space and a location correction system designed to improve the accuracy. Hence, the current study investigated the accuracy of real-time locating systems(RTLS) for the maintenance of indoor space of buildings with drones and delved into the methods of correcting the location information to improve the accuracy of RTLS.