• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.386-389
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• 2007

Currently, fast and accurate long baseline positioning in kinematic mode is a challenging topic, but positional accuracy can be improved with the help of the network-derived external ionospheric corrections. To provide not only ionospheric corrections, but also their variances, satellite-by-satellite interpolation for the ionospheric delays is performed using the least-squares collocation (LSC) method. Satellite-by-satellite interpolation has the advantage in that the vertical projection used in single-layer ionospheric model is not required. Also, more reliable user positioning and the corresponding accuracy assessment can be obtained by providing not only external ionospheric corrections but also their variances. The rover positioning with and without the external ionospheric delays in both rapid-static and kinematic mode was performed and analyzed. The numerical results indicate that the improvement in the positioning quality is achieved using the proposed method. With the TAMDEF network in Antarctica, 18 % improvement in mean time-to-fix in kinematic mode was achieved.

• Asia Pacific Journal of Corpus Research
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• v.1 no.1
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• pp.1-30
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• 2020

The present study examines language used to talk about the global coronavirus pandemic during a three-month period of movement control order in Malaysia. More specifically, a corpus of online letters to the editor of a local popular national newspaper was collected during the time in which the official quarantine instruction was initiated, resulting in a total of 303 online letters written by Malaysians that were analyzed through use of corpus linguistics techniques. For this purpose, the latest version of #LancsBox 5.0 (Brezina et al., 2020) is used to analyze patterns of language surrounding the portrayal of Covid-19 and further visualizing them by use of collocation networks. Findings present 25 statistically significant collocates that share an interesting relationship in revealing what the letters are about and thus, reflecting how Malaysians perceive and receive news about the pandemic during this time. Recurring topics and expressions include describing the virus in terms of metaphorical use of language (Covid-19 does not discriminate), preparing for an economic fallout (Prihatin Economic Stimulus Package), and preference to associate Covid-19 as a pandemic (impacts of the Covid19 pandemic) rather than an outbreak (first/second/third wave of the outbreak). Implications of the study resonates with findings from Azizan et al. (2020) where constructions of positive discourse among Malaysian writers may reflect the culture and society that make up the nation.

• Korean Journal of Geomatics
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• v.5 no.1
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• pp.21-26
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• 2005

According to revisions of survey law taking effect on January 1, 2003, the Korean geodetic datum has been changed from a local geodetic to a world geodetic system. In this study, the datum transformation parameters especially for the maritime geographical data are determined. From database constructed through MGIS, a total of 492 coordinate pairs were selected and used in the parameter determination after outlier testing. Based on the parameter estimation, the Molodensky model is selected for datum transformation. For higher accuracy, Application of network optimization and a least squares collocation with Gaussian model has resulted in the accuracy better than 15 cm in coordinate transformation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.6
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• pp.699-710
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• 2009

If a country has her geoid model, it could be determine accurate orthometric height because the geoid model could provide continuous equi-gravity potential surface. And it is possible to improve the coordinates accuracy of national control points through geodetic network adjustment considering geoidal heights. This study aims to find the best way to develop geoid model in Philippines which have similar topographic conditions as like Malaysia and Indonesia in Eastsouth asia. So, in this study, it is surveyed the general theories of geoid determination and development cases of geoid model in Asia and it is computed that the geoidal heights and gravity anomalies by spherical harmonic analysis using EGM2008, the latest earth geopotential model. The results show that first, the development of gravimetric geoid model based on airborne gravimetry is needed and second, about 200 GPS surveying data at national benchmark is needed. It is concluded that it is the most reasonable way to develop the hybrid geoid model through fitting geometric geoid by GPS/leveling data to gravimetric geoid. Also, it is proposed that four band spherical Fast fourier transformation(FFT) method for evaluation of Stokes integration and remove and restore technique using EGM2008 and SRTM for calculation of gravimetric geoid model and least square collocation algorithm for calculation of hybrid geoid model.