• Journal of Astronomy and Space Sciences
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• v.23 no.4
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• pp.385-396
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• 2006

The International GNSS Service (IGS) has prepared for a transition from the relative phase conte. variation (PCV) to the absolute PCV, because the terrestrial scale problem of the absolute PCV was resolved by estimating the PCV of the GPS satellites. Thus, the GPS data will be processed by using the absolute PCV which will be an IGS standard model in the near future. It is necessary to compare and analyze the results between the relative PCV and the absolute PCV for the establishment of the reliable processing strategy. This research analyzes the effect caused by the absolute PCV via the GPS network data processing. First, the four IGS stations, Daejeon, Suwon, Beijing and Wuhan, are selected to make longer baselines than 1000km, and processed by using the relative PCV and the absolute PCV to examine the effect of the antenna raydome. Beijing and Wuhan stations of which the length of baselines are longer than 1000km show the average difference of 1.33cm in the vertical component, and 2.97cm when the antenna raydomes are considered. Second, the 7 permanent GPS stations among the total 9 stations, operated by Korea Astronomy and Space Science Institute, are processed by applying the relative PCV and the absolute PCV, and their results are compared and analyzed. An insignificant effect of the absolute PCV is shown in Korea regional network with the average difference of 0.12cm in the vertical component.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.9-14
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• 2006

A determinated position with GPS (Global Positioning System) data processing is the position of the phase center of a GPS antenna. The phase center of a GPS antenna is. not a stable point and depends on the azimuth and elevation angles of GPS satellites. It is known that the phase center variations (PCV) of a GPS antenna are greater in the vertical than the horizontal directions. The PCV calibration models for a GPS. antenna has two approaches: relative and absolute. In this study. we compared the two calibration models using the six operational permanent GPS stations in South Korea and analysed the PCV of each station. In addition, we. tested two different kinds of GPS antennas and compared the results. The accuracy and precision of the relative calibration was worse than the absolute calibration.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.41-45
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• 2006

To get accurate positions of GPS antennas, one should apply phase center variations (PCV) corrections in the data processing. Until recently, relative calibrations, originally proposed by National Geodetic Survey of United States, were the international standard. However, in late 2006, International GNSS Service will switch to absolute calibration methods. In this study, we compared the position differences caused by different PCV models, and their effects on the calculations of Precipitable Water Vapor (PWV) in the atmosphere. Data from ${\sim}40$ permanent GPS stations in Korea were processed and we found that the vertical position differences reach up to 5 cm, depending on the model selected. Also the PWV values varied quite significantly: the maximum bias in the computed PWV values was ${\sim}4$ mm.

• Journal of Veterinary Clinics
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• v.28 no.4
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• pp.357-364
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• 2011

To evaluate hepatoprotective effect of Epimedium Koreanum nakai (EKN) on liver-damaged animal model, rats were intoxicated with carbon tetrachloride (1 ml/kg) for 9 weeks orally. Liver-damaged rats were divided into 2 groups: liver-damaged control (LDC) group and EKN group were administered vehicle (saline), EKN extract per os for 4 weeks respectively. Normal control (NC) group was administered saline as the same process of LDC group. The weights of prostate (absolute), testis (relative), epididymis (relative) and packed cell volume (PCV), mean corpuscular volume (MCV) of EKN group significantly (P < 0.05) increased compared with LDC group. But Mean corpuscular hemoglobin (MCH), mean corpusulcar hemoglobin concentration (MCHC) and aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) were significantly (P < 0.01, P < 0.05) decreased. Fibrotic regions in hepatic parenchyma of EKN group significantly (P < 0.01) decreased compared with LDC group and mean diameters of hepatic lobules significantly (P < 0.01) increased. Percentages of degenerative kidney regions and number of degenerative kidney tubules, number of vasodilated atrophic glomerulus of EKN group was significantly (P < 0.01, P < 0.05) decreased compared with LDC group. Number of atrophic seminiferous tubules and epididymal tubules showing oligospermatozoa of EKN group were significantly (P < 0.01) decreased compared with LDC group. In conclusion, EKN extract has a favorable effect on the $CCl_4$-induced liver damage.