• Journal of Korean Society for Geospatial Information Science
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• v.23 no.4
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• pp.43-48
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• 2015

We studied on pseudo-range correction(PRC) modeling in order to improve differential GNSS(DGNSS) accuracy. The PRC is the range correction information that provides improved location accuracy using DGNSS technique. The digital correction signal is typically broadcast over ground-based transmitters. Sometimes the degradation of the positioning accuracy caused by the loss of PRC signals, radio interference, etc. To prevent the degradation, in this paper, we have designed a PRC model through polynomial curve fitting and evaluated this model. We compared two quantities, estimations of PRC using model parameters and observations from the reference station. In the case of GPS, the average is 0.1m and RMSE is 1.3m. Most of GPS satellites have a bias error of less than ${\pm}1.0m$ and a RMSE within 3.0m. In the case of GLONASS, the average and the RMSE are 0.2m and 2.6m, respectively. Most of satellites have less than ${\pm}2.0m$ for a bias error and less than 3.0m for RMSE. These results show that the estimated value calculated by the model can be used effectively to maintain the accuracy of the user's location. However;it is needed for further work relating to the big difference between the two values at low elevation.

• Archives of Craniofacial Surgery
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• v.9 no.2
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• pp.85-89
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• 2008

Purpose: Unicoronal synostosis is the craniofacial anomaly caused by premature fusion of unilateral coronal suture. Ipsilateral flattening of the frontal and parietal bones, temporal retrusion with elevation and recession of the supraorbital rim are main clinical features. Compensatory contralateral frontal bossing and deviation of the nasal root and/or chin can also occur. There is a controversy about techniques for surgical correction, however, bilateral approach technique is more effective for correction of deformity. Methods: A 4-year-old patient with unicoronal synostosis had undergone unilateral suturectomy at 28-month-old but fronto-facial deformity had remained and aggravated as she grew older. She had both fronto-facial and endocranial asymmetry. We performed coronal cranial approach and fully exposed affected cranium including supraorbital rim. Anterior 2/3 calvarial reconstruction with bilateral frontal bone osteotomy and fronto-orbital bandeau advancement was performed. Results: Fronto-facial symmetry including fronto-orbital contour, nasal devation was improved. Endocranial twisting was also improved from $158^{\circ}$ to $162^{\circ}$ in CSO(crista gallisella turcica-opisthion) degree. There was no postoperative complications and no need for revision, and facial asymmetry improved at the period of 2 years of follow-up. Conclusion: Bilateral approach with fronto-orbital bandeau remodeling in surgery of unicoronal synostosis looked superior to unilateral approach in achieving better symmetry and preventing recurrence of asymmetry. Remodeling surgery should be tried in patients even at an older age to correct fronto-facial asymmetry.

• Journal of Navigation and Port Research
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• v.38 no.2
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• pp.121-126
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• 2014

This paper suggests a new algorithm to provide low-cost GPS modules with DGPS service, which corrects the error vector in the already-calculated position by projecting range corrections to position domain using the observation matrix calculated from the satellite elevation and azimuth angle in the NMEA GPGSV data. The algorithm reduced the horizontal and vertical RMS error of U-blox LEA-5H module from 1.8m/5.8m to 1.0m/1.4m during the daytime. The algorithm has advantage in improving the performance of low-cost module to that of DGPS receiver by a software update without any correction in hardware, therefore it is expected to contribute to the vitalization of the future high-precision position service infrastructure by reducing the costumer cost and vender risk.

• Archives of Craniofacial Surgery
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• v.20 no.3
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• pp.170-175
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• 2019

Background: Cryptotia is a congenital anomaly in which the upper part of the retroauricular sulcus is absent and buried underneath the temporal skin. Various surgical techniques have been reported for the correction of cryptotia following Kubo's V-Y plasty in 1933. Conventional methods using a local skin flap, skin grafting, tissue expansion, Z-plasty, and any of these combined approaches can result in skin deficiency of the upper auricle. The aim of this study was to develop a new method that improves cosmetic results and has fewer complications. Methods: This study involved four patients in whom five cryptotia deformities were corrected using V-Y plasty and Z-plasty. After elevation of the flap, acellular dermal matrix (ADM; MegaDerm) that was over 5 mm in thickness was applied to the cephalo-auricular angle and positioned to enhance the projection of the ear. Lastly, the flap was transposed to complete the repair. Results: Between January 2014 and February 2018, cryptotia correction with ADM graft was performed in four patients. None of the patients developed a recurrence of cryptotia, and there were no postoperative complications such as wound infection, seroma formation, and dehiscence. In addition, the procedures resulted in a favorable cosmetic appearance. Conclusion: Based on these findings, i.e., no recurrence and a favorable cosmetic result, when using an ADM graft, it is suggested that this technique could be an alternative method of cryptotia correction. It could also lessen donor-site morbidity when compared to autologous cartilage grafting and be more cost-effective than using cartilage from a cadaver.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.3
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• pp.317-328
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• 2010

This paper describes the results of complete Bouguer anomalies computed from the Free-air anomalies that derived from Sandwell and DNSC08 marine gravity models. Complete bouguer corrections consist of three parts: the bouguer correction (Bullard A), the curvature correction (Bullard B) and the terrain correction (Bullard C). These all corrections have been computed over the East Sea on a $1'{\times}1'$elevation data (topography and bathymetry) derived from ETOPO1 global relief model. In addition, a constant topographic (sea-water) density of $2,670kg/m^3$($1,030kg/m^3$) has been used for all correction terms. The distribution of complete bouguer anomalies computed from DNSC08 are -34.390 ~ 267.925 mGal, and those from Sandwell are -32.446 ~ 266.967 mGal in East Sea. The mean and RMSE value of the difference between DNSC08 and Sandwell is $0.036{\pm}2.373\;mGal$. The highest value of complete bouguer anomaly are found around the region of $42{\sim}43^{\circ}N$ and $137{\sim}139^{\circ}E$ (has the lowest bathymetry) in both models. These values show that the gravity distribution of both models, DNSC08 and Sandwell, are very similar. They indicate that satellite-based marine gravity model can be effectively used to analyze the geophysical, geological and geodetic characteristics in East Sea.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.5 no.1
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• pp.1-12
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• 1987

Using double-measurmented gravity values which observed by Lacoste instrument, drifts and MSE are analized after TIDE correction and Bouguer reduction is investigation. As the result of this study, it is possible to calculation a latitude, longitude, gravity and elevation at unknown point, and perphaps will be used as a fundamental data for application in the earth's crust structural analysis and geophysics.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.664-669
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• 2002

Intertidal zone (tidal flat) is a place which is sometimes dry and sometimes wet depending on the tidal rhythm. Direct measurement of topography in the intertidal zone is very difficult to be achieved. The interface between wet and dry parts in the tidal flat, which can be identified from near infrared band of satellite image, is a 'depth contour' which corresponds to the sea level at the time of satellite pass. Aquisition of topography data in tidal flat is possible by combining various techniques such as (1) identification of the interface between wet and dry parts, (2) GCP correction of satellite image, and (3) realtime prediction of sea level elevation at the time of satellite pass. The algorithm was successfully applied in obtaining topography (bathymetry) data in the intertidal zone of Asan Bay in the west coast of Korea from 26 satellite images. The method is expected to be very efficient in making bathymetry data base in the western and southern parts of Korea where tidal flats are well developed in wide regions.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.271-280
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• 1999

The topographical effect resulted from rugged terrains and inhomogeneous spectral characteristics due to the complexly mixed land cover condition of Korea substantially lower the remotely sensed land cover classification accuracy In this study, a topographic correction method using digital elevation model to alleviate the topographic effects. To deal with inhomogeneous spectral characteristic, a hybrid classifier with inclusion of prior probabilities was introduced. This investigation concluded that the topographical normalization and hybrid classification with prior probabilities are effective on rugged landscape. The overall and average classification accuracies were improved by 0.92％ and 1.016％ respectively. The most substantial and noticeable accuracy improvement was observed in forest areas.

• Journal of Chest Surgery
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• v.18 no.1
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• pp.128-139
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• 1985

Seven patients [six women and one man] with obstruction of hepatic portion of inferior vena cava was operated on, from May, 1969 to January, 1985. Of seven patients, six were undergone corrective operation for IVC obstruction and another one was not operated because of far advanced liver cirrhosis. The occlusions were found at or close to the level of diaphragm and they were membranous or diffuse with or without thrombi. Most of their symptoms were referable to either inferior vena caval or hepatic venous obstruction and onset of the symptoms was usually gradual, beginning between the age of their thirties and forties. Most of the patients showed marked elevation of peripheral venous pressure of lower extremity [29-40 cm H2O] preoperatively, which decreased significantly after corrective operation [17-30 cm H2O]. Venous catheterization for pressure study and venography were essential for confirming the diagnosis. Of six cases, in which corrective operations were done, Transatrial membranotomy with or without IVC dilatation were performed in five cases [case 1, 2, 3, 5, 6], using cardiopulmonary bypass and in another one case, bypass operation between IVC, distal to obstruction, and RA was done using Dacron tube graft under the thoracoabdominal incision. All survived and their conditions were improved.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1058-1060
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• 2003

A ground control point (GCP) is a point on the surface of Earth where image coord inates and map coordinates can be identified. The GCP is useful for the geometric correction of systematic and unsystematic errors usually contained in a remotely sensed data. Especially in case of synthetic aperture radar (SAR) data, it has serious geometric distortions caused by inherent side looking geometry. In addition, SAR images are usually severely corrupted by speckle noises so that it is difficult to identify ground control points. We developed a ground point extraction algorithm that has an improved capability. An application of radargrammetry to Daejon area in Korea was studied to acquire the geometric information. For the ground control point extraction algorithm, an ERS SAR data with precise Delft orbit information and rough digital elevation model (DEM) were used. We analyze the accuracy of the results from our algorithm by using digital map and GPS survey data.