• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.281-286
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• 2006

In this study, acquired time series Landsat TM/ETM+ image to extract land surface temperature for wide-area region and executed geometric correction and radiometric correction. And extracted land surface temperature using NASA Model, and I achieved the first correction by perform land coverage category for study region and applies characteristic emission rate. Land surface temperature that acquire by the first correction analyzed correlation with Meteorological Administration's temperature data by regression analysis, and established correction formula. And I wished to improve accuracy of land surface temperature extraction using satellite image by second correcting deviations between two datas using establishing correction formula. As a result, land surface temperature that acquire by 1,2th correction could correct in mean deviation of about ${\pm}3.0^{\circ}C$ with Meteorological Administration data. Also, could acquire land surface temperature about study region by relative high accuracy by applying to other Landsat image for re-verification of study result.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.137-141
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• 2006

To consider the practical use of a ship's Digital Compass in earth's magnetic field high accurate Deviation and 얘 nation are required to obtain ship's true bearing. Variation can be obtain with World Magnetic Model (WMM) using the Earth's spherical harmonic model of the main field and of the secular variation at any location around the earth. Deviation can be obtain with deviation analysis and synthesis method based on the Poisson equations. As results of deviation and variation corrections to the Digital Compass, high accurate true bearing is obtained. This experiments are carried out during in the navigation of training ship 'SAE-NU-RI'.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.4
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• pp.319-327
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• 2004

The Electronic compass made as a pilot model in this research is comprised of a three axis magnetic sensor, an accustar clinometer, and a fiber optic gyro sensor. The results confirming the output character, performance, and the accuracy of the deviation corrects of each sensor are as follows: 1) As for the output character of the three axis magnetic sensor, the magnetic field showed a cosine curve on the X axis, a - sine curve on the Y axis, and constant figures on the Z sensor. The horizontal component H and the vertical component V of the terrestrial magnetism calculated from the output voltage were 33.2${\mu}$T and 23.95${\mu}$T respectively. 2) When the fiber optic gyro sensor is fixed on the electromotive rotation transformation and has made a clockwise rotation with the speed of 10/sec, 20/sec, and 30/sec, the relationship between the output and the rotation angle of the fiber optic gyro sensor showed proportionally constant values. 3) When the magnetic field was induced with a magnet, the deviation before the correction was significant at a high of 25. However, the deviation after the correction using Poisson correction was in the 2 range, significantly lower than before the correction. It was confirmed that automatic deviation corrects are possible with the electronic compass made as a pilot model in this research.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.2
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• pp.97-104
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• 2015

Due to the introduction of various IT devices, including the recently smartphones and the widespread use of the car navigation system to the location-based information service space has been increased. Spatial information users have been requiring higher levels of quality. In this paper, we study how to build accurate three-dimensional space information by integrating MMS(Moblie Mapping System) survey and airborne survey data. Thus, to analyze the tendency of deviation between the MMS survey and airborne survey data observed in the experimental region, the deviation tendency of the data, it was confirmed that was not consistent. Deviation correction model to select how to change the georeferencing information directly contained in the GPS/INS processing results for the determination, classifies the standard is a method for acquiring the correction reference point coordinates using the calibration model, and analyzed their advantages and disadvantages. With the information of the reference point obtained by airborne photograph of a project, using the method of correcting the MMS survey data. Not only clear the deviation existing between the MMS survey data, it was possible to confirm that the deviation exists between the airborne survey data and MMS survey data was also almost erased.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.120-120
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• 2020

Spatial precipitation data is one of the essential components in modeling hydrological problems. The estimation of these data has achieved significant achievements own to the recent advances in remote sensing technology. However, there are still gaps between the satellite-derived rainfall data and observed data due to the significant dependence of rainfall on spatial and temporal characteristics. An effective approach based on the Convolutional Neural Network (CNN) model to correct the satellite-derived rainfall data is proposed in this study. The Mekong River basin, one of the largest river system in the world, was selected as a case study. The two gridded precipitation data sets with a spatial resolution of 0.25 degrees used in the CNN model are APHRODITE (Asian Precipitation - Highly-Resolved Observational Data Integration Towards Evaluation) and PERSIANN-CDR (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks). In particular, PERSIANN-CDR data is exploited as satellite-based precipitation data and APHRODITE data is considered as observed rainfall data. In addition to developing a CNN model to correct the satellite-based rain data, another statistical method based on standard deviations for precipitation bias correction was also mentioned in this study. Estimated results indicate that the CNN model illustrates better performance both in spatial and temporal correlation when compared to the standard deviation method. The finding of this study indicated that the CNN model could produce reliable estimates for the gridded precipitation bias correction problem.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.4
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• pp.95-106
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• 2013

It is now generally known that dynamical climate modeling outputs include systematic biases in reproducing the properties of atmospheric variables such as, preciptation and temerature. There is thus, general consensus among the researchers about the need of bias-correction process prior to using climate model results especially for hydrologic applications. Among the number of bias-correction methods, distribution (e.g., cumulative distribution fuction, CDF) mapping based approach has been evaluated as one of the skillful techniques. This study investigates the uncertainty of using various CDF mapping-based methods for bias-correciton in assessing regional climate change Impacts. Two different dynamicailly-downscaled Global Circulation Model results (CCSM and GFDL under ARES4 A2 scenario) using Regional Spectial Model for retrospective peiod (1969-2000) and future period (2039-2069) were collected over the west central Florida. Total 12 possible methods (i.e., 3 for developing distribution by each of 4 for estimating biases in future projections) were examined and the variations among the results using different methods were evaluated in various ways. The results for daily temperature showed that while mean and standard deviation of Tmax and Tmin has relatively small variation among the bias-correction methods, monthly maximum values showed as significant variation (~2'C) as the mean differences between the retrospective simulations and future projections. The accuracy of raw preciptiation predictions was much worse than temerature and bias-corrected results appreared to be more significantly influenced by the methodologies. Furthermore the uncertainty of bias-correction was found to be relevant to the performance of climate model (i.e., CCSM results which showed relatively worse accuracy showed larger variation among the bias-correction methods). Concludingly bias-correction methodology is an important sourse of uncertainty among other processes that may be required for cliamte change impact assessment. This study underscores the need to carefully select a bias-correction method and that the approach for any given analysis should depend on the research question being asked.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.2
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• pp.159-172
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• 2006

In this study, the series of Landsat TM/ETM+ images was acquired to extract land surface temperature for wide-area and executed geometric correction and radiometric correction. And the land surface temperature was extracted using NASA Model, and achieved the first correction by performing land coverage category for study area and applied characteristic emission rate. Land surface temperature which was acquired by the first correction was analyzed in correlation with Meteorological Administration's temperature data by regression analysis, and established correction formula. And I wished to improve accuracy of land surface temperature extraction using satellite image by second correcting deviations between two data using establishing correction formula. As a result, land surface temperature acquired by 1st and 2st correction could be corrected in mean deviation of about ${\pm}3.0^{\circ}C$ with Meteorological Administration data. Also, I could acquire land surface temperature about study area by higher accuracy by applying to other Landsat images for re-verification of study results.

• Transactions of Materials Processing
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• v.29 no.4
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• pp.188-193
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• 2020

Piping work of large ships or offshore plants is often done in a narrow and confined space, requiring precise bending and safety. In order to realize an accurate bending angle, it is very important to predict and correct a deformation that may be caused by elasticity in the bending process, that is, an angular deviation due to springback. Therefore, by using CAE analysis to develop a correction angle model for springback based on multiple tube bending angles and using trend line data derived from this correction angle model, at bending the tube as the diameter of the base former and the tube outer diameter change, the springback compensation angle at any angle can be obtained. In this study, the bending mechanism was analyzed to increase the bending precision, and a correction angle model was developed and a trend line was derived in consideration of springback occurring in the bending process. In order to derive a more accurate and reliable trend line, a tube tensile test was performed, and the reliability of the corrected angle trend line was verified by comparing the bending angle measurement and analysis results with a 3D scanner.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.4
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• pp.385-392
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• 2005

This paper describes an accuracy analysis of newly developed gravimetric geoid and an improvement of developed geoid using GPS/Levelling data. We developed the KGEOID05 model corrected with the correction term. The correction term is modelled using the difference between GPS/Levelling derived geoidal heights and gravimetric geoidal heights. The stochastic model used in the calculation of correction term is the least squares collocation technique based on second-order Markov covariance function. 373 GPS stations were used to model the correction term. The standard deviation of KGEOID05 is about 11 cm and it indicates that we can be determined accurate heights ($2{\sim}3\;cm$) when we made precise modelling using KGEOID05 and a few GPS measurements for the local area.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.12
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• pp.1232-1237
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• 2009

The ICAO and FAA are developing and verifying of GBAS for civil aircraft landing and take-off. The guarantee of aircraft integrity issue is the important part of GBAS. To guarantee integrity, the GBAS ground facility broadcasts various informations to aircraft. The informations are related to the estimated accuracy of each pseudorange correction and the estimated error terms, for example B-value and standard deviation of the ground facility error. These parameters are used to calculate position error (estimated value of the user). If estimated position errors don't satisfy requirements, aircraft use alternate navigation means. In this paper, GBAS reference stations's real data, which operated by KARI (Korea Aerospace Research Institute) in Jeju international airport, are used to development of new ground facility error standard deviation model. We verify improvement of GBAS availability, with respected to vertical protection level, using B-value based a new ground facility error standard deviation model and a sigma inflation factor.