• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.6
• /
• pp.62-71
• /
• 2013

The passive emitter location method using TDOA and FDOA measurements has higher accuracy comparing to the single TDOA or FDOA based method. Moreover, it is able to estimate the velocity vector of a moving platform. Recently, several non-iterative methods were suggested using the nuisance parameter but the common reference sensor is needed for each pair of sensors. They show also relatively low performance in the case of a long range between the sensor groups and the emitter. To solve this, we derive the estimation method of the position and velocity of a moving platform based on the Gauss-Newton method. In addition, to analyze the estimation performance of the position and velocity, respectively, we decompose the CRLB matrix into each subspace. Simulation results show the estimation performance of the derived method and the CEP planes according to the given geometry of the sensors.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.16 no.3
• /
• pp.103-114
• /
• 2013

In this study, we established the ortho mosaic imagery on the Korean Peninsula using KOMPSAT-2 images and conducted an accuracy assessment. Rational Polynomial Coefficient(RPC) modeling results were mostly less than 2 pixels except for mountainous regions which was difficult to select a Ground Control Point(GCP). Digital Elevation Model(DEM) which was made using the digital topographic map on the scale of 1:5,000 was used for generating an ortho image. In the case of inaccessible area, the Shuttle Radar Topography Mission(SRTM) DEM was used. Meanwhile, the ortho mosaic image of the Korean Peninsula was produced by each ortho image aggregation and color adjustment. An accuracy analysis for the mosaic image was conducted about a 1m color fusion image. In order to verify a geolocation accuracy, 813 check points which were acquired by field survey in South Korea were used. We found that the maximum error was not to exceed 5m(Root Mean Square Error : RMSE). On the other hand, in the case of inaccessible area, the extracted check points from a reference image were used for accuracy analysis. Approximately 69% of the image has a positional accuracy of less than 3m(RMSE). We found that the seam-line accuracy among neighboring image was very high through visual inspection. However, there were a discrepancy with 1 to 2 pixels at some mountainous regions.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.9
• /
• pp.1777-1787
• /
• 2017

Federated authentication (FA) is a multi-domain authentication and authorization infrastructure that enables users to access nationwide R&D resources with their home-organizational accounts. An FA-enabled user is redirected to his/her home organization, after selecting the home from an identity-provider (IdP) discovery service, to log in. The discovery service allows a user to search his/her home from all FA-enabled organizations. Users get troubles to find their home as federation size increases. Therefore, a discovery service has to provide an intuitive way to make a fast IdP selection. In this paper, we propose a discovery system which leverages geographical information. The proposed system calculates geographical proximity and text similarity between a user and organizations, which determines the order of organizations shown on the system. We also introduce a server redundancy and a status monitoring method for non-stop service provision and improved federation management. Finally, we deployed the proposed system in a real service environment and verified the feasibility of the system.

• Journal of the Korean earth science society
• /
• v.32 no.7
• /
• pp.832-859
• /
• 2011

The importance of scientific education on accurate oceanic currents and circulation has been increasingly addressed because the currents have played a significant role in climate change and global energy balance. The objectives of this study are to analyze errors of the oceanic current maps in the textbooks, to discuss a variety of error sources, to suggest how to produce a unified oceanic current map of the East Sea for the students. Twenty-seven textbooks based on the 7th National Curriculum were analyzed and quantitatively investigated on the characteristics of the current maps by comparing with both the previous literature and up-to-date scientific knowledge. All the maps in the textbooks with different mappings were converted to digitalized image data with Mercator mapping using geolocation information. Detailed analysis were performed to investigate the patterns of the Tsushima Warm Current (TWC) in the Korea Strait, to examine how closely the nearshore branch of the TWC flows along the Japanese coast, to scrutinize the features of the offshore branch of the TWC south of the subpolar front in the East Sea, to quantitatively investigate the northern range of the northward-propagating East Korea Warm Current and its latitude turning to the east, and lastly to examine the outflow of the TWC near the Tsugaru Strait and the Soya Strait. In addition, the origins, southern limits, and distances from the coast of the Liman Current and the North Korea Cold Current were analyzed. Other erroneous expressions of the currents in the textbooks were presented. These analyses revealed the problems in the present current maps of the textbooks, which might lead the students to misconception. This study also addressed a necessity in a bridge between scientists with up-to-date scientific results and educators who needed educational materials.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.18 no.4
• /
• pp.234-265
• /
• 2013

Oceanic current maps in the secondary school science and earth science textbooks have played an important role in piquing students's inquisitiveness and interests in the ocean. Such maps can provide students with important opportunities to learn about oceanic currents relevant to abrupt climate change and global energy balance issues. Nevertheless, serious and diverse errors in these secondary school oceanic current maps have been discovered upon comparison with up-to-date scientific knowledge concerning oceanic currents. This study presents the fundamental methods and strategies for constructing such maps error-free, through the unification of the diverse current maps currently in the textbooks. In order to do so, we analyzed the maps found in 27 different textbooks and compared them with other up-to-date maps found in scientific journals, and developed a mapping technique for extracting digitalized quantitative information on warm and cold currents in the East Sea. We devised analysis items for the current visualization in relation to the branching features of the Tsushima Warm Current (TWC) in the Korea Strait. These analysis items include: its nearshore and offshore branches, the northern limit and distance from the coast of the East Korea Warm Current, outflow features of the TWC near the Tsugaru and Soya Straits and their returning currents, and flow patterns of the Liman Cold Current and the North Korea Cold Current. The first draft of the current map was constructed based upon the scientific knowledge and input of oceanographers based on oceanic in-situ measurements, and was corrected with the help of a questionnaire survey to the members of an oceanographic society. In addition, diverse comments have been collected from a special session of the 2013 spring meeting of the Korean Oceanographic Society to assist in the construction of an accurate current map of the East Sea which has been corrected repeatedly through in-depth discussions with oceanographers. Finally, we have obtained constructive comments and evaluations of the interim version of the current map from several well-known ocean current experts and incorporated their input to complete the map's final version. To avoid errors in the production of oceanic current maps in future textbooks, we provide the geolocation information (latitude and longitude) of the currents by digitalizing the map. This study is expected to be the first step towards the completion of an oceanographic current map suitable for secondary school textbooks, and to encourage oceanographers to take more interest in oceanic education.

• Korean Journal of Remote Sensing
• /
• v.21 no.6
• /
• pp.445-456
• /
• 2005

The land surface parameters should be determined with sufficient accuracy, because these play an important role in climate change near the ground. As the surface reflectance presents strong anisotropy, off-nadir viewing results a strong dependency of observations on the Sun - target - sensor geometry. They contribute to the random noise which is produced by surface angular effects. The principal objective of the study is to provide a database of accurate surface reflectance eliminated the angular effects from MODIS 250m reflective channel data over Korea. The MODIS (Moderate Resolution Imaging Spectroradiometer) sensor has provided visible and near infrared channel reflectance at 250m resolution on a daily basis. The successive analytic processing steps were firstly performed on a per-pixel basis to remove cloudy pixels. And for the geometric distortion, the correction process were performed by the nearest neighbor resampling using 2nd-order polynomial obtained from the geolocation information of MODIS Data set. In order to correct the surface anisotropy effects, this paper attempted the semiempirical kernel-driven Bi- directional Reflectance Distribution Function(BRDF) model. The algorithm yields an inversion of the kernel-driven model to the angular components, such as viewing zenith angle, solar zenith angle, viewing azimuth angle, solar azimuth angle from reflectance observed by satellite. First we consider sets of the model observations comprised with a 31-day period to perform the BRDF model. In the next step, Nadir view reflectance normalization is carried out through the modification of the angular components, separated by BRDF model for each spectral band and each pixel. Modeled reflectance values show a good agreement with measured reflectance values and their RMSE(Root Mean Square Error) was totally about 0.01(maximum=0.03). Finally, we provide a normalized surface reflectance database consisted of 36 images for 2001 over Korea.