• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.2
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• pp.109-115
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• 2011

As fingerprinting method, k-nearest neighbor(KNN) has been widely applied for indoor location in wireless location area networks(WLAN), but its performance is sensitive to number of neighbors k and positions of reference points(RPs). So artificial neural network(ANN) clustering algorithm is applied to improve KNN, which is the KNN/ANN hybrid algorithm presented in this paper. For any pattern matching based algorithm in WLAN environment, the characteristics of signal to noise ratio(SNR) to multiple access points(APs) are utilized to establish database in the training phase, and in the estimation phase, the actual two dimensional coordinates of mobile unit(MU) are estimated based on the comparison between the new recorded SNR and fingerprints stored in database. In the proposed algorithm, through KNN, k RPs are firstly chosen as the data samples of ANN based on SNR. Then, the k RPs are classified into different clusters through ANN based on SNR. Experimental results indicate that the proposed KNN/ANN hybrid algorithm generally outperforms KNN algorithm when the locations error is less than 2m.

• Journal of Advanced Navigation Technology
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• v.14 no.2
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• pp.151-160
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• 2010

For the realization of future intelligent transportation systems, fine-grained lane-by-lane traffic monitoring and control functionalities are among the most important technology barriers to overcome. To satisfy the accuracy requirement for traffic monitoring, a GNSS receiver network is designed. The designed receiver network consists of three different types of entities; reference server, broadcaster, and client. For deployment flexibility, all the entities utilize the international message standard RTCM SC-104 version 3.0. For fine-grained traffic monitoring, the client is designed to utilize position-domain carrier-smoothed-code filters to provide accurate vehicle coordinates in spite of frequent addages and outages of visible satellites. An experiment result is presented to evaluate the positioning accuracy of the proposed method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.6_1
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• pp.575-581
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• 2012

In general, various modeling and estimation techniques have been proposed to extract the tropospheric and ionospheric delays from the GPS CORS. In this study, Kalman filter approach is adopted to estimate the tropospheric and ionospheric delays and the proper modeling for the state vector and the variance-covariance matrix for the process noises are performed. The coordinates of reference stations and the zenith wet delays are estimated with the assumption of random walk stochastic process. Also, the first-order Gauss-Markov stochastic process is applied to compute the ionospheric effects. For the evaluation of the proposed modeling technique, Kalman filter algorithm is implemented and the numerical test is performed with the CORS data. The results show that the atmospheric effects can be estimated successfully and, as a consequence, can be used for the generation of VRS data.

• Korean Journal of Environmental Biology
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• v.38 no.3
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• pp.424-432
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• 2020

The present study aimed to analyze the metaproteome of the microbial community comprising harmful algal bloom (HAB) in the Daechung reservoir, Korea. HAB samples located at GPS coordinates of 36°29'N latitude and 127°28'E longitude were harvested in October 2013. Microscopic observation of the HAB samples revealed red signals that were presumably caused by the autofluorescence of chlorophyll and phycocyanin in viable cyanobacteria. Metaproteomic analysis was performed by a gelbased shotgun proteomic method. Protein identification was conducted through a two-step analysis including a forward search strategy (FSS) (random search with the National Center for Biotechnology Information (NCBI), Cyanobase, and Phytozome), and a subsequent reverse search strategy (RSS) (additional Cyanobase search with a decoy database). The total number of proteins identified by the two-step analysis (FSS and RSS) was 1.8-fold higher than that by one-step analysis (FSS only). A total of 194 proteins were assigned to 12 cyanobacterial species (99 mol%) and one green algae species (1 mol%). Among the species identified, the toxic microcystin-producing Microcystis aeruginosa NIES-843 (62.3%) species was the most dominant. The largest functional category was proteins belonging to the energy category (39%), followed by metabolism (15%), and translation (12%). This study will be a good reference for monitoring ecological variations at the meta-protein level of aquatic microalgae for understanding HAB.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.2
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• pp.299-309
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• 1998

The national coordinate system is an essential component for a geographic/land information system, since it provides the spatial reference for expressing position information. The national mapping of Korea has been based on 3-different meridians on the Gauss-Schreiber projection in year 1910s, later this was changed to the Gauss-Kruger projection. Existing map coordinate systems maintaining the national land survey project on 1910s, have some structural shortcomings of unknown computational procedures and projection methods. In this paper, the problems of the map coordinates usage and of longitudes origin shift(10.405") and their solutions are investigated. Also, this study discusses the issues involved in choosing coordinate system for digital mapping and their applications as a basis for spatial data management. The foreign country's coordinate systems are reviewed and the elements to realize a new unified grid coordinate system is proposed. The Transverse Mercator projection with a central meridian of $127^\circ\;30'$, scale factor 0.9996, and GRS80 ellipsoid, is selected in Korean peninsula.sula.

• Economic and Environmental Geology
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• v.29 no.3
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• pp.369-380
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• 1996

In order to determine the emplacement time and stratigraphic position of basaltic rocks in the central part of Pohang basin, palaeomagnetic investigations were conducted on 111 samples collected from 6 sites. Formation mean built from site-mean ChRM directions is $d=340.7^{\circ}$, $i=52.2^{\circ}$ (${\alpha}_{95}=6.0^{\circ}$, k=91) in the geographic coordinates. If "tilt" correction is applied regarding the plane perpendicular to the side walls of columnar joint as palaeohorizon, the formation mean becomes $d=328.7^{\circ}$, $i=43.8^{\circ}$ (${\alpha}_{95}=17.1^{\circ}$, k=13). It is to be noticed that the formation mean is deflected significantly (about $20{\sim}30^{\circ}$) counterclockwise from the Tertiary reference geomagnetic field of Eurasia, independent of "tilt" correction. This situation is very different from that of clockwise rotation of ChRM directions which has been ubiquitously observed in other Tertiary basins of south Korea, and indicates sinistral regional simple-shearing during the emplacement times of the basaltic rocks. Considering previous palaeomagnetic and AMS (anisotropy of magnetic susceptibility) data from other Tertiary regions of south Korea, the time of this sinistral shearing should be 15 Ma or directly thereafter, and this time point represents inversion from extensional to compressional tectonic regime. Magnetic foliation data obtained in this study indicate WNW-ESN compression during or directly after emplacement of the basaltic rocks, while it has known from regional tectonic study that the time of the WNW-ESN compression is about 15 Ma, when SW Honshu was rotated and the Korean strait was narrowed.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.126-133
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• 2004

Photogrammetry, as its name implies, is a 3-dimensional coordinate measuring technique that uses photographs as the fundamental medium for metrology. In the last few years the accuracy of photogrammetry has increased dramatically thanks to the rapid advance of digital camera manufacturing technique. This paper discusses photogrammetric measurement of the interface surface of MSC(Multi-Spectral Camera), which is a main payload of KOMPSAT-2. Total 24 paper targets on the objective surfaces and two scale bars calibrated with high accuracy were used for measurement, and multiple images were taken from 11 different camera angles by using a spacecraft rotation dolly. As a result of analysis, 3D coordinates of each targeted point were obtained and the flatness value based on the selected reference plane was calculated and compared with the pre-determined requirement. The technique acquired by this study is expected to be used for the 3D precise measurement of ultra-light weight and inflatable space structures such as a satellite antenna and a solar array.

• The KIPS Transactions:PartB
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• v.17B no.3
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• pp.215-226
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• 2010

The structured-light 3D reconstruction technique uses a coded-pattern to find correspondences between the camera image and the projector image. To calculate the 3D coordinates of the correspondences, it is necessary to calibrate the camera and the projector. In addition, the calibration results affect the accuracy of the 3D reconstruction. Conventional camera-projector calibration techniques commonly require either expensive hardware rigs or complex algorithm. In this paper, we propose an easy camera-projector calibration technique. The proposed technique does not need any hardware rig or complex algorithm. Thus it will enhance the efficiency of structured-light 3D reconstruction. We present two camera-projector systems to show the calibration results. Error analysis on the two systems are done based on the projection error of the camera and the projector, and 3D reconstruction of world reference points.

• The Journal of Korean Institute of Information Technology
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• v.16 no.12
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• pp.49-56
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• 2018

As the era of the 4th industrial revolution comes, there is a growing interest in the use of UAVs. While various technologies are being developed using drones, controlling flight of drones is the most basic. Hovering control is essential in order to enable autonomous flight, especially during flight control of drones. In this paper, we design drones based on ATmega2560, Sonar, Optical Flow, and acceleration / gyro 6 axis sensor for drones hovering control, and developed horizontal control, altitude control, position tracking and fixed algorithm based on PID control. In this research, in order to measure the objective result of the drone, keeping the altitude immediately after the drone takes off according to the time, measure the movement value until the position is fixed and stable hovering is maintained and compared analyzed. Experimental results show that the drones can stably hover within 4cm horizontal and 2cm vertical from 50cm above the reference coordinates.

• Journal of the Korea Society of Computer and Information
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• v.24 no.1
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• pp.73-83
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• 2019

In this paper, we propose the augmented reality(AR) based driving navigation based on robust lane detection method to dynamic environment changes. The proposed technique uses the detected lane position as a marker which is a key element for enhancing driving information. We propose Symmetrical Local Threshold(SLT) algorithm which is able to robustly detect lane to dynamic illumination environment change such as shadows. In addition, by using Morphology operation and Connected Component Analysis(CCA) algorithm, it is possible to minimize noises in the image, and Region Of Interest(ROI) is defined through region division using a straight line passing through several vanishing points We also propose the augmented reality aided visualization method for Interchange(IC) and driving navigation using reference point detection based on the detected lane coordinates inside and outside the ROI. Validation experiments were carried out to assess the accuracy and robustness of the proposed system in vairous environment changes. The average accuracy of the proposed system in daytime, nighttime, rainy day, and cloudy day is 79.3% on 4600 images. The results of the proposed system for AR based IC and driving navigation were also presented. We are hopeful that the proposed research will open a new discussion on AR based driving navigation platforms, and thus, that such efforts will enrich the autonomous vehicle services in the near future.