• Journal of Korean Society for Geospatial Information Science
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• v.24 no.1
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• pp.3-8
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• 2016

Due to the recent technical development and the enhancement of image resolution, Unmanned Airborne Vehicles(UAVs) have been used for various fields. A low altitude UAV system takes advantage of taking riverbed imagery at small rivers as well as land surface imagery on the ground. The bathymetric data are generated from the low altitude UAV system. The accuracy of the data is analyzed along water depths, comparing GPS observations and a DSM generated from UAV images. It is found that the depth accuracy of the geospatial data below 50 cm depth of water satisfies the regulation(${\pm}10cm$ spatial accuracy) of bathymetric surveying. Therefore this research shows that the geospatial data generated from UAV images at shallow regions of rivers can be used for bathymetric surveying.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1433-1443
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• 1993

DCT(Discrete Cosine Transform) / IDCT(Inverse DCT) is widely used in various image compression and decompression systems as well as in DSP(Digital Signal Processing) applications. Since DCT/ IDCT is one of the most complicated part of the compression system, the performance of the system can be greatly enchanced by improving the speed of DCT/IDCT operation. In this thesis, we designed a DCT/IDCT core processor using module generator technique. By utilizing the partial sum and DA(Distributed Arithmetic) techniques, the DCT/ IDCT core processor is designed within small area. It is also designed to perform the IDCT(Inverse DCT) operation with little additional circuitry. The pipeline structure of the core processor enables the high performance, and the high accuracy of the DCT/IDCT operation is obtained by having fewer rounding stages. The proposed design is independent of design rules, and the number of the input bits and the accuracy of the internal calculation coa be easily adjusted due to the module generator technique. The accuracy of the processor satisfies the specifications in CCITT recommendation H, 261.

• Journal of Korea Multimedia Society
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• v.21 no.4
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• pp.450-463
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• 2018

Sound based machine fault diagnosis is the process consisting of detecting automatically the damages that affect the machines by analyzing the sounds they produce during their operating time. The collected sounds being inevitably corrupted by random disturbance, the most important part of the diagnosis consists of discovering the hidden elements inside the data that can reveal the faulty patterns. This paper presents a novel feature extraction methodology that combines various digital signal processing and pattern recognition methods for the analysis of the sounds produced by the drills. Using the Fourier analysis, the magnitude spectrum of the sounds are extracted, converted into two-dimensional vectors and uniformly normalized in such a way that they can be represented as 8-bit grayscale images. Histogram equalization is then performed over the obtained images in order to adjust their very poor contrast. The obtained contrast enhanced images will be used as the features of our diagnosis system. Finally, principal component analysis is performed over the image features for reducing their dimensions and a nonlinear classifier is adopted to produce the final response. Unlike the conventional features, the results demonstrate that the proposed feature extraction method manages to capture the hidden health patterns of the sound.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.601-611
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• 2011

The paper deals with the selection of 3D display devices in accordance with the user's conveniences and accuracy of spatial information by applying 3D display devices to Spatial Information Update System (SIUS) which generate edit and update digital thematic maps. After applying different manufacturer's 3D display devices to SIUS, aerial images acquired from the stereo images were displayed through the devices and spatial information was extracted from the displayed 3D images. Assessment of 3D display devices were based on quantitative and qualitative analysis on accuracy of spatial information and user's conveniences. Planar's PL2020 and Redrover's Tru3Di 3D monitor has expressed outstanding display environment in 3D related tasks for the generation of spatial information compared to other 3D display devices. System improvement is expected regarding accuracy of spatial information, work efficiency and user's conveniences.

• Korean Journal of Remote Sensing
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• v.31 no.2
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• pp.183-191
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• 2015

If the damage analysis on river-side facilities such as dam, river bank structures and bridges caused by disasters such as typhoon, flood, etc. becomes available, it can be a great help for disaster recovery and decision-making. In this research, We tried to extract a Digital Surface Model (DSM) and analyze the accuracy from Unmanned Air Vehicle (UAV) images on river-side facilities. We tried to apply stereo image-based matching technique, then extracted match results were united with one mosaic DSM. The accuracy was verified compared with a DSM derived from LIDAR data. Overall accuracy was around 3m of absolute and root mean square error. As an analysis result, we confirmed that exterior orientation parameters exerted an influence to DSM accuracy. For more accurate DSM generation, accurate EO parameters are necessary and effective interpolation and post process technique needs to be developed. And the damage analysis simulation with DSM has to be performed in the future.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.344-350
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• 2014

Multi Function Display(MFD) of Korean Utility Helicopter(KUH) is the component of mission management/display control system and displays image information(navigation, flight, survivability, digital map, maintenance) acquired from Mission Computer(MC) while the aircraft is operated. It is an essential equipment for pilots to perform flight mission and it has functions of display scene control, data display, built in test(BIT) and brightness control. In this paper, it is analyzed the cause of abnormal display(flickering) on MFD and summarized the design changes to solve the defect. It is also described system safety analysis and suggested verification results of flight/ground test.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.3
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• pp.109-114
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• 2009

Although island is great worth in ecology, environmental conservation and important territory as a national land for developing the marine, the bottom of the sea and also ecological studying field for the ages to come, it has not been managed because of lack of a scientific surveying. In the case of a cadastral record, inaccessible islands have not been registered in current cadastral record because of the limit of surveying technology in 1910. Therefore, a scientific investigation and systematic management about unregistered islands are necessary. But, a airborne laser scanning system is possible to acquire an accurate positions with digital images about inaccessible islands. Therefore, scientific detection of unregistered islands became possible. This paper presented the results of the shoreline extraction around the Heuksan island using Lidar data and the detection of unregistered islands comparing the cadastral map to the ortho-image. Also, we presented the extraction technique of unregistered islands by calculating their positions and areas. As a result, we extracted effectively 16 unregistered islands around the Heuksan island.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.389-395
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• 2012

U-City has been promoted nation-wide by development of recent IT technology. This paper studied the concept of 3D-virtual city in order to realize the current Ubiquitous City(U-City) efficiently, and to manage all the RFID/USN monitoring data in the real U-City. 3D-Virtual City is the concept of the reproduction of real world U-City, for embodying Ubiquitous technology while using Digital map, satellite image, VRML(Virtual Reality Modeling Language). U&V-City is the four-dimensional future city that real-time wire/wireless communication network and 3D-web GIS shall be connected that massive database, intelligent service be perceived through employing EAI(External Authoring Interface) that provides HTML&JAVA, and interface for efficient removal/process of massive information/ service and also by employing GPS/LBS/Navigation in support of world-wide orientation concept, and RTLS(Real Time Location System).

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.825-830
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• 2010

Generally, the copy protection mark and 2D bar-code techniques are widely used for forgery protection in printed public documents. But, it is hard to discriminate truth from the copy documents by using exisiting methods, because of that existing 2D-barcode is separated from the copy protection mark and it can be only recognized by specified optical barcord scanner. Therefor, in this paper, we proposed the forgery protection tehchnique for discriminating truth from the copy document by using watermark inserted 2D-barcord, which can be accurately distinguished not only by naked eye, but also by scanner. The copy protection mark consists of deformed patterns that are caused by the lowpass filter characteristic of digital I/O device. From these, we verified the performance of the proposed techniques by applying the histogram analysis based on the original, copy, and scanned copy image of the printed documents. Also, we suggested 2D-barcord confirmation system which can be accessed through the online server by using certification key data which is detected by web-camera, cell phone camera.

• Imaging Science in Dentistry
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• v.45 no.3
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• pp.175-180
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• 2015

Purpose: This study was performed to evaluate the reliability of the identification of anatomical landmarks in panoramic and lateral cephalometric radiographs on a standard medical grade picture archiving communication system (PACS) monitor and a tablet computer (iPad 5). Materials and Methods: A total of 1000 radiographs, including 500 panoramic and 500 lateral cephalometric radiographs, were retrieved from the de-identified dataset of the archive of the Section of Oral and Maxillofacial Radiology of the University Of Connecticut School Of Dental Medicine. Major radiographic anatomical landmarks were independently reviewed by two examiners on both displays. The examiners initially reviewed ten panoramic and ten lateral cephalometric radiographs using each imaging system, in order to verify interoperator agreement in landmark identification. The images were scored on a four-point scale reflecting the diagnostic image quality and exposure level of the images. Results: Statistical analysis showed no significant difference between the two displays regarding the visibility and clarity of the landmarks in either the panoramic or cephalometric radiographs. Conclusion: Tablet computers can reliably show anatomical landmarks in panoramic and lateral cephalometric radiographs.