• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.270-270
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• 2017

스마트워터그리드와 같은 첨단 정보통신기술을 활용한 물 관리 기술의 도입으로 수도운영사업에서도 누수와 같은 이상사건인지 목적의 효율적 빅 데이터 분석기법의 중요성이 증대되고 있다. 국내외적으로 누수인지를 위한 다양한 연구기법, 범위, 계측항목, 샘플링 주기 등이 제시된 바 있으나, 이상감지시스템(Event Detection System, EDS)은 대상지역 특정적 특성을 가지고 있어 범용적인 모델을 구축하는 데는 어려움이 있다. 본 연구에서는 소블럭 단위의 유량자료 분석을 통한 이상감지시스템의 적용가능여부를 판별하고 적합 모델구축자료 방안을 제시하는 K-EDS 모델을 개발하였다. 모델분석의 절차는 자료획득, 자료 전처리, 탐색적 자료해석, 그리고 각 기법 평가로 진행된다. 개발된 모델을 다양한 특성을 가지는 실제 지방상수도시스템에 적용하여 분석하였으며, 최종적으로 모델적용 가능성과 영향인자 등을 도출하였다. 개발된 모델은 소블럭별 현장계측자료 기반의 이상감지모델 적용 적합도 판별에 활용될 수 있으며, 향후 누수 인지 및 누수지속시간 감소를 위한 SW로 개발이 가능하다.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.167-172
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• 2006

An image retrieval system retrieves and offers same of similar image based on various features of image. This paper present a brand image retrieval system based on color and shape of image. We use the image for a color information by dividing into the area and extracting the area color distribution histogram. We use for the shape information by preprocessing of the boundary extraction, the centroid extraction, angular sampling etc. and calculating of the sum of the distance from the centroid to the boundary, the standard deviation, and the rate of long axis to short axis. We accomplish the retrieval through a similarity measurement by using the color and shape information which is extracted in this way.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1231-1244
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• 2022

The frequency of exposure of field crops to stress situations is increasing due to abnormal weather conditions. In South Korea, large-scale diseases in representative paddy rice cultivation area were happened. There are limits to field investigation on the crop damage due to large-scale. Satellite-based remote sensing techniques are useful for monitoring crops in cities and counties, but the sensitivity of vegetation index measured from satellite under abnormal growth of crop should be evaluated. The goal is to evaluate satellite-based normalized difference vegetation index (NDVI) retrieved from different spatial scales using drone imagery. In this study, Sentinel-2 and Landsat-8 satellites were used and they have spatial resolution of 10 and 30 m. Drone-based NDVI, which was resampled to the scale of satellite data, had correlation of 0.867-0.940 with Sentinel-2 NDVI and of 0.813-0.934 with Landsat-8 NDVI. When the effects of bias were minimized, Sentinel-2 NDVI had a normalized root mean square error of 0.2 to 2.8% less than that of the drone NDVI compared to Landsat-8 NDVI. In addition, Sentinel-2 NDVI had the constant error values regardless of diseases damage. On the other hand, Landsat-8 NDVI had different error values depending on degree of diseases. Considering the large error at the boundary of agricultural field, high spatial resolution data is more effective in monitoring crops.

• Journal of Korea Multimedia Society
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• v.14 no.6
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• pp.835-848
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• 2011

In this paper, we propose a client server based distributed/parallel system to effectively visualize huge geographic data. The system consists of a web-based client GUI program and a distributed/parallel server program which runs on multiple PC clusters. To make the client program run on mobile devices as well as PCs, the graphical user interface has been designed by using JOGL, the java-based OpenGL graphics library, and sending the information about current available memory space and maximum display resolution the server can minimize the amount of tasks. PC clusters used to play the role of the server access requested geographic data from distributed disks, and properly re-sample them, then send the results back to the client. To minimize the latency happened in repeatedly access the distributed stored geography data, cache data structures have been maintained in both every nodes of the server and the client.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.4
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• pp.335-342
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• 2012

3D point cloud is widely used in Architecture, Civil Engineering, Medical, Computer Graphics, and many other fields. Due to the improvement of 3D laser scanner, a massive 3D point cloud whose gigantic file size is bigger than computer's memory requires efficient preprocessing and visualization. We suggest a data structure to solve the problem; a 3D point cloud is gradually subdivided by arbitrary-sized cube grids structure and corresponding point cloud subsets generated by the center of each grid cell are achieved while preprocessing. A massive 3D point cloud file is tested through two algorithms: QSplat and ours. Our algorithm, grid-based, showed slower speed in preprocessing but performed faster rendering speed comparing to QSplat. Also our algorithm is further designed to editing or segmentation using the original coordinates of 3D point cloud.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.147-155
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• 2013

The nominal radiometric calibration equation and additional five algorithms are applied in the infrared channel radiometric calibration for the COMS (Communication, Ocean, Meteorological Satellite) MI (Meteorological Imager). The processing end time of the radiometric calibration is directly related with the start time of geometric calibration processing since the geometric calibration processing is followed by that of the radiometric calibration. This paper describes comparison and analysis results for geometric calibration processing using two types of the radiometric calibration results, outputs from only the nominal radiometric calibration equation and outputs from the complete one (the nominal radiometric calibration equation with additional five algorithms), to propose a method with the earlier start time of the geometric calibration processing. Experimental results show that both of radiometric calibration results, from the nominal radiometric calibration equation with a fast processing speed and from the complete one with accurate radiometric values, can be used in the geometric calibration as the appropriate inputs because those processing results satisfied the requirements of geometric calibration processing accuracy. Thus the radiometric calibration results from the nominal radiometric calibration equation can be used to improve geometric calibration processing time.

• Journal of Broadcast Engineering
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• v.13 no.3
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• pp.299-309
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• 2008

In this paper, we propose an algorithm for object generation from model-based 3-dimensional multi-viewpoint images using OpenGL rendering. In the first step, we preprocess a depth map image in order to get a three-dimensional coordinate which is sampled as a vertex information on OpenGL and has a z-value as depth information. Next, the Delaunay Triangulation algorithm is used to construct a polygon for texture-mapping using the vertex information. Finally, by mapping a texture image on the constructed polygon, we generate a viewpoint-adaptive object by calculating 3-dimensional coordinates on OpenGL.

• Journal of Korea Game Society
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• v.17 no.6
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• pp.113-120
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• 2017

With the development of virtual reality technology, in recent years, user-friendly hand gesture interface has been more studied for natural interaction with a virtual 3D object. Most earlier studies on the hand-gesture interface are using relatively simple hand gestures. In this paper, we suggest an intuitive hand gesture interface for interaction with 3D object in the virtual reality applications. For hand gesture recognition, first of all, we preprocess various hand data and classify the data through the binary decision tree. The classified data is re-sampled and converted to the chain-code, and then constructed to the hand feature data with the histograms of the chain code. Finally, the input gesture is recognized by MCSVM-based machine learning from the feature data. To test our proposed hand gesture interface we implemented a 'Virtual Block' game. Our experiments showed about 99.2% recognition ratio of 16 kinds of command gestures and more intuitive and user friendly than conventional mouse interface.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.115-123
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• 2002

In this paper, we present two types of vision algorithm that mobile robot has CCD camera. for obstacle avoidance and path plan. One is simple algorithm that compare with grey level from input images. Also, The mobile robot depend on image processing and move command from PC host. we has been studied self controlled mobile robot system with CCD camera. This system consists of TMS320F240 digital signal processor, step motor, RF module and CCD camera. we used wireless RF module for movable command transmitting between robot and host PC. This robot go straight until 95 percent filled screen from input image. And the robot recognizes obstacle about 95 percent filled something, so it could avoid the obstacle and conclude new path plan. Another is complex algorithm that image preprocessing by edge detection, converting, thresholding and image processing by labeling, segmentation, pixel density calculation.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.51-51
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• 2017

지역빈도해석은 짧은 기간의 자료를 보유하고 있는 계측 지점이나 자료가 없는 미계측 지점에서의 확률수문량을 산정하기 위하여 많이 쓰여 진다. 지역빈도해석을 실시하기 위한 조건으로는 우선 수집된 하천유역들을 대상으로 수문학적 동질 지역을 구분하는 것이 중요하다. 그리고 구분되어진 지역에 포함되는 모든 지점들의 자료를 빈도해석 함으로써 관심 지점의 신뢰할 만한 확률수문량을 산정하는 것이다. 그동안의 지역빈도해석은 주로 비건조지역을 중심으로 홍수와 같은 재난재해 대비 그리고 수자원 관리를 위한 연구들을 실시해왔다. 본 연구의 주 목적은 건조지역의 수자원 관리를 위해 건조지역 하천유역을 중심으로 지역빈도해석을 실시하여 신뢰할만한 확률수문량을 산정하는 것이다. 확률수문량 산정값의 정확도를 향상시키기 위해 지역빈도해석 모델에 쓰여 지는 새로운 지형학적 변수들을 제공하였고 수문학적 동질 지역을 구분 위해 수집된 각 하천유역의 형상들을 확인하여 동질 지역을 정의하였다. 예를 들면, 수지형 유역, 부채형 유역, 격자형 유역과 같은 다른 형상들을 구분하여 각 유역 형상 종류별로 동질 지역을 만들었다. 건조지역의 지역빈도해석을 위해 미국 건조지역의 105개 하천유역 유량자료들을 수집 및 이용하였다. 확률수문량 산정을 위하여 앙상블 인경신경망 (Ensemble Artificial Neural Network)과 정준 상관 계수(Canonical Correlation Analysis)를 이용한 지역빈도해석 모델을 만들었다. 제안된 모델의 수행평가와 정확성 평가를 위해 리샘플링 기법인 10-겹 교차 검증 (10-fold cross-validation), 잭나이프 (Jackknife) 기법들을 이용하였고 모델로부터 산정된 확률수문량값을 편향 (Bias), 상대 편향(rBias), 평균 제곱근 오차 (RMSE), 상대 평균 제곱근 오차 (rRMSE)를 통하여 산정 값과 실제 관측 값의 차이를 분석하였다. 그 결과 건조지역의 지역빈도해석을 위해 새롭게 제시된 지형학적 변수들을 사용하였을 때 모델의 수행능력이 향상되었음을 확인하였다. 또한 하천유역 형상에 따라 동질 지역을 구분하였을 때 향상된 확률수문량이 산정되었다. 향상된 지역빈도해석 모델을 통해 건조지역의 신뢰할만한 확률수문량을 산정함으로써 건조지역의 효과적인 수자원 관리를 위한 수공시설물 설계에 중요한 정보들을 제공할 것이다.