• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6B
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• pp.531-539
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• 2011

It has been widely acknowledged that climate system associated with extreme rainfall events was difficult to understand and extreme rainfall simulation in climate model was more difficult. This study developed a new model for extracting rainfall filed associated with extreme events as a way to characterize large scale climate system. Main interests are to derive location, size and direction of the rainfall field and this study developed an algorithm to extract the above characteristics from global climate data set. This study mainly utilized specific humidity and wind vectors driven by NCEP reanalysis data to define the rainfall field. Geometric first and second moments have been extensively employed in defining the rainfall field in selected zone, and an ellipsoid based model were finally introduced. The proposed geometric moments based ellipsoid model works equally well with regularly and irregularly distributed synthetic grid data. Finally, the proposed model was applied to space-time real rainfall filed. It was found that location, size and direction of the rainfall field was successfully extracted.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.106-116
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• 2011

USN(Ubiquitous Sensor Network) environment permits us to access whatever information we want, whenever we want. The technologies to provide a basement to these environments premise an accurate location establishment. Especially, ITS(Intelligent Transportation Systems) is easily constructed by applying USN technology. Localization can be categorized as either Range-based or Range-free. Range-based is known to be not suitable for the localization based on sensor network, because of the irregularity of radio propagation and the additional device requirement. The other side, Range-free is much appropriated for the resource constrained sensor network because it can actively locate by means of the communication radio. But, generally the location accuracy of Range-free is low. Especially, it is very low in a low-density environment. So, these two methods have both merits and demerits. Therefore, it requires a new method to be able to improve tracking accuracy by combining the two methods. This paper proposes the tracking scheme based on range-hybrid, which can markedly enhance tracking accuracy by effectively using the information of surrounding nodes and the RSSI(Received Signal Strength Indication) that does not require additional hardware. Additionally, we present a method, which can improve the accuracy of vehicle tracking by adopting the prediction mechanism. Simulation results show that our method outperforms other methods in the transportation simulation environment.

• Journal of Broadcast Engineering
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• v.19 no.6
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• pp.798-809
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• 2014

Video stabilization is performed to remove unexpected shaky and irregular motion from a video. It is often used as preprocessing for robust feature tracking and matching in video. Typical video stabilization algorithms are developed to compensate motion from surveillance video or outdoor recordings that are captured by a hand-help camera. However, since the vehicle video contains rapid change of motion and local features, typical video stabilization algorithms are hard to be applied as it is. In this paper, we propose a novel approach to compensate shaky and irregular motion in vehicle video using linear regression model and vertical projection histogram matching. Towards this goal, we perform vertical projection histogram matching at each sub region of an input frame, and then we generate linear regression model to extract vertical translation and rotation parameters with estimated regional vertical movement vector. Multiple binarization with sub-region analysis for generating the linear regression model is effective to typical recording environments where occur rapid change of motion and local features. We demonstrated the effectiveness of our approach on blackbox videos and showed that employing the linear regression model achieved robust estimation of motion parameters and generated stabilized video in full automatic manner.

• Journal of the Korea Computer Graphics Society
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• v.23 no.1
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• pp.33-38
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• 2017

In this paper, we suggest a method to simulate high-quality iguana animation by using low-quality motion capture data. Iguana motion data captured using a small number of markers cannot express its movement precisely, and even with a realistic skin mesh, it shows unnatural movement because of limited degrees of freedom. In order to solve this problem, we propose to simulate a natural and flexible movement by applying a soft-body simulation technique which models the movement of an iguana according to muscle forces and body's elastic forces. We construct a motion graph from the motion capture data to describe the iguana's various movements, and utilize it to select appropriate movements when the iguana moves. A target point on a terrain is set from the user's input, and a graph path is planned based on it. As a result, the input movement of iguana walking on a flat ground transforms to a movement that is adapted in an online manner to the irregular heights of the terrain. Such a movement is used to calculate the ideal muscle lengths that are needed for soft-body simulation. Lastly, a tetrahedral mesh of the iguana is physically simulated to adapt to various situations by applying a soft-body simulation technique.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.202-209
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• 1998

A three-dimensional numerical method based on the Green's integral equation is developed to predict the motion response and drift force in waves for the ocean monitoring facilities. In this method, we use source and doublet distribution, and triangular and rectangular eliments. To eliminate the irregular frequency phenomenon, the method of improved integral equation is applied and the time-mean drift force is calculated by the method of direct pressure integration over the body surface. To conform the validity of the present numerical method, some calculations for the floating sphere are performed and it is shown that the present method provides sufficiently reliable results. As a calculation example for the real facilities, the motion response and the drift force of the vertical cylinder type ocean monitoring buoy with 2.6 m diameter and 3,77 m draft are calculated and discussed. The obtained results of motion response can be used to determine the shape and dimension of the buoy to reduce the motion response, and other data such as the effect of motion reduction due to a damper can be predictable through these motion calculations. Also, the calculation results of drift force can be used in the design procedure of mooring system to predict the maximum wave load acting on the mooring system. The present method has, in principle, no restriction in the application to the arbitrary shape facilities. So, this method can be a robust tool for the design, installation, and operation of various kinds of the floating-type ocean monitoring facilities.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.3
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• pp.113-122
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• 2007

The rapid growth of aerial survey and remote sensing technology has enabled the rapid acquisition of very large amounts of geographic data, which should be analyzed using real-time visualization technology. The level of detail(LOD) algorithm is one of the most important elements for realizing real-time visualization. We chose the triangulated irregular network (TIN) method to generate normalized digital elevation model(DEM) data. First, we generated TIN data using contour lines obtained from a two-dimensional(2D) digital map and created a 2D grid array fitting the size of the area. Then, we generated normalized DEM data by calculating the intersection points between the TIN data and the points on the 2D grid array. We used constrained Delaunay triangulation(CDT) and ray-triangle intersection algorithms to calculate the intersection points between the TIN data and the points on the 2D grid array in each step. In addition, we simulated a three-dimensional(3D) terrain model based on normalized DEM data with real-time visualization using a Microsoft Visual C++ 6.0 program in the DirectX API library and a quad-tree LOD algorithm.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.458-467
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• 2019

The purpose of this study is the suggestion of optimized parameters in OI (Optimal Interpolation) by experimental study. The observation of applying optimal interpolation is ADCP (Acoustic Doppler Current Profiler) data at the southwestern sea of Korea. FVCOM (Finite Volume Coastal Ocean Model) is used for the barotropic model. OI is to the estimation of the gain matrix by a minimum value between the background error covariance and the observation error covariance using the least square method. The scaling factor and correlation radius are very important parameters for OI. It is used to calculate the weight between observation data and model data in the model domain. The optimized parameters from the experiments were found by the Taylor diagram. Constantly each observation point requires optimizing each parameter for the best assimilation. Also, a high accuracy of numerical model means background error covariance is low and then it can decrease all of the parameters in OI. In conclusion, it is expected to have prepared the foundation for research for the selection of ocean observation points and the construction of ocean prediction systems in the future.

• Survey Research
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• v.10 no.1
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• pp.113-139
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• 2009

It is desirable to use a monthly benchmarked construction indicator which contains the characteristics of statistical data in an annual survey in order to analyze the cyclical phenomenon of the construction activity. The benchmarked indicator is expected to improve the data quality in terms of accuracy, consistency, comparability, and completeness. In this paper, benchmarking methodologies of compiling monthly construction indicators arc researched by using a monthly prompt data holding short - term fluctuations and an annual survey data regarded as more accurate statistics than monthly data. The benchmarking is the methodology by which a high frequency data should he adjusted in order to hold the short-term and cyclical phenomena, and the long - term trend of two data groups with ensuring the consistency of an annual summation between a high frequency data and a low frequency data. This paper considered the numerical approach like pro rata distribution method, proportional Denton method, EFL or HP filter Benchmark - to - Indicator ratio method, and the model - based approach such as Chow and Lin method, $Fem{\acute{a}}ndez$ method. Also, the benchmarked construction indicators were estimated by early mentioned benchmarking methods with practical data, and these methods were empirically reviewed and compared. In case of construction indicators with severe seasonal fluctuations and irregulars, the numerical approach seemed to be performed more correctly than the model- based approach. Among numerical methods, the proportional Denton method used in general was a little nice. The HP filter Benchmark - to - Indicator ratio method may be considered with survey errors or measurement errors in an annual survey data.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.2
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• pp.81-92
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• 2011

High resolution seismic profiles (chirp and sparker system) were analyzed for the interpretation of nearshore sedimentary environments of Suyeong Bay, Busan. The sedimentary sequence is classified into three seismic units (SU1a, SU1b, and SU2), overlying acoustic basement, and each units can be defined as erosional and disconformable strata. The lowermost SU1a is characterized by the acoustically parallel and prolonged inner reflections, compared with the upper SU1b displays irregular internal reflectors. The uppermost unit, SU2, is acoustically transparent. The acoustic basement is incised with channels, probably due to the active erosion during the early period of transgression. The acoustic basement deepens eastward in the study area, suggesting primary association with the Suyeong River. The upper SU1a and SU1b units constitute lowland-fill strata. SU2 is widely distributed over the study area. High resolution seismic profiles of Suyeong Bay provide significant information crucial to the interpretation of sedimentary environmental history, which is closely related to the sea level change, estuarine environment and influx of terrestrial sediments from the adjacent rivers.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.2
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• pp.3-8
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• 2011

Recently, the demand for enterprise for service map providing and portal site services of a 3D virtual city model for public users has been expanding. Also, accuracy of the data, transfer rate and the update for the update for the lapse of time emerge are considered as more impertant factors, by providing 3D information with the web or mobile devices. With the latest technology, we have seen various 3D data through the web. With the VRML progressing actively, because it can provide a virtual display of the world and all aspects of interaction with web. It offers installation of simple plug-in without extra cost on the web. LiDAR system can obtain spatial data easily and accurately, as supprted by numerous researches and applications. However, in general, LiDAR data is obtained in the form of an irregular point cloud. So, in case of using data without converting, high processor is needed for presenting 2D forms from point data composed of 3D data and the data increase. This study expresses urban LiDAR data in 3D, 2D raster data that was applied by compressing algorithm that was used for solving the problems of large storage space and processing. For expressing 3D, algorithm that converts compressed LiDAR data into code Suited to VRML was made. Finally, urban area was expressed in 3D with expressing ground and feature separately.