• Journal of Information Processing Systems
• /
• v.16 no.3
• /
• pp.688-698
• /
• 2020

Point clouds have ability to express the spatial entities, however, the point clouds redundancy always involves some uncertainties in computer recognition and model construction. Therefore, point clouds thinning is an indispensable step in point clouds model reconstruction and other applications. To overcome the shortcomings of complex classification index and long time consuming in existing point clouds thinning algorithms, this paper proposes a point clouds fast thinning algorithm. Specifically, the two-dimensional index is established in plane linear array (x, y) for the scanned point clouds, and the thresholds of adjacent point distance difference and height difference are employed to further delete or retain the selected sample point. Sequentially, the index of sample point is traversed forwardly and backwardly until the process of point clouds thinning is completed. The results suggest that the proposed new algorithm can be applied to different targets when the thresholds are built in advance. Besides, the new method also performs superiority in time consuming, modelling accuracy and feature retention by comparing with octree thinning algorithm.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.24 no.2
• /
• pp.40-51
• /
• 2021

The purpose of this study is to diagnose urban spatial structures using spatial modeling techniques for balanced urban development as part of sustainable urban growth management. Since urban spatial structure is an interaction of various activities, it is necessary to interpret the analysis results in conjunction with the analysis of changes in spatial structural elements. In this study, population and transportation were approached for research purposes. Population data were applied to the Getis-Ord G_i^* method, a spatial statistical technique, to analyze the concentration-decreasing region of the population. Traffic data analyzed the trend of centrality change by applying commuting traffic O-D data to Social Network Analysis techniques. The analysis showed that urban imbalance was growing, and the centrality of transportation was changing. The results of the analysis of spatial structure elements could be interpreted by linking the results of each factor to each neighborhood unit, predicting changes in urban spatial structure and suggesting directions for sustainable urban growth management.These results could also be used as a decision-making tool for various urban growth management policies introduced to cope with rapid urban development and uncontrollable development in many cities around the world.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.571-574
• /
• 2005

In this paper, we propose an efficient image segmentation technique for large-sized monochrome images using a hybrid approach which combines threshold and region-based techniques. First, an image is partitioned into fixed-size blocks and for each block the representative intensity is determined by averaging pixel intensities within the block. Next, the neighborhood blocks that have similar characteristics with respect to a specific threshold are merged in order to form candidate regions. Finally, those candidate regions are refined to get final target object regions by merging regions considering the spatial locality and certain criteria. We have performed experiments on images selected from various domains and showed that our technique was able to extract target object regions appropriately from most images.

• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.2113-2115
• /
• 2006

This paper proposes a spatio-temporal correlation algorithm that takes advantage of the spatial and temporal correlations in video streams for error concealment. The spatio-temporal correlation algorithm sets the neighborhood area of the damaged part as a reference window, then finds the area that best matches the reference window in the previous frame. The best-matched area in the previous frame replaces the damaged part in the current frame. The results of ten variations of the proposed algorithm are compared with conventional error concealment methods. These methods include the ones applicable to P-frames as well as I-frames. The comparison results show that the proposed algorithm is very efficient for l-frame error concealment with a large motion between frames.

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.12-14
• /
• 2005

In this paper, we proposed an temporal error concealment (EC) using the proposed boundary matching method and the adaptive block matching method. The proposed boundary matching method improves the spatial correlation of the macroblocks (MBs) by reusing the pixels of the concealed MB to estimate a motion vector of a error MB. The adaptive block matching method inspects the horizontal edge and the vertical edge feature of a error MB surroundings, and it conceals the error MBs in reference to more stronger edge feature. This improves video quality by raising edge connection feature of the error MBs and the neighborhood MBs. In particular, we restore a lost MB as the unit of 8${\times}$16 block or 16${\times}$8 block by using edge feature from the surrounding macroblocks. Experimental results show that the proposed algorithm gives better results than the conventional algorithms from a subjective and an objective viewpoint.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.1
• /
• pp.1-7
• /
• 2006

Linear stability analysis of 2-dimensional wall jet is conducted by using parabolized stability equation (PSE). Wall jet is found to be modelled well by boundary layer approximation except for the neighborhood of the nozzle exit, and the introduction of local similarity variable makes the streamwise basic flow Reynolds number independent. Stability characteristics of the wall jet obtained

• Journal of the Korean Institute of Landscape Architecture
• /
• v.23 no.3
• /
• pp.155-166
• /
• 1995

The aim of this paper was to investigate images of neighborhood parks and pergola facilities. 280 individuals responded to the 19 semantic differential pollar terms for all four parks. A 7-point semantic differential scale was used. Results from the data analysis suggest several important findings; 1. Mean scores were significantly different in most of S.D.scales according to park and pergola facilities types. As compared with park, S.D.scales values of pergola varied with its visual identity in the spatial composition of park. 2. Data from the factor analysis revealed that four dimensions appeared for all park and pergola types : "Evaluation ", "Potentiality", "Variety", and "Familiarity". 3. In terms of the "Familiarity" dimension, Omok park and its pergola were viewed a ssignificantly more familiar than any of the other three areas. 4. Parks were perceived more positive than pergolas images in the dimensions of "Evaluation ", "Variety", and "Familiarity". 5. Regression analysis showed that "Evaluation "and "Variety" dimensions were mainly related to visual preference.

• ETRI Journal
• /
• v.44 no.4
• /
• pp.624-640
• /
• 2022

Taxi-demand forecasting and hotspot prediction can be critical in reducing response times and designing a cost effective online taxi-booking model. Taxi demand in a region can be predicted by considering the past demand accumulated in that region over a span of time. However, other covariates-like neighborhood influence, sociodemographic parameters, and point-of-interest data-may also influence the spatiotemporal variation of demand. To study the effects of these covariates, in this paper, we propose three models that consider different covariates in order to select a set of independent variables. These models predict taxi demand in spatial units for a given temporal resolution using linear and ensemble regression. We eventually combine the characteristics (covariates) of each of these models to propose a robust forecasting framework which we call the combined covariates model (CCM). Experimental results show that the CCM performs better than the other models proposed in this paper.

• Journal of Korean Living Environment System
• /
• v.21 no.6
• /
• pp.976-986
• /
• 2014

Health is an important topic of 21st century and its meaning has been changed in the direction of more inclusive and diverse way. The meaning of health became 'Community Property' to find in the social relations, and true health is considered to be made when forming 'sense of self' through their role in social relations. The community is the basic mechanism that builds social relationship, therefore it is an essential element to realize the health of modern society. In the modern concept of community, imaginal link is considered more important than physical spatial boundaries, and there is a tendency to depend more on the inter-relationship within it. This is based on the concept of health and community that formed in the changed paradigm, this study covers the concept of health community through a new approach.

• Journal of Astronomy and Space Sciences
• /
• v.31 no.1
• /
• pp.7-13
• /
• 2014

Variabilities in the solar wind cause disturbances throughout the heliosphere on all temporal and spatial scales, which leads to changeable space weather. As a view of space weather forecasting, in particular, it is important to know direct and indirect causes modulating the space environment near the Earth in advance. Recently, there are discussions on a role of the interaction of the solar wind with Mercury in affecting the solar wind velocity in the Earth's neighborhood during its inferior conjunctions. In this study we investigate a question of whether other parameters describing the space environment near the Earth are modulated by the inner planets' wake, by examining whether the interplanetary magnetic field and the proton density in the solar wind observed by the Advanced Composition Explorer (ACE) spacecraft, and the geomagnetic field via the Dst index and Auroral Electrojet index (AE index) are dependent upon the relative position of the inner planets. We find there are indeed apparent variations. For example, the mean variations of the geomagnetic fields measured in the Earth's neighborhood apparently have varied with a timescale of about 10 to 25 days. Those variations in the parameters we have studied, however, turn out to be a part of random fluctuations and have nothing to do with the relative position of inner planets. Moreover, it is found that variations of the proton density in the solar wind, the Dst index, and the AE index are distributed with the Gaussian distribution. Finally, we point out that some of properties in the behavior of the random fluctuation are to be studied.