• Title/Summary/Keyword: sample points

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A SURFACE RECONSTRUCTION METHOD FOR SCATTERED POINTS ON PARALLEL CROSS SECTIONS

  • Kim, Phil-Su
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.9 no.2
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    • pp.29-43
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    • 2005
  • We consider a surface reconstruction problem from geometrical points (i.e., points given without any order) distributed on a series of smooth parallel cross sections in ${\mathbb{R}}^3$. To solve the problem, we utilize the natural points ordering method in ${\mathbb{R}}^2$, described in [18], which is a method of reconstructing a curve from a set of sample points and is based on the concept of diffusion motions of a small object from one point to the other point. With only the information of the positions of these geometrical points, we construct an acceptable surface consisting of triangular facets using a heuristic algorithm to link a pair of parallel cross-sections constructed via the natural points ordering method. We show numerical simulations for the proposed algorithm with some sets of sample points.

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Estimating using the method of adaptive searching observation (적합탐색 관찰방법을 이용한 추정)

  • 변종석;남궁평
    • The Korean Journal of Applied Statistics
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    • v.9 no.2
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    • pp.145-159
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    • 1996
  • We propose an adaptive searching method using some spatial relations among sample points to estimate the interesting area in the spatial population. The fundamental idea is to observe the neighboring sample points when a sample point is satified with some condition of an adaptive searching observation. For obseving the sample points with this method to estimate the area the sample size is decreased. From this result, we may expect to reduce the cost and time consuming in observation the sample points and to draw the shape of the interesting area without prior information of an spatial population. Some analytical simulation results are also presented.

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A Hybrid Algorithm for Online Location Update using Feature Point Detection for Portable Devices

  • Kim, Jibum;Kim, Inbin;Kwon, Namgu;Park, Heemin;Chae, Jinseok
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.9 no.2
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    • pp.600-619
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    • 2015
  • We propose a cost-efficient hybrid algorithm for online location updates that efficiently combines feature point detection with the online trajectory-based sampling algorithm. Our algorithm is designed to minimize the average trajectory error with the minimal number of sample points. The algorithm is composed of 3 steps. First, we choose corner points from the map as sample points because they will most likely cause fewer trajectory errors. By employing the online trajectory sampling algorithm as the second step, our algorithm detects several missing and important sample points to prevent unwanted trajectory errors. The final step improves cost efficiency by eliminating redundant sample points on straight paths. We evaluate the proposed algorithm with real GPS trajectory data for various bus routes and compare our algorithm with the existing one. Simulation results show that our algorithm decreases the average trajectory error 28% compared to the existing one. In terms of cost efficiency, simulation results show that our algorithm is 29% more cost efficient than the existing one with real GPS trajectory data.

Reconstructing Curves With Self-intersections (자기교차를 가지는 곡선 재구성)

  • Kim, Hyoung-Seok B.
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.9
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    • pp.2016-2022
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    • 2010
  • We propose a new algorithm for reconstructing curves with self-intersections from sample points. In general, the result of curve reconstruction depends on how to select and order the representative points to resemble the shape of sample points. Most of the previous point ordering approaches utilize the Euclidean distance to compute the proximity of sample points without directional information, so they can not solve the non-simple curve reconstruction problem. In this paper, we develop a new distance estimating the adjacency between sample points, which is derived from the standard normal distribution of Brownian motion. Experimental results show that this approach is very effective to non-simple curve reconstruction.

An Economic Design of the EWMA Control Charts with Variable Sampling Interval (VSI EWIMA 관리도의 경제적 설계)

  • 송서일;정혜진
    • Journal of Korean Society for Quality Management
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    • v.30 no.4
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    • pp.1-14
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    • 2002
  • Traditional SPC techniques are looking out variation of process by fixed sampling interval and fixed sample size about every hour, the process of in-control or out-of-control couldn't be detected actually when the sample points are plotted near control limits, and it takes no notice of expense concerned with such sample points. In this paper, to overcome that, consider VSI(variable sampling interval) EWMA control charts which VSI method is applied. The VSI control charts use a short sampling internal if previous sample points are plotted near control limits, then the process has high probability of out-of-control. But it uses a long sampling interval if they are plotted near centerline of the control chart, since process has high possibility of in-control. And then a comparison and analysis between FSI(fixed sampling interval) and VSI EWMA in the statistical aspect and economic aspect is studied. Finally, we show that VSI EWMA control chart is more efficient than FSI EWMA control chart in the both aspects.

A Note on Parametric Bootstrap Model Selection

  • Lee, Kee-Won;Songyong Sim
    • Journal of the Korean Statistical Society
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    • v.27 no.4
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    • pp.397-405
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    • 1998
  • We develop parametric bootstrap model selection criteria in an example to fit a random sample to either a general normal distribution or a normal distribution with prespecified mean. We apply the bootstrap methods in two ways; one considers the direct substitution of estimated parameter for the unknown parameter, and the other focuses on the bias correction. These bootstrap model selection criteria are compared with AIC. We illustrate that all the selection rules reduce to the one sample t-test, where the cutoff points converge to some certain points as the sample size increases.

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Effects of Silver Spike Point Therapy on Blood Flow of the Middle Cerebral Arteries in Headache Patients When Applied to Acupuncture Points (경혈에 적용한 은침점 자극치료가 두통환자의 중대뇌동맥 혈류속도 및 통증에 미치는 영향)

  • Seo, Hyo-Seok;Yun, Young-Dae
    • Korean Journal of Acupuncture
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    • v.25 no.3
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    • pp.29-41
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    • 2008
  • Objectives : The aim of this study is to examine the effects of SSP(silver-spike point) therapy, applied to acupuncture points, on the middle cerebral arteries blood flows of sample group(tention-type headache patients, n=12) and control group(non tension-type headache patients, n=12), and on the reduction of their headaches, when applied to acupuncture points. Methods : We stimulated 6 acupuncture points for headache with the SSP(three times a week for three weeks), and measured VAS(visual analogue scale) and the blood flow of the middle cerebral arteries with TCD(transcranial doppler ultrasonography). Results : The blood flow of the middle cerebral artery and VAS of the sample group and the control group were compared four times(initial, 1weeks, 2weeks, 3weeks) and significant differences in the measurements were found at 3 weeks(p<.05). The blood flow of the middle cerebral artery of the sample group was significantly increased, and VAS was significantly decreased in both groups. Conclusions : The silver-spike-point low-frequency electrical-stimulation treatment, applied to acupuncture points, can significantly increase the blood flow of the middle cerebral arteries in headache patients and can thus alleviate their headaches.

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An Adaptive Unfolding Method for Visualizing Wrinkled Colon Surface (대장의 굴곡면을 가시화하기 위한 적응형 펼친 영상 기법)

  • Lee Jin-Hee;Shin Byeong-Seok
    • Journal of Korea Multimedia Society
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    • v.9 no.9
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    • pp.1160-1172
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    • 2006
  • Unfolding is an efficient technique to detect colorectal disease since it represents entire shape of colon at a glance. However, the previous unfolding methods may miss the surface located behind the folds or high curvature areas. To solve the problem, we propose an adaptive unfolding method that controls the number of rays in accordance with the surface complexity. In the first step, we find sample points of longer and shorter distance between the sample points and the colon surface, and then determine them as based control points. Next, for reaching rays of sample points in the wrinkled colon surface, sample points are shifted toward the control points that have the long distance. Lastly, we perform a 2D scaling which solves local distortions of the unfolding surface and avoids missing surface. Consequently, our method could be visualized the hidden surface of colon organ in detail.

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An Object-based Stereo Matching Method Using Block-based Segmentation (블록 기반 영역 분할을 이용한 객체 기반 스테레오 정합 기법)

  • Kwak No-Yoon
    • Journal of Digital Contents Society
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    • v.5 no.4
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    • pp.257-263
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    • 2004
  • This paper is related to the object-based stereo matching algorithm which makes it possible to estimate inner-region disparities for each segmented region. First, several sample points are selected for effectively representing the segmented region, Next, stereo matching is applied to the small area within segmented region which existed in the neighborhood or each sample point. Finally, inner-region disparities are interpolated using a plane equation with disparity of each selected sample. According to the proposed method, the problem of feature-based method that the depth estimation is possible only in the feature points can be solved through the propagation of the disparity in the sample point into the inside of the region. Also, as selecting sample points in contour of segmented region we can effectively suppress obscurity which is occurred in the depth estimation of the monotone region in area-based methods.

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Comparisons of Various DEM Interpolation Techniques

  • Kim, Tae-Jung
    • Proceedings of the KSRS Conference
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    • 1998.09a
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    • pp.163-168
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    • 1998
  • Extracting a Digital Elevation Model (DEM) from spaceborne imagery is important for cartographic applications of remote sensing data. The procedure for such DEM generation can be divided into stereo matching, sensor modelling and DEM interpolation. Among these, DEM interpolation contributes significantly to the completeness and accuracy of a DEM and, yet, this technique is often considered "trivial". However, na\ulcornere DEM interpolation may result in a less accurate and sometimes meaningless DEM. This paper reports the performance analysis of various DEM interpolation techniques. Using a manually derived DEM as reference, a number of sample points were created randomly. Different interpolation techniques were applied to the sample points to generate DEMs. The performance of interpolation was assessed by the accuracy of such DEMs. The results showed that kriging gave the best results at all times whereas nearest neighborhood interpolation provided a fast solution with moderate accuracy when sample points were large enough.

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