• Title/Summary/Keyword: Spatial variance

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The Effects of Insoles for Postural Correction on Spatial-temporal Changes of Gait in Spastic Cerebral Palsy Children

  • Kim, Hee Tak;Lim, Sang Wan
    • Journal of International Academy of Physical Therapy Research
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    • v.6 no.2
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    • pp.840-845
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    • 2015
  • Improvement in functional gait is one of treatment goals in treatment of cerebral palsy children. This study intended to examine the effects of insoles for postural correction on gait in spastic cerebral palsy patients by investigating changes in gait temporal spatial parameters. As the subjects, 15 spastic bilateral cerebral palsy patients participated in this study. Temporal spatial parameters of gait were measured using GAITRite system under three gait conditions. Bare foot gait, gait in shoes, and gait in insoles for postural correction were conducted. In order to look at differences in temporal spatial parameters according to three gait conditions, repeated one way analysis of variance was conducted. As post hoc test, Bonferroni was conducted. A significant level was set at ${\alpha}=.05$. According to the result of this study, gait velocity, cadence, step length, stride length of the left lower extremity significantly changed. When the subjects put on customized insoles for postural correction, the effect was greatest. There were no significant changes in stance time, single support time, double support time, swing % of gait, and stance % of cycle. Therefore, gait with insoles for postural correction positively influenced functional gait improvement and will be able to be usefully employed for spastic cerebral palsy children as one of gait assistance devices.

The Study of Particle Filter Localization Algorithm Based on Magnetic Field Data

  • Chang, Kun;Huang, He;Jing, Changfeng;Deng, Nanshan
    • Journal of Korean Society for Geospatial Information Science
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    • v.24 no.2
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    • pp.107-112
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    • 2016
  • Most of the indoor positioning algorithms based on magnetic data mainly focus on reducing the accumulated error of the odometry data, such as signals produced by the inertial sensors. However, in most cases such as positioning by using smartphones in the indoor environment, those approaches seem unfeasible due to the absence of the inertial sensors. Thus, in this paper, we try to study a positioning algorithm exclusively based on the magnetic data. We refer to some thinking from the steps of Particle Filter and conduct an experiment to verify the application of the new algorithm. Besides, we use the variance of the result of the previous step to decrease the area to be matched in the next step, intending to improve the accuracy of the results. The result of the experiment shows that the new algorithm has a high probability to match with accuracy less than 2 meters in a 24 meters by 2.6 meters corridor.

Waveguide Spatial Interference Filtering in Adaptive Matched Field Processing (적응 정합장처리에서 도파관 공간간섭 필터링)

  • 김재수;김성일;신기철;김영규;박정수
    • The Journal of the Acoustical Society of Korea
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    • v.23 no.4
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    • pp.288-295
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    • 2004
  • Detection and localization of a slow and quiet target in shallow water environments is a challenging problem for which it is well known that snapshot is deficient because of a fast and strong interferer. This paper presents waveguide interference filtering technique that mitigate strong interferer problems in adaptive matched field processing. MCM (multiple constraint method) based on NDC (null direction constraint) has been proposed for new spatial interferer filter. MCM-NDC using replica force a interferer component to be filtered through CSDM (cross-spectral density matrix). This filtering have an effect on sidelobe reduction and restoring of signal gain of a quiet target. This technique was applied to a simulation on Pekeris waveguide and vertical array data from MAPLE03 (matched acoustic properties and localization experiment) in the East Sea and was shown to improve SBNR (signal-to-background-and-noise ratio) over the standard MVDR (minimum-variance distortionless response) and NSP (null space projection) technique.

Wavelet-based Fusion of Optical and Radar Image using Gradient and Variance (그레디언트 및 분산을 이용한 웨이블릿 기반의 광학 및 레이더 영상 융합)

  • Ye, Chul-Soo
    • Korean Journal of Remote Sensing
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    • v.26 no.5
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    • pp.581-591
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    • 2010
  • In this paper, we proposed a new wavelet-based image fusion algorithm, which has advantages in both frequency and spatial domains for signal analysis. The developed algorithm compares the ratio of SAR image signal to optical image signal and assigns the SAR image signal to the fused image if the ratio is larger than a predefined threshold value. If the ratio is smaller than the threshold value, the fused image signal is determined by a weighted sum of optical and SAR image signal. The fusion rules consider the ratio of SAR image signal to optical image signal, image gradient and local variance of each image signal. We evaluated the proposed algorithm using Ikonos and TerraSAR-X satellite images. The proposed method showed better performance than the conventional methods which take only relatively strong SAR image signals in the fused image, in terms of entropy, image clarity, spatial frequency and speckle index.

Study on Dimensionality Reduction for Sea-level Variations by Using Altimetry Data around the East Asia Coasts

  • Hwang, Do-Hyun;Bak, Suho;Jeong, Min-Ji;Kim, Na-Kyeong;Park, Mi-So;Kim, Bo-Ram;Yoon, Hong-Joo
    • Korean Journal of Remote Sensing
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    • v.37 no.1
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    • pp.85-95
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    • 2021
  • Recently, as data mining and artificial neural network techniques are developed, analyzing large amounts of data is proposed to reduce the dimension of the data. In general, empirical orthogonal function (EOF) used to reduce the dimension in the ocean data and recently, Self-organizing maps (SOM) algorithm have been investigated to apply to the ocean field. In this study, both algorithms used the monthly Sea level anomaly (SLA) data from 1993 to 2018 around the East Asia Coasts. There was dominated by the influence of the Kuroshio Extension and eddy kinetic energy. It was able to find the maximum amount of variance of EOF modes. SOM algorithm summarized the characteristic of spatial distributions and periods in EOF mode 1 and 2. It was useful to find the change of SLA variable through the movement of nodes. Node 1 and 5 appeared in the early 2000s and the early 2010s when the sea level was high. On the other hand, node 2 and 6 appeared in the late 1990s and the late 2000s, when the sea level was relatively low. Therefore, it is considered that the application of the SOM algorithm around the East Asia Coasts is well distinguished. In addition, SOM results processed by SLA data, it is able to apply the other climate data to explain more clearly SLA variation mechanisms.

A Comparative Study on Spatial Characteristics of Parcel by Type of Building Construction (건축행위 유형별 필지의 공간적 특성 비교연구)

  • Kim, Kijung;Kim, Dongjun;Lee, Seungil
    • Journal of Korea Planning Association
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    • v.54 no.6
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    • pp.27-42
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    • 2019
  • The purpose of this study is to identify the spatial characteristics of the parcels in which building construction occurred. In recent, urban development patterns in Korea have been shifting from the past. Small-scale development at parcel level is becoming more important in accordance with individual location needs in the low-growth era unlike public lead large-scale urban development in the rapid growth period. Therefore, it is necessary to study the spatial characteristics of the parcels where small-scale development takes place for future urban development management. This study used the chi square independence test, t-test and ANOVA (analysis of variance) to identify the spatial characteristics. The results of the study show that there is a spatial characteristics difference not only between building construction and non-building construction parcels, but also by type of building construction. The parcel where the building construction occurred have a higher proportion in detached house, major commercial districts, district unit planning areas, and commercial areas. In addition, it is caused by parcels, which are large scale and economically valuable, and are influenced by traffic factors such as urban centers and subway accessibility. As a result of each type of building construction, the parcels where the building use change occurred have spatial characteristic difference compared to other building construction, while the spatial characteristics are similar between the new construction/extension and new construction/extension with change of use. Based on this results, it will be possible to identify areas with high demand for small-scale development in the future and to utilize them for planning management of urban development. Furthermore, it will be possible to manage development demand by type of building construction, and to prepare differentiated plans considering the appropriateness of development plan, availability of infrastructure, and harmony with surrounding environment.

An Improved Remote Sensing Image Fusion Algorithm Based on IHS Transformation

  • Deng, Chao;Wang, Zhi-heng;Li, Xing-wang;Li, Hui-na;Cavalcante, Charles Casimiro
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.3
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    • pp.1633-1649
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    • 2017
  • In remote sensing image processing, the traditional fusion algorithm is based on the Intensity-Hue-Saturation (IHS) transformation. This method does not take into account the texture or spectrum information, spatial resolution and statistical information of the photos adequately, which leads to spectrum distortion of the image. Although traditional solutions in such application combine manifold methods, the fusion procedure is rather complicated and not suitable for practical operation. In this paper, an improved IHS transformation fusion algorithm based on the local variance weighting scheme is proposed for remote sensing images. In our proposal, firstly, the local variance of the SPOT (which comes from French "Systeme Probatoire d'Observation dela Tarre" and means "earth observing system") image is calculated by using different sliding windows. The optimal window size is then selected with the images being normalized with the optimal window local variance. Secondly, the power exponent is chosen as the mapping function, and the local variance is used to obtain the weight of the I component and match SPOT images. Then we obtain the I' component with the weight, the I component and the matched SPOT images. Finally, the final fusion image is obtained by the inverse Intensity-Hue-Saturation transformation of the I', H and S components. The proposed algorithm has been tested and compared with some other image fusion methods well known in the literature. Simulation result indicates that the proposed algorithm could obtain a superior fused image based on quantitative fusion evaluation indices.

Temporal and Spatial Variations of SST and Ocean Fronts in the Korean Seas by Empirical Orthogonal Function Analysis

  • Yoon, Hong-Joo;Byun, Hye-Kyung;Park , Kwang-Soon
    • Korean Journal of Remote Sensing
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    • v.21 no.3
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    • pp.213-219
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    • 2005
  • In the Korean seas, Sea Surface Temperature (SST) and Thermal ronts (TF) were analyzed temporally and spatially during 8 years from 1993 to 2000 using NOAA/AVHRR MCSST. In the application of EOF analysis for SST, the variance of the 1st mode was 97.6%. Temporal components showed annual variations, and spatial components showed that where it is closer to continents, the SST variations are higher. Temporal components of the 2nd mode presented higher values of 1993, 94 and 95 than those of other years. Although these phenomena were not remarkable, they could be considered ELNI . NO effects to the Korean seas as the time was when ELNI . NO occurred. The Sobel Edge Detection Method (SEDM) delineated four fronts: the Subpolar Front (SPF) separating the northern and southern parts of the East Sea; the Kuroshio Front (KF) in the East China Sea, the South Sea Coastal Front (SSCF) in the South Sea, and the Tidal Front (TDF) in the West Sea. TF generally occurred over steep bathymetry slopes, and spatial components of the 1st mode in SST were bounded within these frontal areas. EOF analysis of SST gradient values revealed the temporal and spatial variations of the TF. The SPF and SSCF were most intense in March and October; the KF was most significant in March and May.

A Study on Improved Denoising Algorithm for Edge Preservation in AWGN Environments (AWGN환경에서 에지보호를 위한 개선된 잡음제거 알고리즘에 관한 연구)

  • Yinyu, Gao;Kim, Nam-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.8
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    • pp.1773-1778
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    • 2012
  • Nowadays, the high quality of image is required with the demand for digital image processing devices is rapidly increasing. But image always damaged by many kinds of noises and it is necessary to remove noise and the denoising becomes one of the most important fields. In many cases image is corrupted by AWGN(additive white Gaussian noise). In this paper, we proposed an improved denoising algorithm with edge preservation. The proposed algorithm averages values processed by spatial weighted filter and self adaptive weighted filter. Then we add the value which is computed by the equation considering variance of mask and the estimated noise variance. Through the experience, the proposed filter performs well on noise suppression and edge preservation properties and improves the image visual quality.

Multi-Frame Super-Resolution of High Frequency with Spatially Weighted Bilateral Total Variance Regularization

  • Lee, Oh-Young;Park, Sae-Jin;Kim, Jae-Woo;Kim, Jong-Ok
    • IEIE Transactions on Smart Processing and Computing
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    • v.3 no.5
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    • pp.271-274
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    • 2014
  • Bayesian based Multi-Frame Super-Resolution (MF-SR) has been used as a popular and effective SR model. On the other hand, the texture region is not reconstructed sufficiently because it works on the spatial domain. In this study, the MF-SR method was extended to operate on the frequency domain to improve HF information as much as possible. For this, a spatially weighted bilateral total variation model was proposed as a regularization term for a Bayesian estimation. The experimental results showed that the proposed method can recover the texture region more realistically with reduced noise, compared to conventional methods.