• 제목/요약/키워드: Homogeneity

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A Statistical Homogeneity Analysis of Seoul Rainfall using Bootstrap (Bootstrap 기법을 이용한 서울지점 강우자료의 통계적 동질성 분석)

  • Hwang, Seok-Hwan;Kim, Joong-Hoon;Yoo, Chul-Sang;Jung, Sung-Won;Yoo, Do-Guen
    • Journal of Korea Water Resources Association
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    • v.42 no.10
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    • pp.795-807
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    • 2009
  • In this study, homogeneity analysis was performed between rainfall observation data set of Chukwooki (CWK) and rainfall observation data set of modern rain gage (MRG) using Bootstrap method. Since traditional statistical homogeneity test method are validated only when distribution of their population is known, meteorological data which their statistical distributions of population are complicated were difficult to verify the homogeneity and there were plenty of room for doubt for their statistical significance using historical method. In this reason, in this study homogeneity test was evaluated between two data sets using bootstrap method which is not necessary to infer distribution of population. The test results show that there was an statistical homogeneity between CWK and MRG except for slight impact of climatical trend.

Evaluation Methods of Homogeneity for Feedstocks and Effect of Homogeneity on the Magnetic Properties of Plastic Magnets (플라스틱 자석 혼합물의 균질도 평가방법과 균질도가 자기특성에 미치는 영향)

  • 이석희;최준환;문탁진;정원용
    • Journal of the Korean Magnetics Society
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    • v.8 no.2
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    • pp.86-92
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    • 1998
  • Homegeneous feedstock is necessary to make plastic magents with uniform magnetic properties, therefore the optrimized mixing route and the homogeneity evaluation method are demanded. In this paper, method of homogeneity evaluation and effect of homogeneity on the magnetic prperites were investigated using Sr-ferrite /EVA plastic magnets. The feedstocks with different homogeneity were prepared using batch mixer and single screw extruder. The homogeneities of feedstocks were tested by torgue sensor, capilary rheometer, and measurement of magnetic properties. Mixing torque measurement using torque sensor was an effective method to determine the critical powder loading, but it was nor suitable to suitable to determine the feedstock mixing quality. Particle alignment measurement of a plastic magent was very accurate to evaluate the homogeneity, but expensive equipments were required to make and measure the samples. Pressure measurement using capillary rheometer was a very effective and easy method with high accuracy. Homogeneous feedstock increased the particle alignment of plastic magnet. Remanet flux density and maximum energy product increased linearly and quadratically with increasing particle alignment, respectively.

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A Simple Scoring Method to Calculate the Homogeneity and Coverage Indices of Dose Volume Histogram (DVH를 이용한 선량 균등률 및 덮임률 지수에 관한 연구)

  • Yoon Myong-Geun;Park Sung-Yong;Shin Dong-Ho;Park Jung-Hun;Lee Se-Byeong;Kim Dae-Yong;Kim Joo-Young;Cho Kwan-Ho
    • Progress in Medical Physics
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    • v.17 no.1
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    • pp.6-16
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    • 2006
  • The goal of this study was to develop new indices for effectively evaluating the dose coverage and homogeneity based on the target-volume dose-volume histogram (TV-DVH) of intensity-modulated radio-therapy treatment plans. A new coverage Index and a new homogeneity index were developed by integrating a modified TV-DVH and by fitting a TV-DVH with a modified step function, respectively. The coverage index, named the l-index, indicates whether the dose coverage for the target volume is adequate based on user-defined criteria. A lower l-index indicates higher dose coverage of the tumor volume. The index for assessing dose homogeneity in a target volume, named the n-index, is more accurate than the conventional method in evaluating the dose homogeneity in a tumor volume. The baseline treatment plan for a target volume coverage and homogeneity is discussed. The proposed simple indices have been demonstrated to be effective in evaluating the dose coverage and homogeneity for TV-DVHs.

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Design of a Magnet Assembly for an NMR Based Sensor Using Finite Element Analysis

  • Cho, S.I.;Chung, C.H.;Kim, S.C.
    • Agricultural and Biosystems Engineering
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    • v.1 no.1
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    • pp.49-53
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    • 2000
  • A magnet assembly is a critical element of a nuclear magnetic resonance(NMR) based sensor. Magnetic flux density and homogeneity are essential to its optimum performance. Geometry and magnet material properties determine the magnetic flux density and homogeneity of the assembly. This study was carried out to develop the design for a magnet assembly. A 2-D finite element model for the magnetic assembly was developed using ANSYS and evaluated the effects of adding shimming frames and steel bars in the corners of the rectangular steel cover which surrounded the magnet. The assembly was manufactured and evaluated. According to the ANSYS model, modified pole frames increased magnetic flux density by 8.3% and increased homogeneity by 83%. Addition of steel bars in the corners increased the magnetic flux density by 1%, and improved homogeneity up to three times. The difference between simulated and measured magnetic flux densities at the center point of the air gap was within 2.4%.

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Effect of Processing Conditions on the Homogeneity of Partially Degummed Silk Evaluated by FTIR Spectroscopy

  • Kim, Hyun Ju;Chung, Da Eun;Um, In Chul
    • International Journal of Industrial Entomology and Biomaterials
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    • v.26 no.1
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    • pp.54-60
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    • 2013
  • The partial degumming of silk has recently attracted researchers' attention because of its ability to produce silk textiles with new tactile properties, intermediate between the softness of fully degummed silk and the hardness of raw silk. However, it is difficult to obtain partially degummed silk in a homogenously degummed state due to the heterogeneous character of sericin removal. It is also difficult to examine the homogeneity of degumming. In the present study, Fourier transform infrared (FTIR) spectroscopy with attenuated total reflection (ATR) geometry was used to evaluate the effect of processing conditions on the degumming of silk yarns. The crystallinity index, calculated from FTIR spectra, showed an increase with the degumming ratio. Therefore, the homogeneity of degumming could be evaluated by the variation of crystallinity index for 30 different spots in silk yarns. The homogeneity of degumming was influenced by the total degumming time, the content of surfactant, and the liquor rate. No effect was observed upon changing the number of degumming cycles at the same total degumming time.

Homogeneity in Case/Control Numbers and North Indian Caste Criteria in Cervical Cancer/Female Urology Genetic-Studies at a Premier Medical Research Institute in Lucknow, India

  • Pandey, Saumya;Chandravati, Chandravati
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.10
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    • pp.6185-6187
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    • 2013
  • Cervical cancer has emerged as a major public health problem in Lucknow and New York in the $21^{st}$ century. Cancer genetic studies are essential to identify/stratify disease-susceptible individuals in a population-based cohort. Sample size homogeneity and North Indian caste in female urology genetic-studies are significant issues in meaningful interpretation of data. A review of scientific literature using Pubmed database was conducted, including an assessment of cervical cancer genetic studies conducted as part of the author's doctoral dissertation at a premier Lucknow-based medical research Institute. Sample size numbers and caste criteria in the North Indian cohort ($N{\leq}400$ subjects) were evaluated with homogeneity in the sample cohort data set(s). Subgroup caste-stratification of North Indian cohort is equally essential, for instance, Brahmin (e.g. Pandey), Vaishya (e.g. Mittal), Rajput (e.g. Singh) and Kshudra (e.g. Yadav) during the conception and design of genetics-based studies. Sample size homogeneity in histopathologically confirmed case and control numbers and caste-based stratification in a North Indian cohort is essential in single nucleotide polymorphism (SNP) studies in cervical cancer susceptible populations to draw more definitive conclusions.

Test of Homogeneity for Panel Bilinear Time Series Model (패널 중선형 시계열 모형의 동질성 검정)

  • Lee, ShinHyung;Kim, SunWoo;Lee, SungDuck
    • The Korean Journal of Applied Statistics
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    • v.26 no.3
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    • pp.521-529
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    • 2013
  • The acceptance of the test of the homogeneity for panel time series models allows for the pooling of the series to achieve parsimony. In this paper, we introduce a panel bilinear time series model as well as derive the stationary condition and the limiting distribution of the test statistic of the homogeneity test for the model. For the applications study, we use Korea Mumps data from January 2001 to December 2008. Finally, we perform test of homogeneity for the panel data with 8 independent bilinear time series.

Influence of impulsive line source and non-homogeneity on the propagation of SH-wave in an isotropic medium

  • Kakar, Rajneesh
    • Interaction and multiscale mechanics
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    • v.6 no.3
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    • pp.287-300
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    • 2013
  • In this paper, the effect of impulsive line on the propagation of shear waves in non-homogeneous elastic layer is investigated. The rigidity and density in the intermediate layer is assumed to vary quadratic as functions of depth. The dispersion equation is obtained by using the Fourier transform and Green's function technique. The study ends with the mathematical calculations for transmitted wave in the layer. These equations are in complete agreement with the classical results when the non-homogeneity parameters are neglected. Various curves are plotted to show the effects of non-homogeneities on shear waves in the intermediate layer.

Design of high homogeneity superconducting magnet (고균등자장 발생용 초전도 마그네트의 설계)

  • Jin, Hong-Beom;Nah, Wan-Soo;Ryo, Kang-Sik
    • Proceedings of the KIEE Conference
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    • 1994.07a
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    • pp.192-194
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    • 1994
  • High homogeneity and stability are required in superconducting magnet for Magnetic Resonance Imaging. In this paper, Magnetic Field theories for the design of high homogeneity magnet are introduced and multi-sections solenoid type coils are optimzed to produce highly homogeneous field.

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Testing Homogeneity of Diagonal Covariance Matrices of K Multivariate Normal Populations

  • Kim, Hea-Jung
    • Communications for Statistical Applications and Methods
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    • v.6 no.3
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    • pp.929-938
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    • 1999
  • We propose a criterion for testing homogeneity of diagonal covariance matrices of K multivariate normal populations. It is based on a factorization of usual likelihood ratio intended to propose and develop a criterion that makes use of properties of structures of the diagonal convariance matrices. The criterion then leads to a simple test as well as to an accurate asymptotic distribution of the test statistic via general result by Box (1949).

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