• Title/Summary/Keyword: multivariate statistic

Search Result 94, Processing Time 0.023 seconds

Application of Multispectral Remotely Sensed Imagery for the Characterization of Complex Coastal Wetland Ecosystems of southern India: A Special Emphasis on Comparing Soft and Hard Classification Methods

  • Shanmugam, Palanisamy;Ahn, Yu-Hwan;Sanjeevi , Shanmugam
    • Korean Journal of Remote Sensing
    • /
    • v.21 no.3
    • /
    • pp.189-211
    • /
    • 2005
  • This paper makes an effort to compare the recently evolved soft classification method based on Linear Spectral Mixture Modeling (LSMM) with the traditional hard classification methods based on Iterative Self-Organizing Data Analysis (ISODATA) and Maximum Likelihood Classification (MLC) algorithms in order to achieve appropriate results for mapping, monitoring and preserving valuable coastal wetland ecosystems of southern India using Indian Remote Sensing Satellite (IRS) 1C/1D LISS-III and Landsat-5 Thematic Mapper image data. ISODATA and MLC methods were attempted on these satellite image data to produce maps of 5, 10, 15 and 20 wetland classes for each of three contrast coastal wetland sites, Pitchavaram, Vedaranniyam and Rameswaram. The accuracy of the derived classes was assessed with the simplest descriptive statistic technique called overall accuracy and a discrete multivariate technique called KAPPA accuracy. ISODATA classification resulted in maps with poor accuracy compared to MLC classification that produced maps with improved accuracy. However, there was a systematic decrease in overall accuracy and KAPPA accuracy, when more number of classes was derived from IRS-1C/1D and Landsat-5 TM imagery by ISODATA and MLC. There were two principal factors for the decreased classification accuracy, namely spectral overlapping/confusion and inadequate spatial resolution of the sensors. Compared to the former, the limited instantaneous field of view (IFOV) of these sensors caused occurrence of number of mixture pixels (mixels) in the image and its effect on the classification process was a major problem to deriving accurate wetland cover types, in spite of the increasing spatial resolution of new generation Earth Observation Sensors (EOS). In order to improve the classification accuracy, a soft classification method based on Linear Spectral Mixture Modeling (LSMM) was described to calculate the spectral mixture and classify IRS-1C/1D LISS-III and Landsat-5 TM Imagery. This method considered number of reflectance end-members that form the scene spectra, followed by the determination of their nature and finally the decomposition of the spectra into their endmembers. To evaluate the LSMM areal estimates, resulted fractional end-members were compared with normalized difference vegetation index (NDVI), ground truth data, as well as those estimates derived from the traditional hard classifier (MLC). The findings revealed that NDVI values and vegetation fractions were positively correlated ($r^2$= 0.96, 0.95 and 0.92 for Rameswaram, Vedaranniyam and Pitchavaram respectively) and NDVI and soil fraction values were negatively correlated ($r^2$ =0.53, 0.39 and 0.13), indicating the reliability of the sub-pixel classification. Comparing with ground truth data, the precision of LSMM for deriving moisture fraction was 92% and 96% for soil fraction. The LSMM in general would seem well suited to locating small wetland habitats which occurred as sub-pixel inclusions, and to representing continuous gradations between different habitat types.

The Factors Influencing the Asthenopia of Emmetropia with Phoria (사위를 가진 정시안의 안정피로에 영향을 미치는 요인)

  • Kim, Jung-Hee;Lee, Dong-Hee
    • Journal of Korean Ophthalmic Optics Society
    • /
    • v.10 no.1
    • /
    • pp.71-82
    • /
    • 2005
  • The aim of this study was to provide fundamental data for the factors influencing the asthenopia of emmetropia with phoria and alleviation of asthenopia. A total of 348 subjects, aged between 19 and 30 years old, who had no strabismus, an eye trouble or whole body disease, were examined using corrected visual acuity, corrected diopter, stereopsis and suppression tests from September of 2002 to September of 2004. We excluded 21 subjects for the following reasons: if they had an amblyopia affecting binocular vision or inaccurate data. After these exclusions, 327 subjects remained. We then individually measured the refractive error correction, pupillary distance, optical center distance, phoria, convergence, accommodation and the AC/A as well as the asthenopia during binocular vision using a questionnaire. After analysis of factors affecting asthenopia, we also examined the reductive effect of a prism on the asthenopia in subjects who had asthenopia. To determine the factors affecting asthenopia during binocular vision, statistic analyses were carried out using the Chi-square test and the multivariate Logistic regression model. The results of this study were as follow. For asthenopia during near binocular vision of emmetropia with phoria, in case of the lower the accommodation and convergence, a significantly higher rate of asthenopia was observed (p<0.001). When the AC/A is lower, the higher the rate of asthenopia was observed but not significantly and there was no association between phoria and asthenopia. When the multivariate logistic regression model was used to determine factors affecting binocular vision of emmetropia with phoria, in case of the lower accommodation and convergence, a significantly higher rate of asthenopia was observed. when the phoria is esophoria or higher exophoria, or when the AC/A is lower than normal, the higher the rate of asthenopia was observed but not significantly and there was no association between phoria. AC/A and asthenopia. Therefore accommodation and convergence could be predictive factors for asthenopia during near distance binocular vision. Prism was used among' subjects who had asthenopia during near distance binocular vision, the symptom of asthenopia was eased up to 74.2% in emmetropia with phoria.

  • PDF

Relationship between S-Phase Fraction and Survival Time in Patients with Primary Squamous Lung Cancer (편평상피성 폐암에 있어서 S-Phase Fraction과 생존기간과의 관계)

  • Jung, Byung-Hak;Kang, Jeong-Seong;Chang, Keun;Jeong, Eun-Taik;Chung, Hun-Taeg;Moon, Hyung-Bae
    • Tuberculosis and Respiratory Diseases
    • /
    • v.40 no.6
    • /
    • pp.669-676
    • /
    • 1993
  • Background: DNA content analysis of human solid tumor is now widely performed by flow cytometric study. One of the most interesting and potentially important observation in this field is that proliferative activity(S-Phase fraction of cell cycle) may profoundly affect prognosis. Method: S-Phase fraction(SPF) have been measured by flow cytometric method using tumor cells isolated from paraffin embedded tissue. To evaluate the prognostic significance, SPF of squamous lung cancer cell was assessed in 21 patients who died without any specific treatment. Results: 1) Mean survival time of squamous lung cancer patients was 225(${\pm}162$) days. Survival time were shortened, when TNM stage and PS scale were advanced. 2) Mean value of SPF of squamous lung cancer patients was 23.4(${\pm}11.3$)%. SPF had nothing to do with advance of TNM stage and PS scale. 3) Mean survival time of high SPF group(more than 20% of cell proliferation cycle) and low SPF group were 153(${\pm}99$) days and 342(${\pm}180$) days(p<0.01). In each identical TNM stage and PS scale, there were also statistic significant differences in mean survival time between high and low SPF group. Conclusion: On multivariate analysis including TNM stage and performance status, SPF was the significant and independent prognostic factor in the primary squamous lung cancer patients group.

  • PDF

The structural relationships between organizational ethical, job satisfaction and organizational citizenship behavior of private security guards (민간경비원의 조직윤리, 직무만족 및 조직시민행동의 구조적 관계)

  • Kim, Young-Hyun;Park, Kill-Jun
    • Korean Security Journal
    • /
    • no.42
    • /
    • pp.59-85
    • /
    • 2015
  • The purpose of this study is to establish the structural relationship among organizational ethical climate, job satisfaction, and organizational citizenship behavior. It was intended for the private security guards who work in the security companies in Seoul and Gyeonggi from Jan. 1st, 2014 to Apr. 1st, 2014 to achieve the purpose like this. Purposive sampling was used as the sampling method according to this and sampling of 400 persons was done. However, the samples of 372 persons were finally used in the analysis through the process to check faithless answers, double answers, and abnormal data. The collected data was analyzed according to the purpose of the study by utilizing STATA 13.0 and AMOS 17.0. And for statistic techniques, frequency analysis, descriptive analysis, multivariate normality, confirmatory factor analysis(CFA), Pearson's correlation analysis, and structural equation model analysis were carried out. The conclusion gotten from this study through the data analyses according to the methods and procedure like this is as follow: First, organizational ethical climate has found to have the positive effect on job satisfaction(Non-standard $B=1.427^{***}$). That is, it can be interpreted that organizational ethical climate positively affects superiors, fellow employees, pay, current duties, and chances of promotion. Second, job satisfaction has found not to have the significant effect on organizational citizenship behavior. That is, it can be interpreted that job satisfaction does not affect altruism, conscience, and participation behavior. Third, organizational ethical climate has found to have the positive effect on organizational citizenship behavior (Non-standard $B=.361^{***}$). That is, it can be interpreted that organizational ethical climate positively affects altruism, conscience, and participation behavior. Fourth, the relationship between organizational ethical climate and organizational citizens has found that there is no any indirect effect in the bootstrapping estimation result to establish the indirect effect of job satisfaction. Fifth, the relationship between organizational ethical climate and job satisfaction has found that there are the moderating effects in the analytical result of the moderating effects of person-organization fit. That is, the effects of organizational ethical climate on job satisfaction have found that the groups with higher person-organization fit are more positive than those with lower person-organization fit. Sixth, the relationship between job satisfaction and organizational citizenship behavior has found that there are moderating effects in the analytical result of person-organization fit. That is, the effects of job satisfaction on organizational citizenship behavior have found that the groups with higher person-organization fit are more positive than those with lower person-organization fit.

  • PDF