• Korean Journal of Remote Sensing
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• v.18 no.5
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• pp.255-261
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• 2002

Strong and coherent radar backscattering signals are observed over oyster sea farms that consist of artificial structures installed on the bottom. We successfully obtained 21 coherent interferograms from 11 JERS-1 SAR data sets even though orbital baselines (up to 2 km) or temporal baselines (up to 1 year) were relatively large. The coherent phases preserved in the sea farms are probably formed by double bouncing from sea surface and the sea farming structures, and consequently they are correlated with tide height (or instantaneous sea level). Phase unwrapping is required to restore the absolute sea level. We show that radar backscattering intensity is roughly correlated with the sea surface height, and utilize the fact to determine the wrapping counts. While the SAR image intensity gives a rough range of absolute sea level, the interferometric phases provide the detailed relative height variations within a limit of $2{\pi}$ (or 15.3 cm) with respect to the sea level at the moment of the master data acquisition. A combined estimation results in an instantaneous sea level. The radar measurements were verified using tide gauge records, and the results yielded a correlation coefficient of 0.96 with an r.m.s. error of 6.0 cm. The results demonstrate that radar interferometry is a promising approach to sea level measurement in the near coastal regions.

• Journal of Korean Society for Quality Management
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• v.49 no.4
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• pp.539-550
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• 2021

Purpose: The purpose of this study is to propose a multivariate CUSUM control chart that can detect the out-of-control state fast while monitoring the cross- and auto- correlated multivariate time series data. Methods: We first build models to estimate the observation data and calculate the corresponding residuals. After then, a multivariate CUSUM chart is applied to monitor the residuals instead of the original raw observation data. Vector Autoregression and Artificial Neural Net are selected for the modelling, and Separated-MCUSUM chart is selected for the monitoring. The suggested methods are tested under a number of experimental settings and the performances are compared with those of other existing methods. Results: We find that Artificial Neural Net is more appropriate than Vector Autoregression for the modelling and show the combination of Separated-MCUSUM with Artificial Neural Net outperforms the other alternatives considered in this paper. Conclusion: The suggested chart has many advantages. It can monitor the complicated multivariate data with cross- and auto- correlation, and detects the out-of-control state fast. Unlike other CUSUM charts finding their control limits by trial and error simulation, the suggested chart saves lots of time and effort by approximating its control limit mathematically. We expect that the suggested chart performs not only effectively but also efficiently for monitoring the process with complicated correlations and frequently-changed parameters.

• Korean Journal of Schizophrenia Research
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• v.23 no.1
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• pp.15-28
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• 2020

Objectives: This study investigated the relationship between clock-drawing test (CDT) performance and neuropsychological functions in patients with chronic schizophrenia. Methods: Thirty-one patients with schizophrenia and 30 healthy controls participated in this study. The CDT was administered in three conditions and analyzed using both quantitative and qualitative scoring systems. Comprehensive neuropsychological tests were administered. Results: The results of the quantitative analysis showed that the schizophrenia group performed significantly worse in all three conditions of the CDT compared with the control group. However, no significant differences were observed between the two groups, when the IQ and educational level were controlled. The qualitative analysis showed that the schizophrenia group exhibited significantly more errors in "graphic difficulty" compared with the control group. In addition, CDT quantitative scores were significantly correlated with visuospatial function, memory, attention and executive functions in patients with schizophrenia. Conversely, each qualitative error type was correlated with specific cognitive domains. Furthermore, "graphic difficulty" and "spatial/planning deficit" were identified as predictors of depression symptoms in patients with schizophrenia. Conclusion: The present study demonstrated that the CDT is useful for assessing cognitive dysfunctions in patients with schizophrenia, while qualitative analyses provide more specific information about cognitive deficits compared with quantitative analyses.

• The Journal of the Acoustical Society of Korea
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• v.26 no.2
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• pp.69-74
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• 2007

In signal processing applications with highly correlated input signals, subband affine projection algorithm and step size controlling is a good solution for improving the slow convergence rate and large computational complexity of LMS-type algorithms. This paper proposes a subband affine projection algorithm using a variable step size. The proposed method achieves fast convergence rate and small steady-state error with a small computational complexity by combining the SAP and step size controlling in a subband structure. Experimental results on highly correlated input signal show that the proposed method is superior to the conventional methods.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.75-80
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• 2005

A new antenna shuffling scheme for double space time transmit diversity is proposed. The proposed method obtains the shuffling pattern directly from the estimated channel by maximizing minimum post-processing signal to noise ratio(SNR), while the conventional method minimizes channel correlation. Since the minimum post-processing SNR is directly related with error performance, the proposed method shows better bit error rate performance than the conventional method. Monte Carlo simulations showed that the proposed scheme has more 3 dB SNR gain than the conventional scheme for 10/sup -3/ bit error rate in spatially correlated fadingcaused by a single cluster model.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.4
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• pp.403-410
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• 2012

Purpose: The purposes of this study are to investigate accommodative response among emmetropes, spectacle wearer and contact lens wearer, and correlation between refractive error and accommodative respons for each group. Methods: The 72 subjects(144 eyes) who do not have any ocular diseases were participate in this study. Subjects were categorized into emmetropes, spectacle wearer and contact lens wearer by refractive error using closed-field auto-refractometer. We measured dominant eye, naked/habitual visual acuity and refractive error of monocular/binocular vision of refractive error for far/near distance with open-field auto-refractometer and calculated accommodative lag. Results: There were no significant difference of accommodative lag between right and left eye dominant and non-dominant eye, monocular and binocular vision, and spectacle lens wearer and contact lens wearer, However the accommodative lag of binocular vision was severe than monocular vision at near. The lag of myopia was larger than emmetropes, and male was larger than female. Significant correlation was found between refractive error and accommodative lag in total subjects and the same result was found in emmetropes and contact lens wearer. However there were no significant correlation in the spectacle wearer. Conclusions: There were significant difference between emmetrops and myopes in terms of accommodative lag, however accommodative lag of spectacle wearer was not different with contact lens wearer in myopes. There were also significant correlation between refractive error and accommodative lag in emmetropes and contact lens wearer, but the accommodative lag of spectacle wearer was not significantly correlated with refractive error.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.2
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• pp.115-126
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• 2017

There is an increasing concern over arsenic (As) contamination in rice. This study was conducted to develope a prediction model for As uptake by rice based on the physico-chemical properties of soil. Soil and brown rice samples were collected from 46 sites in paddy fields near three different areas of closed mines and industrial complexes. Total As concentration, soil pH, Al oxide, available phosphorus (avail-P), organic matter (OM) content, and clay content in the soil samples were determined. Also, 1.0 N HCl, 1.0 M $NH_4NO_3$, 0.01 M $Ca(NO_3)_2$, and Mehlich 3 extractable-As in the soils were measured as phytoavailable As concentration in soil. Total As concentration in brown rice samples was also determined. Relationships among As concentrations in brown rice, total As concentrations in soils, and selected soil properties were as follows: As concentration in brown rice was negatively correlated with soil pH value, where as it was positively correlated with Al oxide concentration, avail-P concentration, and OM content in soil. In addition, the concentration of As in brown rice was statistically correlated only with 1.0 N HCl-extractable As in soil. Also, using multiple stepwise regression analysis, a modelling equation was created to predict As concentration in brown rice as affected by selected soil properties including soil As concentration. Prediction of As uptake by rice was delineated by the model [As in brown rice = 0.352 + $0.00109^*$ HCl extractable As in soil + $0.00002^*$ Al oxide + $0.0097^*$ OM + $0.00061^*$ avail-P - $0.0332^*$ soil pH] ($R=0.714^{***}$). The concentrations of As in brown rice estimated by the modelling equation were statistically acceptable because normalized mean error (NME) and normalized root mean square error (NRMSE) values were -0.055 and 0.2229, respectively, when compared with measured As concentration in the plant.

• The Journal of Korean Academy of Sensory Integration
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• v.4 no.1
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• pp.1-15
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• 2006

Objective : The purpose of this study was to examine the correlation between handwriting skills and praxis. Method : Participants consisted of 50 normal children who were the second-grade students at an A elementary school in Kim-hae. They didn't have a visual dysfunction, an auditory dysfunction, and a disease or an injury in arms and hands. They could follow examiners' directions properly. They were administered the Postural Praxis and the Praxis on Verbal Command of the Sensory Integration and Praxis Tests(SIPT)(Ayres, 2000) and the handwriting skill test which was made with reference to foreign literatures. It was conducted from October 19, 2004 to December 17, 2004. The data were analyzed with non-paired t-test, ANOVA, and Pearson correlation coefficient. Results : 1. Total handwriting score and praxis according to gender of children showed the statistically significant differences(p<0.05). 2. Total handwriting score correlated with praxis(p<0.05) and handwriting speed did not correlate with praxis. 3. Postural Praxis and Praxis on Verbal Command according to handwriting groups showed the statistically significant differences(p<0.05). 4. Among the standards of the handwriting skill test, accuracy of letter form, identity of letter size, spacing between letters and words, placing text on lines, error existence, and letter out of regular square correlated with the Postural Praxis(p<0.05), and accuracy of letter form, identity of letter size, and placing text on lines correlated with the Praxis on Verbal Command(p<0.05). Conclusions : The correlation between handwriting skills and praxis will help occupational therapists to provide fundamental and various treatment programs for children who are referred for the poor handwriting. But more studies in handwriting skills and praxis are necessary to decide which component of handwriting skills is related to praxis.

• Journal of Biosystems Engineering
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• v.34 no.5
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• pp.382-389
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• 2009

An in-situ probe-based spectrophotometer has been developed. This system used two spectrometers to measure soil reflectance spectra from 450 nm to 2200 nm. It collects soil electrical conductivity (EC) and insertion force measurements in addition to the optical data. Six fields in Kansas were mapped with the VIS-NIR (visible-near infrared) probe module and sampled for calibration and validation. Results showed that VIS-NIR correlated well with carbon in all six fields, with RPD (the ratio of standard deviation to root mean square error of prediction) of 1.8 or better, RMSE of 0.14 to 0.22%, and $R^2$ of 0.69 to 0.89. From the investigation of carbon variability within the soil profile and by tillage practice, the 0-5 cm depth in a no-till field contained significantly higher levels of carbon than any other locations. Using the selected calibration model with the soil NIR probe data, a soil profile map of estimated carbon was produced, and it was found that estimated carbon values are highly correlated to the lab values. The array of sensors (VIS-NIR, electrical conductivity, insertion force) used in the probe allowed estimating bulk density, and three of the six fields were satisfactory. The VIS-NIR probe also showed the obtained spectra data were well correlated with nitrogen for all fields with RPD scores of 1.84 or better and coefficient of determination ($R^2$) of 0.7 or higher.

• Korean Journal of Biological Psychiatry
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• v.13 no.3
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• pp.191-201
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• 2006

Objectives : The purpose of this study was to investigate whether the cognitive functions would be correlated with psychotic symptoms and whether antipsychotic treatments would affect the cognitive functions after 8 weeks. Methods : The thirty-five schizophrenic patients were conducted in this study. The psychopathology was measured using PANSS. The memory function, executive function, and sustained attention were measured using Memory Assessment Scale(MAS), Wisconsin Card Sorting Test(WCST), and Vigilance(VIG) and Cognitrone(COG) in Vienna Test System. After 8 weeks of antipsychotic treatment, we retested the cognitive tests. Results : 1) The cognitive tests after the 8 week's treatment showed significant improvements in memory and executive function in the schizophrenic patients. On the other side, sustained attention did not show improvement. 2) The change of PANSS were correlated with perseverative response, perseverative error and total correct in WCST at baseline. WCST scores at baseline were correlated with negative symptoms, but not positive ones. Conclusion : These study suggests that 1) the impaired sustained attention could be a vulnerability marker in schizophrenia, 2) memory & executive function deficit could be reversible after treatment, and 3) medication might have a benefit in improving the cognitive functions in schizophrenia. Furthermore, the data supports that the better premorbid executive function was, the more favorable was the treatment response in schizophrenic patients. Finally, this study indicates that executive function might be an index of treatment improvement.