• Communications for Statistical Applications and Methods
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• v.19 no.1
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• pp.13-22
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• 2012

Cut-off sampling that discards a part of the population from the sampling frame, is a widely used method for a business survey. Usually, to the estimate of population total, an accurate estimate of the total of the take-nothing stratum is required. Many estimators have been developed to estimate the total of the take-nothing stratum. Recently Kim and Shin (2011) suggested a composite estimator and showed the superiority of that estimator. In this paper, we suggest an alternative composite estimator obtained by combining BLUP estimator and a ratio estimator obtained by the small samples from the take-nothing stratum. Small simulation studies are performed for a comparison of the estimators and we confirm that the new suggested estimator is superior.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.3
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• pp.355-367
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• 2007

This paper proposes a design method of the PI(Proportional-Integral)+D(Derivative) controller using self-tuning of the design variables and controller gains. The used fuzzy PI+D controller is the approximated conventional continuos time linear PI+D controller and the used fuzzification method is the fuzzy single tone and the adapted defuzzification method is the simplified tenter of gravity. Fuzzy estimation result would be calculated in the other function elements from the classified fuzzy variables and the result determined by the design variables decides the controller gains. As a result, the proposed method shows the capability of the high speed tuning and can be applied to the case of input variables with many fuzzy partitions and also can bring out the advantage to reduce the reconstruction(digital sampling reconstruction) error. Most simulation results show that this controller makes much bettor efficiency and improvement by using design variables and controller gains.

• Journal of Applied Biological Chemistry
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• v.65 no.1
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• pp.17-21
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• 2022

A new rapid and simple method for metalaxyl in Atractylodes macrocephala Koidzumi and Achyranthes japonica Nakai has been developed and validated. This study was conducted to develop a method for analyzing metalaxyl by a method based on QuEChERS using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Samples were extracted with acetonitrile and purified using amino-propyl (NH₂) Solid Phase Extraction cartridge. The method limit of quantitation (MLOQ) was 0.01 mg/kg. The linearity of matrix-matched calibration curve (r²) was ≥0.99 at the calibration range of 0.001-0.05 mg/kg. For recovery test, Atractylodes macrocephala Koidzumi or Achyranthes japonica Nakai was treated with standard solutions at MLOQ and 10MLOQ levels. Recovery rates were in the range of 88.1-109.1% with <5.5% coefficient of variation. This established analytical method was fully validated. Based on these results, it can contribute to improving the safety of residual pesticides in Atractylodes macrocephala Koidzumi and Achyranthes japonica Nakai.

• Journal of the Korean Geotechnical Society
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• v.24 no.9
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• pp.13-21
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• 2008

Partitioning tracer method is a useful tool to characterize large domains of the aquifers contaminated with light nonaqueous phase liquids (LNAPLs). Sorption of the partitioning tracers to the organic matter content of soil can potentially influence the efficacy of partitioning tracer method. LNAPL-water partitioning coefficients of tracers ($K_{nw}$), measured by static method, showed linear relationship. Sorption isotherm tests were conducted to evaluate the sorption capacity of the soils packed in the columns and the results were appropriately represented by Freundlich sorption isotherm. The sorption of tracers proportionally increased with the increase of the organic matter content of the soil. Laboratory experiments were conducted in four columns each packed with soils of different organic matter contents to determine the potential interference effects of sorption to soil organic matter content and correction factors for the errors in estimation of LNAPLs by partitioning tracer method. Though there were no contaminants added, breakthrough curves from columns packed with mixture of Jumunjin standard sand and organic matter showed separation of tracers. Columns were then contaminated to residual saturation with kerosene and breakthrough curves were obtained. The results show that sorption of tracers to soil organic matter leads to an increase in the retardation factor (R) and hence, to an overestimation of the saturation of LNAPLs. A relation between the percentage of organic matter content and the corresponding percentage error in the estimation of NAPLs has been developed.

• The Korean Journal of Pesticide Science
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• v.16 no.3
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• pp.202-208
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• 2012

A high-performance liquid chromatographic (HPLC) method was developed to determine residues of cyromazine, a triazine insecticide, in agricultural commodities. Cyromazine was extracted with 90% aqueous methanol from representative crops which comprised brown rice, oyster mushroom, oriental melon, watermelon, and Chinese cabbage. Following to evaporation of methanol in the extract, the aqueous concentrate was acidified to form the protonated cyromazine. Dichloromethane partition was then applied to remove nonpolar co-extractives in the aqueous phase. Strong cation-exchange chromatography using Dowex 50W-X4 resin was employed for final purification of the extract. Cyromazine was successfully separated on a Zorbax SB-Aq $C_{18}$ column showing high retention for polar compounds. Cyromazine was sensitively quantitated by ultraviolet absorption at 214 nm. Limit of quantitation (LOQ) of the method was 0.04 mg/kg irrespective of sample types. Each crops were fortified at 3 different concentrations of cyromazine for recovery test. Mean recoveries from samples fortified at LOQ~2.0 mg/kg in triplicate ranged 80.2~103.3% in five agricultural commodities. Relative standard deviations in recoveries were all less than 6%. A selected-ion monitoring LC/MS method with electrospray ionization in positive-ion mode was also provided to confirm the suspected residue. The proposed method was reproducible and sensitive enough to routinely determine and inspect the residue of cyromazine in agricultural commodities.

• Korean Journal of Microbiology
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• v.44 no.2
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• pp.130-134
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• 2008

Modern automated culture systems have increased the isolation rate of microorganisms and shortened the time to detection, reducing experimental errors in diagnosis of infecting agents. BacT/ALERT 3D system is based on the colorimetric detection of $CO_2$ produced by the growing microorganisms. In order to evaluate the efficiency of the detection system, sterility test were performed using 6 bacteria. With standard aerobic and anaerobic bottles containing the liquid media, both three aerobic bacteria (P. aeruginosa, M. luteus, B. subtilis) and a facultative bacterium S. aureus were detected up to 1 CFU in 31.44 hr. In addition, growth of anaerobic C. sporogenes was recognized up to 1 CFU in 15.96 hr. The slowly growing bacteria P. acnes was detected up to 10,000 CFU in 129.36 hr. In comparison with conventional culture method, BacT/ALERT 3D automated culture system was more sensitive and saved detection time up to$2\sim10$ hr. Therefore, this automated culture system enables to efficiently detect bacteria in clinical samples and biological medicines.

• Korean Journal of Plant Resources
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• v.27 no.4
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• pp.286-292
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• 2014

Near infrared reflectance spectroscopy (NIRS) is a rapid and accurate analytical method for determining the composition of agricultural products and feeds. This study was conducted to measure baicalin, baicalein, and wogonin contents in Scutellaria baicalensis by using NIRS system. Total 63 samples previously were analyzed by HPLC, which showed baicalin, baicalein, and wogonin contents ranging 4.56 to 13.59%, 0.28 to 5.54%, and 0.50 to 1.63% with an average of 9.66%, 2.09% and 0.52%, respectively. Each sample was scanned by NIRS and calculated for calibration and validation equation. A calibration equation calculated by modified partial least squares(MPLS) regression technique was developed in which the coefficient of determination for baicalin, baicalein, and wogonin content was 0.958, 0.944, and 0.709, respectively. Each calibration equation was applied to validation set that was performed with the remaining samples not included in the calibration set, which showed high positive correlation both in baicalin and baicalein content file. In case of wogonin, the prediction model was needed more accuracy because of low $R^2$ value in validation set. These results demonstrate that the developed NIRS equation can be practically used as a rapid screening method for quantification of baicalin and baicalein contents in Scutellaria baicalensis.

• Geophysics and Geophysical Exploration
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• v.15 no.2
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• pp.85-91
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• 2012

Multiple Lapse Time Window (MLTW) analysis for obtaining intrinsic attenuation value require numerous data without directional bias to compensate focal mechanism. The first window of MLTW, therefore, shows large deviation in fitting smoothed theoretical curve. The information on the focal mechanism may reduce burdens of number and distribution. This study combined algorithm of computing focal mechanism to DSMC method by Yoshimoto (2000). However, the MLTW method based on the numerous data was not applicable to this study, because of the limited data to the almost same fault plane solution. This study showed that the available data was too insufficient to construct smoothed theoretical curve, although the deviation of the first window was improved. Instead of conventional solution by more data, the study seems to be needed for new constraints to obtain smoothed curve.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1145-1158
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• 1994

A three-dimensional, finite difference, numerical model with free surface was developed on ${\sigma}$-coordinate. A semi-implicit numerical scheme in time has been adopted for computational efficiency. The scheme is essentially independent of the stringent stability criteria (CFL condition) for explicit schemes of external surface gravity wave. Implicit algorithm was applied for vertical shear stress, Coriolis force and pressure gradient terms. The reliability of the model with vertically variable grid system was checked by the comparison of simulation results with analytic solution of wind-driven currents in a one-dimensional channel. Sensitivity analysis of differencing parameters was carried out by applying the model to the calculation of wind-driven currents in a square lake.

• Journal of the Korean Data and Information Science Society
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• v.27 no.1
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• pp.111-120
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• 2016

In usual, the discontinuous variance function was estimated nonparametrically using a kernel type estimator with data sets split by an estimated location of the change point. Kang et al. (2000) proposed the Gasser-$M{\ddot{u}}ller$ type kernel estimator of the discontinuous regression function using the adjusted observations of response variable by the estimated jump size of the change point in $M{\ddot{u}}ller$ (1992). The adjusted observations might be a random sample coming from a continuous regression function. In this paper, we estimate the variance function using the Nadaraya-Watson kernel type estimator using the adjusted squared residuals by the estimated location of the change point in the discontinuous variance function like Kang et al. (2000) did. The rate of convergence of integrated squared error of the proposed variance estimator is derived and numerical work demonstrates the improved performance of the method over the exist one with simulated examples.