• The Korean Journal of Applied Statistics
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• v.31 no.1
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• pp.123-137
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• 2018

A nonlinear mixed effects model is mainly used to analyze repeated measurement data in various fields. A nonlinear mixed effects model consists of two stages: the first-stage individual-level model considers intra-individual variation and the second-stage population model considers inter-individual variation. The individual-level model, which is the first stage of the nonlinear mixed effects model, estimates the parameters of the nonlinear regression model. It is the same as the general nonlinear regression model, and usually estimates parameters using the least squares estimation method. However, the least squares estimation method may have a problem that the estimated value of the parameters and standard errors become extremely large if the assumed nonlinear function is not explicitly revealed by the data. In this paper, a new estimation method is proposed to solve this problem by introducing the ridge regression method recently proposed in the nonlinear regression model into the first-stage individual-level model of the nonlinear mixed effects model. The performance of the proposed estimator is compared with the performance with the standard estimator through a simulation study. The proposed methodology is also illustrated using quantitative high throughput screening data obtained from the US National Toxicology Program.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.4
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• pp.265-270
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• 1993

The symbiotic dynamics of Bradyrhiwbium japonicum YCK strains indigenous to Korean soils were investigated accordingly to their competitive conditions for nodulation. For this experiment the single strain inoculants of YCK strains and the mixed inoculants of one YCK strain and one USDA strain were applied to Korean Jangbaekkong and American Clark soybeans at mollisol soils(Torroxic Haplustoll, pH 6.8). The results were summarized as follows : 1. The symbiotic effectiveness of B. japonicum YCK strains was increased on the average of nitrogen accumulation by mixing with USDA strains, especially with strain USDA 110. 2. The effectiveness of each mixed inoculant was affected by soybean cultivar. 3. YCK strains occupied on the average of 83 and 86 % of the nodules against strain USDA 110 on Jangbaekkong and Clark soybeans, respectitvely. 4. The most effective strain among three YCK strains was strain YCK 213 as a single inoculant and was strain YCK 141 as a mixed inoculant with USDA strains. 5. The mixed inoculants of YCK strains and strain USDA 123 showed antagonism for nodulation.

• Korean journal of applied entomology
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• v.43 no.1
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• pp.55-60
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• 2004

This experiment was conducted to improve activity of Spodoptera litura Nucleopoly-hedrovirus (SINPV) combined with organic and functional matters. In combination of SINPV mixed with organic matters, LT$_{50}$ values of SINPV 1.0${\times}$10$^{5}$ PIBs/$m\ell$ combined with boric acid of 2,000 ppm were 4.5 days. It was 1.5 days shorter than SINPV 1.0${\times}$10$^{5}$ PIBs/$m\ell$ alone. The body weight of larva infected with SINPV 1.0${\times}$10$^{5}$ PIBs/$m\ell$ combined with boric acid of 2,000ppm was not increased, and S. litura was completely dead in 7 days after treatment. It suggested that addition of boric acid in SINPV application enhanced the pathogenicity against S. litura larvae. In laboratory experiment of combination of SINPV with functional matters, LT$_{50}$values of SINPV 1.0${\times}$10$^4$ PIBs/$m\ell$ alone were 7.3 days, but those of SINPV 1.0${\times}$10$^4$ PIBs/$m\ell$ with electrolyzed oxidizing water, pyroligneous liquor or kitosan were 10.4, 9.3 and 11.2 days, respectively. Functional matter could be suppressed the insecticidal activity of SINPV

• Journal of Korea Soil Environment Society
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• v.3 no.1
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• pp.31-44
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• 1998

The geochemical experiments were carried out to investigate a removal effect of heavy metals in abdndoned metallic mine wastes, and to conceive a treatment techniques of them. In order to prevent contamination, experiment appature was made of acrylic acid resin and polyethylene which resist to acid and alkali. Experiment models are devided into four groups based on the system environments, distribution patterns and a kind of filling materials. The first group is background model(model I ) which is filled with waste only and opened to air. The second one is four layer group which is subdivided into two models, opened and closed systems, and the third mix group which is subdivided into three models based on mixing ratio of filling materials and system environment like a layered group. The forth is composed of two layer model, lower one composed of waste and upper one limestone chips. Solution drained from Model Ishows a high contents of heavy metals on the all terms of experiments. Among the models, however, the closed mix model V and Ⅶ show the most effective removal of heavy metals liberated from wastes. Models having different mixing ratios of filling materials on closed systems does not affect in heavy metal removal effect. But, the distribution patterns of filling materials affect very much on removal effect of heavy metals. The closed models with same constitution ratios and distribution patterns of filling materials show more and less effective removal to the open models.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.23-29
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• 2003

In this paper, effects of the acidification of ground and the chemical additive materials-ferric oxide, calcium chloride and calcium sulphate on the compressibility characteristics of the marine clay treated with quick lime were investigated. The rapid inflection point method was carried out. Results showed that the compression index of the untreated marine clay increased as the pH of pore water decreased. Also, the preconsolidation pressure, the coefficient of consolidation and the coefficient of permeability of the untreated marine clay decreased with pH of pore water. In the case of the marine clay treated with the quick lime-calcium chloride, the compression index decreased and the coefficient of consolidation and the coefficient of permeability increased. Specially, the preconsolidation pressure of sample treated with the quick lime-ferric oxide was higher than that of another samples.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.6
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• pp.814-822
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• 2012

To improve the flow and mixing characteristics of marine SCR system, two different mixer including up-down and swirl type mixer were considered. The purpose of this study is to analyse turbulence intensity and uniformity index in detail and to improve the performance of SCR with respect to the mixer structure. The results showed that, the concentration uniformity index is improved by about 5% with the utilization of both mixers in the front of catalyst part. Although the RMS value and relative turbulence intensity increased after the up-down type mixer, it could observed that the value of two parameters decreased with the flow proceeding forward to the downstream. For the case of swirl type mixer, the decrease of RMS value and relative turbulence intensity were relatively smaller than that of up-down type mixer, and uniform distribution of relative turbulence intensity was observed. As a results, it could be concluded that the mixing effects and the distance of the two kinds of mixer were different.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.677-684
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• 2013

A mixed refrigerant cycle (MRC) has been widely used in liquefaction of natural gas because it is simple and easily operable with reasonable equipment costs. One of the important techniques in MRC is selection of a refrigerant mixture and decision of its optimum mixing ratio. In this work, it is examined whether mixture components (refrigerants) and their mixing ratio influence performance of general MRC processes. In doing this, mixture design and response surface method, which are well-known statistical techniques, are used to find optimal mixture refrigerants and their optimal mixing ratio that minimize total energy consumption of the entire liquefaction process. A MRC process using several refrigerants and various mixing ratios is simulated by Aspen HYSYS and mixture design and response surface method are implemented using Minitab. According to the results, methane ($C_1$), ethane ($C_2$), propane ($C_3$) and nitrogen ($N_2$) are selected as best mixture refrigerants and the determined mixture ratio (mole ration) can reduce total energy consumption by up to 50%.

• Journal of the Korean Geotechnical Society
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• v.29 no.9
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• pp.81-91
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• 2013

This paper investigates the shear properties of bottom ash-crumb rubber mixture reinforced with waste fishing net. Mixtures used in this experiment were prepared at 2 different percentages of crumb rubber (2 mm~10 mm) content (i.e., 0%, 50% by weight of the dry bottom ash). In this study several series of triaxial tests were carried out on the six different specimens : unreinforced bottom ash, reinforced bottom ash with 1 or 2 layers, unreinforced mixture, reinforced mixture with 1 or 2 layers. The experimental results indicated that the shear properties of bottom ash-crumb rubber mixture were strongly influenced by reinforcing layer of waste fishing net and crumb rubber addition. It is shown that the internal friction angle of bottom ash-crumb rubber mixture decrease with addition of crumb rubber due to the compression properties of crumb rubber. However, the internal friction angle of the mixture increased with an increase in reinforcing layer due to interlocking effect and friction between mixture and waste fishing net.

• The Korean Journal of Applied Statistics
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• v.23 no.3
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• pp.511-520
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• 2010

The Pharmacokinetic model is a complex nonlinear model with pharmacokinetic parameters that is some-times represented by a complex form of differential equations. A population pharmacokinetic model adds individual variability using the random effects to the pharmacokinetic model. It amounts to the nonlinear mixed effect model. This paper, reviews the population pharmacokinetic model from a statistical viewpoint; in addition, a population pharmacokinetic model is also applied to the real clinical data along with a review of the statistical meaning of this model.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.10a
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• pp.276-279
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• 2005

본 연구는 가루녹차를 첨가한 기능성 요구르트를 개발하기 위한 기초 연구로 가루녹차의 농도별 첨가가 요구르트 균주의 증식 및 산 생성에 미치는 영향을 조사하였다. 단독균주의 경우 가루녹차의 첨가 농도를 달리하였을 때 Streptococcus thermophilus와 Lactobacillus casei는 가루녹차 첨가에 의해 증식 효과는 아주 미비하였으나 억제 효과가 나타나지 않았으며, Lactobacillus acidophilus는 배양 9시간부터 가루녹차 첨가구에서 대조구에 비해 높은 균수를 보이며 약간의 생육 촉진 효과를 보였고, 배양 12시간부터 pH가 하락하였으며 적정산도는 상승하였다. 그러나 가루녹차의 첨가량에 따른 생육과 산 생성 정도에 미치는 영향의 차이는 뚜렷하지 않았다. 혼합균주의 경우 단독균주로 배양하였을 때보다 가루녹차에 의한 유산균의 증식이 촉진되며, pH 저하와 적정산도 상승이 뚜렷하였다. 따라서 가루녹차 첨가 기능성 요구르트 제조 시 가루녹차를 0.5%${\sim}$l.0% 첨가하여 유산균을 혼합균주로 사용하는 것이 이들 유산균의 증식에 가장 적합한 것으로 나타났다.