• The Korean Journal of Applied Statistics
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• v.23 no.1
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• pp.13-28
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• 2010

Assuming a mixture distribution for credit evaluation studies, we discuss estimating threshold methods to minimize errors that default borrowers are predicted as non defaults or non defaults are regarded as defaults. A method by using statistical hypotheses tests, the most powerful test and generalized likelihood ratio test, for the probability density functions which are defined with the score random variable and the parameter space consisted of only two elements such as the default and non default states is proposed to estimate a threshold. And anther optimal thresholds to maximize classification accuracy measures of the accuracy and the true rate for ROC and CAP curves are estimated as equations related with these probability density functions. Three kinds of optimal thresholds in terms of the hypotheses testing, the accuracy and the true rate are obtained from normal random samples with various means and variances. The sums of the type I and type II errors corresponding to each optimal threshold are obtained and compared. Finally we discuss about their efficiency and derive conclusions.

• Communications for Statistical Applications and Methods
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• v.15 no.4
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• pp.531-542
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• 2008

The unit root test is the major tool for determining whether we use differencing or detrending to eliminate the trend from time series data. Dickey-Fuller test (Dickey and Fuller, 1979) has the low power of test when the sample size is small or the true coefficient of AR(1) process is almost unit root and the Bayesian unit root test has complicated testing procedure. We propose a new unit root testing procedure, which mixed Bayesian approach with the traditional testing procedure. Using simulation studies, our approach showed locally higher powers than Dickey-Fuller test when the sample size is small or the time series has almost unit root and simpler procedure than Bayesian unit root test procedure. Proposed testing procedure can be applied to the time series data that are not observed as process with unit root.

• Communications for Statistical Applications and Methods
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• v.17 no.3
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• pp.413-421
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• 2010

In this study, we considered bivariate conditional auto-regressive model taking into account spatial association as well as correlation between the two dependent variables, which are the counts of murder and burglary. We conducted likelihood ratio test for checking over-dispersion issues prior to applying spatial poisson models. For the real application, we used the annual counts of violent crimes at 25 districts of Seoul in 2007. The statistical results are visually illustrated by geographical information system.

• The Transactions of the Korea Information Processing Society
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• v.3 no.2
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• pp.225-230
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• 1996

We propose a statistical test for the nonlinear combiner logics which are usually combined with two maximal Linear Feedback Shift Registers and generate pseudorandom bit sequences. This test uses the mutual information between the output and set of inputs which will be a random variable and its distribution is obeyed to an approximate $\{chi}^2$ -distribution. We adopt this statistic to a $\{chi}^2$ -test of independence by using contingency table. We also apply a proposed test to some non-linear crptosystems and show that this useful to evaluate the strength of the cryptosystems.

• Korean Journal of Weed Science
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• v.9 no.1
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• pp.69-75
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• 1989

To search germination inhibitors in higher plants, first of all, some experiments containing selection of test weed seeds and effects of solvents and surfactants for bioassay establishment were conducted. Then MeOH-extracts of 45 plants were assayed for germination inhibition activities against Echinochloa crus-galli (L.) Beauv, Digitaria sanguinalis (L.) Scop., Cyperus iria L., Portulaca oleracea L. and Oenothera lamarckiana Ser. seeds. Among them extracts from Rhathiolepis ovata Briat and Picea abies (L.) Karst showed strong inhibitory effect (60-90% inhibition) on the germination of tested weed seeds at 5000 ppm. On the other hand, the extract from Youngia sonchifolia Max stimulated the germination and growth of tested weeds.

• The Korean Journal of Pesticide Science
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• v.7 no.1
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• pp.32-37
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• 2003

Bacterial soft rot by Erwinia carotovora subsp. carotovora is one of the diseases causing the biggest problem in Chinese cabbage. Chemical screening was conducted to select effective agents for controlling bacterial soft rot. Control effect of antibiotics, plant activator, and Biokeeper (avirulent Erwinia) to soft rot were tested by in vitro assay, nursery test, and field experiment. The in vitro assay was done by paper disc method and potato slice method. The nursery test was performed by using mineral oil inoculation method with consistent disease induction. The in vitro assay showed that streptomycin, oxolinic acid, bronopol, and copper hydroxide significantly suppressed the growth of pathogenic bacterium and the decomposition of potato slice. However, plant activators including acibenzolar-S-methyl did not show the suppressive effect on the growth of pathogenic bacterium and the decomposition of potato slice. When applied by the nursery test condition using mineral oil inoculation method with Chinese cabbage 'Kangruckyeurum', Biokeeper, oxolinic acid, antibiotics streptomycin, validamycin, and copper compound provided 83.5%, 95.2%, 91.2%, 57.5% and 79.9% in control efficacy, respectively. However, the control effect of acibenzolar-S-methyl showed to be low to cause phytotoxicity. Also acibenzolar-S-methyl showed a significant control effect in the field experiment with Chinese cabbage 'Sanchon' in 2000, but the field experiment with Chinese cabbage 'Kangruckyeurum' in 2001 revealed it had phytotoxicity to Chinese cabbage. Such a difference was considered to be caused by differences in phytotoxic reaction of Chinese cabbage cultivars to the chemical. Streptomycin+copper, copper hydroxide and Biokeeper showed 79.7%, 71.9% and 60.9% in control efficacy, respectively, in the field experiment with Chinese cabbage 'Sanchon' in 2002.

• The Mathematical Education
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• v.52 no.3
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• pp.363-377
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• 2013

교수효능감은 교사가 교실에서 얼마나 효율적으로 가르칠 것인지를 예측하는 매우 강력한 구인이다. MTEBI는 초등 예비교사를 대상으로 수학 교수 효능감을 재는 유효한 척도이다. 그러나 MTEBI는 미국에서 개발되어 다른 문화에서 바로 사용할 수는 없다. 본 연구는 MTEBI가 한국에서 유효한 지에 대한 실증적 조사이다. 먼저, 영문의 MTEBI를 국문으로 번역하고, 번역한 것을 다수의 수학교사 교육자가 철저하게 검토하였다. 그다음, 506명의 예비 초등교사 표본에서 정규성, 신뢰도, 타당도 등의 통계적 검정을 실시하였다. 그 결과, 한글판 MTEBI의 하위척도인 PMTE와 MTOE의 알파계수가 각각 .836과 .705이었다. 이로써 한글판 MTEBI가 한국에서 효능감 연구에 사용할 수 있을 만큼 믿을 수 있고 문항 구성이 타당함을 입증하였다. 나아가 본 연구에서 제시된 영문판을 바탕으로 한국과 교육에 대한 전통과 문화가 비슷한 이웃 문화에서도 효능감 연구가 일어나기를 기대한다.

• The Journal of the Korea Contents Association
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• v.18 no.2
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• pp.26-36
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• 2018

The purpose of this study is to verify the self-respect moderating effect on adolescents with emotional problems because of neglect and abusive experiences. The results are as follows: First, the level of abusive experiences was higher than that of neglect in adolescents. General characteristics including genders and individual family situations were found to be the influences causing emotional problems in adolescents. Second, adolescents with high levels of neglect and abuse experienced high levels of depression, social anxiety, aggression and physical symptoms. Third, even though self-respect did not have a strong moderating effect on the emotional problems of adolescents who suffered neglect and abuse, there was a difference between the abuse experience and the emotional problem in the inclination test results for the high and low group based on the average of the self-respect of the respondents. The results of this study suggest that the need for a stronger variable to reduce the negative emotional state among adolescents experiencing neglect and abuse is related to emotional problems.

• Korean Journal of Food Science and Technology
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• v.49 no.3
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• pp.331-337
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• 2017

To evaluate the antioxidant activity of hexane, ethyl acetate, and butanol fractions obtained from Agastache rugosa extract, we measured the total polyphenol levels, DPPH radical scavenging activity, and reducing power. The ethyl acetate fraction of A. rugosa (AREA) displayed high phenolic levels, potent DPPH radical scavenging effect, and powerful reducing power. In addition, we examined the ability of AREA to inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV-2 microglia. AREA suppressed NO production and inducible nitric oxide synthase (iNOS) expression and downregulated interleukin-6 (IL-6) mRNA level in LPS-stimulated BV-2 microglia. Furthermore, we detected rosmarinic acid in AREA by HPLC, which suggested that rosmarinic acid could be one of the bioactive materials responsible for the antioxidant and anti-inflammatory activities of AREA. These results suggested that AREA may be a good source of functional foods with antioxidant and anti-inflammatory activities.

• Journal of Energy Engineering
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• v.29 no.1
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• pp.1-12
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• 2020

The rapid climate change is strengthening carbon emissions regulations internationally. Korea is strongly pressed to accept the obligation to reduce greenhouse gases as one of the United Nations Framework Convention on Climate Change. This article analyzed the Granger causalities among environmental regulation, economic growth, electricity consumption, and CO₂ emission in Korea, using unit root test, cointegration test, and vector error correction model. As the results, environmental regulation has shown the bidirectional causalities with electricity consumption and CO₂ emission, while being unilaterally affected by economic growth in the long-run and strong relationship. Economic growth has affected electricity consumption, CO2 emission, and environmental regulation in the long-run, in the complex structure of the unilateral and short-run causality with electricity consumption and the bidirectional causality with CO2 emission. The policy implications will be as follows: ① environmental regulation should induce sustainable growth through encouraging technological innovation relating to CO2 reduction and productivity enhancement. ② Responding to the international CO2 reduction regulation, the synthetic policy initiatives will be considered to make synergy effects among policies relating to economic growth, electricity consumption.