• The Korean Journal of Applied Statistics
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• v.21 no.3
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• pp.361-375
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• 2008

We propose proper methods to impute the item nonresponse in 4-8-4 rotation sample survey. We consider nonignorable nonresponse mechanism that can happen when survey deals with sensitive question (e.g. income, labor force). We utilize modeling imputation method based on Bayesian approach to avoid a boundary solution problem. We also estimate a interview time bias using imputed data and calculate cell expectation and marginal probability on fixed time after removing estimated bias. We compare the mean squared errors and bias between maximum likelihood method and Bayesian methods using simulation studies.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.233-238
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• 2014

Creativity is crucial in designing and producing attractive accessaries and daily supplies as well as art works. Generative design can be a paradigm to be used to obtain novel ideas or motifs for creative design works. This paper introduces a generative design method which comes up with unique ring models using genetic algorithm. It presents how the genetic algorithm works in terms of candidate solution coding, operators, and fitness evaluation function. The proposed method allows the customers to express their personal preference and later the preference to be reflected in fitness evaluation. In the final stage of the proposed method, several ring models are suggested for customers to choose on their own. The chosen ring models can be put into physical rings with the help of a 3D printer because the models are expressed in 3D geometric structures.

• Journal of the Korean Institute of Intelligent Systems
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• v.9 no.6
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• pp.650-656
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• 1999

In this paper, we study on the convergence of the evolution strategies by introducing the Lamarckian evolution and the Baldwin effect, and propose a random local searching and a reinforcement local searching methods. In the random local searching method some neighbors generated randomly from each individual are med without any other information, but in the reinforcement local searching method the previous results of the local search are reflected on the current local search. From the viewpoint of the purpose of the local search it is suitable that we try all the neighbors of the best individual and then search the neighbors of the best one of them repeatedly. Since the reinforcement local searching method based on the Lamarckian evolution and Baldwin effect does not search neighbors randomly, but searches the neighbors in the direction of the better fitness, it has advantages of fast convergence and an improvement on the global searching capability. In other words the performance of the evolution strategies is improved by introducing the learning, reinforcement local search, into the evolution. We study on the learning effect on evolution strategies by applying the proposed method to various function optimization problems.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.1
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• pp.62-66
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• 2017

The interest on the potential earthquake magnitude and the request on the earthquake-resistant design examination for coastal structures are emerged because of the recently occurred magnitude 5.8 earthquake in Gyeoung-Ju, Korea. In this study, the magnitude and its confidence intervals with the return periods are estimated using the KMA earthquake magnitude data (over 3.5 and 4.0 in magnitude) by the non-parametric extreme value analysis. In case of using the "over 4.0" data set, the estimated magnitudes on the 50- and 100-years return periods are 5.81 and 5.94, respectively. Their 90% confidence intervals are estimated to be 5.52-6.11, 5.62-6.29, respectively. Even though the estimated magnitudes have limitations not considering the spatial distribution, it can be used to check the stability of the diverse coastal structures in the perspective of the life design because the potential magnitude and its confidence intervals in Korea are estimated based on the available 38-years data by the extreme value analysis.

• KSCI Review
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• v.15 no.1
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• pp.37-46
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• 2007

Lately, is trend that diffusion of Mobile information appliance that do various function by development of IT technology is increasing much. There is function that do more convenient and efficient life and business using portable phone that is Daepyo?? of Mobile information appliance, but dysfunction that is utilized by Beopjoe of pointed end engineering data leakage, individual's privacy infringement, threat and threat etc. relationship means to use Mobile Phone is appeared and problems were appeared much. However, legal research of statute unpreparedness and so on need research and effort to prove delete, copy, integrity of digital evidence that transfer secures special quality of easy digital evidence to objective evidence in investigation vantage Point is lacking about crime who use this portable phone. It is known that this digital Forensic field is Mobile Forensic. Is purposeful to verify actually about acquisition way of digital evidence that can happen in this treatise through portable phone that is Mobile Forensic's representative standing and present way to prove integrity of digital evidence using Hash Function.

• Korean Journal of Food Science and Technology
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• v.21 no.5
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• pp.655-661
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• 1989

Optimal drying conditions consisting of air temperature and relative humidity were searched by the simulation-optimization technique for minimizing quality changes in red pepper drying. Optimized drying conditions were analysed in the viewpoint of quality change kinetics and effects of control variables on the state variables. Optimal drying conditions were nearly same in both cases for carotenoid maximization and browning minimization. In two staged optimized drying, relative humidity took a lower search limit of about 10%, and air temperature in the first stage was near the lower limit of $50^{\circ}C$ and in second stage increased to a higher temperature varying with total drying time and stage changing time. Response surface analysis of time invariable drying confirmed the location of the optimal point lying on the vertex of lower limit humidity and a lowest drying temperature which ensures to attain target moisture of 0.2g water/g dry solid. Two stage drying can attain the higher objective function of quality by 3-5% than time invariable drying for shorter total drying times.

• The Korean Journal of Applied Statistics
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• v.34 no.4
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• pp.589-597
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• 2021

In simple and multiple regression, there is a difference in the meaning of regression coefficients, and not only are the estimates of regression coefficients different, but they also have different signs. Understanding the relative contribution of explanatory variables in a regression model is an important part of regression analysis. In a standardized regression model, the regression coefficient can be interpreted as the change in the response variable with respect to the standard deviation when the explanatory variable increases by the standard deviation in a situation where the values of the explanatory variables other than the corresponding explanatory variable are fixed. However, the size of the standardized regression coefficient is not a proper measure of the relative importance of each explanatory variable. In this paper, the estimator of the regression coefficient in multiple regression is expressed as a function of the correlation coefficient and the coefficient of determination. Furthermore, it is considered in terms of the effect of an additional explanatory variable and additional increase in the coefficient of determination. We also explore the relationship between estimates of regression coefficients and correlation coefficients in various plots. These results are specifically applied when there are two explanatory variables.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.1-15
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• 2003

${Cachin}^{[1]}$ defined the security of steganography theoretically at first, then ${Katzenbeisser}^{[2]}$ and ${Hopper}^{[3]}$ also discussed it on the different aspects. Unfortunately, because many steganographic systems couldnt overcome the statistical gap between a stego-cover and a pure cover, the secure steganography hasn' been evaluated yet. By the effectivel steganalysis algorithm, statistical test which was suggested by Westfel $d^{［4］}$, the attacker Wendy could select the stego-covers out of suspicious covers. Our newly developed algorithm which minimizes the changes of a pure cover by using the block cipher withstands a statistical test and has a similar embedding capacity in comparison with a simple LSB substitution steganography.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.289-298
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• 2023

Stored rice grain undergoes physical and chemical deteriorations over time. As temperature and moisture content are important factors affecting to the denaturation of rice, it is important to store rice at a low temperature and hermetic condition. From a microscopic point of view, many studies have already reported how proteins and lipids were denatured within rice grain. Meanwhile, the weight loss of rice is currently observed at actual storage sites and can occur for diverse reasons. In this study, it was assumed that the decomposition process of polysaccharides, known as the main component of rice, plays an important role in its weight loss. In specific, the roles of enzymes were also evaluated. Our interest is in the major polysaccharides within a rice grain such as starch as well as within a rice endosperm cell wall. It is suspected that the weight loss of rice grains during storage seems to associate with the degradation of amylose and amylopectin. Nevertheless, it should be also speculated the correlating effect of other components such as proteins and lipids.

• Environmental and Resource Economics Review
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• v.26 no.2
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• pp.257-286
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• 2017

This paper estimates the effects of imaginary repeated increases in excise duties on fuel oil consumption and on their income redistribution according to changes in consumer price index, if the inflation indexation system was introduced right after the second Energy Tax Reform ended in July, 2007 in Korea. In fact, nominal excise rates have not been adjusted since 2007. As a result, the real excise rates on fuel oils have been diminished inversely proportional to the consumer price index. Own- and cross-price elasticities of fuel oils such as gasoline and diesel oil are estimated under the general equilibrium framework based on the linear expenditure system. Counterfactual analyses through microsimulation in a static model are adopted to estimate the effects of introducing inflation indexation into the fuel tax in 2007 when the second Energy Tax reform ended on the fuel consumption and income redistribution in 2014. Microsimulations suggest that its introduction could have reduced the consumption of gasoline and diesel oil by 8.8% and 5.4%, respectively, ending up with increased excise revenue by 11.9%. The revenue increase in spite of decreased consumption is mainly because their demands are price inelastic. It could also have increased positive income redistributive effect by 0.01%p (from 0.12% to 0.13%), which is measured in terms of percentage decrease in Gini coefficient. In other words, the fuel excise on the two fuel oils decreased by 0.13% the Gini coefficient of before and after fuel tax income in 2014. This implies that the inflation indexation could have enlarged the income redistributive effect up to 0.13% in 2014, if it is introduced in 2007.