• Proceedings of the Korean Statistical Society Conference
• /
• 2002.05a
• /
• pp.119-125
• /
• 2002

우리는 본 논문에서 디지털 영상에 대하여 Hash함수를 이용한 내용기반의 안전한 워터마킹 인증기술을 제시하려고 한다. 허가되지 않는 이미지의 내용변경을 막기 위해 안전한 워터마킹 시스템을 개발하기 위하여 비밀키를 가지고 있는 Hash 함수가 사용되었고, 각 블록의 워터마크신호는 Hash함수의 출력결과를 Seed로 사용하여 의사난수를 발생시킨 값에 따라 생성되어진다. 이미지 기술벡터들은 블록기반 에지 이미지로부터 측정되는데 이 값들은 해롭지 않는 조작 등에 대해서는 쉽게 변화하지 않지만 고의적인 내용변경 등의 조작에 대해서는 이들 값들이 바꾸어지는 성질을 갖고 있다. 워터마크신호의 삽입은 블록기반 스펙트럼 방법에 기초를 두고 있으며 워터마크신호의 크기는 인지성과 강인성이 조화를 이루도록 AC 부 밴드의 지그재그 스캔라인의 DCT 계수들의 지역적인 통계량에 따라 조정되어진다. 또한 저작권인증의 확인을 위한 경계 값의 선택은 통계학적으로 분석되어진다. 수치적인 실험의 결과는 제안된 기술이 강력한 저작권인증의 수행을 위해서 매우 효율적인 것을 보여주고 있다.

• Proceedings of the Korean Statistical Society Conference
• /
• 2003.10a
• /
• pp.263-268
• /
• 2003

Breiman, Friedman, Olshen and Stone(1984)의 전체탐색법에 의한 회귀나무는 상대적으로 많은 분리가 가능한 변수로 분리기준이 정해지는 편의 현상을 갖고 있다. 본 연구에서는 이런 문제점을 해결할 수 있는 알고리즘을 제안하여 변수선택편의가 없는 회귀나무를 만들고자 한다. 제안하는 알고리즘은 노드의 분리변수를 선택하는 단계와 그 선택된 변수에 의해 이진분리를 위한 분리점을 찾는 단계로 구성되어 있다. 예측변수 중에서 목표변수와 가장 밀접하게 연관된 예측변수는 예측변수의 자료의 종류에 따라 스피어만의 순위상관계수에 의한 검정 혹은 크루스칼-왈리스의 통계량에 의한 검정을 수행하여 가장 통계적으로 유의한 변수로 선택하였고, 선택된 변수에만 Breiman et al.(1984)의 전체선택법을 적용하여 분리점을 결정하였다. 모의실험을 통해 변수선택편의, 변수선택력 , 그리고 평균제곱오차 측면에서 Breiman et al. (1984)의 CART(Classification and Regression Trees)와 제안한 알고리즘을 서로 비교하였다. 또한, 두 알고리즘을 실제 자료에 적용하여 효율을 서로 비교하였다.

• The Korean Journal of Applied Statistics
• /
• v.17 no.3
• /
• pp.459-473
• /
• 2004

It has well known that an exhaustive search algorithm suggested by Breiman et. a1.(1984) has a trend to select the variable having relatively many possible splits as an splitting rule. We propose an algorithm to overcome this variable selection bias problem and then construct unbiased regression trees based on the algorithm. The proposed algorithm runs two steps of selecting a split variable and determining a split rule for binary split based on the split variable. Simulation studies were performed to compare the proposed algorithm with Breiman et a1.(1984)'s CART(Classification and Regression Tree) in terms of degree of variable selection bias, variable selection power, and MSE(Mean Squared Error). Also, we illustrate the proposed algorithm with real data sets.

• Journal of the Korean Data and Information Science Society
• /
• v.28 no.1
• /
• pp.87-98
• /
• 2017

The multivaiate empirical distribution function (MEDF) is defined in this work. The MEDF's expectation and variance are derived and we have shown the MEDF converges to its real distribution function. Based on random samples from bivariate standard normal distribution with various correlation coefficients, we also obtain MEDFs and propose two kinds of graphical methods to visualize MEDFs on two dimensional plane. One is represented with at most n stairs with similar arguments as the step function, and the other is described with at most n curves which look like bivariate quantile vector. Even though these two descriptive methods could be expressed with three dimensional space, two dimensional representation is obtained with ease and it is enough to explain characteristics of bivariate distribution functions. Hence, it is possible to visualize trivariate empirical distribution functions with three dimensional quantile vectors. With bivariate and four variate illustrative examples, the proposed MEDFs descriptive plots are obtained and explored.

• Journal of the Korean Data and Information Science Society
• /
• v.28 no.5
• /
• pp.959-970
• /
• 2017

In this study, we propose bivariate skewness and kurtosis statistics and suggest a surface plot that can visually implement bivariate data containing the correlation coefficient. The skewness statistic is expressed in the form of a paired real values because this represents the skewed directions and degrees of the bivariate random sample. The kurtosis has a positive value which can determine how thick the tail part of the data is compared to the bivariate normal distribution. Moreover, the surface plot implements bivariate data based on the quantile vectors. Skewness and kurtosis are obtained and surface plots are explored for various types of bivariate data. With these results, it has been found that the values of the skewness and kurtosis reflect the characteristics of the bivariate data implemented by the surface plots. Therefore, the skewness, kurtosis and surface plot proposed in this paper could be used as one of valuable descriptive statistical methods for analyzing bivariate distributions.

• 한국벤처창업학회:학술대회논문집
• /
• 2018.11a
• /
• pp.31-34
• /
• 2018

다중지능은 하워드 가드너가 제시한 개념으로, 지능이 단일한 지적 능력을 나타내는 구조(construct)이라기 보다는 다차원적인 복수의 하위 능력들로 구성된 것이라는 의미를 담고 있다. Gardner는 다중지능의 구성을 음악지능이나 신체운동지능, 논리수학지능, 언어지능, 공간지능, 인간친화지능, 자기성찰지능 그리고 자연친화지능 등과 같은 상호독립적 능력으로 분류하고 있으며, 각 개인은 각 능력 영역에서 다른 발달 수준을 가지고 있다고 본다. 본 연구는 창업자의 다중지능의 영역별 발달 특성이 창업 실행 행동, 창업 분야, 창업 성과 만족도에 영향을 미치는지를 알아보는 것을 통해 예비 창업자들이 본인의 적성과 재능에 적합한 분야에서의 창업 가능성을 탐색하도록 돕는 지도자들에게 시사점을 제공하고, 향후 창업가 육성 프로그램의 구성 개선안을 마련하는 데에 기여하고자 한다. 이를 위해 본 연구에서는 2018년 중소기업진흥공단 청년창업사관학교에 입교한 만 39세 이하의 청년창업자 200인을 대상으로 다중지능검사와 인구통계학적 특성 및 창업 특성에 대해 묻는 설문조사를 실시한 후, Pearson 상관계수 및 다변량분산분석을 통해 수집된 자료를 분석할 예정이다. 연구목적을 달성하기 위하여 설정한 가설은 다음의 3가지이다. 가설 1. 창업자의 다중지능 영역별 발달 수준과 창업 실행에는 정적인 상관이 있을 것이다. 가설 2. 창업자의 다중지능 영역별 발달 수준에 따라 창업자가 선택한 창업 분야에 유의한 차이가 있을 것이다. 가설 3. 창업자의 다중지능 영역별 발달 수준에 따라 창업자의 창업 성과 만족도에 유의미한 차이가 있을 것이다.

• Culinary science and hospitality research
• /
• v.23 no.2
• /
• pp.64-73
• /
• 2017

Although 24-hour recalls (24HR) capture detailed information on a person's food intake, this method suffers from difficulties in adequately measuring the usual intake of foods that are not consumed daily by most. Therefore, the purpose of this study is to investigate whether frequency of Food Frequency Questionnaire (FFQ) can be utilized in form of covariate when calculating usual intake of episodically-consumed foods and their distributions. Data used in this study was from the Korean National Healthy and Nutrition Examination Survey (KNHANES) 2012~2014 (3 years) and 10,945 subjects participated in this survey who performed both of 24HR and FFQ. In order to analyze the data, amount of intake in each food, which was reported in 24HR was recalculated according to 112 items in FFQ. We first assessed the relationship between FFQ frequency and the amount reported on 24HR. Second, we assessed the relationship between usual portion size of FFQ and the amount reported on 24HR. Our hypothesis was that people who reported high FFQ-reported frequency or FFQ-reported usual portion size would consume larger amounts of that food on 24HR than those with lower frequency or portion size of consumption of a food on the FFQ. For 59 of 112 individual foods (52.2%), there were statistically significant increasing relationships between FFQ frequency and consumption-day intake. Also, 102 of 112 individual foods (90.3%), there were statistically significant increasing relationships between FFQ usual portion size and consumption-day intake. For 10 of 13 food groups (grains, fruits, eggs, pulses, root and tuber crops, milk products, meat, beverage, alcoholic drink, vegetable, seaweeds and others), there were statistically significant increasing relationships between FFQ frequency and consumption-day intake. And there were statistically significant increasing relationships between FFQ usual portion size and consumption-day intake for all food groups. This study confirmed consistent correlation between reported FFQ frequency or usual portion size of food (group) consumption and consumption-day intake on 24HR. Therefore the frequency data may be utilized as important covariate when estimating usual intake of food or food groups.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.1
• /
• pp.70-77
• /
• 2015

With the purpose of studying the effects of K-wave event sponsorship on corporate image, surveys were conducted against visitors at K-wave marketing events in Tokyo and Nagoya which yielded 199 viable samples. These samples were subjected to descriptive and multivariate statistics analysis. Average and standard deviation were calculated and measured for total correlation coefficient to find out characterize of study variables. A Cronbach's alpha coefficient exceeding 0.7 indicated a good to excellent credibility of the measuring instrument. In addition, exploratory factor analysis was employed to establish validity of the measuring instrument. In order to determine the characteristics of K-wave events and the cause and relation of the subsequent effects on corporate image that stems from the aforementioned characteristics, 4 sub hypotheses were derived from 1 major hypothesis, of which 3 were determined to have a substantial and meaningful influence on the final outcome while 1 was rejected. However, due to lack of advance research, additional and continuous studies are warranted to establish a systemized theory in this field and further on, to observe such theories bear fruit in real world applications in the industry.

• Journal of the Korean Society for Library and Information Science
• /
• v.30 no.2
• /
• pp.167-188
• /
• 1996

The lack of an understanding of the characteristics and searching abilities of a specific user group in computer-based information systems in libraries hinders library and information science professionals in making the best decisions when designing, acquiring, and managing information systems. The objective of this study was to provide information on the characteristics and searching abilities of specific groups such as Korean college students & ones who study abroad, male & female, undergraduate & graduate students, etc. This study also has focused on the methods of loaming to use OPACs and non-user study. Questionnaire was administered to both Korean college students in the city of Taegu, Korea and students who study abroad in the state of Texas, US.A. 345 usable questionnaires were obtained and analyzed. These were analyzed using descriptive, inferential statistics, multiple correlation, and SPSS software. The. major findings of this study are: (1) There was a significant difference among specific student user groups except undergraduate and artiste-athlete students in the distribution of their knowledge about how to use OPACs: (2) There was a significant difference among specific groups in the means of their knowledge: (3) There was no significant difference among un. groups in the distribution of loaming method to use OPAC systems : (4) The correlation between the number of searching methods that the respondents knew in using OPACS and the amount of using computers (0.6635) is comparatively higher than my other correlation to the searching methods. Also, years of experience using computers, frequencies of computer use, and frequencies of OPAC use are comparatively higher than frequencies of library use and frequencies of manual card catalog un: (5) Frequencies of manual card catalog use have low negative correlations with the number of searching methods that the respondents knew in using OPACs: (6) Frequencies of manual card catalog use have little if any negative negative with OPAC and computer use. Conclusions are drawn from the findings in this paper, and recommendations an proposed when designing, adopting, or managing a new system. Topics fur future studies on the characteristics of OPAC systems and their use are also suggested.

• Journal of the Korean Geographical Society
• /
• v.39 no.2
• /
• pp.212-228
• /
• 2004

This paper is concerned with an important aspect of regional income convergence, ${\beta}$-convergence, which refers to the negative relationship between initial income levels and income growth rates of regions over a period of time. The common research framework on ${\beta}$-convergence which is based on OLS regression models has two drawbacks. First, it ignores spatially autocorrelated residuals. Second, it does not provide any way of exploring spatial heterogeneity across regions in terms of ${\beta}$-convergence. Given that empirical studies on ${\beta}$-convergence need to be edified by spatial data analysis, this paper aims to: (1) provide a critical review of empirical studies on ${\beta}$-convergence from a spatial perspective; (2) investigate spatio-temporal income dynamics across the U.S. labor market areas for the last 30 years (1969-1999) by fitting spatial regression models and applying bivariate ESDA techniques. The major findings are as follows. First, the hypothesis of ${\beta}$-convergence was only partially evidenced, and the trend substantively varied across sub-periods. Second, a SAR model indicated that ${\beta}$-coefficient for the entire period was not significant at the 99％ confidence level, which may lead to a conclusion that there is no statistical evidence of regional income convergence in the US over the last three decades. Third, the results from bivariate ESDA techniques and a GWR model report that there was a substantive level of spatial heterogeneity in the catch-up process, and suggested possible spatial regimes. It was also observed that the sub-periods showed a substantial level of spatio-temporal heterogeneity in ${\beta}$-convergence: the catch-up scenario in a spatial sense was least pronounced during the 1980s.