• Journal of Korea Society of Industrial Information Systems
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• v.13 no.3
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• pp.54-62
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• 2008

For a message hiding technique to be effectual, it needs to have availability, confidentiality and integrity. Steganography is the science of hiding one message within other types of digital contents. In this case, attempt to defeat steganalysis by restoring the statistics of the composite image to resemble that of the cover, these discrepancies expose the fact that hidden communication is happening. In this paper, I present a steganography scheme capable of concealing a piece of secrete information in a host image and base on the technique's OCT, RGB, statistical restoration.

• International Commerce and Information Review
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• v.12 no.1
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• pp.99-121
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• 2010

This paper reviews the categories and properties of risk measures, analyzes the classes and structural equations of volatility forecasting models, and presents the practical methodologies and their expansion methods of estimating and forecasting the volatilities of exchange rates using Excel spreadsheet modeling. We apply the GARCH(1,1) model to the Korean won(KRW) denominated daily and monthly exchange rates of USD, JPY, EUR, GBP, CAD and CNY during the periods from January 4, 1998 to December 31, 2009, make the estimates of long-run variances in the returns of exchange rate calculated as the step-by-step change rate, and test the adequacy of estimated GARCH(1,1) model using the Box-Pierce-Ljung statistics Q and chi-square test-statistics. We demonstrate the adequacy of GARCH(1,1) model in estimating and forecasting the volatility of exchange rates in the monthly series except the semi-variance GARCH(1,1) applied to KRW/JPY100 rate. But we reject the adequacy of GARCH(1,1) model in estimating and forecasting the volatility of exchange rates in the daily series because of the very high Box-Pierce-Ljung statistics in the respective time lags resulting to the self-autocorrelation. In conclusion, the GARCH(1,1) model provides for the easy and helpful tools to forecast the exchange rate volatilities and may become the powerful methodology to overcome the application difficulties with the spreadsheet modeling.

• Journal of Korean Academy of Nursing
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• v.28 no.3
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• pp.718-728
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• 1998

Breast self-examination is the most effective and easiest way for women to increase the responsible consciousness about their health. The purpose of this study was to test the variables impacted to promote breast self-examination practice. The research design used in this study was a nonequevalent control group of a non-synchronized design. The sample that was assembled consisted of 124 women. A purposive sample consisted of 124 women. Each subject was given to assessed on the following the demographic data related to the breast self-examination, knowledge of self-examination, accuracy, in performing self-examination, self-efficacy about breast cancer and breast self-examination, and the number of subjects who found a mass. The result of this study may be summarized as follows : 1. To examine the theretical model fit to the data, chi square test statistics and goodness of fit index were identified($\chi$$^2$=2.30, df=2, GFI=0.99, AGFI=0.94 RMSR=0.02, NFI=0.99, NNFI=0.99, Critical Number=439). 2. The direct effects of education of breast self-examination were knowledge, self-efficacy, accuracy, number finding a mass. But the Indirect effect of education on breast self-examination was frequency of breast self-examination. 3. Knowlege, as direct paths to the breast self-examination practices, was removed in the theoretical model. The parsimonious best fit model included self-efficacy, accuracy, the number finding mass, frequency of breast self-examination practices. 4. The final model produced a chi-square=5.58(p=0.35) with df=5, and GFI =0.99, AGFI =0.94, RMSR=0.03, NFI=0.99, NNFI=0.99, CN=339 indicating very a good fit. Based on the result of this study, education of breast self-examination is very effective for increasing the competency of the breast self-examination through the knowledge and self-efficacy. Resources to promote self-efficacy may be helpful to increase the frequency of self-examination because self-efficacy is a direct effect on it. These findings suggest the need to develop nursing strategy to promote the self-efficacy of breast self-examination.

• The Korean Journal of Applied Statistics
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• v.19 no.1
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• pp.135-148
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• 2006

Independent component analysis (ICA) is a statistical method for transforming an observed high-dimensional multivariate data into statistically independent components. ICA has been applied increasingly in wide fields of spectrum application since ICA is able to extract unknown components of a mixture from spectra. We focus on application of ICA for separating independent sources and predicting each composition using extracted components. The theory of ICA is introduced and an application to a metal surface spectra data will be described, where subsequent analysis using non-negative least square method is performed to predict composition ratio of each sample. Furthermore, some simulation experiments are performed to demonstrate the performance of the proposed approach.

• The Korean Journal of Applied Statistics
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• v.18 no.2
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• pp.381-393
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• 2005

As a promising technique for dimension reduction in regression analysis, Sliced Inverse Regression (SIR) and an associated chi-square test for dimensionality were introduced by Li (1991). However, Li's test needs assumption of Normality for predictors and found to be heavily dependent on the number of slices. We will provide a unified asymptotic test for determining the dimensionality of the SIR model which is based on the probabilistic principal component analysis and free of normality assumption on predictors. Illustrative results with simulated and real examples will also be provided.

• Communications for Statistical Applications and Methods
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• v.24 no.6
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• pp.663-671
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• 2017

Some genetic association tests include an unidentifiable nuisance parameter under the null hypothesis of no association. When the mode of inheritance (MOI) is not specified in a case-control design, the Cochran-Armitage (CA) trend test contains an unidentifiable nuisance parameter. The transmission disequilibrium test (TDT) in a family-based association study that includes the unaffected also contains an unidentifiable nuisance parameter. The hypothesis tests that include an unidentifiable nuisance parameter are typically performed by taking a supremum of the CA tests or TDT over reasonable values of the parameter. The p-values of the supremum test statistics cannot be obtained by a normal or chi-square distribution. A common method is to use a Davies's upper bound of the p-value instead of an exact asymptotic p-value. In this paper, we provide a unified sine-cosine process expression of the CA trend test that does not specify the MOI and the TDT that includes the unaffected. We also present a closed form expression of the exact asymptotic formulas to calculate the p-values of the supremum tests when the score function can be written as a linear form in an unidentifiable parameter. We illustrate how to use the derived formulas using a pharmacogenetics case-control dataset and an attention deficit hyperactivity disorder family-based example.

• Journal of Korean Academy of Nursing
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• v.39 no.3
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• pp.446-457
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• 2009

Purpose: The aim of this study was to construct a structural equation model that would further explain the continuously increasing substance use disorder in Korean adolescents. Methods: Survey visits using a structured questionnaire were conducted with 3,885 students in 2 middle schools and 2 high schools in Busan. A total of 13 instruments were used in this model. The analysis of data was done with both SPSS 14.0 for descriptive statistics and AMOS 5.0 for covariance structure analysis. Results: Based on the constructed model, belief on substance use was found to have a significantly direct effect in influencing adolescent substance use. In addition, other factors such as family environment, satisfaction with school life, self-concept, social support, and personality vulnerability indirectly affected substance use. The final modified model yielded Chi-square=2,987(p<.001), df=121, ${\chi}^2$/df=22.1, GFI=.96, AGFI=.93, NFI=.91, PNFI=.72, PGFI=.72, RMSEA=.07 and exhibited fit indices. Conclusion: This study constructed a model that addresses the factors related to adolescent substance use and explains the relationship of these factors in influencing substance use among Korean adolescents. Findings from this study can contribute to designing appropriate prevention strategies to reduce substance related disorders in adolescents.

• Korean Journal of Adult Nursing
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• v.23 no.4
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• pp.386-396
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• 2011

Purpose: This study was conducted to examine the level of physical activities at time points of pre-illness and current treatment, and the differences in body mass index (BMI), anxiety, depression and fatigue according to their physical activity in cancer patients undergoing chemotherapy. Methods: The survey was used with 126 cancer patients undergoing daily chemotherapy at injection room, cancer clinic of C University Hospital in G city. Data were collected from June to September, 2009 using a structured questionnaire. The data were analyzed by descriptive statistics, chi-square, Fisher's exact test and t-test using SPSS/WIN15.0. Results: The significant increase in physical activity was reported from pre-illness to the time in treatment (${\chi}^2$=69.027, p<.001). The anxiety level of the group with increased physical activity was significantly lower than those who did not (t=-2.218, p =.028). There were no significant differences in BMI, depression, and fatigue according to physical activity. Conclusion: The level of physical activity was significantly associated with the anxiety level of the cancer patients undergoing chemotherapy. Cancer patients should been encouraged regular physical activity during chemotherapy treatment. And an appropriative nursing intervention should be established in order to motivate cancer patients to increase physical activity.

• The Korean Journal of Health Service Management
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• v.8 no.4
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• pp.81-94
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• 2014

The purpose of this study is to investigate factors affecting cancer mortality inequality in Busan according to demographic characteristics identified based on the region's mortality data including cancer incidence and mortality rates, ultimately helping the region improve its existing health policies and establish a more effective cancer prevention policy. To achieve this purpose, this researcher surveyed data about all persons who died in Busan from 2006 to 2009. Data were analyzed with an SPSS 18.0 program using descriptive statistics, Chi-Square(${\chi}^2$), and Logistic Regression analysis. Findings of the study can be summarized as follows. First, in Busan, men were about two times higher in cancer mortality rate than women. Second, persons who died of cancer in Busan were significantly different from one another in terms of demographic characteristics, especially, age, marital status, and job. Third, factors affecting cancer mortality inequality in Busan included such demographic characteristics as gender, age at the time of death, marital status, educational background, and job.

• Journal of the Korean Home Economics Association
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• v.41 no.12
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• pp.13-26
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• 2003

This study was designed (1) to examine adolescents' body cathexis, ideal body image, clothing behavior, and clothing purchasing behavior, and (2) to identify gender and age differences. Descriptive statistics, Chi-Square ($\chi^2$) analysis, Analysis of Variance (ANOVA), and Duncan-Test were employed to analyze the data collected from the convenience sample of 729 middle- and high-school students in Gyeongnam, Korea. Adolescents tended to be dissatisfied with their body, while female high school students' dissatisfactory degrees were higher The ideal body image was thinner than normal, and neither gender nor age differences were observed. Adolescents showed higher dependences compared to other clothing behaviors including conformity, fashion, popularity, brand, and exhibition, and gender and age differences were observed. Fit/comfort and clothing displayed in store were most important evaluative criterion and information search method. Adolescents tended to prefer shopping in department store with friends or parents in less than 3 hours. Gender and age differences were observed in those clothing purchasing behavior. Marketing strategies generated from the results of this study were suggested.