• 한국산업정보학회논문지
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• 제13권3호
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• pp.54-62
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• 2008

가장 일반적이고 효과적으로 사용하는 혼합된 정보은닉 기술인 스테가노그래피에서 의사소통의 존재를 숨기면서 송수신하는 자료은닉 기술과 관련된 통계적 기법을 적용하는 연구가 필요하다. 즉, 인터넷상에 존재하는 임의의 원본이미지에 비밀(은닉) 메시지가 포함된 변조된 혼합이미지를 가장 효과적으로 관리하고 찾아내는 감지 기법의 연구가 필요하다. 이 논문에서 원본이미지에 비밀자료를 숨기기 위한 스테가노그래피에 RGB, DCT 및 EWM 통계기법을 이용하여 은닉자료를 감지하고 그 위치를 찾는 기법을 확인한다. 그리고 카이스퀘어 검정법을 이용하는 기존의 방법과 비교한다.

• 통상정보연구
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• 제12권1호
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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.

• 대한간호학회지
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• 제28권3호
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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.

• 응용통계연구
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• 제19권1호
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• pp.135-148
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• 2006

독립성분분석은 차원이 높은 다변량데이타로부터 기저구조를 형성하는 독립성분을 분리하는데 사용되는 기법으로서 패턴인식, 예측 등 2차적 분석을 위한 1차 분석단계에서 사용할 수 있다. 본 연구에서는 독립성분분석을 이용하여 여러 혼합물 데이터로부터 독립성분을 분리한 다음 각 구성성분의 혼합비율을 예측하는 절차를 제안한다. 적용예로서 도금강판의 엑스선 회절강도값으로부터 여러가지 상을 분리한 다음 비음최소자승법을 이용하여 각 상의 분율을 예측하였으며, 이러한 제안방안의 타당성 평가를 위하여 모의 실험을 실시하였다.

• 응용통계연구
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• 제18권2호
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• pp.381-393
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• 2005

회귀모형에서 필요한 설명변수들의 선형결합들을 탐색하기 위한 방법 중의 하나로 분할역회귀모형을 들 수 있다. 이러한 분할역회귀모형에서 모형에 필요한 설명변수들의 선형결합의 수, 즉 차원을 결정하기 위한 여러 가지의 검정법들이 소개 되었으나 설명변수들의 정규성 가정을 필요로 하거나 다른 제약이 있다. 본 논문에서는 주성분분석에 대한 확률모형을 이 용하여 정규성가정을 필요로하지 않으며 분할의 수에 로버스트한 검정법을 소개하고 모의실험과 실제자료에 대한 적용결과를 통하여 기존의 검정법과 비교하였다.

• Communications for Statistical Applications and Methods
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• 제24권6호
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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.

• 대한간호학회지
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• 제39권3호
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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.

• 성인간호학회지
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• 제23권4호
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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.

• 보건의료산업학회지
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• 제8권4호
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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.

• 대한가정학회지
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• 제41권12호
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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.