• The Korean Journal of Applied Statistics
• /
• v.34 no.1
• /
• pp.39-56
• /
• 2021

Many researches have been done on portfolio optimization since Markowitz (1952) published a diversified investment model. Markowitz's mean-variance portfolio optimization problem is established under the assumption that the distribution of returns follows a normal distribution. However, in real life, the distribution of returns does not follow a normal distribution, and variance is not a robust statistic as it is heavily influenced by outliers. To overcome these potential issues, mean-shortfall portfolio model was proposed that utilized downside risk, shortfall, as a risk index. In this paper, we propose a perturbation method that uses the shortfall as a risk index of the portfolio. The proposed portfolio utilizes an adaptive Lasso to obtain a sparse and stable asset selection because it can reduce management and transaction costs. The proposed optimization is easily applicable as it can be computed using an efficient linear programming. In our real data analysis, we show the validity of the proposed perturbation method.

• The Journal of the Korea Contents Association
• /
• v.21 no.6
• /
• pp.380-391
• /
• 2021

In this study, 116 pairs of 5-year-olds and their mothers who are attending at child care centers and kindergartens in Seoul and Incheon were selected for the study to analyze the difference in the mother's emotional expressiveness and children's ability to solve interpersonal problems. The data were analyzed by descriptive statistical analysis and independent sample t-test using SPSS 23.0 program. The results of this study are as follows: First, the negative emotionality of children was significantly different according to the gender of the child, and mothers' emotional expressiveness was significantly different according to the presence of siblings. Second, it was found that mothers of children with higher negative emotionality expressed more negative emotions than children with lower negative emotionality. Third, the children's interpersonal problem solving skills did not show any difference depending on the children's negative emotionality.

• Journal of Korean Dental Hygiene Science
• /
• v.4 no.1
• /
• pp.65-77
• /
• 2021

Background: The purpose of the present study was to evaluate changes in the communication capabilities of dental hygiene students after completing a problem based learning (PBL) dental communication curriculum. With this information, we intend to gather the basic data necessary to stress the need for and value of an education in communication regarding dental hygiene. Methods: PBL-based education was provided to a total of 49 third-year dental hygiene students who took the dental communication class taught by the Department of Dental Hygiene at S University during the 2^nd semester of 2020. The relevant self-evaluation was modified, based on the aim of the present study, to refer to three basic key competencies related to the communication capabilities of dental hygienists. An assessment of dental communication competency was conducted by analyzing the changes in self-evaluations before and after completing the course, for each question, using a paired t-test. The statistical significance level was set at p < 0.05. Results: Analysis of core competencies before and after PBL-based dental communication education indicated that all competencies were significantly improved after education (p < 0.01). Conclusion: Dental hygiene students' dental communication skills increased significantly after completing PBL-based dental communication education. Therefore, a PBL-based dental communication curriculum is effective in improving dental communication skills for dental hygiene students.

• Journal of The Korean Society of Integrative Medicine
• /
• v.8 no.4
• /
• pp.241-251
• /
• 2020

Purpose : This study examined the effect of locomotive syndrome on stress index and lifestyle patterns among elderly Koreans aged 65 years and older, and analyzed its correlation with stress index and lifestyle patterns. The purpose of this study was to provide basic data for the management and prevention of locomotive syndrome in the elderly. Methods : Using the "25-Question Geriatric Locomotive Function Scale (GLFS-25)", the study evaluated locomotive syndrome in 123 elderly Koreans aged 65 years and older. Of them, 85 patients were assigned to the locomotive syndrome group and 38 patients were assigned to the normal group. The questionnaire measured and investigated the participants' stress index and lifestyle patterns. Statistical analysis was performed using SPSS 22.0 ver. Results : Results showed the locomotive syndrome group displayed a higher stress index than the normal group, with a statistically significant difference between the two groups. The group also scored lower in the lifestyle pattern survey than the normal group did, with a statistically significant difference in high-intensity work performance ratio and average daily performance time between them. The GLFS-25 score showed a significant positive correlation with the stress index and sitting and lying down time, and a significant negative correlation with medium-intensity working time, walking, and cycling time. Conclusion : In conclusion, Locomotive syndrome in elderly Koreans is closely related to stress and lifestyle patterns, especially high-intensity work. We recommend active prevention and management of locomotive syndrome and further research into the effects of various lifestyle factors on the illness.

• The Journal of the Korea Contents Association
• /
• v.21 no.2
• /
• pp.686-698
• /
• 2021

This study was conducted to analyze the mediating effect of health status and the moderating effect of economic activity in the relationship between depression and cognitive function of the elderly. For this, the data of 2017 National survey of Older Koreans that was collected all over country by Korea Institute for Health and Social Affairs were analyzed using Structural Equation Model for statistical analysis method. The results are as follows. First, the elderly's depression was found to have a negative effect on cognitive function and health status. Second, the health status of the elderly was found to have a positive effect on cognitive function. Third, a significant mediating effect of health status was founded in the relationship between depression and cognitive function. Fourth, the moderating effect of the elderly's economic activity was found in the path through which depression affects health status and health status affects cognitive function. Based on these research results, implications of social welfare were suggested.

• International Journal of Contents
• /
• v.17 no.1
• /
• pp.37-53
• /
• 2021

With the advent of the 5G era, smart phones and communications network technology have progressed, and mobile short video of people's life can be made, Of the new tools of communication, at present, China's social short video industry has shown rapid development, and the most representative of the short video app is Douyin (international version: Tiktok). Under the background of Uses and Gratifications Theory, this study discusse the relationship between Douyin users' preference degree, use motivation, use satisfaction and attention intention. This study divides the content of Douyin video into 10 categories, selects the form of an online questionnaire survey, uses SPSS software to conduct quantitative analysis of 202 questionnaires after screening, and finally draws the following conclusions: (1) The content preference degree of Douyin short video (the high group and low group) is different in users' use motivation, users' satisfaction degree and users' attention intention. ALL results are within the range of statistical significance.(2) Douyin users' video content preference degree has a positive impact on users' use motivation, users' satisfaction degree, and users' attention intention. (3) Douyin users' motivation has a positive impact on users' satisfaction and user' attention intention. (4) Douyin users' satisfaction degree has a positive impact on users' attention intention. Based on the research results, we suggest that Douyin platform pushes videos according to users' preferences. In addition, as the preference degree has an impact on users' motivation, satisfaction degree and attention intention of using the platform, it is important that the platform's focus should to pay attention to the preference degree of users. Collecting users' preferences at the early stage of users' entering the platform is a good way to learn from, and doing a good job of big data collection and management in the later operation.

• The Korean Journal of Applied Statistics
• /
• v.33 no.6
• /
• pp.833-842
• /
• 2020

Global platforms such as Netflix, Amazon, and YouTube have developed a precise recommendation system based on various information from large set of customers and many of the items recommended here are leading to actual purchases. In this paper, a cluster analysis was conducted according to the attribute of the content, expecting that there would be a difference in user preferences according to the attribute of the recommended content. Gower distance was used for use regardless of the type of variables. In this paper, using the data of movie rating site 'The Movie Dataset', the users were grouped hierarchically and recommended movies based on genre, director and actor variables. To evaluate the recommended systems proposed, user group was divided into train set and test set to examine the precision. The results showed that proposed algorithms have far higher precision than UBCF.

• Convergence Security Journal
• /
• v.20 no.5
• /
• pp.53-63
• /
• 2020

In accordance with the revision of the Data 3 Act, such as the Personal Information Protection Act, it is possible to process pseudonym information without the consent of the information subject for statistical creation, scientific research, and preservation of public records, and unlike personal information, it is legal for personal information leakage notification and personal information destruction There are exceptions. It is necessary to revise the pseudonym information in that the standard for the pseudonym processing differs by country and the identification guidelines and anonymization are identified in the guidelines for non-identification of personal information in Korea. In this paper, we focus on the use of personal information in accordance with the 4th Industrial Revolution, examine the concept of pseudonym information for safe use of newly introduced pseudonym information, and generate / use / provide / destroy domestic and foreign non-identification measures standards and pseudonym information. At this stage, through the review of the main contents of the law or the enforcement ordinance (draft), I would like to make suggestions on future management / technical protection measures.

• Nutrition Research and Practice
• /
• v.15 no.2
• /
• pp.248-265
• /
• 2021

BACKGROUND/OBJECTIVES: This study aimed to assess the dietary behaviors of preschool children using the nutrition quotient for preschoolers (NQ-P) and analyzed the difference in the scores of the children's dietary behaviors in regards to the parents' health consciousness. SUBJECTS/METHODS: The subjects were 257 children aged 3-5 years and their parents residing in Seoul and Gyeonggi-do, South Korea. The questionnaire is composed of demographic characteristics, the NQ-P questions, and health consciousness. All data were statistically analyzed by SPSS program (ver. 25.0) and the statistical differences in variables were evaluated by χ2 test, Fisher's exact test, t-test, 1-way analysis of variance and Tukey's multiple comparison test. RESULTS: There was a significant difference on the intake frequency of processed meat by region and fast foods by age, region, and weight status (P < 0.05). There was also a significant difference in not moving around while eating by weight status and parents' effort to have healthy eating habits by sex (P < 0.05). The mean score of NQ-P of the total subjects was 59.47, which was within the medium-low grade. The mean score of balance was 61.62, and the boys were significantly higher than girls (P < 0.05). As the age of children increased, the mean score of the moderation was significantly decreased (P < 0.05). The scores of NQ-P (P < 0.05), balance (P < 0.01), and environment (P < 0.05) were significantly higher in the high group of parents' health consciousness than the low group. CONCLUSIONS: According to the results of the evaluation by NQ-P, the dietary behaviors of preschoolers residing in Seoul and Gyeonggi-do need to be improved. For improving their eating behavior and nutritional health status, parents and children need customized nutrition education programs based on sex, age, region and weight status of preschool children as well as the degree of parents' health consciousness.

• Journal of the Korean Society for information Management
• /
• v.38 no.2
• /
• pp.129-152
• /
• 2021

Regardless of previous educational attempts in youth career education, there are not specific methods for reading to improve career maturity yet. This study aims to identify the reading method based on cognitive aspect which impacts career maturity and the mediation effect of self-efficacy in this process. This study tries to understand the roles of reading by applying the various reading methods suggested in the 2015 Revised National Curriculum. Data was collected through interviews and statistical analysis from a survey completed by middle school students. Findings showed that critical reading affected the decisiveness as well as the confidence of career maturity. Also, emotional reading and creative reading influenced the preparation of career maturity. Critical reading impacted all subvariables of self-efficacy - confidence, self-regulating efficacy, and task difficulty preference. Findings also showed that emotional reading affected self-regulating efficacy. Ultimately, the confidence of self-efficacy partly mediated critical reading and decisiveness. This study contributes to guiding reading instructions for practitioners and school curriculums to develop career maturity and self-efficacy.