• Journal of Intelligence and Information Systems
• /
• v.21 no.1
• /
• pp.119-142
• /
• 2015

With the explosive growth in the volume of information, Internet users are experiencing considerable difficulties in obtaining necessary information online. Against this backdrop, ever-greater importance is being placed on a recommender system that provides information catered to user preferences and tastes in an attempt to address issues associated with information overload. To this end, a number of techniques have been proposed, including content-based filtering (CBF), demographic filtering (DF) and collaborative filtering (CF). Among them, CBF and DF require external information and thus cannot be applied to a variety of domains. CF, on the other hand, is widely used since it is relatively free from the domain constraint. The CF technique is broadly classified into memory-based CF, model-based CF and hybrid CF. Model-based CF addresses the drawbacks of CF by considering the Bayesian model, clustering model or dependency network model. This filtering technique not only improves the sparsity and scalability issues but also boosts predictive performance. However, it involves expensive model-building and results in a tradeoff between performance and scalability. Such tradeoff is attributed to reduced coverage, which is a type of sparsity issues. In addition, expensive model-building may lead to performance instability since changes in the domain environment cannot be immediately incorporated into the model due to high costs involved. Cumulative changes in the domain environment that have failed to be reflected eventually undermine system performance. This study incorporates the Markov model of transition probabilities and the concept of fuzzy clustering with CBCF to propose predictive clustering-based CF (PCCF) that solves the issues of reduced coverage and of unstable performance. The method improves performance instability by tracking the changes in user preferences and bridging the gap between the static model and dynamic users. Furthermore, the issue of reduced coverage also improves by expanding the coverage based on transition probabilities and clustering probabilities. The proposed method consists of four processes. First, user preferences are normalized in preference clustering. Second, changes in user preferences are detected from review score entries during preference transition detection. Third, user propensities are normalized using patterns of changes (propensities) in user preferences in propensity clustering. Lastly, the preference prediction model is developed to predict user preferences for items during preference prediction. The proposed method has been validated by testing the robustness of performance instability and scalability-performance tradeoff. The initial test compared and analyzed the performance of individual recommender systems each enabled by IBCF, CBCF, ICFEC and PCCF under an environment where data sparsity had been minimized. The following test adjusted the optimal number of clusters in CBCF, ICFEC and PCCF for a comparative analysis of subsequent changes in the system performance. The test results revealed that the suggested method produced insignificant improvement in performance in comparison with the existing techniques. In addition, it failed to achieve significant improvement in the standard deviation that indicates the degree of data fluctuation. Notwithstanding, it resulted in marked improvement over the existing techniques in terms of range that indicates the level of performance fluctuation. The level of performance fluctuation before and after the model generation improved by 51.31% in the initial test. Then in the following test, there has been 36.05% improvement in the level of performance fluctuation driven by the changes in the number of clusters. This signifies that the proposed method, despite the slight performance improvement, clearly offers better performance stability compared to the existing techniques. Further research on this study will be directed toward enhancing the recommendation performance that failed to demonstrate significant improvement over the existing techniques. The future research will consider the introduction of a high-dimensional parameter-free clustering algorithm or deep learning-based model in order to improve performance in recommendations.

• Korean Journal of Psychosomatic Medicine
• /
• v.23 no.1
• /
• pp.47-56
• /
• 2015

Objectives:The aim of this study is to investigate any differences between non-medical and medical college students for : 1) a level and the nature of perceived stress, 2) a level of life satisfaction, and 3) the related factors affecting to life satisfaction. Methods:We measured self-reported questionnaires of stress, satisfaction with life, health behavior including happiness, alcohol use, nicotine dependency and depressive symptoms in 1,714(863 non-medical and 851 medical) college students. Results:Non-medical college students had significantly higher total stress scores than medical college students(${\chi}^2$=7.66, p<.001). In non-medical college students, employment problem score was significantly higher than medical college students(t=4.07, p<.001). In medical college students, the scores of academic achievement (t=-3.81, p<.001), change of social life(t=-2.03, p<.05), death(t=-2.05, p<.05) or sickness(t=-2.60, p<.05) of friends were significantly higher than non-medical college students. And non-medical college students showed significantly lower life satisfaction scores than medical college students(${\chi}^2$=-19.05, p<.001). We also found that life satisfaction were significantly related to happiness in non-medical college students(${\beta}$=.410, $R^2$=.325, p<.001) and depressive symptoms in medical college students(${\beta}$=-.435, $R^2$=.326, p<.001) by stepwise multiple regression analysis. Conclusions:In this study, a level and the nature of perceived stress, a level of life satisfaction, and the related factors affecting to life satisfaction showed definitely differences between non-medical and medical college students. We suggest with our findings that specified mental health promotion program need for the college student's mental health management.

• KIPS Transactions on Software and Data Engineering
• /
• v.9 no.12
• /
• pp.431-438
• /
• 2020

In this paper, the method to extract lip contour by multiple threshold is proposed. Spyridonos et. el. proposed a method to extract lip contour. First step is get Q image from transform of RGB into YIQ. Second step is to find lip corner points by change point detection and split Q image into upper and lower part by corner points. The candidate lip contour can be obtained by apply threshold to Q image. From the candidate contour, feature variance is calculated and the contour with maximum variance is adopted as final contour. The feature variance 'D' is based on the absolute difference near the contour points. The conventional method has 3 problems. The first one is related to lip corner point. Calculation of variance depends on much skin pixels and therefore the accuracy decreases and have effect on the split for Q image. Second, there is no analysis for color systems except YIQ. YIQ is a good however, other color systems such as HVS, CIELUV, YCrCb would be considered. Final problem is related to selection of optimal contour. In selection process, they used maximum of average feature variance for the pixels near the contour points. The maximum of variance causes reduction of extracted contour compared to ground contours. To solve the first problem, the proposed method excludes some of skin pixels and got 30% performance increase. For the second problem, HSV, CIELUV, YCrCb coordinate systems are tested and found there is no relation between the conventional method and dependency to color systems. For the final problem, maximum of total sum for the feature variance is adopted rather than the maximum of average feature variance and got 46% performance increase. By combine all the solutions, the proposed method gives 2 times in accuracy and stability than conventional method.

• 한국노년학
• /
• v.31 no.3
• /
• pp.831-848
• /
• 2011

The purpose of this study is to analyse the family caregivers' stress pathways by types of long term care services for the elderly, and then to discuss the findings of analysis. For this research, primary caregivers that provide care the elderly requiring long term care services sanctioned by National Health Insurance Corporation were drawn and surveyed. Among collected data, data for 258 primary caregivers by type of long term care services were used for this study. The results of this study can be summarized as follows. First, on average, the elders that utilize care service in institutions for the elderly were higher proportion of women, older, higher rate of bereavement, more children than the elders that utilize in-home care service, but some cases were vice-versa. Second, the elders that utilize care service in institutions more ADL dependency, higher proportion of severe dementia or severe stroke, higher care rank by National Health Insurance Corporation than the elders that utilize in-home care service on average. Third, primary caregivers with elders that utilize in-home care service were higher proportion of women, older, lower education level, higher rate of spouse and daughter-in-law in relationship with care recipient, less health, lower income than primary caregivers with elders that utilize care service in institutions. Fourth, subjective indicators representing caregivers' reactions to caregiving for the elderly significantly impact on caregivers' stress(ie, depression), and pathway of caregivers' stress are differentiated by type of long term care services. Fifth, stressors that have direct impacts on depression as caregiving family are differentiated by type of long term care services. Therefore, policies or programs to reduce negative mental health or stress of caregivig families should be designed differently by reflecting pathway of various stressors and stress by use types of long term care services for the elderly.

• 한국노년학
• /
• v.30 no.4
• /
• pp.1359-1375
• /
• 2010

Expecting the expansion of the elderly population under long-term home care with the coming of the aged society, this study purposed to propose a prevention and self-reliance support model and to get practical implications for minimizing dependency on care benefits and enhancing the effectiveness of prevention and self-reliance support. Research methods employed for this study were: first, reviewing theoretical literature for clarifying the concept of prevention and self-reliance support in providing long-term care benefits for the elderly; second, identifying factors hindering prevention and self-reliance support through analyzing standard long-term care use plans and documents related to long-term care benefits at elderly welfare centers to which the research subjects belonged; and third, surveying care benefit users on factors hindering their use of prevention and self-reliance support and their needs in the use of care benefits. Based on the results of the three types of qualitative research, we proposed directions for prevention and self-reliance support modeling and suggested practical implications for enhancing the effectiveness of prevention and self-reliance support. For this study, we collected documentary materials and conducted in-depth interviews with the participants with the consents and cooperation of managers and professional social workers at day care centers and elderly welfare centers in D City. According to the results of this study, literature review suggested that long-term care prevention and self-reliance support should be provided in a way of 'strengthening user-centered support systems,' which support elderly long-term care beneficiaries' right to lead a life as the subject of their own life. Document analysis found the absence of benefits related to health and medicine and lack of social support systems for prevention and self-reliance support, and the results of in-depth interviews suggested the necessity to strengthen services related to elderly long-term care beneficiaries' prevention and self-reliance, and the keen needs of the long-term care elders for prevention and self-reliance included: ① loneliness, anxiety, fear; ② missing for and worry about children and people; ③ moving, outing; ④ health and medical services, rehabilitation programs; ⑤ desire to use day care; ⑥ inconvenience of house structure; ⑦desire for meal menus; and ⑧ the occurrence of disuse syndrome. Based on these results, we suggested the base of prevention and self-reliance support modeling with three axes: ① strengthening user-centered support systems; ② strengthening support systems connected to health and medicine; and ③ strengthening social support systems.

• 한국노년학
• /
• v.29 no.4
• /
• pp.1559-1575
• /
• 2009

As the basic old-age pension system was enforced in 2008, the base for old-age income security was founded. However, due to the basic old-age pension played a minor role as assistant allowance, it did not reach to sufficient level to cover full income security system. It is estimated that the dependency on private transfer income among the elderly who are difficult to be economically independent is still high. Therefore the poverty rate of the elderly households, who are not economically active or who are not protected by old-age income security system, is more likely to be higher than that of non-elderly households. Based on the assumption that public transfer income system should become a central means of old-age life guarantee, this study examined the poverty mitigation effects among the elderly households by comparing the private transfer income and the public transfer income. For this purpose, we selected single-elderly-households who have been considered the most vulnerable to poverty. We used 2006- 2008 Household Income and Expenditure Survey dataset that contained single-elderly who were older than 65 years old. To understand the conditions of poverty among single-elderly-households and the degree of poverty-reducing effect originated from income transfer system, we compared the poverty rates of total households and the whole elderly households. Next, we analysed the poverty of the single-elderly-households by social demographic factors such as gender, age, and economic activity. Our major findings are as follows: First, the poverty rate of the whole elderly households were not reduced, even though the basic old-age pension and long-term care management system were enforced in 2008. Second, half of the elderly households including single-elderly-households belonged to the absolute poverty line. Relatively higher level of poverty among the single-elderly-households was found especially those who were female, unemployed, low-educated, older, and rural single-elderly-households. Third, the effect of the public transfer income on mitigating the single-elderly-households poverty showed a little progress. However, even greater poverty reducing effect was found by the private transfer income system. Fourth, in a group of the public transfer systems, the public assistance such as supporting living costs contributed more to reduce poverty of the elderly population than the public pension system did.