• Journal of Internet Computing and Services
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• v.25 no.2
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• pp.39-47
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• 2024

Time series analysis is widely employed by many organizations to solve business problems, as it extracts various information and insights from chronologically ordered data. Among its applications, measuring time series similarity is a step to identify time series with similar patterns, which is very important in time series analysis applications such as time series search and clustering. In this study, we propose an efficient method for measuring time series similarity that focuses on anomalies rather than the entire series. In this regard, we validate the proposed method by measuring and analyzing the rank correlation between the similarity measure for the set of subsets extracted by anomaly detection and the similarity measure for the whole time series. Experimental results, especially with stock time series data and an anomaly proportion of 10%, demonstrate a Spearman's rank correlation coefficient of up to 0.9. In conclusion, the proposed method can significantly reduce computation cost of measuring time series similarity, while providing reliable time series search and clustering results.

• Information Systems Review
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• v.21 no.2
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• pp.69-89
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• 2019

Recently, consumers are increasingly interested in the sharing economy, which utilizes various resources by sharing unused or under-used products/services with others. This study focuses on Airbnb, a representative sharing economy platform, to identify the success factors of the sharing accommodation services. The key properties of sharing accommodation services are extensively surveyed from extant literature and are classified them into the three important factors (economic, convenience, and trust) that influence the success of room-sharing services. The research data include 1,673 Airbnb hosts who offered accommodations in New York City, USA, in June 2018. The research variables of economic-, convenience-, and trust-related factors are utilized in the empirical analyses. The results of this study show that the number of available facilities, flexibility of refunds, the response rate and time to customer requests, and the status of Super host are positively associated with guest satisfaction from sharing accommodation services. This study bears significant managerial implications by suggesting a set of practical guidelines to participants in sharing accommodation services.

• The Journal of Engineering Geology
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• v.34 no.1
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• pp.51-65
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• 2024

Landslides are natural disasters that causes significant property damage worldwide every year. In Korea, damage due to landslides is increasing owing to the effects of climate change, and it is important to identify the factors that increase the prevalence of landslides in order to reduce the damage they cause. Therefore, this study used a random forest model to analyze the importance of 14 factors in influencing landslide damage in a specific area of Chungju, Chungcheongbuk-do province, Korea. The random forest model performed accurately with an AUC of 0.87 and the most-important factors were ranked in the order of aspect, slope, distance to valley, and elevation, suggesting that topographic factors such as aspect and slope more greatly influence landslide damage than geological or soil factors such as rock type and soil thickness. The results of this study are expected to provide a basis for mapping and predicting landslide damage, and for research focused on reducing landslide damage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.71-83
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• 2008

In this paper, the basic principle, the application and the limitation of Infrared thermography technique to detect defects in different kinds of concrete structures are reviewed. Considered are voids beneath the concrete surface with experiments, delamination between concrete surface and fiber reinforced polymer sheet, the deterioration of steel bars in reinforced concrete, surface defects in historical buildings, pavements, bridges, and railway track graves. As a result, we conclude that infrared thermography methods are useful for fast detecting defects; however, they are influenced by environmental factors, specially temperature. Therefore it is recommended to use the infrared thermography technique with other NDT equipments to expect better result.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.164-172
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• 2008

The heat of hydration for early aged mass concrete induces high temperature with the hydration. Control of the temperature difference across a section is an effective strategy to minimize the hydration heat induced cracks for the structures where internal restraint is dominant. The current prevention methods for hydration cracking show some limitations for the control of thermal gradients, and these limitations could make micro and macro cracks in surface and core of concrete. Especially cooling methods can decrease the increasing hydration temperature, but it can not prevent the problem while decreasing temperature. Consequently heating pipes are added simultaneously with the cooling pipes in order to control the temperature gradients between core and surface of the concrete, followed by the finite element analysis (FEA). Based on the FEA, the proposed method using cooling pipe and heating pipes together has been found to be an effective alternative in thermal gradient control, in terms of controlling temperature induced cracks significantly.

• Journal of the Korean Chemical Society
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• v.68 no.4
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• pp.185-190
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• 2024

Recently, it was reported that the benzobisoxazole (BBO) molecule can be used for independent modulation of the HOMO and LUMO energy levels. In this study, we utilized this interesting property of BBO to quantitatively investigate the substituent effects according the substituents. We designed and proposed four BBO model systems (1BBO, 2BBO, 3BBO and 4BBO) by extending the π-conjugation lengths based on a BBO molecule. Two directions of substitution (x-axis and y-axis) and 15 various substituents were considered. From strong correlation between the LUMO energy levels of x-axis substitution and HOMO energy levels of y-axis substitution calculated from DFT method, it is found that the standardization of substitution effects can be established from BBO model systems. In addition, we demonstrated that the HOMO values of y-axis substituted 3BBO show the best performance to define the order of substituent effects. Our proposed way can be used to expect the substituent effect of any arbitrary substituents and develop the organic sensors and organic light emitting diodes.

• Industry Promotion Research
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• v.9 no.3
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• pp.175-183
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• 2024

The purpose of this study is to derive a UX that can help the use of fintech applications by senior users in their 60s or older, which has naturally increased with the increase in the elderly population. The study extracted five factors commonly considered important in fintech applications and was conducted based on a survey of general users and in-depth interviews with senior users. The research factors were extracted through a literature review into three general user experience research factors and two senior user experience research factors. After a survey targeting general users, in-depth interviews were conducted with senior users. As a result, we found notable differences in concerns about responsiveness and perceived usefulness between general and senior users. Based on the characteristics derived from the results of this study, we designed UX to help senior users use fintech applications.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.23 no.4
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• pp.1-15
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• 2024

The COVID-19 pandemic significantly impacted societies, particularly the elderly with higher susceptibility and mobility constraints. This study investigates COVID-19's influence on elderly travel at subway stations using card data. Analyzing pre/post-COVID-19 data via multilinear regression, we found factors like subway transfer lines, presence of rivers, the area of traditional markets, number of traditional Korean medicine clinics, number of cultural facilities, and number of large commercial facilities correlated positively with elderly travel. Post-COVID-19, effects of variables related to public transportation and employment, and indoor leisure facilities decreased, while the effects of outdoor and traditional culture-related facilities increased. These findings indicate significant pandemic-induced alterations in the mobility patterns of senior citizens in Seoul, highlighting shifts towards safer, more accessible environments.

• 21st centry Political Science Review
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• v.28 no.2
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• pp.189-209
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• 2018

This study is about Taiwanese Official Development Assistance. This study explains the history, the institution, the policies and several major determinants which affect distribution of Taiwanese ODA. Taiwanese ODA shows several features. State survival, recognition from the international society and competition with China have been main goals of Taiwanese ODA. In addition, the Taiwanese government has tried to promote economic interests in both trade and investment by giving ODAs and by linking them with foreign economic policies. Taiwanese ODA policy has gradually changed from political conerns to more acceptance of international ODA norms and institutions. Especially in the period of MDGs and SDGs, the Taiwanese government has tried to comply with existing and newly developing international ODA norms. This study shows on 'exceptional' case of non OECD-DAC member country's ODA policies. In the future, more studies which compare similarities and differences of OECD DAC members' and non-members' ODA policies will be needed. Based upon more studies, we may find general goals and policies pursued by donor countries.

• Journal of School Social Work
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• v.42
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• pp.163-185
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• 2018

The purpose of this study is to examine the mediating effects of fandom activities on the path between depression and career-identity of adolescents. For the purpose, the study analyzes the longitudinal data of 941 adolescents from the 4th through 6th waves accumulated by the panel study of the Korea Children and Youth Panel Survey(KCYPS) of the Korean National Youth Policy Institute. For analytic methods, we use structural equation modeling, and the bootstrapping method. The results of the structural equation modeling analysis show that depression of adolescents has a direct negative influence on their career-identity. In addition, depression also has a direct positive association with on fandom activities influence. Lastly, the study results reveal that adolescents' fandom activities have a significant mediating effect on the relationship between depression and career-identity. In other words, depression itself has a negative effect on youth career identity, but increases the level of youth fandom activities, and the increased fandom activities can affect career identity positively. In conclusion, the study discusses practical and political implications regarding the positive function of youth fandom activities for their developmental outcomes.