• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.3
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• pp.147-155
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• 2022

The accumulated ice and snow during the operation of aircraft and railway vehicles can degrade aerodynamic performance or damage the major components of vehicles. Therefore, it is crucial to predict the temporal growth of ice for operational safety. Numerical simulation of ice is widely used owing to the fact that it is economically cheaper and free from similarity problems compared to experimental methods. However, numerical simulation of ice generally divides the analysis into multi-step and assumes the quasi-steady assumption that considers every time step as steady state. Although this method enables efficient analysis, it has a disadvantage in that it cannot track continuous ice evolution. The purpose of this study is to construct a surrogate model that can predict the temporal evolution of ice shape using reduced-order modeling. Reduced-order modeling technique was validated for various ice shape generated under 100 different icing conditions, and the effect of the number of training data and the icing conditions on the prediction error of model was analyzed.

• Journal of Digital Convergence
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• v.20 no.2
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• pp.217-223
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• 2022

Subspace clustering for online data streams requires a large amount of memory resources as all subsets of data dimensions must be examined. In order to track the continuous change of clusters for a data stream in a finite memory space, in this paper, we propose a grid-based subspace clustering algorithm that effectively uses memory resources. Given an n-dimensional data stream, the distribution information of data items in data space is monitored by a grid-cell list. When the frequency of data items in the grid-cell list of the first level is high and it becomes a unit grid-cell, the grid-cell list of the next level is created as a child node in order to find clusters of all possible subspaces from the grid-cell. In this way, a maximum n-level grid-cell subspace tree is constructed, and a k-dimensional subspace cluster can be found at the k^th level of the subspace grid-cell tree. Through experiments, it was confirmed that the proposed method uses computing resources more efficiently by expanding only the dense space while maintaining the same accuracy as the existing method.

• Korean Association of Arts Management
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• no.56
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• pp.217-242
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• 2020

At a moment in which the entire culture and arts field is in crisis due to the Covid-19 pandemic, the audience development strategies practiced by arts organizations require significant adaptation. In this paper we consider the theater for young audiences, Youngji, produced by the TYA(Theater for Young Audiences) Research Center(TYARC) of the National Theater Company of Korea (NTCK). We examine how an arts organization develops youth audiences and creates a participatory culture when normal non-face-to-face engagement is not possible. We applied an Action Research methodology to our research filed, which allowed us to track continuous change based on the evolving practices and contingencies of one arts sector organization. Using Brown and Novak-Leonard's (2011) audience involvement spectrum, Koste's (1995) concept of creative drama, and Moore's (1993) transactional distance theory, we explored the possibility of active audience development by analyzing the ways in which NTCK's arts education has adapted its approach to audience development. We find that, even in this non-face-to-face era, it is possible to effectively develop youth audiences through a dramatic play that continues from play to drama.

• Korean Journal of Construction Engineering and Management
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• v.23 no.6
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• pp.54-64
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• 2022

The continuous aging of the domestic construction industry and the shortage of human resource are no longer a problem for the future, but must be solved for the survival of the domestic construction industry, given the characteristics of the labor-intensive construction industry and the continuing negative image of young people toward the construction industry. It is undoubtedly a prerequisite. This study is aimed to tackle the fundamental problem of the construction labor shortage faced by the domestic construction industry by comparing and analyzing the case of MMC technology development in the UK, which has been preparing fast-track response measures for the past 5 years to solve the labor shortage problem, and the case of Buildability technology development in Singapore, which is seeking mid- to long-term countermeasures for about 20 years. Also, This research provides the initial research & development roadmap for Korean Countermeasures Strategy.

• International Journal of Computer Science & Network Security
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• v.22 no.11
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• pp.11-18
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• 2022

Linking Ukraine's education system with the trends of global digitalization is mandatory to ensure the sustainable, long-term development of the country, as well as to increase the sustainability of the education system and the economy as a whole during the crisis period. Now the main problems of the education system in Ukraine are manifested in a complex context caused by Russian armed aggression. In the context of war, problems include differences in adaptation to online learning among educational institutions, limited access to education for vulnerable groups in the zone of active hostilities, the lack of digital educational resources suitable for online learning, and the lack of basic digital skills and competencies among students and teachers necessary to properly conduct online classes. Some of the problems of online learning were solved in the pandemic, but in the context of war Ukrainian society needs a new vision of education and continuous efforts of all social structures in the public and private environment. In the context of war, concerted action is needed to keep education on track and restore it in active zones, adapting to the needs of a dynamic society and an increasingly digitized economy. Among the urgent needs of the education system are a change in the teaching-learning paradigm, which is based on content presentation, memorization, and reproduction, and the adoption of a new, hybrid educational model that will encourage the development of necessary skills and abilities for students and learners in a digitized society and enable citizens close to war zones to learn.

• Informatization Policy
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• v.30 no.2
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• pp.22-45
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• 2023

In research on the use of AI-based voice assistant services, problems related to the user's trust and privacy protection arising from the experience of service use are constantly being raised. The purpose of this study was to investigate empirically the effects of individual trust in AI and online privacy concerns on the continued use of AI-based voice assistants, specifically the impact of their interaction. In this study, question items were constructed based on previous studies, with an online survey conducted among 405 respondents. The effect of the user's trust in AI and privacy concerns on the adoption and continuous use intention of AI-based voice assistant services was analyzed using the Heckman selection model. As the main findings of the study, first, AI-based voice assistant service usage behavior was positively influenced by factors that promote technology acceptance, such as perceived usefulness, perceived ease of use, and social influence. Second, trust in AI had no statistically significant effect on AI-based voice assistant service usage behavior but had a positive effect on continuous use intention. Third, the privacy concern level was confirmed to have the effect of suppressing continuous use intention through interaction with trust in AI. These research results suggest the need to strengthen user experience through user opinion collection and action to improve trust in technology and alleviate users' concerns about privacy as governance for realizing digital government. When introducing artificial intelligence-based policy services, it is necessary to disclose transparently the scope of application of artificial intelligence technology through a public deliberation process, and the development of a system that can track and evaluate privacy issues ex-post and an algorithm that considers privacy protection is required.

• Korean Journal of Heritage: History & Science
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• v.52 no.3
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• pp.74-93
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• 2019

The Bird Track Site in the Haman Formation in Yongsanri (Natural Monument No. 222) was reported on the named Koreanaornis hamanensis and Jindongornipes kimi sauropod footprint Brontopodus and ichnospecies Ochlichnus formed by Nematoda. This site has outstanding academic value because it is where the second-highest number of bird tracks have been reported in the world. However, only 25% of the site remains after being designated a natural monument in 1969. This is due to artificial damage caused by worldwide fame and quarrying for flat stone used in Korean floor heating systems. The Haman Formation, including this fossil site, has lithofacies showing reddish-grey siltstone and black shale, alternately. The boundary of the two rocks is progressive, and sedimentary structures like ripple marks and sun cracks can clearly be found. This site was divided into seven formations according to sedimentary sequences and structures. The results of a nondestructive deterioration evaluation showed that chemical and biological damage rates were very low for all formations. Also, physical damage displayed low rates with 0.49% on exfoliation, 0.04% on blistering, 0.28% on break-out; however, the joint crack index was high, 6.20. Additionally, efflorescence was observed on outcrops at the backside and the northwestern side. Physical properties measured by an indirect ultrasonic analysis were found to be moderately weathered (MW). Above all, the southeastern side was much fresher, though some areas around the column of protection facility appeared more weathered. Furthermore, five kinds of discontinuity surface can be found at this site, with the bedding plane showing the higher share. There is the possibility of toppling failure occurring at this site but stable on plane and wedge failure by means of stereographic projection. We concluded that the overall level of deterioration and stability were relatively fine. However, continuous monitoring and conservation treatment and management should be performed as situations such as the physicochemical weathering of the fossil layer, and the efflorescence of the mortar adjoining the protection facility's column appear to be challenging to control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.35-40
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• 2020

The ballast layers play a key role in distributing and supporting a trainload. On the other hand, it settles down by dynamic train loading due to large void ratios. Consequently, it requires continuous maintenance. In this paper, ballast layers mixed with three types of specially shaped artificial ballast (AB) (Rectangular, Tetrapod, Hexagonal) were modeled by using a two dimensional DEM (Discrete Element Method). Repeated loading tests were performed to evaluate the settlement behavior of the ballast layers. The smallest settlement was observed in the case of the ballast layer mixed with Tetrapod AB than in other cases, according to an analysis of the force transfer routes. In addition, contact force analysis showed that the Tetrapod AB, which has a concave shape, could easily make small and multi-channel force-transfer routes. This means that the stress in the ballast layer by the train loading transferred through the sleeper uniformly was distributed well by the AB. Therefore, the settlement of the ballast layer mixed with the concave-shaped Tetrapod AB could be reduced effectively under a repeated train loading. The effects of a decrease in settlement of the ballast layer highlight the possibility of a maintenance-free ballasted track.

• Journal of Korean Society of Transportation
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• v.24 no.3 s.89
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• pp.17-27
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• 2006

Car following model is a theory that examines changes of condition and interrelationship of acceleration deceleration. headway, velocity and so on closely based on the hypothesis that the Posterior vehicle always follows the preceding vehicle. Car following mode) which is one of the research fields of microscopic traffic flow was first introduced in 1950s and was in active progress in 1960s. However, due to the limitation of data gathering the research depression was prominent for quite a while and then soon was able to tune back on track with development in global positioning system using satellite and generalization of computer use. Recently, there has been many research studies using reception materials of global Positioning system(GPS). Introducing GPS technology to traffic has made real time tracking of a vehicle position possible. Position information is sequential in terms of time and simultaneous measurement of several vehicles in continuous driving is also practicable. Above research was focused on judging whether it is feasible to overcome the following model research by adopting the GPS reception device that was restrictively proceeded due to the limitation of data gathering. For practical judgment, we measured the accuracy and confidence level of the GPS reception devices material by carrying out a practical experiment. Car following model is also being applied in simulations of traffic flow analysis, but due to the difficulty of estimating parameters the basis of the above result. it is our goal to produce an accurate calibration of car following model's parameters that is suitable in this domestic actuality.

• Journal of Hospice and Palliative Care
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• v.4 no.2
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• pp.154-160
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• 2001

Purpose : This study, as the first year project of setting up a community based management system, was attempted for the cancer patients and their family to improve their quality of life; investigating and managing the cancer patients, educating volunteers and connecting the patients with the volunteers were performed. Method and result : The education of managing cancer patients for the volunteers was done once in lune for 2 days to the 80 volunteers. Questions about education effect, volunteer motivation and so on were made up. The survey showed, generally, education satisfaction level was high and a longer education and an intensive course were needed and was suggested that organizing a volunteer community be needed for the continuous further education and systematic management. As the result, after the public health center and volunteers deliberated, a volunteer community consisting of 4 teams, 28 members was organized, launched in Oct. and operated for the cancer patients and their family. For investigating and enrolling the patients, advertising on a local information paper, recommending of local doctors, publicizing by educating the heads of a subdivision of the city, the heads of a neighborhood association and the people in charge of the related local communities such as women's society, and surveying the community by volunteers were performed and the total, 41 patients were registered. Management of cancer patients was carried out by volunteers in a community and in a nursing school. A regional volunteers' community is composed of 23 members and they have worked 87 times, that is 3.8 times per capita on an average. The content of duties is attending the education (41.1%) the most. A volunteers' community of nursing students composed of 12 members have worked 135 times, that is 11.3 times per capita on an average. The content of duties - consulting with patients and home visiting (37.8 %) were the most and survey for investigating the cancer patients was the second. Conclusion : This study has the meaning that this is the guiding attempt in building a community based management system, and especially the achievement of this study is that a regional society organized a volunteer community for the cancer patients by itself and went into action for the cancer patients and their family. Furthermore, to activate this volunteering, it is necessary to keep managing volunteers and running continuing education or the intensive course of the volunteers. Indeed we should let the patients have good impression on this program through publicity and education for the residents to keep track of more cancer patients. For that, systematic and powerful cooperation of a self-administrative organization is required.