• The Journal of the Acoustical Society of Korea
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• v.41 no.1
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• pp.64-69
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• 2022

Background music is presented simultaneously with target messages. The main content should be kept intact for some time to aid decision making process. The maintenance of this information requires auditory working memory. The temporal compression of background music may often adopted due to the limitation of the presentation time. In this study, auditory working memory and decision making proces were analyzed in terms of temporal compression ratios of the background music. A total of 37 subjects of early twenties joined the study. Selected products were categorized based on eigen values of multi-dimensional scaling. Four presentation conditions were cases with no background music, background music with no compression, background music with low compression, and background music high compression. Matched reponses were analyzed through repeated ANOVA. Results showed that the high involvement product required more working memory resources. However, the increased level of usage did not always lead to the corresponding changes in decision making process. This approach may be useful in analyzing the role of time compression and working memory in consumer behaviors.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.3
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• pp.231-245
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• 2022

When vertical shafts are constructed in soft clay with low strength, there is a risk of basal heave, which causes the excavation surface to heave due to the low bearing capacity of the ground against the imbalance of earth pressure at the excavation surface. Methods of deriving a safety factor have been proposed to evaluate the stability against the basal heave. However, there are limitations in that it is difficult to accurately evaluate the heave stability because many assumptions are included in the theoretical derivation. In this study, assuming that a circular vertical shaft is constructed in soft clay, the existing safety factor equation proposed through a theoretical approach was supplemented. Bearing capacity according to the shaft geometry, inhomogeneity of the soil, and the effect of soil plug were considered theoretically and applied in a previous safety factor equation. A three-dimensional numerical analysis was conducted to simulate the occurrence of basal heave and review the supplemented equation through various case studies. Several series of case studies were conducted targeting various factors affecting heave stability. It was verified that the additionally considered characteristics were properly reflected in the supplemented equation. Furthermore, the effects of each factor constituting the safety factor equation were examined using the results of the numerical analysis performed by simulating various cases. It was confirmed that considering the undrained shear strength increment according to depth had the most significant effect on the calculation of the safety factor.

• Nuclear Engineering and Technology
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• v.25 no.4
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• pp.539-547
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• 1993

A stochastic approach using continuous time Markov process is presented to model the one-dimensional nuclide transport in fractured rock media as a further extension for previous works［1-3］. Nuclide transport of decay chain of arbitrary length in the single planar fractured rock media in the vicinity of the radioactive waste repository is modeled using a continuous time Markov process. While most of analytical solutions for nuclide transport of decay chain deal with the limited length of decay chain, do not consider the case of having rock matrix diffusion, and have very complicated solution form, the present model offers rather a simplified solution in the form of expectance and its variance resulted from a stochastic modeling. As another deterministic way, even numerical models of decay chain transport, in most cases, show very complicated procedure to get the solution and large discrepancy for the exact solution as opposed to the stochastic model developed in this study. To demonstrate the use of the present model and to verify the model by comparing with the deterministic model, a specific illustration was made for the transport of a chain of three member in single fractured rock medium with constant groundwater flow rate in the fracture, which ignores the rock matrix diffusion and shows good capability to model the fractured media around the repository.

• Journal of Christian Education in Korea
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• v.74
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• pp.57-80
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• 2023

The purpose of this study is to review the practicality of Christian education for sustainable development in a rapidly changing world. The first part of this study identify the concept, meaning, and direction of implementation of "Sustainable Development," which has been studied and published around UNESCO since the early 1980s, and present practical strategies for the sustainable development of Christian education. This study chronologically selected five major reports published by UNESCO--"Our Common Future"(1987), "Agenda 21"(1992), "UN Decade of Education for Sustainable Development 2005-2014"(2002), "Roadmap for Implementing the Global Action Programme for Education for Sustainable Development 2015-2019"(2014) and "Education for Sustainable Development 2030"(2020)--and examined the concept and meaning of "Sustainable Development"(SD). At the same time, in relation to "Education for Sustainable Development"(ESD), the occurrence, change, and implementation method of "Sustainable Development Goals"(SDGs) were examined and presented. This study derived three Christian educational implications necessary to properly establish the next generation of faith, based on a leadership development strategy using the concept of sustainable development, For the sustainability of Christian education, the foundation of education based on the correct biblical interpretation of cultural mandate is first examined, and then the need for curriculum development and class design is proposed using various types of indicators and educational modules. Finally, specific practices for the development of educational leadership to revitalize Christian education are presented through a multi-dimensional approach.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5B
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• pp.575-589
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• 2008

In the present work, we investigate the hydrodynamic behavior of a turbulent bore, such as tsunami bore and tidal bore, generated by the removal of a gate with water impounded on one side. The bore generation system is similar to that used in a general dam-break problem. In order to the numerical simulation of the formation and propagation of a bore, we consider the incompressible flows of two immiscible fluids, liquid and gas, governed by the Navier-Stokes equations. The interface tracking between two fluids is achieved by the volume-of-fluid (VOF) technique and the M-type cubic interpolated propagation (MCIP) scheme is used to solve the Navier-Stokes equations. The MCIP method is a low diffusive and stable scheme and is generally extended the original one-dimensional CIP to higher dimensions, using a fractional step technique. Further, large eddy simulation (LES) closure scheme, a cost-effective approach to turbulence simulation, is used to predict the evolution of quantities associated with turbulence. In order to verify the applicability of the developed numerical model to the bore simulation, laboratory experiments are performed in a wave tank. Comparisons are made between the numerical results by the present model and the experimental data and good agreement is achieved.

• Steel and Composite Structures
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• v.46 no.1
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• pp.53-73
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• 2023

Man-made structure materials like concrete usually contain inclusions. These inclusions affect the mechanical properties of concrete. In this investigation, the influence of inclusion length and inclination angle on three-dimensional failure mechanism of concrete under uniaxial compression were performed using experimental test and numerical simulation. Approach of acoustic emission were jointly used to analyze the damage and fracture process. Besides, by combining the stress-strain behavior, quantitative determination of the thresholds of crack stress were done. concrete specimens with dimensions of 120 mm × 150 mm × 100 mm were provided. One and two holes filled by gypsum are incorporated in concrete samples. To build the inclusion, firstly cylinder steel tube was pre-inserting into the concrete and removing them after the initial hardening of the specimen. Secondly, the gypsum was poured into the holes. Tensile strengths of concrete and gypsum were 2.45 MPa and 1.5 MPa, respectively. The angle bertween inclusions and axial loadind ary from 0 to 90 with increases of 30. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Diameter of the hole was 20 mm. Entirely 20 various models were examined under uniaxial test. Simultaneous with experimental tests, numerical simulation (Particle flow code in two dimension) were carried out on the numerical models containing the inclusions. The numerical model were calibrated firstly by experimental outputs and then failure behavior of models containing inclusions have been investigated. The angle bertween inclusions and axial loadind vary from 0 to 90 with increases of 15. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Entirely 32 various models were examined under uniaxial test. Loading rate was 0.05 mm/sec. The results indicated that when inclusion has occupied 100% of sample thickness, two tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusion has occupied 75% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusions have occupied 50% and 25% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. Also the inclusion was failed by one tensile crack. The compressive strength of samples decease with the decreases of the inclusions length, and inclusion angle had some effects on that. Failure of concrete is mostly due to the tensile crack. The behavior of crack, was affected by the inclusion length and inclusion number.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.279-289
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• 2006

The reconstruction of low dimension nonlinear behavior from the hydrologic time series has been an active area of research in the last decade. In this study, we present the applications of a powerful state space reconstruction methodology using the method of Support Vector Machines (SVM) to the Great Salt Lake (GSL) volume. SVMs are machine learning systems that use a hypothesis space of linear functions in a Kernel induced higher dimensional feature space. SVMs are optimized by minimizing a bound on a generalized error (risk) measure, rather than just the mean square error over a training set. The utility of this SVM regression approach is demonstrated through applications to the short term forecasts of the biweekly GSL volume. The SVM based reconstruction is used to develop time series forecasts for multiple lead times ranging from the period of two weeks to several months. The reliability of the algorithm in learning and forecasting the dynamics is tested using split sample sensitivity analyses, with a particular interest in forecasting extreme states. Unlike previously reported methodologies, SVMs are able to extract the dynamics using only a few past observed data points (Support Vectors, SV) out of the training examples. Considering statistical measures, the prediction model based on SVM demonstrated encouraging and promising results in a short-term prediction. Thus, the SVM method presented in this study suggests a competitive methodology for the forecast of hydrologic time series.

• Journal of Service Research and Studies
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• v.13 no.4
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• pp.160-172
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• 2023

The metaverse, derived from the fusion of "meta" and "universe," encompasses a three-dimensional virtual realm where avatars actively participate in a range of political, economic, social, and cultural activities. With the recent development of the metaverse, the traditional way of experiencing services is changing. While existing studies have mainly focused on the technological advancements of metaverse services (e.g., scope of technological enablers, application areas of technologies), recent studies are focusing on evaluating the quality of experience (QoE) of metaverse services from a customer perspective. This is because understanding and analyzing service characteristics that determine QoE from a customer perspective is essential for designing successful metaverse services. However, relatively few studies have explored the customer-oriented approach for QoE evaluation thus far. This study conducted an online review analysis using text mining to overcome this limitation. In particular, this study analyzed 227,332 online reviews of the Roblox service, known as a representative metaverse service, and identified points for improving the Roblox service based on the analysis results. As a result of the study, nine service features that can be used for QoE evaluation of metaverse services were derived, and the importance of each feature was estimated through relationship analysis with service satisfaction. The importance estimation results identified the "co-experience" feature as the most important. These findings provide valuable insights and implications for service companies to identify their strengths and weaknesses, and provide useful insights to gain an advantage in the changing metaverse service environment.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.5
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• pp.315-324
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• 2023

In this paper, we propose a real-time pose estimation method for a monocular camera using a particle filter integrated with UKF (unscented Kalman filter). While conventional camera tracking techniques combine camera images with data from additional devices such as gyroscopes and accelerometers, the proposed method aims to use only two-dimensional visual information from the camera without additional sensors. This leads to a significant simplification in the hardware configuration. The proposed approach is based on a particle filter integrated with UKF. The pose of the camera is estimated using UKF, which is defined individually for each particle. Statistics regarding the camera state are derived from all particles of the particle filter, from which the real-time camera pose information is computed. The proposed method demonstrates robust tracking, even in the case of rapid camera shakes and severe scene occlusions. The experiments show that our method remains robust even when most of the feature points in the image are obscured. In addition, we verify that when the number of particles is 35, the processing time per frame is approximately 25ms, which confirms that there are no issues with real-time processing.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.345-352
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• 2024

K-Pop Square Media, located at COEX in Samseong-dong, has gained public attention and mass media focus by showcasing various three-dimensional videos on a large LED display. The video content on the distinctive large curved LED display utilizes a form of media façade technique, establishing itself as a new landmark and attraction within the spatial characteristics of the COEX Plaza. This study aims to examine the characteristics of media facades used in outdoor advertising in urban spaces, focusing on K-Pop Square Media. The approach for this research involves three aspects: Firstly, examining the 'spatial characteristics' of urban public spaces by referencing Kevin Lynch's five elements constituting urban space and William J. Mitchell's exploration of smart spaces and changes in spatial paradigms. Secondly, analyzing the 'digital nature' of outdoor advertising through an examination of three types of Digital Out-Of-Home (DOOH) Media. Thirdly, exploring the 'technological advancements and content composition of media facades' by investigating types of display media (projection, LED screens), the inception of media facades, and the latest display technology like Anamorphic displays. Through this research, it becomes evident that K-Pop Square Media exhibits characteristics of publicness, communicativeness, artistry, and placemaking through the spatial characteristics of smart spaces, the media-specific aspects of Digital Out-Of-Home advertising, and the content composition of media facades.