• The Journal of the Korea Contents Association
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• v.21 no.3
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• pp.576-589
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• 2021

Live commerce as a new form of service that combines live streaming service with e-commerce is gaining a growing attention from many people with diffusion of a new trend of untact economy. In this context, this research examines what leads to user satisfaction of live commerce. In especial, this research conceptualized several determinants that might affect user satisfaction of live commerce from three dimensions of users, information sources and platforms. It also tested whether those factors had influences on user satisfaction of live commerce empirically. The sample in this study was responses of 218 people in their 20s and 30s who had experienced using live commerce. They were analyzed using a hierarchical regression analysis. The findings revealed that depression and innovativeness from the dimension of users, attractiveness of show host from that of information sources, and physical affordance and perceived interaction among users from that of platforms had significant influences on user satisfaction of live commerce.

• The Journal of Advanced Prosthodontics
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• v.14 no.2
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• pp.96-107
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• 2022

PURPOSE. Microstructural and physico-mechanical characterization of highly translucent zirconia, prepared by milling technology (CAD-CAM) and repeated firing cycles, was the main aim of this in vitro study. MATERIALS AND METHODS. Two groups of samples of two commercial highly-translucent yttria-stabilized dental zirconia, VITA YZ-HT^White (Group A) and Zolid HT + White (Group B), with dimensions according to the ISO 6872 "Dentistry - Ceramic materials", were prepared. The specimens of each group were divided into two subgroups. The specimens of the first subgroups (Group A₁ and Group B₁) were merely the sintered specimens. The specimens of the second subgroups (Group A₂ and Group B₂) were subjected to 4 heat treatment cycles. The microstructural features (microstructure, density, grain size, crystalline phases, and crystallite size) and four mechanical properties (flexural strength, modulus of elasticity, Vickers hardness, and fracture toughness) of the subgroups (i.e. before and after heat treatment) were compared. The statistical significance between the subgroups (A₁/A₂, and B₁/B₂) was evaluated by the t-test. In all tests, P values smaller than 5% were considered statistically significant. RESULTS. A homogenous microstructure, with no residual porosity and grains sized between 500 and 450 nm for group A and B, respectively, was observed. Crystalline yttria-stabilized tetragonal zirconia was exclusively registered in the X-ray diffractograms. The mechanical properties decreased after the heat treatment procedure, but the differences were not statistically significant. CONCLUSION. The produced zirconia ceramic materials can be safely (i.e., according to the ISO 6872) used in extensive fixed prosthetic restorations, such as substructure ceramics for three-unit prostheses involving the molar restoration and substructure ceramics for prostheses involving four or more units. Consequently, milling technology is an effective manufacturing technology for producing zirconia substructures for dental fixed all-ceramic prosthetic restorations.

• Journal of Information Technology Services
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• v.21 no.4
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• pp.1-26
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• 2022

Recently, the number of cases of purchasing food online has been increased, especially in the open market. Therefore, we examined the characteristics of status quo bias and switching costs in the open market. Also, in this study, the causal relationship between the characteristics of status quo bias and switching costs, switching costs and switching intention in the open market was investigated. The analysis result consists of four parts as follows. First, in the open market, rational decision making, which belongs to the characteristics of status quo bias, was found to have a positive (+) effect on time switching cost among switching costs, but did not have a positive (+) effect on economic and psychological switching cost. Second, cognitive misperceptions was consistent with the assumption that it have a positive (+) effect on all of the economic, time, and psychological switching cost, which are switching costs in the open market. Third, psychological commitment was found to have a positive (+) effect on economic and time switching cost among switching costs, but did not have a positive (+) effect on psychological switching cost. Fourth, psychological switching cost, which belongs to switching costs in the open market, was found to have a negative (-) effect like the hypothesis set in switching intention. However, it was found that economic and time switching cost did not have a negative (-) effect on switching intention. This study subdivided the switching costs into three dimensions and compared the degree of influence on the switching intention, and the degree of influence was different for each dimension. Therefore, it was found that when switching from the existing open market to the new open market, it is not possible to simply judge that the switching costs directly has a negative (-) effect on the switching intention or does not.

• Korean Journal of Applied Biomechanics
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• v.32 no.3
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• pp.87-93
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• 2022

Objective: The purpose of this research was to investigate the age-related changes in whole-body motor variability during sit-to-stand (STS) task. It has been reported that children perform motor tasks less accurately with greater variability as compared to adults. However, it is still unknown how they utilize the abundant degrees of freedom and accomplish voluntary actions. Uncontrolled manifold (UCM) analysis has been used to partition motor variabilities into two independent variability components, task-relevant variability (V_ORT) and task-irrelevant variability (V_UCM). We investigated what differences exist between children and adults with respect to these two motor variability components in relation to motor development stages. Method: Ten 6-year-old children (height: 116.2 ± 4.3 cm, weight: 23.1 ± 3.9 kg, motor development assessment percentile score: 77.5 ± 18.6%), ten 10-year-old children (height: 138.7 ± 7.2 cm, weight: 35.8 ± 10.3 kg, motor development assessment percentile score: 73.9 ± 12.7%), and ten young adults (age: 23 ± 1.6 year-old, height: 164.3 ± 11.4 cm, weight: 60.8 ± 12.0 kg) participated in this study. Each participant performed STS ten times, and a motion capture system was used to capture the whole-body kinematics. Each segment centers of mass and the whole-body center of mass were calculated, and UCM analysis was used to quantify motor variabilities, V_ORT and V_UCM. One-way ANOVA was used for statistical analysis. Results: We found that children produced more motor variabilities in V_ORT and V_UCM in all three dimensions, anterior-posterior, medial-lateral, and vertical. As age increased, both, V_ORT and V_UCM significantly decreased (p<.05). Conclusion: The greater V_ORT found in children compared to adults indicates that the repeatability over repetitions improves through development, while the greater V_UCM found in children suggests that children better utilize the abundant degrees of freedom during STS compared to adults.

• Smart Structures and Systems
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• v.30 no.1
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• pp.49-62
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• 2022

Experimental and discrete element methods were used to investigate the effects of triple joints lengths and triple joint angle on the failure behavior of rock mass under uniaxial compressive test. Concrete samples with dimension of 20 cm × 20 cm × 5 cm were prepared. Within the specimen, three imbedded joint were provided. The joint lengths were 2 cm, 4cm and 6 cm. In constant joint lengths, the angle between middle joint and other joints were 30°, 60°, 90°, 120° and 150°. Totally 15 different models were tested under compression test. The axial load rate on the model was 0.05 mm/min. Concurrent with experimental tests, the models containing triple joints, length and joint angle are similar to the experiments, were numerical by Particle flow code in two dimensions (PFC2D). Loading rate in numerical modelling was 0.05 mm/min. Tensile strength of material was 1 MPa. The results show that the failure behaviors of rock samples containing triple joints were governed by both of the angle and the length of the triple joints. The uniaxial compressive strengths (UCS) of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. Furthermore, it was shown that the compressive behavior of discontinuities is related to the number of the induced tensile cracks which are increased by decreasing the joint length. Along with the damage failure of the samples, the acoustic emission (AE) activities are excited. There were only a few AE hits in the initial stage of loading, then AE hits rapidly grow before the applied stress reached its peak. In addition, every stress drop was accompanied by a large number of AE hits. Finally, the failure pattern and failure strength are similar in both methods i.e., the experimental testing and the numerical simulation methods.

• Composites Research
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• v.35 no.6
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• pp.463-468
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• 2022

The high porosity of the infill pattern of carbon chopped fiber-reinforced Nylon composite structures fabricated by the fused filament fabrication (FFF) type 3D printers determines the mechanical performance of the printed structures. This study experimentally evaluated the mechanical performance of Onyx composite specimens fabricated with a rectangular infill structure under the hot-pressing condition to improve the mechanical properties by reducing the porosity of the infill pattern of the printed structure, and evaluated the best mechanical performance. The hot-pressing conditions (145℃, 4 MPa, 12 min) that induce the most appropriate mechanical properties were found. As a result of microscopic observation, it was confirmed that the infill porosity of the composite specimens subjected to post hot-pressing treatment was effectively reduced. In order to confirm the mechanical performance of the post-treated specimen, a tensile test and a three-point bending test were performed with a control specimen without post-treatment and a specimen printed with the same density and dimensions after post-treatment to evaluate the mechanical properties. As a result of comparison, it was confirmed that the mechanical properties were effectively improved when the post-treatment of hot-pressing was performed.

• Journal of Internet Computing and Services
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• v.23 no.6
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• pp.71-78
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• 2022

This paper proposes an algorithm for 3D object detection by processing point cloud data of 3D LiDAR. Unlike 2D LiDAR, 3D LiDAR-based data was too vast and difficult to process in three dimensions. This paper introduces various studies based on 3D LiDAR and describes 3D LiDAR data processing. In this study, we propose a method of processing data of 3D LiDAR using clustering techniques for object detection and design an algorithm that fuses with cameras for clear and accurate 3D object detection. In addition, we study models for clustering 3D LiDAR-based data and study hyperparameter values according to models. When clustering 3D LiDAR-based data, the DBSCAN algorithm showed the most accurate results, and the hyperparameter values of DBSCAN were compared and analyzed. This study will be helpful for object detection research using 3D LiDAR in the future.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.89-96
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• 2022

This study examines the strategy of delivering the drama's poet Kim Soo-young and his literary works to the public through the drama (2004). This drama shows Kim's inner self and his literary view by inserting poems into scenes where the poet suffers internal conflict, while presenting relatively less well-known poems to broaden the public's understanding of poetry. In addition, the drama maintains viewers' interest by properly placing elements of conflict, and effectively shows how the conflict affected his life and the world of time. Therefore, the drama is a meaningful text that embodies a poet named Kim Soo-young in three dimensions along with the historical transformation and social problems of the time and the literary chapter of the time through the video.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.9
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• pp.299-307
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• 2022

The goal of the study is to examine and assess how the factors of logistics service quality provided by logistics service providers influence customer loyalty and satisfaction in Vietnam. This study employs samples of the Kansei technique. The article's data was gathered through an online survey of 388 distinct Vietnamese customers who used logistics services before and during the Covid-19 outbreak. After the data was obtained, it was evaluated using SmartPLS 3.0's Cronbach's Alpha test and structural equation model (SEM). Staff service quality, operational service quality, and technical service quality are the three factors that determine the quality of logistics services in the study. Out of the 10 proposed hypotheses, research findings show that five are acceptable. The Covid-19 Pandemic in Vietnam had a significant impact on all dimensions, but it had no effect on how satisfied customers were with the logistics service providers. Nevertheless, loyalty is considerably influenced by only one factor, which is customer satisfaction, and customer trust moderates the relationship between these two factors. As a consequence of that, several managerial implications have been proposed to help logistics service providers improve their services to attract and keep Vietnamese customers using their service in the long term.

• Journal of the Korea Society of Computer and Information
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• v.27 no.8
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• pp.23-30
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• 2022

Deep learning analyzes data to discover a series of rules and anticipates the future, helping us in various ways in our lives. For example, prediction of stock prices and agricultural prices. In this research, the results of solar photovoltaic power generation accompanied by weather are analyzed through deep learning in situations where the importance of solar energy use increases, and the amount of power generation is predicted. In this research, we propose a model using LSTM(Long Short Term Memory network) that stand out in time series data prediction. And we compare LSTM's performance with CNN(Convolutional Neural Network), which is used to analyze various dimensions of data, including images, and CNN-LSTM, which combines the two models. The performance of the three models was compared by calculating the MSE, RMSE, R-Squared with the actual value of the solar photovoltaic power generation performance and the predicted value. As a result, it was found that the performance of the LSTM model was the best. Therefor, this research proposes predicting solar photovoltaic power generation using LSTM.