• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.3
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• pp.138-148
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• 2005

Dynamic response of floating structures such as floating body and floating bridges subject to wave load is to be calculated in frequency domain. Added mass coefficient, damping coefficient and wave exciting force are obtained numerically from frequency domain formulation of linear potential theory and boundary element method for a floating body which is partially submerged into water and subjected to wave force. Next, the equation of motion for the dynamic behavior of a floating structure which is supported by the floating bodies and modeled with finite elements is written in frequency domain. hker a hemisphere is analyzed and compared with the published references as examples of floating bodies, the hydrodynamic coefficients for a pontoon type floating body which supports a floating bridge are determined. The dynamic response of the floating bridge subject to design wave load can be solved using the coefficients obtained for the pontoons and the results are plotted in the frequency domain. It can be seen from the example analysis that although the peak frequency of the incoming wave spectrum is near the natural frequency of the bridge, the response of the bridge is not amplified due to the effect that the peak frequency of wave exciting force is away from the natural frequency of the bridge.

• Cartoon and Animation Studies
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• s.40
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• pp.337-365
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• 2015

The objective of this study proposes the new user's addiction model in 'Social Network Games' (SNGs). Research model is derived from the separation of two characteristics. First one is logical characteristics that includes 'Functional' (F), 'Keystroke' (K), and 'Goal' (G). Second one is feeling characteristics that consists a few factors such as 'Emotion' (E), 'Social' (S), and 'Affection' (A). For the pre-test, a total of 30 participants responded to survey in order to inspect the fitness of research questionnaire, roughly validity of the proposed model, and the direction of this reseach. After that for the main test, a total 300 users participated in this research. The final number of effective participants were 261 because 39 were insincere respondents and without playing SNGs who were excluded. Then we examined the measurement model by performing 'Partial Least Squares - Structural Equation Modeling' (PLS-SEM) analysis to test the research hypothesis empirically. The results of the measurement and structural model test lend support to the proposed research model by providing a good fit to the construct data. Interestingly, the model showed the significant effects of the interaction between eleven hypothesis(H1,H2,H3,H4,H5,H6,H7,H8,H9,H10, H12). Only one hypothesis decision t-value not supported that is involved the relationship between SNGs Addiction and Keystroke, H11(1.193). This research expect to contributes to an exploratory SNGs research to clarify the base of addition and will aids understanding of users' behavior associated with SNGs development.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.240-250
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• 2012

For this study, 373 students of H cyber university were chosen to conduct a survey in the spring semester of 2011. The result of this study through structural equation modeling analysis was as follows: First, organizational support significantly affected perceived isolation. Second, organizational support and perceived isolation significantly affected satisfaction. Third, perceived isolation and satisfaction significantly affected learning persistence, while organizational support didn't. In addition, satisfaction was verified as a mediating variable between organizational support, satisfaction, and learning persistence, and satisfaction was verified as a mediating variable between perceived isolation, organizational support and learning persistence. These results imply that perceived isolation and organizational support should be considered for the design and development strategies of instructional courses in order to enhance satisfaction and learning persistence of students in cyber educational environment.

• Geophysics and Geophysical Exploration
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• v.24 no.3
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• pp.89-97
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• 2021

Fault detection in seismic data is well suited to the application of machine learning algorithms. Accordingly, various machine learning techniques are being developed. In recent studies, machine learning models, which utilize synthetic data, are the particular focus when training with deep learning. The use of synthetic training data has many advantages; Securing massive data for training becomes easy and generating exact fault labels is possible with the help of synthetic training data. To interpret real data with the model trained by synthetic data, the synthetic data used for training should be geologically realistic. In this study, we introduce a method to generate realistic synthetic seismic data. Initially, reflectivity models are generated to include realistic fault structures, and then, a one-way wave equation is applied to efficiently generate seismic stack sections. Next, a migration algorithm is used to remove diffraction artifacts and random noise is added to mimic actual field data. A convolutional neural network model based on the U-Net structure is used to verify the generated synthetic data set. From the results of the experiment, we confirm that realistic synthetic data effectively creates a deep learning model that can be applied to field data.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.1-8
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• 2010

Seismic reflection surveying is one of the most widely used and effective techniques for coal seam structure delineation and risk mitigation for underground longwall mining. However, the ability of the method can be compromised by the presence of volcanic cover. This problem arises within parts of the Bowen and Sydney Basins of Australia and seismic surveying can be unsuccessful. As a consequence, such areas are less attractive for coal mining. Techniques to improve the success of seismic surveying over basalt flows are needed. In this paper, we use elastic wave-equation-based forward modelling techniques to investigate the effects and characteristics of seismic wave propagation under different settings involving changes in basalt properties, its thickness, lateral extent, relative position to the shot position and various forms of inhomogeneity. The modelling results suggests that: 1) basalts with high impedance contrasts and multiple flows generate strong multiples and weak reflectors; 2) thin basalts have less effect than thick basalts; 3) partial basalt cover has less effect than full basalt cover; 4) low frequency seismic waves (especially at large offsets) have better penetration through the basalt than high frequency waves; and 5) the deeper the coal seams are below basalts of limited extent, the less influence the basalts will have on the wave propagation. In addition to providing insights into the issues that arise when seismic surveying under basalts, these observations suggest that careful management of seismic noise and the acquisition of long-offset seismic data with low-frequency geophones have the potential to improve the seismic results.

• Journal of the Korean earth science society
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• v.41 no.5
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• pp.478-489
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• 2020

This study presents an analysis of infrasonic signals from two accidental explosions in Gwangyang city, Jeonnam Province, Korea, on December 24, 2019, recorded at 12 infrasound stations located 151-435 km away. Infrasound propagation refracted at an altitude of ~40 km owing to higher stratospheric wind in the NNW direction, resulting in favorable detection at stations in that direction. However, tropospheric phases were observed at stations located in the NE and E directions from the explosion site because of the strong west wind jet formed at ~10 km. The transmission losses on the propagation path were calculated using the effective sound velocity structure and parabolic equation modeling. Based on the losses, the observed signal amplitudes were corrected, and overpressures were estimated at the reference distance. From the overpressures, the source energy was evaluated through the overpressure-explosive charge relationship. The two explosions were found to have energies equivalent to 14 and 65 kg TNT, respectively. At the first explosion, a flying fragment forced by an explosive shock wave was observed in the air. The energy causing the flying fragment was estimated to be equivalent to 49 kg or less of TNT, obtained from the relationship between the fragment motion and overpressure. Our infrasound propagation modeling is available to constrain the source energy for remote explosions. To enhance the confidence in energy estimations, further studies are required to reflect the uncertainty of the atmospheric structure models on the estimations and to verify the relationships by various ground truth explosions.

• Geophysics and Geophysical Exploration
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• v.11 no.1
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• pp.68-77
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• 2008

We have developed an inversion algorithm for loop-loop electromagnetic (EM) data, based on the localised non-linear or extended Born approximation to the solution of the 2.5D integral equation describing an EM scattering problem. Source and receiver configuration may be horizontal co-planar (HCP) or vertical co-planar (VCP). Both multi-frequency and multi-separation data can be incorporated. Our inversion code runs on a PC platform without heavy computational load. For the sake of stable and high-resolution performance of the inversion, we implemented an algorithm determining an optimum spatially varying Lagrangian multiplier as a function of sensitivity distribution, through parameter resolution matrix and Backus-Gilbert spread function analysis. Considering that the different source-receiver orientation characteristics cause inconsistent sensitivities to the resistivity structure in simultaneous inversion of HCP and VCP data, which affects the stability and resolution of the inversion result, we adapted a weighting scheme based on the variances of misfits between the measured and calculated datasets. The accuracy of the modelling code that we have developed has been proven over the frequency, conductivity, and geometric ranges typically used in a loop-loop EM system through comparison with 2.5D finite-element modelling results. We first applied the inversion to synthetic data, from a model with resistive as well as conductive inhomogeneities embedded in a homogeneous half-space, to validate its performance. Applying the inversion to field data and comparing the result with that of dc resistivity data, we conclude that the newly developed algorithm provides a reasonable image of the subsurface.

• Information Systems Review
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• v.17 no.3
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• pp.159-181
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• 2015

This study proposes a comprehensive model of purchasing intention of customers in agricultural products online shopping malls. In this study, we derived the factors through the literature reviews and logical reasoning and classified the factors as a business point of view, an information systems point of view and an agricultural characteristics point of view, and developed the integrated research model which is the factors affect purchase intentions by mediating trust and the perceived usefulness. A total of 329 samples of a valid survey data from the members of small agricultural online shopping malls were collected and the research model was empirically analyzed by a confirmatory factor analysis and path analyses using structural equation modeling with the data. The results show that the product quality and the service quality of the business point of view have effects on the trust, however the price adequacy and entertainment have no effect on the trust and the perceived usefulness respectively, also the advertising exposure has no effect on the trust but it has an effect on the purchase intention directly. The information quality and the ease of use of the information systems point of view have an effect on the trust and perceived usefulness. At last, the seasonal product of the agricultural characteristics point of view has effects on perceived usefulness but the regional brand has no effect on the trust. The results of this study provide strategic implications for successful development and operation of agricultural products online shopping malls.

• Journal of Korea Society of Industrial Information Systems
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• v.26 no.6
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• pp.17-34
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• 2021

As knowledge management is recognized as an important factor for organizational performance, organizations are increasing their investment in knowledge management policies and technologies. The purpose of this study is to suggest positive and negative causes on the intention to share knowledge through a using knowledge management system(KMS) and to suggest the effect of organizational sharing climate. Research models and hypotheses were presented through previous studies, and 417 samples were obtained through the survey for employees of organizations that adopted a KMS. As a result of the analysis, usefulness and ease of use of the KMS had a positive effect on the intention to share knowledge, and task conflict and ambiguity had a negative effect. The knowledge sharing climate was found to be an antecedent for the technology acceptance model and task stress. In addition, task stress moderated the effect of usefulness and ease of use with the intention to share knowledge using KMS. The results suggested the direction to be pursued at the organizational level for the continuous use of KMS.

• The Journal of the Korea Contents Association
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• v.21 no.11
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• pp.333-349
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• 2021

As information is recognized as an important asset of an organization, organizations are increasing their resource input for knowledge management. In particular, the enterprise content management system(ECMS) is a solution for organization-oriented content management, and it has high utility by helping to achieve business performance through systematic utilization of content and improve the level of internal information security. The purpose of this study is to suggest a plan to improve the intention to use organizational employee's ECMS and to suggest the effect of the relationships between information system quality characteristics and work environment characteristics on intention to use. In this study, a research hypothesis was presented based on previous studies, a questionnaire was conducted on workers of organizations that adopted an ECMS, and the hypothesis was verified by applying structural equation modeling. As a result of the analysis, information and service quality of the ECMS and task interdependence increased the intention to use, but task conflict decreased the intention to use. In addition, task interdependence and task conflict moderated the positive relationship between the quality factors of the ECMS and the intention to use it. This study has implications in terms of suggesting the direction of the organization's behavior through factors that increase the use of ECMS.