• Journal of Integrative Natural Science
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• v.14 no.2
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• pp.41-49
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• 2021

The causes of climate change are natural and artificial. Natural causes include changes in temperature and sunspot activities caused by changes in solar radiation due to large-scale volcanic activities, while artificial causes include increased greenhouse gas concentrations and land use changes. Studies have shown that excessive carbon use among artificial causes has accelerated global warming. Climate change is rapidly under way because of this. Due to climate change, the frequency and cycle of infectious disease viruses are greater and faster than before. Currently, the world is suffering greatly from coronavirus infection-19 (COVID-19). Korea is no exception. The first confirmed case occurred on January 20, 2020, and the number of infected people has steadily increased due to several waves since then, and many confirmed cases are occurring in 2021. In this study, we conduct a study on climate change before and after COVID-19 using weather data from Korea to determine whether climate change affects infectious disease viruses through logistic regression analysis. Based on this, we want to classify before and after COVID-19 through a logistic regression model to see how much classification rate we have. In addition, we compare monthly classification rates to see if there are seasonal classification differences.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.657-665
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• 2021

The study aims to assess the acceptance of social commerce and participate in social commerce amongst Omani people. The questions of the survey Instrument were prepared in English later converted into Arabic. The survey instrument was having two parts; the first part sought the demographic information like age, gender, education, occupation etc. The second part of the instrument was related to the variables, which was in 5-point Likert scale, where 5 means strongly agree while 1 meaning strongly disagree. The data was collected using online and offline surveys, making the number of the valid responses to 478. A conceptual model was developed using the following variables. The selected variables such as "Familiarity" (F), "Trust" (T), "Perceived usefulness" (PU), "Perceived ease of use" (PEU), "Intention to Purchase" (IP). The hypothesis was tested using structural equation modelling. The results indicate that all six hypotheses were supported. The F, T and PEU, and PU was found to be positive and significant related to intention to purchase (p-value 0.003, 0.001, 0.000. & 0.007). Amongst the four, p value of F was found to be the lowest and PU was found to be the highest. This indicate F was strong indicator of IP as compared to others. PUE relates to PU, and F was related to IP.

• Wind and Structures
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• v.32 no.5
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• pp.453-469
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• 2021

Snow accumulation on the road frequently induces a big traffic problem in the cold snowy region. Accurate prediction on snow distribution is fundamental for solving drifting snow disasters on roads. The present study adopts the transient method to simulate the wind-induced snow distribution on embankment based on the mixture multiphase model and dynamic mesh technique. The simulation and field measurement are compared to confirm the applicability of the simulation. Furthermore, the process of snow accumulation is revealed. The effects of friction velocity and snow concentration on snow accumulation are analyzed to clarify its mechanism. The results show that the simulation agrees well with the field measurement in trends. Moreover, the snow accumulation on the embankment can be approximately divided into three stages with time, the snow firstly deposited on the windward side, then, accumulation occurs on the leeward side which induced by the wake vortex, finally, the snow distribution reaches an equilibrium state with the slope of approximately 7°. The friction velocity and duration have a significant influence on the snow accumulation, and the vortex scale directly affected the snow deposition range on the embankment leeward side.

• Steel and Composite Structures
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• v.39 no.4
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• pp.353-366
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• 2021

Cored moment resisting stub column (CMSC) was previously developed by the features of adopting a core segment which remains mostly elastic and reduced column section (RCS) details around the ends to from a stable hysteretic behavior with large post-yield stiffness and considerable ductility. Several full-scale CMSC components with various length proportions of the RCSs with respect to overall lengths have been experimentally investigated through both far-field and near-fault cyclic loadings followed by fatigue tests. Test results verified that the proposed CMSC provided very ductile hysteretic responses with no strength degradation even beyond the occurrence of the local buckling at the side-segments. The effect of RCS lengths on the seismic performance of the CMSC was verified to relate with the levels of the deformation concentration at the member ends, the local buckling behavior and overall ductility. Estimation equations were established to notionally calculate the first-yield and ultimate strengths of the CMSC and validated by the measured responses. A numerical model of the CMSC was developed to accurately capture the hysteretic performance of the specimens, and was adopted to clarify the effect of the surrounding frame and to perform a parametric study to develop the estimation of the elastic stiffness.

• Journal of Hydrogen and New Energy
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• v.30 no.5
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• pp.448-454
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• 2019

This paper presents a high-efficiency design technique for developing the serialized models of a single-channel pump based on the diameter, flow rate and head as the main performance parameters. The variation in pump performance by changing of the single-channel pump geometry was predicted based on computational fluid dynamics (CFD). Numerical analysis was conducted by solving three-dimensional steady Reynolds-averaged Navier-Stokes equations with the shear stress transport (SST) turbulence model. The tendencies of the hydraulic performance depending on the pump geometry scale were analyzed with the fixed rotational speed. These performances were expressed and evaluated as the functionalization for designing the serialized models of a single-channel pump in this work.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.6_2
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• pp.1081-1091
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• 2020

The most recent issue of offshore plants that produce oil and gas are the decommissioning engineering of aged or discontinued platforms. There are many platforms that are being dismantled in the United States, Europe, and areas in Southeast Asia. In particular, more than 400 old platforms in Southeast Asia (Indonesia, Malaysia) are preparing to dismantle. They are spread out across Southeast Asia with a water level of 50 meters and small-scale of less than 10,000 tons. However, this offshore plant decommissioning market is a very suitable market for small and medium-sized shipyards in Korea to enter with their established equipment and engineers. Platform decommissioning is conducted according to decommissioning procedures. However, there are some difficulties in market advances as no developed case studies or process models are established on how platform structures and components are to be dismantled and how the dismantled material is to be reused and recycled. Therefore, this study presented domestic and foreign regulations on the reuse and recycling of oil and gas producing offshore plant platforms, case analyses on developed decommissioning engineering, platform reuse and recycling guidelines, and platform and pipeline decommissioning processes and methods.

• Korean Journal of Childcare and Education
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• v.16 no.6
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• pp.89-104
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• 2020

Objective: The purpose of this study was to examine the effects of maternal parenting stress and mother's ego-resilience on mother-child attachment. More specially, mother-child attachment for higher grade elementary school children was examined according to the internal working model. Methods: Participants were 190 mothers of fourth and fifth grade elementary school children. The Maternal Parenting Stress Scale(Shin, 1997), the Scales of Ego-resilience(Yoo & Shim, 2002), and Inventory of Parent Attachment(Yang, 2006) were used to measure variables. Collected data were analyzed by descriptive statistics, t-test, correlation analysis and multiple regression analysis. Results: The major findings were summarized as follows: First, there were no differences between mother-child attachment according to children's gender. Second, mother-child attachment was negatively correlated with maternal parenting stress and positively correlated with ego-resilience. Next, maternal parenting stress_interaction and ego-resilience explained mother-child attachment_trust. Last, maternal stress_interaction explained mother-child attachment_isolation. Conclusion/Implications: In conclusion, the study results showed that maternal parenting stress and ego-resilience influenced mother-child attachment. based on the results, the implications of this study were discussed.

• Wind and Structures
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• v.32 no.2
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• pp.105-114
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• 2021

This paper describes a wind tunnel test on a 1:25 scale model of TTU building with several adjustable openings in order to comprehensively study the characteristics of fluctuating internal pressures, especially the phenomenon of the increase in fluctuating internal pressures induced by tangential flow over building openings and the mechanism causing that. The effects of several factors, such as wind angle, turbulence intensity, opening location, opening size, opening shape and background porosity on the fluctuating internal pressures at oblique wind angles are also described. It has been found that there is a large increase in the fluctuating internal pressures at certain oblique wind angles (typically around 60° to 80°). These fluctuations are greater than those produced by the flow normal to the opening when the turbulence intensity is low. It is demonstrated that the internal pressure resonances induced by the external pressure fluctuations emanating from flapping shear layers on the sidewall downstream of the windward corner are responsible for the increase in the fluctuating internal pressures. Furthermore, the test results show that apart from the opening shape, all the other factors influence the fluctuating internal pressures and the internal pressure resonances at oblique wind angles to varying degrees.

• Earthquakes and Structures
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• v.19 no.6
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• pp.459-469
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• 2020

An external prestressed steel-bar truss unit was developed as a new strengthening technology to enhance the seismic performance of an in-plane masonry wall structure while taking advantage of the benefits of a prestressed system. The presented method consists of six steel bars: two prestressed vertical bars to introduce a prestressing force on the masonry wall, two diagonal bars to resist shear deformation, and two horizontal bars to maintain the configuration. To evaluate the effects of this new technique, four full-scale specimens, including a control specimen, were tested under combined loadings that included constant-gravity axial loads and cyclic lateral loads. The experimental results were analyzed in terms of the shear strength, initial stiffness, dissipated energy, and strain history. The efficiency of the external prestressed steel-bar truss unit was validated. In particular, a retrofitted specimen with an axial load level of 0.024 exhibited a more stable post behavior and higher energy dissipation than a control specimen with an observed complete sliding failure. The four vertical bars of the adjacent retrofitting units created a virtual column, and their strain values did not change until they reached the peak shear strength. The shear capacity of the masonry wall structure with external prestressed steel-bar truss units could be predicted using the model suggested by Yang et al.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.1257-1266
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• 2021

The study examines factors that influence shopping intention of online consumers in Vietnam. Studied factors include consumers' attitude, subjective norms, perception of behavioral control, perception of usefulness, perceived risks and trust. The expansion of Theory of Planned Behavior (TPB) and Technology Acceptance Model (TAM) are used as basic theories. We have surveyed people who have experiences on online shopping. There are 836 selected questionnaires that are qualified for data processing. The collected data are analyzed through a process which starts from scale reliability test to exploratory factor analysis (EFA), correlation analysis and regression analysis. The results show that shopping intention of online consumers are positively affected by their attitude, subjective norms, perception of behavioral control, perception of usefulness and trust. In contrast, online shopping intention is negatively affected by the perceived risks that online shopping could bring. Among those factors, the perception of risk is shown to have the strongest influence to online shopping intention. The findings of this study suggest that managers and retailers can apply cash-on-delivery method and design their website with user-friendly interface to enhance online shopping intention of consumers. The Government is also recommended to fulfill the law system to reduce customers' perception of financial risks.