• Journal of Wetlands Research
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• v.23 no.2
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• pp.107-115
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• 2021

In order to analyze wave propagation, tidal current, and sediment transport in the vicinity of the Gaeya open channel, it was classified into before(CASE1W) and after(CASE2W) installation of various artificial structures, and the calculation results for CASE1W and CASE2W were compared. For wave propagation, the results of incident and reflected waves were derived using the SWAN numerical model, and the tidal current velocity results were derived using the FLOW2DH numerical model for tidal current. The results of the SWAN numerical model and the FLOW2DH numerical model became the input conditions for the SEDTRAN numerical model that predicts sediment transport, and the maximum bed shear stress and suspended sediment concentration distribution near the Gaeya open channel were calculated through the SEDTRAN numerical model. As a result of the calculation of the SWAN numerical model, the wave height of CASE2W was increased by 40~50 % compared to CASE1W because the incident wave was diffracted and superimposed and the reflected wave was generated by about 7 km long northen jetty. As a result of the calculation of the FLOW2DH numerical model, According to the northen breakwater, the northen jetty and Geumrando, CASE2W was calculated 10~30 % faster than CASE1W in the tidal current of the Gaeya open channel. As a result of the calculation of the SEDTRAN numerical model, the section where the maximum bed shear stress is 1.0 N/m² or more and the suspended concentration is 80mg/L or more was widely distributed in the Gaeya open channel from the marine environment by the complex wave field(incident wave, reflected wave and tidal wave) and the installation of various artificial structures. it is believed that a sedimentation phenomenon occurred in the Gaeya open channel.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.119-125
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• 2020

Research on high-attenuation concrete for the vibration reduction performance by mixing epoxy-based synthetic resins and aggregates is actively being conducted. The curing time of high-attenuation concrete is very short because water is not used, and the physical and dynamic properties are very excellent. therefore, it is expected to be widely used in building structures requiring reduction of interior-floor noise and vibration. Furthermore, A way to expand the applicability of the high-damping concrete mixed with polymer in the field of reinforcement material have been variously studied. In order to replace polymer concrete with ordirnary concrete and existing anti-vibration reinforcement material, it is necessary to review overall vibration reduction performance considering physical properties, dynamic properties, productivity and field applicability. In this study, the physical and dynamic properties of polymer concrete by epoxy mixing ratio compared with ordirnary concrete. As a result, the elastic modulus was similar. On the other hand, polymer concrete for the compressive, tensile, and flexural strengths was quite more excellent. In particular, the measured tensile strength of polymer concrete was 4-10 times higher than that of ordirnary concrete. it was a big difference, and the frequency response function and damping ratio was studied through modal test and finite element analysis model. The dynamic stiffness of polymer concrete was 20% greater than that of ordirnary concrete, and the damping ratio of polymer concrete was approximately 3 times more than that of ordirnary concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.17-24
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• 2020

In this study, series of nonlinear seismic analysis were performed on a reinforced concrete intake tower surrounded by water. To consider the fluid effect around the structure, analysis models were composed using an added mass and CEL approach. At this time, the implicit method was used for the added mass model, and the explicit method was used for the fluid structure interaction model. The input motions were scaled to correspond to 500, 1000, and 2400 years return period of the same artificial earthquake. To estimate the counteractivity of the fluid coupled model, models without fluid effect were constructed and used as a reference. The material models of concrete and reinforcement were selected to consider the nonlinear behavior after yielding, and analysis were performed by ABAQUS. As results, in the acceleration response spectrum of the structure, it was found that the influence of the surrounding fluid reducing the peak frequency and magnitude corresponding to the fundamental frequency of the structure. However, the added mass model did not affect the peak value corresponding to the higher mode. The sectional moments were increased significantly in the case of the added mass model than those of the reference model. Especially, this amplification occurred largely for a small-sized earthquake response in which linear behavior is dominant. In the fluid structure interaction model, the sectional moment with a low frequency component amplifies compared to that of the reference model, but the sectional moment with a high requency component was not amplified. Based in these results, it was evaluated that the counteractivity of the additive mass model was greater than that of the fluid structure interaction model.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.245-259
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• 2022

Smart rural construction is an important direction for the Chinese government to promote the cause of "Rural Revitalization". In this paper, in the Xikou village project of the "future community" smart rural demonstration development project proposed by the local government of Zhejiang Province, China, the researcher participated in the design of the intellectualization of the smart rural life circle from the perspective of UX design and through qualitative and quantitative research methods. Through field investigation, understand the users' needs for intelligent design of smart countryside, and on this basis, design the maximum space of the region as a cognitive smart rural demonstration park, and quantitatively analyze the user experience feedback after the completion of the project. Before and after the actual design and application of the "Xikou village" in the demonstration area, chapters 3 and 4 are the symbols that can remember the rural era, the Rural Cultural Exchange Square. In the intelligent office space and living space, the user needs are composed of the design results. In order to reduce the anxiety of residents and tourists caused by the intelligent environment, the artificial manual service part is also designed. Now, as a case of intelligent rural space design, resident residence is developing continuously.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.2
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• pp.116-126
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• 2022

Although the 'Act on Urban Parks and Green Spaces' was revised in 2016 to provide a legal foundation for national urban parks, there was no further discussion or follow-up research for the implementation of national urban parks. This study investigates Korea's park and green space regulations and national urban park cases from across the world. It aims to analyze worldwide cases and set a course for a viable national urban park system in Korea. The importance and characteristics of national urban parks were evident after reviewing the cases of Japan, Sweden, Finland, and Canada, which have national urban park systems, and the United States and Germany, which aid city parks with national budgets. Each country determined the plans and procedures by assessing the scope of government intervention and the government's role. The importance of communication between the state and municipal governments and private sector participation and governance was recognized. A system was also formed in which local governments actively participate in the nomination, establishment, administration, and management of national urban parks. The results of this study are as follows. First, the concept of equitable national development should be implemented to activate the national urban park system. Second, the national urban park should be a land management tool that may be used to balance development and preservation. Third, a specific method of securing, constructing, administering, and operating national urban parks should be supplemented by the current legislative framework amendment. Furthermore, the establishment of a sustainable research institute is needed to comprehensively analyze parks and green space systems and make appropriate decisions.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.4
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• pp.341-353
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• 2022

Pipelines are buried in urban area, and the position (depth and orientation) of buried pipeline should be clearly identified before ground excavation. Although various geophysical methods can be used to detect the buried pipeline, it is not easy to identify the exact information of pipeline due to heterogeneous ground condition. Among various non-destructive geo-exploration methods, ground penetration radar (GPR) can explore the ground subsurface rapidly with relatively low cost compared to other exploration methods. However, the exploration data obtained from GPR requires considerable experiences because interpretation is not intuitive. Recently, researches on automated detection technology for GPR data using deep learning have been conducted. However, the lack of GPR data which is essential for training makes it difficult to build up the reliable detection model. To overcome this problem, we conducted a preliminary study to improve the performance of the detection model using finite difference time domain (FDTD)-based numerical analysis. Firstly, numerical analysis was performed with homogeneous soil media having single permittivity. In case of heterogeneous ground, numerical analysis was performed considering the ground heterogeneity using fractal technique. Secondly, deep learning was carried out using convolutional neural network. Detection Model-A is trained with data set obtained from homogeneous ground. And, detection Model-B is trained with data set obtained from homogeneous ground and heterogeneous ground. As a result, it is found that the detection Model-B which is trained including heterogeneous ground shows better performance than detection Model-A. It indicates the ground heterogeneity should be considered to increase the performance of automated detection model for GPR exploration.

• Journal of Korea Water Resources Association
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• v.54 no.spc1
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• pp.1183-1193
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• 2021

Low flow affects various fields such as river water supply management and planning, and irrigation water. A sufficient period of flow data is required to calculate the Flow Duration Curve. However, in order to calculate the Flow Duration Curve, it is essential to secure flow data for more than 30 years. However, in the case of rivers below the national river unit, there is no long-term flow data or there are observed data missing for a certain period in the middle, so there is a limit to calculating the Flow Duration Curve for each river. In the past, statistical-based methods such as Multiple Regression Analysis and ARIMA models were used to predict sulfur in the unmeasured watershed, but recently, the demand for machine learning and deep learning models is increasing. Therefore, in this study, we present the DNN technique, which is a machine learning technique that fits the latest paradigm. The DNN technique is a method that compensates for the shortcomings of the ANN technique, such as difficult to find optimal parameter values in the learning process and slow learning time. Therefore, in this study, the Flow Duration Curve applicable to the unmeasured watershed is calculated using the DNN model. First, the factors affecting the Flow Duration Curve were collected and statistically significant variables were selected through multicollinearity analysis between the factors, and input data were built into the machine learning model. The effectiveness of machine learning techniques was reviewed through statistical verification.

• Korean small business review
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• v.42 no.3
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• pp.145-172
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• 2020

This study shows that it is favorable for Korean companies to maintain fairness and authenticity trading relationship with trading companies. It suggests that a positive reputation can be secured, trust relationships can be built, and transaction costs can be reduced. For this purpose, research hypothesis was established, questionnaires were collected for domestic companies, and a hypothesis test was conducted. As a result of the research hypothesis test, the perception of transaction fairness and the perception of transaction authenticity have a positive effect on reputation, and the reputation has a positive effect on trust. Trust has a positive effect on the reduction of transaction costs, and reputation and trust play a role in the perception of transaction fairness and transaction authenticity and the reduction of transaction cost, and trust is a parameter between reputation and reduction in transaction cost. Do it. In order for sustainable management activities to be carried out for Korean companies, it is necessary to improve fairness and authenticity in business relations. It is important to have a positive reputation. It has been demonstrated that securing a positive reputation can develop into a trust relationship and ultimately lead to a decrease in transaction costs.

• Korean small business review
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• v.43 no.2
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• pp.1-30
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• 2021

This study is to analyze the relationship between supply chain resilience antecedent factors, supply chain resilience and business performance. Supply chain integration, risk management activity, and visibility were selected as the preceding factors of supply chain resilience, and the effect of these factors on agility and robustness as supply chain resilience, and the effects of agility and robustness factors on corporate management performance are studied. To this end, a survey was conducted on Korean manufacturing companies, and a total of 124 questionnaires were used for the study. As a result of the testing of the research hypothesis, supply chain integration, risk management activity, and visibility have a positive (+) significant effect on agility and robustness. In addition, agility had a positive (+) effect on corporate management performance. But robustness had a positive (+) effect on corporate management performance, but not significant. In order for manufacturing companies to secure supply chain resilience through such research hypothesis testing, it is necessary to secure supply chain integration, risk management activity, and visibility capabilities. It was confirmed that agility and visibility capability can be linked to corporate management performance. In addition, the overall relationship structure between the preceding factors of supply chain resilience, supply chain resilience, and business performance was presented.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.23-29
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• 2023

Microfluidic reactors have been made to achieve significant development for the generation of new functional materials to apply in a variety of fields. Over the last decade, microfluidic reactors have attracted attention as a user-friendly approach that is enabled to control physicochemical parameters such as size, shape, composition, and surface property. Here, we develop a centrifugal microfluidic reactor that can control the flow of fluid based on centrifugal force and generate multifunctional particles of various sizes and compositions. A centrifugal microfluidic reactor is fabricated by combining microneedles, micro- centrifuge tubes, and conical tubes, which are easily obtained in the laboratory. Depending on the experimental control param- eters, including centrifuge rotation speed, alginate concentration, calcium ion concentration, and distance from the needle to the calcium aqueous solution, this strategy not only enables the generation of size-controlled microparticles in a simple and reproducible manner but also achieves scalable production without the use of complicated skills or advanced equipment. Therefore, we believe that this simple strategy could serve as an on-demand platform for a wide range of industrial and academic applications, particularly for the development of advanced smart materials with new functionalities in biomedical engineering.