• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.141-141
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• 2022

Drought is a global phenomenon that affects almost all landscapes and causes major damages. Due to non-linear nature of contributing factors, drought occurrence and its severity is characterized as stochastic in nature. Early warning of impending drought can aid in the development of drought mitigation strategies and measures. Thus, drought forecasting is crucial in the planning and management of water resource systems. The primary objective of this study is to make improvement is existing drought forecasting techniques. Therefore, we proposed an improved version of Seasonal Autoregressive Integrated Moving Average (SARIMA) model (MD-SARIMA) for reliable drought forecasting with three years lead time. In this study, we selected four watersheds of Han River basin in South Korea to validate the performance of MD-SARIMA model. The meteorological data from 8 rain gauge stations were collected for the period 1973-2016 and converted into watershed scale using Thiessen's polygon method. The Standardized Precipitation Index (SPI) was employed to represent the meteorological drought at seasonal (3-month) time scale. The performance of MD-SARIMA model was compared with existing models such as Seasonal Naive Bayes (SNB) model, Exponential Smoothing (ES) model, Trigonometric seasonality, Box-Cox transformation, ARMA errors, Trend and Seasonal components (TBATS) model, and SARIMA model. The results showed that all the models were able to forecast drought, but the performance of MD-SARIMA was robust then other statistical models with Wilmott Index (WI) = 0.86, Mean Absolute Error (MAE) = 0.66, and Root mean square error (RMSE) = 0.80 for 36 months lead time forecast. The outcomes of this study indicated that the MD-SARIMA model can be utilized for drought forecasting.

• Structural Engineering and Mechanics
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• v.84 no.4
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• pp.489-502
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• 2022

This paper is aimed at developing an optimization-based Finite Element model updating approach for structural damage identification and quantification. A modal flexibility-based error function is introduced, which uses modal assurance criterion to formulate the updating problem as an optimization problem. Because of the inexplicit input/output relationship between the candidate solutions and the error function's output, a robust and efficient optimization algorithm should be employed to evaluate the solution domain and find the global extremum with high speed and accuracy. This paper proposes a new multi-stage Selective Particle Swarm Optimization (SPSO) algorithm to solve the optimization problem. The proposed multi-stage strategy not only fixes the premature convergence of the original Particle Swarm Optimization (PSO) algorithm, but also increases the speed of the search stage and reduces the corresponding computational costs, without changing or adding extra terms to the algorithm's formulation. Solving the introduced objective function with the proposed multi-stage SPSO leads to a smart feedback-wise and self-adjusting damage detection method, which can effectively assess the health of the structural systems. The performance and precision of the proposed method are verified and benchmarked against the original PSO and some of its most popular variants, including SPSO, DPSO, APSO, and MSPSO. For this purpose, two numerical examples of complex civil engineering structures under different damage patterns are studied. Comparative studies are also carried out to evaluate the performance of the proposed method in the presence of measurement errors. Moreover, the robustness and accuracy of the method are validated by assessing the health of a six-story shear-type building structure tested on a shake table. The obtained results introduced the proposed method as an effective and robust damage detection method even if the first few vibration modes are utilized to form the objective function.

• International conference on construction engineering and project management
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• 2020.12a
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• pp.425-432
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• 2020

In order to improve the sustainability and smart construction, it is discussed arguably that developing and applying consistent "standard model" to plan business, design, construct and operate a building is considered to be one of the effective and efficient approach. The scope of this article is to examine, from the international developer's perspective, the "standard model" approach of a hotel brand to building projects in the UK, and also to explore potential role of project team to mitigate any local difference at the project level. These projects are developed by the same developer adopting the same business plan, design and operation to each project. In order to clarify the actual and likely difference in construction results, reference is also made to those building projects located in other geographical markets including Japan, Germany and USA, and focus is given on the analysis of its programme and cost. Principle findings are that there exists geographical difference especially in environmental and planning system, and that major local difference is found at least in the programme at the design stage. In contrast, the difference in the building cost itself may not be necessarily considered major if currency exchange rate being taken into account appropriately. It is also observed that there were cases where any difference in the programme was mitigated by taking different approach to procuring and defining roles of management and professional team at the project level. In conclusion, from the international developer's perspective, the geographical difference of the "construction system" surrounding building projects can typically lead to major prolongation of programme, however, these different construction results could be mitigated at least to a certain extent by introducing appropriate changes to the role of project team.

• Smart Structures and Systems
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• v.30 no.5
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• pp.479-500
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• 2022

In this study, a new type of isolation bearing is proposed by combining S-shaped steel plate dampers (SSDs) with a spherical steel bearing, and the seismic control effect of a five-span standard high-speed railway bridge is investigated. The advantages of the proposed S-shaped steel damping friction bearing (SSDFB) are that it cannot only lengthen the structural periods, dissipate the seismic energy, but also prevent bridge unseating due to the restraint effectiveness of SSDs in the large relative displacements between the girders and piers. This study first presents a detailed description and working principle of the SSDFB. Then, mechanical modeling of the SSDFB was derived to fundamentally define its cyclic behavior and obtain key mechanical parameters. The numerical model of the SSDFB's critical component SSD was verified by comparing it with the experimental results. After that, parameter studies of the dimensions and number of SSDs, the friction coefficient, and the gap length of the SSDFBs were conducted. Finally, the longitudinal seismic responses of the bridge with SSDFBs were compared with the bridge with spherical bearing and spherical bearing with strengthened shear keys. The results showed that the SSDFB can not only significantly mitigate the shear force responses and residual displacement in bridge substructures but also can effectively reduce girder displacement and prevent bridge unseating, at a cost of inelastic deformation of the SSDs, which is easy to replace. In conclusion, the SSDFB is expected to be a cost-effective option with both multi-stage energy dissipation and restraint capacity, making it particularly suitable for seismic isolation application to high-speed railway bridges.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.143-143
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• 2022

Plant defense systems against pathogens have been studied extensively and are currently a hot topic in plant science. Using a reverse genetics technique, this study looked into the involvement of the NO-downregulated NAD(P)-binding Rossmann-fold superfamily gene in plant growth and defense in Arabidopsis thaliana. For this purpose, the knockout and overexpressing plant of the candidate gene along with the relevant controls were exposed to control, oxidative and nitro-oxidative stresses. The results showed that candidate gene negatively regulates plants' root and shoot lengths. To investigate the role of the candidate gene in plant basal defense, R-gene-mediated resistance and systemic acquired resistance (SAR) plants were challenged with virulent or avirulent strains of Pseudomonas syringae pathovar tomato (Psf) DC3000. The results showed that the candidate gene negatively regulates plants' basal defense, R-gene-mediated resistance and SAR. Further characterization via GO analysis associated the candidate gene with metabolic and cellular processes and response to light stimulus, nucleotide binding and cellular location in the cytosol and nucleus. Protein structure analysis indicated the presence of a canonical Oxidoreductase family NAD (P)-binding Rossmann fold domain of 120 amino acids with a total of 121 plant homologs across 35 different plant species in the clad streptophyta. Arabidopsis eFP browser showed its expression in almost all the above-ground parts. Protein analysis indicated C225 and C359 as potential targets for S-Nitrosylation by NO. SMART analysis indicated possible interactions with mevalonate/galactokinase, galacturonic acid kinase, arabinose kinase, putative xylulose kinase, GroES-like zinc-binding alcohol dehydrogenase and various glyceraldehyde-3-phosphate dehydrogenases.

• Journal of the Economic Geographical Society of Korea
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• v.26 no.2
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• pp.155-168
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• 2023

Health geography has gained importance due to healthy smart cities, regions, and the integration of geo-internet and blockchain technologies. This study explores the intersection of geography and health, focusing on specific health challenges faced by individuals and groups. Using observational and descriptive methods, the study takes a regional approach to illuminate the socio-economic factors that are critical to addressing global health challenges. Drawing on academic literature and practical research, a concise case study of health challenges in Uzbekistan is presented, offering valuable insights. The analysis of data from informative articles and UN publications highlights the interdisciplinary nature of health geography and its practical applicability for researchers and policymakers. The findings underscore the important role of geography and health sciences in addressing region-specific diseases while highlighting the importance of spatial analysis in understanding environmental hazards and health impacts, including disease outbreaks.

• Smart Structures and Systems
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• v.32 no.6
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• pp.349-358
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• 2023

Real-Time Hybrid Testing (RTHT) requires the numerical substructure calculations to be completed within the defined integration time interval due to its real-time loading demands. For solving the problem, A Real-Time Hybrid Testing based on Restart-Loading Technology (RTHT-RLT) is proposed in this paper. In the proposed method, in case of the numerical substructure calculations cannot be completed within the defined integration time interval, the experimental substructure was returned back to the initial state statically. When the newest loading commands were calculated by the numerical substructure, the experimental substructure was restarted loading from the initial state to the newest loading commands so as to precisely disclosing the dynamic performance of the experimental substructure. Firstly, the methodology of the RTHT-RLT is proposed. Furthermore, the numerical simulations and experimental tests on one frame structure with a viscous damper are conducted for evaluating the feasibility and effectiveness of the proposed RTHT-RLT. It is shown that the proposed RTHT-RLT innovatively renders the nonreal-time refined calculation of the numerical substructure feasible for the RTHT. The numerical and experimental results show that the proposed RTHT-RLT exhibits excellent performance in terms of stability and accuracy. The proposed RTHT-RLT may have broad application prospects for precisely investigating the dynamic behavior of large and complex engineering structures with specific experimental substructure where a restarting procedure does not affect the relevant hysteretic response.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.810-817
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• 2023

Oysters are a highly consumed seafood throughout Korea, but they have a short shelf life because they support rapid microbial growth due to their of high moisture content and fragile muscle tissue. We examined natural food additives including lactic acid bacteria fermentation powder, rosemary extract, and lemon juice for their ability to preserve raw oyster Crassostrea gigas quality. Samples were stored at 4℃, and microbiological and physicochemical analyses were conducted. Among the natural additives tested, lemon juice was the most effective. Lemon juice was thus applied at different concentrations (50-300 ppm) to quantitatively assess its effect on total viable cell count, pH, glycogen, soluble protein, and turbidity. 200 ppm was confirmed to be optimal, and is projected to extend shelf life by 2 days compared to the control group.

• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.844-850
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• 2023

Purpose: This paper is about the development of a short-circuit protection power supply device using incandescent bulbs and its application for educational materials. This article, which considers electrical safety and energy conservation at the same time, has many kinds of potential applications for both educational and industrial areas. The above mentioned short-circuit protection power supply device using incandescent bulbs enhances safety and efficiency compared to normal current power supply devices. Additionally, as an educational materials, it can be used for electric safety training, and provides practical electrical safety knowledge on our actual life. Method: Using incandescent bulbs, design new type of short-circuit protection power supply device, and through verifying the function and safety of the device, make new type device, and applying it for an educational tool. Conclusion: This study is to develop new type of power supply device, and verify the possibility of the application for the device as an educational materials. Through this research, show an innovative solution, which contribute to electrical safety and energy conservation, and open the potential possibility on educational and industrial sectors.This kind of research is expected to contributes to enhanced research, and education on electrical safety and energy conservation management.

• Composites Research
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• v.36 no.5
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• pp.342-348
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• 2023

There has been increasing demand for real-time monitoring of body and ambient temperatures using wearable devices. Graphene-based thermistors have been developed for high-performance flexible temperature sensors. In this study, the temperature coefficient of resistance (TCR) of monolayer graphene was controlled by coating polyethylenimine (PEI) on graphene surfaces to enhance its temperature-sensing performances. Monolayer graphene grown by chemical vapor deposition (CVD) was wet-transferred onto a target substrate. To facilitate the interfacial doping by PEI, the hydrophobic graphene surface was altered to be hydrophilic by oxygen plasma treatments while minimizing defect generation. The effect of PEI doping on graphene was confirmed using a back-gated field-effect transistor (FET). The CVD-grown monolayer graphene coated with PEI exhibited an improved TCR of -0.49(±0.03) %/K in a temperature range of 30~50℃.