• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.597-603
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• 2006

The purpose of this study is to improve the short term rainfall forecast skill using neural network model that can deal with the non-linear behavior between satellite data and ground observation, and minimize the flood damage. To overcome the geographical limitation of Korean peninsula and get the long forecast lead time of 3 to 6 hour, the developed rainfall forecast model took satellite imageries and wide range AWS data. The architecture of neural network model is a multi-layer neural network which consists of one input layer, one hidden layer, and one output layer. Neural network is trained using a momentum back propagation algorithm. Flood was estimated using rainfall forecasts. We developed a dynamic flood inundation model which is associated with 1-dimensional flood routing model. Therefore the model can forecast flood aspect in a protected lowland by levee failure of river. In the case of multiple levee breaks at main stream and tributaries, the developed flood inundation model can estimate flood level in a river and inundation level and area in a protected lowland simultaneously.

• Steel and Composite Structures
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• v.49 no.1
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• pp.81-89
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• 2023

A simplified calculation method of natural vibration characteristics of high-speed railway multi-span bridge-longitudinal ballastless track system is proposed. The rail, track slab, base slab, main beam, bearing, pier, cap and pile foundation are taken into account, and the multi-span longitudinal ballastless track-beam-bearing-pier-cap-pile foundation integrated model (MBTIM) is established. The energy equation of each component of the MBTIM based on Timoshenko beam theory is constructed. Using the improved Fourier series, and the Rayleigh-Ritz method and Hamilton principle are combined to obtain the extremum of the total energy function. The simplified calculation formula of the natural vibration frequency of the MBTIM under the influence of vertical and longitudinal vibration is derived and verified by numerical methods. The influence law of the natural vibration frequency of the MBTIM is analyzed considering and not considering the participation of each component of the MBTIM, the damage of the track interlayer component and the stiffness change of each layer component. The results show that the error between the calculation results of the formula and the numerical method in this paper is less than 3%, which verifies the correctness of the method in this paper. The high-order frequency of the MBTIM is significantly affected considering the track, bridge pier, pile soil and pile cap, while considering the influence of pile cap on the low-order and high-order frequency of the MBTIM is large. The influence of component damage such as void beneath slab, mortar debonding and fastener failure on each order frequency of the MBTIM is basically the same, and the influence of component damage less than 10m on the first fourteen order frequency of the MBTIM is small. The bending stiffness of track slab and rail has no obvious influence on the natural frequency of the MBTIM, and the bending stiffness of main beam has influence on the natural frequency of the MBTIM. The bending stiffness of pier and base slab only has obvious influence on the high-order frequency of the MBTIM. The natural vibration characteristics of the MBTIM play an important guiding role in the safety analysis of high-speed train running, the damage detection of track-bridge structure and the seismic design of railway bridge.

• Journal of Ginseng Research
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• v.47 no.6
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• pp.743-754
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• 2023

Background: Myocardial fibrosis post-myocardial infarction (MI) can induce maladaptive cardiac remodeling as well as heart failure. Although 20(S)-ginsenoside Rg3 (Rg3) has been applied to cardiovascular diseases, its efficacy and specific molecular mechanism in myocardial fibrosis are largely unknown. Herein, we aimed to explore whether TGFBR1 signaling was involved in Rg3's anti-fibrotic effect post-MI. Methods: Left anterior descending (LAD) coronary artery ligation-induced MI mice and TGF-β1-stimulated primary cardiac fibroblasts (CFs) were adopted. Echocardiography, hematoxlin-eosin and Masson staining, Western-blot and immunohistochemistry, CCK8 and Edu were used to study the effects of Rg3 on myocardial fibrosis and TGFBR1 signaling. The combination mechanism of Rg3 and TGFBR1 was explored by surface plasmon resonance imaging (SPRi). Moreover, myocardial Tgfbr1-deficient mice and TGFBR1 adenovirus were adopted to confirm the pharmacological mechanism of Rg3. Results: In vivo experiments, Rg3 ameliorated myocardial fibrosis and hypertrophy and enhanced cardiac function. Rg3-TGFBR1 had the 1.78×10^-7 M equilibrium dissociation constant based on SPRi analysis, and Rg3 inhibited the activation of TGFBR1/Smads signaling dose-dependently. Cardiac-specific Tgfbr1 knockdown abolished Rg3's protection against myocardial fibrosis post-MI. In addition, Rg3 downregulated the TGF-β1-mediated CFs growth together with collagen production in vitro through TGFBR1 signaling. Moreover, TGFBR1 adenovirus partially blocked the inhibitory effect of Rg3. Conclusion: Rg3 improves myocardial fibrosis and cardiac function through suppressing CFs proliferation along with collagen deposition by inactivation of TGFBR1 pathway.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.709-719
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• 2023

In general, most of the electrical equipment responsible for control within power plants is housed in self-standing cabinets. These cabinets are typically fixed to a slab using post-installed anchors. Although the fixation method of using post-installed anchors provides stability, there is a risk of conductor failure due to external forces, including moments. However, the performance assessment of current anchors is only evaluated through uniaxial material tests. Therefore, the primary purpose of this study is to compare the static performance of post-installed anchors, considering on-site installation conditions, with their performance in material tests and to analyze the behavioral characteristics of the anchors. While conducting experiments using actual cabinets would be ideal, practical and spatial constraints make this approach difficult. As an alternative, experiments were conducted using a test specimen consisting of a steel column and a support. As a result, the pull-out performance of anchors reflecting on-site installation conditions was measured to be about 10% higher than that observed in material tests. The trends in load reduction and the point of maximum performance for the anchors also differed. To verify the reliability of the experimental study, a 3D FEM analysis was performed, which will provide predictive information on the loads transferred to the post-installed anchors for structural performance evaluations of electrical cabinets using shaking table test in the future.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.9
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• pp.263-272
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• 2023

Industrial Internet of Things (IIoT) is an important factor in increasing production efficiency in industrial sectors, along with data collection, exchange and analysis through large-scale connectivity. However, as traffic increases explosively due to the recent spread of IIoT, an allocation method that can efficiently process traffic is required. In this thesis, I propose a two-stage task offloading decision method to increase successful task throughput in an IIoT environment. In addition, I consider a hybrid offloading system that can offload compute-intensive tasks to a mobile edge computing server via a cellular link or to a nearby IIoT device via a Device to Device (D2D) link. The first stage is to design an incentive mechanism to prevent devices participating in task offloading from acting selfishly and giving difficulties in improving task throughput. Among the mechanism design, McAfee's mechanism is used to control the selfish behavior of the devices that process the task and to increase the overall system throughput. After that, in stage 2, I propose a multi-armed bandit (MAB)-based task offloading decision method in a non-stationary environment by considering the irregular movement of the IIoT device. Experimental results show that the proposed method can obtain better performance in terms of overall system throughput, communication failure rate and regret compared to other existing methods.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.5
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• pp.95-104
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• 2022

This study aims to find out the influence of the intolerance of uncertainty on entrepreneurial intention by focusing on the start-up support system awareness. While most of existing studies focused on the positive psychological variables and individual environmental characteristics influencing on the entrepreneurial intention, this study has taken a look at the influence of the intolerance of uncertainty as the psychological variable to the entrepreneurial intention to negatively act on the entrepreneurial intention. As a result of the analysis, the intolerance of uncertainty under the control of entrepreneurship and gender is shown to have the negative (-) influence on the entrepreneurial intention and has high level of recognition on the start-up support system perception, and the start-up support system perception is confirmed to have positive (+) influence on the entrepreneurial intention. And, it also indicates that, with respect to the influence of the intolerance of uncertainty on the entrepreneurial intention, the start-up support system perception has the partial medium effect. Following this result of the study, it provides following indications: First the existing studies on the entrepreneurial intention had not covered the intolerance of uncertainty but it is confirmed as the psychological variable with negative influence on the entrepreneurial intention. Second, it is feasible for the preliminary start-up businesses may turn the fear on start-up failure into positive entrepreneurial intention with the start-up support system perception as the leading vehicle. And, third, based on the result, the government should enhance the start-up support system perception even more by seeking ways of efficient publicity to enable more preliminary start-up businesses to participate in diverse start-up support policies. Lastly, it discusses the limitations of this study as well as proposal for ensuing study plans.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.1-8
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• 2024

The expansion joint is installed to offset the expansion of the superstructure and must ensure sufficient gap during its service life. In detailed guideline of safety inspection and precise safety diagnosis for bridge, damage due to lack or excessive gap is specified, but there are insufficient standards for determining the abnormal behavior of superstructures. In this study, a data-based maintenance was proposed by continuously monitoring the expansion-gap data of the same expansion joint. A total of 2,756 data were collected from 689 expansion joint, taking into account the effects of season. We have developed a method to evaluate changes in the expansion joint-gap that can analyze the thermal movement through four or more data at the same location, and classified the factors that affect the superstructure behavior and analyze the influence of each factor through deep learning and explainable artificial intelligence(AI). Abnormal behavior of the superstructure was classified into narrowing and functional failure through the expansion joint-gap evaluation graph. The influence factor analysis using deep learning and explainable AI is considered to be reliable because the results can be explained by the existing expansion gap calculation formula and bridge design.

• Journal of the Korean Society for Library and Information Science
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• v.58 no.1
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• pp.99-122
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• 2024

This study investigated librarians' awareness of and demand for the librarian learning community in order to successfully introduce and operate the librarian learning community. For this purpose, an online survey was conducted targeting current librarians and a total of 474 responses were collected. The main analysis results are as follows. Firstly, librarians showed a very low awareness of the librarian learning community, while they highly evaluated the purpose and significance of such a community. Secondly, the motivations for librarians to participate in the librarian learning community were primarily focused on professional growth, solidarity with colleagues, and satisfaction of intellectual curiosity, in that order. Thirdly, the ultimate values of the librarian learning community were identified as improving library services, enhancing professionalism, fostering collaborative group exploration, sharing values and visions. Fourthly, the success factors of the librarian-learning community were ranked as follows: member voluntarism, a culture of collaboration among members, dedicated time (once a week), and a supportive environment (budget, space, etc.). On the other hand, the failure factors were identified as a lack of time due to heavy workloads, lack of member voluntarism, indifference from superiors, and insufficient support environment (budget, space, etc.). Finally, the willingness to participate is also very high. Furthermore, it was observed that there is a wide range of interests in various topics among librarians. The results of this study are expected to be useful as basic data for determining practical operation methods or selecting topics when operating a librarian learning community in the future.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.6
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• pp.71-86
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• 2023

Although starting a business plays a key role in strengthening national competitiveness and creating jobs, it is recognized as a risky choice. Failure to start a business can result in a wide range of negative effects, such as loss of personal wealth as well as deterioration of national competitiveness. This study considers startups that have reached a level of sustainable growth by achieving performance above the minimum profitability and sales standards for KOSDAQ listing, or achieved EXIT through sale or listing, as successful startups. based on the practical experiences of 23 successful entrepreneurs and Based on perception, the importance and priorities of startup success factors were derived through stratification analysis (Analytic Hierarchy Process, AHP), and interviews were conducted. In particular, using the ERIS model, we comprehensively analyze various variables of a start-up by considering the four elements of the entrepreneur, resources, industry, and strategy, and examine the changes and importance of success factors according to the characteristics of each growth stage of the start-up. As a goal, we specifically identified the challenges and opportunities faced by entrepreneurs at each stage. As a result of the study, the order of importance of the top factors of success factors in the start-up period was found to be the entrepreneur, resources, industry, and strategy. In particular, the importance of the entrepreneur's entrepreneurship spirit, special capabilities, general capabilities, and human resources was emphasized. The order of importance of the top factors of success factors during the growth period was found in the following order: entrepreneur, resources, industry, and strategy. In particular, the importance of general capabilities, entrepreneurship, and human and organizational resources was emphasized. This study is significant in that it analyzes startup success factors from the perspective of successful entrepreneurs and provides useful insights and directions to entrepreneurs and policy makers.

• Journal of Cardiovascular Imaging
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• v.31 no.2
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• pp.85-95
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• 2023

BACKGROUND: The prognostic utility of follow-up transthoracic echocardiography (FU-TTE) in patients with hypertrophic cardiomyopathy (HCM) is unclear, specifically in terms of whether changes in echocardiographic parameters in routine FU-TTE parameters are associated with cardiovascular outcomes. METHODS: From 2010 to 2017, 162 patients with HCM were retrospectively enrolled in this study. Using echocardiography, HCM was diagnosed based on morphological criteria. Patients with other diseases that cause cardiac hypertrophy were excluded. TTE parameters at baseline and FU were analyzed. FU-TTE was designated as the last recorded value in patients who did not develop any cardiovascular event or the latest exam before event development. Clinical outcomes were acute heart failure, cardiac death, arrhythmia, ischemic stroke, and cardiogenic syncope. RESULTS: Median interval between the baseline TTE and FU-TTE was 3.3 years. Median clinical FU duration was 4.7 years. Septal trans-mitral velocity/mitral annular tissue Doppler velocity (E/e'), tricuspid regurgitation velocity, left ventricular ejection fraction (LVEF), and left atrial volume index (LAVI) at baseline were recorded. LVEF, LAVI, and E/e' values were associated with poor outcomes. However, no delta values predicted HCM-related cardiovascular outcomes. Logistic regression models incorporating changes in TTE parameters had no significant findings. Baseline LAVI was the best predictor of a poor prognosis. In survival analysis, an already enlarged or increased size LAVI was associated with poorer clinical outcomes. CONCLUSIONS: Changes in echocardiographic parameters extracted from TTE did not assist in predicting clinical outcomes. Cross-sectionally evaluated TTE parameters were superior to changes in TTE parameters between baseline and FU at predicting cardiovascular events.