• Structural Engineering and Mechanics
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• v.77 no.2
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• pp.197-215
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• 2021

Under a severe environment of multiple hazards such as earthquakes and winds, the life-cycle performance of engineering structures may inevitably be deteriorated due to the fatigue effect caused by long-term exposure to wind loads, which would further increase the structural vulnerability to earthquakes. This paper presents a framework for evaluating the lifetime structural seismic performance under the effect of wind-induced fatigue considering different sources of uncertainties. The seismic behavior of a high-rise steel-concrete composite frame with buckling-restrained braces (FBRB) during its service life is systematically investigated using the proposed approach. Recorded field data for the wind hazard of Fuzhou, Fujian Province of China from Jan. 1, 1980 to Mar. 31, 2019 is collected, based on which the distribution of wind velocity is constructed by the Gumbel model after comparisons. The OpenSees platform is employed to establish the numerical model of the FBRB and conduct subsequent numerical computations. Allowed for the uncertainties caused by the wind generation and structural modeling, the final annual fatigue damage takes the average of 50 groups of simulations. The lifetime structural performance assessments, including static pushover analyses, nonlinear dynamic time history analyses and fragility analyses, are conducted on the time-dependent finite element (FE) models which are modified in lines with the material deterioration models. The results indicate that the structural performance tends to degrade over time under the effect of fatigue, while the influencing degree of fatigue varies with the duration time of fatigue process and seismic intensity. The impact of wind-induced fatigue on structural responses and fragilities are explicitly quantified and discussed in details.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.3
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• pp.159-175
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• 2021

Business ecosystem is becoming more inclined towards platform ecosystem, which attracts multi-side participants based on digital technology. The burgeoning interest in digital ecosystem leads to the rapid rise of research. In this paper, we suggest a research agenda, focusing on the benefits of complementors in platform ecosystem. First, we outline the extant papers on benefits from platform to participants from economic perspective, strategic management perspective, technology management perspective, and economic sociological perspective to provide comprehensive understanding about platform ecosystem. Second, we suggest systemic framework to provide integrative insights on the the topic of benefit from platform to complementors- (1) open innovation view, (2) economic performance view, and (3) sociological view. Specifically, we focus on empirical studies that investigate the relationship between the benefits from platform and spillover effects on complementors based on various dataset. In addition, by reviewing the past empirical research, we suggest future research agenda and implications for policy in platform ecosystem.

• Journal of the Korea Convergence Society
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• v.12 no.8
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• pp.93-104
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• 2021

In the process of the sustainable development of the world economy, the change and construction of urban living environment has always been the focus of people's attention. Therefore, the purpose of this study is to find out the potential safety hazards in residential areas, and put forward feasible improvement plans under the framework of CPTED theory.One is to collect the necessary literature. Secondly, according to the field investigation and questionnaire survey, sorting out the existing security risks. Finally, this paper puts forward the corresponding improvement and suggestion to this research. The conclusion is as follows: First, based on the six principles of CPTED theory, problems existing in Gamcheon Cultural Village, which is subject to research, were investigated. Second, six of the most serious safety issues (safety handle, landscaping, entrance control, signs, empty space, monitoring) were objectively analyzed, and designs were presented in terms of increasing safety stairs, installing automatic entrances, open access view, unifying signs, and building leisure areas.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.396-402
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• 2022

User interactions are being developed in various forms, and in particular, interactions using human gestures are being actively studied. Among them, hand gesture recognition is used as a human interface in the field of realistic media based on the 3D Hand Model. The use of interfaces based on hand gesture recognition helps users access media media more easily and conveniently. User interaction using hand gesture recognition should be able to view images by applying fast and accurate hand gesture recognition technology without restrictions on the computer environment. This paper developed a fast and accurate user hand gesture recognition algorithm using the open source media pipe framework and machine learning's k-NN (K-Nearest Neighbor). In addition, in order to minimize the restriction of the computer environment, a stereoscopic image control system based on user hand gesture recognition was designed and implemented using a web service environment capable of Internet service and a docker container, a virtual environment.

• Journal of Internet Computing and Services
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• v.23 no.3
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• pp.97-110
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• 2022

Federated learning is a learning method capable of performing model learning without transmitting learning data. The IoT or healthcare field is sensitive to information leakage as it deals with users' personal information, so a lot of attention should be paid to system design, but when using federated-learning, data does not move from devices where data is collected. Accordingly, many federated-learning implementations have been developed, but detailed research on system design for the development and operation of systems using federated learning is insufficient. This study shows that measures for the life cycle, code version management, model serving, and device monitoring of federated learning are needed to be applied to actual projects and distributed to IoT devices, and we propose a design for a development environment that complements these points. The system proposed in this paper considered uninterrupted model-serving and includes source code and model version management, device state monitoring, and server-client learning schedule management.

• Smart Structures and Systems
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• v.30 no.3
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• pp.221-237
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• 2022

This paper is concerned with nonlinear modeling and efficient numerical simulation of electrostrictive materials and structures. Two types of such materials are considered: relaxor ferroelectric ceramics and electrostrictive polymers. For ceramics, a geometrically linear formulation is developed, whereas polymers are studied in a geometrically nonlinear regime. In the paper, we focus on constitutive modeling first. For the reversible constitutive response under consideration, we introduce the augmented Helmholtz free energy, which is composed of a purely elastic part, a dielectric part and an augmentation term. For the elastic part, we involve an additive decomposition of the strain tensor into an elastic strain and an electrostrictive eigenstrain, which depends on the polarization of the material. In the geometrically nonlinear case, a corresponding multiplicative decomposition of the deformation gradient tensor replaces the additive strain decomposition used in the geometrically linear formulation. For the dielectric part, we first introduce the internal energy, to which a Legendre transformation is applied to compute the free energy. The augmentation term accounts for the contribution from vacuum to the energy. In our formulation, the augmented free energy depends not only on the strain and the electric field, but also on the polarization and an internal polarization; the latter two are internal variables. With the constitutive framework established, a Finite Element implementation is briefly discussed. We use high-order elements for the discretization of the independent variables, which include also the internal variables and, in case the material is assumed incompressible, the hydrostatic pressure, which is introduced as a Lagrange multiplier. The elements are implemented in the open source code Netgen/NGSolve. Finally, example problems are solved for both, relaxor ferroelectric ceramics and electrostrictive polymers. We focus on thin plate-type structures to show the efficiency of the numerical scheme and its applicability to thin electrostrictive structures.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.6
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• pp.1091-1102
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• 2022

Robotic systems have developed very rapidly over the past decade. Robot Operating System is an open source-based software framework for the efficient development of robot operating systems and applications, and is widely used in various research and industrial fields. ROS applications may contain various vulnerabilities. Various studies have been conducted to monitor the excution of these ROS applications at runtime. In this study, we propose a real-time attack detection system using event-based runtime monitoring in ROS 2. Our attack detection system extends tracetools of ros2_tracing to instrument events into core libraries of ROS 2 middleware layer and monitors the events during runtime to detect attacks on the application layer through out-of-order execution of the APIs.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.1009-1020
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• 1996

Direct-seeded rice can have comparable yield with transplanted rice if its inherent problems can be solved. It is a labor-saving technology and can significantly reduce production cost because seedling nursery , pulling , and transplanting are omitted. Turnaround time between cropping is reduced hence the possibility of a third annual crop. But direct-seeded rice is very vulnerable to pest attack (by birds, rats, and golden snails), desiccation, weed infestation, and prone to lodging resulting to unstable crop establishment and inconsistent yield. These problems can be solved by anaerobic seeding (sowing pre-germinated seeds under the soil). It requires precise seed placement into the soil to optimize its benefits. We developed a four-row anaerobic direct seeder (US $ 200 commercial price) for this purpose . It consist of a structural framework mounted with a drum -hopper metering device, flotation type drivewheels, spring-loaded and adjustable furrow closers, and furrow open rs, and a plastic rainguard. It can sow in line pre-germinated seeds into the soil thus permitting the use of mechanical weeders for a chemical-free weed control. Its performance was comparable with the Japanese two-row anaerobic seeder (costing US$400) in terms of seed placement and crop establishment. It was tested with five cultivars. Seeding rate varied from 38 kg/ha to 80kg/ha. Crop establishment ranged from 64 to 99 percent while grain yield varied from 3.0 t/ha to 5.4t/ha. A six-row anaerobic seeder was also developed and adapted to a powertiller for increased capacity , field efficiency , and easier operation. The anaerobic seeder is useful to farmers shifting to direct seeding to reduce rice production cost and to researchers conducting agronomic studies in direct-seeded rice. Blueprint of the machine is available free of charge from IRRI.

• Journal of Dental Anesthesia and Pain Medicine
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• v.22 no.2
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• pp.75-86
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• 2022

This review aims to identify the influence of the vehicle and its concentration used to carry calcium hydroxide (Ca(OH)₂) medicament on postoperative pain. The protocol for this review was registered in the open science framework (Registration DOI-10.17605/OSF.IO/4Y8A9) and followed the guidelines provided by the Joanna Briggs Institute. Reporting was based on the preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews (PRISMA-ScR). Literature screening and searches were performed on PubMed/Medline, Scopus, and EBSCO hosts. Furthermore, additional records were manually analyzed using various sources. The selected studies were published in English and included the use of any vehicle adjunct to Ca(OH)₂ to evaluate postoperative pain using qualitative and quantitative pain assessment tools. Descriptive analysis was conducted to review the study design, vehicle elements, and their effects. A preliminary search yielded 7584 studies, of which 10 were included. According to the data collected, the most commonly used Ca(OH)₂ vehicles were chlorhexidine (CHX), normal saline, and camphorated paramonochlorophenol/glycerine (CPMC/glycerine), which had a significant effect on postoperative pain. Among the included studies, six evaluated the effect of CHX as a vehicle. It was observed that a higher concentration of the vehicle (2%) showed a favorable response in reducing postoperative pain. A majority of studies have validated a positive consequence of using a vehicle on postoperative pain. Although higher vehicle concentrations were found to alter postoperative pain levels, the data were insufficient to draw a firm conclusion. Our scoping review indicates that further clinical studies should focus on using different vehicles at various concentrations and application times to check for feasible and safe exposure in addition to providing pain relief.

• Smart Media Journal
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• v.11 no.2
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• pp.70-76
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• 2022

IoT application development using a cloud server causes problems such as data transmission and reception delay, network traffic, and cost for real-time processing support in network connected hardware. To solve this problem, edge cloud-based platforms can use neuromorphic hardware to enable fast data transfer. In this paper, we propose a model optimization method for supporting spiking neural networks on FPGA hardware. We focused on auto-adjusting network model parameters optimized for neuromorphic hardware. The proposed method performs optimization to show higher performance based on user requirements for accuracy. As a result of performance analysis, it satisfies all requirements of accuracy and showed higher performance in terms of expected execution time, unlike the naive method supported by the existing open source framework.