• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.411-419
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• 2020

The experiment of unsteady rip current generated at the successive ends of breaking wave crests of honeycomb pattern waves was conducted in a laboratory wave basin, and its time-varying evolution was observed by using ortho-rectified images. The present experiment utilized the generation of a quasi nodal line of the honeycomb-pattern waves formed by out-of-phase motion of two piston-type wavemakers arranged in the transverse direction, instead of the original honeycomb pattern waves which are generated when two wave trains propagate with slightly different wave directions. The velocities of rip current were measured by using the LSPIV (Large-Scale Particle Image Velocimetry) technique. As a result, the unsteady rip current was generated between successive ends of wave crests, and evolved with its shear fluctuations in this experiment. Also, the time series of LSPIV velocity of the unsteady rip current showd its short component due to waves and its long component due to wave-induced currents.

• Smart Structures and Systems
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• v.28 no.6
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• pp.745-760
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• 2021

Dynamic buckling of structure is one of the failure modes that needs to be considered since it may result in catastrophic failure of the structure in a short period of time. For a thin fiber-reinforced polymer (FRP) plate under compression, buckling is an inherent hazard which will be intensified by the existence of defects like holes, cracks, and delamination. On the other hand, the growth of the delamination is another prime concern for thin FRP plates. In the current paper, reinforcing the plates against buckling is realized by using SMA wires in the form of stitches. A numerical framework is proposed to simulate the dynamic instability emphasizing the effect of the SMA stitches in suppressing delamination growth. The suggested algorithm is more accurate than the other methods when considering the transformation point of the SMA wires and the modeling of the cohesive zone using simple and yet reliable technique. The computational design of the method by producing the line by line orders leads to a simple algorithm for simulating the super-elastic behavior. The Lagoudas constitutive model of the SMA material is implemented in the form of user material subroutines (VUMAT). The normal bilinear spring model is used to reproduce the cohesive zone behavior. The nonlinear finite element formulation is programmed into FORTRAN using the Newmark-beta numerical time-integration approach. The obtained results are compared with the results obtained by the finite element method using ABAQUS/Explicit solver. The obtained results by the proposed algorithm and those by ABAQUS are in good agreement.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.4
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• pp.699-707
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• 2023

DevSecOps is a concept that adds security procedures to the operational procedures of DevOps to respond to the short development and operation cycle. Multi-step vulnerability scanning process should be considered to provide reliable security while supporting rapid development and deployment cycle in DevSecOps. Many open-source vulnerability scanning tools available can be used for each stage of scanning, but there are difficulties in evaluating the security level and identifying the importance of information in integrated operation due to the various functions supported by the tools and different security results. This paper proposes an integrated security metric design plan for scurity results and the combination of open-source scanning tools that can be used in security stage when building the open-source based DevSecOps system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.4
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• pp.1147-1161
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• 2023

The Internet of Things (IoT) requires a new processing model that will allow scalability in cloud computing while reducing time delay caused by data transmission within a network. Such a model can be achieved by using resources that are closer to the user, i.e., by relying on edge computing (EC). The amount of IoT data also grows with an increase in the number of IoT devices. However, building such a flexible model within a heterogeneous environment is difficult in terms of resources. Moreover, the increasing demand for IoT services necessitates shortening time delay and response time by achieving effective load balancing. IoT devices are expected to generate huge amounts of data within a short amount of time. They will be dynamically deployed, and IoT services will be provided to EC devices or cloud servers to minimize resource costs while meeting the latency and quality of service (QoS) constraints of IoT applications when IoT devices are at the endpoint. EC is an emerging solution to the data processing problem in IoT. In this study, we improve the load balancing process and distribute resources fairly to tasks, which, in turn, will improve QoS in cloud and reduce processing time, and consequently, response time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6B
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• pp.743-750
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• 2008

Due to unusual climate change and global warming, drought and flood happen frequently not only in Korea but also in all over the world. It leads to the serious damages and injuries in urban areas as well as rural areas. Since the concentration time is short and the flood flows increase urgently in urban stream basin, the chances of damages become large once heavy storm occurs. A decision support system for flood forecasting and warning in urban stream is developed as an alternative to alleviate the damages from heavy storm. It consists of model base management system based on ANFIS (Adaptive Neuro Fuzzy Inference System), database management system with real time data building capability and user friendly dialog generation and management system. Applying the system to the Tanceon river basin, it can forecast and warn the stream flows from the heavy storm in real time and alleviate the damages.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.375-383
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• 2006

Nationals Assembly have experiencing unbalance between capacities and demand of parking facilities because of increasing parking demand, free parking policy, long term parking and passenger car use of workers, usage of neighborhood office workers and visitors. The lack of parking facilities cause illegal parking on the street inside and outside of National Assembly which result in the disorder of parking culture. To solve these parking problems, this study suggest parking management system to enter the National Assembly for the short term and charging parking fee, operation by private company, constructing parking building by abrogation of upper limit and construction of ground park, and so on. The study, also, suggested to strengthen weekday or 10 day shift system, to increase shuttle bus and commuting bus, to activation of Han River waterside parking area, public transportation with those new parking management system. For the conclusion, the parking problems of National Assembly should be focused more on parking management than the parking facilities supply.

• Korean Journal of Social Welfare Studies
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• v.41 no.1
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• pp.203-226
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• 2010

Using the Korean Welfare Panel Study, this study examines the labor-market activities of uninsured persons and discusses policy implications for reforming the National Pension Scheme in Korea. First, despite the short observation period, the data show that pension status is not a static state and can be better understood in terms of dynamic processes. Second, in addition to frequent changes in income-earning activities, complex criteria for pension coverage cause substantial transitions in pension status. Third, a portion of uninsured persons involve in income-earning activities but they tend to face poor working conditions as well as unstable employment. Overall, this study suggests that building solid foundations for developing a financially sustainable and reliable social protection system is more important than rapid increase in pension coverage.

• Journal of the Korean Electrochemical Society
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• v.27 no.2
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• pp.55-72
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• 2024

Secondary batteries are used as an essential renewable energy source in our lives, such as electric vehicles and energy storage systems (ESS), as an alternative to fossil fuels due to global warming. However, cases of battery fires and explosions have been reported due to thermal runaway in secondary batteries due to various causes such as overdischarge, high-speed charging and discharging, and external short circuit, and great efforts are being made to find solutions suitable for each cause. In particular, as cases presumed to be caused by the overcharging process have been reported, this review will examine the chemical reactions of secondary batteries that can occur during the overcharging process and discuss risk investigation methods to check and prevent them.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1159-1172
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• 2020

This study applied deep convolution neural network based on U-Net and SegNet using long period weather radar data to very short-term rainfall prediction. And the results were compared and evaluated with the translation model. For training and validation of deep neural network, Mt. Gwanak and Mt. Gwangdeoksan radar data were collected from 2010 to 2016 and converted to a gray-scale image file in an HDF5 format with a 1km spatial resolution. The deep neural network model was trained to predict precipitation after 10 minutes by using the four consecutive radar image data, and the recursive method of repeating forecasts was applied to carry out lead time 60 minutes with the pretrained deep neural network model. To evaluate the performance of deep neural network prediction model, 24 rain cases in 2017 were forecast for rainfall up to 60 minutes in advance. As a result of evaluating the predicted performance by calculating the mean absolute error (MAE) and critical success index (CSI) at the threshold of 0.1, 1, and 5 mm/hr, the deep neural network model showed better performance in the case of rainfall threshold of 0.1, 1 mm/hr in terms of MAE, and showed better performance than the translation model for lead time 50 minutes in terms of CSI. In particular, although the deep neural network prediction model performed generally better than the translation model for weak rainfall of 5 mm/hr or less, the deep neural network prediction model had limitations in predicting distinct precipitation characteristics of high intensity as a result of the evaluation of threshold of 5 mm/hr. The longer lead time, the spatial smoothness increase with lead time thereby reducing the accuracy of rainfall prediction The translation model turned out to be superior in predicting the exceedance of higher intensity thresholds (> 5 mm/hr) because it preserves distinct precipitation characteristics, but the rainfall position tends to shift incorrectly. This study are expected to be helpful for the improvement of radar rainfall prediction model using deep neural networks in the future. In addition, the massive weather radar data established in this study will be provided through open repositories for future use in subsequent studies.

• Journal of Popular Narrative
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• v.27 no.3
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• pp.195-228
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• 2021

The purpose of this study is to review the mobility-based textual research methods raised in Mobility and Foucault and apply them to textual analysis. This book contains seven articles applying Foucault's terms to mobility studies, giving intellectual stimulation to both studies. Since Foucault examined discipline power operated through the technology of distinguishing between rational/irrational and normal/abnormal, his works seem to a study of closed spaces like prisons. However, the authors of this book note that Foucault's works already had sufficient insight on mobility, and them actively incorporated it into mobility study. When we concentrate Foucault's works on mobility as a governmentality and a dispositif, the tension and dynamics between mobility and immobility are emphasized. And then it is possible to cross the simple dichotomy in mobility studies. This paper analyzes Kim Joong-hyuk's short story 1F/B1 by applying this method. This story describes a building manager who seems to be fixed in a building, but the mobility of him in the story goes through stereotypes and creates new spaces. Kim Hye-jin's short stories also represent mobility that cannot move and hesitates. These stories are important in that they show the mobility as a dispositif that constitutes the subject. When referring to the achievements of Mobility and Foucault, we read this narrative again by paying attention to the dynamics of mobility and immobility in the text. The significance of this paper is that it expands mobility-based textual research anew. While text analysis applying mobility study was usually focused on clearly mobile narratives such as travel statements and diaspora narratives, Mobility and Foucault drives new textual research by paying attention to the relationship between power and mobility, mobility and immobility dynamics. Therefore, this paper is significant in confirming the new meaning of the text revealed when paying attention to the representation of mobility in the narrative that no one seems to be mobile, and seeking to expand the mobility-based textual research method.