• Asian Journal for Public Opinion Research
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• v.5 no.1
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• pp.1-14
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• 2017

The Fukushima nuclear accident caused by an earthquake and a subsequent tsunami on March 11, 2011 has seriously impacted the environment surrounding the Fukushima Daiichi nuclear power plant. While all the residents near the plant were evacuated from the area deemed uninhabitable after the accident, residents of the neighboring area outside of the evacuation zone still seem to live in fear of invisible radiation. To understand Fukushima residents' thinking about the environmental risks that accompany a nuclear disaster, we utilize a poll of the residents of Fukushima conducted in 2013. Based on the survey data, we reveal factors that seem to strongly affect their knowledge and concerns about nuclear power plants. The results of the multivariate analysis show the importance of the following two factors: (1) confidence in mass media, and (2) trust in institutions in charge of administering the accident, especially the central government, the Nuclear and Industrial Safety Agency, and Tokyo Electric Power Company. We conclude that the more people trust mass media and particular institutions, the more likely it is that they are have an elevated sense of anxiety and fear of the presence of nuclear plants.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2037-2051
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• 2012

Cognitive radio (CR) is envisioned as a promising paradigm of exploiting intelligence for enhancing efficiency of underutilized spectrum bands. In CR, the main concern is to reliably sense the presence of primary users (PUs) to attain protection against harmful interference caused by potential spectrum access of secondary users (SUs). In this paper, evolutionary algorithms, namely, particle swarm optimization (PSO) and genetic algorithm (GA) are proposed to minimize the total sensing decision error at the common soft data fusion (SDF) centre of a structurally-centralized cognitive radio network (CRN). Using these techniques, evolutionary operations are invoked to optimize the weighting coefficients applied on the sensing measurement components received from multiple cooperative SUs. The proposed methods are compared with each other as well as with other conventional deterministic algorithms such as maximal ratio combining (MRC) and equal gain combining (EGC). Computer simulations confirm the superiority of the PSO-based scheme over the GA-based and other conventional MRC and EGC schemes in terms of detection performance. In addition, the PSO-based scheme also shows promising convergence performance as compared to the GA-based scheme. This makes PSO an adequate solution to meet real-time requirements.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.201-209
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• 2016

In wireless sensor networks (WSNs) duty cycling has been an imperative choice to reduce idle listening but it introduces sleep delay. Thus, the conventional WSN medium access control protocols are bound by the energy-latency tradeoff. To break through the tradeoff, we propose a radio wave sensor called radio frequency (RF) wakeup sensor that is dedicated to sense the presence of a RF signal. The distinctive feature of our design is that the RF wakeup sensor can provide the same sensitivity but with two orders of magnitude less energy than the underlying RF module. With RF wakeup sensor a sensor node no longer requires duty cycling. Instead, it can maintain a sleep state until its RF wakeup sensor detects a communication signal. According to our analysis, the response time of the RF wakeup sensor is much shorter than the minimum transmission time of a typical communication module. Therefore, we apply duty cycling to the RF wakeup sensor to further reduce the energy consumption without performance degradation. We evaluate the circuital characteristics of our RF wakeup sensor design by using Advanced Design System 2009 simulator. The results show that RF wakeup sensor allows a sensor node to completely turn off their communication module by performing the around-the-clock carrier sensing while it consumes only 0.07% energy of an idle communication module.

• Journal of Korea Multimedia Society
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• v.24 no.8
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• pp.1101-1113
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• 2021

The rapid growth of sense-and-respond applications and the emerging cloud computing model present a new challenge: providing publish/subscribe middleware as a scalable and elastic cloud service. The publish/subscribe interaction model is a promising solution for scalable data dissemination over wide-area networks. In addition, there have been some work on the publish/subscribe messaging paradigm that guarantees reliability and availability in the face of node and link failures. These publish/subscribe systems are commonly used in information-centric networks and edge-fog-cloud infrastructures for IoT. The IoT has an edge-fog cloud infrastructure to efficiently process massive amounts of sensing data collected from the surrounding environment. In this paper. we propose a quorum-based hierarchical fault-tolerant publish/subscribe systems (QHFPS) to enable reliable delivery of messages in the presence of link and node failures. The QHFPS efficiently distributes IoT messages to the publish/subscribe brokers in fog overlay layers on the basis of proposing extended stepped grid (xS-grid) quorum for providing tolerance when faced with node failures and network partitions. We evaluate the performance of QHFPS in three aspects: number of transmitted Pub/Sub messages, average subscription delay, and subscritpion delivery rate with an analytical model.

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.4
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• pp.357-367
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• 2000

A new robust load-frequency control methodology is proposed for nonlinear power systems with valve position limits of the governor in the presence of parametric uncertaines. The TSK fuzzy model is adopted and formulated for fuzzy modeling of the nonlinear power system. A sufficient condition of the robust stabilitry is presented in the sense of lyapunov for the TSK model with parametric uncertainties. The intekkigent digital redesign technique for the uncertain power systems is also studied. The effectiveness of the robust digital fuzzy controller disign mothod is demonstrated through a numerical simulation.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.73-82
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• 2004

This paper presents the study on damage diagnosis of an intelligent cantilevered beams using PZT actuator and PVDF sensor This study provides the theoretical and experimental verification to examine structural damage. Time domain analysis for the non-destructive detection of damage is presented by parameterized partial differential equations and Galerkin approximation techniques. The time histories of the vibration response of structure were used to identify the presence of damage. Furthermore, this systematic approach permits one to use the piezomaterials to both excite and sense the vibration of structures. We also carried out the experimental verification about reliability of theoretical methods fur detecting the damage of a composite beam with PZT actuator and PVDF sensor. Experimental results are presented from tests on cantilevered composite beams which is damaged at different location and different dimensions. The results were compared with the simulation results. Good agreement between the results was found for the time shifts and amplitude difference in transients response of the cantilevered beam.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1801-1806
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• 2004

Stochastic nature of subgrid-scale stress causes the predictability problem in large eddy simulation (LES) by which the LES solution field decorrelates with field from filtered directnumerical simulation (DNS). In order to evaluate the predictability limit in a priori sense, the information on the interplay between resolved scale and subgrid-scale (SGS) is required. In this study, the analysis on the inter-scale interaction is performed by applying tophat and cutoff filters to DNS database of flow over a circular cylinder at Reynolds number of 3900. The effect of filter shape is investigated on the interpretation of correlation between scales. A critique is given on the use of tophat filter for SGS analysis using DNS database. It is shown that correlations between Karman vortex and SGS kinetic energy drastically decrease when the cutoff filter is used, which implies that the small scale universality holds even in the presence of the large scale coherent structure.

• Journal of Korea Multimedia Society
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• v.25 no.3
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• pp.502-509
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• 2022

With the development of media technology, virtual reality (VR) technology is widely used in education, medical care, aerospace, entertainment and other fields. Among them, application in teaching courseware is a relatively new topic. Compared with traditional coursewares, virtual games visualized and extruded abstract teaching contents. Thus it strengthened teaching effects and expanded dimensions of learning. We hypothesized that virtual coursewares could increase users'sense of presence and enhance their focus. In this study, virtual courseswares were compared with traditional coursewares. At the same time, its feasibility and advantages of application were analyzed through literature researching, practical researching and statistical analysis from questionnaires. Furthermore, we designed a teaching system for VR coursewares and explored its performance in multidimensional and contextual teaching situations. It was found that Virtual coursewares have changed the boring traditional teaching methods. The teaching content was displayed in the form of three-dimensional images, videos and sounds through VR equipment, which effectively improved teaching efficiency. In addition, the feasibility of virtual courseware was demonstrated through factor analysis in questionnaires. Compared with traditional teaching courseware, VR coursewares can attract students' attention and improve learning efficiency. It provides a good example and is valuable for the research of virtual realities in education.

• Journal of Information Science Theory and Practice
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• v.11 no.4
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• pp.90-108
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• 2023

The purpose of this study is to investigate how uses and gratifications motivations increase social media stickiness, with a special focus on media engagement as a key mediator. Data were gathered via a survey questionnaire from Bangladeshi Z Generation social media users, which was quantitative in nature. For the analysis of 258 survey samples, structural equation modeling methodology was used. The results show that social media engagement and social media stickiness are positively impacted by uses and gratifications motivations such as social interaction, information, convenience, and entertainment. The study also found evidence of a relationship between uses and gratification motivations and social media stickiness, which is also mediated by emotional attachment. Understanding the motivations and gratifications sought by Z Generation users on social media platforms can help design strategies to enhance engagement and loyalty, ultimately leading to improved user retention and platform success. By identifying and addressing the specific needs and desires of the Z Generation, social media platforms can tailor their features, content, and user experiences to foster a stronger sense of connection and satisfaction, resulting in increased user engagement and prolonged usage.

• Journal of Multimedia Information System
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• v.4 no.3
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• pp.151-156
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• 2017

As Internet services have spread centering on mobiles, diverse services used in everyday life have become mobile services. For humans, residential spaces have significant implications as physical and psychological environments. Therefore, being provided with accurate information on the room that must be sought to find out the residential space wanted by the user can be said to be an important element of real estate apps. However, when buying real estate, people prefer searching for information using mobiles and verifying the information by visiting the real estate firsthand due to increases in damage due to false offerings. This way approaches as inconvenience in cases where the buyer lives far away or if the conditions are not suitable. Therefore, in the present study, a 'room finding application using VR' was designed and implemented using virtual reality (VR) used for diverse purposes. VR is a technology that provides the user with the sense of presence as if the user is actually present in the space. It was used in the present study as a means to provide more accurate information. The use of the application designed and implemented in the present study is expected to reduce false offerings information at least slightly so that users can be provided with more accurate information on the real estate of interest.