• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.110-132
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• 2019

To ensure reliable and secure communication in heterogeneous cellular network (HCN) with imperfect channel state information (CSI), we proposed a coordinated multipoint (CoMP) transmission scheme based on dual-threshold optimization, in which only base stations (BSs) with good channel conditions are selected for transmission. First, we present a candidate BSs formation policy to increase access efficiency, which provides a candidate region of serving BSs. Then, we design a CoMP networking strategy to select serving BSs from the set of candidate BSs, which degrades the influence of channel estimation errors and guarantees qualities of communication links. Finally, we analyze the performance of the proposed scheme, and present a dual-threshold optimization model to further support the performance. Numerical results are presented to verify our theoretical analysis, which draw a conclusion that the CoMP transmission scheme can ensure reliable and secure communication in dense HCNs with imperfect CSI.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.1
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• pp.9-16
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• 2019

Smartphones are becoming a portable computer. As a result, even the most sensitive financial application services are now available anywhere on the smartphone. Compared to general PCs, smartphones communicate with external devices through various channels such as wireless internet, mobile communication network, Bluetooth, and NFC, and a wide variety of applications are provided. Therefore, if vulnerabilities exist, the possibility of attack damage increases. In this paper, we analyze the vulnerabilities of dynamic virtual keyboards used in login of banking apps of smartphones with various physical constraints and propose countermeasures.

• ETRI Journal
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• v.40 no.6
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• pp.745-758
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• 2018

A wide range of studies in various disciplines has focused on the Internet of Things (IoT) and cyber-physical systems (CPS). However, it is necessary to summarize the current status and to establish future directions because each study has its own individual goals independent of the completion of all IoT applications. The absence of a comprehensive understanding of IoT and CPS has disrupted an efficient resource allocation. To assess changes in the knowledge structure and emerging technologies, this study explores the dynamic research trends in IoT by analyzing bibliographic data. We retrieved 54,237 keywords in 12,600 IoT studies from the Scopus database, and conducted keyword frequency, co-occurrence, and growth-rate analyses. The analysis results reveal how IoT technologies have been developed and how they are connected to each other. We also show that such technologies have diverged and converged simultaneously, and that the emerging keywords of trust, smart home, cloud, authentication, context-aware, and big data have been extracted. We also unveil that the CPS is directly involved in network, security, management, cloud, big data, system, industry, architecture, and the Internet.

• Agribusiness and Information Management
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• v.10 no.2
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• pp.18-27
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• 2018

This study aims to confirm the appropriateness of fruit and vegetable sales at military commissaries, with the purpose of enhancing the physical health and morale of military personnel. In order to achieve this objective, we examined the actual conditions of fruit and vegetable sales at military commissaries and analyzed the soldiers' awareness of fruit and vegetable sales through questionnaire surveys. The conclusions of this study are as follows: Firstly, fresh fruits and vegetables were not sold at military commissaries. Secondly, soldiers acknowledged the need for the consumption of fruits and vegetables and strongly expressed the desire for these fresh food products to be sold at military commissaries. Although the ROK Navy privatized military commissaries for the purposes of increasing management efficiency of national defense and strengthening combat power by transferring PX salesclerk soldiers to join combat personnel, this effort produced a negative effect of price increase. The following are proposals for improving this condition: fruit and vegetable products should be introduced to military commissaries through military welfare funds; fresh food markets should be established by closely cooperating with the local community's agricultural producers; processed fruit and vegetable product (dry, frozen, airtight packaged, etc.) sales should be increased; and the privatization of the navy commissaries should be abolished.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5234-5251
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• 2018

It is well-known that virtualization technology can bring many benefits not only to users but also to service providers. From the view of system security and resource utility, higher resource sharing degree and higher system reliability can be obtained by the introduction of virtualization technology in distributed cloud. The small size time-sharing multiplexing technology which is based on virtual machine in distributed cloud platform can enhance the resource utilization effectively by server consolidation. In this paper, the concept of memory block and user satisfaction is redefined combined with user requirements. According to the unbalanced memory resource states and user preference requirements in multi-virtual machine environments, a model of proper memory resource allocation is proposed combined with memory block and user satisfaction, and at the same time a memory optimization allocation algorithm is proposed which is based on virtual memory block, makespan and user satisfaction under the premise of an orderly physical nodes states also. In the algorithm, a memory optimal problem can be transformed into a resource workload balance problem. All the virtual machine tasks are simulated in Cloudsim platform. And the experimental results show that the problem of virtual machine memory resource allocation can be solved flexibly and efficiently.

• ETRI Journal
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• v.43 no.5
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• pp.941-949
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• 2021

In this study, a spatial spectrum method is proposed to cope with the pilot spoofing attack (PSA) problem by exploiting the of uplink-downlink channel reciprocity in time-division-duplex multiple-input multiple-output systems. First, the spoofing attack in the uplink stage is detected by a threshold derived from the predefined false alarm based on the estimated spatial spectrum. When the PSA occurs, the transmitter (That is Alice) can detect either one or two spatial spectrum peaks. Then, the legitimate user (That is Bob) and Eve are recognized in the downlink stage via the channel reciprocity property based on the difference between the spatial spectra if PSA occurs. This way, the presence of Eve and the direction of arrival of Eve and Bob can be identified at the transmitter end. Because noise is suppressed by a spatial spectrum, the detection performance is reliable even for low signal-noise ratios and a short training length. Consequently, Bob can use beamforming to transmit secure information during the data transmission stage. Theoretical analysis and numerical simulations are performed to evaluate the performance of the proposed scheme compared with conventional methods.

• Safety and Health at Work
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• v.12 no.2
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• pp.154-166
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• 2021

Background: Occupational health and safety (OHS) is a significant interest of all governments to prevent workplace hazards. Although appropriate legislation and regulations are essentials for the protection of workers, they are solely not enough. Application of them in practice should be secured by an efficient inspection system. Fundamental components of an inspection system are inspectors and their audit tasks. Maintaining the fair balanced task assignment among inspectors strictly enhances the efficiency of the overall system. Methods: This study proposes a two-phased goal programming approach for OHS inspectors' task assignments and presents a case study. Results: The solution approach gives the balanced assignment of inspectors to the workplaces in different cities of the country in the planning period. The obtained schedule takes into account the distances covered by the work places and the number of the workplaces' employees to be audited and pays attention to the human factors by considering the preferences of the inspectors. The comparisons between the obtained optimal schedule and the implemented one that is produced manually show that the approach not only maintains the technical requirements of the problem, but also provides social and physical balance to the task assignment. Conclusion: Both the approach and the application study are expected to offer fruitful inspirations in the area of safety management and policy and they provide a good guide for social policy and organizational aspects in the field of OHS inspectors' task assignment.

• Health Policy and Management
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• v.30 no.4
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• pp.431-432
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• 2020

Coronavirus disease 2019 (COVID-19) has been going on for nearly a year. As of December 1, 2020, more than 60 million confirmed cases and 1.4 million deaths have occurred in 220 countries and territories. There is no effective treatment for COVID-19 so far, and vaccines are being developed. However, the vaccine of COVID-19 can be freed from COVID-19 only if there are positive answers to some questions: "Aren't there any major side effects from the vaccine?"; "Is the vaccine effective for enough time?"; "Does the vaccine sufficiently reduce the mortality rate?"; and "Does the vaccine sufficiently reduce the reproduction number?" The fight against COVID-19 will continue for a long time. Therefore, we need to respond by developing the evidence for control of COVID-19, the emerging infectious disease. Extensive quarantine measures in the early stages of COVID-19 need to be elaborated through developing the evidence. Korea Disease Control and Prevention Agency should establish a database for evidence developing COVID-19 control. In this database, based on more than 3 million tested individuals, epidemiological investigation results, health insurance claims data, and government data such as the Ministry of Public Administration and Security, etc. should be linked. It is necessary to disclose this database to academia, etc. to create the evidences of COVID-19 and manage COVID-19 through these. And through the developed evidences, guidelines for physical health and mental health in the era of Corona 19 should be developed.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.4
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• pp.119-126
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• 2022

In this paper, we present important factors and methodologies that we have to follow for secure and efficient package management systems in a closed network. By analyzing previous works, we present several security considerations for the existing package management systems. Based on the consideration, we propose guidelines regarding the use of package management systems in the closed network. More specifically, we propose the development of new package management tools, utilization of physical storage media, utilization of local backup repositories, package updates, and downgrade batches for secure and efficient package management.

• Journal of Multimedia Information System
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• v.9 no.1
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• pp.51-60
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• 2022

This paper raised the need to examine how the online education environment triggered by COVID-19 and the smart learning environment can be established in consideration of the improvement of education and learning through learning analysis. Many studies are being conducted in Korea, and the Ministry of Education is continuously striving to build a smart school by promoting strategies for promoting smart education on the way to a talent powerhouse. Nevertheless, there is no unified definition of smart learning, and it can be seen as customized (individualized) learning using smart devices. However, most of the discussions on the construction of smart schools so far have limitations in that they are limited to physical spaces. Accordingly, the opinions of teachers and learners were not sufficiently reflected in the establishment of the facility. This study intends to study smart learning in various departments. In addition, the subjects students in charge of the co-researcher of this study were analyzed. The total number of subjects was 951, and 434 responded to this study survey. In addition, students were well accepting the online environment, and in the future, regardless of COVID-19, research will be presented to improve mutual communication between professors and students in smart learning.