• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.1941-1960
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• 2019

Unmanned aerial vehicles (UAVs), acting as mobile base stations (BSs), can be deployed in the typical fifth-generation mobile communications (5G) scenarios for the purpose of substantially enhancing the radio coverage. Meanwhile, UAV aided underlay device-to-device (D2D) communication mode can be activated for further improving the capacity of the 5G networks. However, this UAV aided D2D communication system is more vulnerable to eavesdropping attacks, resulting in security risks. In this paper, the D2D receivers work in full-duplex (FD) mode, which improves the security of the network by enabling these legitimate users to receive their useful information and transmit jamming signal to the eavesdropper simultaneously (with the same frequency band). The security communication under the UAV coverage is evaluated, showing that the system's (security) capacity can be substantially improved by taking advantage of the flexible radio coverage of UAVs. Furthermore, the closed-form expressions for the coverage probabilities are derived, showing that the cellular users (CUs)' secure coverage probability in downlink transmission is mainly impacted by the following three factors: its communication area, the relative position with UAV, and its eavesdroppers. In addition, it is observed that the D2D users or DUs' secure coverage probability is relevant to state of the UAV. The system's secure capacity can be substantially improved by adaptively changing the UAV's position as well as coverage.

• 한국전자통신학회논문지
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• 제8권10호
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• pp.1589-1594
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• 2013

차량통신은 IT기술과 차량산업을 결합한 대표적인 융합기술이다. WAVE 기술은 전 세계적으로 널리 채택되어 사용되어지고 있는 차량통신 표준이다. 본 논문에서는 WAVE 시스템 이용하여 실제 테스트베드상에서 구현한 서비스에 대해 소개한다. 먼저 전체적인 WAVE 시스템에 대해 간략히 살펴본 후 서비스를 구현하기 위한 테트스베드에 대해 소개하고, 테스트베드상에서 구현된 차량간통신 및 차량 기지국간통신을 이용한 다양한 응용 서비스에 대해 알아본다. 실제 응용 서비스의 구현을 바탕으로 하여 실제 시스템 구현에 필요한 사항 및 다른 분야와의 융합분야에 대해서도 논의한다.

• 한국정보전자통신기술학회논문지
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• 제4권4호
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• pp.295-299
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• 2011

Blind equalization techniques have been widely used in wireless communication systems. In this paper, we propose to apply the balanced information potentials to the criterion of minimum Euclidian distance between two PDFs with constant modulus errors for adaptive blind equalizers. One of the two PDFs is constructed with constant modulus error samples and another does with Dirac delta functions. Two information potentials derived from the criterion are balanced in order to have better performance by putting a weighting factor to each information potentials. The proposed blind algorithm has shown in the MSE convergence performance that it can produce enhanced performance by over 3 dB of steady state MSE.

• International Journal of Internet, Broadcasting and Communication
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• 제13권4호
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• pp.66-71
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• 2021

The purpose of this paper is to identify keywords related to museums, gamification, and visitors, and provide basic data that the museum market can be expanded by using gamification. That used to collect data for blogs, news, cafes, intellectuals, academic information by Naver and Daum which is Web documents in Korea, and Google Web, news, Facebook, Baidu, YouTube, and Twitter for analysis. For the data analysis period, a total of one year of data was selected from April 16, 2020 to April 16, 2021, after Corona. For data collection and analysis, the frequency and matrix of keywords were extracted through Textom, a social matrix site, and the relationship and connection centrality between keywords were analysed and visualized using the Netdraw function in the UCINET6 program. In addition, We performed CONCOR analysis to derive clusters for similar keywords. As a result, a total of 25,761 cases that analysing the keywords of museum, gamification and visitors were derived. This shows that the museum, gamification, and spectators are related to each other. Furthermore, if a system using gamification is developed for museums, the museum market can be developed.

• ETRI Journal
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• 제37권2호
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• pp.262-272
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• 2015

In particular, for a practical mobile robot team to perform such a task as that of carrying out a search and rescue mission in a disaster area, the network connectivity and localization have to be guaranteed even in an environment where the network infrastructure is destroyed or a Global Positioning System is unavailable. This paper proposes the new collective intelligence network management architecture of multiple mobile robots supporting seamless network connectivity and cooperative localization. The proposed architecture includes a resource manager that makes the robots move around and not disconnect from the network link by considering the strength of the network signal and link quality. The location manager in the architecture supports localizing robots seamlessly by finding the relative locations of the robots as they move from a global outdoor environment to a local indoor position. The proposed schemes assuring network connectivity and localization were validated through numerical simulations and applied to a search and rescue robot team.

• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.629-632
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• 2011

RFID technology is one of the verification technology that use radio frequency. Use and study of RFID are on the increase because RFID is a one of main technologies in ubiquitous. In this paper, we address to develop a Record Processing System using RFID. The purpose of this paper is improvement of accuracy and efficiency on Record Processing System by applying RFID. Later, this paper will be able to help to establish of u-Campus.

• International journal of advanced smart convergence
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• 제4권2호
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• pp.84-93
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• 2015

This study is for the development of Cover Glass Grinding Processing System. This system is developed for manufacturing a mass product system grinding cover glasses with highly precise mechanism, and we improved resulted quality. In the development process, we developed a complete process technology through mechanical design, image processing technology, spindle control, mark identification algorithm etc. With this cover glass grinding development, we could developed process technology, image processing technology, organization mechanisms and control algorithms.

• Journal of information and communication convergence engineering
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• 제8권4호
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• pp.393-398
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• 2010

For multi-cell environments, coordinated random beamforming technique in multiuser MIMO(multiple-input multiple-output) broadcast channel is considered. In order to mitigate severe interference at receivers, the multi-cell environments might require complex transmitter and receiver design because the scheduler decision based on full channel state information (CSI) in one cell must be intertwined with decision made by other cells' CSI. With limited CSI, however, this paper considers a scheme of randomizing transmitters' beamforming but being coordinated with other cell transmitters. The transmitters in each cell share random beamforming patterns and schedule data transmission within coherent scheduling period. The corandomized beams allow the users to be selected with the highest SINRs even in multi-cell environments. We analyze the performance of the proposed scheme. And numerical results show that the scheme achieves better performance than the conventional random beamforming when applying to multi-cell environments.

• Journal of electromagnetic engineering and science
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• 제17권4호
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• pp.233-237
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• 2017

In this paper, a dual-band high frequency (HF) and ultra-high frequency (UHF) radio-frequency identification (RFID) tag antenna is presented that operates in the 13.56 MHz band as well as in the 920 MHz band. A spiral coil along the edges of the antenna substrate is designed to handle the HF band, and a novel meander open complementary split ring resonator (MOCSRR) dipole antenna is utilized to generate the UHF band. The dual-band antenna is supported by a single-feeding port for mono-chip RFID applications. The antenna is fabricated using an FR4 substrate to verify theoretical and simulation designs, and it has compact dimensions of $80mm{\times}40mm{\times}0.8mm$. The proposed antenna also has an omnidirectional characteristic with a gain of approximately 1 dBi.

• 한국IT서비스학회지
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• 제10권4호
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• pp.33-46
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• 2011

This research focus on the economic activity as consumer and producer traits of future customers in the convergence age. We assess level of convergence for digital devices and services respectively by questionnaire survey and interview for 14 professions. And then, for evaluating convergence level and usage of digital services of each respondents, we conducted the questionnaire survey for 343 samples. Findings of our research hold that the group who showed higher level of convergence tends to use the socialized digital services more. Convergence generation were heavy users in appstore on smart-phone and wireless game and more participating. In digital service area, facebook/cyworld, twitter, UCC, portal, internet community in digital service. Convergence generation are global network communication, buying decision making activity, actively opinion expression, prosumer attitude, dependency on digital device, experience based purchase behavior, enthusiastic information sharing.