• Journal of Platform Technology
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• v.8 no.2
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• pp.10-21
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• 2020

The use of WiFi is gradually increasing through the spread of mobile terminals and the development of data communication. Mobile Internet usage has been steadily increasing from the 2000s to the present. Almost all households in Korea have smart devices, and 90% of the population uses mobile Internet. Due to this trend, the government is currently constructing public WiFi zones in dense urban areas as a way to reduce communication costs. The WiFi usage in the public WiFi zone is increasing every year. Therefore, in this paper, we propose a method for using such public WiFi efficiently. A mobile terminal collects WiFi information and constructs a WiFi zone in a map using a concave hull algorithm. In the map, the mobile terminal provides a route through many public WiFi areas. As a result, the WiFi usage of the mobile terminal is increased through more WiFi regions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5479-5486
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• 2012

In this paper, we have measured PRR, RSSI and LQI of ZigBee channels under Wi-Fi environment and have assessed channel characteristic and link quality. To confirm any relationship among RSSI, LQI values and PRR under Wi-Fi interference in overlapping and non-overlapping channels of Wi-Fi and ZigBee, the experiments were performed without Wi-Fi, with Wi-Fi and file download through Wi-Fi. Under Wi-Fi interference, We perfomed experiments to ensure channel characteristics and link quality by fixing Wi-Fi and ZigBee receiver and varying the distance between ZigBee receiver and transmitter. ZigBee transmitter sends packet of 256 bits every second to ZigBee receiver. PRR was measured from ZigBee with variance of distance between fixed Wi-Fi and ZigBee. RSSI, LQI, PRR were measured from ZigBee with fixed Wi-Fi, fixed ZigBee receiver and variance of distance of ZigBee transmitter. As a result, we confirmed decrease of PRR under Wi-Fi interference but RSSI, LQI values similar regardless of overlapped or non-overlapped channel and Wi-Fi interference. Therefore, PRR should be used for interference detection in ZigBee communication under Wi-Fi environment but RSSI and LQI are not appreciate.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.476-483
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• 2016

Super Wi-Fi is a Wi-Fi-like service exploiting TV white space (WS) which is expected to achieve larger coverage than today's Wi-Fi thanks to its superior propagation characteristics. Super Wi-Fi has been materialized as an international standard, IEEE 802.11af, targeting indoor and outdoor applications, and is undergoing worldwide field tests. This paper demonstrates the true potential of indoor Super Wi-Fi, by experimentally comparing the signal propagation characteristics of Super Wi-Fi and Wi-Fi in the same indoor environment. Specifically, we measured the wall and floor attenuation factors and the path-loss distribution at 770MHz, 2.401 GHz, and 5.540 GHz, and predicted the downlink capacity of Wi-Fi and Super Wi-Fi. The experimental results have revealed that TVWS signals can penetrate up to two floors above and below, whereas Wi-Fi signals experience significant path loss even through a single floor. It has been also shown that Super Wi-Fi mitigates shaded regions of Wi-Fi by providing almost-homogeneous data rates within its coverage, performs comparable to Wi-Fi utilizing less bandwidth, and always achieves better spectral efficiency than Wi-Fi. The observed phenomena imply that Super Wi-Fi is suitable for indoor applications and has the potential of extending horizontal and vertical coverage of today's Wi-Fi.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.11
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• pp.1050-1057
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• 2012

Super Wi-Fi is a newly emerging wireless Internet technology, which constitutes Wi-Fi networks using TV white space. A key technical challenge in the Super Wi-Fi applications is how to provide a seamless Internet service even when a Super WiFi user should give up the channel in use to the active incumbent user which is activated in the same service area, preventing from the service continuity in Super Wi-Fi. In this paper, we propose a channel handover method to support service continuity of Super Wi-Fi, in which an AP selects a new operational channel and provides the channel information for MSs. Therefore, the AP and the MSs can carry out seamless handover for Super Wi-Fi service. A performance evaluation shows that the proposed scheme is superior to the conventional Wi-Fi in channel mobility delay.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.53-63
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• 2009

This paper is to develop WiMAX CPE(wireless AP) that can provides Wi-Fi terminal with wireless Internet service by connecting to Wibro wireless network. This AP aims to support WiBro in upstream interface basically, and Wi-Fi and 100M Ethernet interface in downstream. So, we has developed the equipment for business that wireless ISP can provide many Internet customers with wireless Internet service by using Wi-Fi terminal in subway, car, ship, and so on, and the equipment for users that a user can purchase and then install in person. For the latter, multiple Wi-Fi terminals that be registered in WiBro service can be connected to Internet simultaneously.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.167-172
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• 2010

This paper is to implement HSDPA-CPE that can provides WiFi terminal with wireless Internet service through the connection to HSDPA wireless network. This system aims to support HSDPA interface in upstream, and WiFi and 100Mbps Ethernet interface in downstream. So, this system can provide multiple Internet customers with wireless Internet service by using WiFi terminal in subway, car, ship, and so on, and WiFi terminals that be registered in HSDPA service can be connected to Internet.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2143-2148
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• 2016

Recently due to development of IT technology, ideas and technology that blend with environment have evolved. This technology can help people's living environment and in the future it is an essential component of the connected society. In this paper, we propose WiT(WiFI Trashcan) which takes advantage of the IT technology fusion and environmental factors at the same time to create a more pleasant environment. WiT provides a free WiFi when trash is disposed in the trash can. WiT detects whether a user disposes trash, determines the volume of the trash and provides free WiFi. To detect trash we use ultrasonic sensor and trash weight is measured by using weight sensor. Also by using Phython programming the measured sensor value is transmitted to Raspberry Pie and WiFi delivery time is determined. We used Arduino and Raspberry Pi to design and implement WiT.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.270-273
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• 2016

Recently due to development of IT technology, ideas and technology that blends with environment has evolved. In this paper, we propose WiT(WiFI Trash-Can) which takes advantage of the IT technology fusion and environmental factors at the same time to create a more pleasant environment. WiT provides a free WiFi when disposing trash in the trash can. WiT which is synthetic name for WiFi and Trash-Can is a system that is provides free WiFi when people dispose litter to detect whether user had access and determined the volume of the trash disposed. WiT uses Arduino and Raspberry Pi to detect the amount of trash and provide WiFi output on the display to show the ability to design and implement the remaining amount of time available.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.34-41
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• 2011

At present wireless internet access service is available through the 3G network, mobile WiMAX and WiFi anytime and anywhere. In this environment where there are various networks, users should be able to select specific networks depending on different situations. And it is necessary to provide mobility support between homogeneous and between heterogenous networks. Given this situation, the many proposals have been presented to link 3G, which has the largest service area among various networks, with mobile WiMAX(IEEE 802.16e), or with WiFi(IEEE 802.11). But, recently, with the increasing volume of wireless internet use and wireless internet data, due to the advents of net-book, e-book and smart phone, the service area of WiFi and mobile WiMAX has rapidly expanded. Especially, the availability of real-time application such as internet phone has led to the relative shrinking of the proportion of 3G mobile communication network giving conventional voice service, and enlargement of those of wireless internet access networks like WiFi and mobile WiMAX. This paper suggests a handover scheme based on PMIPv6, whitch support mobility between WiFi and mobile WiMAX, and minimizes handover delay. In this scheme, the mobile node has a dual stack structure composed of two interfaces-WiFi and mobile WiMAX. Since WiFi dose not support mobility, it is suggested that the mobile node have the capacity to deal with handover signaling between gateway in case of handover between homogeneous networks. This handover scheme, suggested comparing with current handovers between homogeneous networks, has proved, in its analytic evaluation, to be able to reduce handover, transmission, and signaling overhead.

• Electronics and Telecommunications Trends
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• v.26 no.5
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• pp.74-82
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• 2011

최근 Wi-Fi Alliance는 Wi-Fi 기반의 Peer-to-Peer(P2P) 규격인 Wi-Fi Direct 기술의 발표와 함께 인증을 진행하고 있다. Wi-Fi Direct 기술은 TV, 노트북, 프린터, 카메라와 같은 휴대기기 및 모바일 단말 등에 탑재되어 Access Point(AP) 또는 라우터와 같은 별도의 장비 없이도 단말 간 직접 통신을 통하여 기기 간 콘텐츠 및 서비스를 사용할 수 있는 기반을 제공하는 기술이다. Wi-Fi Direct 기술은 빠른 전송속도와 전송거리를 제공함으로써 향후 일부 영역에서 블루투스 기술을 대체할 수 있을 것으로 기대된다. 또한 향후 Wi-Fi Direct 규격의 전체 기능을 구현한 스마트폰이 출시된다면 사용자 경험(UX)을 극대화 시킬 수 있는 혁신적인 모바일 서비스를 제공할 수 있을 것으로 기대된다. 본 고에서는 Wi-Fi Direct의 업계 동향과 Wi-Fi Direct의 동작 원리를 표준 기술 규격서를 통해 분석하여 요약 정리한다.