• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.36-41
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• 2016

LDPC code has beend applied in recent communication standards, such as Wi-Fi, WiGig, 10GBased-T Ethernet as a forward error correction code. However, LDPC code is required a large amount of computational complexity due to large iterations and block lengths for high performances. To solve this problem, various research has been continously performed for reducing computational complexity. In this paper, we propose AFC algorithm to deactive the variable and check node for reduce the computational complexity.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.9
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• pp.595-602
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• 2013

WiFi fingerprinting is well known as an effective localization technique used for indoor environments. However, this technique requires a large amount of pre-built fingerprint maps over the entire space. Moreover, due to environmental changes, these maps have to be newly built or updated periodically by experts. As a way to avoid this problem, crowd-sourced fingerprint mapping attracts many interests from researchers. This approach supports many volunteer users to share their WiFi fingerprints collected at a specific environment. Therefore, crowd-sourced fingerprinting can automatically update fingerprint maps up-to-date. In most previous systems, however, individual users were asked to enter their positions manually to build their local fingerprint maps. Moreover, the systems do not have any principled mechanism to keep fingerprint maps clean by detecting and filtering out erroneous fingerprints collected from multiple users. In this paper, we present the design of a crowd-sourced fingerprint mapping and localization(CMAL) system. The proposed system can not only automatically build and/or update WiFi fingerprint maps from fingerprint collections provided by multiple smartphone users, but also simultaneously track their positions using the up-to-date maps. The CMAL system consists of multiple clients to work on individual smartphones to collect fingerprints and a central server to maintain a database of fingerprint maps. Each client contains a particle filter-based WiFi SLAM engine, tracking the smartphone user's position and building each local fingerprint map. The server of our system adopts a Gaussian interpolation-based error filtering algorithm to maintain the integrity of fingerprint maps. Through various experiments, we show the high performance of our system.

• TTA Journal
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• s.153
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• pp.86-90
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• 2014

• TTA Journal
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• s.154
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• pp.72-77
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• 2014

• TTA Journal
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• s.139
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• pp.104-110
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• 2012

• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.158-162
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• 2012

In this paper, we propose a wireless modem, which used OFDM/64QAM method and the ISM band with 2.4GHz radio frequency. In this paper proposed the case of a modem, the main program to process the baseband processor, processing speed, operating voltage, and reliability should be ensured. So we have designed with Ralink's RT2870, witch was used for Wi-Fi solution. The RT2870 provides full support for wireless LAN standard, and supports various modulation formats, 2.4GHz and 5GHz bands, both of which support chip. In this paper, we also output the modulated signal transmitted wirelessly to the 2.4GHz band RF RT2850 chip processing was applied and using 40MHz band 2.422 ~ 2.462GHz wireless bands were designed to occupy. By applying bi-directional transmission between wireless transmitter and receiver, it can be effectively connected with any kinds of wireless LAN with 2.4GHz ISM band. Therefore it could economically be used as peripheral equipments for POS system or personal wireless device based on Android platform.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.55-61
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• 2016

As the price-performance ratio of embedded PCs improves, the benefits of the PC-Fi can be maximized by designing an embedded PC-Fi system. In this paper presents the design of an embedded PC-Fi that can be manipulated by a remote controller based on mobile devices such as smart phones or tablets. Additionally, an interactive control system and its GUI, through which the user can select and play music as they like at ease, are presented. The case that a large amount of music is stored in the PC-Fi system requires a function allowing the user to easily select the music they want to listen to. In order to implement this function, a DB containing detailed information of each track can be used to find the location of the desired music with keywords provided by the user. In this proposed system, the embedded PC-Fi system and remote controller are mutually connected via a WiFi network, and more than one user can remotely control the embedded system with their own mobile device.

• Journal of IKEEE
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• v.24 no.1
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• pp.90-96
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• 2020

As various communication services have emerged due to the development of mobile communication technology, there is a need for a wideband antenna supporting multiple communication services with one antenna. In this paper, we propose a planar slot wideband antenna that can support all the communication services of 3.1~4.99GHz, the low frequency band of 5G, in addition to the existing communication services such as WiFi, LTE 2300/2500, and WiMAX. Through the simulation, the optimized antenna design parameters were obtained, and the antenna was fabricated to implement an antenna with a frequency bandwidth of 1.96~6.01GHz (S11 <-10dB) and presented the radiation pattern and gain of the antenna. The proposed antenna is a multi-band antenna that can provide all the services of LTE, Wifi, WiMAX, and 5G low frequency bands. It can be used as a repeater antenna in radio shadow area such as buildings, dense areas, and ships.

• Journal of Korea Multimedia Society
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• v.19 no.2
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• pp.451-459
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• 2016

The damages on the crops by the wild animals such as wild boars and water deer are serious in rural areas these days. In this paper, a low-cost and adaptive system based on open source for sensing and repelling farm pest animals is proposed. The system contains the server which is Arduino Due connected with the wireless communication modules such as RF, Zigbee, and WiFi module, speaker, and so on. It also has the sensing modules and LED blinkers which communicates with the server by wireless modules. Once a detecting signal is transmitted to the server. The server is waked up from sleep mode and the repelling subsystems such as loud speaker and LED blinker(s) are activated to scare the unwanted animal away. The total system is managed by Android smartphone easily.

• Information and Communications Magazine
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• v.30 no.9
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• pp.3-12
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• 2013

N Screen 서비스는 하나의 콘텐츠를 스마트폰, PC, 태블릿, 자동차 등 다양한 디지털 정보기기에서 공유할 수 있는 차세대 컴퓨팅, 네트워크 서비스를 말한다. 이는 시간, 장소, 디지털 기기에 구애 없이 언제 어디에서나, 어떠한 기기에서나 하나의 콘텐츠를 이어서 볼 수 있고, 사용자는 가장 편리한, 가장 좋은 환경의 기기에서 원하는 콘텐츠를 즐길 수 있다. 본고에서는 N Screen 서비스를 위한, 기기 간의 연동 기술을 홈 네트워크의 대표적인 UPnP, DLNA 표준과 특정 업체를 중심으로한 DIAL, AllJoyn 기술 및 스마트 TV 플랫폼에서 출발한 STA (Smart TV Alliance)의 N Screen 서비스 적용 그리고, Wi-Fi 통신망을 이용한 Wi-Fi Display 표준기술을 소개하고 서로 비교 함으로써, 기기간의 N Screen 서비스 기술 및 표준화 발전 방향을 살펴보고자 한다.