• Journal of Sensor Science and Technology
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• v.27 no.4
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• pp.254-258
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• 2018

A Wi-Fi signal network (WSN) system is introduced in this paper. This system consists of several data-transmitting sensor modules and a data-receiving server. Each sensor module and the server contain a unique intranet IP address. A piezoelectric accelerometer with a bandwidth of 12 kHz, a 24-bit analog-digital converter with a sampling rate of 15.625 kS/s, a 32-bit microprocessor unit, and a 1-Mbps Wi-Fi module are used in the data-transmitting sensor module. A 300-Mbps router and a PC are used in the server. The system is verified using an accelerometer calibrator. The voltage output from the sensor is converted into 24-bit digital data and transmitted via the Wi-Fi module. These data are received by a Wi-Fi router connected to a PC. The input frequencies of the accelerometer calibrator (320 Hz, 640 Hz, and 1280 Hz) are used in the data transfer verification. The received data are compared to the data retrieved directly from the analog-to-digital converter used in the sensor module. The comparison shows that the developed system represents the original data considerably well. Theoretically, the system can acquire vibration signals from 600 sensor modules at an accelerometer bandwidth of 15.625 kHz. However, delay exists owing to software processes, multiplexing between sensor modules, and the use of non-real time operating system. Hence, it is recommended that this system may be used to acquire vibration signals with up to 10 kHz, which is approximately 70% of the theoretical maximum speed of the system. The system can be upgraded using parts with higher performance

• Annual Conference of KIPS
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• 2009.04a
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• pp.163-164
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• 2009

최근 감시카메라의 사용률이 증가하고 있다. 개인 사업체, 전문 감시업체, 일반 기업 및 공공기관 등 감시카메라는 폭넓게 사용된다. 하지만 현재 설치된 감시카메라는 녹화된 감시영상이나 카메라 컨트롤을 관리자가 언제 어디서나 확인하고 조절할 수 없다는 단점이 있다. 이러한 단점을 해결하기 위해 TCP/IP기반의 네트워크에서 PDA로 Wi-Fi를 이용하여 접속한 후 감시카메라를 제어하거나 영상을 확인하는 방법을 제안하고 구현하였다. 제안하는 시스템은 서버 컴퓨터는 카메라의 영상을 받고 팬틸트 컨트롤을 하게한다. 클라이언트 컴퓨터는 PC와 PDA를 이용하여 서버에 접속한 뒤 실시간으로 영상을 받아오고 카메라 팬틸트를 컨트롤 한다. 본 논문에서 제안한 내용은 Wi-Fi가 사용가능한 곳에 있는 사용자가 언제 어디서나 감시카메라의 영상을 보고 컨트롤 하는데 유용할 것이다.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.233-237
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• 2008

This paper presents proposal for an application (only for Windows-based Mobile) that can synchronize the Third Generation Windows-based mobile with the prescribed server. This application can be used by mobile users to send information directly to the WAS server wirelessly. In this paper a comparison between Third Generation technology and WLAN ( both are parallel technologies first one embodied by IMT-2000 standards and the second one by ITU Standards) has been made and also a comparison between Wi-Fi and Bluetooth has been made.

• Journal of Digital Convergence
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• v.10 no.4
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• pp.257-263
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• 2012

Smart phones become popular all over the world recently. At the same time, demand of various additional services, such as SNS by utilizing low-cost reliable Wi-Fi network and position information, is expected to keep growing. In this paper, Implementation of SNS based on an Open Wi-Fi & Position Information was proposed. This service is achieved by constructing an Open Wi-Fi network based on a built AP access information database. And in order to provide durable connection in mobile environment, RSS detect AP switching module and mobile IP are utilized in the proposed service. Furthermore, with the utilization of GPS information of AP, AP providers could delivery various information such as advertisements, promotion events. In addition, it is possible for AP users to communicate with each other, thus a position information based SNS was also proposed in this paper.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.445-448
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• 2018

In this paper, we design microstrip antenna for GPS / WiFi for broadband mobile communication. The proposed antenna is designed to be used in the FR-4 (er = 4.3), the size is $40mm{\times}50mm$, and it can be used in the GPS frequency band of 1.6GHz and the WiFi frequency band of 5GHz. 2014, and the simulation result shows that the gain is 1.909dB at 1.6GHz and 4.607dB at 5GHz. The S-parameter also showed a result of less than -10dB (WSWR2: 1) in the desired frequency band. Recently, it is expected that GPS navigation system, which is widely used in smart phones and tablet PCs, can be easily and conveniently used by combining and applying GPS with WiFi.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.83-88
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• 2006

Many applications in the area of location-based services and personal navigation require nowadays the location determination of a user not only in outdoor environment but also indoor. To locate a person or object in a building, systems that use either infrared, ultrasonic or radio signals, and visible light for optical tracking have been developed. The use of WiFi for location determination has the advantage that no transmitters or receivers have to be installed in the building like in the case of infrared and ultrasonic based location systems. WiFi positioning technology adopts IEEE802.11x standard, by observing the radio signals from access points installed inside a building. These access points can be found nowadays in our daily environment, e.g. in many office buildings, public spaces and in urban areas. The principle of operation of location determination using WiFi signals is based on the measurement of the signal strengths to the surrounding available access points at a mobile terminal (e.g. PDA, notebook PC). An estimate of the location of the terminal is then obtained on the basis of these measurements and a signal propagation model inside the building. The signal propagation model can be obtained using simulations or with prior calibration measurements at known locations in an offline phase. The most common location determination approach is based on signal propagation patterns, namely WiFi fingerprinting. In this paper the underlying technology is briefly reviewed followed by an investigation of two WiFi positioning systems. Testing of the system is performed in two localization test beds, one at the Vienna University of Technology and the second at the Hong Kong Polytechnic University. First test showed that the trajectory of a moving user could be obtained with a standard deviation of about ${\pm}$ 3 m.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.8
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• pp.42-50
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• 2011

Recently, research activities on the future internet are being actively performed in foreign and domestic. In domestic, ETRI and 4 universities are focused on implementation of a testbed for research on the future internet named as 'FiRST(Future Internet Research for Sustainable Testbed)'. In the 'FiRST' project, 4 universities are performing a project in collaboration named as 'FiRST@PC' project that is for an implementation of the testbed using the programmable platform-based openflow switches. Currently, the research on the virtualization of the testbed is being performed that has a purpose for supporting an isolated network to individual researcher. In this paper, we implemented a traffic scheduler for providing QoS by using the programmable platform that performs a hardware-based packet processing and we are implemented a testbed using that traffic scheduler. We perform a performance evaluation of the traffic scheduler on the testbed. As a result, we show that the hardware-based NetFPGA scheduler can provide reliable and stable QoS to virtualized networks of the Future Internet Testbed.

• Journal of Korea Game Society
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• v.15 no.5
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• pp.119-130
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• 2015

In the recent gaming industry, the paradigm has been changed with upcoming core-platform as time goes by. Arcade, console, PC online and smart device platforms are representative ones. In recently, the platform is changed to multi-platform which connecting to smart device and other platforms. Besides, the multi-platform without PC is up-coming. This paper suggests that a kind of multi-platform which connecting from smart devices to arcade devices be aware of lack of continuous. It provides a new arcade gaming condition connecting to smart devices, then supplies online network conditions to the arcade gaming machine. The original arcade game was lack of continuous and the game platform was so simple, but now, it could be focused from players by connecting to smart devices to increase the gaming machines' continuity. Furthermore, Bluetooth communication module and wireless Wi-Fi communication module are used to adapt various communication environments. The Unity3D engine would make contents' expandability.

• Journal of Digital Convergence
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• v.12 no.4
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• pp.327-333
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• 2014

Recently, smartphone are increasing in Internet-enabled applications to install and delete benefits as well as internet through various interfaces such as 3G network, Wi-Fi, Wibro without the constraints of time and place. However, the prevalence of smartphones and the activity was generated from an existing PC smartphone security threats are causing a ripple in a society. In this paper, we serve live content services on the first and last content by creating an electronic signature is the signature of either the loss of any Content provided by both authentication and non-repudiation content protection scheme is proposed. The proposed method of secure smartphone users to download and install the content or an application for downloading content over the content for secure authentication.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1275-1280
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• 2018

We made a smartphone interlocking location tracking streetlight and remote display device to compensate the defect of real time identifiable CCTV streetlights and child safety notification applications. It controls brightness of LED by detecting the surrounding brightness and objects with ultrasonic sensor and illuminance senor. The CCTV receives the location of smartphone by Bluetooth and takes the target of the location. It realizes a wireless transmission system that the video is upload to the tablet PC via WiFi.