• Journal of the Korean Geographical Society
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• v.48 no.2
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• pp.259-271
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• 2013

This paper addresses the efficient facility placements to adopt a super WiFi network, taking significant considerations as the next generation 'information highway'. Since the super WiFi has a wider geographic coverage by utilizing the white spaces of TV broadcasting which are empty and available frequencies for the wireless communications, it would play an important role in releasing digital divide of the internet access for low populated or mountainous areas. The purpose of this paper is to explore systematic and efficient spatial plans for the super WiFi. For doing this, we applied optimal location covering models to Gurye-gun, Jeonlanamdo. From the application, we presented optimal locations for super WiFi facilities and significant analytical results, such as the tradeoff between the number of facilities and coverage and marginal coverage for establishing super WiFi network. The results of this research would be usefully utilized for decision makers who wish to adopt a super WiFi, to extend wireless networks in a city or build a regional infrastructure of wireless facilities.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1373-1392
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• 2017

WiFi Direct (WD) is a state of the art technology for a Device-to-Device (D2D) communication in 802.11 networks. The performance of the WD system can be significantly affected by some key factors such as the type of application, specifications of MAC and PHY layer parameters, and surrounding environment etc. It is, therefore, important to develop a system model that takes these factors into account. In this paper, we focus on investigating the design parameters of the PHY layer that could maximize the efficiency of the WD 802.11 system. For this purpose, a basic theoretical model is formulated for a WD network under a 2x2 Multiple In Multiple Out (MIMO) TGn channel B model. The design level parameters such as input symbol rate and antenna spacing, as well as the effects of the environment, are thoroughly examined in terms of path gain, spectral density, outage probability and Packet Error Rate (PER). Thereafter, a novel adaptive algorithm is proposed to choose optimal parameters in accordance with the Quality of Experience (QoE) for a targeted application. The simulation results show that the proposed method outperforms the standard method thereby achieving an optimal performance in an adaptive manner.

• Journal of Information Technology Applications and Management
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• v.26 no.5
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• pp.41-56
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• 2019

Recently great loss of life and property is occurring because of fire, natural disaster, earth quake, tsunami and so on. People spend 80~90% of their time indoor environment like office, supermarket, campus. Therefore Indoor navigation and guidelines system became so essential for most of all. Incase of emergency we must be careful earlier, in such a cases 5G kind of new technology may also cannot work. So immediate action and quick routing notification for guidelines and protection is the most. Considering this issue We proposed indoor evacuating guidance system based on microcontroller Wi-Fi board for Indoor APP using mobile. Focusing various kind of technology like, ok google, voice search APP we purposed node architecture based system. When we listen fire alarm while living inside the room. Then to be safe we connect with server and start Arduino UNO+IoT ESP8266 Wi-Fi shield version1-IoT module to store data in MySQL DB server. We make application to escape out from the building up-to the three exits giving information from source point to destination. Our program can send information to the users emergency location and situations. For this when the user get sound or vibration in their mobile device it indicate fire out near by. At that time we update message from Arduino to DB server for the fixed current position inside the building which give routing signal for that fire out location by changing values from 0 to 1. We have user in point 10 where user is near by. Later we detect Wi-Fi signal form Nodemcu as room of each floor and try to connect with user. Main purpose of this paper is to save life of people in short time and find out the shortest path up to nearest exits in the time of emergencies and rescue them.

• Journal of Digital Contents Society
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• v.18 no.5
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• pp.895-904
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• 2017

In this paper, we propose an IoT based smart outlet system for one-person household with electric safety, electric energy consumption management and transmission of messages to the reserved contacts by connecting the emergency network. The proposed smart outlet system is implemented by parsing packet data and protocol between server, module, application and WiFi AP receiver. The WiFi AP built for communication can be used not only for the outlet but also for the gas barrier, the door lock and the like. In addition, the proposed method can provide the remote monitoring function by receiving the amount of power of the receptacle received through the AC current sensor (SCT-013) in real time. The smart outlet system is expected to be capable of automatically shutting off the power in case of emergency through automatic power use analysis in addition to the standby power cutoff function.

• Journal of the Korea Society for Simulation
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• v.25 no.2
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• pp.21-29
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• 2016

Indoor location system has been used Wi-Fi to get a location. After the development of BLE(Bluetooth Low Energy), the interest in the method of a indoor positioning had been move on. It has more advantages than using Wi-Fi. Easy installation, low power consumption, low signal interference and changeable setting(Advertising interval, tx power, etc.). These things can improve efficiency or accuracy in a indoor positioning system. For this reason, recent indoor positioning system uses BLE rather than Wi-Fi. Accordingly, error factors of BLE beacon based indoor positioning should be studying for high accuracy of indoor positioning. In this research, set up few experiment scenarios and keep a close watch on how technological, environmental factor is affecting positioning accuracy. When a application uses largest signal strength to get the indoor location, the mean error of experimental results was decreased compare to using received signal strength in real-time. The result was same when the application applied average and standard deviation to get the indoor location. Changing advertising interval had an effect on the mean error of indoor positioning. Short advertising interval makes the lower mean error than large advertising interval.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.11
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• pp.1018-1026
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• 2012

This paper presents a developing method of smart fingerprint recognition system. First, we design a hardware configuration circuit using a 32bit Risc CPU, a fingerprint sensor, a LCD, and a WiFi communication chip to realize the smart fingerprint recognition systems. It is necessary to develop a JNI (Java Native Interface) library and a device drive program of fingerprint sense to develop application program of fingerprint recognition system with Android platform. Thus second, we develop a device drive and a JNI program. And we also develop an application program of fingerprint recognition systems using developed JNI library. Finally test results are presented to illustrate the performance of the developed smart fingerprint recognition system.

• Korean Journal of Agricultural Science
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• v.38 no.4
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• pp.753-759
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• 2011

Protected crop production has been popular in Korea as well as in other countries. Intensive and continuous monitoring and control of the environment, which is labor- and time-consuming, is critical for stable crop productivity and profitability, otherwise damage could be happened due to unfavorable ambient and soil conditions. In the study, potential utilization of smartphone and remote access application in protected crop production environment was investigated. Tested available remote access applications provided functions of mouse click (left and right buttons), zooming in and out, and screen size and color resolution control. Wi-Fi data communication speeds were affected by signal intensity and user place. Data speeds at high (> -55 dBm), medium (-70~-56 dBm), and low (< -71 dBm) signal intensity levels were statistically different (${\alpha}=0.05$). Means of data communication speed were 6.642, 4.923, and 2.906 Mbps at hot spot, home, and office, respectively, and the differences were significant at a 0.05 level. Smart phone and remote access application were applied successfully to remote monitoring (inside temperature and humidity, and outside precipitation, temperature, and humidity) and control (window and light on/off) of green house environment. Response times for monitoring and control were less than 1 s at all places for high signal intensity (> -55 dBm), but they were increased to 1 ~ 10 s at home and office and to 10 ~ 30 s at hot spot for low signal intensity (< -71 dBm) for Wi-Fi. Results of the study would provide useful information for farmers to apply these techniques for their crop production.

• 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.

• Proceedings of the Korean Society of Computer Information Conference
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• 2011.06a
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• pp.191-195
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• 2011

Smart Phone의 OS로 많이 사용하는 Android/Windows Mobile Smart Phone의 사용이 급격히 증가하고 있다. 무료 WiFi Zone과 인터넷 사용에 대한 취약점이 존재한다. Mobile Forensic의 증거 자료를 추출하는 방법은 SYN, JTAG, Revolving 방법이 있지만, 기존 휴대폰과 달리 Smart Phone은 OS와 구조, 사용방식과 기술의 차이로 인한 Mobile Forensic 연구 방법도 달라야 한다. 본 논문에서는 Smart Phone에서는 많이 사용되는 Windows Mobile/Android Smart Phone의 OS와 구조 차이를 분석한 데이터 백업과 스펙 분석 및 증거자료 분석을 한다. 또한 무료 WiFi Zone을 통한 인터넷 사용시에 취약점을 분석한다. 그리고 Android/Windows Mobile Smart Phone의 Forensic 자료를 생성하여 증거를 추출하고, Mobile Forensic 보고서를 생성한다. 본 연구를 통하여 Mobile Forensic의 기술 발전에 초석을 제공할 것이다.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.41-47
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• 2013

This letter describes a dual-band compact monopole antenna with two branches for Wi-Fi applications. The proposed antenna is based on a planar monopole design, and composed of two branches of radiating patches for dual-band operation. The ground size of the antenna matches the ground size of a typical hand-held cellular phone for improved compatibility with mobile phone printed circuit boards. The antenna is designed using a simulator and fabricated with optimized parameters. The fabricated antenna is measured at the lower and higher operating frequencies, and the return loss coefficient, gain, and radiation patterns are determined.