• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1138-1143
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• 2013

In this paper, we propose a smartphone application based on a wireless fidelity(WiFi) in order to control the charging of electric vehicle(EV) and monitor the charging status together with the vehicle history information. The driver obtains much information on vehicle status through a smartphone application which communicates with the electric vehicle supply equipment(EVSE) management server while the EV also communicates with the EVSE for the authentification through controller area network(CAN). We also implement the simulator for the EV charging control system to verify the functions of the proposed application where the simulator consists of an EV model, an EVSE, and a smartphone. It is shown by the simulator that the proposed smartphone application allows the driver to control and to monitor the charging process of an EV conveniently and, moreover, it can provide the driver with vehicle information stored in the EVSE management server.

• Journal of Advanced Navigation Technology
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• v.26 no.1
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• pp.1-8
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• 2022

Telemetry system is a system that measures and transmits status information in the aircraft to the ground. The data received from the ground is information for monitoring the state of the aircraft, and can be checked and analyzed in real time through the test program. Data processing test system for telemetry currently in operation is built to transmit data using wired communication and perform test. As smart devices become popular due to the continuous development of information and communication technology, wireless communication networks are becoming important, and technologies for improving performance are steadily being developed. In this paper, we suggests and builds data processing ground test system for telemetry using wireless communication(Wi-Fi) that can be checked through smart devices such as tablets, in order to break away from the existing method and apply future-oriented technology. Finally, the suggested test system performance was proved by testing in various environments by linking test equipment and test program.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.255-258
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• 2011

Wi-Fi is a rapidly spreading communications network with Smart phone's publication, the technology has become Ubiquitous-based core network which is connected to personal computers, laptops, and tablet PC. Wi-Fi can send currently a variety of data standard due to developed wireless LAN communications network. One of Wi-Fi standard protocols, which is IEEE 802.11n, use 2.4GHz and 5GHz band. 2.4GHz band is used for 802.11b/g protocol because wavelength is long, diffraction and receiving distance is enough to connect other device. 5GHz band has more available channels to use than 2.4GHz band, so there is no frequency interference of other wireless device such as Bluetooth, RFID. Moreover, there is low interference between channels due to small users in each bandwidth level. In the thesis, we are going to analyze 802.11a/b/g protocol which has used since the beginning of Wi-Fi protocol and 802.11n protocol which is used lately. Furthermore, we look into development and direction for standardization of the next generation wireless LANs which are 802.11ac and 802.11ad. In addition, we will consider for the security, vulnerabilities and its countermeasure in Wireless LAN.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.362-370
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• 2010

In this paper, a compact RF Front-end module for Wireless Fidelity(Wi-Fi) and Worldwide Interoperability for Microwave Access(WiMAX) applications is realized by low temperature co-fired ceramic(LTCC) technology. The RF Front-end module is composed of three LTCC band-pass filters, a Film Bulk Acoustic Resonator(FBAR) filter, fully embedded matching circuits, an SPDT switch for mode selection, an SPDT switch for Tx/Rx selection, and an SP4T switch for band selection. The parasitic elements of 0.2~0.3 pF are generated by the structure of stacking in the top pad pattern for DC block capacitor of SPDT switch for mode selection. These kinds of parasitic elements break the matching characteristic, and thus, the overall electrical performance of the module is degraded. In order to compensate it, we insert a parallel lumped-element inductor on capacitor pad pattern for DC block, so that we obtain the optimized performance of the RF Front-end module. The fabricated RF front-end module has 12 layers including three inner grounds and it occupies less than $6.0mm{\times}6.0mm{\times}0.728mm$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4884-4890
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• 2015

These days most of people possesses an average of one to two mobile devices in the world and a wireless network market is gradually expanding. Wi-Fi preference are increasing in accordance with the use growth of mobile devices. A number of areas such as public agencies, health care, education, learning, and content, manufacturing, retail create new values based on Wi-Fi, and the global network is built and provides complex services. However, There exist some attacks and vulnerabilities like wireless radio device identifier vulnerability, illegal use of network resources through the MAC forgery, wireless authentication key cracking, unauthorized AP / devices attack in the next generation radio network environment. In addition, advanced security technology research, such as authentication Advancement and high-speed secure connection is not nearly progress. Therefore, this paper designed a secure communication system for message protection in next-generation wireless network environments by device identification and, designing content classification and storage protocols. The proposed protocol analyzed safeties with respect to the occurring vulnerability and the securities by comparing and analyzing the existing password techniques in the existing wireless network environment. It is slower 0.72 times than existing cypher system, WPA2-PSK, but enforces the stability in security side.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2118-2135
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• 2012

With the rapid development of heterogeneous emerging wireless technologies and numerous types of mobile devices, the need to support robust mobile video streaming based on the seamless handover in Future Internet is growing. To support the seamless handover, several IP-based mobility management protocols such as Mobile IPv6 (MIPv6), fast handover for the MIPv6 (FMIPv6), Hierarchical MIPv6 (HMIPv6) and Proxy Mobile IPv6 (PMIPv6) were developed. However, MIPv6 depreciates the Quality-of-Service (QoS) and FMIPv6 is not robust for the video services in heterogeneous emerging wireless networks when the Mobile Node (MN) may move to another visited network in contrast with its anticipation. In Future Internet, the possibility of mobile video service failure is more increased because mobile users consisting of multiple wireless network interfaces (WNICs) can frequently change the access networks according to their mobility in heterogeneous wireless access networks such as 3Generation (3G), Wireless Fidelity (Wi-Fi), Worldwide Interoperability for Microwave Access (WiMax) and Bluetooth co-existed. And in this environment, seamless mobility is coupled according to user preferences, enabling mobile users to be "Always Best Connected" (ABC) so that Quality of Experience is optimised and maintained. Even though HMIPv6 and PMIPv6 are proposed for the location management, handover latency enhancement, they still have limit of local mobility region. In this paper, we propose a robust mobile video streaming in Heterogeneous Emerging Wireless Systems. In the proposed scheme, the MN selects the best-according to an appropriate metric-wireless technology for a robust video streaming service among all wireless technologies by reducing the handover latency and initiation time when handover may fail. Through performance evaluation, we show that our scheme provides more robust mechanism than other schemes.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.127-128
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• 2020

본 논문에서는 무선 통신(Wi-Fi)과 FireBase를 활용해 화재 발생을 알려 다수의 사람들이 대피 할 수 있는 시스템이다. 이 시스템은 아두이노를 기반으로 가스·불꽃·온도센서로 화재를 감지하고, 화재를 감지하면 무선 통신을 이용해 서버와 파이어 베이스로 전송한다. 서버로 전송된 데이터는 사용자들에게 어플리케이션의 푸시 기능으로 화재 발생 알림을 전송하고, 파이어 베이스로 전송된 데이터는 어플리케이션에서 대피경로를 알려주어 신속한 대피를 할 수 있게 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.327-330
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• 2012

In the rapid growth of cities, road has heavy traffic and many buildings are under constructions. These kinds of environments make more difficulty for a person who is visually handicapped to walk comfortable. To alleviate the problem, we introduce Android based Portable Navigation System to help walking for Visually Impaired Person. It follows, service center give instant real time monitoring to visually impaired person for their convenient by this system. Android based Portable Navigation System has GPS, Camera, Audio and WI-FI(wireless fidelity) available. It means that GPS location and Camera image information can be sent to service center by WI-FI network. To be specific, transmitted GPS location information enables service center to figure out the visually impaired person's whereabouts and mark the location on the map. By delivered Camera image information, service center monitors the visually impaired person's view. Also, they can offer live guidance to visually impaired person by equipped Audio with live talking. To sum up, Android based Portable Navigation System is a specialized navigation system that gives practical effect to realize more comfortable walking for visually impaired person.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2702-2707
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• 2012

In the rapid growth of cities, road has heavy traffic and many buildings are under constructions. These kinds of environments make more difficulty for a person who is visually handicapped to walk comfortable. To alleviate the problem, we introduce Navigation System to help walking for Visually Impaired Person. It follows, service center give instant real time monitoring to visually impaired person for their convenient by this system. This Navigation System has GPS, Camera, Audio and Wi-Fi(wireless fidelity) available. It means that GPS location and Camera image information can be sent to service center by Wi-Fi network. To be specific, transmitted GPS location information enables service center to figure out the visually impaired person's whereabouts and mark the location on the map. By delivered Camera image information, service center monitors the visually impaired person's view. Also, they can offer live guidance to visually impaired person by equipped Audio with live talking. To sum up, Android based Portable Navigation System is a specialized navigation system that gives practical effect to realize more comfortable walking for visually impaired person.

• Journal of the Semiconductor & Display Technology
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• v.22 no.2
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• pp.50-55
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• 2023

Due to the unavailability of global positioning system (GPS) indoors, various indoor pedestrian positioning methods have been designed to estimate the position of the user using received signal strength (RSS) measurements from radio beacons, such as wireless fidelity (WiFi) access points and Bluetooth low energy (BLE) beacons. In indoor environments, radio-frequency (RF) signals are unpredictable and change over space and time because of multipath associated with reflection and refraction, shadow fading caused by obstacles, and interference among different devices using the same frequencies. Therefore, the outliers in the positional information obtained from the indoor positioning method based on RSS measurements occur often. For this reason, the performance of the positioning method can be degraded by the characteristics of the RF signal. To resolve this issue, a map-matching (MM) algorithm based on maximum probability (MP) estimation is applied to the indoor positioning method in this study. The MM algorithm locates the aberrant position of the user estimated by the positioning method within the limits of the adjacent pedestrian passages. Empirical experiments show that the positioning method can achieve higher positioning accuracy by leveraging the MM algorithm.