• Electronics and Telecommunications Trends
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• v.21 no.3 s.99
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• pp.1-10
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• 2006

차세대 이동통신에 의한 새로운 정보통신 환경 실현은 21세기의 산업구조에도 막대한 영향을 주어서 대변혁을 가져올 것이다. 4세대 이동통신의 실현에 의한 정보통신환경의 Broadband화, Ubiquitous화, Mobile & Wireless화에 의해 주요한 산업으로 크게 확대되고, 융합.발전할 것으로 기대되고 있다. IMT-Advanced 이동통신 기술은 고속이동 환경에서 최대 100Mbps, 고정 또는 저속이동 환경에서 최대 1Gbps의 데이터전송속도로 비대칭/대칭적 패킷 서비스와 방송 서비스를 포함한 다양한 서비스를 IP기반으로 통합 제공하는 기술을 의미하며, IMT-Advanced 시스템뿐만 아니라 다양한 무선통신 시스템과 통합되는 형태로 실현될 것으로 예상된다. 본 고에서는 차세대 이동통신기술 동향과 국내외 개발 동향, 표준화 동향 등을 간략히 살펴보고자 한다. 특히, 차세대 이동통신 기술은 셀룰러 이동통신, 차세대 WLAN, 차세대 WPAN, SDR 등을 중심으로 살펴보고자 한다.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.8
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• pp.742-747
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• 2004

Outdoors we can easily acquire our accurate location by GPS. However, the GPS signal can't be acquired indoors because of its weak signal power level. Adequate positioning method is demanded for many indoor positioning applications. At present, wireless local area network (WLAN) is widely installed in various areas such as airport, campus, and park. This paper proposes a positioning algorithm using WLAN signal strength to provide the position of the WLAN user indoors. There are two methods for WLAN based positioning, the signal propagation method uses signal strength model over space and the empirical method uses RF power propagation database. The proposed method uses the probability distribution of the power propagation and the maximum likelihood estimation (MLE) algorithm based on power strength DB. Test results show that the proposed method can provide reasonably accurate position information.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.1061-1062
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• 2011

21 세기의 자동차 IT 융합 기술은 이동수단의 차량 운송 기술을 넘어 IT 첨단화 기술로 성장하고 있으며, 전장기술과 함께 정보통신 IT 분야의 핵심기술로 자리잡고 있다. 특히, 스마트-폰과 연계한 이동통신기술의 발달로 유,무선통신 및 인터넷을 결합한 유비쿼터스 컴퓨팅 기술이 급속히 발전하고 있음에 따라 Automotive-IT 첨단기술은 시간과 장소의 한계를 극복하여 언제 어디서나 자동차내에서 또는 통합관제 운용시스템을 통하여 운행정보와 ITS 지능형자동차 기술로 발전시킬 수 있는 것이다. 본 논문에서는 자동차 응용기술을 통하여 IT 융,복합기술로 급성장하고 있는 자동차 Automotive-IT 응용기술에 대한 향후 연구기술 방안을 제안한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.485-494
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• 1998

Communication network numbers are used in classifying each kind of network, identifying the communication companies and choosing services that are supplied by the companies. In the present, a new numbering system is needed to distinguish a new additional communication network. However the present numbering system of domestic communication network has some problems such as exhaustion of network number, excessive local numbers, and so forth So, in this thesis we call the wire and the wireless telephone network, the pager network and the personal number as communication networks, and consider the present condition and problems of our country, Korea, and foreign countries. Then we propose the efficient numbering plan. Firstly, the present 10 numbering systems that are distributed, such as communication networking number $\ulcorner$01X$\lrcorner$ are diminished into 5 communication network numbers that have same quality. Secondly, subscriber numbers are united to 8 digit and 144 area codes are made into widened 5 area codes. Thirdly, the personal numbering services are cross-distributed by century. And we examine the technical convening plan and the legal converting plan and investigate expecting efficiency of proposed numbering system. If this numbering plan is executed, subscriber's number on communication networks are unified at 8 digits, 5 reserve numbers are secured in exhausted communication network number of $\ulcorner$01X$\lrcorner$, and they can distribute subscriber numbers over twice as much. In addition, number acceptability is enlarged from 237,600 thousands to 400,000 thousands. Personal number can be classified at not only century but also a decade. Accordingly, acceptable numbers are increased two folds enough to provide unification and population increase. We were able to confirm all the efficiencies.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.129-134
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• 2018

Research on the technique for estimating the indoor position has been actively carried out. In particular, the WiFi fingerprint method, which does not require any additional infrastructure, is being partially used because of its high economic efficiency. The KNN method which estimates similar points to the corresponding points by comparing intensity information of the WLAN reception signal measured at various points in advance with intensity information measured at a specific point in the future is simple but has a good performance. However, in the conventional KNN scheme, since the number K of average candidate positions is constant, there is a problem that the position estimation error is not optimized according to a specific point. In this paper, we proposed an algorithm that adaptively changes the K value for each point and applied it to experimental data and evaluated its performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.553-562
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• 2007

In this paper, we designed and implemented the system for telemetering ELF(Extremely Low Frequency) magnetic field intensity. The magnetic field measurement system used a 3-axis magnetic field sensor to measure the magnetic field with isotropy and the equalizer to compensate the frequency characteristic in band. By multiplexing three output signals of the magnetic field sensor in time domain, we got the uniform gain and frequency characteristic among three axes. This system was designed that the magnetic field measurement level range was $0.01{\sim}10.0\;uT$ and the measurement frequency band was $40{\sim}180\;Hz$. The control system would access to the magnetic field measurement system with RF and the maximum access distance was 1.0 km. We confirmed that the measurement level error of the fabricated system was within 5 %. The fabricated system was installed to a golf practice range where a high voltage power transmission line was crossed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.339-346
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• 2011

In the existing RF communication based WPAN environment, a lowering of battery span and interference problem among sensors occur because the value of output is set and transmitted steadily when the system on sensor is initialized. Therefore, this paper proposes a framework and a transmit method with low power which decreases the electricity consumption by properly controling transmit power of opponent by received signal strength indicator(RSSI) of each sensor. The system proposes a power-lowering method by controling transmit power properly by the transmit intensity of the connected sensor after being affected by the transmit intensity of surrounded sensor. The framework that is proposed in this paper includes data transmit module, transmit power manager module, transmit power searching module, signal transmit module, and signal receiving module.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.149-156
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• 2014

Floor number determination has attracted considerable attention because many applications require accurate floor number information for providing better localization services in multistory buildings. This paper describes a Wi-Fi-based, low-complexity floor number determination method for multistory buildings. In our scheme, with the exception of floor ID and received signal strength of each WAP, detailed information on the wireless access point (WAP) coordinates is not needed. The multi-wall-floor model is used for the simulation and analysis. The simulation results show that the floor determination accuracy is nearly 100 given an adequate deployment density of WAPs on each floor. The results also show that the proposed method provides a good estimate of floor number even when only a few WAPs are implemented on each floor. Specifically, the proposed method can work under extreme conditions, i.e., where there are no WAPs on a floor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.5
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• pp.382-390
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• 2017

In this paper, we consider particular exposure scenarios to evaluate human effects for inductive commercial wireless charging device operating at low frequency. The coil used in this study is the A10 model in Qi standard proposed by WPC(Wireless Power Consortium), and input power is 5 W to the operating frequency of 155 kHz. In perfectly aligned condition, the max leakage magnetic field is $257.58{\mu}T$ which is obtained at the side of the device, and it is exceeded about 7.4 times of the ICNIRP 1998 reference level. The SAR is evaluated with homogeneous phantom which has electric constants of wet skin. The max value of the SAR is $134.47{\mu}W/kg$ which is obtained at the side of the device also, and it is much lower than the international guidelines. Especially, it showed higher SAR values in case of misalignment condition, so we will need to consider the misalignment condition importantly when we evaluate human effects for wireless power transfer system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.239-241
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• 2011

Recently, studies on the indoor positioning system in application of wireless AP have been actively going on. The indoor wireless positioning system can be classified into several types according to the positioning techniques. Among them, the fingerprint technique is a technique that establishes the radio map by collecting MAC information of AP and RSSI (Received Signal Strength Indication) before executing positioning and then determines the position in comparison with the information of AP collected during the course of positioning. In the traditional fingerprint techniques, they control and manage by installing APs that are utilized for positioning. However, in case of specific indoors, the management can be done by installing a small number of APs but, in case of wide outdoors, it's practically impossible to install and manage equipments for positioning. In order to solve such problem, there is an improved fingerprint technique that utilizes the APs that are already scattered around. This technique will allow positioning without additional cost, but even the improved fingerprint positioning technique may incur dropped accuracy as well due to wide fluctuation of the AP information. In this paper, the traditional fingerprint technique and the improved fingerprint technique are explained in comparison, and we will compares difference in performance with the proposed WPS_WS (Wi-Fi Positioning System_Weak Signal) technique.