• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.1-5
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• 2015

Recently, RF energy harvesting technology is a promising technology for small-size IoT(Internet of Things) devices such as sensor to resolve battery scarcity problem. When applied to existing cognitive radio networks, this technology can be expected to increase network throughput through the increase of cognitive user's operating time. This paper proposes a optimal channel-selection policy for RF energy harvesting CR networks model where cognitive users in harvesting zone harvest ambient RF energy from transmission by nearby active primary users and the others in non-harvesting zone choose the channel and communicate with their receiver. We consider that primary users and secondary users are distributed as Poisson point processes and contact with their intended receivers at fixed distances. Finally we can derive the optimal frame duration, transmission power and density of secondary user from the proposed model that can maximize the secondary users's throughput under the given several conditions and suggest future directions of research.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.8
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• pp.958-966
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• 2012

This paper presents a compact bluetooth/WiFi dual-mode dual-band RF front-end module(FEM) is realized by low temperature co-fired ceramic(LTCC) technology. The proposed RF front-end module consists of a diplexer, baluns in the LTCC substrate, and an SPDT switch, an SP3T switch on the LTCC substrate. In order to reduce the module size and increase integration level, the proposed diplexer and balun are designed using LC lumped elements. The parasitic elements caused by coupling effect between metal pattern layers and ground plane layer are considered during the design. The fabricated dual-mode RF front-end module has 13 pattern layers including three inner ground layers and it occupies less than $3.0mm{\times}3.7mm{\times}0.66mm$.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.87-93
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• 2016

In this paper, we propose a RF energy harvesting based routing protocol in mobile ad-hoc wireless sensor networks. The main features and contributions of the proposed routing protocol are as follows. First, establishment of routing route based on both remaining energy of mobile sensor nodes and RF energy harvesting. Second, establishment of routing route by considering availability and stability of route based on energy of mobile sensor nodes to increase lifetime of networks and route. The performance evaluation of the proposed routing protocol using OPNET shows that the routing method considering both route availability and route stability based on RF energy harvesting can increase efficiently route lifetime.

• Journal of Advanced Navigation Technology
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• v.6 no.4
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• pp.296-305
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• 2002

This paper suggests the parameters of the requirement conditions of minimum performance for a RF transceiver system design from the specifications of IEEE Std 802.11b and IEEE Std 802.11a. It has yielded the requirement conditions of minimum performance in the design process due to these parameters. A RF transceiver system is simulated by using Agilent ADS(Advanced Design System) after selecting the components of optimal conditions to fabricate the RF transceiver system. The results of both the analysis and the simulation will be used for a real wireless LAN design.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.777-783
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• 2009

In this paper, we implemented a wireless power transmission system at 2.45 GHz. The transmission power is limited within 20 dBm according to the ISM frequency regulations. We used two zero-bias Schottky diode and optimized the RF-DC converter for working a clock at 80 cm distance using a receiver with a single antenna and an Rf-DC converter to reduce parts and cost compared to previously reported literatures.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.269-273
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• 2013

This paper analyzed a potential interference of electric equipments on radio service below 30MHz through an experiment with a PDP(Plasma Display Panel) TV and a RF(Radio Frequency) light bulb in an anechoic chamber. The radiation levels of the PDP TV and the RF light bulb are measured and a combined interference is calculated on the basis of the experimental value. As a result, the combined interference signal level is increased according to the number of interferer. The possibility of a potential interference from electric equipments on radio service below 30MHz is realized through comparison between the measured radiation value of electric equipments and the CISPR(International Special Committee on Radio Interference) 11 limit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.6
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• pp.43-48
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• 2006

In this paper, the rectenna converting 2.45[GHz] microwave into DC power is designed and fabricated for wireless power transmission using microwave and the methode for impedance matching and tuning are proposed in order to maximize RF-DC conversion efficiency. The fabricated rectenna can be easily tuned by using a broad open stub and has the RF-DC conversion efficiency up to 59[%] when the 5[dBm] input power is applied. The 2.2[V], 1.5[mW] DC level, in the 1[m] distance between the transmitter and the receiver can be obtained and this value is avaliable in the small power digital system.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.55-59
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• 2016

Conventional RF energy harvesting systems can harvest energy and decode information from same source as an Hybirid-AP (H-AP). However, harvesting efficiency is seriously dependent on distance between users and H-AP. Therefore, in this paper, we proposed a transmission model for RF harvesting consisting of information and power source separately called Decoupled RF Energy harvesting networks. Main purpose of this paper is to maximize energy efficiency under various constraints of transmit power from H-AP and power beacon (PB), minimum quality of service and quality of harvested power of each users. To measure proposed model's performance, we proposed optimal time scheduling algorithms for energy efficiency (EE) maximization using Lagrangian dual decomposition theory that locally maximizes the EE by obtaining suboptimal values of three arguments : transmit power of H-AP, transmit power of PB, frame splitting factor. Experiment results show that the proposed energy-efficient algorithms converge within a few iterations with its optimality and greatly improve the EE compared to that of baseline schemes.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.2
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• pp.21-28
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• 2010

Air pollution monitoring has attracted a lot of interests because it affects directly to the human life quality. The most of the current air pollution monitoring stations use the expensive and bulky instruments and are only installed in the specific area. Therefore, it is difficult to install them to as many places as people need. In this work, we constructed a low price and small size Radio Frequency(RF) sensor system to solve this problem. This system also had the measurement range similar to the ones used in the air pollution forecast systems. This system had the sensor unit to measure the air quality, the central processing unit for air quality data acquisition, the power unit to supply the power to every units, and the RF unit for the wireless transmission and reception of the data. This system was easy to install in the field. We also added a GPS unit to track the position of the RF-sensor in real time by wireless communication. For the various measurements of the air pollution, we used CO, $O_3$, $NO_2$ sensors as gas sensors and also installed a dust sensor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.41-44
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• 2004

A RFID(Radio Frequency IDentification) system Is a kind of Radio Frequency Communication System and a branch of Automatic Data Collection System. The RFID System is composed of RF Tag(or Transponder) and RFID Reader(controller). This paper deal with Wireless communications that acquired RF Tag ID by RFID reader, and then target system will transmit Tag ID to RFID Server through the internet using Wireless LAN. The RFID system of Todays are commonly used by a wired RFID system. In this system uses commonly used Wireless LAN, and then we can connect the internet if we have a AP(Wireless Lan Access Point). Internet connection can make a transmission of RF Tag ID, and can make a reception of returning data that are images or information.