• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.925-928
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• 2013

In this paper, we propose a relay-based wireless power transmission scheme in order to solve the problems of an existing wired power transmission for energy harvesting system. The proposed scheme can be transferred electromagnetic induction-based wireless power transmission by placing a 4-way coils in the energy block. We confirm the reliability of the electricity transmission through the relay control algorithm. Consequently, the proposed scheme can extend the transmit receive paths of transmission power.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.2
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• pp.97-104
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• 2005

Usually, propagation attenuation of millimeter wave occurs by rainfall, snowfall, temperature, effect of pressure of air. In 60GHz wave band wireless communication network, temperature change becomes big factor of propagation loss department. Also, temperature change causes disturbance of 60GHz frequency at transceiver. In this study, we used 60GHz transceiver and found propagation loss of wireless path and operating frequency disturbance characteristics. In transceiver that there is no temperature compensated device, operating frequency of TX changed by 60.865GHz at temperature of $-5^{\circ}C$, and appeared by 60.730GHz when is $50^{\circ}C$. Therefore, operating frequency change width by temperature change are about 100MHz, greatly. But, in transceiver that there is temperature compensated device, operating frequency of TX changed by 60.830GHz at temperature of $-5^{\circ}C$, and appeared by 60.710GHz when is $50^{\circ}C$. Therefore, operating frequency change width by temperature change are about 20MHz. According to these result, we constructed between buildings examination wireless site for point to point wireless communication using 60GHz band transceivers who have do temperature compensated device, and investigated data transmission characteristics about ambient temperature change. Therefore, if use transceiver that have temperature compensated device, may overcome the wireless transmission error in 60GHz band wireless communication LAN networks despite of ambient temperature change.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.207-214
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• 2019

A large-capacity wireless power system is a technology that transmits electric power of kW or more in a noncontact type. Electric cars, electric buses, and electric railways. In order to increase the power transmission efficiency, a resonance method using a frequency of kHz is applied and the efficiency is 80 ~ 90%. In this case, the loss is 10 ~ 20% other than efficiency, and corresponds to several hundreds of W to several kW in kW class wireless power transmission. 35 kW wireless feed system environment, and induced current in the nearby conductive part was measured. As a result of analysis, it was confirmed that induction phenomenon is higher as the loop configuration of the conductive part per area is dense. The increase of the induced current in the mesh loop is characterized by the density of the nearby conductive part having a permeability per unit area. The concentration of the magnetic field by the permeability is increased and the induction phenomenon causing the induction current is increased. It was confirmed that induction phenomenon increases by about 2.7 times when 9 times dense structure is formed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.154-157
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• 2004

A realization for the wireless transmission system on the Un image using embedded server is presented on the paper to be simply to omni-direction data acquisition. The embedded system is composed of the image data acquisition which has CMOS sensor and lame grabber, the embedded server that takes the wireless LAN target board, and client part that is monitoring the image from the embedded server. The experiment result is average 12.7fps in 8bit on the 320$\times$240, 4:2:2 YCbCr. The system enable images transmission to be soft . monitoring.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.77-80
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• 2005

Wireless sensor networks(WSN) technology has various applications such as surveillance and information gathering in the uncontrollable area of human. One of major issues in WSN is the research for reducing the energy consumption and reliability of data. A system with forward error correction(FEC) can provide an objective reliability while using less transmission power than a system without FEC. In this paper, we propose to use LDPC codes of various code rate(0.53, 0.81, 0.91) for FEC for WSN. Also, we considered node-to-node interference in addition to AWGN channel. The proposed system has not only high reliable data transmission at low SNR, but also reduced transmission power usage.

• Journal of Korea Multimedia Society
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• v.10 no.6
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• pp.745-753
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• 2007

The wireless medium is known to be time-varying which could affect and result to a poor network's performance. As a solution, an opportunistic scheduling and power control algorithm based on IEEE 802.11 MAC protocol is proposed in this paper. The algorithm opportunistically exploits the channel condition for better network performance. Convex optimization problems were also formulated i.e. the overall transmission power of the system is minimized and the "net-utility" of he system is maximized. We have proven that an optimal transmission power vector may exist, satisfying the maximum power and SINR constraints at all receivers, thereby minimizing overall transmission power and maximizing net-utility of the system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6A
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• pp.803-819
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• 1999

We introduces a wireless multimedia CDMA system configuring multiple transmission links between a user and radio ports. We propose a centralized reservation access control scheme with transmission scheduling and dynamic allocation (CRMA/TSDA) to support the diverse multimedia traffic in the introduced CDMA system. We propose two types of transmission allocation algorithms: slot and link allocation algorithms with local information and global information. The transmission allocation algorithm proposed in this paper allocates a set of ports configuring multiple radio links and transmission slot/power to each of scheduled transmission requests. We perform simulations for the proposed system and algorithms. Through the simulation, we show that the performance of the algorithm with local information stands comparison with that of the quasi-optimum algorithm with global information. Also, the two algorithms in the system has shown to have better performance than the conventional CDMA system with a distributed random transmission method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.1-9
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• 2011

Nowadays it is necessary to replace electrical wires with another intelligent connection method because the consumers, who have much experience with mobile smart devices, are expecting easier and smarter connectivity in their home electronics such as wireless linking. In this paper a bidirectional CEC control scheme is newly proposed to expand the controllability from one to two way in a millimeter band image transmission system because two degree of freedom controllability presents more intelligent convenience in HDMI interface systems. Experimental study shows the feasibility of the proposed system as an advanced image transmission solution in millimeter band including an intelligent 2 DOF CEC interface with the performance result of 3.0 Gbps transmission band for 1080p full-HD image steaming.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.3
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• pp.497-506
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• 2024

In this paper, medium-power wireless power transmission is implemented using the commercial power frequency (60 Hz). Since general magnetic induction wireless power transmission devices use more than several tens of kHz, the commercial power frequency (60 Hz) cannot be used as is. Therefore an AC/DC converter is used to convert the 60 Hz power frequency into DC, and a high-frequency power amplifier is used to convert DC into several tens of kHz. In magnetic induction wireless power transmission, the AC/DC converter and high-frequency power amplifier are removed, and a extremely low frequency wireless power transmission(ELF-WPT) system using commercial frequency consisting of only transmitting resonance tank, transmitting coil, receiving resonance tank, and receiving coil is implemented, and verified through wireless power transmission experiments.

• Journal of IKEEE
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• v.16 no.3
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• pp.235-243
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• 2012

In this study, we developed two legged multi-joint robot by using wireless servo motor that was applied by wireless sensor network technology, which is widely used recently, and performed an experiment of walking method of two legged multi-joint robot. We constructed the star network with servo motors which were used at each joint of two-legged robot. And we designed the robot for operation by transmission of joint control signal from main control system or by transmission of the status of each joint to the main control system, so it operates with continuously checking the status of joints at same time. We developed the humanoid robot by using wireless digital servo motor which is different from existing servo motor control system, and controlled it by transmitting the information of angles and speeds of robot joints to the motor(node) as a feedback through main control system after connecting power and setting up the IDs to each joint. We solved noisy problem generated from wire and wire length to connection point of the control device by construction of the wireless network instead of using existing control method of wiring, and also solved problem of poor real time response to gait motion by controlling the position with continuous transmission of control signals to each joint. And we found that the effective control of robot is able by performing the simulation on walking motion in advance with the developed control algorithm which was downloaded into installed memory. Also we performed the stable walking with two-legged robot by attaching pressure sensor to robot sole. And we examined the robot gait operated by application of calculated algorithm on robot movement to each joint. In this study, we studied the method of controlling robot gait motion by using wireless servo motors and measured the torque applied to each joint, and found that the developed wireless servo motor by ZigBee sensor network offers easier control of two legged robot gait and better circuit configuration of it than the existing wired control system could do.