• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.11B
• /
• pp.1389-1393
• /
• 2011

In this paper, we implement the VLC system based on CAN communication which is usually used in car, plane, ship, product line control system, medical device and industrial device. We implement the application circuit which is VLC and CAN communication and explain the principle. Circuit's pulse features are demonstrated by each part's signal. Total communication distance is 3m and it's transmission performance is error free.

• Journal of Sensor Science and Technology
• /
• v.25 no.5
• /
• pp.303-309
• /
• 2016

In this paper, we introduce a new method for controlling the illumination of LEDs in visible light communication (VLC) by changing the duty cycle of Manchester code. When VLC data were transmitted in Manchester code, the average optical power of the LEDs was proportional to the duty cycle. In experiments, we controlled the illumination of a $3{\times}3$ LED array from 10% to 90% of its peak value by changing the duty cycle of the Manchester code. The synchronizing clocks required for encoding and decoding the Manchester code were supplied by pulse generators that were connected to a 220 V power line. All pulse generators made the same pulses with a repetition frequency of 120 Hz, and they were synchronized with the full-wave rectified voltage of the power line. This scheme is a very simple and useful method for constructing indoor wireless sensor networks using LED light.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.23 no.4
• /
• pp.419-428
• /
• 1986

While three most important aspects of line codes are the de-free, the minimum-bandwidth, and the self-clocking properties, the only TIBr, VMDBr, RMD3r, RMD4r codes possess all of these properties. This paper is to report the results of an experimental performance study of VMDB5. The encoder and decoder of VMDB5 and the pulse shaper have been inplemented. Power spectra, eye patterns, and error probabilities are experimentally measured, confirming the theoreticla performance predictions. It has been observed that the NRZ pulse shaping reliable transmission is possible with no extra equalization even in teh case when the -3dB channel bandwith is only half the Nyquist bandwidth.

• Journal of Electrical Engineering and Technology
• /
• v.3 no.3
• /
• pp.391-400
• /
• 2008

Multi-pulse topology of converters using elementary six-pulse GTO - VSC (gate turn off based voltage source converter) operated under fundamental frequency switching (FFS) control is widely adopted in high power rating static synchronous compensators (STATCOM). Practically, a 48-pulse ($6{\times}8$ pulse) configuration is used with the phase angle control algorithm employing proportional and integral (PI) control methodology. These kinds of controllers, for example the ${\pm}80MVAR$ compensator at Inuyama switching station, KEPCO, Japan, employs two stages of magnetics viz. intermediate transformers (as many as VSCs) and a main coupling transformer to minimize harmonics distortion in the line and to achieve a desired operational efficiency. The magnetic circuit needs altogether nine transformers of which eight are phase shifting transformers (PST) used in the intermediate stage, each rating equal to or more than one eighth of the compensator rating, and the other one is the main coupling transformer having a power rating equal to that of the compensator. In this paper, a two-level 48-pulse ${\pm}100MVAR$ STATCOM is proposed where eight, six-pulse GTO-VSC are employed and magnetics is simplified to single-stage using four transformers of which three are PSTs and the other is a normal transformer. Thus, it reduces the magnetics to half of the value needed in the commercially available compensator. By adopting the simple PI-controllers, the model is simulated in a MATLAB environment by SimPowerSystems toolbox for voltage regulation in the transmission system. The simulation results show that the THD levels in line voltage and current are well below the limiting values specified in the IEEE Std 519-1992 for harmonic control in electrical power systems. The controller performance is observed reasonably well during capacitive and inductive modes of operation.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.718-722
• /
• 2001

This paper proposes an SSSC based on multi-bridge inverters in PWM scheme. The proposed system consists of 6 H-bridge inverter modules per phase. The dynamic characteristic of proposed system was analyzed by simulation with EMTP codes, assuming that the SSSC is inserted in the 154-kV transmission line of one-machine-infinite-bus power system. The feasibility of hardware implementation was verified through experimental works with a scaled-model. The proposed system can be directly inserted in the transmission line without coupling transformers, and has flexibility in expanding the operation voltage by increasing the number of H-bridges.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.05a
• /
• pp.479-482
• /
• 2001

We have measured terahertz electromagnetic pulses when DC voltage from V up to 90V is applied to the transmitter chip excited by femto-second laser pulse. The femto-second excitation laser pulse was injected to transmitter chip. Finally, we are observed the amplitude of electromagnetic pulse and variation of spectrum. Consequently, the amplitude of spectrum was increased to high frequency according to increase of voltage. At that time, the signal-to-noise rate(SNR) is increased from 250:1 to 10, 000:1.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.16 no.1
• /
• pp.14-21
• /
• 1979

This paper deals with tIne interface error in the on-line computer systems by using the FSK radio communications. The wideband frequency shrift keying method is used for briary data transmission between the remote terminals and the main computer. To mintmize the error rate In the decoder systems of the main computer, a synchronizing pulse is added to the frame, so that the phase In both receiver and transmitter are synchronized. When the information signal with a constant error bit is received through FSK, It is designed to use the microprocessor for calculation of error bit. As results, most bit error are caused in FSK radio communications. and a few error bit Is me - asured to enter the mirroprocessor from the input buffer.

• Proceedings of the IEEK Conference
• /
• 2002.07a
• /
• pp.650-653
• /
• 2002

The increaseing speeds are accompanied by decreases in pulse rise and fall time in VLSI circuits. These accenturate the high frequency spectral contents of the signals and cause the frequency dependent loss of the conductors which interconnect the various sub-circuits composing of VLSI circuit. The lossy effect is approximated by the square root of frequency dependence of the per unit length resistance. In the practical applications, several problems may arise along with this approximation, so we extend our investigation of the lossy effect by numerical Laplace inversion method.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2005.11a
• /
• pp.197-202
• /
• 2005

In this paper, we analyzed the signal distortion incorporating meander-shaped transmission line on PCB in broadband frequency range, up to 50GHz. This broadband characteristic provides reasonable analysis of digital pulse having very short rising time. Simulation results reveal suppression characteristic at multiband which is dependent on only the width of meander arm. This width of arm also can be adjusted using different permittivity because it provides different effective wave-length. It is found that the suppression characteristic shows sharpness with as a function of the number of arms. However, these characteristics shown limitation for microstrip line structure rather than for stripline structure, so we can avoid these unwanted phenomena using stripline structure.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.12
• /
• pp.2113-2118
• /
• 2016

The precise detection of electric leakage point of underground power cable is very important to reduce cost and time of maintenance and prevent electric shock accident through expedite repair of electric leakage point. This paper proposes a electric leakage point detection system underground power cable using of half-period modulated transmission waveform and earth electric potential measurement. The developed system is composed of transmitter to generate the wanted pulse waveform, receiver to measure and display earth electric potential by the transmitted pulse in electric leakage point and PC Software program to display of GPS coordinate on detection cable line. The performance of the electric leakage point detection system was tested in the constructed underground cable leakage detection test bed. The test results on signal generation voltage precision of signal transmitter, mean detection earth voltage, mean detection leakage current and electric leakage point detection error showed the developed system can be used in electric leakage point detection underground power cable.