• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.1
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• pp.28-37
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• 2010

In this paper, the IC (Integrated Circuit) for multi-channel asynchronous communication was designed by using FPGA and VHDL language. The existing chips for asynchronous communication that has been used commercially are composed of one to two channels. Therefore, when communication system with two channels or more is made, the cost becomes high and it becomes complicated for communication system to be realized and also has very little buffer, load that is placed into Microprocessor increases heavily in case of high speed communication or transmission of high-capacity data. The designed IC was improved the function and performance of communication system and reduced costs by designing 8 asynchronous communication channels with only one IC, and it has the size of transmitter/receiver buffer with 256 bytes respectively and consequently high speed communication became possible. To detect errors between communications, it was designed with digital filter and check-sum logic and channel MUX logic so that the malfunction can be prevented and errors can be detected more easily and input/output port regarding each communication channel can be used flexibly and consequently the reliability of system was improved. It was composed and simulated logic of VHDL described by using Cyclone II Series EP2C35F672C8 and QuartusII V8.1 of ALTERA company. In order to show the performance of designed IC, the test was conducted successfully in QuartusII simulation and experiment and the excellency was compared with TL16C550A of TI (Texas Instrument) company and ATmegal28 general-purpose micro controller of ATMEL company that are used widely as chips for asynchronous communication.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.3
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• pp.28-34
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• 2010

In this paper, the transceiver for RFID reader using 13.56MHz as a carrier frequency and meeting International Standard ISO 14443 type A, 14443 type B and 15693 is presented. The receiver is composed of envelope detector, VGA(Variable Gain Amplifier), filter, comparator to recovery the received signal. The proposed automatic reference voltage generator, positive peak detector, negative peak detector, and data slicer circuit can adjust the decision level of reference voltage over the received signal amplitudes. The transmitter is designed to drive high voltage and current to meet the 15693 specification. By using inductor loading circuit which can swing more than power supply and drive large current even under low impedance condition, it can control modulation rate from 30 percent to 5 percent, 100 perccnt and drive the output currents from 5 mA to 240 mA depending on standards. The 13.56 MHZ RFID reader is implemented in $0.18\;{\mu}m$ CM08 technology at 3.3V single supply. The chip area excluding pads is $1.5mm\;{\times}\;1.5mm$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.4
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• pp.6-14
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• 2011

The fast growing of the number of users requires the development of reliable communication systems able to provide higher data rates. In order to meet those requirements, techniques such as Multiple Input Multiple Out (MIMO) and Orthogonal Frequency Division multiplexing (OFDM) have been developed in the recent years. In order to combine the benefits of both techniques, the research activity is currently focused on MIMO-OFDM systems. In addition, for a fast wireless channel environment, the data rate and reliability can be optimized by setting the modulation and coding adaptively according to the channel conditions; and using sub-carrier frequency, and power allocation techniques. Depending on how accurate the feedback-based system obtain the channel state information (CSI) and feed it back to the transmitter without delay, the overall system performance would be poor or optimal. In this paper, we propose a Signal to Noise Ratio (SNR) estimation algorithm where the preamble is known for both sides of the transciever. Through simulations made over several channel environments, we prove that our proposed SNR estimation algorithm is more accurate compared with the traditional SNR estimation. Also, We applied AMC on several channel environments using the parameters of IEEE 802.11n, and compared the Throughput performance when using each of the different SNR Estimation Algorithms. The results obtained in the simulation confirm that the proposed algorithm produces the highest Throughput performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.7
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• pp.747-756
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• 2014

In this paper, we propose a path loss model with the multiple antennas using diversity effect. Currently wireless communication systems use the multiple antennas in order to improve the channel capacity or diversity gain. However, until recently, many researches on path loss model only consider geographical environment between the transmitter and the receiver. There is no study about path loss model considering diversity effect. Nowaday wireless communication use the multiple antennas and we in common find examples using diversity scheme that is method in order to enhance a channel capacity. Moreover we anticipate that it work harder in future researches. But in this communication system, path loss model isn't established that predict strength of received signal. So, in order to predict strength of received signal, we take changing SNR by diversity gain. When exceeding the number of antennas of receiver are 7 in proposed model, diversity effect is saturated. Therefore we consider the number of antenna of receiver until 10. We find RMSE between proposed model and value of calculation is 1. We calculate the diversity gain by conventional BER curve. Proposed model can predict loss of received signal in system using multiple antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.758-765
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• 2018

This paper presents a 24-GHz frequency-modulated continuous wave(FMCW) radar transceiver with two Rx and one Tx channels in 65-nm complementary metal-oxide-semiconductor(CMOS) process and implemented it on a radar system using the developed transceiver chip. The transceiver chip includes a $14{\times}$ frequency multiplier, low-noise amplifier, down-conversion mixer, and power amplifier(PA). The transmitter achieves >10 dBm output power from 23.8 to 24.36 GHz and the phase noise is -97.3 GHz/Hz at a 1-MHz offset. The receiver achieves 25.2 dB conversion gain and output $P_{1dB}$ of -31.7 dBm. The transceiver consumes 295 mW of power and occupies an area of $1.63{\times}1.6mm^2$. The radar system is fabricated on a low-loss Duroid printed circuit board(PCB) stacked on the low-cost FR4 PCBs. The chip and antenna are placed on the Duroid PCB with interconnects and bias, gain blocks and FMCW signal-generating circuitry are mounted on the FR4 PCB. The transmit antenna is a $4{\times}4$ patch array with 14.76 dBi gain and receiving antennas are two $4{\times}2$ patch antennas with a gain of 11.77 dBi. The operation of the radar is evaluated and confirmed by detecting the range and azimuthal angle of the corner reflectors.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.6
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• pp.612-618
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• 2019

In the unmanned vehicle industry, the market is exploding due to the rapid development of public and private demands along with the technological development of the 4th Industrial Revolution. In addition, unmanned mobiles are being used for communication services. In this paper, we analyzed the communication performance of unmanned aerial vehicle according to the characteristics of Doppler frequency. The Doppler frequency was calculated using the geometric model of the unmanned aerial vehicle, and the Doppler frequency of 10km, 30km, 300km, 1000km per hour and the BER performance by AWGN were measured by considering the unmanned high speed unmanned vehicle based on the position of the controller. The Doppler frequency model uses a Dent model and adds additive white Gaussian noise (AWGN) to check the bit errors of the transmitter and receiver. Low speed unmanned vehicles generally exhibited a BER performance of 0.2, while high speed unmanned vehicles generally exhibited a BER performance of 0.06. As the frequency band increases at the same speed, the BER performance increases, and when the speed increases in the same frequency band, the BER performance decreases. This is confirmed by the simulation results to predict theoretically predictable BER performance. In the frequency bands of 2.6 GHz, 5 GHz, and 28 GHz, the BER characteristics by Doppler frequency and the BER characteristics by controller function are verified. effect was confirmed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.623-628
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• 2013

The retrodirective array antenna system is operated faster than existing techniques of beamforming due to its less complexity. Therefore, it is effective for beam tracking in the environment of fast vehicle. On the other hand, it also has difficulty in estimating AOA according to multipath environment or multiuser signals. To improve the certainty of estimating AOA), this article proposes hybrid digital retrodirective array antenna systme combined with MUSIC algorithm. In this paper, the digital retrodirective array antenna system is designed according to the number of antenna array by using only one digital PLL which finds angle of delayed phase. And we evaluate the performance of the digital retrodirective array antenna for the high speed tracking application. Performance is studied by simulink when the speed of mobile is 300km/h and the distance between transmitter and receiver is 100m and then we have to confirm the performance of the system in multi path environment. As a result, the mean of AOA (Angle Of Arrival) error is $4.2^{\circ}$ when SNR is 10dB and it is $1.3^{\circ}$ when SNR is 20dB. Consequently, the digital RDA shows very good performance for high speed tracking due to the simple calculation and realization.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.2
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• pp.104-111
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• 2008

The ECG is biomedical electrical signal occurring on the surface of the body due to the contraction and relaxation of the heart. This signal represents an extremely important measure for health monitoring, as it provides vital information about a patient's cardiac condition and general health. ECG signals are contaminated with high frequency noise such as power line interference, muscle artifact and low frequency nose such as motion artifact. But it is difficult to filter nose from ECG signal, and errors resulting from filtering can distort a ECG signal. The present study implemented a small-size and low-power ECG measurement system that can remove motion artifact for convenient health monitoring during daily life. The implemented ECG monitoring system consists of ECG amplifier, a low power microprocessor, bluetooth module and monitoring program. Amplifier was designed and implemented using low power instrumentation amplifier, and microprocessor was interfaced to the ECG amplifier to collect the data, process, store and feed to a transmitter. And bluetooth module used to wirelessly transmit and receive the vital sign data from the microprocessor to an PC at the receiving site. In order to evaluate the performance of the implemented system, we assessed motion artifact rejection performance in each situation with artificially set condition using adaptive filter.

• Applied Microscopy
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• v.36 no.3
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• pp.183-194
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• 2006

The threadlike structures of fascia were examined by tight and electron microscopy. In order to distinguish its tissue organization, we used staining methods including hematoxylin-eosin, Masson's trichrome, Van Gieson's collagen fiber stain and Kluver-Barrera's luxol fast blue for nerve stain. Under the light microscope, the threadlike structures were composed of many collagen fibers and nerve. In higher magnification, they looked like as the bundle of tubular structures. Many myoid cell-spindle nuclei were observed in the tissue, which were taken from the fascia. It was identical with Bonghan duct known as one of meridian network theory. In the early 1960's the North Korean Bong-Han Kim showed the anatomical structures of the acupuncture points, and explained the meridian system as the concrete duct network system. According to Bonghan theory the Bonghan ducts spread throughout the body Because it is believed that the duct could have the role of signal pathway, the theory was reinvestigated in these days. All of the threadlike structures isolated from fascia shows the abundance of collagen fibers. The electron microscope examination (TEM) could confirm the well arranged collagen fiber and nerve. This investigation reveals that superficial Bohghan duct are nerve fiber parallel running with collagen fibers. We conjectured that the intermingled structure of collagen fiber, blood vessel and nerve fiber might have the role of meridian system. And the more, regardless of histological research, the study on collagen fiber as response transmitter in acupuncture treatment are in need.

• Applied Microscopy
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• v.36 no.3
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• pp.227-234
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• 2006

To investigate the comparative effect of spherical and aspherical RGP lens were worn during 3 weeks on rabbit's cornea. Four white rabbits were worn right eyes with spherical lens and 4 white rabbits were worn right eyes with aspherical RGP lens. Left eyes were served as control. The rabbits were sacrificed at 3 weeks after fitting and observed morphological changes by scanning electron microscopy and also investigate proliferation rate of the corneal epithelium with RGP wearing. After spherical RGP lens wearing, the epithet layer damaged compared to aspherical lens. The superficial cell layer strip off seriously, cell size significantly changed abnormal. Both spherical and aspherical RGP lens fitting group showed so many bacteria and back surface of lens was found like a fern shape. The aspherical RGP lens original material type was some formal than spherical lens. We thought that these pattern was significantly altered with spherical lens by prohibited transmitter oxygen from atmosphere therefore the epithelium shape was changed. This suggested wearing the aspherical lens might be less physiologic than shperical lens fitting.