• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.33-39
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• 2008

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1140-1147
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• 2013

In this paper, The path loss model of Air Traffic Control(ATC) telecommunication radio channel has been studied at the Incheon International Airport(IIA) Cargo Terminal. We measured one frequency among VHF channel bands. The transmitting site was located at different locations with different heights. The transmitting site radiated the Continuous Wave(CW). The propagation measurement was taken using the moving vehicle equipped with receiver and antenna. The transmitting power, frequency and antenna height are the same as the current operating condition. The path loss exponent and intercept parameters were extracted by the basic path loss model and hata model. The path loss exponent at IIA Cargo terminal area were 3.67 and 3.39 respectively in first and second transmitting sites. The deviation of prediction error is 14.42 and 10.38. The new path loss equation at the IIA Cargo terminal area was also developed using the derived path loss parameters. The new path loss was compared with other models. This result will be helpful for the ATC site selection and service quality evaluation.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.4
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• pp.94-102
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• 1999

This paper is related with the compensation of communication channel characteristics using predistorter, and the considered characteristic is the additive noise, phase rotation and frequency selective fading which occurred in communication channel. Predistorter can minimize the effect of obstacle element which occured in channel at receiving side by transmitting the predistortion of signal after modulation, the coefficient of inverse electrical charateristic of communication channel is performed at transmitting side. For this purpose, the predistorter is designed by using Tricepstrum Equalization Algorithm which is adaptive equlizer algorithm, and the receiving side must transmit the probing signal to transmitting side. Using the probing signal, the transmitting side can obtain the inverse characteristic coefficient of communication channel, and this probing signal must be transmitted periodically. We assumed that the channel characteristic do not change during this one period. As a result of computer simulation, we confirmed that the performance of predistorter was fairly good as same as the adaptive equalizer, and this technique have a effectiveness that can be used in the forward channel of mobile communication in order to achieve high speed transmission.

• Progress in Superconductivity and Cryogenics
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• v.16 no.3
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• pp.21-25
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• 2014

As wireless power transfer (WPT) technology using strongly coupled electromagnetic resonators is a recently explored technique to realize the large power delivery and storage without any cable or wire, this technique is required for diffusion of electric vehicles (EVs) since it makes possible a convenient charging system. Typically, since the normal conducting coils are used as a transmitting coil in the CPT system, there is limited to deliver the large power promptly in the contactless EV charging system. From this reason, we proposed the combination CPT technology with HTS transmitting antenna, it is called as, superconducting contactless power transfer for EV (SUWPT4EV) system. As the HTS coil has an enough current density, it can deliver a mass amount of electric energy in spite of a small scale antenna. The SUCPT4EV system has been expected as a noble option to improve the transfer efficiency of large electric power. Such a system consists of two resonator coils; HTS transmitting antenna (Tx) coil and normal conducting receiver (Rx) coil. Especially, the impedance matching for each resonator is a sensitive and plays an important role to improve transfer efficiency as well as delivery distance. In this study, we examined the improvement of transmission efficiency and properties for HTS and copper antennas, respectively, within 45 cm distance. Thus, we obtained improved transfer efficiency with HTS antenna over 15% compared with copper antenna. In addition, we achieved effective impedance matching conditions between HTS antenna and copper receiver at radio frequency (RF) power of 370 kHz.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.2
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• pp.111-117
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• 2019

We investigated the variations in the magnetic-field distribution and power transmission efficiency, resulting from changes in the relative positions of the transmitting and receiving coils, for electromagnetic-induction-type wireless power transmission using an elliptical receive coil. Results of simulations using a high-frequency structure simulator were compared to actual measurement results. The simulations showed that the transmission efficiency could be maintained relatively stable even if the alignment between the transmitting and receiving coils was changed to some extent. When the centre of the receiving coil was perfectly aligned with the centre of the transmitting coil, the transmission efficiency was the maximum; however, the degree of decrease in the transmission efficiency was small even if the centre of the receiving coil moved by ± 10mm from the centre of the transmitting coil. Therefore, it is expected that the performance of the wireless power transmission system will not be degraded significantly even if perfect alignment is not maintained. The results suggested a standardized application method of wireless transmission in the utilization of wireless power for implantable sensors.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.2
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• pp.29-36
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• 2004

The purpose of this study is to analyze DMB(digital multimedia broadcasting) technologies of transmitting GIS-based traffic information for developing DMB systems compared with FM DARC(FM data radio channel). R&D and standardizations for transmitting GIS-based traffic information have been rapidly changed, as radical developments in ITS(intelligent transportation systems), telemaics, and communication methods such as ubiquitous and convergences of broadcasting and communications. Each communication method employs different GIS format, protocol, and standardizations, i.e., GML(geography markup language) and TPEG(transport protocol experts group). This paper presents technical methods and trends of transmitting traffic information using broadcasting along with FM DARC, in general, and DMB, in particular.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.5
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• pp.578-588
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• 1998

In this paper, we analyzed the propagation characteristics of polarization diversity in the view of diversity gain, cross correlation coefficient and average received signal strength, and compared it with those of space diversity. From the results, we could confirm that in the care of line of sight(LOS), space diversity gain is bigger than polarization diversity gain by 2 dB and the diversity gain of mobile transmitting with 90 degree is bigger than that of mobile transmitting with 45 degree by 1 dB. However, in the area of non-line of sight(NLOS), the diversity gains were all most the same in two diversity schemes and in specular cases, polarization diversity showed better performances. Also it was verified that under the NLOS conditions, diversity gain of mobile transmitting with 45 degree was at least 1 dB bigger than that of mobile transmitting with 90 degree.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.5
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• pp.9-16
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• 2004

The data link layer of the PCI Express must have the transmitting buffer that contains the packets to transmit next time. Also it must have the retry buffer that contains the packets which were already transmitted but have not been acknowledged by the corresponding target device. In the separated buffer architecture, the data link layer can not transmit the packets in the transmitting buffer if the reiry buffer space is not enough. In this paper, we propose an efficient buffer architecture which merges the transmitting buffer and the retry buffer to a single buffer. Since the proposed buffer can dynamically assign the size of the transmitting buffer and the retry buffer, it can improve the buffer usage efficiency and the data transfer efficiency. The simulation result shows that the proposed buffer has the higher data transfer efficiency than the separated buffer architecture about 39% when the total buffer size is 8K byte.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.48-55
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• 2021

The 3-coil magnetic resonance wireless power transmission system was analyzed using an equivalent circuit model, and the |S21| of the system was expressed as the equation of the Q of the three coils, the coupling coefficient k between the transmitting coil and the relay coil, the relay coil and the receiving coil. It is suggested that the maximum efficiency can be obtained when the relay coil is located in the center of the transmitting and the receiving coil. When the distance between the transmitting and the receiving coil is 30 cm and the two coils are aligned, maximum efficiency of 9 % is obtained with the relay coil centered between the coils. If the transmitting coil and the receiving coil are misaligned during a wireless charging of an electric vehicle, the efficiency is expected to decrease significantly compared to the aligned case. It is expected that the efficiency can be increased by using a relay coil and by rotating the coil.

• Economic and Environmental Geology
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• v.57 no.1
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• pp.17-23
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• 2024

Ground penetrating radar (GPR) survey is a geophysical method that utilizes electromagnetic waves reflecting from a boundary where the electromagnetic property changes. As the frequency of the antenna is about 25 MHz ~ 1 GHz, it is effective to acquire high resolution images of underground pipe, artificial structure, underground cavity, and underground structure. In this study, we analyzed the change of signals reflected from the same underground objects according to the arrangement of transceiver antennas used in ground penetrating radar survey. The antenna used in the experiment was 200 MHz, and the survey was performed in the vertical direction across the sewer and the parallel direction along the sewer to the sewer buried under the road, respectively. A total of five antenna array methods were applied to the survey. The most used arrangement is when the transmitting and receiving antennas are all perpendicular to the survey line (PR-BD). The PR-BD arrangement is effective when the object underground is a horizontal reflector with an angle of less than 30°, such as the sewer under investigation. In this case study, it was confirmed that the transmitter and receiver antennas perpendicular to the survey line (PR-BD) are the most effective way to show the underground structure. In addition, in the case where the transmitting and receiving antennas are orthogonal to each other (XPOL), no specific reflected wave was observed in both experiments measured across or parallel to the sewer. Therefore, in the case of detecting undiscovered objects in the underground, the PR-BD array method in which the transmitting and receiving antennas are aligned in the direction perpendicular to the survey line taken as a reference and the XPOL method in which the transmitting and receiving antennas are orthogonal to each other are all used, it can be effective to apply both of the above arrangements after setting the direction to 45° and 135°.