• Proceedings of the KSRS Conference
• /
• v.2
• /
• pp.784-787
• /
• 2006

Dual-polarized transmission is one of the effective methods to transmit such a high speed data thanks to two independent channel leads to the orthogonal feature between RHCP (Right-Hand Circular Polarization) and LHCP (Left-Hand Circular Polarization). However, in practical case, the transmitted signal by RHCP polarized antenna in satellite can be occurred at the output port of LHCP polarized antenna in ground station, vice versa. XPD (Cross-Polarization Discrimination) is the ratio of the signal level at the output of a receiving antenna that is nominally co-polarized to the transmitting antenna to the output of a receiving antenna of the same gain but nominally orthogonally polarized to the transmitting antenna. In this paper, the detailed estimation of XPD within the interface between satellite and ground station is written and the influence of XPD to link performance is also described.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.7
• /
• pp.9-16
• /
• 1998

The nput impedance of a patch-tupe dipole antenna for GPR is calculated by using the moment methods in case that the surrounding medium is modeled on a multi-layer structure consisting of lossy dielectircs. When the cone-type function equivalent to pulse basis function in employed, one of the double integration can be performed analytically. The remaining integration is excuted numerically in a finite rnage and analytically in asymptotic region. The current distributions and input impedances of those antennas are calculated numerically.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.10
• /
• pp.492-499
• /
• 2002

This paper presents the method for an estimation of discharge current waveform in short gap discharge by radiated electromagnetic fields. The method of current waveform estimation is to use the one antenna method (single field method) with a measured electric or magnetic field at given field point by a time domain antenna. In order to verify the availability of the estimation theory, the discharge current waveform estimation was performed by one antenna methods using the measured electric fields of Wilson & Ma and compared with experiments. In addition diagnosis technique for power equipments is able to prevent from large accidents by finding signs of tile accidents before they happen. From the results of the estimation of discharge current, we have a possibility for the application of insulation diagnosis technique for power equipments using S$F_6$ gas. From this point of view, this paper simulated discharge progress and partial discharge by using needle-plan electrodes system in S$F_6$, studied the distribution of frequency spectrum of the radiated electromagnetic waves using a biconical antenna and a spectrum analyzer. From the experimental results of this study, according to the consideration of the mutual relation between frequency spectrum of the radiated electromagnetic waves and discharge progress, it was confirmed that detecting Partial discharge and estimating discharge progress in S$F_6$ could be Possible.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.68 no.1
• /
• pp.83-89
• /
• 2019

In this paper, beam forming using moving least squares method (MLSM) is studied. In the previous research, the least squares method (LSM), one of the data interpolation methods, was used to determine the desired beam pattern and obtain a beam pattern that minimizes the square of the error with the desired beam pattern. However, LSM has a disadvantage in that the beam pattern can not be formed to satisfy the exact steering angle of the desired beam pattern and the peak sidelobe level (PSLL) condition. To overcome this drawback, MLSM is used for beam forming. In order to verify, the proposed method is applied in beam forming of Bezier platform array antenna which is one of conformal array antenna platform.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.37 no.10
• /
• pp.37-42
• /
• 2000

There has been a constant effort to study methods for increasing the bandwidth of antenna by microstrip patch. In this paper, we propose a special type of the external rectangular patch, for design and analysis of an antenna using a local multi-point distribution system (LMDS). We minimized electromagnetic emissions from the fringing effect. As a result, we obtained an increase in antenna efficiency and frequency bandwidth. We were also able to design the wide band antenna easily, because of the difference in parameter between the aimed and the simulated antenna was reduced greatly. In comparison with the rectangular patch antenna, the banded one has a wider bandwidth.

• International Journal of Computer Science & Network Security
• /
• v.24 no.7
• /
• pp.63-72
• /
• 2024

This is an extended paper, focusing on the cost management for the organizations dealing with the crucial issues of security systems. Information Technology (IT) is an important and irreplaceable need of society and all working sector's success depends on IT to a greater extent; therefore maintaining security features is one of the most important aspects of IT. When security in the IT sector is discussed, Patch Management (P.Mgnt) has to be taken under account. P. Mgnt includes many concerns and areas to be described for IT security such as methods and problems in updating patch, methods of reducing security risks with P.Mgnt, methods of achieving economies of scale by controlling the operational costs and taking decisions in investing as and when necessary. This paper presents a general definition of Patch management, its benefits and management of working cost through theoretical models, also the paper gives methods of feeding techniques for microstrip patch antenna MPA, showing the contracting and non contracting methods.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.11C
• /
• pp.1092-1099
• /
• 2006

Future wireless communication systems will employ spatial multiplexing with multiple antennas at both transmitter and receiver to take advantage of larger capacity gains as compared to the systems that use a single antenna. However, in order to reduce higher hardware costs and computational burden, it will require an efficient transmit-receive antenna selection algorithm, which we propose in this paper. Through simulation and comparative analysis of various existing methods and the one we propose in this paper, the algorithm we propose was validated as nearer to the optimal selection technique than existing nearly optimal antenna selection schemes.

• Journal of Positioning, Navigation, and Timing
• /
• v.12 no.1
• /
• pp.83-89
• /
• 2023

The Korea Augmentation Satellite System (KASS) system is a Satellite Based Augmentation System (SBAS) under development to provide APV-I SBAS service in the Republic of Korea. The KASS ground segment generates correction and integrity information for GPS measurements of KASS users using the accurate positions of KASS Reference Station (KRS) antenna phase centers. For this reason, the accuracy of KRS reference points through geodetic survey campaigns is one of the important factors for providing the KASS service in compliance with the required navigation performance. In order to obtain accurate positions, two geodetic survey campaigns were performed at several reference points, such as Mark, Center of Mast at Ground Level (CMGL), and Center of Hole in Top Plate (CHTP), of each KRS site using three different survey methods, the Virtual Reference Station (VRS), Flächen Korrektur Parameter (FKP), and raw data post-processing methods. By comparing and analyzing the results, the computed coordinates of the reference points were verified and Antenna Phase Center (APC) positions were calculated using KRS Antenna Reference Point (ARP) data, and the first KASS Site Acceptance Test (SAT#1) was performed successfully using the verified APC coordinates. After the first site survey activities, the KASS operators should maintain the coordinates with the required performance such that the overall KASS navigation performance commitment is guaranteed during the lifetime of 15 years. Therefore, the maintenance plan for the KRS antenna coordinates should be developed before the commissioning of KASS operation planned after 2023. Therefore, this paper presents a geodetic survey method selected for the maintenance activities and provides the rationale for using this method.

• International Journal of Aeronautical and Space Sciences
• /
• v.13 no.2
• /
• pp.250-259
• /
• 2012

The need for position information in indoor environments has been growing lately. Several indoor navigation systems have been studied. Among them, pseudolite-based indoor positioning systems are one of the best systems to obtain precise position measurements. However, the installation of such systems is very difficult because the calibration of pseudolite antenna position is complicated. For precise calibration, the use of carrier phase measurements is necessary, and whenever carrier phase measurements are considered, problems with cycle ambiguity appear. In this paper, a new approach to calibrate the positions of pseudolite antennas is proposed. By using a multi-antenna, the ambiguity can be eliminated, epoch by epoch, for every single carrier phase measurement. Moreover, the number of calibration points can be reduced down to 3 by use of measurements collected at unknown positions. Using the proposed methods, the process of the collection of carrier phase measurements becomes considerably simple and convenient. Simulation results are presented to verify the proposed algorithms.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.2
• /
• pp.259-267
• /
• 2000

This paper presents the method for an estimation of discharge current waveshapes in short gap discharge by radiated electromagnetic fields. The method of current waveform estimation described is using the one antenna method(single field method) and two antennal method(complex field method) with a measured electric or magnetic fields at given field point by a time domain antenna. In order to verify the availability of the estimation theory, the discharge current waveshape estimation was performed by one and two antenna methods using the measured electric fields of Wilson & Ma and compared with experiments.