• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.174-177
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• 1999

The propagation loss of silica slab waveguides were measured by immersing slab waveguides into a index matching liqiud. Index matching liqiud was used for out-coupling the light from arbitrary points of slab waveguide. The measured value of propagation loss are 0.04 dB/cm and 0.09 dB at 1300 nm and 633 nm respectively.

• ETRI Journal
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• v.28 no.2
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• pp.247-249
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• 2006

In the development of a new wireless communications system, a versatile and accurate radio channel for indoor communications is needed. In particular, the investigation of radio transmission into buildings is very important. In this letter, we present an improved three-dimensional electromagnetic wave propagation prediction model for indoor wireless communications that takes into consideration building penetration loss. A ray tracing technique based on an image method is also employed in this study. Three-dimensional models can predict any complex indoor environment composed of arbitrarily shaped walls. A speed-up algorithm, which is a modified deterministic ray tube method, is also introduced for efficient prediction and computation.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.373-378
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• 1995

Bending losses of bent optical waveguides are calculated by virtue of the finite difference-beam p propagation method in the cylindrical coordinate system. In order to minimize the radiating losses of bent optical waveguides, we apply the trench structure to the bent waveguides and perform the a analysis to keep track of: 1) the influence of curvature radius on the bending loss without the trench, 2) the influence of curvature radius and refractive index difference on the bending loss with the trench, 3) the influence of the trench width on the bending loss.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.55-63
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• 2018

In this paper, we measured the propagation path loss by a ground to air flight communication test at UHF band and analyzed the results. The ground receiving terminal was located at 1,100m above sea level in Cheju Island and the airborne transmit terminal flew at an altitude of 3.5km from 150 to 220km from the ground terminal. In this case, the ground terminal and the airborne terminal are on the Line of Sight. Therefore loss in this communications environment can be predicted based on Free Space Loss. However, in this test, the sea level exists between two terminals, and due to the very small angle of incidence on the reflecting surface due to the long-range communication environment, it is not possible to accurately predict the loss of free space only. Therefore, considering that there are no surrounding obstacles and that a line of sight is secured between the end of two terminals, we applied a plane earth reflection model and a spherical earth reflection model to estimate the propagation path loss and compared with the actual test results. As a result of the comparison, the predicted propagation path loss by a spherical earth reflection model were quite similar to the actual test values.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.1-10
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• 2024

The radio propagation characteristics of the 6, 10, and 17 GHz frequency bands in multiple paths in an indoor lobby environment were analyzed. The line-of-sight (LOS) and non-LOS (NLOS) paths were measured from a distance of 2-16 m (0.5 m intervals) from the transmitting to the receiving antenna positions. For basic transmission losses, three parameters were compared using the floating intercept path loss model corresponding to the path. For a root mean square delay spread, the measurement results were compared for cumulative probabilities of 10, 50, and 90%. Propagation loss and propagation delay occurred in all measured frequencies owing to the existence of pillars and an unusual lobby structure. Thus, a measurement scenario for an indoor lobby environment and the provision of standard measurement data was proposed. The results may facilitate research on the radio propagation characteristics of 5G and millimeter-wave bands in indoor lobby environments with various structures.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.105-109
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• 2013

There are the free space model, the direct-path and ground reflected model, Egli model, Okumura-Hata model in the representative propagational models. The measured results at the area of PNG area were used as the experimental data in this paper. The new proposed partial interval analysis method is applied on the measured propagation data in the cellular band. The interval for the analysis is divided from the entire 30 Km distance to 5 Km, and next to 1 Km. The best-fit propagation models are chosen on all partial intervals. The means and standard deviations are calculated for the differences between the measured data and all partial interval models. By using the 5 Km- or 1 Km- partial interval analysis, the standard deviation between the measured data and the partial propagation models was improved more than 1.7 dB.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.337-338
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• 2008

In this paper, propagation analysis method in using Walfish-Ikegami propagation model in wireless cell planning is proposed. Through Walfish-Ikegami model, we can predict the distribution of propagation loss of the received signal. For correct and low complex analysis, quick LOS search method and path loss offset calibration using measured data are included in Walfish-Ikegami model. In CellTREK that is developed by KT, it is showed that the proposed model outperforms Modified HATA model when comparing with measured data in Wibro system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.9
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• pp.765-772
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• 2013

In this paper, we studied the path loss model of Air Traffic Control(ATC) telecommunication radio channel at the Incheon International Airport(IIA) concourse area. We measured wave propagation characteristics on the two frequencies among VHF/UHF channel bands. 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 exponents at Concourse area were 3.1/3.13 and 3.01/3.38 respectively in 128.2MHz and 269.1MHz. The deviation of prediction error is 2.77/3.17 and 4.01/3.66. The new path loss equation at the Concourse area was also developed using the derived path loss parameters. The new path loss model was compared with other models. This result will be helpful for the ATC site selection and service quality evaluation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.763-771
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• 2013

In this paper, the propagation characteristics for ISM(Industrial Scientific and Medical) and TVWS(TV White Space) in indoor building environment are analyzed in comparison with theoretical and experimental results, the excellent propagation characteristics of the TVWS is confirmed. To this end, signals which have center frequencies of 503 MHz and 2.4 GHz are generated in building propagation environment. Through that, received power strength is measured according to the location and measured path loss is analyzed. Theoretical path loss is calculated using Hata, Extended Hata, Extended Hata SRD, ITU-R P.1238 and reliability for channel model in indoor environment is analyzed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2047-2053
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• 2008

Auto-ID industries and their services have been improved since decades ago, and radio frequency identification (RFID) has been contributing in many applications. Product management can be the foremost example. In our industrial experiences, RFID in ultra high frequency (UHF) band provides much longer interrogation ranges than that of 13.56MHz; many more applications exist thereby. There should be several interesting and useful ideas on UHF RFID; however, those ideas can be limited due to the inevitable environmental circumstances that restrict the interrogation range in shorten value. This paper discusses the propagation interference among different types of readers (e.g, mobile RFID readers in stationary reader zone) in dense-reader environment. In most cases, UHF RFIDs in Korea will be dependent on the UHF mobile RFIDs. In this sense, the UHF mobile users accidently move into the stationary reader's interrogation zone. This is serious problem. In this paper, we analyze propagation loss and propose the effective channel allocation scheme that can contribute developing less-invasive UHF RFID networks. The simulation and practical measurement process using the commercial CAD tools and measurement equipments are presented.