• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.4
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• pp.407-416
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• 2020

Recent complex battle field demands Network Centric Warfare(NCW) ability to control various parts into a cohesive unit. In path planning filed, the NCW ability increases complexity of path planning algorithm, and it has to consider a communication coverage map as well as traditional parameters such as minimum radar exposure and survivability. In this paper, pros and cons of various propagation models are summarized, and we suggest a coverage map generation method using a Longley-Rice propagation model. Previous coverage map based on line of sight has significant discontinuities that limits selection of path planning algorithms such as Dijkstra and fast marching only. If there is method to remove discontinuities in the coverage map, optimization based path planning algorithms such as trajectory optimization and Particle Swarm Optimization(PSO) can also be used. In this paper, the Longley-Rice propagation model is used to calculate continuous RF strengths, and convert the strength data using smoothed leaky BER for the coverage map. In addition, we also suggest other types of rough coverage map generation using a lookup table method with simple inputs such as terrain type and antenna heights only. The implemented communication coverage map can be used various path planning algorithms, especially in the optimization based algorithms.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.1
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• pp.47-53
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• 2004

For the purpose of comparison between the designed coverage and actual coverage of Korean DGPS (Differential Global Position System) beacon stations, we have received the ship‘s positions with states and IDs of their stations on the navigation route of Jeju-Tianjin by automatic selection mode of DGPS receiver and on them of Jeju-Inchun and Jeju-Vladibostok by manual mode. Also in case that some obstructions were on propagation routes from DGPS beacon stations to receiving positions, a restriction on available ranges of DGPS beacon signals was investigated. The results obtained are as follows : 1. The coverage of Korean DGPS beacon stations was designed 100NM (Nautical mails) at 40.0dB(over ${\mu}$V/m). But the actual coverages of them according to their stations and propagation routes were 0.3-3.6 times as wide as designed coverage. 2. In case that the propagation route of beacon signals from DGPS beacon stations was on the sea, the propagation distance of north direction from the stations was longer than south direction. 3. The coverages of Echongdo and Ulungdo stations were 366NM on the yellow sea and 342.3NM on the east sea of Korea respectively, and were widest than any other stations. 4. The coverage of Marado station on the south and yellow seas of Korea was very unstable because of the Halla mountain on the propagation route. Maximum receiving range to be measured by automatic selection mode of DGPS receiver was 145NM on the route of Jeju-Tianjin on June 22-July 1, 2002. Minimum receiving range to be not measured by manual selection mode was 28.7NM on the route of Jeju-Inchun on June 26-28, 2003

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.587-596
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• 2008

For Wireless internet service in Metropolitan area, optimum location selection for base station and cell planning are critical process in determining service coverage by accurate prediction of Wave Propagation Characteristics. Due to different kinds of characteristics in service area such as lay of land, natural feature and material, height and width of artificially made building, it has a great impact on the transmission and distance recovery of wireless network service. Therefore, these facts may cause substantial barriers in predicting & analyzing the expected level of service quality and providing it to subscribers. In this thesis, we have simulated the process to improve quality and coverage of the service by adjusting the location of Base station and the antenna angle that influence the service after the basic location of base station is selected according to the wave prediction model. Based on this simulations test, we have demonstrated the results in which subscribers would get higher quality of wireless internet service along with bigger coverage and the improved quality in the same service coverage area through optimization process of base station.

• Journal of Broadcast Engineering
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• v.18 no.1
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• pp.59-65
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• 2013

Recently, the digital television transition from analog television to digital television has been progressing in terrestrial broadcasting. As a result of the DTV transition, additional reassignments and deployments of TV White spaces (TVWS) caused by co-channel interference (CCI) were needed. In this paper, we investigate the TVWS caused by CCI using Longley-Rice and ITU-R P.1546 propagation model, which are the most widely-used propagation model. In addition, we analyze the service coverage radius and CCI radius according to the height of transmitter antenna and transmitting power. The results show that the ratios of CCI radius to service coverage radius in Longley-Rice and ITU-R P.1546 propagation model are about 2.54 and 2.07, respectively.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.165-168
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• 1998

This paper describes the characteristics of CT-2 radio wave propagation at 900MHz range. Typical cell coverage of CT-2 based on picocellular design provides a 200m radius. The five sites of urban regions of Kwang Ju city were chosen to characterize propagation in various environments. On the basis of cell coverage data measured with field strength meter, average 75% of telepoint service was retained and it was lack 25% of overall gain. In some sites telepoint service was limited to two of four directions around a station. If specially designed collinear antenna with specific directivities are used in these shadow area, improved results will be acquired.

• The Transactions of the Korea Information Processing Society
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• v.6 no.5
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• pp.1342-1350
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• 1999

A new design procedure for micro cellular coverage prediction is presented here on this paper, which contains a new propagation analysis algorithm based on processing of vector data representing roads and buildings which mainly affect the propagation phenomena in micro-cell environments. The propagation analysis algorithm presented here has been developed to aim at the practical application for micro-cellular systems such as PCS or CE-2. As all the vectors used here are of closed poly lines, i.e., polygons, a simplified ray path search technique can be developed not only to determine if the calculation points are on the road polygons and but also to calculate the amount of blockage by buildings. The result shows a capability of predicting path loss with an RMS error of 5dB or lower.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.4
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• pp.266-276
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• 2001

Due to the rapid development of semiconductor technology, the complexity of VLSI circuits has heavily increased. With the increased densities of integrated circuits, several different types of faults can occur Thus, testing such circuits is becoming a sever problem. Delay testing can detect system timing failures caused by delay faults. However, the conventional delay fault coverage in terms of the number of detected faults may not be an effective measure of delay testing because, unlike a stuck-at-faults, the impact of a delay fault is dependent on its delay defect size rather than on its existence. Thus, the effectiveness of delay testing is dependent on the propagation delay of the path to be tested, the delay defect size, and the system clock interval. This paper proposes a new delay defect fault coverage that considers both propagation delay of the path to be tested and additional delay defect size. And the relationship between delay defect fault coverage and defect level is analyzed.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.209-214
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• 2007

In Korean geology that crystalline rock is dominant, the properties of subsurface including the anisotropy are distributed complexly and changed abruptly. Because of such geological environments, cross-hole seismic traveltime tomography is widely used to obtain the high resolution image of the subsurface for the engineering purposes in the geotechnical sites. However, because the cross-hole tomography has a wide propagation angle coverage relatively, its data tend to include the seismic velocity anisotropy comparing with the surface seismic methods. It can cause the misinterpretation that the cross-hole seismic data including the anisotropic effects are analyzed and treated with the general processing techniques assuming the isotropy. Therefore, we need to consider the seismic anisotropy in cross-hole seismic traveltime tomography. The seismic anisotropic tomography algorithm, which is developed for evaluation of the velocity anisotropy, includes several inversion schemes in order to make the inversion process stable and robust. First of all, the set of the inversion parameters is limited to one slowness, two ratios of slowness and one direction of the anisotropy symmetric axis. The ranges of the inversion parameters are localized by the pseudo-beta transform to obtain the reasonable inversion results and the inversion constraints are controlled efficiently by ACB(Active Constraint Balancing) method. Especially, the inversion using the Fresnel volume is applied to the anisotropic tomography and it can make the anisotropic tomography more stable than ray tomography as it widens the propagation angle coverage.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.125-128
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• 2000

In this paper, the handoff margins are analyzed using the propagation attenuation which is modeled as a product of the fourth power of the distant and a log-normal random variable whose standard deviation is 8 ㏈. The effect of handoff techniques on cell coverage for CDMA system are shown that soft handoff increases cell coverage relative to hard handoff. When the cell radius extends 5-10 % and the outage probability is 10 %, the relative cell coverage area is extended 3.22 ㏈-3.99 ㏈ and 2.55 ㏈-2.85 ㏈ with power control and without power control, respectively.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.2
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• pp.170-179
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• 2007

This paper introduces the optimal disposition of direction finder using EM(Electro-magnetic) wave propagation analysis which is based on LR(Longley-Rice) propagation model and the characteristics of direction finder, emitter and terrain. Initial model is simulated and modified to minimize propagation error as a result of the field trials. Proposed analysis used line-of-sight analysis and mountain-top extraction algorithm to optimize the disposition in the assigned area and the result can be displayed in the 3D map in order of the percentage coverage for direction finding possibility area.