• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1A
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• pp.1-7
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• 2011

Cell Capacity and cell layout are strongly dependent on the up-link interference caused by out-of-cell mobiles. Accurate prediction of the propagation path loss from out-of-cell mobiles is essential to achieve system designs that minimize the infrastructure required for a given quality of service (QOS). Less accurate predictions can be expected to yield designs requiring the use of a greater number of base stations. In order to quantify the dependence of infrastructure on prediction accuracy, this paper considers the cellular systems, LOS (line of sight) cells along a road or highway.

• Korean Journal of Environmental Agriculture
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• v.19 no.3
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• pp.252-258
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• 2000

SWMM and WASP5 were applied for pollutant loading estimate from watershed and reservoir water quality simulation, respectively, to predict estuarine reservoir water quality. Application of natural systems to improve estuarine reservoir water quality was reviewed, and its effect was predicted by WASP5. Study area was the Hwa-Ong reservoir in Hwasung-Gun, Kyonggi-Do. Procedures for estimation of pollutant loading from watershed and simulation of corresponding reservoir water quality were reviewed. In this study, SWMM was proved to be an appropriate watershed model to the nonurban area, and it could evaluate land use effects and many hydrological characteristics of catchment. WASP5 is a well known lake water quality model and its application to the estuarine reservoir was proved to be suitable. These models are both dynamic and the output of SWMM can be linked to the WASP5 with little effort, therefore, use of these models for reservoir water quality prediction in connection was appropriate. Further efforts to develop more logical and practical measures to predict reservoir water quality are necessary for proper management of estuarine reservoirs.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.110-113
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• 2016

In this paper of ka band satellite communication using geostationary satellite is very weak to rainfall. So the rain attenuation reflect the values calculated using the satellite communication links vulnerable when designing a more reliable rainfall area distribution of rain attenuation and accurate predictive models must analyze the link budget. In this paper, by utilizing domestic distribution analysis in the recent local rainfall Crane and regional rainfall in the model and compared with the country of the regional distribution of rainfall in your area to fit the rain attenuation in Ka band frequency characteristics Crane rain attenuation prediction models were analyzed to between geostationary satellites and ground station position, distance and year time percentage(%).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.51-56
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• 2014

TETRA(TErrestrial Trunked RAdio) provide specialized disaster radio communication services as a standard European for digital TRS(Trunked Radio System). Especially, DMO(Direct Mode Operation) feature is used effectively in the radio shadow areas which base station does not propagate radio signal because it can communicate directly with terminal to terminal without base station's relay function. However, to effectively used DMO feature, radio coverage prediction information should be provided to users. Therefore in this paper, we were calculated link budget of TETRA DMO terminals which were distributing and operating in the country and then predicted reaching distance about radio propagation to be applied with path loss model.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.633-634
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• 2006

The aim of present work is to link geometrical parameter of maximum area of structural defect $\sqrt{area}\;_{max}$ (proposed by Y. Murakami, 1983) with surface fatigue mechanisms. Determined relations allow making predictions of surface fatigue properties of cemented carbides (WC-Co hardmetal - H15 - 85wt% WC and 15wt %Co, TiC-based cermets - T60/8 - 60wt %TiC and Fe/8wt% Ni and T70/14 - 70wt %TiC and Fe/14wt% Ni) in conditions of rolling contact and impact cycling loading. Pores considered being equivalent to small defects. Three comparative defects conditions are distinguished: surface pore, just below free surface and interior pores. The Vickers hardness of binder (as main responsible for the fracture mechanism of hardmetal and cermets) assumed to be the basis of such assumption. The estimate of this prediction has been done by analyzing the pore sizes using the statistics of extremes. The lower bound of fatigue properties can be correctly predicted by considering the maximum occurring pore size.

• Advances in concrete construction
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• v.1 no.3
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• pp.201-213
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• 2013

While recognizing the problem of reinforcement corrosion and premature structural deterioration of reinforced concrete (RC) structures as a combined effect of mechanical and environmental actions (carbonation, ingress of chlorides), emphasis is given on the effect of the latter, as most severe and unpredictable action. In this study, a simulation tool, based on proven predictive models utilizing principles of chemical and material engineering, for the estimation of concrete service life is applied on an existing reinforced concrete bridge (${\O}$resund Link) located in a chloride environment. After a brief introduction to the structure of the models used, emphasis is given on the physicochemical processes in concrete leading to chloride induced corrosion of the embedded reinforcement. By taking under consideration the concrete, structural and environmental properties of the bridge investigated, an accurate prediction of its service life is taking place. It was observed that the proposed, and already used, relationship of service lifetime- cover is almost identical with a mean line between the lines derived from the minimum and maximum critical values considered for corrosion initiation. Thus, an excellent agreement with the project specifications is observed despite the different ways used to approach the problem. Furthermore, different scenarios of concrete cover failure, in the case when a coating is utilized, and extreme deicing salts attack are also investigated.

• Geomechanics and Engineering
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• v.34 no.1
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• pp.69-86
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• 2023

To overcome the dilemma of the [BQ] method's inability to predict mountain tunnel support loads, this study is based on the Hoek-Brown criterion and previous results to obtain the connection equations from GSI scores to each parameter of the Hoek-Brown criterion and the link between the [BQ] scores and the GSI system. The equations were embedded in the Hoek-Brown criterion of FLAC6.0 software to obtain tunnel construction forecasts without destroying the in-situ stratigraphy. The feasibility of the secondary development of the Hoek-Brown criterion was verified through comparative analysis with field engineering measurements. If GSI > 45 with a confining pressure of less than 10 MPa, GSI has little effect on the critical softening factor while we should pay attention to the parameter of confining pressure when GSI < 45. The design values for each parameter are closer to the FLAC3D simulation results and the secondary development of the Hoek-Brown criterion meets the design objectives. If the Class V surrounding rock is thinned with shotcrete or the secondary lining is installed earlier, the secondary lining may act as the main load-bearing structure. The study may provide ideas for rapid prediction of mountainous tunnels in China.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.813-821
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• 2000

The engineering of satellite communication systems at frequencies above 10GHz requires a method for estimating rain-caused outage probabilities on the earth-satellite path. A procedure for predicting a rain attenuation distribution from a point rainfall rate distribution is, therefore, needed. In order to predict rain attenuation on the satellite link, several prediction models such as ITU-R, Global, SAM, DAH model, have been developed and used at a particular propagation condition, they may not be appropriate to a propagation condition in Korean territory. In this paper, a new rain attenuation prediction method appropriate to a propagation condition in Korea is introduced. Based on the results from ETRI measurements, a new method has been derived for an empirical approach with an identification on the horizontal correction factor as in current ITU-R method, and the vertical correction factor has been suggested with decreasing power law as a function of rainfall rate. This proposed model uses the entire rainfall rate distribution as input to the model, while the ITU-R and DAH model approaches only use a single 0.01% annual rainfall rate and assume that the attenuation at other probability levels can be determined from that single point distribution. This new model was compared with several world-wide prediction models. Based on the analysis, we can easily know the importance of the model choice to predict rain attenuation for a particular location in the radio communication system design.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.589-595
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• 2007

Korea Railroad Research Institute has developed the driverless rubber-tired K-AGT (Korean-Automated Guideway Transit) system from 1999 to 2005 and has done its performance and reliability tests on the test line at Gyeongsan-city. Radio Frequency Communication-Based Train Control system of K-AGT, which employed Advanced Automated Train Control scheme, detects train position using the radio propagation delay between wayside and vehicle radio equipment. In this paper, we investigate whether the transmission power of radio system can be reduced to the permitted level announced by the Ministry of Information and Communication for license-free ISM(Industrial Scientific Medical) frequency bands. We first determine radio propagation model, using the measured data at test line, and perform simulation for radio coverage prediction. From the simulation results, we identify that the radio system operated with reduced power can provide good link quality in total test line.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.1-15
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• 2023

In this study, the number of truck traffic accidents was predicted by using Poisson and negative binomial regression analysis to understand what factors affect accidents using expressway data. Significant variables in the truck traffic accident prediction model were continuous driving time, link length, truck traffic volume. number of bridges and number of drowsy shelters. The calculated LOSS rating was expressed on the national expressway network to diagnose the risk of truck accidents. This is expected to be used as basic data for policy establishment to reduce truck accidents on expressways.