• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.2
• /
• pp.521-528
• /
• 2013

Urban drainage systems are generally designed as open channel flow. The system, however, shows a partially surcharged flow in its body, especially at junctions or manholes. Thus, a special case of this condition needs to be explained as pressurized flow condition for designing the sewer system. This study considered the surcharged manhole flows during an unexpected rainfall event or an excess of design frequency. Overflows from surcharged manholes and urban flooding can occur from the effect of surcharged flows. Thus, sewer systems should be designed with the concept of open channel flow and pressurized flow. Also, energy losses in a manhole need to be considered. The aim of this study is to develop the numerical model which can evaluate the effect of the energy losses at the manhole. The numerical model was verified and compared with hydraulic model and SWMM. The results showed that the water depth of numerical model was in good agreement with hydraulic model at the each manhole. However, the SWMM underestimated the water depth because that model ignored the energy losses at manholes. Thus, the developed numerical model in this study could be a useful tool for the assessment of a conveyance of urban drainage system.

• ETRI Journal
• /
• v.39 no.2
• /
• pp.234-244
• /
• 2017

Research interest in three-dimensional multiple-input multiple-output (3D-MIMO) beamforming has rapidly increased on account of its potential to support high data rates through an array of strategies, including sector or user-specific elevation beamforming and cell-splitting. To evaluate the full performance benefits of 3D and full-dimensional (FD) MIMO beamforming, the 3D character of the real MIMO channel must be modeled with consideration of both the azimuth and elevation domain. Most existing works on the 2D spatial channel model (2D-SCM) assume a wide range for the distribution of elevation angles of departure (eAoDs), which is not practical according to field measurements. In this paper, an optimal FD-MIMO planar array configuration is presented for different practical channel conditions by restricting the eAoDs to a finite range. Using a dynamic network level simulator that employs a complete 3D SCM, we analyze the relationship between the angular spread and sum throughput. In addition, we present an analysis on the optimal antenna configurations for the channels under consideration.

• Journal of Environmental Science International
• /
• v.18 no.1
• /
• pp.113-127
• /
• 2009

This study was designed to present a river model with an aim at restoring the ecosystem and improving the landscape along the urban rivers on the basin of the Namhan river, a core life channel for the National Capital region. The revelation of botanical status, transition trend and correlation of plants might lead to providing the urban river restoration projects and ecological river formation projects with basic data for a model of ideal aquatic ecology and landscape. The outcomes of this study could be summed up as follows: 1. Communities of Juglans mandshurica, Cornus controversa and Fraxinus mandshurica constitute the main portion of flora at or around uppermost branch streams of the River Namhanis harbored mainly in and around small brooks 2. Typical terrestrial forest communities formed around the River Namhan are composed mainly of Larix leptolepis, Pinus rigida, planned forestation of Pinus koraiensis, Quercus acutissima, Quercus variabilis and Pinus densiflora. 3. The analysis into terrestrial environment of plant communities showed a high content of $P_2O_5$, typical communities found in the artificially disturbed land Finally, it seems also desirable to continue to make every exertion to explore the relationship between fluvial and terrestrial ecologies with a purport of building up a model of natural streams in urban area based on the surveyed factors for plant life, forest communities, soil and landscape and, moreover, on the forecasting for overall influences derived from the relation upon the ecosystem.

• Journal of the Institute of Convergence Signal Processing
• /
• v.3 no.4
• /
• pp.67-73
• /
• 2002

There have been increased concerns on mobile stratospheric communication system(SCS) for the purpose of advanced service of personal and high speed communication systems. In fact, this SCS is considered and studied for IMT-2000 service by ITU. Although, it is important to make accurate channel model for prediction of the SCS performance, there is no measured channel data in this system. Thus, in this paper, we estimate the performance of SCS bye use of channel model provided by Corazza(2) and modified by You(3). And also, the effects of channel codings on system performance are analyzed by deriving bit error performance based on realistic Rician log-normal fading channel models. The performance results are divided into three kinds of areas with three kinds of elevation angles 20$^\cire$, 45$^\cire$, and 80$^\cire$. And also the effects of forward error correction channel codings on system performance with Hamming(7,4), HCH( IS,7) and convolutional code of constraint length 3 and code rate R=1/2.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.9
• /
• pp.1864-1869
• /
• 2012

We make an interference analysis to obtain a critical ctiteria for coexisting availability of WLAN and WiBro between adjacent channels can be used in TVWS(TV White Space). To meet this analysis, we set the various transmission parameters including the emission and blocking mask, antenna height and gain, transmission power and bandwidth, channel model etc. And, based on these parameters, we analyze on performances according to a variation of guard band, a number of service user and allowable transmit power of the user operating in the adjacent channels. In this paper, we consider a urban environment and apply a Extended Hata-SRD for WLAN and an interference link and Extended Hata model for WiBro, respectively. With these results, we can see how each system can be shared in an adjacent channel.

• Journal of Korea Water Resources Association
• /
• v.33 no.6
• /
• pp.701-709
• /
• 2000

Integrated storage function model (ISFM) is applied to some rainfall-runoff events of the selected basins in Korea to show validity of the proposed model. Comparing the numerical results of the model with the field measurements, the simulated hydrographs and peak flood discharges for the most part showed good agreements, except the occurrence time of the peak discharges which showed a bit discrepancy, and they showed it was very hard to have a sufficient lead-time to forecast the flood when the upstream inflow of the channel reach was more dominant than the inflow from the residual watershed of the channel.hannel.

• Journal of Korean Society on Water Environment
• /
• v.21 no.6
• /
• pp.682-686
• /
• 2005

Recently some urban areas have been flooded due to heavy storm rainfalls. Though major causes of these floodings may be attributed to localized heavy rainfalls, other factors are related to urban flooding including deficiency of storm sewer network capacity, change of surface runoff due to covered open channels, and operational problems of storm drainage pump stations. In this study, hydrologic and hydraulic analysis of Sutak basin in Guri city were carried out to evaluate flooding problems occurred during the heavy storm in July, 2001. ArcView, a world most widely used GIS tool, was used to extract required data for the hydrologic analysis including basin characteristics data, concentration times, channel routing data, land use data, soil distribution data and SCS runoff curve number generation from digital maps. HEC-HMS, a GIS-based runoff simulation model, was successfully used to simulate the flood inflow hydrograph to Sutak pumping station.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.18 no.4
• /
• pp.338-347
• /
• 2006

A small hydro-power plant using the seawater used as the cooling (circulated) water and discharged is under construction. The bigger size of the small hydro-power plant, the better in order to maximize the efficiency and the electric power. The optimal size, however, should be determined in the constraints of the channel un-disturbed range. The water level change should be checked in detail based on the hydraulic behaviour. In this study, the FLOW3D model, three-dimensional flow model, is setup using the flow measurement data in the effluent discharge channel and the flow pattern changes due to the small hydro-power plant construction are predicted by the model. The plant construction makes the increasing of the water level, and the water level in the upstream of the channel weir is increased 65 cm from 4.32 m to 4.97 m, in the condition of the design discharge $156m^3/s$ and the movable weir height of the hydro-power plant 3.8 m.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.521-531
• /
• 2018

This paper presents a procedure for field measurements which provides a generalized Narrowband Power Line Communications (NB-PLC) channel model for low voltage (LV) access network in order to deploy advanced metering infrastructure (AMI) within Lahore, Pakistan. The measurements of allocated sites were performed in the residential (urban and rural), industrial and commercial electricity consumers for the NB-PLC channel modeling of overhead transmission lines (TLs). On the basis of extensive field measurement results, the average attenuation profile and transfer functions are presented. The results obtained from field measurements are validated by comparing them with a proposed Simulink model. A close agreement in the measured and simulated transfer function (TF) results is observed. The proposed Simulink model is an effort to model the NB-PLC channels in an effective way, especially in South Asian countries.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2006.03a
• /
• pp.79-93
• /
• 2006

It is well known that acoustic emission (AE) is indicator of rock fracturing or damage as rock is brought to failure under the uniaxial compressive loads. In this paper, an experimental study on the source location of acoustic emission on the cylindrical specimens of granite under uniaxial compression test was made. The AE source location was made by measuring the six channel AE data. Comparing to this experiment, the numerical method is applied to model the initiation and propagation of fracture by AE using a numerical code, RFPA (Realistic Failure Process Analysis). This code incorporates the mesoscopic heterogeneity in Young's modulus and rock strength characteristic of rock masses. In the numerical models, values of Young's modulus and rock strength are realized according to a Weibull distribution in which the distribution parameters represent the level of heterogeneity of the medium. The results of the simulations show that RFPA can be used not only to produce acoustic emission similar to those measurements in our experiments, but also to predict fracturing patterns under uniaxial loading condition.