• Journal of Korean Society of Transportation
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• v.19 no.2
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• pp.89-98
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• 2001

The objective of this Paper is to derive an adjustment factor for the presence of heavy vehicles when estimating capacity at unsignalized intersections (and/or at modern roundabouts). According to the 1997 and 2000 Highway Capacity Manual (HCM), potential capacity in such cases is estimated by simply adjusting base critical gap and base follow-up time. However, the procedure suggested in the HCM may lead to some errors in the adjustment, hence resulting in poor evaluation and design for the intersections, because it determines the value of adjusting factors by only the number of lanes on main streets regardless of the types of heavy vehicles. This paper shows a simple formula for making the adjustment. This formula is much like the HCM formula used for heavy vehicles in estimating highway capacity by the adoption of passenger car units (PCU). In contrast to the traditional approaches seen in the HCM, the PCU value of this case is explicitly expressed by the flow rate in the major streams and the gap difference in critical gaps chosen by passenger cars and particular heavy vehicles. Computational results of the adjustment factor are graphically illustrated.

• Journal of Communications and Networks
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• v.6 no.2
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• pp.106-111
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• 2004

The uplink capacity and the interference statistics of the sectors of the cigar-shaped W-CDMA microcells are studied. A model of 9 base station, assumed to be in a long tunnel, is used for the uplink analysis. The capacity and the interference statistics of the microcells are studied for different sector ranges, different propagation exponents, different antenna sidelobe levels, and different bend losses.

• Journal of the Korean Geotechnical Society
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• v.27 no.6
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• pp.39-48
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• 2011

In this paper the method of estimating the bearing capacity of shallow foundation on a finite layer of sandy ground underlain by a rigid base was proposed by assessing results of the model test and the numerical analyses. For model experiments, the centrifuge tests under 1g and 20 g of gravitational levels were performed with sandy soils sampled from the field, changing the relative density of sandy soil and the ratio of thickness of sand layer (H) to the width of strip footing (B). As results of tests, bearing capacity tends to increase with the value of H/B while settlement for a given load intensity decreases. Bearing capacity also increases with relative density of the soil. In order to propose the method of estimating the bearing capacity of thin sandy layer underlain by a rigid base, values of bearing capacity factors from test results were compared with the values of modified bearing capacity factor by Mandel & Salencon (1972) considering the effect of H/B value on bearing capacity. The relation of bearing capacity factor ratio, normalizing friction angle of sandy soil, with the value of H/B was suggested so that this relation could be applied to design in the safe side. The results of numerical analyses obrained by changing the layout of footing, relative density of sandy soil and the value of H/B, were in good agreements with the suggested relation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1123-1130
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• 2013

This paper aims to estimate work zone base capacity by the number of lanes for urban freeway. To do this, data were collected from the field survey and the database system maintained by traffic control center, and analyzed with four different methods such as the average maximum observation flow rate, headway, regression analysis, and parameter inspection. The work zone base capacity for urban freeway is estimated based on the average maximum observation flow rate and headway method, which are more reliable methods compared to others. The average capacity is 1,650pcphpl when the design speed is 80km/h. The capacity of four lanes one-way work zones was about 1,700pcphpl, while one of 2 lanes one-way work zones was about 1,600pcphpl. The capacity reduction rates for each are 0.15 and 0.2, respectively. The smaller the number of lane is, the more base capacity is reduced. For verification of results, we estimate the capacity by simulation analysis using PARAMICS, and compare with analytical results by a statistical method. This research can be used for efficient and systemic management of work zone in the urban freeway.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.135-143
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• 2004

In the land section of marine bridge construction site, to confirm the end bearing of large diameter drilled shaft constructed in the fault zone which was discovered unexpectedly, the hi-directional end loading tests were performed. The objectives of this study are to confirm the end bearing of the pile constructed in fault zone and the increasing effect of end bearing after grouting the base ground beneath the pile toe. After grouting the pile base ground, the settlement of pile base decreased considerably and the pile base resistance increased more than twice.

• Earthquakes and Structures
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• v.9 no.3
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• pp.639-656
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• 2015

Seismic isolation devices are commonly used to mitigate damages caused by seismic responses of structures. More damages are created due to progressive collapse in structures. Therefore, evaluating the impact of the isolation systems to enhance progressive collapse-resisting capacity is very important. In this study, the effect of lead rubber bearing isolation system to increase the resistance of structures against progressive collapse was evaluated. Concrete moment resisting frames were used in both the fixed and base-isolated model structures. Then, progressive collapse-resisting capacity of frames was investigated using the push down nonlinear static analysis under gravity loads that specified in GSA guideline. Nonlinear dynamic analysis was performed to consider dynamic effects column removal under earthquake. The results of the push down analysis are highly dependent on location of removal column and floor number of buildings. Also, seismic isolation system does not play an effective role in increasing the progressive collapse-resisting capacities of structures under gravity loads. Base isolation helps to localize failures and prevented from spreading it to intact span under seismic loads.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.775-784
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• 2013

Mobile operators are considering a variety of technical measures to cope with the explosion of data while reducing TCO(Total Cost of Ownership) of their networks. In this paper, to investigate the possibility about one of such technical measures, system level simulation to evaluate the performance of the capacity and mobility was performed in cloud base station structure to apply coordinated multi-point transmission and reception. As a result, we find out that system capacity and mobility performance may be improved according to the scale and application area of cloud base station with the operation of coordinated multi-point transmission and reception, and these mutual causality can provide practical guidelines to mobile network's operation.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.3
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• pp.23-30
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• 2019

In this study, we evaluated the applicability of proper embedded depth of fillings by examining the uplift resistance using spiral foundation and top base foundation. As a result of the model test, the maximum uplift resistance increased with the embedded depth. The maximum uplift resistance of each region was found to be 50cm depth. The spiral foundation was 335.14N of Sancheong, 312.32N of Seongju, 403.94N of Wanju, and the top base foundation was 745.06N of Sancheong, 1028.82N of Seongju and 950.76N of Wanju. The yield point after the elastic section in the stress-displacement graph of the top base foundation was calculated as the maximum uplift resistance. For this reason, farmers do not actually use top bases foundation. Therefore, it was considered that the additional load increase due to slip connector will not occur. Model test results show that the maximum uplift resistance increases with the purlinss installed under the ground. Therefore, additional comparative studies through purlins installation will be needed.

• Geomechanics and Engineering
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• v.11 no.3
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• pp.385-400
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• 2016

Bearing capacity of open-ended piles depends largely on inner frictional resistance, which is influenced by the degree of soil plugging. While a fully-plugged open-ended pile produces a bearing capacity similar to a closed-ended pile, fully coring (or unplugged) pile produces a much smaller bearing capacity. In general, open-ended piles are driven under partially-plugged mode. The formation of soil plug may depend on many factors, including wall thickness at the pile tip (or inner pile diameter), sleeve height of the thickened wall at the pile tip and relative density. In this paper, we studied the effects of wall thickness at the pile base and sleeve height of the thickened wall at the pile tip on bearing capacity using laboratory model tests. The tests were conducted on a medium dense sandy ground. The model piles with different tip thicknesses and sleeve heights of thickened wall at the pile tip were tested. The results were also discussed using the incremental filling ratio and plug length ratio, which are generally used to describe the degree of soil plugging. The results showed that the bearing capacity increases with tip thickness. The bearing capacity of piles of smaller sleeve length (e.g., ${\leq}1D$; D is pile outer diameter) was found to be dependent on the sleeve length, while it is independent on the sleeve length of greater than a 1D length. We also found that the soil plug height is dependent on wall thickness at the pile base. The results on the incremental filling ratio revealed that the thinner walled piles produce higher degree of soil plugging at greater penetration depths. The results also revealed that the soil plug height is dependent on sleeve length of up to 2D length and independent beyond a 2D length. The piles of a smaller sleeve length (e.g., ${\leq}1D$) produce higher degree of soil plugging at shallow penetration depths while the piles of a larger sleeve length (e.g., ${\geq}2D$) produce higher degree of soil plugging at greater penetration depths.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.700-703
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• 2004

The purpose of this study is to present the design methodology of base isolated buildings. To achieve the goal of this study, time-history analysis was performed with seismic performance level and recorded seismic data. From the analysis results of MDOF system, the maximum. displacement and base shear were evaluated as 25 cm and $4\%$ by the input level which is maximum velocity of 50 kine. By introducing hybrid isolation system, seismic energy can be concentrated consequently high seismic capacity of the total building is secured.