• Earthquakes and Structures
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• v.9 no.1
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• pp.195-219
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• 2015

A partial (hybrid) seismic isolation scheme for precast girder bridges in the form of a "buffer-gap-elastomeric bearings" system has been endorsed in the literature as an efficient seismic design system. However, no guides exist to detail an optimal gap size for different configurations. A numerical study is established herein for different scenarios according to Euro code seismic requirements in order to develop guidelines for the selection of optimal buffer-gap arrangements for various design cases. Various schemes are hence designed for ductile and limited ductility behavior of the bridge piers for different seismic demand levels. Seven real ground records are selected to perform incremental dynamic analysis of the bridges up to failure. Bridges with typical short and high piers are studied; and different values of initial gaps at piers are also investigated varying from a zero gap (i.e., fully locked) condition up to an initial gap at piers that is three quarters the gap left at abutments. Among the main conclusions is that the as-built initial gaps at piers (and especially large gap sizes that are ${\geq}1/2$ as-built gaps at abutments) do not practically reduce the seismic design demand and do not affect the reserve capacity of the bridge against failure for bridges featuring long piers, especially when these bridges are designed a priori for ductile behavior. To the contrary, the "buffer-gap-elastomeric bearings" system is more effective for the bridge schemes with short piers having a large difference between the stiffness of the bearings and that of their supporting (much stiffer) squat piers, particularly for designs with limited ductility. Such effectiveness is even amplified for the case of larger initial as-built gap sizes at piers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.3159-3176
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• 2014

This work presents an analysis of the buffer features of an access router, especially the size, the impact on delay and the packet loss rate. In particular, we study how these features can affect the Quality of Service (QoS) of multimedia applications when generating traffic bursts in local networks. First, we show how in a typical SME (Small and Medium Enterprise) network in which several multimedia flows (VoIP, videoconferencing and video surveillance) share access, the upgrade of the bandwidth of the internal network may cause the appearance of a significant amount of packet loss caused by buffer overflow. Secondly, the study shows that the bursty nature of the traffic in some applications traffic (video surveillance) may impair their QoS and that of other services (VoIP and videoconferencing), especially when a certain number of bursts overlap. Various tests have been developed with the aim of characterizing the problems that may appear when network capacity is increased in these scenarios. In some cases, especially when applications generating bursty traffic are present, increasing the network speed may lead to a deterioration in the quality. It has been found that the cause of this quality degradation is buffer overflow, which depends on the bandwidth relationship between the access and the internal networks. Besides, it has been necessary to describe the packet loss distribution by means of a histogram since, although most of the communications present good QoS results, a few of them have worse outcomes. Finally, in order to complete the study we present the MOS results for VoIP calculated from the delay and packet loss rate.

• Journal of Environmental Science International
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• v.11 no.8
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• pp.773-781
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• 2002

The natural carbon cycle has been perturbed since the mid-19th century by anthropogenic CO$_2$emissions from fossil fuel combustion and deforestation due to population growth and industrialization. The current study simulated the global carbon cycle for the past 42 years using an eight-box carbon cycle model. The results showed that since the terrestrial biospheric carbon sink was roughly offset by the deforestation source, the fossil fuel emission source was partitioned between the atmospheric and oceanic sinks. However, the partitioning ratio between the atmosphere and the ocean exhibited a change, that is, the carbon accumulation rate was faster in the atmosphere than in the ocean, due to a decrease in the so-called ocean buffering capacity. It was found that the ocean buffering capacity to take up excess CO$_2$decreased by 50% in terms of the buffer factor over the past 42 years. Accordingly, these results indicate that if the current CO$_2$emission trend continues, the future rate of increase in the atmospheric CO$_2$concentration will accelerate.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.173-177
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• 2006

Pesticides from diffuse pollution sources adsorbed in suspended particles flow into surface water and threats to the public health. In this research, dechlorination constants of Atrazine by zero valent iron were measured with addition of buffer solution for simulating buffer capacity of sediment. When initial concentration of Atrazine was 10, 30, and 50 mg/L, their dechlorination was explained using the pseudo-first order reaction. Dechlorination constants $K_{obs}$ were $3.21{\times}10^{-2}/d$ in average.

• Journal of the Korea Society for Simulation
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• v.24 no.2
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• pp.11-17
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• 2015

Although systems with finite capacities have been the topic of much study, there are as of yet no analytic expressions for (higher) moment and tail probability of stationary waiting times in systems with even constant processing times. The normal queueing theory cannot properly handle such systems due to the difficulties caused by finite capacity. In this study, for a DBR (Drum-Buffer-Rope) line production system with constant processing times, we introduce analytic expressions by using previous results obtained using a max-plus algebraic approach.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.3
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• pp.17-28
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• 2003

The objective of this study is to review and verify whether the functions and effect of roadside trees generally known in theory are actually realized in urban roads and how well they are performed if the function and effect are really realized. The study was conducted with a focus on air purification effect of roadside trees. The m헤r study result is as follows. First, calculation of air purification effect of roadside trees showed that it is minimal. However, 7.4 units of broad-leaved trees is necessary in order to purify $SO_2$ discharged by one passenger car and 1,803.3 trees to purify $NO_2$. Second, regarding pollutant absorption capacity, air pollutant absorption capacity increased as the number of rows planted gets higher (i.e., 2-row plantation absorbs pollutant better than I-row plantation). In particular, "2-row plantation + lower-level shrub + buffer green belt" was as eight times high as "I-row plantation" in absorption capacity. Third, out of 30 roads with over 8 lanes in 15 cities, only 33.3% or a total of ten roads in seven cities had a median strip. Out of these ten roads, nine roads were planted in a double-layer consisting forest trees, shrubs, ground plants (grass). Analysis showed that out of six tree species planted along these roads, about a half of them were weak to air pollution. Also, based on the outcome of this study, charging a "plantation due" when people purchase a new car, improving layout of roadside trees, and reinforcing plantation of air purification tree species when selecting tree species for roadside trees were proposed.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.2
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• pp.134-145
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• 2004

With rapid growth in the amount of data transferred on the Internet, traditional storage systems have reached the limits of their capacity and performance. SAN (Storage Area Network), which connects hosts to disk with the Fibre Channel switches, provides one of the powerful solutions to scale the data storage and servers. In this environment, the maintenance of data consistency among hosts is an important issue because multiple hosts share the files on disks attached to the SAN. To preserve data consistency, each host can execute the disk I/O whenever disk read and write operations are requested. However, frequent disk I/O requests cause the deterioration of the overall performance of a SAN cluster. In this paper, we introduce a SANtopia global buffer manager to improve the performance of a SAN cluster reducing the number of disk I/Os. We describe the design and algorithms of the SANtopia global buffer manager, which provides a buffer cache sharing mechanism among the hosts in the SAN cluster. Micro-benchmark results to measure the performance of block I/O operations show that the global buffer manager achieves speed-up by the factor of 1.8-12.8 compared with the existing method using disk I/O operations. Also, File system micro-benchmark results show that SANtopia file system with the global buffer manager improves performance by the factor of 1.06 in case of directories and 1.14 in case of files compared with the file system without a global buffer manager.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.5
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• pp.94-103
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• 1997

It is necesary that analog buffer circuit should drive an external load in the VLSI design such as switched capacitor efilter (SCF), D/A converter, A/d converter, telecommunicatin circuit, etc. The conventional CMOS buffer circuit have many probvlems according as CMOS technique. Firstly, Capacity of large load ar enot able to opeate well. The problem can be solve to use class AB stages. But large load are operated a difficult, because an element of existing CMOS has a quadratic functional relation with inptu and outut voltage versus output current. Secondly, whole circuit of dynamic rang edecrease, because a range of inpt and output voltages go down according as increasing of intergration rate drop supply voltage. In this paper suggests that new differential CMOS line driver make out of operating an external of large load. In telecommunication's chip case transmission line could be a load. It is necessary that a load operate line driver. The proposal circuit is planned to hav ea high generation power rnage of voltage with preservin linearity. And circuit of capability is inspected through simulation program (HSPICE).

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.4
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• pp.201-207
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• 2012

Currently, NAND Flash memory has been widely used in consumer storage devices due to its non-volatility, stability, economical feasibility, low power usage, durability, and high density. However, a high capacity of NAND flash memory causes the high power consumption and the low performance. In the convention memory research, a hierarchical filter mechanism can archive an effective performance improvement in terms of the power consumption. In order to attain the best filter structure for NAND flash memory, we selected a direct-mapped filter, a victim filter, a fully associative filter and a 4-way set associative filter for comparison in the performance analysis. According to the results of the simulation, the fully associative filter buffer with a 128byte fetching size can obtain the bet performance compared to another filter structures, and it can reduce the energy*delay product(EDP) by about 93% compared to the conventional NAND Flash memory.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.179-186
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• 2006

There was a lot of research to integration of the transshipment and inventory problem in supply chain. Such a integration of inventory and transshipment problem called IRP (Inventory Routing Problem). We consider a distribution problem in which a set of products has to be shipped from a supplier to several retailers in a given planning horizon. Transshipment from the supplier to the retailer is performed by vehicles of limited capacity. Each retailer determines replenishment leadtime and order quantity with buffer management. A supplier determines optimal vehicle routing in supply chain. We suggest a heuristic algorithm which be used TOC buffer management in a replenishment problem and a tabu search algorithm in VRP (Vehicle Routing Problem).