• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.329-338
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• 2019

Suction of unsaturated bentonite buffers is a very important input parameter for hydro-mechanical performance assessment and design of an engineered barrier system. This study analyzed suction measurement techniques and constitutive models of unsaturated porous media reported in the literature, and suggested suction measurement techniques and constitutive models suitable for bentonite buffer in an HLW repository. The literature review showed the suction of bentonite buffer to be much higher than that of soil, as measured by total suction including matric suction and osmotic suction. The measurement methods (RH-Cell, RH-Cell/Sensor) using a relative humidity sensor were suitable for suction measurement of the bentonite buffer; the RH-Cell /Sensor method was more preferred in consideration of the temperature change due to radioactive decay heat and measurement time. Various water retention models of bentonite buffers have been proposed through experiments, but the van Genuchten model is mainly used as a constitutive model of hydro-mechanical performance assessment of unsaturated buffers. The water characteristic curve of bentonite buffers showed different tendencies according to bentonite type, dry density, temperature, salinity, sample state and hysteresis. Selection of water retention models and determination of model input parameters should consider the effects of these controlling factors so as to improve overall reliability.

• Proceedings of the IEEK Conference
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• 2001.06c
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• pp.85-86
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• 2001

3D parallel rasterizer on a single chip for high performance generates consistency problem. To solve this problem, 3D parallel rasterizer with consistency buffer Os proposed. This can simultaneously process a plurality of Primitives. Experimental results show 1.1-2.0x speedups using a simple model. This method can achieve high performance and cost effectiveness.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.561-564
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• 1998

This paper describes a performance degradation of static type input buffer due to the device degradation in menory devices using $0.8\mu\textrm{m}$ CMOS process. experimental results shows that the degradation of MOS device affects the Trip Point shift in static type input buffer. We have performed the spice simulation and calculated the Trip Point with model parameter and measurement data so that how much the Trip Point(VLT) variate.

• Journal of applied mathematics & informatics
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• v.5 no.3
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• pp.643-658
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• 1998

In this paper we analyze the performance of a statistical ATM multiplexer with bursty input traffic and two thresholds in the buffer by using queueing model. Two priority levels are considered for source traffic which is modeled by Markov Modulated Poisson Process to represent the bursty characteristics. Service time distributions of two priority sources are assumed to be same and deterministic for ATM environment. The partial buffer sharing scheme with one threshold may experience a sensitive state change around the threshold. But the proposed multiplexer with two thresholds avoids this hysterical phenominon to improve the system operation.

• IE interfaces
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• v.14 no.4
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• pp.334-340
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• 2001

The theory of constraints (TOC) has become a valuable system in modern operations management. Using the ideas and methods of the TOC, companies can achieve a large reduction of work-in-process and finished-goods inventories, significant improvement in scheduling performance, and substantial earnings increase. The purpose of this paper is to calculate the optimal size of the time buffer which is used to accommodate disruptions in production processes and provide maximum productivity of capacity constrained resources. After the problem formulation in terms of single server queueing model, we observed the system behavior by sensitivity analyses.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.476-480
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• 2002

The theory of constraints (TOC) has become a valuable system in modern operations management. Using the ideas and methods of the TOC, companies can achieve a large reduction of work-in-process and finished-goods inventories, significant improvement in scheduling performance, and substantial earnings increase. The purpose of this paper is to calculate the optimal size of the time buffer which is used to accommodate disruptions in production processes and provide maximum productivity of capacity constrained resources. After the problem formulation in terms of single server queueing model, we observed the system behavior by sensitivity analyses.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1976-1985
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• 2015

The amount of packets in palyout buffer of video streaming receiver can be changed by network condition, and saturated and exhausted by the delay and jitter. Especially, if the amount of incoming video traffic exceeds the maximum allowed playout buffer, buffer overflow problem can be generated. It makes the deterioration of video image and the discontinuity of playout by skip phenomenon. Also, if the incoming packets are delayed by network confusion, the stop phenomenon of video image is made by buffering due to buffer underflow problem. To solve these problems, this paper proposes the video streaming receiver with token bucket scheme which automatically establishes the important parameters like token generation rate r and bucket maximum capacity c adapting to the pattern of video packets. The simulation results using network simulator-2 (NS-2) and joint scalable video model (JSVM) show that the proposed token bucket scheme with automatic establishment parameter provides better performance than the existing token bucket scheme with manual establishment parameter in terms of the generation number of overflow and underflow, packer loss rate, and peak signal to noise ratio (PSNR) in three test video sequences.

• Journal of the Korean Geotechnical Society
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• v.33 no.7
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• pp.55-64
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• 2017

A geological repository has been considered one of the most adequate options for the disposal of high-level radioactive waste. A geological repository will be constructed in a host rock at a depth of 500~1,000 meters below the ground surface. The geological repository system consists of a disposal canister with packed spent fuel, buffer material, backfill material, and intact rock. The buffer is very important to assure the disposal safety of high-level radioactive waste. It can restrain the release of radionuclide and protect the canister from the inflow of groundwater. High temperature in a disposal canister is released into the surrounding buffer material, and thus the thermal transfer behavior of the buffer material is very important to analyze the entire disposal safety. Therefore, this paper presents a thermal conductivity prediction model for the Kyungju compacted bentonite buffer material which is the only bentonite produced in Korea. Thermal conductivity of Kyungju bentonite was measured using a hot wire method according to various water contents and dry densities. With 39 data obtained by the hot wire method, a regression model to predict the thermal conductivity of Kyungju bentonite was suggested.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.5
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• pp.481-491
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• 2014

In this paper, we discussed a problem for improving the throughput of a crankshaft manufacturing line in an automotive factory in which the budget for purchasing new machines and installing additional buffers is limited. We also considered the constraint of available space for both of machine and buffer. Although this problem seems like a kind of buffer allocation problem, it is different from buffer allocation problem because additional machines are also considered. Thus, it is not easy to calculate the throughput by mathematical model, and therefore simulation model was developed using $ARENA^{(R)}$ for estimating throughput. To determine the investment plan, a modified Arrow Assignment Rule under some constraints was suggested and it was applied to the real case.

• Environmental Engineering Research
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• v.25 no.1
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• pp.123-128
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• 2020

Non-point source pollutant load reductions were calculated using the Hydrologic Simulation Program-Fortran (HSPF) model under the assumption that landuse pattern was changed according to land purchases. Upon the simulation of non-point pollutant and areas with high land purchase ratios to select a buffer zone, the Namgang dam Reach 11, Imha dam Reach 10, and the Reach 136 watershed of the main river were found to rank high for the construction of buffer zones. Assuming that the forms of the purchased lands were changed to wetlands, biological oxygen demand (BOD) loads were changed through the HSPF model. No changes of BOD were present in the Namgang dam and the Imha dam watersheds. BOD loads in Reach 136 according to landuse change were analyzed through a flow duration analysis based on the total maximum daily loads of the United States. The flow duration analyses undertaken to examine changes in BOD of main river Reach 136 watershed indicated a shift of 0.64 kg/d from 3.16 to 2.52 during high flow. The change of BOD under the conditions of moist, mid-range and dry were 11.9%, 9% and 4.5%. At the low flow condition, the variation range in the BOD load was from 0.58 kg/d to 0.41 kg/d.