• Water Engineering Research
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• v.1 no.3
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• pp.171-185
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• 2000

A mathematical model to adequately predict complex mixing characteristics of sorptive polluants in natural streams with pools-and-riffes has been developed. In this model, sorption of pollutants onto the bed sediment as well as mass storage and exchange in the storage zones were incorporated into one-dimensional mass balance equatins. The geometric and hydraulic characteristics of the pool-riffle sequences were properly conceptualized. Simulations with parameters of pool-and-riffle streams better fit the measured data in overall shape and peak concentration than simulations with parameters for uniform channels. The analyses on the characteristics of the storage zone model parameters reveal that a linear relationship between the logrithm of the storage zone volume ratio and a function of the friction factor exists. A linear relatiohship might also be tenatively assumed between the logarithm of the dimensionless mass exchange coefficient and the logarithm of the aspect ratio of the storage zone if some of the high values of the dimensionless mass exchange coefficient collected on the successive bed forms are excluded.

• Journal of Korea Water Resources Association
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• v.36 no.3 s.134
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• pp.385-398
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• 2003

The concept of the effective storage ratio has been suggested to determine the size of detention pond by the previous researchers. The 11 pump - pond facilities in Dongdu-chun city were selected to analyze the critical duration for design rainfall and the storage ratio for each rainfall duration in this study It has been then found that the criteria of the maximum storage ratio is not reasonable for determining the size of detention pond because the difference of storage ratio with respect to each rainfall duration is too small. Moreover, since the size of pond compared with the pump capacity is not always big enough, the pump should be frequently operated, which may result in pump failure. Thus, the pond should be sufficiently sized to prevent the possibility of the pump failure due to frequent operation. According to the analyses for changing pump capacity, it has been found that if the function of the pond compared with the pump is concentrated, determining the size of pond based on the storage ratio is operationally feasible for even small basin. Thus, an improved procedure based on the storage ratio for determining the size of detention pond in small basin has been suggested. The results by the proposed procedure considering pump switching frequency may lead to reasonable pump operation. A simple linear programming model has been also adopted to figure out the relationship between pump capacity and pond size. It has been shown that the determination lot the size of detention pond based on conventional hydrologic flood routing in pond is feasible for only urban districts not rural areas.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.619-624
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• 2005

This work is for examining a simplified equation based on the rational formula, which can easily decide storm-water detention volume in small urban catchments. The storm-water detention volume is determined by the inflow hydrograph flowing to detention basin and the outflow hydrograph discharged from the detention basin. The ratio of average outflow over the period of rainfall duration against allowable discharge was 0.5 in former simplified equation. But this research has found that the average outflow ratio depends on the storage methodology. In the case of the on-line storage method, the average outflow ratio is a function of the time of concentration of the catchments and rainfall duration, which ranged from 0.5~1.0. In the case of the off-line storage method, the average ratio is a function of peak discharge and allowable discharge except above time of concentration and rainfall duration, where its function value ranged from 1.0~2.0. When applying this equation to small catchment in Mokpo city, South Korea, we could easily calculate the relation curve between the storm-water detention volume and allowable discharge.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.2
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• pp.75-80
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• 2002

The severity of drought in (the) irrigation reservoir could be evaluated by the accumulative rainfall method, soil moisture content method, storage ratio method, and water supply restricted intensity method, etc. The storage ratio method would be the most reliable one for irrigation reservoir. The pattern of drought might be forecast with the most similar pattern of accumulative rainfall and/or storage ratio out of the file of past operation history.

• Journal of the Korean Society of Visualization
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• v.19 no.3
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• pp.99-105
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• 2021

In this study, the thermal stratification in solar seasonal thermal storage tanks was numerically simulated. The effects of the aspect ratio (AR) and inlet velocity on the thermal stratification in the diffuser type heat storage tank were investigated. The temperature distributions inside the tank were similar with velocity fields. Jet flows from opposite diffusers encountered each other at the tank center region. Thereafter, the downward flows occurred, and this flows strongly affected the thermal stratification. When AR was smaller than 2, these downward flows influenced a further distance and enhanced mixing inside the tank. Thermal stratification was evaluated by thermocline thickness and degree of stratification, and AR of 3 had the highest degree of stratification. The inlet velocity effect was expressed with the ratio (Re/Ri) of Reynolds and Richardson numbers. The second-order approximation was found for the relationship between the thermocline thickness and log Re/Ri.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1260-1263
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• 2005

Data storage related with writing and retrieving requires high storage capacity, fast transfer rate and less access time. Today any data storage system cannot satisfy these conditions, however holographic data storage system can perform faster data transfer rate because it is a page oriented memory system using volume hologram in writing and retrieving data. System can be constructed without mechanical actuating part therefore fast data transfer rate and high storage capacity about 1Tb/cm3 can be realized. In this research, to reduce errors of binary data stored in holographic data storage system, a new method for bit error reduction is suggested. First, find fuzzy rule using experimental system for Element of Holographic Digital Data System. Second, make fuzzy rule table using Genetic algorithm. Third, reduce prior error element and recording Digital Data. Recording ratio and reconstruction ratio will be very good performance

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2142-2143
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• 2006

Today any data storage system cannot satisfy all of these conditions, however holographic data storage system can perform faster data transfer rate because it is a page oriented memory system using volume hologram in writing and retrieving data. System can be constructed without mechanically actuating part therefore fast data transfer rate and high storage capacity about 1Tb/cm3 can be realized. In this research, to reduce errors of binary data stored in holographic data storage system, a new method for bit error reduction is suggested. Firstly, find fuzzy rule to use test bed system for Element of Holographic Digital Data System. Secondly, make fuzzy rule table using DNA coding method. Finally, reduce prior error element and recording digital data. Recording ratio and reconstruction ratio show good performance.

• Tunnel and Underground Space
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• v.17 no.1 s.66
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• pp.56-65
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• 2007

A new underground LNG storage concept in the rock mass has been developed by combining underground cavern construction and new ice-ring harrier technologies with the conventional cryogenic insulation system. Technical feasibility of the storage system has been verified through construction and operation of the pilot storage cavern and a full-scale project is expected to start in the near future. One of the most important issues in the LNG storage system is the operational efficiency of the storage to minimize heat loss during a long period of operation due to the cryogenic heat transfer. This paper presents several important results of heat transfer and coupled hydro-thermal analyses by a finite element code Temp/W and Seep/W. A series of heat transfer analyses for full-scale caverns were performed to determine design parameters such as boil-off gas ratio (BOR), insulation thickness and pillar width. The result of the coupled hydro-mechanical analysis showed that BOR for underground storage system remains at about 0.04 %/day during the early stage of the operation. This value could be even much lower when the discontinuities in the rock masses are taken into consideration.

• Solar Energy
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• v.9 no.2
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• pp.42-50
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• 1989

The Buoyant Jets were analysed experimentally changing flow rate (0.0291/s, 0.0371/s, 0.0451/s), ratio of nozzle tip area to throat area (aspect ratio ${\beta}$=0.4, 1.0, 1.9), and also the temperature difference (${\Delta}T=Ti-T{\infty}$) between the temperature of the inflow water into the storage tank ($1m{\times}1m{\times}3m$) and the mean temperature of the water in the storage tank were changed as $25^{\circ}C,\;35^{\circ}C$ and $45^{\circ}C$. The more aspect ratio decreased, the more the trajectories of Buoyant Jets center-line were decreased and not the more the trajectories of Buoyant Jets centerline were influenced by the increment of the difference of the temperature. The more aspect ratio decreased, the more the half widths and dilution ratio of Buoyant Jets were increased and not the more the half widths and dilution ratio of Buoyant Jets were influenced by the increment of the difference of the temperature. Fr number is the factor that can predict the flow pattern over the whole flow field. And yet for the consideration the near field of Buoyant Jets flow pattern is dominated by magnitude of momentum and buoyancy force.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.5
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• pp.73-80
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• 1995

The uses of stage-storage curve function are diverse in irrigation reservoirs. The curve functions would be used to determine the optimal size of spillway length and the inundation area above full water level based on the flood routing in reservoirs. In addition, the curve function would he used to transform the stage to the storage for the reservoir water management, in which the storage is the supply water. Besides those, the curve is necessary for the planning of dredging, the estimation of the effective and the dead storage, the drought management by reservoir, etc. The curve function data, however, are almost unavailable for these purposes. According to the statistics, about 74% of the 2, 900 resevoirs which are maintained by Farm Land Improvement Association have no more effective data. Therefore, the simulation of the curve function could be better alternative. The curve functions were simulated derivating the regression equations based on the basin relief ratio and the effective depth. The results of the verification show the enough reliability of the application to generate the curve function in some reservoirs which do not have the surveyed stage-storage data. Also, even though the averaged curve function would be applicated without the basin relief ratio data, the result shows that the simulated curve is closer to the real one than the linear function by only the existing effective storage data.