• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.303-314
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• 2009

The present paper shows the results of numerical and experimental modal analyses of Francis runners, which were executed in air and in still water. In its first part this paper is focused on the numerical prediction of the model parameters by means of FEM and the validation of the FEM method. Influences of different geometries on modal parameters and frequency reduction ratio (FRR), which is the ratio of the natural frequencies in water and the corresponding natural frequencies in air, are investigated for two different runners, one prototype and one model runner. The results of the analyses indicate very good agreement between experiment and simulation. Particularly the frequency reduction ratios derived from simulation are found to agree very well with the values derived from experiment. In order to identify sensitivity of the structural properties several parameters such as material properties, different model scale and different hub geometries are numerically investigated. In its second part, a harmonic response analysis is shown for a Francis runner by applying the time dependent pressure distribution resulting from an unsteady CFD simulation to the mechanical structure. Thus, the data gained by modern CFD simulation are being fully utilized for the structural design based on life time analysis. With this new approach a more precise prediction of turbine loading and its effect on turbine life cycle is possible allowing better turbine designs to be developed.

• Computers and Concrete
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• v.5 no.1
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• pp.1-20
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• 2008

In this study, the effects and the interactions of water content, SP-binder ratio, and water-binder ratio on the workability performance of concrete were investigated. The experiments were designed based on flatted simplex-centroid experiment design modified from standard simplex-centroid one. The data gotten from the design was used to build the concrete slump model using neural networks. Research reported in this paper shows that a small number of slump experiments can be performed and meaningful data obtained with the experiment design. Such data would be suitable for building slump model using neural networks. The trained network can be satisfactorily used for exploring the effects of the components and their interactions on the workability of concrete. It has found that a high water content and a high SP/b ratio is essential for high workability, but achieving this by increasing these parameters will not in itself guarantee high workability. The w/b played a very important role in producing workability and had rather profound effects; however, the medium value about 0.4 is the best w/b to reach high slump without too much effort on trying to find the appropriate water content and SP/b.

• Fire Science and Engineering
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• v.23 no.5
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• pp.84-89
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• 2009

In this study, the fire extinguishing experiment was performed using a water mist nozzle with variation of factors which affect on the extinguishing time. The variables were distance from nozzle center to fire location, droplet size, height of nozzle and opening or not. With the experimental data, interaction and sensitivity between factors were analysed with Mini tab and deduce a optimum model of fire extinguishing of water mist system. Based on the experiment and modeling of fire extinguishing with water mist system, the most important factor on extinguishing time is the distance from the center of nozzle to fire and the opening effect was small compare with other factors.

• Journal of Korea Water Resources Association
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• v.44 no.6
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• pp.461-470
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• 2011

Abrupt and gradual levee breach analyses on the flat domain were implemented by laboratory experiments and numerical simulations. To avoid the reflective wave from the side wall the experiment was performed in a large domain surrounded by waterway. A numerical model was developed for solving the two-dimensional gradual levee breach flow. The results of the numerical simulation developed in this study showed good agreement with those of the experimental data. However, even if the numerical schemes effectively replicated the trends of the observed water depth for the first shock, there were little differences for the second shock. In addition, even though the model considered the Smagorinsky horizontal eddy viscosity, the location and height of the hydraulic jump in the numerical simulation were not fairly well agree with experimental measurements. This shows the shallow water equation solver has a limitation which does not exactly reproduce the energy dissipation from the hydraulic jump. Further study might be required, considering the energy dissipation due to the hydraulic jump or transition flow from reflective wave.

• New & Renewable Energy
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• v.4 no.2
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• pp.94-104
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• 2008

The change of water discharge capability of sluice caisson for tidal power plant according to installation of the rubble mound was investigated by performing laboratory experiment. The experiment was carried out in an open channel flume with a great care to measure flow rate and water level in the flume accurately. Eight different sluice caisson models were used in the experiment. The water discharge capabilities of seven sluice models decreased with respect to the placement of the rubble mound, while increased for only one sluice model. On average, the values of discharge coefficient decreased by approximately 10% when the sluice models were placed on the rubble mound. It is concluded that the shape of the rubble mound can affect the water discharge capability of the sluice caisson, so that its shape should be significantly considered in the design of the sluice caisson, especially when it is deployed in a site of relatively deeper depth.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1888-1893
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• 1991

Systematic design of a controller for a water temperature system was considered, with the intention of devising an accurate control experiment. The results of an experiment using a water temperature system based on the pole placement regulator showed water temperature oscillation and steady state error. This paper proposed a. method for eliminating both the oscillation and the steady state error. The oscillation was eliminated by a drive delay compensation technique, in which a future state value of the system was predicted through a real time computer simulation. The steady state error was eliminated by an steady state error correction technique, in which an actual steady state heatrate in the system model was replaced by an imaginary heatrate. By combining these two techniques, we obtained an experimental result for water temperature control of 0.01 (.deg. C) accuracy. Furthermore, the proposed method was evaluated relatively by comparing the experimental results using several other methods and proved to be the most accurate and convenient control method for the delay system.

• Journal of the Korean Geotechnical Society
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• v.27 no.4
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• pp.43-50
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• 2011

Steel-making slag was investigated as reactive material for removal of cadmium in coastal area. Batch experiments of the sorption isotherm experiment and kinetic sorption experiment were performed. Result of sorption isotherm was more adequately described by Langmuir model than Freundlich model and theoretical maximum capacity (${\beta}$) of cadmium onto steel-making slag was found. Results of kinetic sorption experiments were evaluated by pseudo second order model to investigate sorption characteristics of cadmium onto steel-making slag. Results showed that the equilibrium sorption amount of cadmium (q$q_e$) increased and the rate constant ($k_2$) and initial sorption rate (h) decreased as the initial cadmium concentration increased. The $q_e$ with simulated sea water was similar to that with deionized water and $k_2$ and h with simulated sea water was lower than those with deionized water. Results of kinetic experiments could be used to predict the result from sorption isotherm, since equilibrium sorption amounts calculated by pseudo second order model generally agreed with those measured from sorption isotherm. The reaction time for the target removal rate could be calculated by the pseudo second order model using kinetic sorption tests results.

• Magazine of the Korean Society of Agricultural Engineers
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• v.12 no.4
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• pp.2090-2123
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• 1970

This paper is a report on the research of experimental model test of Andong Fill Dam, which has been planned by the Government of Korea as a project, of its over-flowing capacity in spillway, creation of minus pressure and structure of anti-water impulse in over-flow weir. Andong Fill Dam is one of the project of master development plant for water resources, locating at Nakdong River side of Korea, and is aimed to have a multi-purpose dam for flood-control, irrigation, water power, urban and industrial water supply. This dam is planned to erect in fill-dam type due to the improper soil foundation and condition for concrete dam. The refore for the proper and advantageous points, this is designed as center core fill dam. By a model minimized of Andong Fill Dam, held an experimental model test on water quentity of reservir, discharges of overflow part, low pressure and anti-water impulse of overflow part, which was conducted an experiment by flowing aspects through each section of spillway to find the changes of water pressure and that of water level, and corrected the section of each part in order to conduct a check on the creation of minus pressure not to be over acted to the allowable bundary of the section structure; and for the prevention of concentated scouring at the down stream side of flow.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1313-1317
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• 2006

In this study, various hydraulic phenomena were analyzed from the dam model experiments and the analyzed results were compared with existing computation results. Sungduk dam model structures were constructed using Froude similarity law by 1:50 scale. From the measurements of hydraulic phenomena at spillway channel, an improvement method was trying to be suggested over shortcoming of existing design plan. The result of model experiment showed no big difference with that of each part's numerical interpretation. Sidewall overflows were observed, as water conveyance occurred due to the linear characteristics of spillways, which raised the necessity for improving the linear forms of spillways. Also, it was judged to be necessary improving load pressure and establishing protective structures at the riverbed grounds of downstream channels.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.253-254
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• 2012

In this study, it carried out measurement experiment Ca(OH)₂ and chemically bound water to verify Ca(OH)₂ and chemically bound water prediction model out of hydration model of cement incorporating blast furnace slag. It compared and analyzed prediction results using prediction model with measurement results of Ca(OH)₂ quantity using thermogravimetric differential temperature analysis and chemically bound water quantity using electronic furnace. It agrees well experiments results with prediction results.