• Water for future
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• v.17 no.2
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• pp.125-131
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• 1984

watershed Model by mathematical formulation is one of the powerful tool to analyze the hydrologic process in a watershed. The seasonal watershed model is one of the mathematial model from which the monthly streamflow can be simulated and forcasted for given precipitaion data. This model also enables us to compute the monthly runoff at each subbgasin when the basin is subdivided into several small subbasins. The computation of runoff volume makes a Prediction of the areal distirbution of runoff volume for a given precipitation data. Several basins in Han River basin were chosen to simulate the monthly runoff and compute the runoff at each subbasin. A simple logarithmic regression were conducted between runoff ratio and area ratio. The correlation was very high and the equation can be used for prediciting flood volume when flood at downstream gaging station is know.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.841-850
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• 1997

A simple molecular theory of mixtures is formulated based on the nonrandom two-fluid lattice-hole theory of fluids. The model is applicable to mixtures over a density range from zero to liquid density. Pure fluids can be completely characterized with only two molecular parameters and an additional binary interaction energy is required for a binary mixture. The thermodynamic properties of ternary and higher order mixtures are completely defined in terms of the pure fluid parameters and the binary interaction energies. The Quantitative prediction of vapor-liquid, and solid-vapor equilibria of various mixtures are demonstrated. The model is useful, in particular, for mixtures whose molecules differ greatly in size. For real mixtures, satisfactory agreements are resulted from experiment. Also, the equation of state (EOS) is characterized well, even the liquid-liquid equilibria behaviors of organic mixtures and polymer solutions with a temperature-dependent binary interaction energy parameter.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.466-471
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• 2005

The out-of-plane deformation in thin plate structure has been a serious qualify problem. It has been known that the out-of-plane deformation is caused by the angular deformation of welded joint. However, experimental results show that the conventional theory based on angular deformation is not appropriate for prediction of the out-of-plane deformation in thin plate structure. In this study, large deformation plate theory is introduced to clarify the effect of residual stress on the out-of-plane deformation. A simple equation is proposed to predict the out-of-plane deformation. The results by the proposed method show good agreement with the experimental results.

• Korean Journal of Environmental Agriculture
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• v.11 no.1
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• pp.20-25
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• 1992

To understand the fundamental features of reservoir environment and its future aspects, a simple predictive model for water quality was attempted with the aid of data easily obtained, Based on the data from 12 reservoirs in Korea, application of the simple predictive model was successfully made by means of statistical methods and simple physical submodels. Significant information on th effects of retention time on primary production in a reservoir, longitudinal change in water quality affected by certain non-dimensional parameters were also obtained. The chlorophyll-a concentration can be predicted by the equation as ; chlorophyll-a=($395{\time}limiting$ nutrient concentration) - 1.090.

• Journal of Biomedical Engineering Research
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• v.14 no.1
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• pp.89-96
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• 1993

During high frequency ventilation (HFV), mean alveolar pressure has been measured to increase with mean airway opening pressure controlled at a constant level in both humans and experimental animals. Since this phenomenon could potentiate barotrauma limiting advantages of HFV, the present study theoretically predicted the difference between menu alveolar and airway opening pressures ($MP_{alv}$). In a Weibel's trumpet airway model, approximated formula for $MP_{alv}$ was derived based on momentum conservation assuming a uniform velocity profile. The prediction, equation was a func pion of gas density($\rho$), mean flow rate(Q), and diameter of the airway opening where the pressure measurement was made($D_0$) : $MP_{alv}=4{\rho}(Q/D_0^{2})^2$. This was a result of the difference in crosssectional area between the alveoli and the airway opening. A simple aireway model experiment was performed and the results well fitted to the prediction, which demonstrated the validity of the present analysis. Previously reported $MP_{alv}$ data from anesthetized dogs in supine position were comparable to the predicted values, indicating that the observed dissociation between mean alveolar and airway opening pressures during HFV can be explained by this innate geometric (or cross-sectional area) asymmetry of the airways. In lateral position, however, the prediction substantially underestimated the measurements suggesting involvement of other important physiological mechanisms.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.6
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• pp.98-106
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• 2011

This paper reviews the state-of-the-art thermoacoustic(TA) modeling techniques and research trend to predict major parameters determining combustion instabilities in lean premixed gas turbine combustors. Linear TA modeling results give us an information on eigenfrequencies and initial growth rate of the instabilities. For the prediction, linear relation equation between acoustic waves and heat release oscillations should be derived in the determined system. Key information for this analysis is to determine the heat release fluctuations in the combustor, which is typically obtained by using n-${\tau}$ function from flame transfer function measurements and/or predictions. Great advancement in the linear TA modeling has been made over a couple of decades, and some successful prediction results have been reported in actual gas turbine combustors. However nonlinear TA model developments which are required to analyze nonlinear system behaviors such as limit cycle saturation and transition phenomena are still limited in a very simple system. In order to fully understand combustion instabilities in a complicated real system, nonlinear flame dynamics and acoustic wave interaction with nonlinear system boundary conditions should be explained from the nonlinear TA model developments.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.9
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• pp.897-901
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• 2011

This paper presents a TS (Takagi-Sugeno) type FLC (Fuzzy Logic Controller) with only 3 rules. The choice of parameters of FLC is very difficult job on design FLC controller. Therefore, the choice of appropriate linguistic variable is an important part of the design of fuzzy controller. However, since fuzzy controller is nonlinear, it is difficult to analyze mathematically the affection of the linguistic variable. So this choice is depend on the expert's experience and trial and error method. In the design of the system, we use a variety of response characteristics like stability, rising time, overshoot, settling time, steady-state error. In particular, it is important for a stable system design to predict the steady-state error because the system's steady-state response of the system is related to the overall quality. In this paper, we propose the method to choose the consequence linear equation's parameter of T-S type FLC in the view of steady-state error. The parameters of consequence linear equations of FLC are tuned according to the system error that is the input of FLC. The full equation of T-S type FLC is presented and using this equation, the relation between output and parameters can represented. As well as the FLC parameters of consequence linear equations affect the stability of the system, it also affects the steady-state error. In this study, The system according to the parameter of consequence linear equations of FLC predict the steady-state error and the method to remove the system's steady-state error is proposed using the prediction error value. The simulation is carried out to determine the usefulness of the proposed method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.161-168
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• 2015

Horizontally curved bridges are subjected to torsional loads by their vertical dead loads only as well as eccentric loads, which cause negative reactions at supports. In this paper, effects of bridge curvature on vertical reactions at supports are investigated for 48.8 m length simple span steel box girder bridges with elastomeric bearings by varying curvature angle from 0.49 to 1.35 rad. In order to expect magnitude and direction of reactions including possibility of negative reactions, reaction evaluation equations have been analytically developed by separating a superstructure of curved bridge into independent components. Concrete slabs and bottom flanges in steel box section are assumed geometrical annular sectors in area dimension, and top flanges and webs that have very narrow projected areas are assumed geometrical arcs in line dimension. Proposed equations have relatively simple forms and prediction values are on very good agreement with those from finite element analyses by difference of 1% order.

• International Journal of Automotive Technology
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• v.5 no.3
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• pp.215-219
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• 2004

A vehicle structure needs to be more precisely analyzed because of complexities and varieties. Structural fatigue which is generated by fluctuations of stresses during the service life of a mechanical system is the primary concern in the structural design for safety. A fatigue life is difficult to obtain in structural components during the service life of mechanical systems since the fluctuating stress contributes to fatigue. This study introduces new procedures to measure the lethargy coefficient and to predict the fatigue life of a mechanical structure by using molecular dynamic simulation. A lethargy coefficient is the total defect-estimating coefficient, which was obtained by using the results of a simple tensile test in this study. With this lethargy coefficient, fatigue life was estimated. The proposed method will be useful in predicting the fatigue life of a structurally-modified vehicle design. The effectiveness of the proposed method using lethargy coefficient measurement to predict the fatigue life of a structure was examined by applying this method to predict the fatigue life of SS41 steel, used extensively as material of vehicle structures. Two types of specimen such as pre-cracked plate and simple plate is discussed. equation of fatigue life using the lethargy coefficient and failure time, both obtained from a simple tensile test, will be useful in engineering. This measurement and prediction technology will be extended for use in analysis of any geometric shapes of modified automotive structures.

• Tunnel and Underground Space
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• v.17 no.5
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• pp.372-380
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• 2007

Surface damage due to subsidence is an inevitable consequence of underground mining, which may be immediate or delayed for many years. The surface damage due to abandoned underground mine is observed to be two subsidence types such as simple sinkhole or trough formation to a large scale sliding of the ground from with in the subsided area. An evaluation of the risk of a subsidence occurrence is vital in the areas affected by mining subsidence. For a subsidence prediction or a risk evaluation, there has been used various methods using empirical models, profile functions, influence functions and numerical models. In this study, a simple but efficient evaluation method of subsidence hazard is suggested, which is based on a diffusion theory and uses just information about geometry of caving and topography. The diffusion model has an analogous relationship with granular model which can explain a mechanism of subsidence. The diffusion model is applied for the evaluation of subsidence hazard in abandoned metal and coal mines. The model is found to be a simple but efficient tool because it needs information of geometry of caving and gangway and the topography.