• 오토저널
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• 제13권1호
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• pp.66-74
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• 1991

A multidimensional numerical simulation of turbulent combustion in a constant volume bomb is implemented to clarify the effects of swirl on combustion. This simulation includes the ICED-ALE numerical technique, the skew-upwind differencing scheme, the modified .Kappa.-.epsilon. turbulence model, and the combustion model of the Arrhenius type and the turbulence-mixing-control type. The calculations of the turbulent combustion with swirl are carried out. It shows that the results agree with the measurements allowably. Therefore, the effects of swirl on turbulent combustion are examined through the parametric study of swirl.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.126-131
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• 2004

Pressure-based 알고리듬을 기반으로 한 cavitation 현상의 수치해석 코드를 개발하였다. Wall function을 사용한 k-\varepsilon$ 난류모델을 사용하였으며, cavitation 모델에는 volume transport equation을 사용하였다. 유동장은 저속이기 때문에 압축성 효과는 고려하지 않았다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2006년도 춘계학술발표회 논문집
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• pp.533-540
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• 2006

In recent years, civil-engineering work is desired the terrain information to be more efficient in earthwork volume calculation. One method for collecting elevation data is LiDAR. Lidar data was used to produce rapidly an accurate digital elevation model of the terrain, compared with the conventional ground surveys, photogrammetty, and remote sensing. Raw Lidar data is combined with GPS positional data to georeference the data sets. Lidar data is edited and processed to generate surface models, elevation models, and contours. Here we can either create a Tin Volume Surface or a Gird Volume Surface. Triangulated Irregular Network(TIN) has complex data structure, but it can describe well terrain surface features. As we have seen, we search the efficiency for earthwork volume calculation using Lidar data. One conclusion we can draw from this study is that Lidar data is more accurate result than digital map in the calculation of earthwork volume.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.47-54
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• 1999

A method is developed to include the effect of volume expansion in the description of the flame dynamics using G-equation. Line volume-source is used to represent the effect of the exothermic process of combustion with source strength assigned by the density difference between the burned and the unburned region. The present model provides good agreement with the experimental results by using realistic volume expansion ratio which was not reached in the previous researches. Including volume expansion, the flow predicts the same behavior of measured velocity field qualitatively. The flame propagation in varying flow field due to volume expansion provides a promising way to represent the wrinkled turbulent premixed flames in a numerically efficient manner.

• 한국방재학회 논문집
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• 제8권3호
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• pp.105-115
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• 2008

도시화로 인한 유출량의 증가 및 도달시간의 단축은 도시재해의 한 원인이 되고 있다. 이를 막기 위하여 도시 배수유역내에 저류지를 설치하여 첨두도달시간을 지연시키고 방류량은 하수관거의 통수능 이하로 조절하는 방안을 활용하고 있다. 저류지를 설계 운영함에 있어서 사용되는 수문모형은 일반적으로 계획모형, 설계모형 및 운영모형으로 분류되고 있다. 본 연구에서는 재해영향평가서 22개소의 기 설계된 저류지를 분석대상으로 하여 여러 가지 저류지 계획모형의 적합성을 검토하였다. 저류지 계획모형으로는 삼각형, 사다리꼴 설계수문곡선과 경험적 공식을 이용한 11가지의 모형을 적용하였다. 저류지 계획모형의 분석에서 on-line 저류지의 경우는 사다리꼴 형태 설계수문곡선을 채택하고 있는 이종태 등 모형(1991)의 결과가 대상 저류지의 실저류량과 가장 유사함을 보였고, off-line 저류지의 경우는 삼각형 형태 설계수문곡선을 채택하고 있는 Abt and Grigg 모형(1978)의 결과가 비교적 양호한 결과를 보이는 것으로 나타났다.

• 대한의용생체공학회:의공학회지
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• 제36권5호
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• pp.198-203
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• 2015

The purpose of the study is to examine the effects of pacemaker location on cardiac pumping efficacy theoretically. We used a three-dimensional finite element cardiac electromechanical model of canine ventricles with models of the circulatory system. Electrical activation time for normal sinus rhythm and artificial pacing in apex, left ventricular free wall, and right ventricular free wall were obtained from electrophysiological model. We applied the electrical activation time maps to the mechanical contraction model and obtained cardiac mechanical responses such as myocardial contractile ATP consumption, stroke work, stroke volume, ejection fraction, and etc. Among three artificial pacing methods, left ventricle pacing showed best performance in ventricular pumping efficacy.

• 설비공학논문집
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• 제7권3호
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• pp.396-405
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• 1995

Numerical calculations are carried out for the swirling turbulent flow in a pipe. Calculations are made for the flow with swirl parameter of 2.25 and the Reynolds number of 24,300. The turbulence closure models used in these calculations are two different types of Reynolds stress model, and the results are compared with those of $k-{\varepsilon}$ model and the experimental data. The finite volume method is used for the discretization, and the power-law scheme is employed as a numerical scheme. The SIMPLE algorithm is used for velocity-pressure correction. The computational results show that GL model gives the results better than those of SSG model in the predictions of velocity and stress components.

• Advances in environmental research
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• 제5권4호
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• pp.263-282
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• 2016

Contaminant transport in groundwater induces major threat and harmful effect on the environment; hence, the fate of the contaminant migration in groundwater is seeking a lot of attention. In this paper a two dimensional numerical flow and transport model through saturated layered soil is developed. Groundwater flow and solute transport has been simulated numerically using proposed model. The model implements the finite volume time splitting method to discretize the main equations. The performance, accuracy and efficiency of the out coming numerical models have been successfully examined by two test cases. The verification test cases consist of two-dimensional, groundwater flow and solute transport. The final purpose of this paper is to discuss and compare the shape of contaminant plume in homogeneous and heterogeneous media with different soil properties and control of solute transport using a zone for minimizing the potential of groundwater contamination; furthermore, this model leads to select the effective and optimum remedial strategies for cleaning the contaminated aquifers.

• 대한기계학회논문집
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• 제19권11호
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• pp.3014-3021
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• 1995

This study is carried out in order to evaluate the performances of the Reynolds stress turbulence models such as SSG and GL models in the calculation of separated flow over backward-facing stepp.In addition, two slow return-to-isotropy models, YA and Rotta models combined with rapid part of SSG model are also tested. The finite volume method is used to discretize the governing differential equations, and the power-law scheme is used to approximate the convection terms. The SIMPLE algorithm is used for pressure correction in the governing equations. The results show that SSG model gives the better prediction near the reattachment point than GL model. In cases that the rapid term of SSG model is combined with Rotta and YA slow models, the results show the better predictions of stress components in recirculation zone, but indicate inaccuracy in the predictions of mean velocity.

• Journal of the Korean Data and Information Science Society
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• 제22권6호
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• pp.1199-1215
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• 2011

Relaxing an unrealistic assumption of a representative percolation model, this paper demonstrates that herd behavior leads to a high increase in volatility but not trading volume, in contrast with information flows that give rise to increases in both volatility and trading volume. Although detecting herd behavior has posed a great challenge due to its empirical difficulty, this paper proposes a new methodology for detecting trading days with herding. Furthermore, this paper suggests a herd-behavior-stochastic-volatility model, which accounts for herding in financial markets. Strong evidence in favor of the model specification over the standard stochastic volatility model is based on empirical application with high frequency data in the Korean equity market, strongly supporting the intuition that herd behavior causes excess volatility. In addition, this research indicates that strong persistence in volatility, which is a prevalent feature in financial markets, is likely attributed to herd behavior rather than news.