• Food Science and Biotechnology
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• 제14권3호
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• pp.413-415
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• 2005

Time-dependent flow properties of commercial kochujang (hot pepper-soybean paste) were evaluated at various shear rates (5, 15, 25, and $35\;sec^{-1}$) and temperatures (5, 15, and $25^{\circ}C$). Flow properties of all samples showed thixotropic behaviors, which were qualitatively evaluated and quantitatively described by the Weltman, Hahn, and Figoni and Shoemaker models. Time-dependent flow properties of kochujang were found to vary over the range of the shear rate and temperature investigated. Time-dependent models of Weltman and Hahn were suitable ($R^2=0.923-0.987$) for commercial kochujang.

• Management Science and Financial Engineering
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• 제4권2호
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• pp.1-13
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• 1998

The Shortest Path Problem in Time-dependent Networks, where the travel time of each link depends on the time interval, is not realistic since the model and its solution violate the Non-passing Property (NPP:often referred to as FIFO) of real phenomena. Furthermore, solving the problem needs much more computational and memory complexity than the general shortest path problem. A new model for Time-dependent Networks where the flow speeds of each link depend on time interval, is suggested. The model is more realistic since its solution maintains the NPP. Solving the problem needs just a little more computational complexity, and the same memory complexity, as the general shortest path problem. A solution algorithm modified from Dijkstra's label setting algorithm is presented. We extend this model to the problem of Minimum Expected Time Path in Time-dependent Stochastic Networks where flow speeds of each link change statistically on each time interval. A solution method using the Kth-shortest Path algorithm is presented.

• 한국해양공학회지
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• 제14권3호
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• pp.35-40
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• 2000

SMAC method is, one of the numerical simulation techniques, modified from the original MAC for the time-dependent variation of fluid flows. The Navier-Stokes equation for incompressible time-dependent viscous flow is applied and, also marker particles which move with the fluid are used. Two-dimensional numerical computations of fluid flow are carried out in a virtual water tank. This paper has shown very well the movements of marker particles using SMAC method.

• Journal of applied mathematics & informatics
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• 제18권1_2호
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• pp.383-391
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• 2005

The paper is devoted to some flow shop scheduling problems, where job processing times are defined by functions dependent on their positions in the schedule. An example is constructed to show that the classical Johnson's rule is not the optimal solution for two different models of the two-machine flow shop scheduling to minimize makespan. In order to solve the makespan minimization problem in the two-machine flow shop scheduling, we suggest Johnson's rule as a heuristic algorithm, for which the worst-case bound is calculated. We find polynomial time solutions to some special cases of the considered problems for the following optimization criteria: the weighted sum of completion times and maximum lateness. Some furthermore extensions of the problems are also shown.

• Geomechanics and Engineering
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• 제37권2호
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• pp.179-187
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• 2024

In this paper, a unified time-dependent constitutive model of Darcy flow and non-Darcy flow is proposed. The influencing factors of flow velocity are discussed, which demonstrates that permeability coefficient is the most significant factor. Based on this, the dynamic evolution characteristics of water inrush during tunneling through fault fracture zone is analyzed under the constant permeability coefficient condition (CPCC). It indicates that the curves of flow velocity and hydrostatic pressure can be divided into typical three stages: approximate high-velocity zone inside the fault fracture zone, velocity-rising zone near the tunnel excavation face and attenuation-low velocity zone in the tunnel. Furthermore, given the variation of permeability coefficient of the fault fracture zone with depth and time, the dynamic evolution of water flow in the fault fracture zone under the variable permeability coefficient condition (VPCC) is also studied. The results show that the time-related factor (α) affects the dynamic evolution distribution of flow velocity with time, the depth-related factor (A) is the key factor to the dynamic evolution of hydrostatic pressure.

• 한국식품과학회지
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• 제35권1호
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• pp.155-158
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• 2003

겨자 페이스트의 시간의존성을 관찰하기 위해 총고형분 함량(18, 21, 24, 27, 30%)과 전단속도$(15,\;20,\;25\;s^{-1})$를 달리하여 시간-전단응력 변화가 분석되었으며, 이들 데이터들은 Figoni 및 Shoemaker 모델, Weltman 모델, Hahn 모델에 적용하여 정량적으로 평가되었다. 일정한 전단속도에서 겨자페이스트의 농도가 증가함에 따라 보다 높은 전단응력을 나타냈으며, 3종류의 모델식에서의 각 매개변수들은 농도에 따라 일정한 경향을 나타내어 겨자 페이스트의 시간의존 유동 특성에는 다른 분산식품들과 마찬가지로 농도에 의해 크게 영향을 받음을 알 수 있었다. 그러나 일정 농도를 기준으로 전단속도에 따른 시간의존성 변화에서는 25%와 27%농도를 가진 시료를 제외하고는 각 매개변수 값들의 차이는 거의 없는 것으로 나타났다. 시간의존 유동특성 모델에 적용한 결과, Weltman 모델이 다른 모델식에 비해 가장 높은 결정계수$(R^2)$을 보여주고 있어 Weltman 모델식이 겨자 페이스트 시간의존성을 나타내는 가장 적합한 모델식임을 알 수 있었다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.1636-1640
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• 2006

SMAC method, one of the computational fluid dynamics techniques, is modified from the original MAC method for the time-dependent variation of flow analysis. The Navier-Stokes equations for incompressible time-dependent viscous flow are applied, and also marker particles that present the visualization of flow analysis are used. In this study SMAC technique is used to analyze the flow behavior in the water-filling of virtual channel. Then by changes of diameter of two ingates, the change of velocity and discharge when two ingates are filled the water to virtual channel are simulated. As a result, water-filling flow pattern in the virtual channel is simulated very well. Therefore, this numerical simulation will also be applied for the design of structures as open flume and porous breakwater.

• 대한화학회지
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• 제48권6호
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• pp.663-666
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• 2004

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3009-3014
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• 2007

The effectiveness of passive control techniques for alleviating the pressure oscillation generated in a supersonic cavity flow was investigated numerically and experimentally, respectively. The control device includes a sub-cavity installed near the leading edge of a rectangular cavity. Time-dependent supersonic cavity flow characteristics with turbulent features were examined by using the three-dimensional, mass-averaged Navier-Stokes computation based on a finite volume scheme and large eddy simulation. The results show that the pressure oscillation near the trailing edge dominates overall time-dependent cavity pressure variations. Such an oscillation can be attenuated more significantly in the presence of the sub-cavity compared with the cavity without sub-cavity, and a larger sub-cavity leads to better control performance.

• 한국안전학회지
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• 제22권2호
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• pp.1-7
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• 2007

A problem of a unsteady time-dependent flow in a channel is of practical importance and widely considered in the design of devices such as heat exchangers, duct, and electronic equipments. The characteristics of fluid flow in channel with oscillating vortex generator was investigated experimentally. The main object of this study was to investigate the effect of the excited frequency, the excited amplitude, and Reynolds numbers on the generated frequency. Flow patterns were visualized using smoke generator and generated frequencies were measured using hot wire anemometer. When the excited frequency is increased, excited amplitude decreased and Reynolds number increased, the strength of PSD of generated frequency is decreased.