• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.639-642
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• 1990

본 EXOTHERMIC BATCH 공정은 두 개의 FLUID BED REACTOR로 구성되며 여기서 다종의 제품이 생산된다. 각 제품은 그 제품 자체의 특징 온도 패턴을 갖게 되며 허용한계를 벗어나지 않는 제품을 생산하기 위해서는 그 특징 온도 패턴대로 제어되어야 하며 실패할 경우 그 배치를 포기하여야만 한다. 초기의 배치제어시스템에서는 램프 제너레이터(RAMP GENERATOR) 기능이 있는 공기식 계기가 사용되었으며 제품을 변경하기 위해서는 각 제품마다 일일이 그 특징 패턴을 수동으로 입력시켜 주어야만 했다. 이 과정에서 한 개의 파라미터를 실수하면 사용할 수 없는 제품이 된다. 다종 제품의 화학공정에서는 품질과 생산량 향상에 의한 이득 증대에 그 목표를 두고 있으며, 이와 같은 목표를 달성하기 위한 해결책은 운전자의 개입을 감소시켜주는 제어시스템으로 개선하는 것이었다. 본 논문에서는 배치공정에 있어서의 프로그래머블 콘트롤러(PROGRAMMABLE CONTROLLER)의 응용에 관하여 논술하고자 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.2
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• pp.175-182
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• 2007

The objective of the present study is to investigate the heat storage characteristics of a packed bed according to periodically oscillating flows. Experiments have been performed to measure transient temperature distributions in solid and fluid Phases of the porous media. A simplified analytical model has been developed with intra-particle and dispersion effects neglected, and non-dimensional parameters have been derived. The transient temperature distributions according to the simplified numerical model agree well with the experimental results. Heat storage efficiencies defined in two different ways are obtained for various time periods and face velocities.

• Water Engineering Research
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• v.3 no.3
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• pp.177-193
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• 2002

Experiments were conducted in an initially straight laboratory alluvial channel to investigate channel meandering characteristics. The experimental observations revealed an empirical relation between three types of tortuosity ratios used for describing meandering characteristics. Furthermore, the Strauhal number was found to be higher for bed material with greater resistance to erosion than with lower resistance to erosion. The meandering characteristics were also investigated using the concept of buckling employed in solid mechanics and the concept of siphoning of fluid mechanics. The buckling of flow, attributable to the flow nonuniformity across the channel cross-section, was found to follow the same pattern as did meandering observed experimentally. The processes of expansion of meanders and cut-off can be explained using the concept of siphoning. The results of expanding meander planforms observed in four experimental tests supported the viability of these concepts.

• The Korean Journal of Pain
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• v.18 no.1
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• pp.60-63
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• 2005

This report describes the successful treatment of spontaneous intracranial hypotension (SIH) with multiple cerebrospinal fluid (CSF) leaks using 10 applications of epidural blood patches (EBP). A forty year old female who suffered with a postural headache was diagnosed as having SIH. On the cisternography, multiple CSF leaks were noted at the thoracic and lumbar area. Her headache was not improved with conservative treatments such as bed rest, hydration and NSAIDS. So, she underwent treatment with EBPs. After 10 applications of site-directed EBPs, her headache was resolved gradually and completely without any complications.

• Journal of Drive and Control
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• v.19 no.4
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• pp.70-76
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• 2022

In this paper, we develops an unmanned test system for the purpose of realizing an actual forklift-based test-bed for the operation durability of the forklift mast. First, two robot actuators were applied to the lever to replace lever manipulation of the operator. For detecting the height of the fork and the tilt angle of the mast, the laser displacement sensor and the inclinometer were installed to the forklift. Next, the embedded control system was used to control the robot actuator with reference to test mode. Experimental evaluation verified that developed test system was effective and practical for the viewpoint of the repeatability of the test mode.

• Structural Engineering and Mechanics
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• v.78 no.4
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• pp.497-518
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• 2021

In this study, a new method for treating the wall boundary in smoothed particle hydrodynamics (SPH) is proposed to simulate free surface flows effectively. Unlike conventional methods of wall boundary treatment through boundary particles, in the proposed method, the wall boundary condition is directly imposed by adding boundary truncation terms to the mass and momentum conservation equations. Thus, boundary particles are not used in boundary modeling. Doing so, the wall boundary condition is accurately imposed, boundary modeling is simplified, and computation is made efficient without losing stability in SPH. Performance of the proposed method is demonstrated through several numerical examples: dam break, dam break with a wedge, sloshing, inclined bed, cross-lever rotation, pulsating tank and sloshing with a flexible baffle. These results are compared with available experimental results, analytical solutions, and results obtained using the boundary particle method.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.931-937
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• 2008

Rigorous multiscale modelling and simulation of the MTR for WGSR was carried out to accurately predict the behavior of process variables and the reactor performance. The MTR consists of 4 fixed bed tube reactors packed with heterogeneous catalysts, as well as surrounding shell part for the cooling purpose. Considering that fluid flow field and reaction kinetics give a great influence on the reactor performance, employing multiscale methodology encompassing Computational Fluid Dynamics (CFD) and process modeling was natural and, in a sense, inevitable conclusion. Inlet and outlet temperature of the reactant fluid at the tube side was $345^{\circ}C$ and $390^{\circ}C$, respectively and the CO conversion at the exit of the tube side with these conditions approached to about 0.89. At the shell side, the inlet and outlet temperature of the cooling fluid, which flows counter-currently to tube flow, was $190^{\circ}C$ and $240^{\circ}C$. From this heat exchange, the energy saving was achieved for the flow at shell side and temperature of the tube side was properly controlled to obtain high CO conversion. The simulation results from this research were accurately comparable to the experimental data from various papers.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1172-1182
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• 2002

In the present study a general criterion for local thermal equilibrium is presented in terms of parameters of engineering importance which include the Darcy number, the effective Prandtl number of fluid, and the Reynolds number. For this, an order of magnitude analysis is performed for the case when the effect of convection heat transfer is dominant in a porous structure. The criterion proposed in this study is more general than the previous criterion suggested by Carbonell and Whitaker, because the latter is applicable only when conduction is the dominant heat transfer mode in a porous medium while the former can be applied even when convection heat transfer prevails. In order to check the validity of the proposed criterion for local thermal equilibrium, the forced convection phenomena in a porous medium with a microchanneled structure subject to an impinging jet are studied using a similarity transformation. The proposed criterion is also validated with the existing experimental and numerical results for convection heat transfer in various porous materials that include some of the parameters used in the criterion such as a microchannel heat sink with a parallel flow, a packed bed, a cellular ceramic, and a sintered metal. It is shown that the criterion presented in this work well-predicts the validity of the assumption of local thermal equilibrium in a porous medium.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.229-234
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• 2005

Following the recent trend in the automotive manufacturing technologies, the product design subject to the die casting becomes more and more complex. The requirement of the die design becomes more demanding than ever before. In some cases the product's shape can have multiple slender manifolds. In such cases, design of the inlet and outlet parts of the die is very important in the whole manufacturing process. The main issues required for the qualified products are to attain gentle and uniform flow of the molten liquid within the passages of the die. To satisfy such issues, the inlet cylinder ('bed cylinder' in this paper) must be as large as possible and simultaneously the outlet opening at the end of each passage must be as small as possible. However these in turn obviously bring additional manufacturing costs caused by re-melting of the bed cylinder and increased power due to the small outlet-openings. The purpose of this paper is to develop effective simulation methods of calculation for fluid flows in multiple columns, which mimic the actual complex design, and to get some useful information which can give some contributions to the die-casting industry. We have used a commercial code CFX in the numerical simulation. The primary parameter involved is the size of the air-vent. We will show how the very small opening of the outlet, i.e. the air-vent, can be treated with the aid of the porous model provided in the code. To check the validity of the numerical results we have also conducted a simple experiment by using water.

• Journal of Pharmaceutical Investigation
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• v.37 no.2
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• pp.101-106
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• 2007

Venlafaxine, 1-[2-(dimethylamino)-1-(4-methoxyphenyl)ethyl] cyclohexanol hydrochloride is a novel, nontricyclic antidepressant. venlafaxine is a unique antidepressant that differs structurally from other currently available. The aim ot the study was to formulate sustained-release venlafaxine granules and assess their formulation variables. It consists of two layers, venlafaxine drug layer and sustained release coating layer and manufactured by fluidized bed process. The sustained release of drug could be increased by double-control rising various components in venlafaxine drug layer and sustained-release layer. The drug-containing granules were coated with cellulose acetate, cetyl alcohol and Eudragit RS along with plastisizer such as dibuthyl sebacate as an nano-pore former The release oi venlafaxine depended on the type of Eudragit such as RS, and RL used in the formulation of controlled release layer. These results obtained clearly suggest that the sustained release oral delivery system for venlafaxine could be designed with satisfying drug release profile approved.