• 산업경영시스템학회지
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• 제18권34호
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• pp.35-42
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• 1995

In the plastic extrusion process, product quality is influenced by work condition for temperature of cylinders and dies. The work conditions are various, so it is difficult to standardization of the work conditions. Therefore, the work conditions are depended on the workers of experience and skill. In the plastic extrusion process, it has five control heating points on the cylinder and three control heating points on the die. In addition, there is one control point on the extrusion process. It is extrusion speed. In this case, we don't know how these affect product quality. We structure the multiple linear regression equation with the temperature of cylinders and dies as independent variables and the product weight as dependent variable. We solve this equation using statistic computer package named Juse-Qcas.

• 소성∙가공
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• 제25권5호
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• pp.313-318
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• 2016

The plasma vapor coatings on two kinds of die steels have been carried out in order to identify the most optimized conditions. When TiN or TiAlN coatings were carried out on the substrates, the coating layer thicknesses were not significantly changed, and the optimized coating thickness was identified as ~ 5 μm. When the optimized coating conditions and stress analysis were applied to the primary piston dies for fabrication of aluminum cylinders, an extended life time of the die was observed. The methodology for extending the life time of dies was discussed in terms of microstructures and stress analysis.

• Journal of Welding and Joining
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• 제15권5호
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• pp.115-123
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• 1997

The buckling strength, fatigue strength, stress corrosion cracking are considerably effected on one of initial imperfections, the residual stresses produced by a circumferential weld between axisymmetric cylinders. Therefore, we study the residual stresses, plastic strain and temperature distribution with using thermal elasto-plastic analysis which are generated by a circumferential weld between axisymmetric cylinders. It is investigated that welding residual stresses have an effect on the strength of cylinder for inner and outer shell under external pressure.

• 대한기계학회논문집
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• 제18권5호
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• pp.1150-1157
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• 1994

This paper presents dynamic analysis of a hydraulic excavator based on experimental data. A three dimensional multibody model of a hydraulic excavator is modeled for the computer simulation. The hydraulic pressures acting on the cylinders are measured from experiments, and the forces exerting on the cylinders are calculated from the measured pressures. Using these forces, the dynamic analysis of the excavator is carried out to regenerate the motion in the computer simulation. A proper operation scheme is assumed to match the computational result and the experiment. The DADS program is used for the dynamic analysis.

• 드라이브 ㆍ 컨트롤
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• 제14권3호
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• pp.18-24
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• 2017

The purpose of this paper is to develop a new submersible fish cage operated by a pneumatic system for offshore aquaculture. Although some researchers have investigated modeling and control of fish cages, such cages consist of variable ballast tanks that with closed cylinders and thus present a maintenance issue. In solving the issue the new submersible fish cage investigated consists of bottom-opening cylinders. Accordingly, we designed a mathematical model of the concept and applied Sliding Mode Control for nonlinear angle control. Some experiments conducted under assumed conditions indicate that the angle of the system converges to zero under all conditions and the control has the stability to balance the fish cage.

• 한국전산유체공학회지
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• 제14권4호
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• pp.78-85
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• 2009

Cavitating flow simulation is of practical importance for many engineering systems, such as marine propellers, pump impellers, nozzles, injectors, torpedoes, etc. The present work has focused on the simulation of cavitating flow past cylinders with strong side flows. The governing equation is the Navier-Stokes equation based on the homogeneous mixture model. The momentum and energy equation is in the mixture phase while the continuity equation is solved liquid and vapor phase, separately. An implicit dual time and preconditioning method are employed for computational analysis. For the code validation, the results from the present solver have been compared with experiments and other numerical results. A fairly good agreement with the experimental data and other numerical results have been obtained. After the code validation, the strong side flow was applied to include the wake flow effects of the submarine or ocean tide.

• Structural Engineering and Mechanics
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• 제12권3호
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• pp.329-339
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• 2001

The present paper deals with the effective slenderness ratio of telescopic cylinders as a long column having different cross sections. Firstly, the slenderness ratio defined in the current standard for the telescopic cylinders is discussed to point out some difficulties which arise when the ratio is applied to the column having different cross sections. Secondly, a new effective slenderness ratio is proposed for columns having different cross sections by introducing a partial effective slenderness ratio. Finally, the proposed slenderness ratio is applied, for extending and development of discussion, to a two-staged column having piece-wise constant cross sections and a cylindrical column having linearly varying diameters.

• Structural Engineering and Mechanics
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• 제24권6호
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• pp.699-707
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• 2006

In the paper, a direct method of solution of the Navier equation is presented. An orthotropic thick hollow cylinder under a one-dimensional steady-state temperature distribution and a uniform magnetic field with general types of thermal and mechanical boundary conditions is considered. The Navier equation in terms of displacement is derived and solved analytically by the direct method, and magnetothermoelastic responses and perturbation of the magnetic field vector in the orthotropic thick hollow cylinder is described. The present method is suitable for orthotropic thick hollow cylinders placed in an axial magnetic field with arbitrary thermal and mechanical boundary conditions. Finally, numerical examples are carried out and discussed.

• Journal of Advanced Marine Engineering and Technology
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• 제23권2호
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• pp.131-139
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• 1999

An experimental study was conducted to investigate the fouling effects of geothermal water scale deposited onto a heating surface upon its forced convection heat transfer characteristics. Scales deposited onto the heating surfaces of heat exchangers seriously reduce the heat transfer perfor-mance and also increase the hydrodynamic drag. Accordingly fouling is an important problem in the design and operation of heat exchangers. The cylinders were settled in tandem with equal dis-tance between neighbouring cylinders and only the test cylinder was heated under the condition of constant heat flux. The Reynolds number was varied from 13000310 through 50003100. It is found that the heat transfer of the in-line tube banks greatly varies with the fouling of geothermal water scale especially its scale height. Further the local and average Nusselt numbers strongly depend upon the cylinder spacing and the Reynolds number.

• 대한기계학회논문집B
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• 제28권11호
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• pp.1449-1458
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• 2004

The influence of eccentric(=staggeredness) ratio between stationary upstream circular cylinders on heat transfer characteristics of a heated downstream circular cylinder installed in a channel was investigated experimentally. In order to enhance the heat transfer rate of the heated downstream cylinder surface, we have changed the configuration of upstream cylinder. As a result, we were able to obtain local time-averaged convective heat transfer enhancement of the heated cylinder by the relative replacement of upstream cylinder. This is basically attributed to the mean flow structure change, such as flow separation, vortex shedding, and recirculation of the upstream cylinder including the reattachment and new thermal boundary developed at the downstream cylinder which are the results of the increase of the staggeredness ratio.