• Korean Chemical Engineering Research
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• 제54권5호
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• pp.606-611
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• 2016

Carbon dioxide injection is a widely known method of enhanced oil recovery (EOR). It is critical for the $CO_2$ EOR that the injected $CO_2$ to reach a condition fully miscible with oil. To reach the miscible point, a certain level of pressure is required, which is known as minimum miscibility pressure (MMP). In this study, a MMP prediction method using a process simulator is proposed. To validate the results of the simulation, those are compared to a slim tube experiment and several empirical correlations of previous literatures. Aspen HYSYS is utilized as the process simulator to create a model of $CO_2$/crude oil encounter. The results of the study show that the process simulator model is capable of predicting MMP and comparable to other published methods.

• Membrane and Water Treatment
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• 제9권5호
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• pp.335-342
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• 2018

Micelle-Enhanced Ultrafiltration (MEUF) is a membrane separation processes that improving ultrafiltration process with the formation of micelles of the surface active agents. Surface active agents are widely used to improve membrane processes due to the ability to trap organic compounds and metals in the treatment of industrial waste water. In this study, surface active agents are used to improve micelle-enhanced ultrafiltration (MEUF) to reduce chemical oxygen demand (COD), total dissolved solid (TDS), turbidity and clogging the membrane in dairy wastewater treatment. Three important operational factors (anionic surface active agent concentration, pressure and pH) and these interactions were investigated by using response surface methodology (RSM) and Box-Behnken design. Results show that due to the concentration polarization layer and increase the number of Micelles; the anionic surface active agent concentration has a negative effect on the flux and has a positive effect on the elimination of contamination indices. pH, and the pressure have the greatest effect on flux. On the other hand, it could be stated that these percentages of separation are in the percentages range of Nano-filtration (NF). While MEUF process has higher flux than NF process. The results have been achieved at lower pressure while NF process needs high pressure, thus making MEUF is the replacement for the NF process.

• 소성∙가공
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• 제28권6호
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• pp.347-353
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• 2019

The porthole extrusion process is a classic metal forming process to produce complex cross-section shaped aluminum profile. It is very difficult to design porthole die and extrusion process because of the complex shape of extrusion die and internal metal flow. The main variables in this process are ram speed, initial billet and tool temperature, and die shape. In general, the metal flow of porthole extrusion process can be divided into two steps. During the first step, the billet is divided into several parts in the porthole die bridge. During the second step, the divided billets are welded in the welding chamber. In the welding chamber, the level of welding pressure is very important for the quality of the final product. The purpose of this study is to increase the welding pressure in the welding chamber by using a two stage welding chamber. The porthole extrusion die was designed by using the Taguchi method with orthogonal array. The effectiveness of the optimized porthole die was verified by using the finite element analysis.

• 한국생산제조학회지
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• 제21권2호
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• pp.331-336
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• 2012

This study was aimed at the design of the dies for the guide valve for the fuel pressure regulator using the computer simulation to shorten the period of production, on the basis of the process planning which was designed by the field experts. In the computer simulation, 'Deform-3d' and 'Eesy-DieOpt' have been used, which are the commercial process analysis and die design program. Through the process analysis, we could know the propriety of the forming process, the inner pressure of the die and the suitable fitting pressure between the insert and the sleeve which was not showing any positive tangential stresses in the insert. Through the simulation of die design, we could know the number of the stress ring, the diameter ratios, the stresses of the die, the shrink fitting tolerance and temperature in the condition of the already determined maximum outer die diameter of the multi-stage former. The validity of the die design using the computer simulation was analyzed by the experiments and the results were satisfactory. As the results of this study, the new and easy die design system for multi-forging has been developed.

• 소성∙가공
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• 제18권8호
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• pp.607-616
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• 2009

There are three sub-processes associated with the assembly of the valve seat and cylinder head; heat fitting, cold fitting, and shrink fitting. In the heat fitting stage, the cylinder head is heated to a specified temperature and then squeezed toward the outer diameter of the valve seat. The cold fitting process cools the valve seat and safely squeezes it toward the inner diameter of cylinder head. However, these methods increased the installations & running cost and curtailed productivity. To address these problems, we analyzed the shrink fitting process using the contact pressure caused by fitting interference between the outer diameter of the valve seat and the inner diameter of the cylinder head. In this study, a closed form equation for predicting the contact pressure and fitting load is proposed. For quality control of the assembly line, principal factors of the shrink fitting process influenced in contact pressure were simulated by the FEM. Actual loads measured in the field showed good agreement with the results obtained by theoretical and finite element analysis.

• 한국전기전자재료학회논문지
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• 제13권10호
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• pp.812-816
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• 2000

It is very important to understand the correlation of between inter dielectric(ILD) CMP process and various facility factors supplied to equipment to equipment system. In this paper, the correlation between the various facility factors supplied to CMP equipment system and ILD-CMP process was studied. To prevent the partial over-polishing(edge hot-spot) generated in the wafer edge area during polishing, we analyze various facilities supplied at supply system. With facility shortage of D.I water(DIW) pressure, we introduced an adding purified $N_2$(P$N_2$)gas in polishing head cleaning station for increasing a cleaning effect. DIW pressure and P$N_2$gas factors were not related with removal rate, but edge hot-spot of patterned wafer had a serious relation. We estimated two factors (DIW pressure and P$N_2$gas) for the improvement of CMP process. Especially, we obtained a uniform planarity in patterned wafer and prohibited more than 90% wafer edge over-polishing. In this study, we acknowledged that facility factors supplied to equipment system played an important role in ILD-CMP process.

• 한국수소및신에너지학회논문집
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• 제32권4호
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• pp.197-204
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• 2021

Pressure swing adsorption is a purification process which can get pure hydrogen. The purification process is composed of four process: compression, adsorption, desorption and discharge. In this study the adsorption process was simulated by using the Fluent and validated with experimental results. A gas used in experiment is composed of H₂, CO₂, CH₄, and CO. Adsorption process conducted under 313 kelvin and 3 bar and bituminous-coal-based (BPL) activated carbon was used as the adsorbent. Langmuir model was applied to explain the gas adsorption. And diffusion of all the gases was controlled by micro-pore resistances. The result shows that, the most adsorbed gas was carbon dioxide, followed by methane and carbon monoxide. And carbon monoxide took the least amount of time to reach the maximum adsorption amount. The molar fraction of the off-gas became the same as the molar fraction of the gas supplied from the inlet after adsorption reached the equilibrium.

• 한국분말재료학회지
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• 제22권1호
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• pp.6-9
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• 2015

In this study, the behavior of densification of copper powders during high-pressure torsion (HPT) at room temperature is investigated using the finite element method. The simulation results show that the center of the workpiece is the first to reach the true density of copper during the compressive stage because the pressure is higher at the center than the periphery. Subsequently, whole workpiece reaches true density after compression due to the high pressure. In addition, the effective strain is increased along the radius during torsional stage. After one rotation, the periphery shows that the effective strain is increased up to 25, which is extensive deformation. These high pressure and severe strain do not only play a key role in consolidation of copper powders but also make the matrix harder by grain refinement.

• International Journal of Air-Conditioning and Refrigeration
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• 제14권1호
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• pp.19-27
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• 2006

The characteristics of heat transfer and pressure drop have been investigated experimentally during gas-cooling process of carbon dioxide. The results of this study are useful information in the design of a heat exchanger of $CO_2$ refrigerator. The test section consists of 6 series of copper tube, 4.15 and 2.18mm ID, respectively. The inlet temperature, the operating pressure, and the mass flux are varied in the range of $80{\sim}120^{\circ}C,\;{7\sim}10MPa,\;and\;400{\sim}1,900kg/m^2s$, respectively. The heat transfer coefficient of $CO_2$ is affected by temperature, inlet pressure, and mass flux of $CO_2$. At the maximum HTC, the temperature of $CO_2$ nearly accords with the psuedocritical temperature. It is found that the pressure drop is substantially affected by mass flux and inlet pressure of $CO_2$ . The results have been compared with those of previous work. The heat transfer correlation at the gas-cooling process has been also suggested which predicts within the error of 20%.

• 한국정밀공학회지
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• 제20권1호
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• pp.205-213
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• 2003

The fiber reinforced composite material is widely used in the multi-industrial field where the weight reduction of the infrastructure is demanded because of their high specific modulus and specific strength. It has two main merits which are to cut down energy by reducing weight and to prevent explosive damage preceding to the sudden bursting which is generated by the pressure leakage condition. Therefore, Pressure vessels using this composite material in comparison with conventional metal vessels can be applied in the field such as defense industry, aerospace industry and rocket motor case where lightweight and the high pressure are demanded. In this paper, for nonlinear finite element analysis of E-glass/epoxy filament winding composite pressure vessel receiving an internal pressure, the standard interpretation model is developed by using the ANSYS, general commercial software, which is verified as the accuracy and useful characteristic of the solution based on Auto LISP and ANSYS APDL. Both the preprocessor for doing exclusive analysis of filament winding composite pressure vessel and postprocessor that simplifies result of analysis have been developed to help the design engineers.