• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.203-209
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• 2015

The purpose of this study is to estimate the applicability of a stable anaerobic digester using a separator membrane to the preprocessing thickening process. The results of the experiments showed about a 47.16% weight loss rate for the sludge under anaerobic condition, and about 41.17% under intermittent aeration condition. The concentrations of rejection water were $SCOD_{Cr}$ 25 mg/L, T-N 16.6 mg/L, and T-P 1.4 mg/L on the average under the intermittent aeration condition, which were lower than the concentrations of rejection water under an anaerobic condition. As for the factors affecting the reduction of the flux, correlation analyses of TTF, MLSS, $SCOD_{Cr}$, and $EPS_{Protein}$, $EPS_{Polysacchride}$ resulted in -0.97, -0.95, -0.84 and -0.86, -0.95, respectively, which showed that TTF had the highest correlation to the reduction of the flux. In addition, it was concluded that MLSS, $SCOD_{Cr}$ and $EPS_{Protein}$, $EPS_{Polysacchride}$ also have close correlations. The results are considered to show that, in the case of the process using a tubular membrane in the preprocessing process of an anaerobic digester, an intermittent aeration condition of the thickener considering the contamination of the membrane and load of rejection water is appropriate for the stable preprocessing process.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.590-597
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• 2009

The final quality of the workpiece is affected by the grinding process that has been conducted in final manufacturing stage. However the quality-satisfaction of ground workpiece depends on the skill of an expert in this process. Therefore, the process models of grinding have been developed to predict the states according to grinding process. In this paper, in order to find the optimized grinding condition to reduce the manufacturing expense and to meet requirements of ground workpiece optimization algorithm using E.S.(Evolutionary Strategy) is proposed. The proposed algorithm has been employed to find the optimal grinding and dressing condition using the grinding process models and nonlinear grinding constraints. The optimized results also presents the guide line of grinding process. The effectiveness of the proposed algorithm is verified through the experimental results.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1424-1425
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• 2006

A four-step rapid thermal annealing (RTA) process is proposed in order to improve the throughput and stabilize the process, compared to the six-step RTA process. Effects of annealing on the properties of a structure mode of CMOS process in both cases were investigated. The implanted dopant(As, $BF_2$ and Ti/TiN) movement in silicon during different rapid thermal annealing conditions was studied using secondary ion mass spectroscopy (SIMS) technique. These results show that the four-step RTA process significantly improves time effect and throughput (15%) by the condition of ramping up compared to the six-step RTA process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.4
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• pp.37-43
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• 2008

Working condition is one of the most important factors in precision working. In this study, we optimized the vibration acceleration level(VAL) of Al 2024 alloy to select optimum working condition of side wall end-milling using RSM(Response Surface Methodology). RSM was well adapted to make analytic model for minimizing vibration acceleration, created the objective function and saved a great deal of computational time. Therefore, it is expected that the proposed optimization procedure using RSM can be easily utilized to solve the optimization problem of working condition. The experimental results of the surface roughness and VAL showed the validity of the proposed working condition of side wall end-milling as it can be observed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.563-564
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• 2006

In silicon wafer manufacturing process, the grinding process has been adopted to improve the flatness of water. The grinding of wafer is usually used by the infeed grinding machine. Grinding conditions are spindle speed, feed speed, rotation speed, grinding stone etc. But grinding condition selection and analysis is so difficult in grinding machine. In the intelligent grinding system based on knowledge many researchers have studied expert system, neural network, fuzzy etc. In this paper we deal grinding condition selection method, Taguchi method and Genetic Analysis.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1215-1220
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• 2004

Reactive distillation (RD) is a combination process where both separation and reaction are considered simultaneously in a single vessel. This kind of combination to enhance the overall performance is not a new attempt in the chemical engineering areas. The recovery of ammonia in the classic Solvay process for soda ash of the 1860s may be cited as probably the first commercial application of RD. The RD system has been used for a long time as a useful process and recently the importance of the RD is enlarged more and more. In addition to that, the application fields of RD are diversely diverged. To make the most of the characteristic of RD system, we must decide the best operating condition under which the process shows the most effective productivity and should decide the best control algorithm which satisfies an optimal operating condition. Phosgene which is a highly reactive chemical is used for the production of isocyanates and polycarbonates. Because it has high reactivity and toxicity, its utilization is increasingly burdened by growing safety measures to be adopted during its production. Dimethyl Carbonate (DMC) was proposed as a substitute of phosgene because it is non-toxic and environmentally benign chemical. In this study, RD is used for DMC production process and the transesterification is performed inside of column to produce DMC. In transesterification, the methanol and ethylene carbonate (EC) are used as the reactants. This process use homogeneous catalyst and the azeotrope exists between the reactant and product. Owing to azeotrope, we should use two distillation columns. For this DMC production process, we can suggest two configurations. One is EC excess process and the other is methanol excess process. From the comparison of steady state simulation results where the Naphtali-Sandholm algorithm is used, it showed the better performance to use the methanol excess process configuration than EC excess process. Then, the dynamic simulation was performed to be based on the steady state simulation results and the optimal control system was designed. In addition to that, the optimal operating condition was suggested from previous results.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.9
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• pp.111-117
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• 2002

In most machining companies, operators decide the cutting condition, a pair of spindle speed (5) and table federate (F) by experience and subjective judgment. As cutting conditions are determined by operators' experience and ability, inconsistent cutting conditions are given in same operating conditions. The objective of this study is to develop the cutting condition decision system which utilizes shop data and predicts tool life by neural network and eventually leads to the optimal cutting condition. The production time per piece is considered for an optimization object. We will discuss the process of an optimal cutting condition decision by neural network. By this process, a series of shop data is stored. And neural network is constructed for prediction of tool life and the optimal cutting condition is recommended from a cutting condition decision system using the stored shop data. The results show that the developed system is rational in searching the optimal cutting conditions on job operations.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.231-238
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• 2016

In this study, we have investigated to find optimal pre-treatment flocculation condition by analyzing the floc growth rate with mixing conditions and the membrane permeation flux for pre-treatment step of the membrane process. The higher mixing intensity showed a constant floc size index (FSI) values, and lower mixing intensity increased the degree of dispersion of the FSI values. Results of comparing the distribution characteristics of the FSI value and the permeation flux were more effective in increasing flux when the FSI values were 0.2 or higher. The degree of dispersion of FSI was relatively large in 40 rpm mixing condition compared to 120 rpm. In 40 rpm mixing condition, it decreased the permeation flux compared to 120 rpm because various sizes of flocs were distributed. Coagulation-UF membrane process enhanced 30%~40% of the flux rate compare to UF alone process, and the coagulation-MF process increased up to 5% of the flux rate compare to MF alone process. Pre-treatment, that is, coagulation process, has been found to be less effects on relatively larger pore size for MF membrane. For UF membrane, the flux was a little bit same when applying only the rapid mixing process or rapid mixing with slow mixing processes together. In case of MF membrane, the flux was improved when rapid mixing process applied with slow mixing process together.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.1
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• pp.62-75
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• 2000

Most of biological treatment to remove contaminants in municipal wastewater have been conducted by activated sludge process. But, the process have several probIems such as enormous site needed for construction of treatment facilities, unstable treatment due to limited ability to control load fluctuation, frequent sludge bulking and appearance of lots of surplus sludge. In this study, the experiments were performed through submerging biofilm of PEPP media in existing aeration tank with raw water from municipal wastewater treatment plant and then submerging PVDC and PEPP media, different from shape and chemical peculiarity in anoxic reactor. Throughout the experience, nutrient removal efficiency according to HRT, nitrogen phosphorous removal efficiency, behavior of nitrogen and dewatering efficiency have been compared and analysed with those of activated sludge process. As the results, BOD removal efficiency according to BOD volumetric load and F/M ratio was not found any differency in two processes, but was decreased below 90% as going along the condition of high load in activated sludge process. Kinetic coefficient was $K_{max}=1.162day^{-1}$, $K_s=53.77mg/L$, $Y=0.166mgVSS/mgBOD_{rem}$. and $K_d=0.019day^{-1}$. It was found that the removal efficiency, even though in aerobic condition, in biofilm process equipped anoxic reactor was higher than the one in activated sludge process within the range of 70~80%, and became better as HRT increased. Phosphorous removal efficiency was not found any differency in two processes. In biofilm process, treament efficiency even in conditions of high load was not decreased, because the biomass concentration could be maintained in high condition compared with activated sludge process. As HRT increased, suspended and attached biomass was increased and the other hand, F/M ratio was decreased as biomass' increasing. Biomass thickness was increased. from $10.43{\mu}m$ to $10.55{\mu}m$ as HRT increased and density of biomass within $40.79{\sim}41.16mg/cm^2$. The results also present that the dewatering efficiency of sludge generated in biofilm process was higher than in activated sludge process, and became better as HRT increased.

• Journal of Korean Institute of Industrial Engineers
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• v.35 no.1
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• pp.40-50
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• 2009

Knowledge-based services are largely dependent upon human-driven works. Therefore, considering human characteristics is required when modeling processes for knowledge-based services. As an emerging technology for Business Process Management, Human Interaction Management and its supportive process management can be an alternative to deal with human-driven processes. However, current HIM does not suggest concrete method for modeling conditions that are essential to realize supportive process management. And the condition modeling of HumanEdj, the only HIM software implemented, reveals the problem of complexity. As a solution, this paper suggests a fact-oriented ontological approach to process modeling. The approach uses human-friendly form of facts for condition modeling.