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여영구 한국시뮬레이션학회 1994 한국시뮬레이션학회 논문지 Vol.3 No.1
For the identification of the optimal operating conditions of phosphoric acid plant, an intelligent simulation was performed based on the dissolution reaction of phosphate rock. A phosphoric acid plant consists of three main processes : ball-mill grinding process, rock reaction process and slurry filteration process. The grinding and filteration processes are relatively simple processes and most of the simulation works are on the reaction process. The practical operation data of phosphoric acid plant at Namhae Chemical Corp. were utilized in the simulation. The operation of the phosphoric acid plant is highly dependent on the heuristics of operators and so the expert system technology was employed. The operation of phosphoric acid plant varies with the origin of phosphate rock. Results of the simulation showed the optimal values of major process variables and optimal operating conditions. The knowledgebase for the expert system was constructed based on the interview with the experienced plant operators.
Kinetics of volume expansion during infusion of Ringer’s solution based on single volume model
여영구,최규택 한국화학공학회 2006 Korean Journal of Chemical Engineering Vol.23 No.4
this work the kinetics of volume changes of fluid spaces asociated with infusion of Ringer’s solutionare analyzed by using the single-fluid space model. During infusion of Ringer’s solution, the human body is assumedto be characterized by the single-fluid space model into which fluid is fed and from which fluid leaves. Various infusiontypes were tested to accommodate different medical situations. Volunteers were given Ringer’s solution and the changesfound to represent adequately the kinetics of human volume expansion during infusion of Ringer’s solution.
Control of pH Processes Based on the Genetic Algorithm
여영구,Tae-In Kwon 한국화학공학회 2004 Korean Journal of Chemical Engineering Vol.21 No.1
In this work, we propose a PID control strategy based on the genetic algorithm coupled with cubic spline interpolation method for the control of pH processes. The control scheme proposed in the present work consists of closed-loop identification based on the genetic algorithm and cubic spline method. First, we compute the parameters (KC, , tD) of the PID controller using relay feedback and apply these parameters to control the pH Process. Then approximate linear models corresponding to each pH range are obtained by the closed-loop identification based on closed-loop operation data. The optimal parameters of the PID controller at each pH region are then computed by using the genetic algorithm. From numerical simulations and control experiments we could achieve better control performance compared to the conventional fixed gain PID control method.
Modeling and Simulation of Wet-end White Water System in the Paper Mill
여영구,이성철,Jae Yong Ryu,Hong Kang 한국화학공학회 2004 Korean Journal of Chemical Engineering Vol.21 No.2
A dynamic model representing the wet-end of a paper mill is developed to characterize its dynamic behavior. The model is based on the mass balance relationships written for the simplified wet-end white water network. The dynamic response of the wet-end is influenced both by the white water volume and by the level of wire retention. Effects of key manipulated variables such as the thick stock flow rate, the ash flow rate and the retention aid rate on the major controlled variables are analyzed by numerical simulations. It can be said that the consistency of the model with plant data seems to be reasonably good and can be used as a tool for plant analysis and control.
Analysis of the Wet-end Dynamics in Paper Mills
여영구,이성철,DongJunSeo,HongKang,JaeYongRyu 한국펄프.종이工學會 2003 펄프.종이기술 Vol.35 No.5
For the purpose of manufacturing water-resistant corrugated board boxes for agricultural products in the cold chain system, the effects of fiber types, wet strength agents and a moisture-proof chemical on the properties of the base papers were investigated first. PAE(polyamide amine epichlorohydrin) showed better performance than MF(melamine formalde-hyde) over broad stock pH ranges, which was prefered as wet strength agent for the paper grade. When short fibers(AOCC, KOCC) were mixed with long fiber(UKP) in certain ratios, some physical properties of the paper made with mixed fibers were similar to those of the paper made with UKP only. Paper containing AOCC showed the biggest increase in water resistance when PAE was added to the stock. Synergistic effects in moisture-proof and some mechanical properties of paper were appeared when PAR was added internally, together with the coating of a moisture proof chemical on the sheets.
여영구,나병기,송형근,이화웅,김유창,정연수 한국화학공학회 1998 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.36 No.4
연소가스로부터 CO₂를 회수하기 위한 Pressure Swing Adsorption(PSA) 공정의 전산모사를 통해 감압단계, 진공단계, 압력균등화단계 및 세정단계 등이 포함된 여러 공정의 성능을 비교, 분석함으로써 최적의 공정을 찾고자 하였다. 본 연구에서는 PSA 공정의 동특성이 고려되었으며 흡착제로는 활성탄이 이용되었다. 압력균등화단계의 도입은 감압단계에서 손실되는 생성물의 양을 줄이고 탑내에 존재하는 여러 성분들을 제분배하여 회수율과 순도를 증가시켰으며 세정단계의 도입을 통해 진공단계에서 얻어진 고동도의 CO₂를 환류시킴으로써 순도를 증가시킬 수 있었다. 특히 압력균등화단계와 세정단계를 결합하여 공정을 구성하였을 때 압력균등화단계는 분리능력의 증가와 함께 탑내의 N₂농도를 최소화시켜 성능을 향상시키는데 중요한 역할을 한다는 사실을 확인하였으며 CO₂의 회수율이 55%일 때 최고 순도는 97%를 얻을 수 있었다. The simulation of pressure swing adsorption(PSA) process for recovering highly pure CO₂ from flue gas was performed. Seven different processes including blowdown, pressure equalization, rinse and/or evacuation step were compared to obtain optimal process. In this study, bed dynamics was considered for the better simulated result. Activated carbon was used as an adsorbent. Pressure equalization contributed to increase the recovery and purity by preventing CO₂ loss at blowdown and redistributing the components in the bed. And also, rinse, recycling the product gas recovered at evacuation step, conduced in increase the purity by readsorbing highly concentrated CO₂. Especially, pressure equalization step combined with rinse step plays a key role in improving the, performance of process because of minimizing the concentration of N₂ in bed and increasing pressure difference between the bed pressure and atmospheric pressure. Maximum purity was about 97% and recovery at that point was about 55%.