• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.306-313
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• 2011

Lactic acid is widely used in the food, chemical and pharmaceutical industries, and there is an increasing demand for lactic acid as the raw material of polylactic acid, which is a biodegradable polymer. The presence of high boilers and non volatility of lactic acid makes the separation of lactic acid very difficult job. Esterification of lactic acid with methanol followed by hydrolysis of the separated methyl lactate was employed for the recovery of lactic acid. Reactive dividing wall column was proposed for the simultaneous reaction and separation. The intensified process poses a challenging control problem. Dynamic characteristics of the proposed process were examined and control systems were proposed to get a stable control performance for a disturbance in feed. Control performances of the proposed control systems were compared.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.3
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• pp.196-200
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• 2000

A neural controller for process control is proposed that combines a conventional multi-loop PID controller with a neural network. The concept of target signal based on feedback error is used fur on-line learning of the neural network. This controller is applied to distillation column control to illustrate its effectiveness. The result shows that the proposed neural controller can cope well with disturbance, strong interactions, time delays without any prior knowledge of the process.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.2
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• pp.136-139
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• 2000

A neural controller for process control is proposed that combines a conventional multi-loop PID controller with a neural network. The concept of target signal based on feedback error is used for on-line learning of the neural network. This controller is applied to distillation column control to illustrate its effectiveness. The result shows that the proposed neural controller can cope well with disturbance, strong interactions, time delays without any prior knowledge of the process.

• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.166-168
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• 1993

• International Journal of Control, Automation, and Systems
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• v.3 no.2
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• pp.252-257
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• 2005

In this work, we propose a simple but efficient method to design a target temperature trajectory for pulling speed tracking control of the crystal grower in the Czochralski crystallization process. In the suggested method, the model predictive control strategy is used to incorporate the complex dynamic effect of the heater temperature on the pulling speed into the temperature trajectory design quantitatively. The feedforward trajectories designed by the proposed method were implemented on 200 mm and 300 mm silicon crystal growers in the commercial Czochralski process. The application results have demonstrated its excellent and consistent tracking performance of pulling speed along whole bulk crystal growth.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.263-266
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• 1996

A method to determine an optimal temperature trajectory that guarantees polymer products having controlled molecular weight distribution and desired values of molecular weight is presented. The coordinate transformation method and the optimal control theory are applied to a batch PMMA polymerization system to calculate the optimal temperature trajectory. Coordinate transformation method converts the original fixed-end-point, free-end-time problem to a free-end-point, fixed-end-time problem. The idea is that by making the reactor temperature track the optimal temperature trajectory one may be able to produce polymer products having the prespecified physical property in a minimum time. The on-line control experiments with the PID control algorithm have been conducted to establish the validity of the scheme proposed in this study. The experimental results show that prespecified polymer product could be obtained with tracking the calculated optimal temperature trajectory.

• Journal of Biosystems Engineering
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• v.21 no.2
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• pp.155-166
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• 1996

A direct injection sprayer was designed using the concepts of injection mixing and total flow control, flowrate-based system compensating for the variation of forwarding speed. A metered rate, proportionally to the actual diluent flow rate, of a tracer chemical was injected directly into the diluent stream. The injection of chemical may improve the precision and safety of chemical application process. The control system was evaluated for the variables of the control interval, tolerances and sensitivities of flow regulation valve and injection pump. Performance of the system was assessed as that the response time of flow rate, response time of injection rate, absolute steady state error, and the coefficient of variance(C.V.) of concentration were 8.5 and -0.53 seconds, 0.067 lpm(0.8%) and 3.15%, respectively, at optimal parameters of control interval of 1.0 sec, fast sensitivity of flow regulation valve, medium sensitivity of injection pump and medium tolerance of flow rate. Performance of the system can be improved by increasing the sensitivity of flow regulating valve and employing a high resolution velocimeter, such as Doppler radar.

• Journal of Biosystems Engineering
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• v.19 no.2
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• pp.99-111
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• 1994

Automatic control system using microcomputer that have been studied in greenhouse, however, it was very difficult operation with success due to handicap for a various conditions and cultivated plants. This study was performed in order to develop of the basic program and hardware system for automatic control in greenhouse, such as automatic supplying of water, liquefied fertilizer solution and chemical solution. The results were summarized as follows. 1. The program for soil moisture control used by the switch type tensiometer was well operated. 2. The proximity switch was applied as well to water level control but it was very expensive, so low-priced sensor has to be developed. 3. The water meter was not excellent for mixing control of liquefied fertilizer, chemical and water, so water meter for only agricalture has to be developed. 4. Interface system for this study was suited to the developed controller. 5. Automatic control system to supply for water, liquefied fertilizer and chemical solution that was well operated as a fundamental study for product of controller.

• Journal of the Korean Institute of Gas
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• v.9 no.3 s.28
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• pp.15-20
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• 2005

Recently, Environmental and Safety Management is approaching in order to reduce the loss cost of accidents in effect, efficiency, excellency. In the side that is a large production enemy of the industrialization times, Most companies are focused on decreasing the loss that can let their companies grow healthily than a productivity improvement. The this study analyzed a matter asked f3r basic requirements and continuous development of ISO14001, OHSAS18001, PSM, Responsible Care operating in petro-chemical industries basically, and developed a LCMCI(the Loss Control Management system for Continuous Improvement of the Petro-chemical Industries) fer continuous development of petro-chemical companies in order to be able to continuously manage a loss.

• Journal of Physiology & Pathology in Korean Medicine
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• v.30 no.6
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• pp.397-401
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• 2016

The quality control is a fundamental procedure for the standardization of herbal medicine to guarantee the consistency of efficacy and safety. For a long time, the quality analysis of herbal medicine has been largely dependent on the routine sensory evaluation, such as taste, smell, color, and shape. However, with the recent development of analytical instruments, various scientific approaches have been introduced in this field. On the basis of the theory that the biological activities of herbal medicine are mainly contributed by its chemical compositions, several types of chemical markers have been suggested for the quality evaluation. In addition to the analytical methods for the specific marker compound(s), including analytical marker and active marker, recently, chemical fingerprinting, a method comparing the chromatographic pattern of the whole chemical components, has been developed and widely accepted as a reliable approach for the quality control of herbal medicine. Moreover, in order to exactly understand the relationship between complex compounds and their holistic biological activities in herbal medicine, unique strategies, such as "BECCs (bioactive equivalent combinatorial components)" and "PhytomicsQC" have been established. In this article, we give an overview of the several categories of chemical markers and the recent research trends for the quality evaluation of herbal medicine.