• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1309-1312
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• 2005

A multi-chemical supply system is developed and applied to a wet station, which uses the multi-chemical process in one bath. To control the concentration of two chemicals, control logic of a supply pump is programmed using the programable logic controller (PLC). By using the multi-chemical supply system, wet station with single bath is applied to cleaning process using multi chemicals such as buffed oxide etchant (BOE) and standard clean 1 (SC-1). The concentration of each chemical is measured in the bath to verify the multi-chemical supply system. The control range in the each chemical concentration is measured to 1.33weight% in NH4OH and 0.23weight% in H2O2. The multi-chemical supply system can be movable and usable as an independent module of fixed wet station. By simply midifying the PLC, a multi-chemical supply system can be developed for a wet station.

• The Journal of Asian Finance, Economics and Business
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• 제8권12호
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• pp.371-376
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• 2021

The article analyzes the impact of factors affecting the internal control system of chemical enterprises in Vietnam, providing more empirical evidence on factors affecting the system of internal control. Research data is collected in the form of face-to-face interviews and email interviews with managers and employees working in different positions, managers at all levels, chief accountants, and accountants of 52 chemical enterprises in Vietnam. The survey results collected 310 questionnaires. After eliminating the invalid questionnaires due to many blank cells, the authors chose to use 297 questionnaires. Quantitative research was carried out with SPSS 25 software. Research results show that Business Strategy, Organizational Structure, Organization's perception of the instability of the external environment, and Organizational culture are the factors that positively affect the internal control system of chemical enterprises. This can be explained that, for chemical enterprises, Business strategy, Organizational structure, Organization's perception of the instability of the external environment, and Good organizational culture will positively impact the internal control system of chemical enterprises. Based on the research results, the authors have proposed recommendations to enhance the effectiveness of the internal control system of chemical enterprises in Vietnam, thereby contributing to improving the performance of enterprises in the chemical Vietnamese.

• 한국응용과학기술학회지
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• 제26권2호
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• pp.151-160
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• 2009

At this study, we are developing a possible control system through remote monitoring for fire protection in various chemical factory facilities. It's possible to do real time confirmation of a normal operation presence of the various equipment installed in a chemical factory through the internet network at a fire fighting head office, an area fire department and a chemical factory situation room using this remote monitoring control system. When occurring, abnormal operation is the remote monitoring control system, which can check this immediately and notify the situation room administrator. After it was tested using developed remote monitoring control system, the remote monitoring for which the internet network was used confirmed possible.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.652-657
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• 1987

The Dynamic Matrix Control(DMC) technique was applied to nonlinear and nonminimum phase system. System model was identified by using Least Square method. Desired output trajectory was prespecified and input suppression parameter was also introduced. It was shown that DMC technique worked with great success in solving both nonminimum phase system and nonlinear system.

• Korean Chemical Engineering Research
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• 제58권3호
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• pp.430-437
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• 2020

본 연구에서는 다단제어(Cascade Control)를 위한 안티 와인드업(Anti-windup) 기술을 개발하였다. 다단제어는 외란을 보다 효과적으로 제어하기 위해 내부에 되먹임(Feedback) 제어루프를 추가한 제어구조이다. 단일루프제어(Single-loop Control)와는 다르게 두 개의 제어루프로 이루어져 내부의 종속제어루프(Secondary Control)가 외부의 주제어루프(Primary Control)에 영향을 미치는 특징을 가지고 있다. 산업현장에서 다단제어에 적용하는 기존의 안티 와인드업 기술은 주로 주제어기(Primary Controller)와 종속제어기(Secondary Controller)에 각각 로컬 역연산법(Back Calculation)을 적용하는 것이다. 하지만 이 방법은 종속제어기의 제어출력이 포화되었을 때 발생하는 주제어기의 적분누적(Integral-windup) 현상을 효과적으로 제거하지 못한다. 이를 해결하기 위해 기존 로컬 안티 와인드업 기술을 확대 적용한 두 가지의 다단제어용 안티 와인드업 기술을 제안한다. 첫 번째는 다단 조건부 적분법(Cascade Conditional Integration)이고 두 번째는 다단 역연산법(Cascade Back Calculation)으로 단일루프제어에 적용되어 왔던 로컬 조건부 적분법과 역연산법을 다단제어로 확대 적용하여 다단제어 시스템에서 PID제어기의 적분누적 현상을 방지하고자하였다. 개발한 다단 조건부 적분법과 다단 역연산법은 간단하고 직관적이면서도 종속제어기의 제어출력의 포화로 인해 발생한 적분누적현상을 효과적으로 방지할 수 있고 공정이나 제어기 형태에 상관없이 우수한 제어성능을 유지할 수 있었다. 향후 실제 공정 적용을 통해 신뢰성을 확보한다면 산업현장의 다단제어기 성능을 개선하는데 크게 기여를 할 수 있을 것이다.

• 공학교육연구
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• 제19권2호
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• pp.3-7
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• 2016

A flow control system was designed and fabricated to control the flow rate of liquid through the pipe. This control system was composed of hardwares and software, hardwares as controller, gate valve, orifice meter and data aquisition board and software as National instruments Labview program. Control of flow rate was executed by adjusting the pneumatic valve located at the center of pipe line based on the control signal generated by LabView PID control algorithm, which converts analog signal measured by pressure difference of orifice to digital signal to adjust pneumatic valve. For the controller setup Ziegler-Nichols tuning technique was applied and control performances were investigated for not only the disturbance but also the set point changes. Developed system showed good control performances in flow control enough to use as teaching tool of feedback control theory and practice in university, and also as industrial application.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.767-770
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• 2017

Quadruple tank liquid level systems are popular in testing multivariable control systems for multivariable processes with positive or negative zeros. The liquid level system is nonlinear and it will help to illustrate the robustness of control systems. However, due to nonlinearity, it can be cumbersome to obtain process parameters for testing linear control systems. Perturbation sizes are limited for valid linearized process models, requiring level sensors with high precision. A simple method where the outlet orifice is replaced to a long tube is proposed here. The effluent flow rate becomes proportional to the liquid level due to the friction loss of long tube and the liquid level system shows near linear dynamics. It is applied to the quadruple tank system for easier experiments.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.468-473
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• 1998

A mathematical model was developed for a continuous re-actor in which free radical polymerization of methyl methacrylate (MMA) occurred. Elementary reactions considered in this study were initiation, propagation, termination, and chain transfers to monomer and solvent. The reactor model took into account the density change of the reactor contents and the gel effect. A control system was designed for a continuous reactor using extended Kalman filter (EKF) based non-linear model predictive controller (NLMPC) to control the conversion and the weight average molecular weight of the polymer product. Control input variables were the jacket inlet temperature and the feed flow rate. For the purpose of validation of the control strategy, on-line digital control experiments were conducted with densitometer and viscometer for the measurement of the polymer properties. Despite the com-plex and nonlinear features of the polymerization reaction system, the EKF based NLMPC performed quite satisfactorily for the property control of the continuous polymerization reactor.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.815-824
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• 2012

분리할 성분들의 비점이 비슷하거나 공비를 형성하는 경우 일반적인 증류로 완전 분리가 불가능하다. 이를 극복하기 위하여 제 3성분을 가하여 상대 휘발도에 변화를 주는 추출 증류가 사용된다. 일반적으로 두 개의 증류탑으로 이루어진 추출 증류 공정이 사용되나 열 통합된 연속식 증류탑으로 이루어진 추출 열 통합 증류 공정은 보다 에너지 효율이 높고 장치비가 절감되는 장점을 가지고 있다. 그러나 추출 열 통합 증류 공정은 종래의 추출 증류 공정에 비하여 운전 및 제어가 어려워 널리 사용되지 못하고 있다. 본 논문에서는 이러한 단점을 극복할 수 있도록, 또한 외란에 대하여 안전한 조업이 이루어지도록 할 목적으로 최적 조업조건에서의 추출 열 통합 증류 공정의 운전 및 제어를 연구하였고 여러 가지의 제어 구조를 제안하였다. 제안된 제어구조 중에 프로필 위치 제어가 가장 좋은 제어 성능을 나타내었다.

• 대한환경공학회지
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• 제39권11호
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• pp.650-654
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• 2017

화학물질의 취급량 증가에 따라 화학물질 관리 제도를 전면적으로 개편하는 움직임이 국제적으로 일어나고 있다. 한국 역시 화학물질 관리 제도를 전면 개편하여 화학물질관리법과 화학물질 등록 및 평가에 관한 법률이 제정되었다. 하지만 화학물질관리법의 경우, 법 시행 4년째를 앞두고 여러 개선사항이 드러나고 있다. 따라서 본고에서는 화학물질관리법의 제언한 개선사항에 대한 보완점을 연구하고 그에 맞는 발전방향을 제시하여 화학물질관리법이 오랫동안 안전한 화학물질 관리제도로서 대내외에 널리 도입되고 연구되었으면 하는 바람이다.