• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1000-1003
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• 1996

Nonlinear unified predictive control(UPC) algorithm was applied to the temperature control of a batch polymerization reactor for polymethylmethacrylate(PMMA). Before the polymerization reaction is initiated, the parameters of the process model are determined by the recursive least squares(RLS) method. During the reaction, nonlinearities due to generation of heat of reaction and variation of heat transfer coefficients are predicted through the nonlinear model developed. These nonlinearities are added to the process output from the linear process model. And then, the predicted process output is used to calculate the control output sequence. The performance of nonlinear control algorithm was verified by simulation and compared with that of the linear unified predictive control algorithm. In the experiment of a batch PMMA polymerization, nonlinear unified predictive control was implemented to regulate the temperature of the reactor, and the validity of the nonlinear model was verified through the experimental results. The performance of the nonlinear controller turned out to be superior to that of the linear controller for tracking abrupt changes in setpoint.

• 한국환경과학회지
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• 제20권1호
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• pp.35-47
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• 2011

The effect of the variation of aeration time on the removal of organics, nitrogen and phosphorus using synthetic wastewater was investigated in sequencing batch reactors (SBRs) which included DNPAOs and DNGAOs. The cycling times in four SBRs were adjusted to 12 hours and then included different aerobic times as 1 hr, 2.5 hr, 4 hr and 5.5 hr, respectively. Four SBR systems have been operated and investigated for over 40 days. Average TOC removal efficiencies were about 71 % in all SBRs. The $NH_4^+$-N removal efficiency was increased as the increase of aeration time. After changing aeration time, the total nitrogen removal efficiencies of SBRs were shown as 35 %, 85 %, 75 % and 65 %, respectively. Higher phosphorus release and uptake were occurred as the decrease of the aeration time. After all, the overall phosphorus removal efficiency decreased and the deterioration of phosphorus removal was occurred when aeration time was over 4 hr. Denitrification in aerobic conditions was observed, which showed the presence of DNPAOs and DNGAOs. In batch experiments, PAOs were shown as the most important microorganisms for the phosphorus removal in this experiment, and the role of DNGAOs was higher than that of DNAPOs for the nitrogen removal.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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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.

• 한국안전학회지
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• 제27권5호
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• pp.77-87
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• 2012

Compared to a batch reactor, where all reactants are initially charged to the reactor, the semi-batch reactor presents serious advantages. The feed of at least one of the reactants provides an additional way of controlling the reaction course, which represents a safety factor and increases the constancy of the product quality. The aim of this study was to investigate the characteristics of thermal hazard such as a feed time, catalysis concentration and solvent concentration in methylthioisocyanate(MTI) synthesis reaction process. The experiments were carried out by the Multimax reactor system and Accelerating rate calorimeter(ARC). The MTI synthesis reaction process has many reaction factors and complicated reaction mechanism of multiphase reaction. Through this study, we can use as a tool for assessment of thermal hazard of other reaction processes by applying experiment method provided.

• 한국연소학회지
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• 제18권2호
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• pp.17-22
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• 2013

In this study, we tested the absorption of $CO_2$ in combustion gas into an alkaline wastewater to simultaneously control $CO_2$ and wastewater. During the experiment, we investigated the effects of operating parameters on neutralization characteristics of the wastewater by using $CO_2$ in a bench-scale semi-batch jet loop reactor (0.1 m diameter and 1.0 m in height). The operating parameters investigated in the study are gas flow rate of 1.0-2.0 L/min, liquid recirculation flow rate of 4-32 L/min, and liquid temperature of $20-25^{\circ}C$. It was shown that the initial pH of wastewater rapidly decreased with increased gas flow rate for a given liquid recirculation flow rate. This was due to the increase in the gas holdup and the interfacial area at higher gas flow rate in the reactor. At constant gas flow rate, the time required to neutralize the wastewater initial pH of 10.1 decreased with liquid recirculation flow rate ($Q_L$), reached a minimum value in the range of $Q_L$ = 16-24 L/min, and then increased with further increase in $Q_L$. Further, the time required to neutralize the wastewater was shortened at higher temperatures.

• 한국연소학회지
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• 제18권3호
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• pp.38-43
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• 2013

In this study, we tested the absorption of $CO_2$ in combustion gas into an alkaline wastewater to simultaneously control $CO_2$ and wastewater. During the experiment, we investigated the effects of operating parameters on neutralization characteristics of the wastewater by using $CO_2$ in a bench-scale semi-batch jet loop reactor (0.1 m diameter and 1.0 m in height). The operating parameters investigated in the study are gas flow rate of 1.0-2.0 L/min, liquid recirculation flow rate of 4-32 L/min, and liquid temperature of $20-25^{\circ}C$. It was shown that the initial pH of wastewater rapidly decreased with increased gas flow rate for a given liquid recirculation flow rate. This was due to the increase in the gas holdup and the interfacial area at higher gas flow rate in the reactor. At constant gas flow rate, the time required to neutralize the wastewater initial pH of 10.1 decreased with liquid recirculation flow rate ($Q_L$), reached a minimum value in the range of $Q_L$ = 16-24 L/min, and then increased with further increase in $Q_L$. Further, the time required to neutralize the wastewater was shortened at higher temperatures.

• 상하수도학회지
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• 제8권3호
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• pp.1-8
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• 1994

In the general process of design for aerobic digestion, the design for field plant of which inflow pattern is continuous inflow is performed using the results from lab scale batch reactor. However, the recent researchers reported that the general designs were performed as over-estimated, Therefore, in this study, laboratory batch experiments were carried out at $20^{\circ}C$ and pH 7.5 on the aerobic digestion of waste activated sludge at different solid levels. This treatise could consider the negligence about effective digestion periods the usage of VSS as solid concentration, and the effect of initial solid concentration of solid degration rate coefficient($k_d$) as reasons of the overestimated design, and showed the scheme of how to design for aerobic digestion from batch experiment.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권5호
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• pp.291-293
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• 2003

Batch reactors were employed to investigate the kinetics of cellulose hydrolysis under extremely low acid (ELA) and high temperature condition. The sawdust was pretreated by Auto-hydrolysis prior to the batch reaction. The maximum yield of glucose obtained from the batch reactor experiment was about 70% for the pretreated sawdust, this occurred at 210 and 22$0^{\circ}C$. The maximum glucose yield from the untreated sawdust was much lower at these temperatures, about 55%. The maximum yields of glucose from the lignocellulosics were obtained between 15th and 20th minutes after which gradual decrease was observed.

• 한국지반환경공학회 논문집
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• 제15권8호
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• pp.45-50
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• 2014

하수관 내에서의 하수와 미생물의 반응에 대한 실험은 이미 매설된 하수관에 적용할 경우 실험조건의 변화가 제한적이며 실험시간에도 한계가 있다. 본 연구에서는 이러한 하수관 내에서의 하수와 미생물의 반응에 대하여 DO를 제한 조건으로 설정하였을 경우, 실험실 내에서 실험반응조를 통해 재현하는 방법에 대하여 연구하였다. 하수관 내에서의 DO 농도는 기상 중의 산소가 하수 내로 이동하는 재포기현상에 의해 조절된다. 이러한 현상을 이용하여 임의로 실험반응조에서 하수관 내의 유하조건을 조절하고 재포기현상을 재현하여 유하조건과 재포기계수와의 상관관계를 얻을 수 있으며, 교반강도(속도경사)에 따른 재포기계수와 하수관거에서의 유하조건에 따른 재포기계수의 상관관계를 통해 동일한 재포기계수 값을 갖는 교반강도와 유하조건을 설정할 수 있다. 이러한 결과를 통해 재포기계수를 제한인자로 설정하여 실험을 실시할 경우 하수관거에서의 상황을 실험반응조를 통해 재현할 수가 있었다.

• 한국환경과학회지
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• 제6권6호
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• pp.697-709
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• 1997

Sequencing Batch Reactor(SBR) experiments for organics and nutrients removal have been conducted to find an optimum anaerobic/anoxic/aerobic cycling time and evaluate the applicability of oxidation-reduction potential(ORP) as a process control parameter. In this study, a 61 bench-scale plant was used and fed with night-soil wastewater in K city which contained TCODcr : 10, 680 mg/l, TBm : 6, 893 mg/l, $NH_4^+-N$ : 1, 609 mg/l, $PO_4^{3-}-P$ : 602 mg/l on average. The cycling time In SBRs was adjusted at 12 hours and 24 hours, and then certainly included anaerobic, aerobic and inoxic conditions. Also, for each cycling time, we performed 3 series of experiment simultaneously which was set up 10 days, 20 days and 30 days as SRT From the experimental results, the optimum cycling time for biological nutrient removal with nlght-soil wastewater was respctively 3hrs, 5hrs, 3hrs(anaerobic-aerobic-anoxic), Nitrogen removal efficiency was 77.9%, 77.9%, 81.7% for each SRT, respectively. When external carbon source was fed in the anoxic phase, ORP-bending point indicating nitrate break point appeared clearly and nitrogen removal efficiency increased as 96.5%, 97.1%, 98.9%. Phosphate removal efficiency was 59.8%, 64.571, 68.6% for each SRT. Also, we finded the applicability of ORP as a process control parameter in SBRs.