• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.461-467
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• 1998

In spite of significant nonlinearities even in the simplest model, some types of steady-state and dynamic behavior common for nonlinear systems have never been associated with distillation columns. In recent years, multiplicity of steady states has been a subject of much research and is now widely accepted. Subsequently, stability of steady states has been explored. Another phenomenon that. although widely observed in chemical reactors, has not been associated with models of distillation columns is the existence of periodic oscillations. In this article we study the steady-state and dynamic behavior of the azeotropic distillation of the ternary homogeneous system methanol-methyl butyrate-toluene. Our simulations reveal nonlinear behavior not reported in earlier studies. Under certain conditions, the open-loop distillation system shows a sustained oscillation associated with branching to periodic solutions. The limit cycles are accompanied by traveling waves inside the column. Significant underdamped oscillations are also observed over a wide range of product rates.

• Journal of Food Hygiene and Safety
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• v.20 no.3
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• pp.134-140
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• 2005

Boiling point and distillation range, melting range, and identification methods in general test method of Korea, Japan, Joint FAO/WHO Expert Committee of Food Additives (JECFA), and USA on chemical food additives were compared. Boiling point of propylene glycol was indicated as boiling point in Korea, distillate in Japan, distillation range in JECFA and USA, and its value was up to the standard. Distillation range of propionic acid was indicated as distillate in Korea and Japan, distillation range in JECFA and USA, and its value was up to the standard. There is no standard on distillation range of isopropyl alcohol in Japanese method. Test method of melting range on synthetic food additives was identical in all organizations, and there are 28 items to which this test method applies in Korean Food Additives Code. The standards on molting range of D-mannitol were different in various organizations, and in USA method there are no standards to which L-ascorbic acid, calciferol, and fumaric acid apply. Synthetic food additives performing the identification test were 251 items in Korean Food Additives Code, but there are no items to which manganese, glycerophosphate, bromate, thiosulfate, and bromide apply. Calcium benzoate was dissolved by heating in benzoate test and we could not identify the citrate in ferric citrate by method (2) of Korea and Japan. Identification test methods for ammonium, lactate, magnesium, copper, sulfate, phosphate, and zinc were identical in all organizations, and these could be identifed by current identification methods.

• Membrane and Water Treatment
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• v.9 no.6
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• pp.435-445
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• 2018

In this work, desalination experiments were performed on vacuum membrane distillation (VMD). Process parameters such as feed flow rate, vacuum degree on permeate side, feed bulk temperature and feed salt concentration were optimized using sensitivity analysis and Taguchi method. The optimum values of process parameters were found to be 2 lpm of feed flow rate, $60^{\circ}C$ of feed bulk temperature, 5.5 kPa of permeate-side pressure and 5000 ppm of salt concentration. The permeate flux at these conditions was obtained as $26.6kg/m^2{\cdot}hr$. The rejection of salt in permeate was found to be 99.7%. The percent contribution of various process parameters using ANOVA results indicated that the most important parameter is feed bulk temperature with its contribution of 95%. The ANOVA results indicate that the percent contribution of permeate pressure gets increased to 5.384% in the range of 2 to 7 kPa as compared to 0.045% in the range of 5.5 to 7 kPa.

• Membrane and Water Treatment
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• v.4 no.4
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• pp.223-236
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• 2013

The paper presents an experimental set-up for osmotic membrane distillation, which can be operated continuously for several weeks. NaCl solutions were used as an osmotic solution. The influence of osmotic solution concentration on the obtained permeate flux is presented. The experimental set-up was equipped with a system for the regeneration of dilute brine. The regeneration was carried out using a method of natural evaporation to the air surrounding the installation. The evaporation area was created by the Białecki rings, assembled in the form of tower. The obtained evaporation rate was sufficient to maintain a constant NaCl concentration (over 300 g/L), for air with the relative humidity in the range of 30-80%. Accurel PP S6/2 hydrophobic polypropylene membranes were used in the study. The membranes exhibited 100% rejection for 600 h of the process duration.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.550-564
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• 2020

Distillation columns are one of the main equipment used for the separation of chemical components in petrochemical process design. However, in spite of the efficient operation in wide range, and the advantage of data collection for equipment verification, the distillation columns are inherently known for high energy consumption and capital cost. Hence, the trade-off analysis needs to be done between investment cost and operation cost to develop the most economical distillation columns. This study was conducted using Aspen Plus, a popular process simulation program, in the pursuit of broad application by as many process engineers as possible. In this paper, design variables for optimization of distillation columns were defined to improve emphatically the design quality with reducing erratic practice of many engineers. In addition, by eliminating unnecessary reviewing step and establishing systematic and efficient procedures, the amount of time for design and human resources were minimized. Aspen Process Economic Analyzers (APEA) program was introduced in order to calculate the investment cost reliably, and the efficient systematic procedure for utilization of APEA was established.

• The KSFM Journal of Fluid Machinery
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• v.16 no.1
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• pp.56-60
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• 2013

Non-conventional oil resources such as shale gas are becoming increasingly important and have drawn the attention of several major oil companies all over the world. Nevertheless, the market-changing growth of shale gas production in recent years has resulted in the emergence of environmental and water management challenges. This is because the water used in the hydraulic fracturing process contains large amount of pollutants including ions, organics, and particles. Accordingly, the treatment of this flowback water from shale gas plant is regarded as one of the key technologies. In this study, we examined the feasibility of membrane distillation as a treatment technology for the water from shale gas plants. Direct contact membrane distillation (DCMD) is a thermally-driven process based on a vaper pressure gradient across a hydrophobic membrane, allowing the treatment of feed waters containing high concentration of ions. Experiments were carried out put in the lab-scale under various conditions such as membrane types, temperature difference, flow rate and so on. Synthetic feed water was prepared and used based on the data from literature. The results indicated that DCMD is suitable for treating not only low-range flowback water but also high-range flowback water. Based on the theoretical calculation, DCMD could have over 80% of recovery. Nevertheless, organic pollutants such as oil and surfactant were identified as serious barriers for the application of MD. Further works will be required to develop the optimum pretreatment for this MD process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.21-27
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• 2018

FRN (Full range Naphtha) is distilled from crude oil in a Naphtha Splitter Unit and is separated into the Light Straight Naphtha, Heavy Naphtha, and kerosene according to the boiling point in sequence. This separation is conducted using a series of binary-like columns. In this separation method, the energy consumed in the reboiler is used to separate the heaviest components and most of this energy is discarded as vapor condensation in the overhead cooler. In this study, the first two columns of the separation process are replaced with the Petlyuk column. A structural design was exercised by a stage to stage computation with an ideal tray efficiency in the equilibrium condition. Compared to the performance of a conventional system of 3-column model, the design outcome indicates that the procedure is simple and efficient because the composition of the liquid component in the column tray was designed to be similar to the equilibrium distillation curve. An analysis of the performance of the new process indicated an energy saving of 12.3% under same total number of trays and with a saving of the initial investment cost.

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.181-192
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• 2015

The aim of this study is to obtain optimum process condition for using two tower distribution to recycle the waste Propylene Glycol Monomethyl Ether Acetate (PGMEA) that is formed after washing LCD. The optimum process condition for the content of PGMEA, which is dependent variable, at 1st distillation was calculated according to Bottom temperature (BTM temperature), Reflux amount, Feed amount, Feed temperatures, and the optimum process conditions and optimum factors for the content of PGMEA at 2nd distillation according to Bottom temperature (BTM temperature), Reflux amount, Feed amount, Feed temperatures. At 1st distillation, Reflux amount, Feed amount, and Feed temperature are significant variables. However, it is found that the BTM temperature range is not significant in the range of process condition used in this study. The optimum process conditions are based on $5700{\ell}$ of Feed amount, $2500{\ell}$ of Reflux amount, $165^{\circ}C$ of BTM temperature, and $130^{\circ}C$ of Feed temperature. For the this condition, the predicted content of PGMEA was calculated as 92.12~94.62%. Significant factors at 2nd distillation are Reflux amount, Feed amount, and BTM temperature. Multicollinearity is between Reflux amount and BTM temperature. BTM was omitted in the multiple regression equation because there is a strong positive correlation between Reflux amount and BTM temperature. Base on $199^{\circ}C$ of BTM temperature, The optimum process conditions are based on $4275{\ell}$ of Feed amount, $6200{\ell}$ of Reflux amount and $130^{\circ}C$ of Feed temperature. In this condition, the predicted content of PGMEA was calculated as 99.0~99.5%.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.631-636
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• 2022

Alcohol content, which is an important standard for Takju, a traditional multiple parallel fermentation liquor called makgeolli, is a factor that can affect the flavor. For alcohol content analysis, the distillation/hydrometry technique is mainly used. In this study, we analyzed the alcohol content of 14 commercially available Takju by the distillation/hydrometry technique and the improved GC method, respectively, after verifying the reliability of improved GC method. The precision and accuracy of the GC method were satisfactory, and LOQ and LOD were evaluated as 0.5% and 0.1% of ethanol contents, respectively. Among the three Takju exceeding the labelled alcohol content ±1, one Takju was quantitated as alcohol content 9.9% (by GC method) and 10.1% (distillation/hydrometry technique) exceeding labelled 6.0%. It was within the analytical error range of alcohol content for other two Takju, where the alcohol contents were exceeded -1.1%. The average precision (%RSD) of 14 Takju analyzed by the distillation/hydrometry technique (36.2%) and the GC method (12.8%), confirming that the GC method was better than the other. The improved GC method was evaluated to be effective in managing and improving the alcohol content standard of Takju with the wide range of alcohol content.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1028-1032
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• 2003

To assess accurate methods for measuring sulfur dioxide residue in pickles, the acid distillation HPLC-UV method and Monnier Willams modified method were examined. By the acid distillation HPLC-UV method, sulfites released from pickles by acid distillation were absorbed in 1% triethanolamine solution and detected as sulfite ion by HPLC with UV monitoring at 240nm. An anion exchange column was employed with 1.8mM $Ma_2CO_3-1.7mM\;NaHCO_3$ solution as a mobile phase, $84.0{\sim}91.7%$ of sulfite added to pickled radish were recovered. Total sulfite levels from 48 kinds of pickles analyzed by acid distillation HPLC-UV was compared with those analyzed by the Monnier Williams modified method. The Monnier Williams modified method showed higher levels of sulfur dioxide than the acid distillation HPLC-UV method due to the presence of volatile acids in pickles. The concentration of sulfur dioxide was in the range of $N.D{\sim}173.05ppm$ in pickled radish and over 30ppm of sulfur dioxide from 3 samples by the acid distillation-HPLC-UV method.