• Environmental Analysis Health and Toxicology
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• v.18 no.1
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• pp.63-67
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• 2003

Benzoic acid is produced about 700 tons/year in Korea as of 1998 survey. Most is used as a stabilizer in the processes of synthesis of pharmaceuticals and dyes. It is also used for ingradient of paint, disinfections, and antifungals. Due to the antioxidant activity of benzoic acid, the chemical is also used as food preservatives. Although the chemical is widely used in Korea, exposure levels in air, water, soil or sediment have not been monitored or estimated so that risk evaluation of benzoic acid was not possible. In this study, distribution of the chemical among environmental media was estimated using EQC model based on the chemical-physical properties. In Level I and II of which the chemical are hypothesized in equilibrium and no transfer through the media, more than 93％ of benzoic acid are estimated to be distributed in water. However, in Level III of which non-equilibrium and intermedia transfer could be occurred, the chemical is estimated to distributed to soil, 64％ and water,35% as of total amount.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3583-3589
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• 2014

This study evaluated a simple and useful route to the synthesis of mesoporous $TiO_2$ microcapsules with a hollow macro-core structure. A hydrophilic precursor sol containing the surfactants in the hydrophobic solvents was deposited on PMMA polymer surfaces modified by non-thermal plasma to produce mesoporous shells after calcination. The surface of the PMMA polymer spheres was coated with $NH_4F$ and CTAB to control the interfacial properties and promote the subsequent deposition of inorganic sols. These hollow type mesoporous $TiO_2$ microcapsules could be applied as an efficient substrate for the immobilization of DNA oligonucleotides.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.750-753
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• 2002

The chemical vapor condensation process of Parylene-N thin films was investigated and applied to the passivation of the organic light emitting diodes (OLEDs). The effects of process variables on the deposition rate were studied, and it was found that the deposition rate of Parylene increases with increasing precursor sublimation temperature but decreases with increasing substrate temperature. The Parylene film was used as a passivation layer for OLEDs, and as a result, the lifetime of the passivated OLEDs was increased by a factor of about 2.3 compared with that of non-passivated OLEDs.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.02a
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• pp.314-314
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• 2008

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.3
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• pp.167-172
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• 2003

Foam fractionation can be used to enrich a hydrophobic protein such as bromelain from an aerated dilute protein solution because the protein foams. On the other hand, a protein such as invertase, which is hydrophilic, is not likely to foam under similar aerated conditions. While a foam fractionation process may not be appropriate for recovering a hydrophilic protein alone, it is of interest to see how that non-foaming protein affects the foaming protein when the two are together in a mixture. The bromelain enrichment, activity and mass recovery were observed as a function of the solution pH in order to explore how invertase can affect the recovery of bromelain in a foam fractionation process.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.501-506
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• 1998

A mathematical model is developed to describe the relationship between the manipulated variables (e.g. jacket inlet temperature and feed flow rate) and the important qualities (e.g conversion and weight average molecular weight (Mw)) in a continuous polymerization reactor. The subspace-based identification method for Wiener model is used to retrieve from the discrete sample data the accurate information about both the structure and initial parameter estimates for iterative parameter optimization methods. The comparison of the output of the identified Wiener model with the outputs of a non-linear plant model shows a fairly satisfactory degree of accordance.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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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 Journal of Environmental Agriculture
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• v.29 no.4
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• pp.354-361
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• 2010

Soil physico-chemical properties and microbial densities are affected by organic sources and soil amendment applied to improve soil environments or quality. Generally organic fertilizer effects on forage crops yield and soil properties are partly due to changes of soil composition. We investigated the effects of swine slurry (SS), swine slurry composting-biofilteration(SCB) and chemical fertilizer(F) with gypsum(G) combinations on soil physico-chemical properties and yields of summer forage crop in the Sukmoon reclaimed tidal land in Korea. The forage crops used in this experiment were corn and sorghum$\times$sudangrass hybrid(hereafter sorghum). Our results showed that the soil physico-chemical properties in the combined (F+G, SS+G, SCB+G) treatments increased contents of organic matter and exchangeable $Ca^{2+}$, but exchangeable $Na^+$, $K^+$ and $Mg^{2+}$ reduced to 1-10% for two forage crops, compared to non-combined (F, SS, SCB) treatment. The density of soil microorganism such as bacteria, actinomycetes and fungi, increased significantly by SS+G and SCB+G treatments. This means that treatment of combined organic fertilizer with G lowered salinity levels and improved with microbial growth. The combined treatments also increased the total yields 2.3-6.2% for corn and 2.0-8.7% for sorghum, compared with non-combined treatment. This experiment suggests the combined treatments could increase the total yields of summer forage crops and change of soil physico-chemical properties in the Sukmoon reclaimed tidal land in Korea.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.214-219
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• 2017

In this work, we fabricated PS-b-P4VP block copolymer membranes from self-assembly and non-solvent induced phase separation (SNIPS), which combines the block copolymer self-assembly and conventional NIPS process. While previous studies mostly focused on the fabrication of well-defined structures, we systematically examined various processing parameters such as polymer concentration, solvent evaporation duration, solvent composition, and humidity, to optimized the membrane structures. As a result, the morphology of PS-b-P4VP membranes was optimized at a certain polymer concentration in solution and composition of volatile solvent at low humidity conditions, resulting in SNIPS separation membranes with well-defined nanopores on the surface, 75% of membrane porosity, and 18% of surface porosity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.85-96
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• 2003

For a design of rocket engine nozzle, chemical equilibrium analysis which shares the same numerical characteristics with frozen flow analysis can be used as an efficient design tool for predicting maximum thermodynamic performance of the nozzle. 10 this study, a chemical equilibrium flow analysis code was developed for the design of hydrocarbon fueled rocket engines. 10 oder to understand the thermochemical characteristics occurring in a nozzle through the expansion process, such as recombination of chemical components and the accompanying energy recovery, chemical equilibrium flow analysis was carried out for the KSR-III rocket engine nozzles together with frozen flow and non-equilibrium flow analyses. The performance evaluation based on the present KSR-III nozzle flow analyses has provided an understanding of the thermochemical process in the nozzle and additionally, it has confirmed that the newly designed nozzle shape modified to have a reduced exit area ratio is an adequate design for obtaining an increased ground thrust.