• Clean Technology
• /
• v.16 no.2
• /
• pp.73-79
• /
• 2010

Vinyl acetate(VAc) was dispersion-polymerized using supercritical carbon dioxide that has many environmental advantages. To get poly(vinyl acetate) (PVAc) of larger molecular weights from conventional emulsion polymerization, VAc was polymerized at temperatures between 333.15 and 343.15 K and pressures between 20 and 40 MPa with initiator (0.5 ~ 5% of monomer) and silicone-based stabilizer (1 ~ 10% of monomer) for 2 ~ 50 hr. The resulting PVAc was analyzed to see the variations in the yield and the molecular weight. The final product of this research, PVA (poly(vinyl alcohol)), was prepared from PVAc by saponification. The effect of saponification conditions on the yield and the molecular weight of polymer were also studied.

• Clean Technology
• /
• v.18 no.2
• /
• pp.123-143
• /
• 2012

Supercritical fluid technology (SFT) is recently one of the most new techniques, which has been interested various fields of related chemical industries. SFT is the most effective and practical technology with eco-friendly, energy-savings, and high efficiency as the technique using the advantages of supercritical fluid such as high solvation power, solubility, mass transfer rate, and diffusion rate. Especially, it is necessary to analyze, evaluate, and develop the potential of application techniques using SFT with these characterizations. Therefore in this review, the phase behavior in supercritical fluid at high temperature and pressure of monomers/polymers for the optimization of polymerization process are briefly described, and the preparation of molecularly imprinted polymers (MIPs) in supercritical fluid using supercritical polymerization and the performance evaluation of MIPs are introduced.

• 제어로봇시스템학회:학술대회논문집
• /
• 1988.10a
• /
• pp.471-475
• /
• 1988

Pressure and flowrate control systems for a supercritical extraction process are designed and analyzed. To do this, the dynamic model was first set up using the performance equations of control valves, CO2 compressor and the state equation of the supercritical fluid. Using this model, optimum pairs of manipulated and controlled variable which give least steady stat interaction are determined though the relative gain analysis.

• Journal of the Korea Convergence Society
• /
• v.11 no.5
• /
• pp.241-251
• /
• 2020

This study was performed to develop the cosmetics containing extract of U.davidiana, which has been confirmed as a functional ingredient of anti-microbial, anti-oxidant, and anti-inflammatory effects, and also to evaluate the improvement effects of dry and sensitive skin such as atopic dermatitis. Toxicity tests of the Ulmus davidiana supercritical fluid residue 60% EtOH extracts(USCFR), Ulmus davidiana supercritical fluid extracts(USCF) and preliminary formulations, DKBP-1903(gel), containing the USCFR and USCF were determined to be 'Non-toxic'. Based on this, the stability test of the lotion, cream, gel formulation was conducted and the results showed that cream and gel formulation were stable. A 48-hour moisturizing sustainability test and the improvement test on the pruritus caused by dryness were selected for the cosmetic efficacy test to evaluate the improvement of atopic dermatitis and as a result both cream and gel have been found to be relatively safe moisturizers that can help dry and sensitive skin.

• Applied Chemistry for Engineering
• /
• v.16 no.1
• /
• pp.28-33
• /
• 2005

A resource recovery technique using sub- and supercritical water hydrolysis was applied to recover amino aicds from waste fish entrails. The effect of reaction parameters such as temperature and time necessary for the control of reaction towards optimum yield of amino acids was investigated using semi-batch and batch reactors. Results showed a maximum yield of total amino acids (137 mg/g-dry entrails) from waste fish entrails at T=$250^{\circ}C$ (P=4 MPa) and reaction time of 60 min in a batch reactor. Under supercritical conditions (e.g., T=$400^{\circ}C$, P=45 MPa), the yield decreased due to rapid decomposition compared to production rate of amino acids. As a result, the low temperature and the short reaction time were needed to produce a maximum yield of amino acids.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.6
• /
• pp.1-11
• /
• 2021

To develop an efficient procedure related to the flamelet library, the machine learning process based on artificial neural network(ANN) is applied for the gaseous hydrogen/liquid oxygen combustor under a supercritical pressure condition. For hidden layers, 25 combinations based on Rectified Linear Unit(ReLU) and hyperbolic tangent are adopted to find an optimum architecture in terms of the computational efficiency and the training performance. For activation functions, the hyperbolic tangent is proper to get the high learning performance for accurate properties. A transformation learning data is proposed to improve the training performance. When the optimal node is arranged for the 4 hidden layers, it is found to be the most efficient in terms of training performance and computational cost. Compared to the interpolation procedure, the ANN procedure reduces computational time and system memory by 37% and 99.98%, respectively.

• Proceedings of the Korean Aquaculture Society Conference
• /
• 2006.05a
• /
• pp.113-114
• /
• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.1211-1212
• /
• 2013

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2004.04a
• /
• pp.235-239
• /
• 2004

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2004.04a
• /
• pp.244-247
• /
• 2004