• Journal of the Korean Chemical Society
• /
• v.36 no.6
• /
• pp.914-918
• /
• 1992

The preferential transport phenomena of neutral cation-anion moieties in neutral macrocycle-facilitated emulsion liquid membrane were described in this study. Emulsion membrane systems consisting of (1) aqueous source phase containing 0.001M $M(NO_3)_2$ (M = $Mn^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Sr^{2+}$, $Cd^{2+}$, $Pb^{2+}$) (2) a toluene membrane containing 0.02M ligand (DB$N_3O_2$, DB18C6) and the surfactant span 80 (sorbitan mono oleate) (3% v/v) and (3) aqueous receiving phase containing $Na_2S_2O_3$ or $NaNO_3$ were studied with respect to the disappearence of metal ions from the source phase as a function of time. Cation transport rates for various two component equimolar mixture of metal ions were determinded. $Cd^{2+}$ was transported higher rates than the other $M^{2+}$ in the mixture solution.

• Korean Journal of Agricultural Science
• /
• v.14 no.1
• /
• pp.81-97
• /
• 1987

Two nozzles with different size (Figure 2) were particularly designed to supply air through the swirl core into the central part of the liquid stream in the same parallel direction to produce a well-mixed air and water in the whirl chamber as spray liquid in bubble formation. Atomization was attempted to improve by using both the preliminary break-up process with less viscosity and less surface tension in the whirl chamber and the effects of increased frequency of the band of drops with the raised ambient air density in front of the nozzle orifice. The volumetric ratio between spray liquid and air on four levels was used to investigate the effects of air as a component of the mixture on atomization. The results of the experiment were summarized as follows; Droplet size became progressively finer as the operating pressure was increased in the range of $0.70kg/cm^2$ to $6.33kg/cm^2$, which was similar to the previous works. The new atomizing mechanism so-called 'air-center nozzle' gave a narrower range in droplet size distribution with smaller volumetric median diameter (VMD) than that of the existing spray system at a given pressure, which showed the possibility of improvement of atomization in a certain limit. The volumetric median diameter produced by the new atomizing mechanism was decreased from the central region toward the exterior edges across the spray pattern.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.44 no.2
• /
• pp.201-210
• /
• 2018

In this study, we formulated oil-in-water emulsion composition for skin care products containing jadeite powder which is well known as far-infrared radiating material. Jadeite powder could sustain stable dispersion in aqueous solvents over a month and this helped mixing it high content in oil-in-water emulsion formulation. To identify the effect of jadeite as a far-infrared radiator materials relating to the skin surface temperature change, we applied emulsion formulation containing 2 weight percent jadeite powder onto facial skin surface and blank formulation together and analyzed surface temperature with thermo-vision. Our results showed that the temperature difference between jadeite powder formulation applied region and blank formulation reached to 1.5 ~ 2.0 degree Celsius. We also performed same test with nephrite powder and titanium dioxide powder but only jadeite powder containing formulation showed significant skin temperature change. To elucidate main cause of heat energy transfer, we tested heat radiation, energy dispersive spectrometer analysis and measured far infrared radiance emissivity, diffuse reflectance spectra and water evaporation rate. We found out jadeite powder could retard water evaporation effectively from the skin surface and resist temperature drop down. This is because of the innate chemical composition and surface structure of jadeite, which can bind with water molecules to form hydrogen bonds. It is concluded that we can develop novel skin care products for moisturizing and thermos with jadeite powder.

• Food Science and Preservation
• /
• v.16 no.1
• /
• pp.75-81
• /
• 2009

Benzo(a)pyrene[B(a)P] levels were determined in processed oils and by-products of corn oil, and removal protocol was formulated. The cause of high level B(a)P contents in corn oil was established. Corn germ had a B(a)P level more than 80% that of whole corn. B(a)P content in final deodorized corn oil was $2.15{\mu}g/kg$, after the usual refining process. B(a)P contents less than $2.0{\mu}g/kg$ could not be attained by routine refining process. However, deodorized corn oil, with B(a)P level of $0.09{\mu}g/kg$, could be prepared by treatment of oil with approximately 2% (w/w) mixed granules(acidic clay:active carbon= 90:10[w/w]). The optimal amount of active carbon was 10% (w/w) that of acidic clay;higher levels of active carbon was not required. The optimal particle size of active carbon was $50{\sim}100$ mesh, removal of B(a)P from bleached corn oil was efficient at this mesh size.

• Clean Technology
• /
• v.24 no.1
• /
• pp.50-54
• /
• 2018

In this work, N-methyl-2-pyrrolidone (NMP) was added into diethylenetriamine (DETA) aqueous solution for high $CO_2$ loading via phase splitting of absorbents during $CO_2$ absorption. Immiscible two phases were formed in the range of more than 30 wt% of NMP in 2 M DETA + NMP + water absorbents because of low solubility of DETA-carbamate in NMP solution. As the composition of NMP in the absorbents increased, the difference of $CO_2$ loading between each phase increased and the volume of bottom phase decreased. In $CO_2$ absorption in packed column by 2 M DETA + NMP + water absorbents, the absorption rate decreased in the range of more than 40 wt% of NMP. It is due to the increasing of mass transfer resistance in liquid film of absorbents at the high concentration of NMP. DETA + NMP + water absorbent is expected as the promising one for reducing the regeneration energy of absorbents according to volume reduction of $CO_2-rich$ phase.

• Journal of The Korean Association For Science Education
• /
• v.37 no.4
• /
• pp.539-552
• /
• 2017

The purpose of this study is to investigate the trends of model and modeling-related research in science education from 1989 to 2016 in Korea. Eighty-five (85) models and modeling-related journal articles were extracted from the KCI-listed journals and analyzed according to the criteria such as participants, research fields, research design, methods, data collection and elements of metamodeling knowledge. According to research participants, three out of four (3/4) were studied for students and the rest were for teachers. More than half of the studies for students were conducted with middle and high school students. The research fields of models and modeling-related researches in science education were comprised of earth science, chemistry, biology science, physics and science course. With regards to research design, the highest type is qualitative research and followed by hybrid research and quantitative research. According to research methods, the most numerous researches that were analyzed was the effectiveness of program, which was a developed model and modeling-related research. The analysis from the elements of the metamodeling knowledge showed most of model and modeling-related research utilized for the change of scientific concept or understanding.

• Plant Journal
• /
• v.9 no.3
• /
• pp.38-42
• /
• 2013

Submarine gas fields have focused because of the increasing fuel cost, the environmental regulations, and the safety & NIMBY problems. LNG-FPSO which is available for acid gas removal, recovery of the condensate & LPG and Liquefaction in topside process is one of high technology offshore structures. On the other hands, it is necessary to verify the pre-treatment efficiency by the ship motion and to apply to the design for LNG-FPSO. This study is to develop the pre-treatment technology for LNG-FPSO as taking account to the process efficiency by ship motion effects and the area optimization. Based on the simulation results, it founds that hybrid process shows the low circulate rate, the low heat duty and the small size of column dimensions compared to typical amine process. It will be verified the process efficiency in the various conditions by sea states as performing the 6-DOF motion test and CFD simulation.

• Journal of Wetlands Research
• /
• v.21 no.4
• /
• pp.312-320
• /
• 2019

The occurrence of cyanobacteria causes problems such as oxygen depletion and increase of organic matter in the water body due to mass prosperity and death. Each year, Algae bloom warning System is issued due to the effects of summer heat and drought. It is necessary to quantitatively characterize the occurrence of cyanobacteria for proactive green algae management in the main Nakdong river. In this study, we analyzed the major influencing factors on cyanobacteria bloom using visualization and correlation analysis. A decision tree, a machine learning method, was used to quantitatively analyze the conditions of cyanobacteria according to the influence factors. In all the weirs, meteorological factors, temperature and SPI drought index, were significantly correlated with cyanobacterial cell number. Increasing the number of days of heat wave and drought block the mixing of water in the water body and the stratification phenomenon to promote the development of cyanobacteria. In the long term, it is necessary to proactively manage cyanobacteria considering the meteorological impacts.

• Korean Journal of Food Science and Technology
• /
• v.24 no.2
• /
• pp.149-153
• /
• 1992

Antioxidative effects of crude ethanol extract of the Rhus javanica L. and its fractionates with various synergists on the oxidation of palm oil, lard and soybean oil were compared with induction period(IP) using a Rancimat test. Addition of 200 ppm of the crude extract with phosphoric acid to palm oil extended IP 2.89 times as much as that of control and ethyl acetate fractionate extended IP 4.18 times at the same condition. To lard, 600 ppm of chloroform fraction with 200 ppm of ${\delta}-Tocopherol$ extended IP 13.42 times as much as that of control. 200 ppm of each fraction with various synergists were added to palm oil and lard, and oxidative stability of the oils were monitored by measuring POV, AV, and TBA value. The POV of palm oil containing 200 ppm of ethyl acetate and chloroform fraction with 200 ppm of phosphoric acid after 27 days storage at $60^{\circ}C$ were 8.9 meq/kg and 9.4 meq/kg respectively while the POV of control was 98.3 meq/kg at the same condition. AV and TBA value were also lower than that of control. The POV value of lard containing same amount of ethyl acetate and chloroform fraction with ${\delta}-Tocopherol$ after 12 day storage at $60^{\circ}C$ were 20.0meq/kg and 10.7 meq/kg respectively while the POV of control was 161.1 meq/kg at the same condition. AV and TBA value were also lower than that of control.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.12
• /
• pp.57-62
• /
• 2010

In this study, the effect of different silt contents on the shear characteristics of silty sands was evaluated. Two series of triaxial compression tests were performed on the cylindrical specimens of compacted Nakdong river sand with 10% and 30% silt contents under unconsolidated undrained condition. All identical specimens were prepared to compact with same initial water content for five layers and saturated using control panel and then sheared under initial effective confining pressure, 100 to 400kPa. All specimens exhibited a strain softening tendency after failure in stress-strain curves and deviator stresses of specimens with 10% silt content were greater than those of specimens with 30% silt content. Pore water pressures of specimens with 10% silt content were observed negative(i.e. swelling) due to increasing void ratio after failure but those of specimens with 30% silt content were shown only positive. The behavior of compacted cylindrical specimens with low silt content was more dilative than that of high silt content. Peak deviator stresses decreased as increasing silt content and peak pore water pressures increased as increasing silt content.