• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.559-563
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• 2014

It is well known that $CO_2$ can be dissolved easily in imidazolium-based room temperature ionic liquids (RTILs). Because of the high $CO_2$ solubility in RTILs, membranes containing RTILs can separate easily gas mixtures such as $CO_2/N_2$ and $CO_2/CH_4$. In this study, we prepared poly(vinylidene fluoride)-hexafluoropropyl copolymer (PVDF-HFP) gel membranes with several RTILs and measured permeabilities of several gases. When the anion of ionic liquids was tetrafluoroborate($BF{_4}^-$), both $CO_2$ permeability and selectivities decreased as the carbon number of the cation increased. When the cation of ionic liquids was 1-ethyl-3-methylimidazolium[emim], $CO_2$ permeability of gel membranes containing bis(trifluoromethane) sulfoneimide($Tf_2N^-$) anion was double compared to those containing tetrafluoroborate($BF{_4}^-$) anion. However, $CO_2/N_2$ and $CO_2/CH_4$ selectivities of the $Tf_2N^-$ case were decreased, whereas the $H_2$ selectivity was almost the same for two cases.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1067-1071
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• 1997

A new type of gripper for micrometer-size objects is developed using piezoelectric multi-layer benders. It is composed of three chopsticks, two of which are designed to grip micro-objects. The third one is reserved for helping the two when objects are released from the chopsticks. It is well known that a micro object is much easier to grasp than to release it after holding it. The electrostatic force between the chopsticks and an object is believed to be the main cause of adhesion in a dry environment. The surface tension becomes very important when liquids are present or in a liquid. The third auxiliary chopsticks is introduced to solve there surface effects. All the three chopsticks are made of tungsten wires with sharpened ends by etching. When grasping microparts, the two chopsticks are utilized, and, when releasing them anywhere the parts are located, the third one reduces the electrostatic force between the objects and the chopstick may be to help the other two chopsticks to hold an objects in a desired orientation. We constructed the three chopstick gripoer for micro objects and test their function by holding and releasing an object of a diameter of 100 micrometers. We make use of open loop voltage control. The bender displacement resolution is sub-micrometer. The gripping forces, about tens of mN are obtained. The experiment shows that the third auxiliary chopstick functions effectively.

• Journal of the Korean Electrochemical Society
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• v.14 no.4
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• pp.201-207
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• 2011

Supercapacitor has been studied actively as one of the most promising electrochemical energy storage system for a wide range of applications. To increase the energy density of supercapacitor, the introduction of ionic liquids is required. In this study, two types of EMI-$BF_4$ based on quaternary imidazolium salt were prepared with quaternary reaction and anion exchange. The structural characterization and thermal stability were analyzed by nuclear magnetic resonance($^1H$-NMR) and thermogravimetric analysis(TGA), respectively. Thermal stability of the EMI-$BF_4$ using TGA confirmed that, after heat treatment, the decomposition temperature of EMI-$BF_4$ was increased. Supercapacitors were fabricated with synthesized and commercial ionic liquids, and charge/discharge characteristics were also investigated. The capacity of supercapacitor, for synthesized and commercial EMI-$BF_4$ were determined to be 0.067 F and 0.073 F respectively, by means of charge/discharge test.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3276-3286
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• 1994

In most direct contact liquid-liquid heat exchangers, oil or hydrocarbon with a density less than water is normally used as dispersed working fluid. The main difficulty that arises with this arrangement lies in the control of the interface at the top of the column. When it is connected with a solar collector which uses water as its working fluid, the main difficulties arise from the fact that the water can be frozen during winter time. In order to solve these problems and to demonstrate the technical feasibility of a direct contact liquid-liquid heat exchanger, liquids heavier than water with low freezing temperature has been utilized as dispersed phase liquids in a small laboratory scale model made of pyrex glass. In the present investigation, dimethyl phthalate(C/sub 6/H/sub 4/)COOCH/sub 3/)/sub 2/) and diethyl phthalate (C/sub 6/H/sub 4/(CO/sub 2/C/sub 2/H/sub 5/)/sub 2/) are utilized as heavy dispersed phase working fluids. The results of the present investigation the technical in the utilization of heavier dispersed working liquid in the spray-column liquid-liquid heat exchanger for a solar system. The overall average temperature difference along the column is found to be almost half of the initial temperature difference between the dispersed and the continuous phase. Despite the fact that the two phthalates tested in the experiment differ significantly in some of their physical properties, the volumetric heat transfer coefficients in terms of dispersed fluid superficial velocities were found to be similar for both phthalates tested.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.716-722
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• 2003

This study determined the optimum dosage for coagulation reactions of red tide organisms (RTO) using a combination of ignited oyster shell powder (10sp) and loess and examined the electrokinetic and rheological characteristics of their flocs. Two kinds of RTO, Cylindrotheca closterium and Skeletonema costatum, were sampled in Masan Bay and cultured in the laboratory. Coagulation experiments were conducted using various concentrations of IOSP, loess, IOSP+1oess, RTO, and a jar tester RTO cell numbers were counted for both the supernatant and RTO culture solution. The removal rates increased rapidly with increasing IOSP concentrations up to 50 mg/L and loess concentrations up to 800 mg/L. A removal rate of $100\%$ was reached at 400 mg/L of IOSP and 6,400 mg/L of loess. The highest increment $(16.7\%)$ of the rates of coagulation reaction occurred using both IOSP and loess (50+200 mg/L) in comparison with IOSP alone. The rate of coagulation reaction using both IOSP and loess (50+200 mg/L), $90.6\%,$ was similar to employing either IOSP of 150 mg/L or loess of 3,200 mg/L. All of the coagulation liquids for RTO, IOSP (200 mg/L), loess (200 ma/L), and IOSP+1oess (200+200 mg/L) revealed non-Newtonian fluid properties and therefore their shear rate vs. shear stress curves were non-linear. The coagulation liquids revealed elastic body properties at a lower shear rate increasing in the following order: RTO, IOSP (200 mg/L), loess (200 mg/L), and IOSP+1oess (200+200 mg/L. IOSP+1oess (200+200 mg/L) especially demonstrated plastic flow properties at a lower shear rate.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.286-290
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• 2007

The esterification efficiency of several ionic liquids has been investigated to determine the feasibility for the conversion of free fatty acids to alkylester. Five ionic liquid catalysts having strong acidity, BPC[$AlCl_3$], BMIM[$Bf_4$], BMIM[$Pf_6$], EMIM[$Ntf_2$], BMIM[Otf], have been employed in this work. BPC[$AlCl_3$] has the highest esterification efficiency among the ionic liquid catalysts. Over 90% conversion efficiency has been achieved in the esterification of the simulated used cooking oil by BPC[$AlCl_3$] with two hours reaction time. Since BPC[$AlCl_3$] has several advantages such as high esterification activity, ease of separation from reaction mixture and reusability after treatment procedure, it will be a promising catalyst for the conversion of free fatty acids to esters in waste fats.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2097-2102
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• 2011

Discharge analysis technique for dielectric liquid was presented by using the Finite Element Analysis (FEA) under a lightning impulse incorporating two-phase flow phenomena which described gas and liquid phases in discharge space. Until now, the response of step voltage has been extensively explored, but that of lightning impulse voltage was rarely viewed in the literature. We, therefore, developed an analyzing technique for dielectric liquid in a tip-sphere electrode stressed by a high electric field. To capture the bubble phase, the Heaviside function was introduced mathematically and the material functions for the ionization, dissociation, recombination, and attachment were defined in liquid and bubble, respectively. By using this numerical setup, the molecular dissociation and ionization mechanisms were tested under low and high electric fields resulted from the lightning impulse voltage of 1.2/50 ${\mu}s$. To verify our numerical results, the velocity of electric field wave was measured and compared to the previous experimental results which can be viewed in many papers. Those results had good agreement with each other.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1251-1251
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• 2001

The routine analysis of milk chemical components is of major importance both for the management of animals in dairy farms and for quality control in dairy industries. NIRS technology is an analytical technique which greatly simplifies this routine. One of the most critical aspects in NIRS analysis of milk is sample preparation and analysis modes which should be fast and straightforward. An important difficulty when obtaining NIR spectra of milk is the high water content (80 to 90%) of this product, since water absorbs most of the infrared radiation, and, therefore, limits the accuracy of calibrating for other constituents. To avoid this problem, the DESIR system was set up. Other ways of radiation-sample interaction adapted for liquids or semi-liquids exist, which are practically instantaneous and with limited or null necessity of sample preparation: Transmission and Folded Transmission or Transflectance. The objective of the present work is to compare the precision and accuracy of milk calibration equations in two analysis modes: Reflectance (dry milk) and Folded Transmission (liquid milk). A FOSS-NIR Systems 6500 I spectrophotometer (400-2500 nm) provided with a spinning module was used. Two NIR spectroscopic methods for milk analysis were compared: a) folded transmission: liquid milk samples in a 0.1 pathlength sample cell (ref. IH-0345) and b) reflectance: dried milk samples in glass fibre filters placed in a standard ring cell. A set of 101 milk samples was used to develop the calibration equations, for the two NIR analysis modes, to predict casein, protein, fat and dry matter contents, and 48 milk samples to predict Somatic Cell Count (SCC). The calibrations obtained for protein, fat and dry matter have an excellent quantitative prediction power, since they present $r^2$ values higher than 0.9. The $r^2$ values are slightly lower for casein and SCC (0.88 and 0.89 respectively), but they still are sufficiently high. The accuracy of casein, protein and SCC equations is not affected by the analysis modes, since their ETVC values are very similar in reflectance and folded transmission (0.19% vs 0.21%; 0.16% vs 0.19% and 55.57% vs 53.11% respectively), Lower SECV values were obtained for the prediction of fat and dry matter with the folded transmission equations (0.14% and 0.25% respectively) compared to the results with the reflectance ones (0.43% and 0.34% respectively). In terms of accuracy and speed of analytical response, NIRS analysis of liquid milk is recommended (folded transmission), since the drying procedure takes 24 hours. However, both analysis modes offer satisfactory results.

• Journal of the Korean Society of Visualization
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• v.9 no.4
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• pp.69-73
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• 2011

Butterflies have been known to suck viscous liquids through a long, cylindrical proboscis using the large pressure difference formulated by the cyclic expansion and contraction of a muscular pump located inside their head. However, there are few studies on the liquid-feeding phenomena in a live butterfly, because it is hard to observe the internal morphological structures under in vivo condition. In this study, the dynamic motion of the pump system in a butterfly was in vivo visualized using synchrotron X-ray micro-imaging technique to analyze the liquid-feeding mechanism. The period of the liquid-feeding process is about 0.3sec. The expansion stage is about two times larger than the contraction stage in one cycle. The cyclic variation of pump volume generate large negative suction pressure and the pressure difference inside the long proboscis of a butterfly is estimated to be larger than 1atm.

• Journal of the Korean Chemical Society
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• v.11 no.3
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• pp.105-110
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• 1967

The transient state theory of significant liquid structure is applied to nitrous oxide and nitrogen tetroxide. The partition functions for the two liquids are derived according to the transient state theory. The various thermodynamic properties; such as, molar volumes, vapor pressures, entropies of vaporization, and critical point properties agree well with the experimental values.