• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.869-876
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• 1996

Purification of 2,6-dimethylnaphthalene(2,6-DMNA) from the distillate containing a mixture of dimethylnaphthalene(DMNA) isomers of very high concentration was investigated by crystallization-recrystallization combination as a after-treatment for separation and purification of 2,6-DMNA in the light cycle oil(LCO). The separation of individual isomers of DMNA was studied by crystallization with the distillate as a feed. 2,6-DMNA, 2,7-dimethylnaphthalene(2,7-DMNA) and 2,3-dimethylnaphthalene(2,3-DMNA) were concentrated to crystal, and it was fould that separation between a group of 2,6-, 2,7-, 2,3-DMNA isomers and a group of the other DMNA isomers was possible. However, it was not possible to separate 2,6-, 2,7- and 2,3-DMNA from one another. To select the most suitable recrystallization solvent for purification of 2,6-DMNA, several conventional solvents, which have been employed commercially as recrystallization solvents for high purity performance, were tested, through measurement of solubility of 2,6- and 2,7-DMNA. The solvent used were hexane, iso-propyl ether, ethyl acetate and ethanol. From the solubility results for 2,6- and 2,7-DMNA, ethanol seemed to be the most suitable solvent for purification of 2,6-DMNA. Finally, with crystal recovered by crystallization as a feed and ethanol as a solvent, recrystallization experiments were conducted under various conditions. Purification of 2,6-DMNA was easily done with increasing operating temperature and solvent to feed ratio. These results show that the crystallization-recrystallization combination is an effective one for separation of individual isomers of DMNA.

• Membrane Journal
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• v.24 no.1
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• pp.1-9
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• 2014

In this study, four soluble homo- and co-polyimides using 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOCDA) and 4,4'-diaminodiphenyl ether (ODA) monomers were synthesized to develop the gas separation membrane with good $CO_2/CH_4$ separation properties. To prepare the copolyimides, 20 mol% of three dianhydrides - (4,4'-(hexafluoroisoproplidene)diphthalic anhydride (6FDA), 4,4'-biphthalic anhydride (BPDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) - were added in DOCDA-ODA monomer mixture, respectively. All the synthesized homo- and co-polyimides were characterized by FT-IR. Their thermal properties were analyzed with differential scanning calorimeter (DSC). Dense membranes were prepared from these copolyimides to check their gas permeation properties for $CO_2$ and $CH_4$ gases using a time-lag method. The permeation testing results are as follows; DOCDA/ODA homopolymer showed 1.71 barrer of $CO_2$ permeability and 74.35 of $CO_2/CH_4$ selectivity. The three polyimide copolymers (DOCDA/6FDA-ODA, DOCDA/BPDA-ODA, DOCDA/BTDA-ODA) showed lower $CO_2/CH_4$ selectivities and higher $CO_2$ permeabilities than the homopolymer (DOCDA-ODA). DOCDA/6FDA-ODA showed twice times higher $CO_2$ permeabilities without severe $CO_2/CH_4$ selectivity loss than the DOCDA-ODA.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.15 no.1
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• pp.91-100
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• 2004

Objectives：The effects of repeated maternal separation on the expression of glucocorticoid receptor (GR) and cyclooxygenase-2(COX-2) in the hippocampus of rat pups at preweanling stage were evaluated. Methods：The experimental, Repeated Maternal Separation group(N=4) was separated from the mother for four hours a day over a period of ten days beginning with postnatal day 4. The Control group(N=4), on the other hand, did not separated from the mother at all. GR and COX-2 expression in the hippocampus was examined by immunohistochemistry on postnatal day 14. Results：It was determined that the number of GR-immunopositive cells in the dentate gyrus of the hippocampus was significantly increased in the Repeated Maternal Separation group. The numbers of COX-2-immunopositive cells in the CA1 and CA3 were also significantly higher in the Repeated Maternal Separation group. Conclusion：These results suggest that maternal separation may be a significant developmental stress that induces GR and COX-2 expression in the hippocampus of developing pups.

• Journal of Korean Neurosurgical Society
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• v.53 no.3
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• pp.145-149
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• 2013

Objective : We analyzed the clinical and radiologic features of posterior apophyseal ring separation (PARS) with lumbar disc herniation and suggest the proper management options according to the PARS characteristics. Methods : We reviewed case series of patients with PARS who underwent surgery of lumbar disc herniation. Preoperative symptoms, neurologic status, Body Mass Index, preoperative and postoperative Visual Analogue Scale (VAS) and Korean-Oswestry Disability Index (K-ODI) scores, operation types were obtained. PARS size, locations, the degree of resection were assessed. Results : PARS was diagnosed in 109 (7.5%) patients among 1448 patients given surgical treatment for single level lumbar disc herniation. There were 55 (50.5%) small PARS and 54 (49.5%) large PARS. Among the large PARS group, 15 (27.8%) had lower endplate PARS of upper vertebra at the level of disc herniation. Thirty-nine (72.2%) were upper endplate PARS of lower vertebra. Among the group with upper endplate PARS of lower vertebra, unresected PARS was diagnosed in 12 (30.8%) cases and resected PARS was diagnosed in 27 (69.2%) cases. VAS and K-ODI scores changes were $3.6{\pm}2.9$ and $5.4{\pm}6.4$ in the unresected PARS group, $5.8{\pm}2.1$ and $11.3{\pm}7.1$ in the resected PARS group. The group with upper endplate PARS of lower vertebra showed significant difference of VAS (p=0.01) and K-ODI (p=0.013) score changes between unresected and resected PARS groups. Conclusion : The large PARS of upper endplate in lower vertebra should be removed during the surgery of lumbar disc herniation. High level or bilateral side of PARS should be widely decompressed and arthrodesis procedures are necessary if there is a possibility of secondary instability.

• Clinical and Experimental Reproductive Medicine
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• v.15 no.2
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• pp.149-155
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• 1988

To increase fertilization rate in vitro, separation of viable spermatozoa from the seminal plasma and its other components may be a useful procedure. Ejaculates from healthy men, whose semen analysis findings were normal in 19, and abnormal in 10, were filtered using the glass-wool filtration technique to yield a concentrated, viable sperm samples for IVF, and the usefulness and safety of this method were evaluated. The recovery rate of motile sperm in abnormal groups was 46.2% and 54.5% in normal group. The % motility was increased significantly compared with original sample after filtration, and the grade motility was improved, too. The sperm population with normal morphology was also increased significantly in both group. Using transmission electron microscopy, the ultrastructural integrity of acrosomal segment was examined in order to evaluate the potentially hazardous effect of glass-wool filtration to sperm head, however, sperm population with normal ultrastructure was increased compared with that of original ejaculate after separation. The filtered sperm was then processed for IVF, as the fertilizing capacity is the ultimate parameter of the sperm function. In abnormal group, the fertilization rate(41.5 %) and the ET rate per stimulated cycle were much lower than that of mormal group(69.6%). However, the cleavage rate and the number of embryos transfered per ET cycle were comparable with those of nomal group. The results suggest that the glass-wool filtration of sperm, particularly in oligo-asthenozoospsrmia, may be useful and safe method in the preparation of sperm for IVF.

• Journal of Korean Academy of Nursing
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• v.3 no.3
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• pp.97-110
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• 1973

The goal of modern nursing is to provide comprehensive nursing care to patients. If comprehensive nursing care to children (within the hospital setting) is to be provided, consideration of the stage of growth and development of the child is especially important. From clinical observation, it appeared that nurses often disregarded individual requirements of children in giving nursing care. Therefore, the purpose of this study is to show that comprehensive nursing care which is based on an understanding of the growth and development of the child contributes to both the child and the mother's adaptability to the child's hospitalization. Method: Sixty children, three to three year of age, hospitalized at the Yonsei University Pediatric Ward ware studied. From April 1, 1973 to May 5, 1973, children admitted to the hospital were assigned to either an experimental or a compare groups. There were 30 children in each group. The sex and age of the children in each group was similar. In both groups were more male than female children. In the experimental group, each mother stayed with hot child continuously during his hospitalization. In the compare groups, the mother or some other member of the family stayed with the child. Each day on the child's admission the investigator visited the ward from 1-2 P.M. to 9-10 P.M., in order to provide comprehensive care for the experimental -group. The assistance given the nurses by the investigator was in the form of conferences regarding care and in giving direct care to the child and his mother. The compare group of children received nursing care as usually provided by the hospital. The instruments used to obtain the data for analysis were as follows: 1. The fear and anxiety reaction of the child was recorded by observation of the investigator for four areas: 1) separation from parent and relatives 2) reaction to Doctor and Nurse with white gowns 3) reaction to nursing care 4) reaction to injection and tests, etc. 2. Regression in area of eating, sleeping, and elimination were recorded by the investigator by questioning the mother and by observation. 3. Adaptability to the hospitalization was recorded by direct questioning of the children for areas of emotional and social adjustment. For children older than 3 years of age or children not seriously ill, using the simple I. Q. test this was possible for only 35 of the total 60 children. Result: 1. 55 percents of the total 60 children had been prepared by their parents for hospitalization. The children who had received prior preparation accepted hospitalization more readily than those who had received no preparation. (χ²=4.6 Ρ<0.05) 2. On admission 31.7 percent of the children expressed verbal fear of their discase or treatment. 25 percent felt that the disease was due to their mistake. 3. There was a significant difference in the reaction of the child to separation from the parent or relatives between the two groups. The experimental groups showed less anxiety due to separation than the compare group. (χ²=4.34 Ρ<0.05) In both groups there was less anxiety due to separation among school age (6-12 years) children than among preschool age (3-5 years) children. (χ²=9.22 Ρ<0.05) 4. More than half of the children in both groups reacted with fear and avoidance to doctor and/or nurses wearing white gowns. (χ²=0.06 Ρ<0.05) 5. The experimental group reacted more favorably to nursing in general than the compare group. (χ²=4.8 Ρ<0.05) 6. There was no difference in the fear and refused reaction to special tests and/or such as X-rays and injections, etc. between the groups. (χ²=3.77 Ρ<0.05) 7. More children in the compare group showed regressive tendencies in eating, sleeping, and elimination habits than in experimental groups. (χ²=2.3 Ρ<0.05 χ²=3.88 Ρ<0.05 χ²=4.9 Ρ<0.05) 8. There was a significant difference in the adaptability to hospitalization between the two groups. The experimental groups adapted more readily. (χ²=2.02 Ρ<0.05) 9. For children who had higher I.Q. s the adaptability to hospitalization was better regardless of the group. (χ²=5.03 Ρ<0.05) However, because of the small number of cases (60), this finding cannot be extrapolated without further verification. The date demonstrates that there was a greater adaptability to hospitalization by the child when comprehensive nursing care was given. By planning care and applying knowledge of growth and development to meet, nurses are in a position to prevent some of the psychological trauma associated with hospitalization.

• Membrane Journal
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• v.19 no.1
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• pp.54-62
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• 2009

Pervaporation membrane for butanol separation was prepared by hybrid process. Plasma treatment of commercial poly(dimethylsiloxane) (PDMS) membrane was attempted and combination of plasma treatment and PDMS solution coating on polysulfone, poly(ether imide) supports were also performed. Plasma treatment of PDMS membrane with hexane and silane group compounds was performed to increase the hydrophobicity of the surface, which enhanced the separation factor upto 12.5 at the expense of flux decrease down to $1.15kg/m^2{\cdot}hr$. Contact angle and relative sorption ratio were also related with hydrophobicity of the memrbane. Increase of PDMS prepolymer composition resulted in dense structure of coating layer with better separation factor. Effects of sequence of PDMS coating vs. plasma treatment were examined. It was found that plasma treatment with butanol and n-hexane plasma followed by PDMS coating showed better performance and vice versa for plasma treatment with hexamethyldisilane and hexamethyldisilazane.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.76-80
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• 2005

It was evaluated whether magnetic beads able to add the functionality of environment purification can be employed in processing soil pollutants. In this study, the micro scale magnetic beads containing carboxyl groups were mixed with water and the soil $(<0.025{\cal}mm) filtered through a sieve, and then it was agitated before isolating the magnetic substances by the use of outer magnetic force. The factors considered at this step were the ratio of soil to magnetic beads, ratio of soil to water, size of the tube where the reaction occur, and intensity of the magnetic force. From the separation experiment between soil and magnetic beads, it was concluded that the magnetic beads and water quantity have an impact on the degree of separation, yet the size of the tube and magnetic force does not have a considerable effect upon that in this small-scaled experiment. Through this experiment, the reaction conditions were optimized to achieve $90\~100\%$ of separation. Therefore, it was concluded that when the functionalized magnetic beads is introduced to environmental processing, it is able to be adopted to the soil processing as well as the water processing.

• Resources Recycling
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• v.18 no.2
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• pp.30-38
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• 2009

In this research, we studied the scale-up triboelectrostatic process for separation of PVC from higher gravity fraction of plastic wastes produced from wet gravity separation process. High density polyethylene (HDPE) was found to be the most effective materials for a tribo-charger in the separation of plastic tailings. In a commercial scale triboelelctrostatic separator unit, using the HDPE pipe-line charger, a grade of 99.1% with PET, PS and others and a recovery of 86% was obtained under optimum conditions at over 250 kV/m electric field, a splitter position of -8 cm from the center, and less than 40% relative humidity. The developed unit can process the plastic wastes at a 300 kg/h, and the product can be utilized as RPF or RDF of over grade 2.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.1
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• pp.57-66
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• 2012

The purpose of this study was to evaluate the relation between intentionally induced internal stress and cyclic fatigue failure of ProTaper Universal. ProTaper Universal (Dentsply Maillefer) S1, S2, F1, F2, F3, F4 and F5 (25 mm length) were used in this study. To give the internal stress, the ProTaper Universal were put into the .02 taper Endo-Training-Bloc (Dentsply Maillefer) until auto-stop by torque controlled motor. The rotation speed was 300 rpm and torque value was 1.0 Ncm. ProTaper Universal were grouped by the induced number of internal stress and randomly distributed among one control group and three experimental groups (n=10). The four groups were Stress 0 (control), Stress 1, Stress 2 and Stress 3. These instruments were rotated until separation. For cyclic fatigue measurement, inclined plane was used and time for separation was recorded. It was statistically analyzed using two-way ANOVA and Duncan post-hoc test at 95% confidential level. In all ProTaper Universal, there was statistically significant decrease on time for separation in Stress 3. In F2 and F3, there were statistically significant difference between control group and all experimental groups. And in F4 and F5, Stress 2 and 3 groups showed significantly lower cyclic fatigue resistance from Stress 0 group. In the limitation of this study, cyclic fatigue failure of ProTaper Universal is influenced by accumulated internal stress.