• Journal of Korean Ophthalmic Optics Society
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• v.17 no.2
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• pp.135-141
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• 2012

Purpose: Polymerization of HEMA(2-hydroxyethyl methacrylate) which can be used in the soft contact lens has been performed by using electron beam(EB) irradiation, and examined the best condition for the polymerization. Comparing the physical properties of the contact lenses to the one fabricated by thermal polymerization method, we check the use possibility of the EB irradiation to the fabrication of the soft contact lens. Methods: We investigated the degree of polymerization of the HEMA according to the composition of the monomer, the additive ratio and the dose of electron beam (0~120 kGy). The degree of polymerization was measured depending on the EB dose to research the best synthetic condition under the EB irradiation. The physical properties of the contact lens such as water content(%), oxygen transmissibility(Dk/t) and optical transmittance were analysed by using the FT-IR results with comparing the two different polymerization method (thermal and electron beam polymerization) with same additive ratio. Results: When the dose of electron beam was above 100 kGy, the degree of polymerization of HEMA was above 99% with regardless using cross-linker and initiator. The water content of the lens fabricated by EB method showed 10% higher than the one by the thermal method which was 40%. The lens fabricated by EB method also showed higher oxygen transmissibility(Dk/t) as same with the water content, and showed twice higher value in the lens fabricated by pure HEMA. According to the FT-IR results, hydrophilic property of the lens fabricated by EB method was increased due to increasing the intermolecular hydrogen bonding. It showed above 90% optical transmittance in the visible range of wavelength on the contact lenses fabricated by the both of two different polymerization method. Conclusions: The polymerization of HEMA without cross-linker and initiator was successful above 100 kGy of EB irradiation. Moreover the lens fabricated from the polymer synthesized by pure HEMA with 100 kGy of EB showed the highest water content and oxygen transmissibility. Therefore EB irradiation is another possible method to synthesize the polymer which can be used for the soft contact lens.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.741-755
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• 1995

Currently titanium is the material of choice for implants because of its biological acceptance. This high degree of biocompatibility is thought to result, in part, from the protective and stable oxide layer that presumably aids in the bonding of the extracellular matrix at the implant-tissue interface. Endosseous dental implants are interfaced with bone, connective tissue, and epithelium when implanted into the jaw bone. The soft tissue interface including connective tissue and epithelium is one of the most critical factors in the determination of implant maintenance and prognosis. For maintenance of failing or failed implants, it is essential to treat the implant fixture surface to remove bacterial endotoxins and make a surface tolerated by surrounding soft and hard tissues. In this study, the effect of mechanical treatment on titanium plasma sprayed implant on adhesiveness and proliferation of human gingival fibroblasts and changed surface characteristics were studied. titanium plasma sprayed discs manufactured by Friedrichsfeld company were treated with loaw speed stone bur, a rubber point and a jetpolisher. Its surface components were analyzed with Energy dispersive X-ray spectroscopy to evaluate whether the surface characteristics were altered or not. To observe the spreading pattern of the human gingival fibroblasts which attached to the all specimens author used the scanning electron microscope. The results were as follows : Pure titanium and plasma sprayed titanium, stone polished titanium showed titanium peak and small amout of aluminum, so there was no alteration on surface characteristics. Under the scanning electron microscopic examination in the initial attachment of human gingival fibroblast, there was a slight enhancement in pure titanium, stone polished titanium than plasma sprayed titanium. After 6 hours, the pure titanium and stone polished titanium showed human gingival fibroblasts were elongated and connected with numerous processes. Human gingival fibroblasts were more intimately attached on the pure titanium discs than on the other discs. The human gingival fibroblasts attached on the plasma sprayed titanium by thin and elongated processes. After 24 hours, the human gingival fibroblasts connected with each other via numerous processes and compeletly covered the pure titanium and stone polshed titanium discs. Human gingival fibroblasts had multiple point contacts with more long and thin lamellopodia and showed a little bare surface on plasma sprayed titanium discs.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.2
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• pp.321-331
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• 2005

The purpose of this study was to compare the effectiveness of mechanical and acid treatment on enamel surfaces for the retention of pit and fissure sealants and evaluate the presence of a prismless layer. The etch pattern produced on enamel from immature and mature premolar teeth extracted with varying period of acid etching using 37% phosphoric acid was examined using a scanning electron microscope(SEM). The composition of each groups was evaluated using an energy dispersive x-ray(EDX) spectroscopy. The result of present study can be summarized as follows: 1. Prismless layer was commonly observed on the fissure enamel in young and mature premolar. 2. There were no differences in micro-structure and etching pattern on fissure enamel between the young and the mature premolar. 3. The most effective etching pattern for retention of pit and fissure sealant was observed in 60 seconds of etching time and no apparent difference of etching pattern was found among 15, 30, and 45 seconds of etching time which showed non-retentive etching patterns. 4. The etching pattern obtained by grinding enamel surface with bur followed by 60 seconds of etching was similar to that of 60 seconds of etching without any pretreatment of fissure surface. 5. Type 2 etching pattern was commonly found on fissure enamel in both young and mature premolar. 6. The calcium content and P/Ca ratio in fissure enamel between the young and the mature premolar were significantly different(P<0.05). But content of calcium, phosphate and P/Ca ratio on various regions of fissure enamel in both young and mature premolar did not showed any difference. Based on these results, prismless layer may negatively influence the retention of pit and fissure sealants. Therefore, the mechanical removal of the prismless layer by grinding prior to etching or by prolonged etching time of enamel within the fissure system should result in an improved bonding of a pit and fissure sealant.

• Child Health Nursing Research
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• v.4 no.1
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• pp.60-75
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• 1998

The parents have much expectation upon the pregnancy and child birth, and in most cases, they expect the healthy parturient child. However, we can be placed on the high-risk conditions which have the physical, social and immature infant, due to the unexpected results, among the new-born. Accordingly, these high-risk newborn and premature infants will be mostly in NICU, which the concentrated medical treatment can be given, upon their conditions. After their birth and during these periods, they will be divided from the parents, and the nurse will accomplish the bringing-up activities which they can take care of the infant, expected by the parents after their birth. The hospitalization of high-risk newborn including these premature infants is the shocking experience to the parents of family, and thus they can feel the fear and uneasiness, and these reactions of parents are troubled in the behavior at the usual days, and cause the disorder and spiritless status, and these results break the supporting ability of parents, and cause the obstruction. Also, the unavoidable division between the parents and the children as like hospitalization of children can make the parents to feel the alienation emotionally, and this causes the results which the pride on the bringing-up ability of baby gets to be lost. These problems can cause the difficulties on the bonding or the parenting in the further days, and can be related to the neglect and abuse of children. Also, it is gradually increased to study and report which the emotional division by the physical division between the mother and the baby obstructs the normal affection course between the parent and the infant. The stress caused by the birth and the hospitalization of high-risk newborn, as like this, is important in the points which it can uncertainly affect the potential energy for the relationship of parent-child who are finally healthy. Accordingly, the significance and purpose of this study are to understand the contents and degree of stress which the parents of high-risk newborn including the immature child can be experienced from the hospitalization of ICU for their new borns, and thus to offer the basic program to the nursing intervention program for these. The subject of this study is the mother of newborn in NICU of 10 General Hospitals located at the 3one of Pusan, Korea from September 1997 to October 1997, and thus makes the subject of 95 person of parents who agreed to take part in the study and it is descriptive study related to the stress of mother having the newborn in NICU. The method is based on the preceding study related to the stress of mother having the experience of child hospitalization and chronic disease child, and then acquires the advice of specialists group as like 5 nursing professors, and then is amended and supplemented. Total number of questions is 43 items and consists of 5 factors as like medical treatment &nursing procedures, disease status & prognosis, role of parents, communication & inter-personal relationships, hospital environment, and is 5 point Likert Scale. The reliability of this study method is very highly shown to be Cronbach α=0.95. The collected data is analysed as Average, Frequency, Standard Deviation, T-test, ANOVA, Pearson Correlation Coefficient, Duncan multifulrange test by use of SPSS /PC (V7.5). The results of this study is summarized as under. 1. Every characteristics of subject is which the party of mother is 28.70age(±7.48) in the average ages, 51% in the high-school graduate, 38.5% in the christianity, total monthly income is 212.55 thousand won(±1.971), 74.5% in the housewife, 72.9% in the parents and children together living and the number of children to be 1.48person(± 0.6) in average, the recognition on the prognosis of baby is 74.0% in 'Don't know', the relationship with the husband after the hospitalization of babyis 37.3% in 'More Intimate', the relationship with the family of husband to be 48% in 'No-change', and the degree which is consulted with the husband about the baby is 55% in 'very frequently' and the visiting number per week is 4.59(±1.63) in average and the accompanying person in the time of visiting is which the number of husband is 56.3% and thus is the highest. The characteristics of baby is which the age is 21.88days(±16.47) after the birth in average, the sex to be 50 person in the female 52.1% and the order of birth to be 54.2% in the first chid, and the weight in the birth to be 2770gm(±610) and the height in the birth to be 46.26cm(±7.62) in aver age. The medical diagnosis is 37.5% in the premature infant, the career of hospitalization is 96.9% in 'None', and the operation plan is 90.6% in 'None' and the execution of operation is 88% in 'None' and the nursing of incubator is 55.2% in 'Yes', and the method of feeding is 50.5% in 'Oral' and the contents of feeding is 46.9% in the 'Milk'. 2. The total stress degree of subject is almost highly shown to be as 3.36(±0.86). If it is compared upon each cause, 'stress on disease status & prognosis' is highest 3.79(±1.28), and it is in the order of 'stress on medical treatment & nursing procedures' 3.70(±0.93), 'stress on hospital environment' 3.14(±0.86), 'stress on role of parents' 3.18(±0.92) and 'stress on communication & inter personal relationship' 2.62(± 0.77) 3. As the results of checking the notworthiness of stress degree upon each variable of subject, the variable showing the noted difference was the birth weight(γ=-0.16, P=0.04), birth height(γ=-0.23, P=0.03), nursing in the incubator(F=8.93, P=0.04), feed method(F=2.94, P=0.04). That is to say, it is shown which the smaller the birth weight is, the higher the stress degree of mother is noteworthily. Also, the smaller the birth height baby is, the higher the stress of mother is. In the incubator, it os shown which the mother whose baby is nursing in the incubator is higher in the stress degree than other mothers. Upon the feeding method of baby, that is to say, TPNis the highest, and it is shown in the order of NPO, Tube feeding, and P.O. feeding. When we review the above-mentioned results, as the status is serious, it is thought which we include the supporting nursing for coping with the stress of parents in the setting-up od nursing plan for the baby in the NICU.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.349-356
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• 2006

We have investigated adsorption and desorption properties of CO adsorption on silica supported Ru/Ni alloys at various Ru/Ni mole content ratio as well as CO partial pressures using Fourier transform infrared spectrometer (FT-IR). For Ru-$SiO_{2}$ sample, four bands were observed at $2080.0cm^{-1}$, $2021.0{\sim}2030.7cm^{-1}$, $1778.9{\sim}1799.3cm^{-1}$, $1623.8cm^{-1}$ on adsorption and three bands were observed at $2138.7cm^{-1}$, $2069.3cm^{-1}$, $1988.3{\sim}2030.7cm^{-1}$ on vacumn desorption. For Ni-$SiO_{2}$ sample, four bands were observed at $2057.7cm^{-1}$, $2019.1{\sim}2040.3cm^{-1}$, $1862.9{\sim}1868.7cm^{-1}$, $1625.7cm^{-1}$ on adsorption and two bands were observed at $2009.5{\sim}2040.3cm^{-1}$, $1828.4{\sim}1868.7cm^{-1}$ on vacumn desorption. These absorption bands correspond with those of the previous reports approximately. For Ru/Ni(9/1, 8/2, 7/3, 6/4, 5/5; mole content ratio)-$SiO_{2}$ samples, three bands were observed at $2001.8{\sim}2057.7cm^{-1}$, $1812.8{\sim}1926.5cm^{-1}$, $1623.8{\sim}1625.7cm^{-1}$ on adsorption and three bands were observed at $2140.6cm^{-1}$, $2073.1cm^{-1}$, $1969.0{\sim}2057.7cm^{-1}$ on vacumn desorption. The spectrum pattern observed for Ru/Ni-$SiO_{2}$ sample at 9/1 Ru/Ni mole content ratio on CO adsorption and on vacumn desorption is almost like the spectrum pattern observed for Ru-$SiO_{2}$ sample. But the spectrum patterns observed for Ru/Ni-$SiO_{2}$ samples under 8/2 Ru/Ni mole content ratio on CO adsorption and vacumn desorption are almost like the pattern observed for $Ni-SiO_{2}$ sample. It may be suggested surfaces of alloy clusters on the Ru/Ni-$SiO_{2}$ samples contain more Ni components than the mole content ratio of the sample considering the above phenomena. With Ru/Ni-$SiO_{2}$ samples the absorption band shifts may be ascribed to variations of surface concentration, strain variation due to atomic size difference, variation of bonding energy and electronic densities, and changes of surface geometries according to surface concentration variation. Studies for CO adsorption on Ru/Ni alloy cluster surface by LEED and Auger spectroscopy, interation between Ru/Ni alloy cluster and $SiO_{2}$, and MO calculation for the system would be needed to look into the phenomena.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.603-618
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• 2023

This study focused on evaluating the suitability of the WRK (waste repository Korea) bentonite as a buffer material in the SNF (spent nuclear fuel) repository. The U (uranium) adsorption/desorption characteristics and the adsorption mechanisms of the WRK bentonite were presented through various analyses, adsorption/desorption experiments, and kinetic adsorption modeling at various pH conditions. Mineralogical and structural analyses supported that the major mineral of the WRK bentonite is the Ca-montmorillonite having the great possibility for the U adsorption. From results of the U adsorption/desorption experiments (intial U concentration: 1 mg/L) for the WRK bentonite, despite the low ratio of the WRK bentonite/U (2 g/L), high U adsorption efficiency (>74%) and low U desorption rate (<14%) were acquired at pH 5, 6, 10, and 11 in solution, supporting that the WRK bentonite can be used as the buffer material preventing the U migration in the SNF repository. Relatively low U adsorption efficiency (<45%) for the WRK bentonite was acquired at pH 3 and 7 because the U exists as various species in solution depending on pH and thus its U adsorption mechanisms are different due to the U speciation. Based on experimental results and previous studies, the main U adsorption mechanisms of the WRK bentonite were understood in viewpoint of the chemical adsorption. At the acid conditions (＜pH 3), the U is apt to adsorb as forms of UO₂²⁺, mainly due to the ionic bond with Si-O or Al-O(OH) present on the WRK bentonite rather than the ion exchange with Ca²⁺ among layers of the WRK bentonite, showing the relatively low U adsorption efficiency. At the alkaline conditions (>pH 7), the U could be adsorbed in the form of anionic U-hydroxy complexes (UO₂(OH)₃^-, UO₂(OH)₄^2-, (UO₂)₃(OH)₇^-, etc.), mainly by bonding with oxygen (O^-) from Si-O or Al-O(OH) on the WRK bentonite or by co-precipitation in the form of hydroxide, showing the high U adsorption. At pH 7, the relatively low U adsorption efficiency (42%) was acquired in this study and it was due to the existence of the U-carbonates in solution, having relatively high solubility than other U species. The U adsorption efficiency of the WRK bentonite can be increased by maintaining a neutral or highly alkaline condition because of the formation of U-hydroxyl complexes rather than the uranyl ion (UO₂²⁺) in solution,and by restraining the formation of U-carbonate complexes in solution.