• Journal of dental hygiene science
• /
• v.13 no.2
• /
• pp.165-173
• /
• 2013

The purpose of this study was to evaluate the surface change after 15% carbamide peroxide home bleaching to various restorative materials (composite resin [CR], resin modified glass ionomer [RMGI] and glass ionomer [GI]) and to observe the effect of surface condition of the materials on re-staining. Three esthetic restorative materials (Filtek Z250, 3M, USA; Fuji II LC, GC, Japan; Fuji II, GC, Japan) were used in this study. Twenty specimens per material group were made and divided into two groups (bleached and control). The specimens were immersed in coffee after applying bleaching agent. The color change and surface roughness were measured before and after bleaching and after immersion in coffee. The data were analyzed with SPSS 18.0. The results were as follows: 1. The color of all experiment groups was significantly changed after bleaching (p<0.05). RMGI was the greatest value of ${\Delta}E^*$ and ${\Delta}L^*$. GI and CR groups were in ordering (p<0.05). The ${\Delta}a^*$ value was decreased GI, RMGI and CR. RMGI was only significantly decreased in ${\Delta}b^*$ value (p<0.05). 2. The surface roughness before and after bleaching was significantly different on CR, RMGI and GI (p<0.05). 3. After staining with coffee, the value of ${\Delta}E^*$ was increased in GI, RMGI and CR, furthermore GI and RMGI showed significant difference in the bleaching groups (p<0.05). The ${\Delta}L^*$ value of GI and RMGI was significantly decreased. 4. The change of surface roughness after staining was not significantly different in all groups (p>0.05). The maintenance of color stability in esthetic restorations is one of the most important properties. Tooth whitening is for the aesthetic. Therefore, dental professionals should notice to patients about re-staining after tooth whitening. They should give an instruction that how to prevent and which kinds of agents could be stained.

• Journal of Korean Ophthalmic Optics Society
• /
• v.7 no.2
• /
• pp.19-25
• /
• 2002

Ternary $xSrO-yB_2O_3-0.1Al_2O_3$ and $xSrO-yB_2O_3-0.1SiO_2$ glasses were prepared as a function of R(${\equiv}x/y$). The fraction of four-coordinated brans ($N_4$), symmetric three-coordinated barons ($N_{3S}$), and asymmetric three-coordinated barons ($N_{3A}$) were determined quantitatively to study the structures of these glasses by $^{11}B$ NMR. The values of $Q_{cc}$ and ${\eta}$ for $BO_3$ unit in the glasses were 2.74MHz and 0.22, those for $BO_3{^-}$ unit were 2.54MHz and 0.55, and those for $BO_4$ unit 0.60~0.75MHz and 0.00, respectively. The structure of SrBAl glass at $R_{1st}$ consisted of tetraborate ($[B_8O_{13}]^{-2}$) units and 1st-modified diborate ($[B_2Al_2O_7]^{-2}$) units, and those for the glass at $R_{max}$consisted of diborate ($[B_4O_7]^{-2}$) units, metaborate ($[BO_2^{-1}]$), 1st-modified diborate units, and 2nd-modified diborate ($[B_2Al_2O_8]^{-4}$) units. Due to the oxygens introduced from the strontium oxide. $AlO_4$ units were preferably formed rather than $BO_4$ units. And, the structure of SrBSi glasses in the region $R{\leq}0.5$ could be viewed as binary $SrO-B_2O_3$ glasses structure diluted by silicate oxide: therefore, the Si atoms of the glasses did not contributed to the change the configuration around the boron atoms. The silicate oxide was formed the $SiO_4{^-}$ units rather than the $BO_3{^-}$ units by the oxygens introduced from the storntium oxide in the region of $R{\geq}R_{max}$, and structure of those glass at $R_{max}$ consisted of diborate units, metaborate units loose $BO_4([BO_2]^{-1})$, and $SiO_4{^-}([SiO_{2.5}]^{-1})$ units.

• Journal of the Korean Chemical Society
• /
• v.48 no.1
• /
• pp.77-84
• /
• 2004

The purpose of this study was to analyze the controversial points in the concepts of materials in the science textbook of middle school and to provide alternatives of teaching method. For this study, units in connected textbooks were analyzed and the teaching method using ball-and-stick models was developed. The subjects were 130 second graders from a middle school in Seoul, Korea. It aimed to compare the effectiveness of using ball-and-stick models for lesson with the one of traditional lessons, in learning concepts concerning materials by cognitive levels and to investigate the difference of scientific concept formation about concepts concerning materials by their cognitive levels between experimental group and control group by using concept formation questionnaires. Before the instructions, a short-version GALT was administered. After instructions, the posttest of concepts and attitude test connected with science subject were administered, and 10 months later, the posttest of concepts was administered to analyze the long-term memory effects. According to the results, the experimental group using the ball-and-stick models had significantly higher scores at conceptual understanding and long-term memory effects than the control group and improved the attitude relevant to science subject, and also had affirmative effects in attitude for science and science work. When analyzing the results according to the cognitive level, the long-term memory effects was high in the concrete operational stage students. From the results of this study, middle school students that are more concrete operational stage and transitional stage than formal operational stage elevates interesting in studying by using ball-and-stick models and making material form concretely. It would be effective in helping the students develope the correct concepts by connecting real world as materials and the particle world as atom.

• Journal of the Korean Chemical Society
• /
• v.55 no.3
• /
• pp.418-429
• /
• 2011

Novel chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), ruthenium(III), and zirconyl(II) complexes of $N^1,N^2$-bis(3-((3-hydroxynaphthalen-2-yl)methylene-amino)propyl)phthalamide ($H_4L$, 1) have been synthesized and characterized by elemental, physical, and spectral analyses. The spectral data showed that the ligand behaves as either neutral tridentate ligand as in complexes 2-5 with the general formula $[H_4LMX_2(H_2O)]{\cdot}nH_2O$ (M=Cu(II), Ni(II), Co(II), X = Cl or $NO_3$), neutral hexadentate ligand as in complexes 10-12 with the general formula $[H_4LM_2Cl_6]{\cdot}nH_2O$ (M=Fe(III), Cr(III) or Ru(III)), or dibasic hexadentate ligand as in complexes 6-9 with the general formula $[H_2LM_2Cl_2(H_2O)_4]{\cdot}nH_2O$ (M = Cu(II), Ni(II), Co(II) or Mn(II), and 13 with general formula $[H_4L(ZrO)_2Cl_2]{\cdot}8H_2O$. Molar conductance in DMF solution indicated the non-ionic nature of the complexes. The ESR spectra of solid copper(II) complexes 2, 5, and 6 showed $g_{\parallel}$ >g> $g_e$, indicating distorted octahedral structure and the presence of the unpaired electron in the $N^1,N^2$ orbital with significant covalent bond character. For the dimeric copper(II) complex $[H_2LCu_2Cl_2(H_2O)_4]{\cdot}3H_2O$ (6), the distance between the two copper centers was calculated using field zero splitting parameter for the parallel component that was estimated from the ESR spectrum. The antibacterial and antifungal activities of the compounds showed that, some of metal complexes exhibited a greater inhibitory effect than standard drug as tetracycline (bacteria) and Amphotricene B (fungi).

• Journal of Life Science
• /
• v.16 no.2 s.75
• /
• pp.206-212
• /
• 2006

In order to synthesize novel anticonvulsants, we researched that the reactions of diamines with 2,5-dimethoxytetrahydrofuran and 1,3-acetonedicarboxylic acid. The reaction of ethylenediamine with 2,5-dimethoxytetrahydrofuran and 1,3-acetonedicarboxylic acid afforded 8-(2-pyrrol-1-yl-ethyl)-8-aza-bicyclo[3,2,1]octan-3-one (yield; 5.0%) and 1,2-di-(8-aza-bicyclo[3,2,1]octan3-onyl)ethane (yield; 17.0%). In case of 1,3-diaminopropane, 8-(3-pyrrol-1-yl-propyl)-8-aza-bicyclo[3,2,1]octan-3-one(yield; 6.0%) and 1,3-di-(8-aza-bicyclo[3,2,1]octan-3-onyl)propane (yield; 21.0%) were obtained. In case of 1,8-diaminooctane, 8-(8-pyrrol-1-yl-octyl)-8-aza-bicyclo-[3,2,1]octan-3-one (yield; 2.6 %) and 1,8-di-(8-aza-bicyclo[3,2,1]octan-3-onyl)octane (yield; 24.9%) were obtained. In diaminobenzene reactions, synthetic yields of 8-aza-bicyclo-[3,2,1]octan-3-one derivatives were higher than those of pyrrole derivatives because re actions were done under room temperature. The longer the carbon chain of diaminoalkane is, the more reactive N atom is due to more electron donating effect, and the less steric hindrance around the carbon gave the higher chemical yields. The reaction of p-phenylenediamine as a diaminobenzene with 2,5-dimethoxyte-trahydrofuran and 1,3-acetonedicarboxylic acid produced p-dipyrrolylbenzene (yield; 4.0%), 8-(4-pyrrol-1-yl-phenyl)-8-aza-bicyclo[3,2,1]octan-3-one (yield; 12.0%), and 1,4-di-(8-aza-bicyclo[3,2,1]octan-3-onyl)benzene (yield; 59.0%). In case of m-phenylenediamine, 8-(3-pyrrol-1-yl-phenyl)-8-aza-bicyclo[3,2,1]octan-3-one(yield; 2.0%) and 1,3-di-(8-aza-bicyclo[3,2,1]octan-3-onyl)benzene (yield ; 28.0%) were obtained. But, synthesis of 1,2-di-(8-aza-bicyclo[3,2,l]octan-3-onyl)benzene by treatment of o-phenylenediamine was not successful, presumably due to the steric hindrance of 8-aza-bicyclo-[3,2,1]octan-3-one rings.

• Journal of Radiation Protection and Research
• /
• v.39 no.1
• /
• pp.21-29
• /
• 2014

A new cold neutron triple-axis spectrometer (Cold-TAS) was recently constructed at the 30 MWth research reactor, HANARO. The spectrometer, which is composed of neutron optical components and radiation shield, required a redesign of the segmented monochromator shield due to the lack of adequate support of its weight. To shed some weight, lowering the height of the segmented shield was suggested while adding more radiation shield to the top cover of the monochromator chamber. To investigate the radiological effect of such change, we performed MCNPX simulations of a few different configurations of the Cold-TAS monochromator shield and obtained neutron and photon intensities at 5 reference points just outside the shield. Reducing the 35% of the height of the segmented shield and locating lead 10 cm from the bottom of the top cover made of polyethylene was shown to perform just as well as the original configuration as radiation shield excepting gamma flux at two points. Using gamma map by MCNPX, it was checked that is distribution of gamma. Increased flux had direction to the top and it had longer distance from top of segmented shield. However, because of reducing the 35% of the height, height of dissipated gamma was lower than original geometry. Reducing the 35% of the height of the segmented shield and locating lead 10cm from the bottom of the top cover was selected. After changing geometry, radiation dose was measured by TLD for confirming tester's safety at any condition. Neutron(0.21 ${\mu}Svhr^{-1}$) and gamma(3.69 ${\mu}Svhr^{-1}$) radiation dose were satisfied standard(6.25 ${\mu}Svhr^{-1}$).

• Journal of Preventive Medicine and Public Health
• /
• v.26 no.4 s.44
• /
• pp.628-649
• /
• 1993

This study was conducted to investigate the factors related to the poor school performance of the elementary school children. Two schools in Taegu, one in the affluent area and the other in the poor area, were selected and a total of 175 children whose school performance was within low 10 percentile (poor performers) and 97 children whose school performance were within high 5 percentile (good performers) in each class of 2nd, 4th and 6th grades were tested for the physical health, behavioral problem and family background. Each child had gone through a battery of tests including visual and hearing acuity, anthropometry (body weight, height, head circumference), intelligence (Kodae Stanford-Binet test), test anxiety (TAI-K), neurologic examination by a developmental pediatrician and heavy metal content (Pb, Cd, Zn) in hair by atomic absorption spectrophotometry. A questionnaire was administered to the mothers for prenatal and prenatal courses of the child, family environment, child's developmental history, and child's behavioral and learning problems. Another questionnaire was administered to the teachers of the children for the child's family background, arithmatic & language abilities and behavioral problem. The poor school performance had a significant correlation with male gender, high birth order, broken home, low educational and occupational levels of parents, visual problem, high test anxiety score, attention deficit hyperactivity disorder (ADHD), poor physical growth (weight, height, head circumference) and low I.Q. score. The factors that had a significant correlation with the poor school performance in multiple logistic regression analysis were child's birth order (odds ratio=2.06), male gender(odds ratio=5.91), broken home(odds ratio=9.29), test anxiety score(odds ratio=1.07), ADHD (odds ratio=9.67), I.Q. score (odds ratio=0.85) and height less than Korean standard mean-1S.D.(odds ratio=11.12). The heavy metal contents in hair did not show any significant correlation with poor school performance. However the lead and cadmium contents were high in males than in females. The lead content was negatively correlated with child's grade(P<0.05) and zinc was positively correlated with grade (P<0.05). among the factors that showed a significant correlation with the poor school performance, high birth order, short stature and ADHD may be modified by a good family planning, good feeding practice for infant and child, and early detection and treatment of ADHD. Also, teacher and parents should restrain themselves from inducing excessive test anxiety by forcing the child to study and over-expecting beyond the child's intellectual capability.

• Journal of environmental and Sanitary engineering
• /
• v.3 no.2 s.5
• /
• pp.61-78
• /
• 1988

This study was carried out to clarify the effect of dietary calcium, casein and suet on intestinal absorption of cadmium in mice. It was performed for 30 days, from April 11, to May 10, 1988. Ninety mice were devided into 4 experimental groups and control group with 6 mice each dietary group, and measured survival ratio, body weight and weight ratio of organ to body. The contents of cadmium in liver, kidney, spleen, muscle and skin with hair, and feces were analyzed by atomic absorption spectrophotometer after sacrifice by anesthesia. The ratio of survival after 30 day breeding was $100\%$ in control group, but $66.7\%$ in group IV(basal diet + Cd + Ca) with $100{\mu}g$ one dose and with 50ppm cadmium containing fluid free-intake, and group V (basal diet + Cd + suet) with free-intake of 50ppm containing cadmium fluid. The ratio of body weight gains in cases of single dose $100{\mu}g$ of cadmium was highest as $42.3\%$ in group IV and lowest as $26.0\%$ in group V, in cases of free-intake of 50ppm containing cadmium fluid was highest as $24.0\%$ in group IV and lowest as $11.6\%$ in group II (basal diet + Cd). The body weight, in the case of single dose of $100{\mu}g$ of cadmium showed no increase untill 5th day from acute poisoning. While in case of free-intake of 50ppm containing cadmium, it showed very slight increase through all breeding period. The weight ratio of organ to body were lowest in liver of group II in both occasions. The most of cadmium administered was excreated in feces within 2 days after single dose $100{\mu}g$ cadmium. The contents of cadmium in all tissues were significantly high in each group comparing to control group as liver, kidney, spleen and muscle of group II which showed the highest level in both occasions of $100{\mu}g$ one dose and free-intake of 50ppm containing cadmium fluid, and higher in group II of the occasion with $100{\mu}g$ single dose, and in group V of the occasion of 50ppm containing cadmium fluid free-inatke for skin with hair. And the content of cadmium in tissues is generally higher in the occasion of 50ppm containing cadmium free-intake than $100{\mu}g$ single dose. From the above results I conclude that the addition of casein, calcium and suet in cadmium containing diet is effective to inhibtion of intestinal absorption of cadmium by particularly, calcium.

• Journal of the Korean Vacuum Society
• /
• v.22 no.6
• /
• pp.313-320
• /
• 2013

The $AlAs_xSb_{1-x}$ step-graded buffer (SGB) layer was grown on the Silicon (Si) substrate to overcome lattice mismatch between Si substrate and $Al_{0.3}Ga_{0.7}As$/GaAs multiple quantum wells (MQWs). The value of root-mean-square (RMS) surface roughness for 5 nm-thick GaAs grown on $AlAs_xSb_{1-x}$ step-graded buffer layer was ~1.7 nm. $Al_{0.3}Ga_{0.7}As$/GaAs MQWs with AlAs/GaAs short period superlattice (SPS) were formed on the $AlAs_xSb_{1-x}$/Si substrate. Photoluminescence (PL) peak at 10 K for the $Al_{0.3}Ga_{0.7}As$/GaAs MQW structure showed relatively low intensity at ~813 nm. The RMS surface roughness of the $Al_{0.3}Ga_{0.7}As$/GaAs MQW structure was ~42.9 nm. The crystal defects were observed on the cross-sectional transmission electron microscope (TEM) images of the $Al_{0.3}Ga_{0.7}As$/GaAs MQW structure. The decrease of PL intensity and increase of RMS surface roughness would be due to the formation of the crystal defects.

• The KIPS Transactions:PartD
• /
• v.14D no.1 s.111
• /
• pp.121-130
• /
• 2007

in a software development, the design or architecture prior to implementing the software is essential for the success. This paper presents a case that we successfully designed a software architecture of radiation monitoring system (RMS) for HANARO research reactor currently operating in KAERI by applying the quality attribute-driven design method which is modified from the attribute-driven design (ADD) introduced by Bass[1]. The quality attribute-driven design method consists of following procedures: eliciting functionality and quality requirements of system as architecture drivers, selecting tactics to satisfy the drivers, determining architectures based on the tactics, and implementing and validating the architectures. The availability, maintainability, and interchangeability were elicited as duality requirements, hot-standby dual servers and weak-coupled modulization were selected as tactics, and client-server structure and object-oriented data processing structure were determined at architectures for the RMS. The architecture was implemented using Adroit which is a commercial off-the-shelf software tool and was validated based on performing the function-oriented testing. We found that the design method in this paper is an efficient method for a project which has constraints such as low budget and short period of development time. The architecture will be reused for the development of other RMS in KAERI. Further works are necessary to quantitatively evaluate the architecture.