• Journal of Technologic Dentistry
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• v.39 no.1
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• pp.1-7
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• 2017

Purpose: The purpose of this in vitro study compared to evaluation of repeatability of scanning abutment tooth stone model and impression applied CAD/CAM ISO standard in dentistry. Methods: To evaluate repeatability of scanning abutment tooth stone model, were repeatedly scanned to obtain 11 data via 3D stereolithography (STL) files. 10 data (STL files) were compared with the first 3D data (STL file), and the error sizes were measured by using 3D superimposing software(n=10). Also, the repeatability of scanning abutment tooth impression was evaluated with the same procedure. Independent t test was performed to evaluate the repeatability of scanning abutment tooth stone model versus impression through root mean square(RMS) and standard deviation(SD)(${\alpha}=0.05$). Results: $RMS{\pm}SD$ with regard to repeatability were $14.7{\pm}2.5{\mu}m$, $17.1{\pm}4.0{\mu}m$, respectively, with scanning abutment tooth stone model and impression(p=0.129). Conclusion: This study results showed a little different repeatability of scanning abutment tooth stone model and impression applied CAD/CAM ISO standard in dentistry, will suggest futures good studies and clinical advantages.

• Journal of the Korean Ceramic Society
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• v.40 no.9
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• pp.891-896
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• 2003

Novel fabrication technique was developed for high strength Reaction-Bonded SiC (RBSC) hot gas filter for use in IGCC (Integrated Gasification Combined Cycle) system. The room and high temperature fracture strengths for Si-melt infiltrated reaction-bonded SiC were 50-123, and 60-66 MPa, respectively. The average pore size was 60-70 $\mu\textrm{m}$ and the porosity was about 34 vol％. RBSC infiltrated with molten silicon showed improved fracture strength at high temperature, as compared to that of clay-bonded SiC, due to SiC/Si phase present within SiC phase. The thickness for SiC/Si phase was increased with increasing powder particle size of SiC from 10 to 34 $\mu\textrm{m}$. Pressure drop with dust particles showed similar response as compared to that for Schumacher type 20 filter. The filter fabricated in the present study showed good performance in that the filtered powder size was reduced drastically to below 1 $\mu\textrm{m}$ within 4 min.

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.449-454
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• 1998

It is well known that new tissue or blood vessel is grown into a porous calcium phosphate ceramics used as a bone graft substitute due to their excellent biocompatibility. In this study, the most chemically stable porous $\beta$-crystalline form in various forms of calcium metaphosphate, Ca(PO$_3$)$_2$is prepared by the controlled thermolysis of monocalcium phosphate, Ca(H$_2$PO$_4$)$_2$.The diameter of cylindrical pores formed during cooling was controlled by a holding time at the melting point of a monocalcium phosphate and by the change of a crystallization temperature, to obtain the most appropriate size (about 200$\mu$m) of pores for the application of bone substitutes and matricuts. It was observed that the increasing holding time at the melting point of monocalcium phosphate results in the decreases of cylindrical pore sizes.

• Membrane Journal
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• v.13 no.2
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• pp.88-100
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• 2003

A change of filtrate flux in Taylor vortex flow filtration was investigated experimentally by rotating speed of inner cellulose ester membrane cylinder (average pore size: 1.2 ${\mu}m$), slurry concentration, and particle size. The filtrate flux was a direct proportion relation with TMP, but an inverse relation with resistances. A change of cake resistance with time was examined by rotating speed, slurry concentration, and particle size. Initial resistance increased dramatically as raising slurry concentration, and the pseudo-steady state was maintained at high resistance value. However, times to reach the pseudo-steady state did not depend on slurry concentration. The resistance was larger as smaller particle size, because possibility of pore blocking inside membrane could be higher and shear effect should be lower as smaller particle size. A model equation suggested in this study was composed of particle deposition and removal terms, and could confirm well experimental data using average values of experimental coefficients.

• Applied Chemistry for Engineering
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• v.27 no.2
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• pp.190-194
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• 2016

Tricyclopentadiene (TCPD) is one of the important precursors for making tetrahydrotricyclopentadiene, which is well known as a next-generation fuel with high energy density. In this study, TCPD was obtained by polymerization reaction of dicyclopentadiene (DCPD) using an ionic liquid (IL) supported mesoporous silica catalysts. ILs were supported to two kinds of mesoporous silica catalysts with different pore sizes such as MCM-41 and SBA-15. Four different ILs were supported to mesoporous silicas using anionic precursors such as CuCl or $FeCl_3$ and cationic precursors such as triethylamine hydrochloride or 1-butyl-3-methylimidazolium chloride. We proved that IL supported mesoporous silicas showed better catalytic performance than those of using non-supported prestine IL in the aspect of TCPD yield and DCPD conversion. Among four kinds of IL supported mesoporous silica catalysts, CuCl-based IL supported MCM-41 system showed the highest TCPD yield.

• Analytical Science and Technology
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• v.19 no.4
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• pp.285-289
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• 2006

In this study, the effect of an acidic treatment on granular activated carbon (GAC) and activated carbon fibers (ACF) was investigated for a $Pb^{2+}$ and $Ni^{2+}$ ion adsorption. 1.0 M nitric acid solution was used as the acid solution for the surface treatment. Surface properties of the GAC and ACF were characterized by the pH, elemental analysis and pHpzc (pH of the point of zero charge). Their specific surface area and the pore structure were also evaluated by the nitrogen adsorption data at 77K. As a result, the acidic treatment led to an increase of the oxygen-containing functional groups. Furthermore, the adsorption capacity of the acid-treated GAC and ACF was improved in the order of acidic-ACF > untreated-ACF > acidic-GAC > untreated-GAC, though the decrease in specific surface area induced by a pore blocking of the functional groups was observed.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.391-402
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• 2012

Purpose: This study was survey on future job vision and its pride (self-esteem) of dental technicians. It also investigates the future vision on their major of job (denture) and its awareness to improve the work environment and enhance their satisfaction towards job and duties. Methods: In order to research job and its duty satisfaction of dental technicians who mainly work at denture part, certified questionnaire was modified and upgraded for its use. Collected documents were used by 'Window SAS 8.0 Program' for analysis. The significance of the test related to the items and its standards has been decided for p<0.05. To find out the differences between choices when choosing career and the duty satisfaction, t-test, one-way ANOVA and two-way ANOVA have been used. Results: Following research findings show: 1. There was high self-esteem towards the job as dental technicians but low in future job vision. 2. It has been found that if satisfaction on their job (dental technician) is high then also their satisfaction on its duty (denture part) is high. 3. The factors that affects mostly on duty satisfaction of denture part are 'the contribution on improving oral cavity of people'(${\beta}$=0.33118), 'The possibility of growth of person's job choices'(${\beta}$=0.30035) and 'person's satisfaction on choosing job'(${\beta}$=0.16069). 4. If there is an increase level on the contribution of improving people's oral cavity, the possibility of growth of person's job choices and the person's satisfaction on choosing job, then there is also high growth in denture part's duty satisfaction. 5. It has been found that if there are more employment histories of denture part, the duty satisfaction of denture part were also high. On the other hand, the more employment history of dental technicians get, the duty satisfaction of their denture part was low. Conclusion: Following research results show that there is high self-esteem towards the job as dental technicians but the vision towards future was low. This shows that there is no bright future on dental technology. Therefore, it is important that not only to improve the work environment and pay rise on dental technologists but also to satisfy them. Various program developments and continuous research are needed to increase satisfaction.

• Journal of Conservation Science
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• v.33 no.5
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• pp.363-370
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• 2017

The aim of this study was to obtain information about two early-20th Century clothes, for which the "National Memorial Museum of Forced Mobilization under Japanese Occupation" has sought to receive preservation treatment. Optical microscopes and a scanning electron microscope were used to investigate the weaving of the clothes, and Fourier transform infrared spectroscopy(FT-IR) was used to investigate the fibers. Cloth A is believed to be a Japanese half sleeved inner wear(Hanjuban) used by women. Cloth B is believed to be working clothing that was checked by an Osaka plant. This was verified by a book written by the Japanese army. Both of the clothes were made mostly from cotton, although the inner wear also used viscose rayon on the neck collar. The button on the working wear was made of urea formaldehyde resin, an early precursor to plastic.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.2
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• pp.157-162
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• 1987

The study was carried out to investigate the effects of light intensity, temperature and seasonal trends on the photosynthesis as well as the physiological characteristics of Panax species and cultivars. Four-year-old plant of Violet-stem variant, Yellow-berry variant, Mimaki and Russian ginseng of Panax ginseng C. A. Meyer and American ginseng of Panax quiquefolium L. were used for study. These Panax species and cultivars were cultivated under the straw shading. The light saturation point of leaves in Violet-stem variant, Yellow-berry variant, Mimaki and American ginseng were 15,000 lux, but that of Russian ginseng was 10,000 lux. The optimum air temperature on the phtosynthesis of Violet-stem variant, Yellow-berry variant, Mimaki and American ginseng were 20$^{\circ}C$ but that of Russian ginseng was 15$^{\circ}C$ under 15,000 lux. The photosynthetic rates were increased in order of Russian ginseng, Mimaki, Yellow-berry variant, Violet-stem variant and American ginseng. The respiration rates of ginseng leaves were increased according to the increasing of temperature, but it was not different among Panax species and cultivars. Stomata frequency of American ginseng was highest, that of Russian ginseng lowest, while the length of stomata was reverse. The total chlorophyll content of American ginseng and specific leaf weight of Mimaki were higher than other ginseng cultivars. The root weight of American ginseng was heavier than others, but that of Russian ginseng was lighter. The num ber of leaflets per plant of 2-year-old plant and the root weight of 6-year-old plant were increased in order of Russian ginseng, American ginseng, Mimaki, Yellow-berry variant and Violet-stem variant.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.304-309
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• 1999

Aluminum-pillared clay was prepared by the intercalation of Al-hydroxy oligomer into domestic bentonite. The solid products are characterized by XRD, nitrogen adsorption/desorption, EDX, and SEM. The solid products show relatively high specific surface areas in the range of $104{\sim}228m^2/g$, and their specific surface area, micropore surface area, and micropore volume increase with increasing the mole ratio of OH/Al. From the results of pore size distribution calculated by BJH equation, it was found that aluminum-pillared clay also contains much mesopore near $40{\AA}$. These results indicate that Al-hydroxy oligomer was intercalated into bentonite, and aluminum oxide was pillared among the layers of bentonite, and micropore and mesopore was finally developed into layers. As OH/Al mole ratio increases, the thermal stability of aluminum-pillared clay increases. This result can be explained by the fact that the density of layers is increased due to the formation of aluminum pillars.