• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.135-142
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• 2010

Purpose: This study was aimed to compare the margin and internal fitness of single anterior all-ceramic crown zirconia core made by three deferent CAD/CAM systems. Material and methods: Five single zirconia cores were manufactured by three deferent CAD/CAM systems($Cerasys^{(R)}$system, KaVo $Everest^{(R)}$system, $LAVA^{TM}$system). The manufactured zirconia cores were duplicated through the use of replica technique, and a replicated sample was sectioned in the center of bucolingual and mesiodistal direction to measure the marginal and internal gap. Measurement was carried out by using measuring microscope ($AXIO^{(R)}$) and $I-Solution^{(R)}$ and analysed through the use of ANOVA. Results: As for the mean marginal fitness of the zirconia core, it was $84.74{\pm}27.57{\mu}m$, in $Cerasys^{(R)}$, $80.23{\pm}21.07{\mu}m$ in KaVo $Everest^{(R)}$ and $96.37 {\pm}11.45{\mu}m$ in $LAVA^{TM}$, and as for the mean internal gap, it was $94.11{\pm}30.07{\mu}m$ in $Cerasys^{(R)}$, $92.31{\pm}25.18{\mu}m$ in KaVo $Everest^{(R)}$, and $94.99{\pm}18.74 {\mu}m$ in $LAVA^{TM}$. There was no significant statistically deference among the total average gap of three systems. The internal gap in KaVo $Everest^{(R)}$ seemed to be smaller than $LAVA^{TM}$ (P < .05). The internal gap in the incisal area was larger in all of the three systems. Conclusion: There was no difference in marginal fitness in $Cerasys^{(R)}$, KaVo $Everest^{(R)}$ and $LAVA^{TM}$. As for the internal fitness, it was smaller in KaVo $Everest^{(R)}$ system than $LAVA^{TM}$ system. In all of the three systems, there was a larger gap in incisal area. The marginal and internal gap was within the clinically allowed range in all of the three systems.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.193-202
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• 2016

Purpose: This study was performed in order to assess the effect of the surface treatment methods and the use of bonding agent on the shear bond strength (SBS) between the aged CAD-CAM (computer aided design-computer aided manufacturing) hybrid materials and added composite resin. Materials and methods: LAVA Ultimate (LU) and VITA ENAMIC (VE) specimens were age treated by submerging in a $37^{\circ}C$ water bath filled with artificial saliva (Xerova solution) for 30 days. The surface was ground with #220 SiC paper then the specimens were divided into 9 groups according to the combination of the surface treatment (no treatment, grinding, air abrasion with aluminum oxide, HF acid) and bonding agents (no bonding, Adper Single Bond 2, Single Bond Universal). Each group had 10 specimens. Specimens were repaired (added) using composite resin (Filtek Z250), then all the specimens were stored for 7 days in room temperature distilled water. SBS was measured and the fractured surfaces were observed with a scanning electron microscope (SEM). One-way ANOVA and Scheffe test were used for statistical analysis (${\alpha}=.05$). Results: Mostly groups with bonding agent treatment showed higher SBS than groups without bonding agent. Among the groups without bonding agent the groups with aluminum oxide treatment showed higher SBS. However there was no significant difference between groups except two subgroups within LU group, which revealed a significant increase of SBS when Single Bond Universal was used on the ground LU specimen. Conclusion: The use of bonding agent when repairing an aged LAVA Ultimate restoration is recommended.

• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.268-273
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• 1998

Changes of chemical component and losses of chemical fertilizer by infiltration water from 0.5ha of paddy field in Chinan area of Chonbuk province during the rice cultivation were investigated. The infiltration water samples were collected in a ceramic porous cup which was a buried at the 30, 50, 70, 90㎝ of soil depth. pH of infiltration water ranged $6.64{\sim}7.90$ and EC showed $324{\sim}647{\mu}$S/cm. The content of total-N, $NH_4-N$ and $NO_3-N$ were $0.58{\sim}14.59$, $0.05{\sim}4.25$, and $0.15{\sim}7.71mg/L$ respectively. The content of total-P and ortho-P were $0.009{\sim}0.077mg/L$ and $0{\sim}0.029mg/L$ The content of $Ca^{++}$, $Mg^{++}$, $Na^{+}$ and $K^{+}$ showed $0.88{\sim}4.78$, $0.22{\sim}1.04$, $0.17{\sim}0.98$, and $0.84{\sim}3.19㎎/L$. These all at the first transplanting are higher than that of other periods. The content of $SO_4^{2-}$ showed $3.92{\sim}18.72mg/L$ and decreased with a soil depth. However $Cl^-$ of infiltration water ranged $9.03{\sim}19.97mg/L$ and no difference with a soil depth. When infiltrated $2,416.5m^{3}$ of an infiltration water from 0.5ha of paddy field during the rice cultivation, losses of chemical components were 20.34㎏/㏊ of total-N, 3.54㎏/㏊ of $NH_4-N$, 10.44㎏/㏊ of $NO_3-N$, 0.16㎏/㏊ of total-P and 0.028㎏/㏊ of ortho-P. Also $Ca^{++}$, $Mg^{++}$, $Na^+$, $K^+$, $SO_4^{2-}$ and $Cl^-$ were lost 10.24, 2.84, 2.84, 7.22, 50.04 and 62.20㎏/㏊ respectively. There were lost by infiltration water 9.35% of nitrogen, 0.59% of phosphorous and 22.79% of potassium in applied chemical fertilizer.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.145-156
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• 1997

ZrO2 phase transformations depending on the type and amount of dopants and the sintering temperatures were studied for the 2 components (CaO-, Y2O3-, MgO-ZrO2) and the 3 components(MgO-ZrO2-Al2O3)ZrO2 powder by X-ray diffraction and Raman spectroscopy. In the CaO- and Y2O3-ZrO2 systems, as the CaO and Y2O3 contents increased to 6~15mol% and 3~15mol% respectively, we were not able to identify between tetragonal and cubic in the X-ray diffraction patterns. On the other hand, all Raman modes shifted to lower wavenumbers, decreasing in intensity and the number of bands, markedly. These phenomena were caused by tetragonallongrightarrowcubic phase transformation and interpreted by the breakdown of the wave vector selection rule(k=0) and the structural disorder associated with the formation of oxygen sublattice which was caused by the substitution between Zr4+ ion and Ca2+ or Y3+ ion in ZrO2 matrix. The monoclinic to cubic phase transformation occurred in 10mol% MgO-ZrO2 system. As the Al2O3 content increased from 0 to 20mol% in the MgO-ZrO2-Al2O3 systems, cubic phase transformed to monoclinic phase, this is because the MgO didn't play a role in a stabilizer because of the formation of the spinel(MgAl2O4) by the reaction between MgO and Al2O3, Also, the ZrO2 phase transformation was explained by the change of it's lattice parameters depending on the type and amount of dopants. Namely, as the amount of dopant increased to 10~13mol%, the axial ra-tio c/a came close to unity with increasing the lattice parameter a and decreasing the lattice parameter c. At that time, the tetragonallongrightarrowcubic phase transformation occurred.

• Journal of Bio-Environment Control
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• v.19 no.3
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• pp.159-164
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• 2010

This study was carried out to compare the storability of Salsola komarovi Iljin and Suaeda maritima L. Dum which stored at different storage temperatures in MA storage. These plants that had grown in greenhouse packed with $50\;{\mu}m$ ceramic film and then stored in $2^{\circ}C$, $10^{\circ}C$, and $25^{\circ}C$ temperature. The fresh weight loss both plants was less than 1% in all temperature treatments. The highest fresh weight loss showed at $25^{\circ}C$ among storage temperature treatments in Salsola komarovi Iljin between plants. The highest carbon dioxide contents in package showed at $25^{\circ}C$ among storage temperature treatments in Salsola komarovi Iljin between plants, and at $2^{\circ}C$ and $10^{\circ}C$ temperature treatments remained less than 1%. Oxygen contents in package both plants showed the highest level at $2^{\circ}C$ temperature treatment, but Salsola komarovi Iljin showed less oxygen contents than Suaeda maritima L. Dum. Although there was no significant difference ethylene contents in package between $2^{\circ}C$ and $10^{\circ}C$ temperature treatments, the higher showed in $10^{\circ}C$ than $2^{\circ}C$ temperature treatments. The ethylene contents in package both plants were roughly $20\;{\mu}L{\cdot}L^{-1}$ and the higher was in Suaeda maritima L. Dum than Salsola komarovi Iljin at $2^{\circ}C$. As increasing the storage temperature, the contents of carbon dioxide and ethylene in package also increased in both plants. The carbon dioxide and ethylene contents of Salsola komarovi Iljin showed a significant difference between $2^{\circ}C$ and $10^{\circ}C$ temperature treatments, but Suaeda maritima L. Dum did not show. The shelf life of Salsola komarovi Iljin based on visual quality was 14 days at $2^{\circ}C$ temperature treatment and 7.5 days at $10^{\circ}C$ temperature treatment. However, the shelf life of Suaeda maritima L. Dum did not show a significant difference between $2^{\circ}C$ temperature treatment that was 11 days, and $10^{\circ}C$ temperature treatment that was 9.5 days. Considering visual quality and gas contents in package, Suaeda maritima L. Dum might appear chilling injury at $2^{\circ}C$ temperature treatment.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.103-110
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• 2003

Stable production of fermented kanjang containing 1.8% (v/v) ethanol was obtained within four days using traditional kanjang containing 4% added glucose in packed-bed bioreactor systems filled with immobilized Zygosaccharomyces rouxii and Candida versatilis on porous alumina ceramic bead carrier at $28{\pm}0.5^{\circ}C$ and aeration rate of 0.05 vvm. Specific rates of alcohol production for Z. rouxii and C. versatilis were 0.0033 and 0.0031/day, respectively, and those of glucose consumption were both -0.0087/day in the batch type of alcoholic fermentation. In semi-continuous alcoholic fermentation at a dilution rate of 0.25/day, specific rates of alcohol production for Z. rouxii and C. versatilis were 0.0045 and 0.0029/day, and those of glucose consumption were -0.01 and -0.008/day, respectively, using identical bioreactor system. Similar specific rates of alcohol production were observed both in the batch or semi-continuous process and in the continuous one at the dilution rate of 0.25/day. Sensory characteristics of all alcoholic-fermented kanjang by Z. rouxii, C. versatilis, and a mixture of both yeasts (2:1, w/w) were shown to be significantly superior to those of home-made kanjang as revealed through organoleptic evaluation tests (p<0.05).

• The korean journal of orthodontics
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• v.40 no.5
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• pp.294-303
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• 2010

Objective: This study was designed to measure the surface roughness at the slot floor of various ceramic brackets. Methods: One kind of stainless steel bracket ($Succes^{(R)}$), two kinds of monocrystalline brackets (Inspire $Ice^{(R)}$, $Perfect^{(R)}$) and two kinds of polycrystalline brackets (Crystalline $V^{(R)}$, $Invu^{(R)}$) were examined. Atomic force microscopy (AFM) was used to measure the surface roughness of each bracket. Data acquisition and processing were performed using $SPIP^{TM}$. Results: The differences in values of Sa, Sq, and Sz in $Invu^{(R)}$ and Inspire $Ice^{(R)}$ were not statistically different from the control group $Succes^{(R)}$. The values of Sa, Sq, and Sz of $Perfect^{(R)}$ and Crystalline $V^{(R)}$ were greater than those of $Succes^{(R)}$. Differences of all the Sa, Sq, and Sz values between $Perfect^{(R)}$ and Crystalline $V^{(R)}$ were not statistically significant. Conclusions: It is concluded that the slot surfaces of $Succes^{(R)}$, Inspire $Ice^{(R)}$, and $Invu^{(R)}$ were smooth compared to those of Crystalline $V^{(R)}$ and $Perfect^{(R)}$.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.24-30
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• 2003

A formation and conversion of AFm phases decisively play role in the hydration, hardening and corrosion processes of various cement. In this study, the conversion of Alumino-Ferrite Monohydrates(AFm) phases under the addition of $CaCO_3,;CaCl_2;and;CaSO_4{cdot}2H_2O$was investigated by the XRD quantitative analysis. The thypical AFm phases are $M_S(monosulfoaluminate),;M_C(monocarboaluminate);and;M_{Cl}(monochloroaluminate and also Called Friedel's salts)$in this cementitious system, The conversion reaction were not occurred in $M_C-CaCO_3,;M_{Cl}-CaCO_3$ and $M_{Cl}-CaCl_2$system. However, in $M_S-CaCO_3$ system, ettringite and $monocarboaluminate(M_C)$ were formed. In $M_S-CaCl_2;system;M_S$ was transformed to Friedel's $salts(M_{Cl})$ and ettringite was formed. In the case of $CaSO_4{cdot}2H_2O$ addition, all AFm $phases(M_S,;M_C;and;M_{Cl})$ were transformed to ettringite. The order of stabilization of AFm phases under $CaCO_3,;CaCl_2;and;CaSO_4{cdot}2H_2O$ was as follows : $M_S< M_C

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.3
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• pp.157-170
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• 2002

The purpose of this study is to analyze the shear bond strength according to kinds of surface treatment agents and resin cements after acid etching of IPS Empress 2. For this purpose, test groups were classified into silane-treated bonding groups, silica-coated group and Targis link applied group. Then, nine bonding groups in total, each three groups per kind, were prepared by using three kinds of resin cements-Panavia F, Variolink II and Rely-X ARC, and thirty test specimens per group were prepared. To examine any changes in the oral environment, the shear bond strength of each test specimen was measured after dipping test for 24 hours and for five weeks, respectively, in distilled water at $37^{\circ}C$ and performing heat cycle 10,000 times in total, each 2,000 times per week, during a five weeks of dipping, under the condition similar to the oral environment. The bond failure modes were also observed by means of a scanning electron microscope. The results are summarized as follows 1. Statically significant differences between the surface conditioning materials were observed. The shear strength of the silane treatment was the highest of all three types of surface treatments(p<0.001). 2. Shear strengths varied significantly for different types of resin luting agents. But bond strength of Targis link surface treatments were not significantly different(p<0.05). 3. No significant difference of bonding strengths was found between storage time conditions(24 hours and 5 weeks). Only group II, IV, VII, IX were significantly different(p<0.05). 4. After thermocycling, the shear bond strengths of all groups were significantly decreased (p<0.05). Group III, V, VI were no significantly different. 5. On the SEM observation of fractured surfaces, all groups were shown complex failure.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.231-239
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• 2000

This study was investigated to estimate optimal conditions and biological oxic denitrification to treat wastewater with low C/N ratio and high strength total inorganic nitrogen (TIN) concentration by using $A_2O$ fixed biofilm system. The lab-scale experimental system packed with media, which were composed of polyvinylidene chloride fiber (oxic basin) and ceramic ball (anaerobic and anoxic basin), was used. This system was operated with various influent alkalinities at the C/N(TOC/TIN) ratio of 0.5. The study results showed that TOC were removed over 96.0% at all operation conditions. The removal efficiencies over 93.5% for $NH_4{^+}-N$ and 81.8% for TIN were obtained at the alkalinity of about 1210mg/L(Run 5). Among the removal of TIN, 64.9% was occurred by biological denitrification at an oxic basin. It was confirmed through mass balance of alkalinity and nitrogen that the amount of alkalinity produced during biological denitrification at oxic basin was 2.49~3.46 mg Alkalinity/mg $NO_2{^-}-N$, ${\Delta}TOC/{\Delta}DEN$ of 0.34 (Run 5) was obtained at an oxic basin, which was less than the theoretical value of 1.22.