• Journal of the Korean Applied Science and Technology
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• v.28 no.2
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• pp.251-257
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• 2011

The processes for the preparation of ZnO powder by using EAF(electric arc furnace)dust was studied by wetting method which are divided to two steps, carried out of the elution processes by various concentrations of sulfuric acid is reacted with EAF dust as the former, and the latter were performed by a number of specified processes, which are leaching process depends on various pH, cementation, ozone and heat treatment processes etc. Experimental results showed that the appropriate pH range is pH7.5~8.0 and the resulting zinc content is range of 37~38%, the residual quantities of the heavy metals are less than 3ppm individually by cementation process except Mn, even though the Mn metal could not be removed by cementation process but was removed up to 0.2ppm by the ozone process from 70ppm initially. Finally, 80.2% of ZnO was obtained by the heat treatment at $500^{\circ}C$.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3235-3241
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• 2022

The Korea Atomic Energy Research Institute (KAERI) is planning the construction of the KIJANG Research Reactor (KJRR) for stable supply of ⁹⁹Mo. The Fission ⁹⁹Mo Production Process (FMPP) of KJRR produces solid waste such as spent uranium cake and alumina cake, and liquid waste in the form of intermediate level liquid waste (ILLW) and low level liquid waste (LLLW). This study thus established the operating range and optimum operating conditions for the cementation of ILLW from FMPP. It also evaluated whether cement waste form samples produced under optimum operational conditions satisfy the waste acceptance criteria (WAC) of a disposal facility in Korea (Korea radioactive waste agency, KORAD). Considering economic feasibility and safety, optimum operational conditions were achieved at a w/c ratio of 0.55, and the corresponding salt content was 5.71 wt%. The cement waste form samples prepared under optimum operational conditions were found to satisfy KORAD's WAC when tested for structural stability and leachability. The results indicate that the proposed cementation conditions for the disposal of ILLW from FMMP can be effectively applied to KJRR's disposal facility.

• Restorative Dentistry and Endodontics
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• v.44 no.4
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• pp.37.1-37.10
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• 2019

Objectives: This study evaluated the bond strength of various fiberglass post cementation techniques using different resin-based composites. Materials and Methods: The roots from a total of 100 bovine incisors were randomly assigned to 5 treatment groups: G1, post + Scotchbond Multi-Purpose (SBMP) + RelyX ARC luting agent; G2, relined post (Filtek Z250) + SBMP + RelyX ARC; G3, individualized post (Filtek Z250) + SBMP; G4, individualized post (Filtek Bulk-Fill) + SBMP; G5, individualized post (Filtek Bulk-Fill Flow) + SBMP. The samples were subjected to the push-out (n = 10) and pull-out (n = 10) bond strength tests. Data from the push-out bond strength test were analyzed using 2-way analysis of variance (ANOVA) with the Bonferroni post hoc test, and data from the pull-out bond strength test were analyzed using 1-way ANOVA. Results: The data for push-out bond strength presented higher values for G2 and G5, mainly in the cervical and middle thirds, and the data from the apical third showed a lower mean push-out bond strength in all groups. No significant difference was noted for pull-out bond strength among all groups. The most frequent failure modes observed were adhesive failure between dentine and resin and mixed failure. Conclusions: Fiberglass post cementation using restorative and flowable bulk-fill composites with the individualization technique may be a promising alternative to existing methods of post cementation.

• The Journal of Advanced Prosthodontics
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• v.7 no.3
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• pp.257-263
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• 2015

PURPOSE. In this study, we aimed to evaluate the amount of marginal gap with two different substructure materials using identical margin preparations. MATERIALS AND METHODS. Twenty stainless steel models with a chamfer were prepared with a CNC device. Marginal gap measurements of the galvano copings on these stainless steel models and Co-Cr copings obtained by a laser-sintering method were made with a stereomicroscope device before and after the cementation process and surface properties were evaluated by scanning electron microscopy (SEM). A dependent t-test was used to compare the mean of the two groups for normally distributed data, and two-way variance analysis was used for more than two data sets. Pearson's correlation analysis was also performed to assess relationships between variables. RESULTS. According to the results obtained, the marginal gap in the galvano copings before cementation was measured as, on average, $24.47{\pm}5.82{\mu}m$ before and $35.11{\pm}6.52{\mu}m$ after cementation; in the laser-sintered Co-Cr structure, it was, on average, $60.45{\pm}8.87{\mu}m$ before and $69.33{\pm}9.03{\mu}m$ after cementation. A highly significant difference (P<.001) was found in marginal gap measurements of galvano copings and a significant difference (P<.05) was found in marginal gap measurements of the laser-sintered Co-Cr copings. According to the SEM examination, surface properties of laser sintered Co-Cr copings showed rougher structure than galvano copings. The galvano copings showed a very smooth surface. CONCLUSION. Marginal gaps values of both groups before and after cementation were within the clinically acceptable level. The smallest marginal gaps occurred with the use of galvano copings.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1431-1437
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• 2008

The small-strain shear modulus ($G_{max}$) of uncemented sand is affected by the the mean principal stress and void ratio, and it has been known that the cementation and aging also affect to $G_{max}$ of sand. For extensive understanding about the effect of cementation on the $G_{max}$ of sand, a series of bender element tests was conducted on the cemented specimens prepared in a large calibration chamber by pluviation of the sand-gypsum mixture. It was observed from the experimental results that the $G_{max}$ of cemented sand is higher above 10 times than value of uncemented one, and it increases exponentially with the gypsum content increases. Whereas, the increase of the vertical stress from 50kPa to 200kPa and the relative density from 40% to 80% result in 20~30% and 2 times increase of $G_{max}$, respectively. It means that the gypsum content, that is cementation level, is the most influential factor on the $G_{max}$ of cemented sand. In addition, the effect of relative density on $G_{max}$ was more apparent on cemented sand than uncemented one.

• Resources Recycling
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• v.28 no.1
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• pp.23-31
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• 2019

Cementation is one of economical and efficient recycling method precipitating the metal ion in solution by adding another active metal. In this study for optimizing cadmium recovery efficiency, it was performed as a function of the effect of pH, temperature, particle size, and input amount of zinc in 0.1 M $CdSO_4$ solution and Ni-Cd battery leaching solutions, respectively. The particle size of zinc and temperature were key factors for Cd cementation and it was confirmed that the input amount of 2.6 of Zn/Cd ratio using granular-type zinc was optimal condition for selective Cd recovery efficiency at $25^{\circ}C$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.89-98
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• 2006

In this study, the iron and aluminium electrode was put in marine clay which was taken from south coast in Korea to increase the undrained shear strength by inducing the densification and cementation between clay particles and precipitation which was developed by electrode decomposition. For raising the cementation rate and reducing treatment time, high electric current( 2.5A) was applied in each electrode at semi-pilot scale soil box with marine clay. After the tests, the undrained shear strength was measured at designated points using cone penetration test device and sampling was conducted simultaneously in order to measure water content, pH and electric conductivity which would be the key for configuring the cementation effects indirectly. The iron electrode decomposition test results show that the water content adjacent to anode section decreased in 35% and increased in 13% at cathode section. The measured shear strength however, was increased considerably comparing to initial shear strength because of cementation effect between iron ions and soil particles. In case of aluminium electrode decomposition test, the distribution of measured shear strength and degree of improvement were more homogeneous than iron electrode decomposition test.

• The Journal of the Korean bone and joint tumor society
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• v.10 no.2
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• pp.71-78
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• 2004

Purpose: The purpose of this study is to investigate the characteristic of recurred giant cell tumor after bony curettage and cementation, and to review a way to prevent the recurrence. Materials and Methods : Thirty seven cases were analyzed, which were pathologically diagnosed giant cell tumor after diagnostic biopsy or surgical excision, followed by curative curettage, burring and cementation. Location, character, and time interval to recurrence were reviewed. Results: Thirteen out of thirty seven analyzed cases(35%) showed recurrence after primary curettage and cementation. The mean interval to recurrence was sixteen months(5 months to 43 months). Most of recurrence happened within the first two years except two cases. Among the recurred cases, eleven showed recurrence in the vicinity of window area. Two cases recurred in the depth of bone marrow, where cementation was made. The advantage of curettage and cementation is the immediate stability of the operation site, early rehabilitation, and early detection of recurrence. Furthermore, cementation is beneficial in that the cement-producing heat can eradicate the residual tumor burden. In this study, 85% of cases with insufficient curettage (for example, in cases where too small surgical window was made, or where there were anatomical difficulty in approaching the target tumor burden) showed recurrence. Conclusion: Bony curettage, burring and cementation is widely used as the primary curative modality for giant cell tumor. A few other modalities such as chemical cautery using phenol and $H_2O_2$; cryotherapy; and anhydroalcohol have also been introduced, but the benefit of these are still questionable. For some cases that relatively small surgical window was made due to anatomically complicated structures (such as ligament insertion or origin site) over the target tumor burden, unsatisfactory curettage and burring was made. This study showed high chance of recurrence after unsatisfactory curettage, and 85% of recurrence developed in the vicinity of the small window area. Most of the recurrence occurred within the first two years. It is concluded that sufficient window opening, extensive curettage and eradicative burring are key factors to prevent recurrence. Also, it should be reminded that careful and close observation should be made for at least the first two years after initial treatment for early detection of recurrence.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.19.1-19.1
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• 2009

Open-cell Ni-Cr and Ni-Cr-Al(with gamma/gamma prime microstructure typical of Bi-base super alloys) foams are manufactured by pack-cementation at $1000{\boxplus}$degrees C, followed by homogenization at $1200{\boxplus}C$. The resulting alloyed foams retain the low relative densities (less than 3.5 wt.%). The oxidation behavior of Ni-Cr foams turns out to be identical to that of bulk Ni-Cr alloys, after taking into account the foam's higher surface area. The room-temperature compressive behavior of the Ni-Cr and Ni-Cr-Al is compared to model predictions. Additionally, the foam creep behavior, measured between 680 and $825{\boxplus}C$ in the stress range of 0.1-0.3 MPa, compared to two analytical models, namely strut compression and strut bending as high-temperature deformation modes.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.619-626
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• 2005

This work aims at studing the stress-strain-strength behavior of an CSG(cemented sand and gravel) materials. An analysis of the mechanical behavior of the CSG is performed from the interpretation of results by unconfined compression test, large triaxial compression test in which the influence of both the degree of cementation and age. For CSG, It was concluded that the characterristics of compression are direct measurment of the degree of cementation and age. In addition, hyperbolic model is adopted to express the relation between elastic moduli and cementation, age, confined stress in small strain. The results of the test show that clear correlation with each other