• Journal of the Chungcheong Mathematical Society
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• v.6 no.1
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• pp.113-130
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• 1993

In this paper, we introduce certain subgroups $E^{Rel}_n$ (X, Y, K, G) of the relative homotopy groups ${\sigma}_n$(X, Y, K, G) of a transformation group and examine the algebraic properties of these groups.

• Journal of the Chungcheong Mathematical Society
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• v.5 no.1
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• pp.9-21
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• 1992

We define a certain subgroup $E_n$ (X, K, G) of the relative homotopy groups of a transformation group ${\sigma}_n$(X, K, G). The algebraic properties of these groups are examined.

• Honam Mathematical Journal
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• v.34 no.4
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• pp.495-504
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• 2012

Let G be a semialgebraic group and M a proper semi-algebraic G-set which is locally complete. In this paper we show that the orbit space M/G has a semialgebraic structure such that the orbit map is semialgebraic.

• Korean Journal of Crystallography
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• v.7 no.2
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• pp.196-200
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• 1996

The transformation processes from unit cell data, Miller indices and atomic coordinates of non-standard space groups to the ones of the standard space groups in monoclinic system and the calculation processes of their standard deviations have been shown and computerized. The computer programs can be applied to all the seven crystal systems.

• The Journal of Advanced Prosthodontics
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• v.11 no.1
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• pp.1-6
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• 2019

PURPOSE. The purpose of this in vitro study was to evaluate the effect of surface grinding and polishing procedures using high speed zirconia diamond burs with different grit sizes on the phase transformation and flexural strength of zirconia. MATERIALS AND METHODS. Forty disc shape specimens ($15{\times}1.25mm$) with a cylindrical projection in the center of each disc ($1{\times}3mm$) were fabricated with 3Y-TZP (Prettau, Zirkonzahn, Italy). The specimens were divided into 4 groups (n=10) according to the grinding and polishing procedures: Control group - grinding (coarse-grit diamond bur), Group 1 - grinding (coarse-grit diamond bur) + polishing, Group 2 - grinding (fine-grit diamond bur) + polishing, and Group 3 - grinding (fine grit diamond bur). Each specimen was analyzed by 3D-OM, XRD analysis, and biaxial flexural strength test. RESULTS. Based on the surface morphology by 3D-OM images, polished specimens showed smoother surface and lower roughness value (Ra). In the result of XRD analysis, partial phase transformation from tetragonal to monoclinic zirconia occurred in all groups. Control group, ground with a coarse grit diamond bur, showed more $t{\rightarrow}m$ phase transformation and lower flexural strength than Groups 1 and 2 significantly. CONCLUSION. The flexural strength in all specimens after grinding and polishing showed over 500 MPa, and those were clinically acceptable. However, grinding with a coarse grit diamond bur without polishing induced the phase transformation and low strength. Therefore, surface polishing is required for the occlusal adjustment using a high speed zirconia diamond bur to reduce the phase transformation and to prevent the decrease of flexural strength of zirconia.

• Journal of the Chungcheong Mathematical Society
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• v.16 no.1
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• pp.73-79
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• 2003

A subgroup S(X, ${\gamma}$) of the group of automorphisms of a universal minimal transformation group is introduced and a necessary and sufficient condition for two subgroups to be identical is obtained.

• Journal of applied mathematics & informatics
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• v.8 no.1
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• pp.273-283
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• 2001

We introduce sums and joins of T-fuzzy transformation semi-groups and investigate their algebraic structures.

• Journal of the Chungcheong Mathematical Society
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• v.4 no.1
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• pp.103-113
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• 1991

Some properties of a path space and the fundamental group ${\sigma}(X,x_0,G)$ of a topological transformation group (X, G, ${\pi}$) are described. It is shown that ${\sigma}(X,x_0,H)$ is a normal subgroup of ${\sigma}(X,x_0,G)$ if H is a normal subgroup of G ; Let (X, G, ${\pi}$) be a transformation group with the open action property. If every identification map $p:{\Sigma}(X,x,G)\;{\longrightarrow}\;{\sigma}(X,x,G)$ is open for each $x{\in}X$, then ${\lambda}$ induces a homeomorphism between the fundamental groups ${\sigma}(X,x_0,G)$ and ${\sigma}(X,y_0,G)$ where ${\lambda}$ is a path from $x_0$ to $y_0$ in X ; The space ${\sigma}(X,x_0,G)$ is an H-space if the identification map $p:{\Sigma}(X,x_0,G)\;{\longrightarrow}\;{\sigma}(X,x_0,G)$ is open in a topological transformation group (X, G, ${\pi}$).

• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.132-137
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• 2018

PURPOSE. The purpose of this study was to evaluate and compare three polishing systems on the surface roughness and phase transformation of monolithic zirconia. MATERIALS AND METHODS. 100 disk shaped specimens (10 mm diameter, 3 mm thickness) were fabricated from monolithic zirconia blocks. 20 specimens were left as a control group and remaining specimens were grinded by diamond bur to simulate the occlusal adjustments. Grinded specimens were randomly divided into 4 groups: group G (no polishing), group M (Meisinger, zirconia polishing kit), group E (EVE Diacera, zirconia polishing kit), and group P (EVE Diapol, porcelain polishing kit). Surface roughness was measured with profilometer and surface topography was observed with SEM. XRD analysis was performed to investigate the phase transformation. Statistical analysis was performed with one-way ANOVA and Tukey's post hoc tests at a significance level of P=.05. RESULTS. All polishing groups showed a smoother surface than group G. Among 3 polishing systems, group M and group E exhibited a smoother surface than the group P. However, no significant differences were observed between group M and group E (P>.05). Grinding and polishing did not cause phase transformations in zirconia specimens. CONCLUSION. Zirconia polishing systems created a smoother surface on zirconia than the porcelain polishing system. Phase transformation did not occur during the polishing procedure.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.15
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• pp.6005-6008
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• 2014

Aim: To compare recurrence rates of large loop excision of the transformation zone (LLETZ) with those of contour-loop excision of the transformation zone (C-LETZ) in the management of cervical intraepithelial neoplasia (CIN). Materials and Methods: The medical records of 177 patients treated consecutively by LLETZ and C-LETZ for CIN at Rajavithi Hospital between 2006 and 2009 were retrospectively reviewed. Results: Of the 87 women in the C-LETZ group, 2 cases (2.30%) had recurrence compared with 13 cases (14.4%) of the 90 women in the LLETZ group, the higher recurrence rate in the latter being statistically significant (p<0.05). Median times of follow up in the C-LETZ and LLETZ groups were 12 months and 14 months respectively (p>0.05). The C-LETZ group showed less intraoperative bleeding compared to the LLETZ group, but the rate of achievement of single specimens and positive margins were similar in the two groups. Conclusions: The present study demonstrated the superiority of C-LETZ over LLETZ in terms of efficacy; C-LLETZ is associated with a lower recurrence rate and also carries a smaller risk of intraoperative bleeding than LLETZ. The rotating technique still has a potential role in treating precancerous lesions of the cervix.