• Environmental Mutagens and Carcinogens
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• v.19 no.1
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• pp.46-55
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• 1999

To develop a chemopreventive strategy based on the different stages of premalignant lesions, we hypothesized that the inhibitory effect of chemopreventive agents is influenced by different promotion stages during carcinogenesis. DMBA-TPA-induced skin carcinogenesis was used with ICR mice and chlorophyllin (CHL) was applied as a chemopreventive agent. In vitro assay was performed with Salmonella typhi. TA100 to observe any anti-mutagenic activity of CHL against DMBA. Pre-initiation and pre-promotion effects of CHL were observed by CHL treatment before initiation and before promotion. To evaluate the inhibitory effect at different promotion stages, each group was divided into three subgroups after TPA promotion for 6, 18 and 24 weeks, respectively ; the first subgroup was immediately sacrificed after termination of TPA, the second subgroup was treated with CHL, and the third subgroup was sacrificed 8 weeks after termination of TPA without CHL treatment. The degrees of epithelial dysplasia, papilloma formation, and invasive carcinoma were observed histologically, and GST-Pi expression was observed immunohistochemically. ODC mRNA level was analyzed by reverse transcriptase-polymerase chain reaction. Results showed : CHL dose-dependently inhibited the mutation of Salmonella typhi. TA100; the incidence of epithelial dysplasia and papilloma formation was lower in pre-initiation and pre-promotion CHL-treated mice than DMBA-TPA-treated mice; no invasive carcinoma developed in pre-initiation CHL-treated groups, while 67% of DMBA-TPA treated mice had carcinomas; GST-Pi expression decreased when CHL was treated before initiation and before promotion; and when CHL was treated after termination of TPA application at 18 and 24- week-TPA promotion stages, respectively, the incidence of epithelial dysplasia and papilloma was markedly reduced compared to non-treated groups. When comparing the incidence of epithelial dysplasia and papilloma between the immediately-sacrificed subgroup and the non-treated group with a waiting period, we speculated that the 18-week-TPA promotion stage might belong to the promoter-independent progression stage. At the 18-week-TPA promotion stage, the level of ODC mRNA in the CHL-treated group was clearly reduced to the level of normal tissue. Taking these results together, CHL showed both anti-initiation and anti-promotion effects, while the inhibitory effect of CHL was prominent in the 18-week-TPA promotion stage. However, CHL seems to be incapable of completely blocking the progression in the 24-week-TPA promotion stage.

• The Journal of Advanced Prosthodontics
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• v.11 no.6
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• pp.324-330
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• 2019

PURPOSE. The aim of the study was to evaluate and compare the fracture resistance and modes of fracture of monolithic zirconia crowns with two preparation designs. MATERIALS AND METHODS. Forty human maxillary first premolar teeth were extracted for orthodontic purposes and divided into two main groups (n=20): Group A: monolithic traditional zirconia; Group B: monolithic translucent zirconia. The groups were further subdivided into two subgroups (n=10): (A1, B1) shoulder margin design; (A2, B2) feather-edge margin design. Teeth were prepared with either a 1 mm shoulder margin design or a feather-edge margin design. The prepared teeth were scanned using a digital intraoral scanner. The crowns were cemented using self-adhesive resin cement. All cemented teeth were stored in water for 7 days and thermocycling was done before testing. All samples were subjected to compressive axial loading until fracture. The fractographic analysis was done to assess the modes of fracture of the tested samples. RESULTS. The highest mean values of fracture resistance were recorded in kilo-newton and were in the order of subgroup A1 (2.903); subgroup A2 (2.3); subgroup B1 (1.854) and subgroup B2 (1.523). One-way ANOVA showed a statistically significant difference among the 4 subgroups. Concerning modes of fracture, the majority of samples in subgroups A1 and B1 were fracture of restoration and/or tooth, while in subgroups A2 and B2, the majority of samples fractured through the central fossa. CONCLUSION. Even though all the tested crowns fractured at a higher level than the maximum occlusal forces, the shoulder margin design was better than the feather-edge margin design and the monolithic traditional zirconia was better than the monolithic translucent zirconia in terms of fracture strength.

• Korean Journal of Mathematics
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• v.9 no.2
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• pp.149-156
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• 2001

We characterize some properties of $t$-fuzzy groups and $t$-fuzzy invariant groups and represent every subgroup S of a group X using the level set of $t$-fuzzy group constructed from S.

• Communications of the Korean Mathematical Society
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• v.11 no.3
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• pp.633-641
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• 1996

Let $P_J$ be a standard parabolic subgroup of a Chevalley group G and $U_J$ the unipotent radical of $P_J$. In this paper, we find a certain partition of the set of roots corresponding to root subgroups generating $U_J$ and investigate some properties of the partition.

• Journal of Korean society of Dental Hygiene
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• v.16 no.3
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• pp.409-415
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• 2016

Objectives: The purpose of the study is to investigate the correlation between stress and oral health in some high school students. Methods: The subjects were 224 students from three high schools in Daejeon, Daecheon, and Incheon. from November to December, 2015. A self-reported questionnaire was filled out from November to December, 2015. The questionnaire consisted of general characteristics of the subjects, awareness toward stress, stress-coping pattern, oral health-related quality of life and oral health care. Data were analyzed by SPSS 18.0 program. Results: In the analysis of academic stress level by the general characteristics and stress level, higher stress group showed higher experience in stress expectation(high group 16.43, subgroup 9.21), internal stress(high group 13.97, subgroup 6.16), expression type stress(high 10.06, sub-4.95). The higher stress group had emotional stress management in stress-coping pattern and less experience in difficulty of tooth brushing, chewing discomfort, and oral health-related quality of life management(p<0.001). Conclusions: The stress had a negative impact on the oral health related quality of life. The high school students should be able to manage the physical and mental stress. It is necessary to provide the continuous oral health care management against the stress by the dental hygienists.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.2
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• pp.154-161
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• 2014

We discuss some interesting sublattices of interval-valued fuzzy subgroups. In our main result, we consider the set of all interval-valued fuzzy normal subgroups with finite range that attain the same value at the identity element of the group. We then prove that this set forms a modular sublattice of the lattice of interval-valued fuzzy subgroups. In fact, this is an interval-valued fuzzy version of a well-known result from classical lattice theory. Finally, we employ a lattice diagram to exhibit the interrelationship among these sublattices.

• Journal of Korean Society for Quality Management
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• v.19 no.2
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• pp.172-180
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• 1991

The null hypothesis being tested by $the{\bar{X}}$ control chart is that the process is in control at a quality level ${\mu}o$. An ${\bar{X}}control$ chart is a tool for detecting process average changes due to assingnable causes. The major weakness of $the{\bar{X}}$ control chart is that it is relatively insensitive to small changes in the population mean. This paper presents one way to remedy this weakness is to allow each plotted value to depend not only on the most recent subgroup average but on some of the other subgroup averages as well. Two approaches for doing this are based on (1) moving averages and (2) exponentially weighted moving averages of forecasting method.

• Journal of the Korean Mathematical Society
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• v.60 no.1
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• pp.115-141
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• 2023

We study a class of left-invariant pseudo-Riemannian Sasaki metrics on solvable Lie groups, which can be characterized by the property that the zero level set of the moment map relative to the action of some one-parameter subgroup {exp tX} is a normal nilpotent subgroup commuting with {exp tX}, and X is not lightlike. We characterize this geometry in terms of the Sasaki reduction and its pseudo-Kähler quotient under the action generated by the Reeb vector field. We classify pseudo-Riemannian Sasaki solvmanifolds of this type in dimension 5 and those of dimension 7 whose Kähler reduction in the above sense is abelian.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.2
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• pp.234-239
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• 2012

The objective of this study was to evaluate the effects of forage level and oil supplement on selected strains of rumen bacteria believed to be involved in biohydrogenation (BH). A continuous culture system consisting of four fermenters was used in a $4{\times}4$ Latin square design with a factorial arrangement of treatments, with four 10 d consecutive periods. Treatment diets were: i) high forage diet (70:30 forage to concentrate (dry matter basis); HFC), ii) high forage plus oil supplement (HFO), iii) low forage diet (30:70 forage to concentrate; LFC), and iv) low forage plus oil supplement (LFO). The oil supplement was a blend of fish oil and soybean oil added at 1 and 2 g/100 g dry matter, respectively. Treatment diets were fed for 10 days and samples were collected from each fermenter on the last day of each period 3 h post morning feeding. The concentrations of vaccenic acid (t11C18:1; VA) and c9t11 conjugated linoleic acid (CLA) were greater with the high forage diet while the concentrations of t10 C18:1 and t10c12 CLA were greater with the low forage diet and addition of oil supplement increased their concentrations at both forage levels. The DNA abundance of Anaerovibrio lipolytica, and Butyrivibrio fibrisolvens vaccenic acid subgroup (Butyrivibrio VA) were lower with the low forage diets but not affected by oil supplement. The DNA abundance of Butyrivibrio fibrisolvens stearic acid producer subgroup (Butyrivibrio SA) was not affected by forage level or oil supplement. In conclusion, oil supplement had no effects on the tested rumen bacteria and forage level affected Anaerovibrio lipolytica and Butyrivibrio VA.

• The Korean Journal of Ecology
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• v.18 no.1
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• pp.121-136
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• 1995

The forest vegetation on Mt. Ch’ongnyang was investigated for phytosociological analysis of the vegetation types and interspecific association. The forest was classified into seven vegetation units; A: Quercus Mongolica community, A-1: Group of Quercus variabilis, A-1-a: Subgroup of Pinus densiflora, A-1-b: Typical subgroup, A-2: Group of Aconitum trilobum, A-3: Group of Quercus dentata, B: Zelkova serrata communty. The group of Quercus variabilis was distributed on southeast- and southwest-facing slopes in 400~830 m above the sea level, and organic matter in the soil was 3.36~4.67％. The group of Aconitum trilobum was distributed on northeast- and northwest-facing slopes in 650~830 m above the sea level, and organic matter in the soil was 7.18％. The group of Quercus dentata was distributed on southwest-facing solpes in the vicinity of 810 m above the sea level, and organic matter in the soil was 9.7％. The Zelkova serrata community was distributed in the vicinity of ravines, and organic matter in the soil was 7.6％. The contents of Mg and Ca, and electric conductivity in the Zelkova serrata community were relatively high, 11.82 me/100mg, and 11.27 me/100mg, 102.2 μ mos/cm, respectively. In the results of polar ordination, environmental gradient of axis Ⅰ and axis Ⅱwere correlated with moisture, inclination and azimuth, respectively. Group of Quercus variabilis has occurred in xeric, group of Aconitum trilobum in submesic, and the Zelrova serrata community in mesic sites. In the meantime the interspecific association analysis based on chi-square yielded three species groupings with high positive affinity(p<0.01), i.e.group Ⅰ consisted of 18 species, including Acer pseudo-sieboldianum, Ansliaea acerifolia, Aconitum trilobum and group Ⅲ consisted of 19 species, in cluding Zelrova serrata, Oplismenus undulatifolius, Acer truncatum var. barbinerve, respectively.