• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.400-408
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• 2003

Chloride ion inside concrete destroys the so-called passive film surrounding reinforcing bars inside concrete so that the so-called salt attack accelerates corrosion which is the most critical factor for durability as well as structural safety of reinforced concrete structures. Recently, as a solution of the salt attack, the ground granulated blast-furnace slag(GGBFS) have been used as binder or blended cement more extensively. In this paper, characteristics of chloride ion diffusion for the GGBFS concrete, which is known to possess better resistance to damage due to the chloride ion penetration than ordinary portland cement(OPC) concrete possesses, are analyzed and a chloride ion diffusion model for the GGBFS concrete is proposed by modifying an existing diffusion model for the OPC concrete. The proposed model is verified by comparing diffusion analysis results using the model accelerated chloride penetration test results for concrete specimens as well as field test results for an RC bridge pier. Then, an optimal resistance condition to chloride penetration for the GGBFS concrete is obtained according to degrees of fineness and replacement ratios of the GGBFS concrete. The result shows that the GGBFS concrete has better resistance to chloride ion penetration than OPC concrete has and the resistance is more affected by the replacement ratio than the degree of fineness of the GGBFS.

• Journal of Environmental Science International
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• v.4 no.4
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• pp.21-21
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• 1995

The effects of plant hormones (NAA, $GA_3$ and BA) and light qualities (white, red, green and blue light) on the changes of reducing sugar contents and invertase isozyme activities in leaves of maize (Zea mars L.) and mung bean (Phseolw radiatus L.) seedlings were investigated. NAA accelerated the increase of reducing sugar contents and invertase isozyme activities, on the contrary, $GA_3$ had little effect in the accumulation of reducing sugar and in the increase of enzyme activities from the leaves of maize and mung bean seedlings. On the other hand, BA accelerated an increase in the activities of the invertase isozyme from the leaves of mung bean seedlings whereas it had little effect in the increase of the enzyme activities from those of maize seedlings. The accumulation of reducing sugar in leaves of both seedlings was promoted by red light irradiation compared to white light irradiation, while the activities of the enzyme were little affected by various light Qualities. In the simultaneous applications of plant hormone and light quality, NAA with white light was very effective in the increase of reducing sugar contents and the enzyme activities from the leaves of mung bean seedlings, whereas NAA application with blue light showed a prominent enhancement in the reducing sugar contents and the enzyme activities from those of maize seedlings. These results suggest that plant hormone, particularly NAA, may be a more important factor than various light Qualities in the stimulation of invertase activity.

• Journal of Environmental Science International
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• v.4 no.4
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• pp.323-333
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• 1995

The effects of plant hormones (NAA, $GA_3$ and BA) and light qualities (white, red, green and blue light) on the changes of reducing sugar contents and invertase isozyme activities in leaves of maize (Zea mars L.) and mung bean (Phseolw radiatus L.) seedlings were investigated. NAA accelerated the increase of reducing sugar contents and invertase isozyme activities, on the contrary, $GA_3$ had little effect in the accumulation of reducing sugar and in the increase of enzyme activities from the leaves of maize and mung bean seedlings. On the other hand, BA accelerated an increase in the activities of the invertase isozyme from the leaves of mung bean seedlings whereas it had little effect in the increase of the enzyme activities from those of maize seedlings. The accumulation of reducing sugar in leaves of both seedlings was promoted by red light irradiation compared to white light irradiation, while the activities of the enzyme were little affected by various light Qualities. In the simultaneous applications of plant hormone and light quality, NAA with white light was very effective in the increase of reducing sugar contents and the enzyme activities from the leaves of mung bean seedlings, whereas NAA application with blue light showed a prominent enhancement in the reducing sugar contents and the enzyme activities from those of maize seedlings. These results suggest that plant hormone, particularly NAA, may be a more important factor than various light Qualities in the stimulation of invertase activity.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1067-1072
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• 2003

The electrical stability of the varistor ceramics composed of Zn-Pr-Co-Cr-Dy oxides-based varistors was investigated at 0.0∼2.0 mol% Dy$_2$O$_3$ content under DC accelerated aging stress. The ceramic density was increased up to 0.5 mol% Dy$_2$O$_3$ whereas further addition of Dy$_2$O$_3$ decreased sintered ceramic density. The density sailently affected the stability due to the variation of conduction path. The nonlinearity of varistor ceramics was greatly improved above 45 in the nonlinear exponent and below nearly 1.0 ${\mu}$A by incorporating Dy$_2$O$_3$. Under 0.95 V$\_$1mA/150$^{\circ}C$/24 h stress state, the varistor ceramics doped with 0.5 mol% Dy$_2$O$_3$ exhibited the highest electrical stability, in which the variation rates of varistor voltage, nonlinear exponent, and leakage current were -0.9%, -14.4%, and +483.3%, respectively. The variation rates of relative permittivity and dissipation factor were +7.1% and +315.4%, respectively. The varistors with further addition of Dy$_2$O$_3$ exhibited very unstable state resulting in the thermal runaway due to low density.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.4
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• pp.21-27
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• 2024

In this study, the corrosion density of tendon was evaluated with changing chloride and hydroxide ions. To simulate an accelerated corrosive environment, wet sand was used instead of concrete, and the tests were conducted considering three levels of chloride concentration (0.0, 0.125, and 0.250mol/l ) and three [Cl^-]/[OH^-] ratios (0.3, 0.6, and 0.9). The corrosion density was measured to 5.13 µA/cm² at 0.0mol/l and increased with the chloride concentration. Additionally, no significant differences were observed over 0.125mol/l of chloride concentration. When [OH^-] increased with a given chloride concentration (0.125mol/l), the corrosion density decreased linearly, showing effective control of corrosion density even at high chloride concentrations. Notably, the measured corrosion amounts were lower than those under of 0.0mol/l condition. Furthermore corrosion density and influencing parameters were normalized with the maximum and minimum results, and the relation between them was analyzed.

• Journal of Soil and Groundwater Environment
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• v.13 no.6
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• pp.62-71
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• 2008

Soil quality standards (SQS) are necessary to protect the human health and soil biota from the exposure to soil pollutants. The current SQS in Korea contain only sixteen substances, and it is scheduled to expand the number of substances. Chemical ranking and scoring (CRS) system is very effective to screen the priority chemicals for the future SQS in terms of their toxicity and exposure potential. In this study, several CRS systems were extensively compared to propose the assessment factors that required for the screening of soil pollutants The CRS systems considered in this study include the CHEMS-1 (Chemical Hazard Evaluation for Management Strategies), SCRAM (Scoring and Ranking Assessment Model), EURAM (European Union Risk Ranking Method), ARET (Accelerated Reduction/Elimination of Toxics), CRSKorea, and other systems. The additional assessment factors of CRS suitable for soil pollutants were suggested. We suggest soil adsorption factor as an appropriate factor of CRS system to consider chemical transport from soil to groundwater. Other factors such as soil emission rate and cases of accident of soil pollutants were included. These results were reflected to screen the priority chemicals in Korea, as a part of the project entitled ‘Setting the Priority of Soil Contaminants'.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.102-102
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• 2002

Heparin-bindin epidermal growth factor (HB-EGF) is one of the EGF family to be expressed at the time of implantation in the mouse uterus. Although HB-EGF has been shown to stimulate the development of embryo and uterus in the mouse, its correlation between cell adhesion molecules remains undefined. Integrin $\alpha$$_{ν}$$\beta$$_3$, one of the cell adhesion molecules, is an important mediator of cell-substratum and cell-cell adhesion in implantation. In the present studies, we investigated the effects of HB-EGF on the embryonic development, initiation of implantation and expression of integrin $\alpha$$_{ν}$$\beta$$_3$ in in vitro culture, blocking of HB-EGF, RT-PCR and immunofluores cence analysis. The results showed that HB-EGF significantly improved the developmental rate of hatched embryos (24.1%, p<0.01) and outgrowth embryos (42.5%, p<0.01). On the other hand, this growth factor showed no offset before the hatching embryonic stage. Analysis of RT-PCR showed that HB-EGF upregulated the expression level of integrina $\alpha$$_{ν}$$\beta$$_3$ subunit genes on the preimplantation embryo and outgrowth of blastocyst (120hr and 144hr after hCG injection). Immunofluorescence analysis showed that the integrin $\alpha$$_{ν}$$\beta$$_3$ subunits localized at the pericellular borders and cell-cell contact areas. Increase in fluorescence intensity was observed in the HB-EGF treated embryos. Intrauterine injection of an anti-HB-EGF antiserum at day 3 significantly decreased the number of implantation sites (14.4, p<0.01) and significantly increased the number of recovered embryos(6.4, p<0.05) at day 5. From these results, it imply that HB-EGF improve the embryo development and accelerated the expression of integrin $\alpha$$_{ν}$$\beta$$_3$ in the preimplantation mouse embryos.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.4
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• pp.281-287
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• 2017

Stress in skin plays a significant role in both the direct/indirect regulation of cellular processes occurring in hair, which in turn affect the hair cycle. However, experimental data regarding the effects of stress-related corticotropin releasing factor (CRF) released by stress on the apoptotic process involved in hair is limited. Therefore, we investigated the acceleration of early-stage apoptosis induced by atopy-related stress using a 2,4-dinitrochlorobenzene NC/Nga mice model. Expression of CRF, its related proteins, annexin V, and mitochondrial dysfunction were measured by immunohistochemical analyses. Atopic stress strongly stimulated stress hormones response, such as CRF and adrenocorticotropic hormone, in outer epithelial sheath of the hair. Moreover, its stress induced mitochondrial damage and early-stage apoptosis of cells in hair root. These findings suggest that hair damage due to apoptosis in atopy model is accelerated in a high CRF environment. Importantly, the effect of stress-related CRF on apoptosis processes involved in atopy dermatitis-related hair loss, suggests that the CRF-regulating development or maintenance materials may provide effective therapeutic strategies for hair health.

• The Plant Pathology Journal
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• v.22 no.3
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• pp.271-277
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• 2006

The interaction effects of ozone $(O_3)$ and anthracnose (Colletotrichum acutatum) disease were examined in green fruits and seedlings of pepper (Capsicum annuum). Pre-treatment with $(O_3)$ as a factor causing predisposition to the disease prior to infection was investigated in green fruits and stems using an $(O_3)$ concentration of 150 nL/L, which is easily reached in summer in Korea. $(O_3)$ treatment increased antioxidative responses in pepper foliar tissues, and defense against anthracnose was examined in fruits and stems. Anthracnose severity on stems of the $O_3-treated$, ozone-sensitive 'Dabotop' cultivar was always lower than that on untreated plants, but the difference was not always significant (p=0.147). Significantly lower anthracnose severity was found on $O_3-treated$ green 'Dabotop' fruits as compared to untreated green fruits in three of eight replicate experiments. In contrast, hypersensitive responses in 03treated seedlings were significantly accelerated compared to those in untreated seedlings by about 7.8 h (p<0.001). This confirmed previous evidence of increased transcription of plant defense genes with $(O_3)$ treatment. $(O_3)$ treatment significantly decreased chlorophyll concentrations in the leaves in four replicate experiments (p<0.01). $(O_3)$ increased hypersensitive responses in the leaves of pepper seedlings, but this increase did not contribute to the control of anthracnose severity on fruits. Antioxidant reactions to $(O_3)$ were limited to chlorosis and changes in hypersensitive responses in leaves.

• The Journal of Korean Association of Computer Education
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• v.16 no.2
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• pp.61-68
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• 2013

SNS is a social networking service that helps people to have a two-way communication, manage their personal relationships and share information. The domestic and international SNS markets have attained a steady growth, and their growth is being more accelerated recently. Under these circumstances, immature students are more likely to show negative cyber behavior. This study attempted to analyze the relationship between the use of SNS, motives of SNS use, the use of active SNS functions, SNS-dependency and views in SNS and negative SNS behaviors among elementary and middle school students. For this, negative cycber behaviors are classified into four stages depending on the severity, for each of which distribution of factors is investigated and the combination of factors to determine each stage is obtained through association rule analysis. As a result, it is found that 85% of the students rarely show negative cyber behaviors, stealing personal information and contacting with strangers are the most frequent negative behaviors, and students with a great dependency on SNS are highly probable to show negative behaviors.