• Korean Journal of Veterinary Service
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• v.31 no.3
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• pp.415-423
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• 2008

This study examined the effects of the daily noise stress on body weight, feed intake and clinicopathological findings in Korean indigenous goats. A total of 14 male goats was divided into 2 groups (test and control) with same number (n=7), and exam was started 2 weeks later. This study composed 2 stages. First was noise stage i.e., noise (80-100 dB) inflicted on the test for 70 minutes each time (5 times/day), and have continued for 2 months. Second was no noise for 2 months. Body weight and daily gain in stress group was decreased compared with control group after imposing noise (first stage). However, these results were reversed after ceasing noise (second stage). Average daily feed intake was not significant different between two groups throughout the experimental periods. But, feed conversion ratio was lowerin control group than another. Clinicopathological findings including total protein, albumin, globulin, total bilirubin, total cholesterol, triglyceride, aspartate aminotransferase (AST), alanine aminotransferase (ALT), glucose, amylase, blood urea nitrogen (BUN), cortisol, total leucocytes and hemoglobin value showed no significant different between stress and control group.

• Computers and Concrete
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• v.29 no.1
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• pp.47-57
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• 2022

The increase in waste tires has brought serious environmental problems. Using waste tires rubber particles as aggregate in concrete can reduce pollution and decrease the usage of natural aggregate. The paper describes an investigation on flexural bearing capacity of self-compacting concrete (SCC) pavement slabs containing crumb rubber. Cyclic loading tests with different stress ratios and loading frequencies are carried out on SCC pavement slabs containing crumb rubber. Based on Paris Law and test data, the fatigue life of SCC pavement slab containing crumb rubber is discussed, and a revised mathematical model is established to predict the fatigue life of SCC pavement slab containing crumb rubber. The model applies to different stress ratios and loading frequencies. The fatigue life of SCC pavement slab containing crumb rubber is affected by the stress ratio and loading frequency. The fatigue life increases with the increase of stress ratio and loading frequency. Real-time acoustic emission (AE) signals in the SCC pavement slab containing crumb rubber under cyclic loading are measured, and the characteristics of crack propagation in the SCC pavement slab containing crumb rubber under different stress ratios and loading frequencies are compared. The AE signals provide abundant information of fracture process zone and crack propagation. The variation of AE ringing count, energy and b-value show that the fracture process of SCC pavement slab containing crumb rubber is divided into three stages.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.3
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• pp.85-93
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• 1991

To investigate the effect of the initial sediment concentration ($C_o$) and bed shear stress (${\tau}_b$) on the settling properties of silty mud, deposition experiments were conducted in a recirculating flume using silty mud sediment taken from the Youngkwang coast which is located in the eastern Yellow Sea. The relative concentration, $C/C_o$ (C=depth averaged concentration), and the relative equilibrium concentration, $C_{eq}/C_o$ ($C_{eq}$=depth averaged concentration in the equilibrium state), have been found to depend much more strongly on the bed shear stress than initial concentration, and to increase with increasing bed shear stress. The minimum value. ${\tau}_{bmin}$, and maximum value. ${\tau}_{bmax}$, of critical bed shear stress for deposition of the Youngkwang sediment were deduced to be $0.017N/m^2$ and $1.25N/m^2$, respectively, and these values depend strongly on the properties of sediment (grain size and mineralogy). Formulas for the relative concentration and apparent median settling velocity in the range of ${\tau}_b{\geq}{\tau}_{bmin}$ were deduced. The apparent median settling velocity was found to depend much more strongly on the bed shear stress than the initial concentration and to decrease exponentially with increasing bed shear stress.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1417-1431
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• 1994

In this study, shear strength characteristics of the Nak-Dong river sand in Taegu area are investigated by triaxial compression test, considering shear strain control velocity, relative density, and confining pressure. The results from Lade model and Modified Lade model are compared with the measured value in the laboratory test. The results by the change of shear strain control velocity, relative density, and confining pressure are as follows; 1) The stress limit, which can be Coulomb's law about the Nak-Dong river sand, have ranged 120~200 kpa at 0.08%/min and 120~150 kpa at 0.5%/min. These limits are smaller than that of the calcareous sand and the well-graded, quartz sand. 2) The parameters needed to Lade model and Modified Lade model are much affected by the strain control velocity and the relative density. Consequently, in the field, it is important to use parameters aptly after accurately understanding both the loading condition and subsoil condition. 3) Overall, the principal stress ratio obtained from constitutive model equations is not affected by the control velocity, but both the relative density and confining pressure affect the result of constitutive model equations. Consequently, the study on the various conditions about the relative density and confining pressure is needed to accurately predict the stress-strain behavior on the Nak-Dong river sand. 4) For the range of the used confining pressure in the study, the Lade model shows better agreements with the measured value than the Modified Lade model, comparing the measured value with the principal stress ratio at failure and the internal friction angle of failure envelope obtained from the Lade model and Modified Lade model.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.4
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• pp.30-37
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• 2015

iFLASH System is new structural floor system which consists of sandwich panels filled with nano-composite. The nano-composite has low specific gravity and high bonding strength with steel plates. The bonding strength is one of important factors for structural performance of iFLASH System and it can further be improved by surface preparation such as blast metal cleaning. However, using none blast steel plates is recommended since surface preparation generates additional fabrication time and cost. In this study, a bonding strength test and bending experiment were conducted to check feasibility of applying none blast steel plates to iFLASH System. Moreover, stress in bonding plane between steel plates and nano-composite was analytically evaluated by finite element method. Consequently, flexural capacity of the specimen was 11% higher than theoretically calibrated value and its flexural behavior was structurally efficient without defect of bonding.

• Journal of Environmental Science International
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• v.13 no.4
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• pp.359-365
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• 2004

The change of chlorophyll fluorescence parameters, O-J-I-P transients and psbA gene expression were investigated in the leaves of Crinum asiaticum var. japonicum on the natural condition in winter, in order to elucidate physiological responses of photosystem II (PS II) activity to winter stresses. The photochemical efficiencies of PS II, Fv/Fm, were significantly low in winter, contrary to its high value in summer. The values of I -qN and I-qP were lower in midday than at dawn or night both in summer and winter, although their decrease in midday was less in winter than in summer. In the O-J-I-P transients, the fluorescence intensity of J, I, P-step decreased remarkably depending on temperature drop in winter. And the D I reaction center protein of PS II decreased in late winter more than in early winter, concomitantly with relatively high content of description products of psbA gene in midday. These results indicate that low temperature in winter causes irreversible damage to PS II and subsequently leads to cell death.

• Environmental Analysis Health and Toxicology
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• v.21 no.2 s.53
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• pp.165-172
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• 2006

The backs with a hair cut of 6-week-old healthy ICR male mice were once exposed to a dose of $400mJ/cm^2$ UVB. An acute dermal inflammation was observed, and the inflamed skins were almost completely cured after 6 days of the exposure. At 24 hours after exposure, the epidermal keratinocytes showed a cell-membrane damage with the destruction of intercellular junctions, agglutination of tonofilaments within the cytoplasm and nucleus damage. The activity of XO showed a significant increase (p<0.05) in up to 144 hours. The activities of CAT and SOD showed a significant decrease (p<0.05) in up to 96 hours, but they were not significantly different from the normal value at 144 hours. The GST activity was significantly decreased (p<0.01) in up to 96 hours, not so at 24 hours. However, that was not significantly different from the normal value at 144 hours. There was a significant decrease (p<0.01) in the contents of TBARS at 48 and 96 hours, without any significant difference at 144 hours. While the content of GSH was significantly lower (p<0.05) at 24 hours, that was not significantly different thereafter up to 144 hours from the normal value. Therefore, it is assumed that skin damage with a dose of $400mJ/cm^2$ UVB irradiation might be caused by the oxidative stress which was resulted from the unbalance of oxygen fret radical generating and scavenging enzymes.

• Environmental Analysis Health and Toxicology
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• v.26
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• pp.10.1-10.7
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• 2011

Objects: Chironomus riparius, a non-biting midge (Chironomidae, Diptera), is extensively used as a model organism in aquatic ecotoxicological studies, and considering the potential of C. riparius larvae as a bio-monitoring species, little is known about its genome sequences. This study reports the results of an Expressed Sequence Tags (ESTs) sequencing project conducted on C. riparius larvae using 454 pyrosequencing. Method: To gain a better understanding of C. riparius transcriptome, we generated ESTs database of C.ripairus using pyrosequencing method. Results: Sequencing runs, using normalized cDNA collections from fourth instar larvae, yielded 20,020 expressed sequence tags, which were assembled into 8,565 contigs and 11,455 singletons. Sequence analysis was performed by BlastX search against the National Center for Biotechnology Information (NCBI) nucleotide (nr) and uniprot protein database. Based on the gene ontology classifications, 24% (E-value${\leq}1^{-5}$) of the sequences had known gene functions, 24% had unknown functions and 52% of sequences did not match any known sequences in the existing database. Sequence comparison revealed 81% of the genes have homologous genes among other insects belonging to the order Diptera providing tools for comparative genome analyses. Targeted searches using these annotations identified genes associated with essential metabolic pathways, signaling pathways, detoxification of toxic metabolites and stress response genes of ecotoxicological interest. Conclusions: The results obtained from this study would eventually make ecotoxicogenomics possible in a truly environmentally relevant species, such as, C. riparius.

• Korean Journal of Environmental Agriculture
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• v.28 no.4
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• pp.397-402
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• 2009

In Korea, salt stress is one of the major problems limiting crop production and eco-environmental quality in greenhouse soil. The objective of this study was to evaluate the effectiveness of organic residues (Chinese milk vetch, maize stalk, rice straw, and rye straw) for reducing salt activity in greenhouse soil. Organic residues was incorporated with salt-accumulated soil (EC, 3.0 dS $m^{-1}$) at the rate of 5% (wt $wt^{-1}$) and the changes of electrical conductivity (EC) was determined weekly for 8 weeks under incubation condition at $30^{\circ}C$. The EC, microbial biomass carbon (MBC), and water soluble ions in soil was strongly affected by C/N ratio of organic residues. After 8 weeks incubation, the concentration of water soluble $NO_3{^-},\;Ca^{2+}$, and $Mg^{2+}$ was significantly decreased in organic residues having high C/N ratio (maize stalk, rice straw, and rye straw) incorporated soil compared to organic residues having lower C/N ratio (Chinese milk vetch) incorporated soil. The EC value in Chinese milk vetch incorporated soil was higher than control treatment. In contrast, maize stalk, rice straw, and rye straw amended soil was highly decreased the EC value compared to control and Chinese milk vetch applied soil after 4 weeks incubation. Our results indicated that incorporation of organic residues having high C/N ratio (>30) could reduce salt activity resulting from reducing concentration of water soluble ions.

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1487-1494
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• 2012

This study has been carried out to verify curative effect of lavender and lawn, a green space composition factor. Thus, the physiological index value of blood pressure, heart rate and salivary amylase were measured with object of 16 women in their 20~30s for stress relaxation effect at lavender garden and lawn square, and impression assessment upon SD method as for psychological value was performed in this study. And a survey was conducted on necessity and reason of urban green space with object of 345 men and women urban workers. As a result of variance analysis between groups and multi test of Turkey upon object place, the blood pressure was lowered the same at lavender garden and lawn square, and especially, high blood pressure was greatly lowered to 30 mmHG at lavender garden. On the other hand, low blood pressure group showed the tendency of a little increasing at the same places. And for the pulse, there was difference between high blood pressure group and normal group at the same places. To conclude, at lavender garden and lawn square the blood pressure was made to be lowered when it's high, and when it's low, the effect of returning to sound status, the function of increasing, was verified. In case of impression assessment upon SD method, the lawn square was assessed as resting place and lavender garden diversional place. And over 90% of urban workers responded to the green space's necessity and curative effect, diversion and resting place were adopted for the reason in high-ranking items. As above the green space pattern that urban workers require and curative effect of lavender garden and lawn square were verified. Therefore, the functional green space plan is required, which curative effect, diversion and resting place are considered, for the future green space plan design.