• KSCE Journal of Civil and Environmental Engineering Research
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• v.1 no.1
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• pp.53-68
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• 1981

Most clays under sustained load exhibit time-dependent deformation because of creep movement of soil particles and many investigators have attempted to relate their findings to the creep behavior of natural ground and to the long-term stability of slopes. Since the creep behavior of clays may assume a variety of forms depending on such factors as soil plasticity, activity and water content, it is difficult and complicated to analyse the creep behavior of clays. Rheological models composed of linear springs in combination with linear or nonlinear dashpots and sliders, are generally used for the mathematical description of the time-dependent behavior of soils. Most rheological models, however, have been proposed to simulate the behavior of secondary compression for saturated clays and few definitive data exist that can evaluate the behavior of non-saturated clays under the action of sustained stress. The clays change gradually from a solid state through plastic state to a liquid state with increasing water content, therefore, the rheological models also change. On the other hand, creep is time-dependent, and also the effect of thixotropy is time-function. Consequently, there may be certain correlations between creep behavior and the effects of thixotropy in compacted clays. In addition, the states of clay depend on water content and hence the height of the specimen under drained conditions. Futhermore, based on present and past studies, because immediate elastic deformation occurs instantly after the pressure increment without time-delayed behavior, the factor representing immediate elastic deformations in the rheological model is necessary. The investigation described in this paper, based on rheological model, is designed to identify the immediate elastic deformations and the effects of thixotropy and height of clay specimens with varing water content and stress level on creep deformations. For these purposes, the uniaxial drain-type creep tests were performed. Test results and data for three compacted clays have shown that a linear top spring is needed to account for immediate elastic deformations in the rheological model, and at lower water content below the visco-plastic limit, the effects of thixotropy and height of clay specimens can be represented by the proposed rheological model not considering the effects. Therefore, the rheological model does not necessitate the other factors representing these effects. On the other hand, at water content higher than the visco-plastic limit, although the state behavior of clays is visco-plastic or viscous flow at the beginning of the test, the state behavior, in the case of the lower height sample, does not represent the same behavior during the process of the test, because of rapid drainage. In these cases, the rheological model does not coincide with the model in the case of the higher specimens.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.4
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• pp.231-237
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• 1973

Eeffect of temperature (3-day or 7-day treatment under $15^{\circ}C$, $20^{\circ}C$ and $25^{\circ}C$) on chlorophyll, nitrogen and potassium content in the second leaf blade from top of IR667 line (Suwon 213 and 214) and leading local varieties (Jinheung and Paldal) was investigated at the end of nursery, maximum tillering and flowering stage using phytotron. 1. Chlorophyll content was higher in IR667 line than in the local at $25^{\circ}C$ but reversed at $20^{\circ}C$ or $15^{\circ}C$ and chlorophyll a/b value was always high in the local. 2. Chlorophyll content per fresh weight decreased with growth and low temperature effect was greater at the end of nursery and on chlorophyll a than on chlorophyll b. 3. Chlorophyll a/b value increases with the increase of chlorophyll content and the increasing rate of chl. a/b value per chlorophyll increment tends to decrease under unfavorable condition. This decrease is greater in low temperature sensitive IR667 than local varieties. 4. According to chlorophyll retention value IR667 line was weaker at low temperature. 5. The content of total nitrogen or soluble nitrogen (methanol soluble) was decreased by low temperature. 6. Chl. (a+b)/S-N value decreased with growth and seemed not to be greatly affected by temperature and always higher in the local. 7. Potassium content (total or methanol soluble) tends to decrease at low temperature and soluble K increased with chlorophyll content. 8. High yielding ability of IR667 seems to be attributable to its high chlorophyll content at high temperature and easy leaf discoloration by low temperature or by nitrogen depression of IR667 seems to be attributable to the low Chl./S-N value.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.2
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• pp.529-541
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• 2003

Yukmijihwang-tang has been widely used as an and-aging herbal medicine for hundred years in Asian countries. Numerous studies show that Yukmijihwangtang has anti-oxidative effect both in vivo and in vitro. It has been reported that Moutan Cortex Radicis extract (MCR) was the most effective herb in Yukmijihwang-tang on undifferentiated PC12 cells upon oxidative-stressed with hydrogen peroxide. The purpose of this study is to; 1) evaluate the recovery of neuronal damage by assessing the anti-oxidant effect of MCR on PC12 cells differentiated with nerve growth factor (NGF), 2) identify candidate genes responsible for anti-oxidative effect on differentiated PC12 cells by oligonucleotide chip microarray. PC12 cells, which were differentiated by treating with NGF, were treated without or with hydrogen peroxide in the presence or absence of various concentration of MCR. Cell survival was determined by using MTS assay. Measurement of intracellular reactive oxygen species (ROS) generation was determined using the H2DCFDA assay The viability of cells treated with MCR was significantly recovered from stressed PC12 cell. In addition, wide rage of concentrations of MCR shows dose-dependent inhibitory effect on ROS production in oxidative-stressed cells. Total RNAs of cells without treatment(Control group), only treated with H₂O₂ (stressed group) and treated with both H₂O₂ and of MCR (MCR group) were isolated, and cDNAs was synthesized using oligoT7(dT) primer. The fragmented cRNAs, synthesized from cDNAs, were applied to Affymetrix GeneChip Rat Neurobiology U34 Array. mRNA of Calcium/calmodulin-dependent protein kinase II delta subunit(CaMKII), neuron glucose transporter (GLUT3) and myelin/oligodendrocyte glycoprotein(MOG) were downregulated in Stressed group comparing to Control group. P2X2-5 receptor (P2X2R-5), P2X2-4 receptor (P2X2R-4), c-fos, 25 kDa synaptosomal attachment protein(SNAP-25a) and GLUT3 were downregulated, whereas A2 adenosine receptor (A2AR), cathechol-O-methyltransferase(COMT), glucose transporter 1 (GLUT1), EST223333, heme oxygenase (HO), VGF, UI-R-CO-ja-a-07-0-Ul.s1 and macrophage migration inhibitory factor (MIF) were upregulated in MCA group comparing to Control group. Expression of Putative potassium channel subunit protein (ACK4), P2X2A-5, P2X2A-4, Interferon-gamma inducing factor isoform alpha precursor (IL-18α), EST199031, P2XR, P2X2 purinoceptor isoform e (P2X2R-e), Precursor interleukin 18 (IL-18) were downregulated, whereas MOO, EST223333, GLUT-1, MIF, Neuronatin alpha, UI-R-C0-ja-a-07-0-Ul.s1, A2. adenosine receptor, COMT, neuron-specific enolase (NSE), HO, VGF, A rat novel protein which is expressed with nerve injury (E12625) were upregulated in MCR group comparing to Stressed group. The results suggest that decreased viability and AOS production of PC12 cell by H₂O₂ may be, at lease, mediated by impaired glucose transporter expression. It is implicated that the MCR treatment protect PC12 cell from oxidative stress via following mechanisms; improving glucose transport into the cell, enhancing expression of anti-oxidative genes and protecting from dopamine cytotoxicity by increment of COMT and MIF expression. The list of differentially expressed genes may implicate further insight on the action and mechanism behind the anti-oxidative effects of herbal extract Moutan Cortex Radicis.

• Journal of Life Science
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• v.23 no.4
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• pp.501-509
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• 2013

Formaldehyde (FA) is widely used in industries, and it is an indoor and outdoor pollutant. Exposure to FA may cause inflammation and respiratory oxidative stress. Studies have demonstrated that FA can cause cancer in animal models. During the regeneration process of injured starfish (Asterina pectinifera), several changes have been observed in the expression of cytokines. In particular, higher TGF-${\beta}1$ expression has been detected in arm cut starfish extract after eight days. The current study was designed to elucidate the in-vitro and the in-vivo pharmacological effects of starfish extract on FA exposure. We investigated the protective effects of intact starfish extract and arm cut starfish extract on an IMR-90 cell line and on mouse lung injury in response to FA exposure. In the presence of FA, inhalation of the arm cut starfish extract was associated with more promising cell proliferation, TNF-${\alpha}$, NF-${\kappa}B$ decrement, and $I{\kappa}-B{\alpha}$ increment. In the experimental group, the pulmonary structure of the arm cut starfish extract-treated group in the presence of FA exposure was similar to the control group, whereas the FA exposure group showed damage to the pulmonary structure. Moreover, the arm cut starfish extracts was more effective than the intact starfish extracts in terms of the expression of TNF-${\alpha}$, NF-${\kappa}B$, $I{\kappa}-B{\alpha}$, and surfactant protein A. The results obtained in this study demonstrate that arm cut starfish extracts are more effective in protecting pulmonary structure and function against FA exposure than intact starfish extracts.

• Korean Journal of Poultry Science
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• v.30 no.2
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• pp.83-90
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• 2003

This study was conducted to determine the effects of stocking density on performance and physiological responses of egg-type breeder layers in cages. A total of 264 Hy-Line Brown egg-type breeder layers at the age of 32 weeks were divided into 4 groups with 3 replicates of 22 birds (20 females, 2 males) per replicate and assigned to four stocking density treatments with 22 birds per cage with different sizes (980, 735, 640 and 560 $\textrm{cm}^2$/bird). The birds were fed the same experimental diet ad libitum for 12 weeks, and laying performance, egg and eggshell qualities, fertility and hatchability were determined. At the end of the experimental period, 9 birds were selected in each treatment in order to measure the scores of plumage condition. Antibody titers to Newcastle disease and infectious bronchitis were also determined. No significant differences were observed in laying performances, eggshell strength, Haugh unit, fertility and hatchability among the treatments. In birds housed 640 $\textrm{cm}^2$ per bird, eggshell thickness were significantly lower (P<0.05) than those of the other groups from 7 to 12 weeks. There was no significant difference in antibody titers to Newcastle disease. In birds housed 980 $\textrm{cm}^2$ per bird, antibody titers to infectious bronchitis were significantly (P<0.05) higher than those of the other groups. With increase in the level of stocking density, the scores of plumage condition were also significantly decreased (P<0.01). This study demonstrated that moderate increment of stocking density did not resulted in reduction in laying-performances of egg-type breeder layers. However, it seemed that the higher stocking density might give more stress to the birds from physical stimuli and thus were harmful environment causing higher mortalities compared to the lower ones.

• Korean Journal of Culture and Social Issue
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• v.15 no.1
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• pp.187-205
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• 2009

Based on the Motivational States Theory(MOST), the present research expanded and complemented Kim(2007)'s proposal to add the Life Satisfaction Expectancy Scale(LSES) to Diener et al's Satisfaction With Life Scale(SWLS) to measure subjective well-being(SWB). In the present study, the Life Satisfaction Motivation Scale(LSMS) was introduced to measure the strength of motivation for life satisfaction in general. Two hundred and eighty six college students participated in this study. Factor analyses revealed a two-factor structure, with the factors corresponding to life satisfaction and life satisfaction expectancy. Measures of internal and temporal reliability show the LSMS to be a good complement for the measure of SWB(The LSMS showed high internal and test-retest reliability). It was found that the addition of the LSES provided a significant increment in predictive power over the SWLS in the prediction of various factors related with well-being prediction. Exceptionally, in the prediction of anger the LSMS had the most predictive power. There were some differences between male and female students in the correlations among life satisfaction, life satisfaction expectancy and life satisfaction motivation and well-being-related factors. The merits of including LSES in the measurement of subjective well-being and the limitations of this study are discussed.