• 대한기계학회논문집A
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• 제21권4호
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• pp.673-678
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• 1997

Stress wave propagations in an elastic half space to a normal point force of ramp type in time are analyzed. The governing equations are transformed by applying the Laplace and Hankel transforms with respect to time and radial distance. The inversion of Laplace transforms are performed by employing the Cagniard-de Hoop method, where the Rayleigh waves at surface are obtained by including the residue terms. The stress waves computed at the location very cose to the surface are shown to be almost identical to the surface waves obtained by the residue method except the Rayleigh wavefront. It is found that at the surface, the stresses are dominated by the Rayleigh waves, whose amplitudes increase linearly with time when time is very large. It is also found that in the interior part, the radial stress has a logarithmic singularity at the shear wavefront, while tangential stress shows no singularity.

• Plant Biotechnology Reports
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• 제4권1호
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• pp.75-83
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• 2010

Glycine betaine has been reported as an osmoprotectant compound conferring tolerance to salinity and osmotic stresses in plants. We previously found that the expression of betaine aldehyde dehydrogenase 1 gene (OsBADH1), encoding a key enzyme for glycine betaine biosynthesis pathway, showed close correlation with salt tolerance of rice. In this study, the expression of the OsBADH1 gene in transgenic tobacco was investigated in response to salt stress using a transgenic approach. Transgenic tobacco plants expressing the OsBADH1 gene were generated under the control of a promoter from the maize ubiquitin gene. Three homozygous lines of $T_2$ progenies with single transgene insert were chosen for gene expression analysis. RT-PCR and western blot analysis results indicated that the OsBADH1 gene was effectively expressed in transgenic tobacco leading to the accumulation of glycine betaine. Transgenic lines demonstrated normal seed germination and morphology, and normal growth rates of seedlings under salt stress conditions. These results suggest that the OsBADH1 gene could be an excellent candidate for producing plants with osmotic stress tolerance.

• 한국지반환경공학회 논문집
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• 제7권3호
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• pp.31-41
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• 2006

화강암 시료에서 절리면 시편의 크기효과를 연구하기 위해 6가지 크기의 인공절리 시편을 제작하여 직접전단시험을 수행하였다. 각기 다른 수직응력 0.29~2.65MPa과 절리면의 거칠기 파라미터에 대하여 최대전단응력, 잔류전단응력, 전단강성 및 팽창각이 이 연구를 위해 평가되었다. 거칠기 파라미터중 절리거�s계수(JRC)와 절리면의 압축강도(JCS)는 시편의 크기가 증가할수록 감소하였다. 시편의 절리면적이 $12.25cm^2$에서 $361cm^2$으로 증가할 경우 최대전단응력은 약 56~67%, 잔류전단응력은 18~44%까지 감소하였다. 또한 팽창각은 수직응력이 0.29 MPa일 때 $27^{\circ}$, 2.65 MPa일 때 $6^{\circ}$의 변화를 보였다. JRC 크기효과를 고려한 전단강도 관계식이 Barton의 경험식과 비교되었다.

• 동의신경정신과학회지
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• 제13권1호
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• pp.39-52
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• 2002

The present experiments were designed to study the influence of Baekgumhwan on immune function of ICR mice under stress condition. Baekgumhwan was orally administered to the mice for 15days. on the 11th day the mice subjected to electric footshock for 5days(2 session a day, 11 footshocks a 31 min-session). B/T cell populations in splenocytes were studied by FACS analysis and cytokines($IFN-{\gamma}$ rand IL-10) production of the mouse splenocytes treated with PHA were studied by sandwich ELISA assay on the 15th day. The results were as follows. 1. After electric footshock, mice became sluggish and crowded to one side of the cage. Increased B/T cell populations in splenocytes were observed. These results confirm that electric footshock caused stress inducing immunological and behavioral changes in ICR mice. 2. Baekgumhwan administration without stress increase B cell populations in splenocytes, but T cell populations and cytokines($IFN-{\gamma}$ and IL-10) production of the mouse splenocytes treated with PHA maintain as similar levels as in the normal group. 3. Baekgumhwan administration with stress significantly antagonized the effect of electric footshock on behavior, increased B cell populations in splenocytes, so maintain as similar levels as in the normal group. cytokines($IFN-{\gamma}$ rand IL-10) production of the mouse splenocytes treated with PHA maintain as similar levels as in the normal group and T cell populations in splenocytes were increased as stress control.

• 동의신경정신과학회지
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• 제4권1호
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• pp.99-119
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• 1993

In order to compare and examine the effect the effect of Kuibitang, Kamiondarmtang and Kuibiondarmtang against stress, I induced immobilization stress by binding rats for 200mins under a little anesthetized with ether. I classified as normal group, control group which administrated 0.9% NaCl solution, sample A group which administrated Kuibitang, sample B group which administrated Kamiondarmtang and sample C group which administrated Kuibiondarmtang. I got some conclusions by measuring amounts of norepinephrine, epinephrine, triiodothyronine($T_3$) and thyroxine($T_4$) in 1, 3 and 5 days, respectively. 1. Norepinephrine showed high meaningful decrease after 1. 3 and 5 days in sample A group. It showed little decrease in sample B group. It showed a little meaningful decrease after 1 day and high meaningful decrease after 3 and 5 days in sample C group. 2. Epinephrine showed high meaningful decrease after 3 and 5 days in sample A group. It showed little decrease in sample B group. It showed a little meaningful decrease after 3 days and high meaningful decrese after 5 days in sample C group. 3. Triiodothyronine($T_3$) inclined to approach normal value in sample A, B, C group in comparision wit control group but didn't have high meaning. 4. Thyroxine($T_4$) inclined to approach normal va1ue in sample A, B, C group in comparision with contrl group but didn't have high meaning. As I consider the effect of experiments, I think that Kuibitang and Kuibiondarmtang have some effects against stress and it is right to apply to the treatment of stress.

• 동의신경정신과학회지
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• 제21권2호
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• pp.61-73
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• 2010

Objectives : The purpose of this study was to assess anti-depressive effects of Bee Venom(BV) on an Animal Model of Depression induced immobility stress. Methods : There was 2 pre-experiments MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and Western blot test and 3 main experiments ; forced swimming test, tail suspension test and Y-maze task. Male rats were used for main experiment. The subject was divided into 4 groups(1. control group injected only saline, without immobility stress 2. Negative group injected saline after 2 hours immobility stress 3. Positive group injected Amitriptyline after 2 hours immobility stress 4. BV group injected Bee Venom after 2 hours immobility stress). Each group consisted of 6 rats. Forced swimming test, tail suspension test, Y-maze task were used to evaluate anti-depressive effect of Bee Venom. Results : In MTT assay, as the density of BV increased, the existence rate of primary neuronal cell increased. In Western blot test, the density of CREB and AKT was increasing as time went by. In forced swimming test, BV group showed immobility decreased more than Normal group and Positive group. In tail suspension test, Normal group and Positive group showed immobility decreased more than BV group. In Y-maze task, BV group showed immobility decreased more than Normal group, but Positive group showed immobility decreased more than BV group. Conclusions : These results suggest that Bee Venom may have anti-depressive effect on depression.

• 생약학회지
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• 제37권1호통권144호
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• pp.16-20
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• 2006

The protective effects of the aqueous MeOH extracts of stem and root Acanthopanax koreanum Nakai against oxidative stress were investigated. Anti-oxidant activity of the stem extract of A. koreanum was observed in the DPPH free radical scavenging $(IC_{50}=58.7\;{\mu}g/ml)$ and the SOD test $(IC_{50}=17.52\;{\mu}g/ml)$. According to data analysis of cell survival ratio of normal fibroblasts, the skin irritation by both extracts from A. koreanum was concerned. However, in the skin primary parch test, both extracts obtained Grade I, which means that there was no skin irritation. After induction of oxidative irritation, cell survival ratio of normal fibroblasts was also monitored and it turned out that stress-inducing group with both extracts had more increased cell survival ratio. The cell extension of the stress-inducing group treated with the stem extract was most dominant in morphological study. Based on these results, the stem extract of A. koreanum showed the protective effect against oxidative stress on normal fibroblast.

• 정신신체의학
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• 제6권1호
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• pp.3-12
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• 1998

Objective : The sensation of dysphagia, heartburn, globus hystericus, and functional dyspepsia are common symptoms of the functional upper gut disorders. This study was designed to investigate quantity of perceived stress, depression, and anxiety in the patients with functional upper gut symptoms whose esopahgeal manometry(EM) and gatroesophageal reflux (GERT) test were normal. Methods : A total of 38 patients who complained of the symptoms had been tested with 24-hour ambulatory EM and conventional GERT in our gastrointestinal clinic. Thirty patients whose tests had been normal(patients group) were assessed with Symptom Checklist-90-Revision(SCL-90-R), Beck Depression Inventory(BDI), and Spielberger Stait-Trait Anxiety Inventory(STAI) and compared with 30 patients(control group) without functional upper gut symtpoms in the hepatobiliary clinic. The two groups were also assessed by quantity of perceived stress during the last year through self-report. Results: 1) These patients tended to be predominently female, older, and possessed a lower education than control group. 79% of 38 patients who had been tested were normal. 2) Compared to the control group, the patients had significantly higher mean scores on four subscales(somatization, depression, anxiety, and positive symptom distress index). 3) The patient group had significantly more perceived stress than the control group. 4) The patients group had significantly higher levels of depression than the control gorup, but there was not any significant difference in the STAI. 5) There were significant positive correlations between the BDI score and the STAI-trait, the STAI-stait and the STAI-trait, the quantity of perceived stress and the STAI-trait. Conlusion : The patients with functional upper gut symptoms displayed more, psychological distress, sornatization, anxiety, and deperssion. Among them, patients had higer depression than control group. Functional upper gut symtoms could be more appropriately viewed as somatic symptoms of depression. These findings suggest that such patients need to have psychiatric intervention and treatment.

• Steel and Composite Structures
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• 제33권4호
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• pp.489-507
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• 2019

In order to obtain high bearing capacity and good ductility simultaneously, a structural column with hybrid normal and high strength steel (HNHSS) welded box section has been developed. Residual stress is an important factor that can influence the behaviour of a structural member in steel structures. Accordingly, the magnitudes and distributions of residual stresses in HNHSS welded box sections were investigated experimentally using the sectioning method. In this study, the following four box sections were tested: one normal strength steel (NSS) section, one high strength steel (HSS) section, and two HNHSS sections. Based on the experimental data from previous studies and the test results of this study, the effects of the width-to-thickness ratio of plate, yield strength of plate, and the plate thickness of the residual stresses of welded box sections were investigated in detail. A unified residual stress model for NSS, HSS and HNHSS welded box sections was proposed, and the corresponding simplified prediction equations for the maximum tensile residual stress ratio (${\sigma}_{rt}/f_y$) and average compressive residual stress ratio (${\sigma}_{rc}/f_y$) in the model were quantitatively established. The predicted magnitudes and distributions of residual stresses for four tested sections in this study by using the proposed residual stress model were compared with the experimental results, and the feasibility of this proposed model was shown to be in good agreement.

• Geomechanics and Engineering
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• 제36권2호
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• pp.145-156
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• 2024

The mechanical properties of the concrete-frozen soil interface play a significant role in the stability and service performance of construction projects in cold regions. Current research mainly focuses on the precast concrete-frozen soil interface, with limited consideration for the more realistic cast-in-place concrete-frozen soil interface. The two construction methods result in completely different contact surface morphologies and exhibit significant differences in mechanical properties. Therefore, this study selects silty clay as the research object and conducts direct shear tests on the concrete-frozen soil interface under conditions of initial water content ranging from 12% to 24%, normal stress from 50 kPa to 300 kPa, and freezing temperature of -3℃. The results indicate that (1) both interface shear stress-displacement curves can be divided into three stages: rapid growth of shear stress, softening of shear stress after peak, and residual stability; (2) the peak strength of both interfaces increases initially and then decreases with an increase in water content, while residual strength is relatively less affected by water content; (3) peak strength and residual strength are linearly positively correlated with normal stress, and the strength of ice bonding is less affected by normal stress; (4) the mechanical properties of the cast-in-place concrete-frozen soil interface are significantly better than those of the precast concrete-frozen soil interface. However, when the water content is high, the former's mechanical performance deteriorates much more than the latter, leading to severe strength loss. Therefore, in practical engineering, cast-in-place concrete construction is preferred in cases of higher negative temperatures and lower water content, while precast concrete construction is considered in cases of lower negative temperatures and higher water content. This study provides reference for the construction of frozen soil-structure interface in cold regions and basic data support for improving the stability and service performance of cold region engineering.