• Smart Structures and Systems
• /
• v.7 no.4
• /
• pp.275-287
• /
• 2011

The behaviors of saturated soils such as compressibility and permeability are distinguished by preconsolidation stress. Preconsolidation stress becomes an important design parameter in geotechnical structures. The goal of this study is to introduce a new method for the evaluation of preconsolidation stress based on the shear wave velocity at small strain, using Busan, Incheon, and Gwangyang clays in Korea. Standard consolidation tests are conducted by using an oedometer cell equipped with bender elements. The preconsolidation stresses estimated by shear wave velocity are compared with those evaluated by the Casagrande, constrained modulus, work, and logarithmic methods. The preconsolidation stresses estimated by the shear wave velocity produce very similar values to those evaluated by the Onitsuka method (one of the logarithmic methods), which yields an almost real preconsolidation stress. This study shows that the shear wave velocity method provides a reliable method for evaluating preconsolidation stress and can be used as a complementary method.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.8
• /
• pp.830-837
• /
• 2011

A genomic DNA fragment encoding a putative maltooligosyltrehalose trehalohydrolase (NfMTH) for trehalose biosynthesis was cloned by the degenerate primer- PCR from cyanobacterium Nostoc flagelliforme. The ORF of NfMTH is 1,848 bp in length and encodes 615 amino acid residues, constituting a 70 kDa protein. The deduced amino acid sequence of NfMTH contains 4 regions highly conserved for MTHs. By expression of NfMTH in E. coli, the function of this protein was demonstrated, where the recombinant protein catalyzed the hydrolysis of maltooligosyl trehalose to trehalose. The expressions of MTH and maltooligosyltrehalose synthase in the filaments of N. flagelliforme were upregulated significantly under dehydration stress, NaCl stress, and high temperature-drought stress. The accumulations of both trehalose and sucrose in the filaments of N. flagelliforme were also improved significantly under the above stresses. Furthermore, trehalose accumulated in smaller quantities than sucrose did when under NaCl stress, but accumulated in higher quantities than sucrose did when under temperature-drought stress, indicating that both trehalose and sucrose were involved in N. flagelliforme adapted to stresses and different strategies conducted in response to various stress conditions.

• Journal of Korean Clinical Nursing Research
• /
• v.14 no.2
• /
• pp.127-138
• /
• 2008

Purpose: To examine the effects of the environmental nursing intervention using eye-shields and earplugs on the incidence of delirium, environmental stress and sleep among the patients with open-heart surgery in the post-cardiac ICU(intensive care units). Method: This study was a non-equivalent control group non-synchronized design. The subjects consisted of 93 patients who received ICU care after the cardiac surgery. Among those, 32 subjects was assigned in one experimental group with eye-shields, 31 in the other experimental group with earplugs, and 30 in the control group. ICU delirium was measured by CAM-ICU, environmental stress by ICUESS, and sleep by two sleep scales developed by Oh, et al. and Kim. The data were analyzed by the SPSS 13.0 program including frequency, percentage, t-test, $x^2$ test, ANOVA and ANCOVA. Results: There are no statistically significant differences in the incidence of delirium among three groups (p=.139). The ICU environmental stress scores from the subjects of two experimental groups demonstrated lower (F=6.731, p=.002) than the control group. Also, the degrees of sleep pattern (p=.000, p=.000) and sleep satisfaction (p=.000, p=.000) were greater than those of the control group. Conclusion: Although the environmental nursing intervention using eye-shields and earplugs did not demonstrate the effects in decreasing the incidence of ICU delirium, it has affirmative effects in decreasing environmental stress and improving the quality sleep among the patients with open-heart surgery while they stay in ICU. Further nursing implications are discussed.

• Journal of Ecology and Environment
• /
• v.29 no.5
• /
• pp.479-484
• /
• 2006

Ecophysiological parameters of non-transgenic sweetpotato (NT) and transgenic sweetpotato (SSA) plants were compared to evaluate their resistance to multiple environmental stresses. Stomatal conductance and transpiration rate in NT plants decreased markedly from Day 6 after water was withheld, whereas those values in SSA plants showed relatively higher level during this period. Osmotic potential in SSA plants was reduced more negatively as leaf water potential decreased from Day 8 after dehydration treatment, while such reduction was not shown in NT plants under water stressed condition. SSA plants showed less membrane damage than in NT plants. As water stress and high light stress, were synchronously applied to NT and SSA plants maximal photochemical efficiency of PS II ($F_v/F_m$) in NT plants markedly decreased, while that in SSA plants was maintained relatively higher level. This trend of changes in $F_v/F_m$ between SSA plants and NT plants was more conspicuous as simultaneously treated with water stress, high light and high temperature stress. These results indicate that SSA plants are more resistive than NT plants to multiple environmental stresses and the enhanced resistive characteristics in SSA plants are based on osmotic adjustment under water stress condition and tolerance of membrane.

• Korean Journal of Soil Science and Fertilizer
• /
• v.47 no.3
• /
• pp.213-216
• /
• 2014

Arsenic is a known hazardous metalloid not only to the animals but also to plants. With high concentrations, it can impede normal plant growth and cause even death of plants at extremely high levels. A known plant response to stress conditions such as toxic levels of metal (loids) is the production of stress ethylene, causing inhibitory effect on root growth in plants. When the effect of various arsenic concentrations was tested to maize plant, the stress ethylene emission proportionately increased with increasing concentration of As(V). The inoculation of two arsenic tolerant bacteria; Pseudomonas grimonti JS126 and Pseudomonas taiwanensis JS238 having respective high and low 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity reduced stress ethylene emission by 59% and 30% in maize grown in arsenic polluted soils. The result suggested the possible use of Pseudomonas grimonti JS126 for phytoremediation of arsenic polluted soils.

• Proceedings of the Korean Society of Toxicology Conference
• /
• 2005.05a
• /
• pp.134-134
• /
• 2005

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.966-973
• /
• 2005

The stress concentration ratio in accordance with area replacement ratios were considered as core elements of design. However, the stress concentration ratio will be vary depends on progress of consolidation in clay ground. And, since it is not sure to know the affecting factors accurately, the value is decided based on field experiences. To use SCP method more effective and correspond to soil improvement, the decision on proper area replacement ratio through the exact stress concentration ratio is very important. Accordingly, a numerical analysis on influence of various factors that needed to make rational designing guide for decision of proper area replacement ratio to stress concentration ratio was executed in this study.

• Structural Engineering and Mechanics
• /
• v.76 no.2
• /
• pp.153-162
• /
• 2020

Aiming at the mechanical and structural characteristics of the contact zone composite rock, the shear tests and numerical studies were carried out. The effects of the differences in mechanical properties of different materials and the normal stress on shear properties of contact zone composite samples were analyzed from a macro-meso level. The results show that the composite samples have high shear strength, and the interface of different materials has strong adhesion. The differences in mechanical properties of materials weakens the shear strength and increase the shear brittleness of the sample, while normal stress will inhibit these effect. Under low/high normal stress, the sample show two failure modes, at the meso-damage level: elastic-shearing-frictional sliding and elastic-extrusion wear. This is mainly controlled by the contact and friction state of the material after damage. The secondary failure of undulating structure under normal-shear stress is the nature of extrusion wear, which is positively correlated to the normal stress and the degree of difference in mechanical properties of different materials. The increase of the mechanical difference of the sample will enhance the shear brittleness under lower normal stress and the shear interaction under higher normal stress.

• Fashion & Textile Research Journal
• /
• v.7 no.1
• /
• pp.33-40
• /
• 2005

This study is to develope the job stress model for workers in fashion and textile industries and to investigate the effect of job stressors on stress symptom and its effect on job performance. The structural equation model analysis was performed for examining the relationship among job stressors, stress symptom and job performance. Environmental factors, task factors, role factors and organizational climate factors were identified as job stressors. Task characteristics and role characteristics were positively related to job stress symptom. Environmental factors and organizational climate factors were negatively related to job stress symptom. Also, job stress symptom was negatively related to job performance. The findings suggest some implications on how to improve job performance or to reduce job stress.

• Korean Journal of Occupational Health Nursing
• /
• v.16 no.2
• /
• pp.158-167
• /
• 2007

Propose: To identify the effects of job stress for depression in clinical nurses. Method: The subjects were 304 clinical nurses in Busan Metropolitan City. Data was collected by questionnaire surveys using convenience sampling. The instruments used in this study were the short form of the Korean Occupational Stress Scale(KOSS-SF) and the Beck Depression Inventory-Korean Version Standard Ten(K-BDI STEN). Result: After adjusting potential confounders, we found that the group of 50~75% job stress score for interpersonal conflict was more likely to have depression than the group of less than 25%(OR=3.522, 95% CI 1.06~20.25). The group of equal or more than 75% job stress score for job insecurity was more likely to have depression than the groups of less than 25%(OR=9.413, 95% CI 4.00~71.03). The groups of equal or more than 75% and 50~ 75% job stress score for lack of reward was more likely to have depression than the group of less than 25%, respectively(OR=19.302, 95% CI 2.50~244.25; OR=38.201, 95% CI=6.25~344.45). Conclusion: To prevent depression in clinical nurses, we need to intervene job stress for insufficient job control, interpersonal conflict, job insecurity and lack of reward.