• The Journal of Korean Physical Therapy
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• v.4 no.1
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• pp.69-78
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• 1992

The purpose of this survey is to grasp the special school therapeutic education teachers, stress degrees in the real educational fields, and to campare the different stress degrees by the teaching responsibilities, by set by age, by the careers of special teaching profession, by his or her assiduity by the academic careers and teacher qualification, and by the reasons of stress. To perform this survey, the writer analyzed the answer sheets of the questionnairs returned by 85 special school therapeutic education teachers all over the country. The results of the analysis are as follows: First, the mean value of stress by the whole teachers was shown as endurable, and there was no difference among stress towels by the teaching responsibilities. As for the ratio of teachers confronted with the dangerous level of stress. the teachers taking charge of feebleminded school teachers the highest ratio, and those charging of deaf & dumb school teachers, the lowest. Second, the comparison by age didn't result in any difference, but in the relation of age to the handicap division there appeared meaningful differences. That is in the case of the therapeutic education theachers charging of crippled school, it revealed that the older they were, the more stress they suffered. In the case of the teachers charging of visually deaf & dumb school the tendency was opposite. The comparison by the special teaching profession careers, there showed no difference in the stress degree. The high or low academic careers didn't make any influence on the therapeutic education teachers stress degree. Third, The revealed on the highest stress degress, because reasons of relation the student's parents with students behavior.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3369-3376
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• 1994

A finite element program for elastic stress wave propagation is developed in order to investigate the shape of stress field and analysis the magnitude of stress wave intensity at time increment. Accuracy and reliance of the finite element analysis are acquired when the element size is smaller than the product of the stress wave speed and the critical value of increasing time step. In the finite element analysis and theoretical solution, the longitudinal stress wave is propagated to the similar direction of impact load, and the stress wave intensity is expressed in terms of the ratio of propagated area. The direction of shear wave is declined at an angle of 45 degrees compared with longitudinal stress wave and the speed of shear wave is half of the longitudinal stress wave.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.2
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• pp.86-95
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• 2003

During this study, constant stress ratio tests with previous compression anisotropic stress history are performed on compacted decomposed granite soil sampled at Iksan, Jeonbuk. Yielding points are determined from stress-strain curves. The shape and characteristics of compression anisotropic yield curves is examined. In addition, the measured value of yielding curve and stress-strain behavior is predicted by Yasufuku's anisotropic constitutive model based on non-associated flow rule. The main results are summarized as follows : 1) Shape of yielding curves shows almost ellipse but asymmetry with respect to stress path during previous consolidation stress. 2) Yasufuku's anisotropic constitutive model is suitable in evaluation of yielding curves on anisotropic consolidated decomposed granite soil. 3) The predicted stress-strain curve shows reasonable agreement to measured behaviours.

• Journal of the Korean GEO-environmental Society
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• v.15 no.1
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• pp.25-34
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• 2014

The aim of this study is to analyze the mechanical characteristics and settlement feature of the composite ground with structural form changes. The laboratory model test is a soil tanker to be contained with clay and grid form improved soil, which is conducted in total 9 case with the uniaxial compressive strength of improved soil and replacement ratio of improved soil. The numerical analysis for variation of stress distribution ratio with depth was performed in the same conditions which are the laboratory model test. As a result, stress distribution ratios in mid and high replacement ratio are increasing and settlement is decreasing, except low replacement ratio. This study is presented for form effect ratio and settlement reduction factor with change of structure form, which is able to be helpful in further research and reference for change of structural forms at composite ground.

• The Journal of the Korean dental association
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• v.54 no.11
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• pp.897-906
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• 2016

Objectives: Periodontitis is multifactorial disease mainly caused by microbial community. Recently, some research has been conducted to find other possible risk factors including stress hormones related to periodontitis. Psychological stress can affect the periodontal health by a variety of biological mechanisms. This study compared the stress hormone levels in healthy subjects and patients with periodontal disease using saliva in order to investigate the association between periodontitis and stress. Methods: The human saliva was collected from 38 periodontally healthy individuals and 34 patients with chronic periodontitis under Institutional Review Board. Their age was 20-60 years ($40.3{\pm}10.45$). From these samples, determination of salivary levels of cortisol and Dehydroepiandrosterone (DHEA) performed by enzyme immunoassay kit (Salimetrics Europe, Suffolk, UK). The independent t-test and Mann-Whitney test for trend was applied using IBM SPSS statistics version 12.0 Program to analyze statistically significant differences. Results: Salivary cortisol levels of periodontitis patients were higher than those levels of healthy subjects (P < 0.001), while salivary DHEA levels of periodontitis patients were not significantly different (P = 0.431). Salivary cortisol/DHEA ratio of periodontitis patients was higher than those levels of healthy subjects (P < 0.001). Conclusions: Our study demonstrates the high levels of cortisol concentrations and cortisol/DHEA ratio in saliva of periodontitis patients than those of healthy subjects. Since cortisol levels and cortisol/DHEA ratio can be significant factors related to the severity of periodontal disease, our study would be helpful for early diagnosis and treatment of periodontal disease.

• Korean Journal of Pharmacognosy
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• v.37 no.1 s.144
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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.

• Journal of Life Science
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• v.9 no.5
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• pp.537-547
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• 1999

This study was designed to investigate the effects of sea tangle (Laminaria japonica) extract (Dasi-Ex group: dry base 4.0%) and fucoidan-added (Fuco-I, II, III group: fucoidan of 1.0%, 2.0%, 3.0% added to Dasi-Ex) beverages on the anti-stress action. ICR male mice (20$\pm$2g) were fed basic experimental diets and given free through water bottle filled with these beverages instead of water for 18 days including sociopsychological stress. Body weight gains were consistently lower in Dasi-Ex and Fuco-I,II,III groups compared with control group, expecting in a inhibitory effect of obesity. Dasi-Ex group resulted in a significant decrease of 25% in serum corticosterone (CS) secretion, while Fuco-I,IIand IIIgroups resulted in a marked decreases of 45~55% in serum CS secretion compared with control group. Noradrenaline (NA) secretions were significantly increased about 15% in Dasi-Ex group, and 20~22% in Fuco-I,II,III groups compared with control group. Significant differences in brain MHPG-SO4 levels of Dasi-Ex group could not be obtained, but Fuco-I,II,III groups resulted in a marked decreases of 20~25% in brain MHPG-SO4 ratio of brain, but Fuco-I,II and III groups resulted in a marked increases of 45~60% in NA/MHPG-SO4 ratio of brain compared with control group. These results suggest that fucoidan beverage may play a effective role in a ridding of the sociopsychological stress by pivotal anti-stress effect of fucoidan.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.18 no.3
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• pp.66-74
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• 2005

Objective: Stress is one of the most important etiological factors in our lives. Human body makes effort to keep his homeostasis from stress by using autonomic nerve system. So we need markers which can evaluate autonomic nerve system easily. HRV represents such markers. Sympathetic and Parasympathetic nerve system are part of autonomic nerve system, related with cur body and diseases in ENT, Dermatology, Ophthalmology are also deeply related with stress, Sympathetic and Parasympathetic nerve system. So we can expect that it can help understanding patients to evaluate autonomic nerve system with HRV Research Methods and Procedures: Forty one patients who have seif-recognized stress in Dept. of Oph & Otolaryngo & Dermatology were selected. SDNN. RMSSD, LF, HF, norm-LF, norm-HF, LF/HF ratio, LnLF, LnHF were checked. Results: Men showed lower SDNN, HF, and LnHF than women(p<0.05). Age over-forty group showed significant lower SDNN, LF, HF, LnLF, LnH(p<0.01), and lower RMSSD(p<0.05) than age under-forty group. There's no big differences for age at norm-LF, norm-HF, and LF/HF ratio. Skin disease group showed higher SDNN, RMSSD, LF, HF, LnLF, LNHF than the others, facial palsy group showed higher norm-HF. LF/HF ratio, and mouth-throat group showed higher norm-LF, but there's no statically significant difference. Comparing skin disease group with the others, the others showed statically significant low SDNN(P<0.01), RMSSD, LF, HF, LnLF and LnHF(P<0.05).

• Steel and Composite Structures
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• v.33 no.4
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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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• v.6 no.2
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• pp.173-194
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• 2014

Laboratory and field data showed that deep mixed (DM) columns accelerated the rate of consolidation of the soft foundations. Most analyses of consolidation of DM column-improved foundations so far have been based on the elastic theory. In reality, the DM columns may yield due to the stress concentration from the soft soil and its limited strength. The influence of column yielding on the degree of consolidation of the soft foundation improved by DM columns has not been well investigated. A three-dimensional mechanically and hydraulically-coupled numerical method was adopted in this study to investigate the degree of consolidation of the DM column foundation considering column yielding. A unit cell model was used, in which the soil was modeled as a linearly elastic material. For a comparison purpose, the DM column was modeled as an elastic or elastic-plastic material. This study examined the aspects of stress transfer, settlement, and degree of consolidation of the foundations without or with the consideration of the yielding of the DM column. A parametric study was conducted to investigate the influence of the column yielding on the stress concentration ratio, settlement, and average degree of consolidation of the DM column foundation. The stress concentration ratio increased and then decreased to reach a constant value with the increase of the column modulus and time. A simplified method was proposed to calculate the maximum stress concentration ratios under undrained and drained conditions considering the column yielding. The simplified method based on a composite foundation concept could conservatively estimate the consolidation settlement. An increase of the column modulus, area replacement ratio, and/or column permeability increased the rate of consolidation.