• Korea-Australia Rheology Journal
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• 제17권4호
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• pp.149-156
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• 2005

A simple constitutive model for viscoelastic suspensions is discussed in this paper. The model can be used to predict the rheological properties (relative viscosity and all stresses) for viscoelastic suspensions in shear and elongational flow, and the constitutive equations combine a 'viscoelastic' behaviour component and a 'Newtonian' behaviour component. As expected, the model gives a prediction of positive first normal stress difference and negative second normal stress difference; the dimensionless first normal stress difference strongly depends on the shear rate and decreases with the volume fraction of solid phase, but the dimensionless second normal stress difference (in magnitude) is nearly independent of the shear rate and increases with the volume fraction. The relative viscosities and all the stresses have been tested against available experimental measurements.

• 한국생활과학회지
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• 제21권6호
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• pp.1199-1210
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• 2012

This study investigated the influence of obesity on depression and stress by analyzing the results of the national survey on health and nutrition. Relationships between normal, obese, and severely obese groups were investigated. The results of the study are as follows. First, obesity caused by demographic variables showed a relationship to both gender and average monthly income. In the case of the seriously obese group, females had higher rates of depression than males, and the high obesity group had lower average monthly income than the normal and obese groups. Second, obesity caused by health-related variables found that high blood pressure, hyperlipidemia, and diabetes that was not angina-related displayed higher rates of depression in the serious obesity group than in the other groups. As for subjective evaluations of one's own health condition, the serious obesity group showed a high tendency to evaluate their own health conditions negatively. Third, the difference between depression and stress related to obesity level showed no difference between the normal weight group and the obesity group; however, the seriously obese group demonstrated relatively higher occurrences of depression and higher stress scores. Fourth, the result for depression and stress level caused by demographic variables, health-related variables, and obesity demonstrated a direct relationship to gender, subjective level of satisfaction with one's personal finances, average monthly income, subjective perception of one's own health and severely obesity status. More specifically, it was found that the ratio of depression and stress score was higher when the subject was female, among those whose subjective evaluation of their own finances and health condition was negative, and those who suffered from severe obesity.

• 한방재활의학과학회지
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• 제20권4호
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• pp.147-157
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• 2010

Objectives : The study is performed to investigate the influence of psychological stress on neck muscles tone and heart rate variability(HRV). Methods : This study was carried out with the data from stress response index score(SRI), surface electromyography(sEMG) and HRV. First subjects were divided into two group according to the SRI points. Subjects in group A had points of SRI in which lower than 30 points. Subjects in group B had points of SRI in which higher than 30 points. Then we investigated how to difference of the index of sEMG and HRV according to each groups. Results : In this study, the muscle contraction of both upper trapezius muscle in stress group were higher than non-stress group significantly. Complexity, root mean square of successive differences of R-R intervals(RMSSD), standard deviation difference between adjacent normal to normal intervals(SDSD), high frequency oscillation power(Ln(HF)), normalized HF(Norm HF) in stress group were lower than non-stress group significantly and normalized LF(Norm LF) was higher. Conclusions : This results show that the stress was associated with neck muscle condition and autonomic nervous system.

• 원예과학기술지
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• 제33권5호
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• pp.625-632
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• 2015

Drought is a severe abiotic stress that affects global crop production. A drought model was created for 'Toyonoka' Fragaria ${\times}$ ananassa, and the effects of drought stress on contents of proline, sugars, and antioxidant enzyme activities were investigated. Strawberry transplants with identical growth were chosen for the experiments and the randomized design included four replications (10 plants per block). The experimental sets differed in the moisture level of the culture medium relative to the range of moisture content as follows: control, 70-85%; mild drought stress, 50-60%; moderate drought stress, 40-50%; and severe drought stress, 30-40%. Drought stress was imposed by limiting irrigation. Plants were sampled and physiological parameters w ere measured on 0, 2, 4, 6, 8, and 10 days after the commencement of droughts tress. The water potential of strawberry leaves decreased in the plants under mild, moderate, and severe stress during the course of the water stress treatment and exhibited a significant difference from the control. Strawberry leaves subjected to drought stress had higher accumulation of proline, sugars, and malondialdehyde, and higher activities of superoxide dismutase, peroxidase, and catalase than leaves of control plants. Malondialdehyde levels increased in parallel with the severity and duration of drought stress. By contrast, antioxidant enzyme activity displayed dynamic responses to drought stress, first increasing and subsequently decreasing as the severity and duration of drought stress increased. These results suggest that strawberry plants respond to drought stress by altering the activities of antioxidant enzymes and the levels of osmotically active metabolites. These biochemical response changes may confer adaptation to drought stress and improve the capacity of plants to withstand water-deficit conditions.

• 대한한의학회지
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• 제24권3호
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• pp.23-34
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• 2003

Objective : In 2001, the rate of obesity in Korea reached 30.6%. There are many therapeutic ways to reduce body weight, such as low and very low calorie diet, exercise therapy, behavior modification therapy, etc. However, in many cases the patients feel stress under obesity treatment because of starvation. This study was aimed to evaluate the anti-starvation stress effect of Coicis Semen on mice. Methods : First, the mice were divided into 6 groups : Normal (group with no starvation), Control (administrated normal saline 6 times before starting 36 hours starvation), and Samples A, B, C, and D (administrated 0.25, 0.5, 1.0, 3.0 g/kg Coicis Semen respectively 6 times before starting 36 hours starvation). Then the plasma corticosterone level and rectal temperature were measured. The norepinephrine, dopamine, DOPAC (dihydroxy-phenylacetic acid), 5-HT (5-hydroxytryptamine) and 5- HIAA (5-hydroxy-indole-acetic acid) in the hypothalamus were measured by the HPLC method. Result : I. The rectal temperature in Sample group D showed a significant difference (P<0.05) compared with the Control group. 2. The DOPAC in Sample groups A, C and D showed the significant difference (P<0.05) compared with the Control group. Conclusion : It might be recognized that Coicis Semen has an anti-starvation stress effect.

• 대한임상전기생리학회지
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• 제5권2호
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• pp.11-21
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• 2007

The purpose of this study were to investigate influence of heat stress temperature on sympathetic nerve activities. Subjects were 8 normal adults (4 men, 4 women, 21.36 years old). First sympathetic nerve activities were measured at the point that increase of core temperature stops at the state of applying normal thermic temperature (NIT; $34^{\circ}C$). After measurement, temperature of bathtub was increased to heat stress temperature (HST; $46^{\circ}C$) and sympathetic nerve activities were remeasured at the point that temperature increase stops. Sympathetic skin response (SSR) were analyzed using EMG, IR thermometer, and auto stethoscope. SSR latency showed significant differences at both palms by electrical stimulation to median nerve (p<.05). Electrical stimulation to forehead showed significant difference at left palm (p<.05) and electrical stimulation to navel showed significant difference at right palm (p<.05). Median nerve in changes of SSR amplitude showed significant differences at both palms in HST (p<.01). Electrical stimulation to navel showed significant difference at left palm (p<.05). Ts of forehead and xiphoid process showed significant differences (p<0.01). Tc of oral (p<0.05) and inner ear (p<0.01) showed significant differences. Pulse rate showed significant difference (<0.05). This study showed that immersion in HST had significant decrease of excitability in sympathetic nervous system compared to immersion in NTT.

• Korea-Australia Rheology Journal
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• 제13권3호
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• pp.141-148
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• 2001

In this research, experimental studies leave been performed on the hydrodynamic interaction between a spherical particle and a plane wall by measuring the force between the particle and wall. To approach the system as a resistance problem, a servo-driving system was set-up by assembling a microstepping motor, a ball screw and a linear motion guide for the particle motion. Glycerin and dilute solution of polyacrylamide in glycerin were used as Newtonian and non-Newtonian fluids, respectively. The polymer solution behaves like a Boger fluid when the concentration is 1,000 ppm or less. The experimental results were compared with the asymptotic solution of Stokes equation. The result shows that fluid inertia plays all important role in the particle-wall interaction in Newtonian fluid. This implies that the motion of two particles in suspension is not reversible even in Newtonian fluid. In non-Newtonian fluid, normal stress difference and viscoelasticity play important roles as expected. In the dilute solution weak shear thinning and the migration of polymer molecules in the inhomogeneous flow field also affect the physic of the problem.

• 재활치료과학
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• 제8권4호
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• pp.19-31
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• 2019

목적 : 본 연구에서는 자폐스펙트럼 장애(ASD) 영유아의 어머니를 대상으로 양육 스트레스 총점, 부모영역 및 아동영역 수준에 따라 MMPI-2를 통해 어머니가 경험할 수 있는 양육 스트레스 수준에 따른 다양한 심리적 증상의 차이를 검증하였다. 연구방법 : 서울 소재의 종합병원 소아정신과, 재활의학센터, 발달 장애 클리닉 등에서 2010년에서 2015년까지 ASD로 진단을 받은 만 1세에서 5세까지의 영유아 어머니 72명을 대상으로 실시되어 축적된 한국판 부모 양육 스트레스 척도(K-PSI)와 다면적 인성검사 II(MMPI-2) 자료를 최종분석에 사용하였다. 결과 : 양육 스트레스 총점과 부모영역은 MMPI-2의 여러 임상 척도들과 유의한 상관관계를 나타냈지만, 아동영역은 유의한 상관관계를 나타내지 않았다. 또한, 양육 스트레스 총점 수준에 따른 심리적 증상의 차이를 검증한 결과, 위험 수준 집단이 정상 범위 집단보다 MMPI-2의 임상 척도 중 건강염려증(Hs), 우울(D), 편집증(Pa), 강박증(Pt), 조현병(Sc)이 유의하게 높았다. 양육 스트레스 부모영역에서는 위험 수준 집단이 정상 범위 집단보다 MMPI-2의 임상 척도 중 건강염려증(Hs), 우울(D), 히스테리(Hy), 반사회성(Pd), 편집증(Pa), 강박증(Pt), 조현병(Sc), 경조증(Ma), 내향성(Si)이 유의하게 높았다. 반면에 양육 스트레스 아동영역에서 위험 수준 집단과 정상 범위 집단 간의 차이는 유의하지 않았다. 결론 : 양육 스트레스 총점과 부모영역에서 위험 수준 집단의 심리적 증상이 유의하게 높았다는 것을 확인하였다.

• 한국보육지원학회지
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• 제12권6호
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• pp.19-39
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• 2016

The present study examined differences in children's behavior problems and peer interaction, and parental factors including self-esteem, depression and childrearing stress between atopic dermatitis(AD) and normal(non-AD) children in each gender, and analyzed the effects of the parental factors on the two variables of AD children. 165 AD and 1176 non-AD children of age 5 were selected from the 6th year data of the Panel Study on Korean Children. The results from t-test and multiple regression are as follows. First, only AD boys showed a higher level of behavior problems than non-AD boys, but peer interaction showed no difference between AD and non-AD groups. Compared with non-AD children's parents, mothers of AD children showed a higher stress level and mothers of AD boys had a higher depression level. But there were no differences in maternal self-esteem and paternal factors between the groups. Second, AD boys' behavior problems were related to maternal factors and paternal stress, and some characteristics of AD girls' behavior problems were related with some parental variables. But peer interaction of AD children had no relation with parental factors. Third, behavior problems were influenced by maternal stress in AD boys and influenced by maternal depression and parental self-esteem in AD girls.

• 대한치과보철학회지
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• 제45권5호
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• pp.567-578
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• 2007

Statement of problem: The endodontically treated tooth is generally restored with post and core, owing to the brittle and the loss of large amount of tooth structure. As periodontal treatment was developed, there are many cases that periodontally involved teeth used in prosthetic treatment. Purpose: The purpose of this study was to analyze the stress distribution in the dentin and post structures by the various post materials and the amount of remaining alveolar bone height. Material and method: The 3-dimensional finite element models of mandible 1st premolars were divided into six types according to the various amount of remaining alveolar bone and post type. All types were modeled using equal length, diameter and shape of the post. Three types of post and core materials were used: prefabricated titaniumpost and amalgam core, prefabricated stainless steel post and amalgam core, and cast gold post and core. 300 Newton force was applied to functional cusp of mandible 1st premolar. Results: The results were as follows: First, there was no apparent difference in the pattern of stress distribution according to the alveolar bone condition concentrate on the post middle area. Second, there was difference in pattern of stress distribution according to the core materials, gold post and core generated same than amalgam core. Third, there was no apparent difference in the pattern of stress distribution within the dentin according to the post and core materials. But a cast gold post and core generated the lowest maximum stress value, a stainless steel post generated the highest maximum stress value. Fourth, in the reduced alveolar bone model, maximum stress value is 1.5 times than that of the normal alveolar bone model. Conclusion: Within the limitations of this study, to provide minimal stress to the root with alveolar bone reduced, the post length may be as long as apical seal was not destroyed. To prevent fracture of tooth, it is rational to use gold alloy which material was good for stress distribution for post materials.