• Journal of Nutrition and Health
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• 제46권2호
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• pp.126-136
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• 2013

This study was conducted in order to investigate the association between hypertension and oxidative stress-related parameters and to evaluate these parameters in subclinical hypertensive patients and normotensive subjects living in Korea. We attempted to determine whether oxidative stress-related parameters would differ between two groups of 227 newly-diagnosed, untreated (systolic blood pressure (BP) ${\geq}$ 130 mmHg and diastolic BP ${\geq}$ 85 mmHg) and 130 normotensive subjects (systolic BP < 120 mmHg and diastolic BP < 80 mmHg). General characteristics of the subjects were collected using a simple questionnaire. From subjects' blood, degree of DNA damage in lymphocytes, the activities of erythrocyte superoxide dismutase, catalase, and glutathione peroxidase, level of plasma total radical-trapping antioxidant potential (TRAP), glutathione, and anti-oxidative vitamins, as well as plasma lipid profiles and conjugated diene (CD) were analyzed. Evaluation of the associations of oxidative stress-related parameters with blood pressure of the subjects was performed using Pearson partial correlation and multivariate logistic regression analysis after adjusting for confounding factors. Several oxidative stress-related parameters were higher in subclinical hypertensive patients than in normotensive subjects. Plasma levels of ${\alpha}$-tocopherol, ${\beta}$-carotene, TRAP, and activity of GSH-px were significantly lower in subclinical hypertensive patients than in normotensive subjects. Increased levels of DNA damage, lipid peroxidation, triglyceride, total cholesterol, and LDL-cholesterol were observed in subclinical hypertensive patients. These results confirm an association between blood pressure and oxidative stress-related parameters and suggest that the pathogenic role of oxidative stress in hypertension might be significant.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권8호
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• pp.420-426
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• 2003

This paper deals with the effect of exciter parameters on the torsional stress of turbine-generator. The excitation system effects on the AC network stability and the turbine-generator stress. However. it, until now, have not reported that any parameter among exciter parameters is related to the stability and the stress. In order to verify those CIGRE HVDC model was used. Since the AC network with HVDC has the voltage stability problem due to big capacitor, the worst condition to analyze the stress can considered. The EMTDC program is used for the simulation studies.

• Elastomers and Composites
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• 제47권3호
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• pp.223-230
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• 2012

응력완화 실험 곡선을 Eyring-Halsey 비뉴톤 모델의 이론식에 적용하여 poly(methyl acrylate)-poly(acrylonitrile) 공중합체의 유변학적 파라메타를 얻었다. 응력완화 실험은 용매기를 부착한 인장 시험기를 사용하였다. 유동 파라메타를 컴퓨터 프로그램을 이용하여 계산하였다. 이들 시료의 유동 파라메타는 유동 단위의 자체확산, 유동점성, 유동 활성화 에너지와 직접적인 연관을 갖는 것으로 규명되었다.

• Elastomers and Composites
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• 제46권3호
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• pp.245-250
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• 2011

Poly(acrylonitrile)-poly(vinyl chloride) 공중합체 섬유의 비결정성 영역에서의 자체 확산 계수와 홀 부피를 응력완화 실험으로 규명하였다. 응력완화 실험은 용매기를 부착한 인장 시험기를 사용하였다. 이론적인 응력완화식 에 응력완화 실험 결과를 적용하여 여러 가지 유동 파라메타를 계산하였다. 유동 파라메타로부터 섬유고분자 물질의 홀부피, 자체확산, 점성, 열역학파라메타 등을 계산하였다. 이들 시료의 유동 파라메타는 유동 단위의 홀 부피, 자체확 산, 유동 활성화 에너지와 직접적인 연관을 갖는 것으로 규명되었다.

• Geomechanics and Engineering
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• 제37권3호
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• pp.213-222
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• 2024

Determination of jointed rock mass properties plays a significant role in the design and construction of underground structures such as tunneling and mining. Rock mass classification systems such as Rock Mass Rating (RMR), Rock Mass Index (RMi), Rock Mass Quality (Q), and deformation modulus (Em) are determined from the jointed rock masses. However, parameters of jointed rock masses can be affected by the tunnel depth below the surface due to the effect of the in situ stresses. In addition, the geomechanical properties of rocks change due to the effect of metamorphism. Therefore, the main objective of this study is to apply correlation analysis to investigate the relationships between rock mass properties and some parameters related to the depth of the tunnel studied. For this purpose, the field work consisted of determining rock mass parameters in a tunnel alignment (~7.1 km) at varying depths from 21 m to 431 m below ground surface. At the same excavation depths, thirty-seven rock types were also sampled and tested in the laboratory. Correlations were made between vertical stress and depth, horizontal/vertical stress ratio (k) and depth, k and Em, k and RMi, k and point load index (PLI), k and Brazilian tensile strength (BTS), Em and uniaxial compressive strength (UCS), UCS and PLI, UCS and BTS. Relationships were significant (significance level=0.000) at the confidence interval of 95% (r = 0.77-0.88) between the data pairs for the rocks taken from depths greater than 166 m where the ratio of horizontal to vertical stress is between 0.6 and 1.2. The in-situ stress parameters affected rock mass properties as well as metamorphism which affected the geomechanical properties of rock materials by affecting the behavior of minerals and textures within rocks. This study revealed that in-situ stress parameters and metamorphism should be reviewed when tunnel studies are carried out.

• 여성건강간호학회지
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• 제28권3호
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• pp.187-196
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• 2022

Purpose: The purpose of this study was to investigate factors related to the levels of health-related quality of life (HRQoL) in elderly women based on Wilson and Cleary's HRQoL model. Methods: This study analyzed data from the eighth Korea National Health and Nutrition Examination Survey 2019 on 868 women over the age of 65 years. Based on the HRQoL model, parameters were categorized as personal, environmental, and physiological characteristics; symptom status; functional status; and perception of health status. The data were analyzed by quantile regression. Results: The overall level of HRQoL was 0.87. Factors related to HRQoL in the 10% quantile were higher education level, higher economic status, economic activity, more walking days, fewer diseases, lower stress, less activity limitation, and higher perceived health status. Factors related to the 25% quantile of HRQoL were more walking days, fewer diseases, less activity limitation, and higher perceived health status. Factors related to the 50% quantile were age, economic activity, more walking days, fewer disease, lower stress, less activity limitation, and higher perceived health status. Factors related to the 75% quantile of HRQoL were smoking, more walking days, fewer diseases, lower stress, less activity limitation, and higher perceived health status. Conclusion: While differing parameters were identified according to the level of HRQoL of elderly women in Korea, there were five common factors. Interventions that focus on increasing walking, mitigating diseases, stress, and activity limitations, and improving perceived health status can improve HRQoL.

• 한국압력기기공학회 논문집
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• 제18권2호
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• pp.61-68
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• 2022

Accurate evaluation of residual stress is important for stress corrosion cracking assessment. In this paper, electron beam welding experiment is simulated via finite element analysis and the sensitivity of the parameters related to the combined heat source model is investigated. Predicted residual stresses arecompared with measured residual stresses. It is found that the welding efficiency affects the size of the tensile residual stress area and the magnitude of maximum longitudinal residual stress. It is also found that the parameter related to the ratio of energy distributed to the two-dimensional heat source has little effect on the size of tthe tensile residual stress area, but affects the size of the longitudinal residual stress in the center of the weld.

• 대한화학회지
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• 제58권3호
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• pp.251-257
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• 2014

Poly(methyl acrylate)-poly(acrylonitrile) 공중합체의 응력완화 실험은 용매기를 부착한 인장 시험기를 사용하여 여러 온도의 공기 중, 증류수 용액에서 실행하였다. Eyring-Halsey 모델의 이론적인 응력완화식에 응력완화 실험 결과를 적용하여 여러 가지 유동 파라메타를 계산하였다. 비결정성 영역에서의 유동단위의 고찰을 위하여 유동 파라메타와 결정크기로부터 섬유고분자 물질의 자체확산, 홀 부피, 점성, 열역학파라메타 등을 계산하였다. 이들 시료의 유동 파라메타는 유동 단위의 홀부피, 자체확산, 유동 열역학 파라메타와 직접적인 연관을 갖는 것으로 규명되었다.

• 비파괴검사학회지
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• 제27권6호
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• pp.550-555
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• 2007

Stress intensity factor is one of the most important parameters in fracture mechanics. Both the stress field distribution and the crack propagation are closely related to these parameters. Due to the complexity of actual engineering problems, it is difficult to calculate the stress intensity factor by theoretical formulation, so photoelasticity method is a good choice. In this paper, modified two parameter method is employed to calculate stress intensity factor for opening mode by using data from more than one photoelastic fringe loop. For getting accurate experiment results, the initial fringes are doubled and sharpened by digital image programs from the fringe patterns obtained by a CCD camera. Photoelastic results are compared with those obtained by the use of empirical equation and FEM. Good agreement shows that the methods utilized in experiments are considerably reliable. The photoelastic experiment can be used for bench mark in theoretical study and other experiments.

• 정신신체의학
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• 제28권1호
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• pp.81-88
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• 2020

연구목적 이 연구는 심박변이도(Heart rate variability, HRV) 지표를 이용하여, 불안장애, 우울장애, 외상 및 스트레스 관련 장애의 차이를 비교하고 증상 심각도와의 연관성을 보고자 한다. 방 법 2017년부터 2018년까지 국립정신건강센터 스트레스 클리닉 내원 환자의 후향적 의무기록을 분석하였다. 총 473명 환자(불안장애 166명, 우울장애 184명, 외상 및 스트레스 관련 장애 123명)의 HRV 지표의 진단 군간 차이를 비교하였다. 또한 지표와 전반적 임상 인상 심각도(Clinical Global Impression-Severity Scale, CGI-S)의 연관성이 진단군에 따른 차이를 보이는지 분석하였다. 결 과 세 군에서 HRV 지표는 유의한 차이를 보이지 않았다. 그러나, 심박도 간격(normal-to-normal, NN)의 표준 편차(standard deviation of normal RR intervals, SDNN)와 연속된 NN 간격들의 변이의 제곱 평균값의 루트 값(the square root of the mean squared differences of successive NN intervals, RMSSD)의 CGI-S와의 관련성은 그룹 간 유의한 차이가 나타났다(SDNN, p=0.017 ; RMSSD, p=0.034). 불안장애와 우울장애에서는 CGI-S에 따른 SDNN, RMSSD가 음의 관련성을 보였지만, 외상 및 스트레스 관련 장애에서는 양의 관련성을 보였다. 결 론 본 연구에서 세 군의 HRV 지표는 차이를 보이지 않았지만, 각 군에서 지표와 임상적 심각도와의 연관성은 다른 양상을 보였다. 본 연구 결과는 외상 및 스트레스 관련 장애군은 HRV의 특징 및 임상적 활용이 불안 및 우울장애와 다를 수 있음을 시사한다.