• 한국기계가공학회지
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• 제19권7호
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• pp.81-88
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• 2020

The geometry and the defect of the groove of the part provoke a sudden change of stress in a local region. The objective of this paper is to investigate the effects of the geometry and the imperfection of a small groove on stress distributions in the vicinity of the joined region for the ABS part with a thin wall using a three-dimensional finite element analysis (FEA). Several types of groove are designed to improve joining characteristics in the vicinity joined region. The imperfection model of the small-sized groove is obtained from observation of deposition characteristics of a fused deposition modeling process. Local stress distributions in the vicinity of the joined region are predicted by the FE model with refined meshes. The influence of the angle and the imperfection of the groove on appearance regions of the maximum stress and distributions of the defined principal stress for different loading conditions is examined using the results of FEAs. Finally, a proper design of the groove is proposed to improve joining characteristics between the substrate and the ABS part.

• Structural Engineering and Mechanics
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• 제53권2호
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• pp.205-226
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• 2015

Finite element method (FEM) is an effective quantitative method to solve complex engineering problems. The basic idea of FEM for a complex problem is to be able to find a solution by reducing the problem made simple. If mathematical tools are inadequate to obtain precise result, even approximate result, FEM is the only method that can be used for structural analyses. In FEM, the domain is divided into a large number of simple, small and interconnected sub-regions called finite elements. FEM has been used commonly for linear and nonlinear analyses of different types of structures to give us accurate results of plane stress and plane strain problems in civil engineering area. In this paper, FEM is used to investigate stress analysis of a shear wall which is subjected to concentrated loads and fundamental principles of stress analysis of the shear wall are presented by using matrix displacement method in this paper. This study is consisting of two parts. In the first part, the shear wall is discretized with constant strain triangular finite elements and stiffness matrix and load vector which is attained from external effects are calculated for each of finite elements using matrix displacement method. As to second part of the study, finite element analysis of the shear wall is made by ANSYS software program. Results obtained in the second part are presented with tables and graphics, also results of each part is compared with each other, so the performance of the matrix displacement method is demonstrated. The solutions obtained by using the proposed method show excellent agreements with the results of ANSYS. The results show that this method is effective and preferable for the stress analysis of shell structures. Further studies should be carried out to be able to prove the efficiency of the matrix displacement method on the solution of plane stress problems using different types of structures.

• 대한본초학회지
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• 제31권5호
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• pp.99-106
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• 2016

Objectives : Salvianolic acid B (SAB) is an active ingredient in Salvia miltiorrhiza frequently used for cardiovascular and cerebrovascular diseases. The present study investigated the antioxidant effects of SAB on the skeletal muscle and the brain tissue of rats following exhaustive exercise.Methods : The rats were treated with oral administration of SAB (30 mg/kg) daily for 5 days prior to the exhaustive exercise. The exhaustive exercise was performed as swimming for 150 min with 5% body weight attached to the tail on the 5th day. The antioxidant effects of SAB was evaluated by measuring the superoxide generation in the gastrocnemius and the 4-HNE expression in the hippocampal tissue. In addition, c-Fos-expressing cells in the brain tissue was observed using immunohistochemistry.Results : Histological features and muscle fiber type composition were not different between the SAB group and the exhaustive exercise group. SAB significantly reduced the upregulation of superoxide generation in the muscle tissue. SAB significantly reduced the increase of c-Fos-expressing cells in the cerebral cortex, paraventricular thalamic nucleus, dorsomedial hypothalamic nucleus, the CA1, CA3, and DG regions of hippocampus. SAB significantly reduced the upregulation of 4-HNE expression in the CA1 and DG regions of hippocampus caused by the exhaustive exercise.Conclusions : The results suggest that SAB exerts antioxidative effect against oxidative stress in the skeletal muscle and the brain tissue following exhaustive exercise, while SAB may has an anti-stress effect on stress responses in the brain.

• 디지털융복합연구
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• 제13권8호
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• pp.419-429
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• 2015

본 연구는 고지혈증 유병률의 지역 간 변이 정도와 위험 요인을 규명하여 지역별 특성에 맞는 고지혈증 관리 사업을 지원하기 위한 기초자료를 제공하기 위해 수행되었다. 이를 위해 질병관리본부의 2012년도 시군구 지역사회건강조사 249건의 자료를 이용하여 단순 상관관계 분석, 단계적 회귀분석, 의사결정나무 등의 기법으로 분석하였다. 249개 시군구 지역의 고지혈증 유병률은 9.2%였고, 변동계수는 28.3%였다. 남동부 해안지역에 비해 수도권과 내륙지방의 고지혈증 유병률이 높았다. 의사결정나무 모형이 회귀모형에 비해 예측력이 좋았는데, 지역의 임금근로자 비율, 스트레스 인지율, 고혈압, 협심증, 관절염 유병률이 높은 지역일수록 고지혈증 유병률이 높은 것으로 나타났다. 따라서 사회 역학적 관점에서 지역사회의 개입이 가능한 지점을 중심으로 고지혈증 유병률을 감소시키기 위한 전략 마련이 필요하다.

• Journal of Nutrition and Health
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• 제35권1호
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• pp.24-29
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• 2002

본 연구에서는 녹차 건분 식이가 뇌 조직에서 알코올에 의한 산화적 스트레스 감소효과를 나타내는 지를 규명하고 자, 생후 9개월령 Sprague-Dawley에게 1% 녹차 건분식이를 4주간 공급하고 희생 12시간 전메 급성으로 알코올을 투여한 후 뇌 조직을 cortex, cerebellum, striatum, hippocampus로 나누어 malondialdehyde(MDA)의 함량과 catalase. superoxide dismutase(SOD), glutathione peroxidase(GSH-Px)의 활성을 측정하였다. 본 실험 결과를 종합하여 볼 때. 1%녹차 건분 식이의 공급은 striatum과 hippocampus 내 MDA 함량을 유의적으로 낮추고 알코올에 따른 hippocampus 내 catalase 활성 증가를 유의적으로 억제하였다. 이러한 곁과는 녹차 건분의 공급이 알코올로 산화적 stress를 가한 동물에서 일부 뇌 조직의 지질 산화를 감소시키고 알코올에 의한 뇌 조직 손상으로부터 보호할 수 있음을 보여준다.

• 대한지역사회영양학회지
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• 제28권2호
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• pp.124-140
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• 2023

Objectives: This study examined the changes in dietary habits, the prevalence of chronic diseases, and mental health problems in the regional areas of the Republic of Korea before and after the COVID-19 pandemic to provide evidence of the status of regional health inequalities. Methods: This study analyzed Korean adults aged 19 or older who participated in the Korea Community Health Survey (n = 686,708) and Consumer Behavior Survey for Foods (n = 19,109) from 2018 to 2020. The participants were classified according to their residence area (Seoul metropolitan area, Metropolitan cities, Provinces); 2018-2019 were defined as before COVID-19, and 2020 as after COVID-19. The dietary behaviors, chronic diseases, and mental health problems were measured using a self-report questionnaire. Results: After COVID-19, the eating-out usage rate in the Seoul metropolitan area and Provinces decreased compared to before COVID-19 (P < 0.001), and when responding that they eat out, the frequency of eating out with household members in the Seoul metropolitan area increased (P = 0.024). The deliveries/takeout usage rate in the Provinces decreased after COVID-19 compared to before (P < 0.001). After COVID-19, the prevalence of obesity decreased in all regions (P < 0.001), and the prevalence of hypertension increased significantly in the Provinces (P = 0.015). The prevalence of diabetes mellitus increased continuously before and after COVID-19 in all regions (P < 0.002). High-risk subjective stress levels increased significantly in the Seoul metropolitan area (P < 0.001), and sleep duration significantly increased in all regions (P < 0.001). Major depressive disorder was reduced significantly in Metropolitan cities (P = 0.042) and Provinces (P < 0.001). Conclusions: After the COVID-19 pandemic, the prevalence of chronic diseases and mental health problems showed regional differences along with changes in dietary habits. It is necessary to reflect the regional differences in dietary habits in future policies resolving regional health inequalities.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2023년도 임시총회 및 춘계학술대회
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• pp.16-16
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• 2023

Metabolomics is the study of global metabolite profiles in a system (cell, tissue, or organism) under a given set of conditions. Metabolomics has its roots in early metabolite profiling studies but is now a rapidly expanding area of scientific research in its own right. In this study, the applications of metabolomics in natural product studies are explored. Ginseng is a well-known herbal medicine and has various pharmacological effects, which include antiaging, anticancer, antifatigue, memory enhancing, immunomodulatory, and stress reducing effects. Metabolomic analysis of organic acids has not been performed for evaluation whether ginseng has been cultivated using conventional or environmental-friendly farming methods. In this study, profiling analysis was conducted for organic acids (OAs) in ginseng roots produced using conventional or environmentfriendly farming methods at five locations in each of five regions. In OA profiles, lactic acid was the most abundant OA in all regions, with the exception for environmentally friendly farmed ginseng in two of the five regions, in which glycolic acid was most abundant OA. OA profiles in all regions showed isocitric acid levels were increased by environment-friendly cultivation, which suggests metabolic differences associated from farming method, and that isocitric acid might be a useful discriminatory biomarker of environmental-friendly and conventional cultivation. The results of the present study suggest metabolomic studies of OAs in ginseng roots might be useful for monitoring whether ginseng has been cultivated using conventional or environmentally friendly farming methods.

• 한국세라믹학회지
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• 제29권11호
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• pp.843-850
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• 1992

The purpose of this study was to describe the heterogeneity effects on Intermediate/Final microstructure in isothermal liquid phase sintering. Several kinds of pore shapes were made by the different in the heterogeneity stress level during Intermediate/Final stage. Specimen with 48% green density especially showed that the local regions of a sintered compact were subject to more rapid shrinkage than the surroundings. This densification limiting factors generally inhibited sintering and made the large isolated crack-like pore in heterogeneous microstructures.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.201-206
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• 2001

This paper presents truss model that can be used to determine the deformation as well as strength of RC members. This model is constituted to address plastic hinge rotation at tile deformation concentrated regions under severe lateral load. The behavior of each element of truss model is evaluated on the basis of stress field analysis. The deformation is obtained by combining element deformations with joint rotation. Initial strength is calculated at the first failure of any element, and strength deterioration after failure depends on the strength reduction of this element. The proposed model will provide useful tools in seismic design of ductility-required members.

• Journal of applied mathematics & informatics
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• 제6권2호
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• pp.631-638
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• 1999

Sensitive testing has been widely employed for many years in connection with the development and evaluation explosives detonation devices and propellants. Perhaps its earliest and possibly most important implementation was in biological studies of dosage mortality and response to drugs. Recently sensitivity experiments has been employed in the evaluation of new materials subject to stress in various environments and in delineanation of unstable combustion regions in chemical propulsion systems. This paper discussed a sta-tistical development of sensitivity testing.