• 대한예방한의학회지
• /
• 제28권2호
• /
• pp.113-130
• /
• 2024

Objectives : This study was conducted to evaluate the cytotoxic protective effects of Jinsimyusaeng-hwan (Modified Ojayeonjong-hwan) against oxidative stress. Methods : 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis-(3-ethyl-benzothiazoline-6-sulfonic acid)(ABTS) radical scavenging activity and ferric reducing ability of plasma (FRAP) method were used to estimate the antioxidant activity of Jinsimyusaeng-hwan. C2C12 myoblasts were used to reevaluate the antioxidant effects. And apoptosis analysis, mitochondrial membrane potential analysis, measurement of intracellular reactive oxygen species levels were conducted to investigate antioxidant activity of Jinsimyusaeng-hwan. Results : In comparison of DPPH free radical and ABTS cationic radical scavenging activity, it increased as the concentration of water extracts of Jinsimyusaeng-hwan(WEJ) and 70% ethanol extracts of Jinsimyusaeng-hwan (EEJ) increased. In the results of comparing the total phenol content and reducing power using the FRAP method, extracts with high total phenol content also showed high reducing power. In comparison of the protective effect against H₂O₂-induced oxidative stress in C2C12 myoblasts, WEJ had no significant effect, but the EEJ inhibited H₂O₂-mediated cytotoxicity in a concentration-dependent manner. The cytotoxic protective effect of EEJ against oxidative stress in C2C12 myoblasts was correlated with their inhibitory effects on H₂O₂-induced apoptosis and cell cycle arrest. In H₂O₂-treated C2C12 myoblasts, the apoptosis inhibitory effects of EEJ were associated with suppression of mitochondrial dysfunction and DNA damage. The protective effect of EEJ against H₂O₂-induced oxidative stress in C2C12 myoblasts were directly related to the inhibition of ROS generation. Conclusion : Jinsimyusaeng-hwan extracts have cytotoxic protective effects against oxidative stress, and it was better in 70% ethanol extract than in water extract.

• 대한치과보철학회지
• /
• 제38권5호
• /
• pp.675-694
• /
• 2000

The purpose of this study was to investigate the displacement of and the stress distribution on the prosthesis, abutment, and its supporting tissues under functional load, and the effect of alteration in root length of 2nd abutment. The 3-dimensional finite element method was used and the finite element models were prepared in which the abutments of left mandibular 5 unit axed partial denture were canine, the 1st pre-molar and the 2nd molar, and the root lengths of canines were as follows. Model I : Root length of canine was 2mm longer than the 1st premolar Model II : Root length of canine was 2mm shorter than the 1st premolar Static compressive force of 300N was applied to connector between 2nd premolar & 1st molar, and then von Mises stress, displacement and reaction force were obtained. The results were as follows : 1. In fixed partial denture, prosthesis under load on pontic was rotated around mesio-distal long axis of it from longual side to buccal, and simultaneously bended in buccal and gingival direction with mesial end deformed in gingival direction and distolingual end in occlusal. 2. Clinical crowns of abutments were bended in the same directions with those in which prosthesis deforms. Due to that, roots of anterior abutments were twisted in counterclockwise with concentration of shear stress on distal or distobuccal sides of their cervices, and that of posterior was in clockwise with concentration of shear stress on mesiobuccal side of it in the same level with anterior abutments. 3. In case that root length of the 2nd abutment was longer than that of the 1st abutment, its displacement and reaction force which means the force tooth exerts on the surrounding periodontal tissues were smaller but shear stress on itself was larger than in the case root length of 2nd abutment was shorter.

• 대한기계학회논문집A
• /
• 제23권6호
• /
• pp.988-1000
• /
• 1999

An experimental study is presented for the effect of number of terms of a pewee series type stress function on stress analysis around a hole in tensile loaded plate. The hybrid method coupling photoelastsic data inputs and complex variable formulations involving conformal mappings and analytical continuity is used to calculate tangential stress on the boundary of the hole in uniaxially loaded, finite width tensile plate. In order to measure isochromatic data accurately, actual photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. For qualitative comparison, actual fringes are compared with calculated ones. For quantitative comparison, percentage errors and standard deviations with respect to percentage errors are caculated for all measured points by changing the number of terms of stress function. The experimental results indicate that stress concentration factors analyzed by the hybrid method are accurate within three percent compared with ones obtained by theoretical and finite element analysis.

• 한국지반환경공학회 논문집
• /
• 제11권8호
• /
• pp.49-55
• /
• 2010

병렬터널의 이격거리가 근접할수록 응력집중으로 인하여 필라(pillar)의 파괴 위험이 큰 만큼 필라의 응력 검토 및 필라의 강도를 고려한 필라의 안정성 평가는 병렬터널의 이격거리 검토 시 매우 중요한 사항이다. 본 연구에서는 필라의 안정성을 구하는 방법 중 하나인 수치해석의 요소크기를 검토하여 필라부 안정성 검토에 대한 체계적인 분석을 제안하였다. 그 결과, 강도응력비는 요소크기에 따른 영향이 크게 없었고, 강도강소법에 의한 안전율은 요소가 작을수록 안전율이 작게 나왔다. 특히 지반이 풍화암인 경우 요소크기에 대한 안전율 값 차이가 크므로 지반이 불량한 경우 요소의 크기를 작게하는 것이 안정적인 결과를 나타냈다.

• Journal of Acupuncture Research
• /
• 제24권3호
• /
• pp.99-109
• /
• 2007

Objectives : The purpose of this study is to observe the anti-oxidative effects of electroacupuncture at Taegye($KI_3$) in rats. Methods : The methods are measures of experimental items including change of body weight, relative liver weight, level of alblumin, total bilirubin, LDL-cholesterol, LDH, GOT and GPT in blood serum, level of SOD, GSH, catalase, NO and MDA concentration in liver, histological change of liver. Results: 1. The $KI_3$-EA group lost weight in the beginning, and gained it gradually. 2. The liver ratio of the $KI_3$-EA group increased compared to the holder group, without any statistical significance. 3. The SOD activity, Glutathione concentration, and Catalase concentration increased, and the NO concentration and MDA concentration decreased in the $KI_3$-EA group significantly, compared to the holder group. 4. $KI_3$-EA group had more similar density to the normal group, than the holder group. Conclusion : The electroacupuncture application on Kb has anti-oxidation effect, by improving the body defence against the oxidation stress- induced cytotoxicity, and by supressing the oxidative liver damage.

• 한국자원식물학회지
• /
• 제21권5호
• /
• pp.395-401
• /
• 2008

Flavonoid는 거의 모든 야채와 과일에 함유된 주요한 구성 성분이며 flavonol은 flavonoid 그룹 중 하나로 우리가 식품으로 섭취하는 대표적인 성분으로는 kaempferol과 quercetin이 알려져 있다. kaempferol과 auercetin은 퇴행성질병의 예방에 효과가 있다고 알려져 있어 식품 첨가물로 사용되고 있다. 본 연구의 목적은 항산화제로도 알려진 kaempferol과 quercetin을 이용하여 다양한 농도에서의 소의 폐혈관내피 세포주에 대한 각각의 산화스트레스 보호효과와 두 가지 물질의 동시 처리 시에 나타날 수 있는 상승효과를 밝히기 위함이다. 1 mM의 $H_{2}O_{2}$를 처리하여 산화스트레스를 가한 세포나 가하지 아니한 세포에서나 모두 kaempferol과 quercetin의 처리로 세포의 활성도가 높았다. 그러나 특히 산화스트레스를 가한 세포에서 항산화물의 산화스트레스 극복효과가 현저하게 나타났다. 항산화물의 농도가 고농도의 경우 오히려 증가된 세포활성도가 저하되는 반응을 보여 너무 높은 농도의 처리는 오히려 항산화효과를 억제할 수 있음을 알 수 있었다. 일반적으로 우리가 섭취하는 식품에는 kaempferol과 quercetin이 함께 포함되어 있으므로 이 두 가지 물질을 일정 비율로 서로 섞은 다음 산화스트레스 처리와 함에 처리하여 조사한 결과 단독으로 처리한 결과와 달리 고농도 조건에서도 세포활성도가 아주 높게 나타났다. 이상의 결과에서 항산화물은 생체에서 일어날 수 있는 많은 산화스트레스 상태를 완화시킬 수 있으나 가장 우수한 효능을 나타낼 수 있는 적정 농도의 조사가 중요하며 특히 각각의 항산화물을 단독으로 사용하는 것 보다 함께 사용하는 것이 상승효과를 나타낼 수 있음을 알 수 있었다.

• 대한조선학회논문집
• /
• 제43권2호
• /
• pp.213-219
• /
• 2006

Low cycle fatigue cracks are mainly detected at discontinuous welded locations with high stresses under repeated cyclic static loads due to cargo leading and unloading. Theoretical and analytical methods have been used for evaluation of local stress and strain which have an effect on a prediction of fatigue life, but those have difficulties of considering stress concentration at notched location and complicated material behavior of welded joint or heat affected zone. Electronic speckle pattern interferometry(ESPI) system is nondestructive and non-contact measurement system which can get the relatively accurate full field strain at critical positions such as welded zone and structural discontinuous location. In this study, local strain was measured on welded cruciform joint by ESPI system and then low cycle fatigue test was performed. Effect of local strain on low cycle fatigue life was examined by measured values using ESPI system. Moreover, experimental fatigue life was compared with established S-N curves using theoretical local strain and stress calculated by Neuber's rule.

• Biomaterials and Biomechanics in Bioengineering
• /
• 제2권4호
• /
• pp.197-206
• /
• 2015

This paper presents three-dimensional finite element method analyses of the distribution of equivalents stress of Von Mises. Induced around a cavity located in the bone cement polymethylmethacrylate (PMMA). The presences and effect of its position in the cement was demonstrated, thus on the stress level and distribution. The porosity interaction depending on their positions, and their orientations on the interdistances their mechanical behaviour of bone cement effects were analysed. The obtained results show that micro-porosity located in the proximal and distal zone of the prosthesis is subject to higher stress field. We show that the breaking strain of the cement is largely taken when the cement, containing the porosities very close adjacent to each other.

• 대한기계학회논문집
• /
• 제17권7호
• /
• pp.1710-1718
• /
• 1993

This paper investigates the problem of a crack approaching two circular holes in an orthotropic infinite plate. The stress intensity factors were obtained by using the modified mapping-collocation method. The present results show excellent agreement with existing solutions for a crack approaching two circular holes in an isotropic infinite plate. In the numerical examples, various types of cross-ply laminated composites were considered. To investigate the effect of orthotropy and geometry(d/R and a/(d-R)) on crack tip singularity, stress intensity factors were considered as functions of the normalized crack length. It is expected that the modified mapping-collocation method can be applied to the analysis of various kinds of cracks existing around the stress-concentration region of composite laminate.

• 한국가시화정보학회지
• /
• 제13권2호
• /
• pp.28-32
• /
• 2015

Blood flow simulations in an realistic carotid bifurcation model with considering wall compliance were carried out to investigate the effect of wall elasticity on the wall shear stress and wall solid stress. Canonical waveforms of flow rates and pressure in carotid arteries were imposed for boundary conditions. Compared to a rigid wall model, we found an increased recirculation region at the carotid bulb and an overall reduction of wall shear stress in a compliant model. Additionally, there was appreciable change of flow rate and pressure wave in longitudinal direction. Both solid and wall shear stress concentration occur at the bifurcation apex.