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        검색결과 93

        61.
        2018.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        본 연구는 고지방 식이로 유발된 내당능 장애 모델의 학습 및 기억력 장애에 대한 스피룰리나 섭취의 개선 효과를 확인하고자 하였다. 당부하 검사(IPGTT)를 통하여 고지방식이를 통한 내당능 장애가 유발되었음을 확인하였고, SP는 HFD 대비 약 20%의 당 내성 개선효과를 나타내는 것으로 나타났다. 고지방 식이로 인지 기능 손상을 유발시킨 동물모델의 Y-maze 및 Morris water maze 시험을 진행한 결과는 SP에서 CND 대비 학습 및 장·단기기억력 장애가 유의한 수준으로 개선됨을 확인하였다. 실험동물의 혈청분석 결과는 스피룰리나 섭취가 일반식이로 전환한 것과 비교하였을 때, HFD 대비 LDLC 감소 및 HTR(HDLC의 비율) 증가를 통한 혈중 콜레스테롤 개선에 효과를 나타냈다. 적출된 뇌와 간 조직을 대상으로 SOD 활성, oxidized GSH 함량 및 MDA 함량을 측정한 결과 스피룰리나 섭취가 뇌조직뿐만 아니라 간 조직에서 항산화 활성을 향상시켜 주는 것도 역시 확인할 수 있었다. 이러한 결과는 고지방 식이를 통한 혈당 상승 및 이로 인한 기억능력 저하에서 스피룰리나 섭취는 CND 수준으로의 개선 효과를 유도할 수 있음을 확인하였다. 또한, 스피룰리나 섭취는 뇌 기능과 직접적으로 연관된 콜린성 시스템 손상에도 CND 대비 AChE 활성에 더 높은 저해효과를 나타냄을 확인하였다. 따라서 본 연구는 스피룰리나가 고지방 식이로 유도된 내당능 장애 모델에서 발생될 수 있는 뇌기능 저하에서 혈중 콜레스테롤 개선 효과, 항산화 효과 및 AChE 저해효과를 통하여, 비만으로 유도될 수 있는 대사성 인지 장애에 대한 개선 소재로의 잠재적인 가능성을 갖는 것으로 판단된다.
        62.
        2018.04 KCI 등재 서비스 종료(열람 제한)
        Erectile dysfunction (ED), also known as impotence, is the inability to attain and sustain an erection firm enough to have sexual intercourse. Frequent ED may be a symptom of health problems including heart disease, obesity, alcoholism, stress, smoking, and depression, that need treatment. This study aimed to effect of complex extract (CPL) including Cornus officinalis on sexual function factor in the erectile dysfunction rat model. The erectile dysfuction rat model was induced by cimetidine (500 ㎎/㎏ in 5% ethanol, oral injection 2 weeks). Rats were oral administered with different concentration of CPL in rat erectile dysfunction model. As a results, sexual function factors (NO, cGMP) significantly improved in CPL treated groups (CPL-300, 600, 900 ㎎/㎏) compared to CON group. Serum testosterone was increased in a dose-dependent manner after CPL treatment. Furthermore, administrations of CPL restored lumen areas of the prostate in the erectile dysfunction rat model. These results indicated that CPL alleviated erectile dysfunction by increasing sexual function factor and testosterone in rat model. CPL could be used to natural treatement for erectile dysfunction. However, further study is required to identify active ingredient and its mechanism of erectile dysfunction.
        63.
        2018.04 서비스 종료(열람 제한)
        This paper presents an improved double diffusion model (DDM) for the alkali silica reaction. By this model we could simulate the diffusion process of alkali both in concrete (macro-scale) and aggregate (micro-scale). As the alkali source, either internal or outside cases can be analyzed through this model. Concrete with different size groups of aggregate distribution also can be analyzed. Numerical simulation is utilized to analyze the ion concentration both inside the concrete and aggregate at different moment of penetration.
        64.
        2018.04 서비스 종료(열람 제한)
        An advanced lumped-mass stick (LMS) model introduced in this paper is to overcome the disadvantages of the conventional lumped mass stick model, such as frequency error and low accuracy of dynamic responses. In order to show the performance of the advanced lumped-mass stick model, the experimental test using shaking table is conducted, considering a scaled four-story frame structure. The material of the frame model is stainless and the total mass of the model is about 39kg. The displacement and acceleration responses resulted from the advanced LMS model are compared with those of experimental results, including the response results of the conventional LMS model of the frame model.
        65.
        2018.03 KCI 등재 서비스 종료(열람 제한)
        본 논문에서는 지점부 경계조건을 고려하여 단순보의 유한요소모델을 개선하는 기법을 제안하였다. 기존의 유한요소모델개선 기법은 주로 가속도 응답으로부터 추정된 동특성(고유진동수, 모드형상)을 이용하여 유한요소모델을 개선하였다. 이렇게 개선된 유한요소모델은 실제 구조물의 정적응답을 예측하기 어렵고, 잘못된 구조물의 물성치를 추정하는 문제가 발생한다. 제안된 기법은 먼저, 구조물의 처짐과 지점부 회전변위를 계측하여 지점부 경계조건을 간략화한 유한요소모델의 회전 스프링 강성을 정량적으로 추정한다. 회전 스프링 강성이 개선된 유한요소모델과 구조물의 동특성을 사용하여 구조물의 물성치를 추정함으로써 최종 개선된 유한요소모델을 구축된다. 제안된 유한요소 모델 개선 기법과 기존 유한요소모델개선 기법을 수치해석 시뮬레이션을 통하여 비교 및 검증하였다.
        66.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        Background: A critical features of Alzheimer’s disease (AD) is cognitive dysfunction, which partly arises from decreased in acetylcholine levels. AD afftected brains are characterized by extensive oxidative stress, which is thought to be primarily induced by the amyloid beta (Aβ) peptide. In a previous study, Cinnamomum loureiroi tincture inhibited acetylcholinesterase (AchE) activity. That study identified AChE inhibitor in the C. loureiroi extract. Furthermore, the C. loureiroi extract enhanced memory in a trimethyltin (TMT)-induced model of cognitive dysfunction, as assessed via two behavioral tests. Rosa laevigata extract protected against oxidative stress-induced cytotoxicity. Administrating R. laevigata extracts to mice significantly reversed Aβ-induced learning and memory impairment, as shown in behavioral tests. Methods and Results: We conducted behavioral to examine the synergistic effects of C. loureiroi and R. laevigata extracts in inhibiting AChE and counteracting TMT-induced learning and memory losses. We also performed biochemical assays. The biochemical results showed a relationship between increased oxidative stress and cholinergic neurons damage in TMT-treated mice. Conclusions: A diet containing C. loureiroi and R. laevigata extracts ameliorated learning and memory impairments in the Y-maze and passive avoidance tests, and exerted synergistic inhibitory effect against AChE and lipid peroxidation.
        67.
        2017.11 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        대나무 죽력의 ACE 저해효과와 마우스모델에서의 혈행 개선 효과를 보았다. 혈전용해능에서 청국장추출물은 2.56 unit, 미정제죽력에서 4.71 unit, 정제죽력에서 4.32 unit를 나타내어 모두가 plasmin 보다 유의하게 높은 활성이 높고, ACE 활성 저해 효과에서는 죽력 원액, 미정제 죽력과 정제 죽력에서 각각 70.25%, 69.01%, 68.23%로 대조군으로 사용된 청국장이 26.56%으로 나타나 높은 억제효과를 보였다. 마우스모델시험에서 고지방식이군과 함께 고지방식이군+ 정제죽력 0.01%와 0.05%를 투여, 혈청 중 지질변화에서 triglyceride의 함량은 고지방식이군이 일반식이군(271.1 mg/dL)에 비해 314.4 mg/dL로 증가하였고, 고지방식이+죽 력 0.01%군은 301.5 mg/dL로 나타났으며, 고지방식이+죽 력 0.05%군은 289.2 mg/dL으로 유의하게 중성지질이 감소를 나타내었고, total-cholesterol 함량은 327.2 mg/dL로 증가 하였으며, 고지방식이+죽력 0.01%군은 311.9 mg/dL로 나타났으며, 고지방식이+죽력 0.05%군은 293.7 mg/dL로 고 지방식이군에 비교, 유의하게 total-cholesterol이 감소세를 나타내었다. 한편 HDL-cholesterol은 일반식이군이 206.0 mg/dL로 가장 높은 값을 나타내었으며, 고지방식이+죽력 0.01%군 196.6 mg/dL, 고지방식이+죽력 0.05%군 189.2 mg/dL, 고지방식이군 162.2 mg/dL순으로 나타났고, 죽력첨 가군 0.01%군과 0.05%군간의 유의성은 없었다. 혈류개선 효과에서는 고지방식이에 비하여 고지방식이+죽력 0.05% 군이 고지방식이군, 고지방식이+죽력 0.01%군보다 모두 유의하게 빠르게 모세관을 통과하여 빠른 혈액 유동성을 나타내었다. 혈소판응집 억제능에서는 고지방식이군의 경우 대조군인 일반식이군에 비해 혈소판 응집이 증가한 반면 고지방식이+죽력 0.01%군과 고지방식이+죽력 0.05%군은 고지방식이군에 비해 혈소판응집이 억제되는 것으로 나타났다.
        68.
        2017.04 서비스 종료(열람 제한)
        In this paper, the finite element model updating method of the PSC bridge based on the static and dynamic data is verified through field experiment. The proposed method consists of two steps. First, update the rotational stiffness of the supports using the deflection and rotational displacement measurements that occur when the moving loads pass through the bridge. The stiffness of each member is updated by using the dynamic characteristics estimated from the acceleration measured by the ambient vibration test. The finite element model updated by the proposed method can predict the static and dynamic behavior of actual bridges through field experiment.
        69.
        2017.04 서비스 종료(열람 제한)
        Finite Element Model(FEM) is generally used for evaluating a bridge construction. But it has discrepancy between measured data of real structure and analysis value of FEM. Therefore, FEM has to reflect characteristics of real structure using FEM updating. Static and dynamic data used to FEM updating update different characteristic of FEM. However, since it is difficult to measure static data, static information extracted from dynamic measured data can be used. In this study, new concept, LDFAC, using Lateral Distribution Factor(LDF) extracted from dynamic data is introduced as static information. As the analysis results, it is verified to get more accurate updating value when updating FEM with LDFAC.
        70.
        2017.04 서비스 종료(열람 제한)
        In this study, dynamic characteristics were analyzed by field measurement and experiment mode analysis on a vertical axis wind turbine with resonance issue, and dynamic model modification was also carried out by concrete filling inside the steel tower. Finally, the overall power generation and economic efficiency due to the extension of the range of rotor rotational speed was also analyzed.
        71.
        2016.07 KCI 등재 서비스 종료(열람 제한)
        To prevent increasing instances of heat-related illnesses due to heat waves generated by climate change, a customized thermal environment index should be developed for outdoor workers. In this study, we conducted sensitivity analysis of the Masan harbor during a heat wave period (August 9th to 15th, 2013) using the MENEX model with metabolic rate and clothing-insulation data, in order to obtain realistic information about the thermal environment. This study shows that accurate input data are essential to gather information for thermophysiological indices (PST, DhR, and OhR). PST is sensitive to clothing insulation as a function of clothing. OhR is more sensitive to clothing insulation during the day and to the metabolic rate at night. From these results, it appears that when exposed to high-temperature thermal environments in summer, wearing highly insulated clothing and getting enough rest (to lower the metabolic rate) can aid in preventing heat-related illnesses. Moreover, in the case of high-intensity harbor work, quantification of allowed working time (OhR) during heat waves is significant for human health sciences.
        72.
        2016.05 KCI 등재 서비스 종료(열람 제한)
        본 연구는 단경간 교량의 정적하중입력/변위출력관계를 이용한 새로운 교량 유한요소모델 개선 방법을 제안하였고, 실내 모형교량 실험을 통해 검증하였다. 기존의 유한요소모델개선기법은 실험으로부터 얻어진 모드계수와 유한요소모델로부터 예측된 모드계수가 유사해 지도록 유한요소모델을 개선하는데, 이 과정에서 구조계의 질량행렬에 대한 가정을 필요로 한다. 제안된 기법은 질량행렬을 가정하지 않고, 오 히려 질량행렬 추정을 가능하게 하는 장점을 가진다. 제안된 기법은 두 단계로 구성된다. 첫째, 정적 하중입력-변위응답으로부터 강성행렬을 개선하고, 둘째, 실측된 고유진동수를 이용하여 질량행렬을 개선한다. 실험검증을 위하여 실내 모형교량을 제작하였고, 제안된 기법을 이용하 여 모형교량의 탄성계수를 추정하였으며, Universal Testing Machine으로 부터 얻어진 탄성계수와 비교하였다. 또한 기존의 유한요소모델개 선기법으로 추정된 탄성계수와 비교하였다. 실험의 결과들로부터 제안된 기법이 합리적으로 탄성계수와 질량밀도를 추정하는 것이 관찰되었 고, 기존의 유한요소모델개선기법은 고차모드를 사용했을 때 상대적으로 큰 오차를 주는 것이 관찰되었다. 추가적으로 유한요소모델링 오차 에 대하여 토의하였다.
        73.
        2016.04 서비스 종료(열람 제한)
        Interest in seismic performance evaluation is increased due to various earthquake in the world. Many studies about fragility analysis of structure are performing which is based on probability analysis of failure for infrastructures maintenance. In this study, probability of failure for a numerical model of prototype square-shape reinforced concrete column was calculated in accordance with amplitude of seismic ground motion. The numerical model was updated based on results from shake table tests. The probability of failure will be used for comparing with that for scaled models. The difference of fragilities from prototype and scaled model can be confirmed by the comparing in a further study.
        74.
        2016.04 서비스 종료(열람 제한)
        High speed railway bridges should be strictly maintained due to its social importance. However, There are many problems to execute loading test for precision safety diagnosis. A numerical experiment with a numerical model which is updated for reflecting characteristics of an existing bridge can be useful for high speed railway bridge maintenance. Moreover, more efficient maintenance can be possible if only ambient vibration is needed for numerical model updating process. In this study, a numerical model updating process is introduced in which only ambient vibration is enough to execute the process. Also, the usability of updated numerical model is verified by comparing measured and analyzed acceleration.
        75.
        2016.04 서비스 종료(열람 제한)
        The bridges with damage can be a huge threat to human society. However, AASHTO (2012) and Korean Highway Bridge Design Code (2012) do not account for dynamic impacts for bridge column design under the impact loading. It recommends static force for bridge column design due to high computational cost and analysis time. In this study, in order to reduce the computational cost and time for the dynamic analysis, low dimensional model for the dynamic analysis was developed and residual displacements were compared with direct impact analysis.
        76.
        2016.02 KCI 등재 서비스 종료(열람 제한)
        본 논문은 빛의 조명으로 defense 게임 플레이에 대한 캐릭터 표면모델을 시뮬레이션하는 데 프레넬의 수학적 모델을 제안한다. 여기서 illumination은 게임에서 사용되는 캐릭터표면 모델에 도달하는 빛의 양을 결정하는 프로세스를 나타낸다. 캐릭터 표면의 shader는 일반적으로 빛이 triangle에 반영하는 방법 즉 예측하는 수학적 모델을 사용한다. shading은 일반적으로 색상과 빛의 강도를 결정하기 위해 사용되는 방법인데, viewer에서 본다면 게임 캐릭터의 표면 위에 각 픽셀에 대한 반사결과를 나타낸다. 여기서 제안 모델은 반사와 투과 계수를 계산하여 실제 게임 플레이를 하면서 프레넬 방정식으로 시뮬레이션 결과를 비교하였다.
        77.
        2015.10 서비스 종료(열람 제한)
        A Finite-Element (FE) model updating method is widely used for identifying structural integrities such as support conditions and material properties. However, it is still difficult to properly estimate support conditions using limited number of data. This study proposed a novel FE model updating method, which can identify support conditions by adding artificial springs at the supports, and by measuring the rotational angles of the supports.
        78.
        2015.04 서비스 종료(열람 제한)
        This paper presents a laboratory validation for a Finite Element model updating method using moving vehicle input-deflection output measurements. In conventional FE model updating, a few natural frequencies measured from field experiments have been used to update the FE model based on the assumption that the mass matrix is known accurately. The proposed approach can update the stiffness matrix without the assumption by using static input-output measurements and can even update the mass matrix by using a few natural frequencies obtained from dynamic measurements. Laboratory experiments were carried out for a scaled model of Samseung Bridge located in the test road of Korea Highway Corporation. For a simplicity of experiments, a mass (11kgf) was located in four different locations on the deck and two deflections were measured by laser displacement meters: one at the center girder, and the other in at the outer girder, both in mid-span. Results showed that the proposed methods was capable to estimate Young's Modulus and the mass density of the model bridge accurately while natural-frequency-based updating may result in significant error when higher modes (2nd, 3rd) were used.
        79.
        2015.04 서비스 종료(열람 제한)
        This study proposes a FE model updating strategy based on data fusion of acceleration and angular velocity. The use of acceleration and angular velocity gives richer information than the sole use of acceleration, allowing the enhanced performance particularly in determining the boundary conditions. A numerical simulation is presented to demonstrate the proposed FE model updating approach using the data fusion.
        80.
        2015.03 KCI 등재 서비스 종료(열람 제한)
        The finite element (FE) model updating is a commonly used approach in civil engineering, enabling damage detection, design verification, and load capacity identification. In the FE model updating, acceleration responses are generally employed to determine modal properties of a structure, which are subsequently used to update the initial FE model. While the acceleration-based model updating has been successful in finding better approximations of the physical systems including material and sectional properties, the boundary conditions have been considered yet to be difficult to accurately estimate as the acceleration responses only correspond to translational degree-of-freedoms (DOF). Recent advancement in the sensor technology has enabled low-cost, high-precision gyroscopes that can be adopted in the FE model updating to provide angular information of a structure. This study proposes a FE model updating strategy based on data fusion of acceleration and angular velocity. The usage of both acceleration and angular velocity gives richer information than the sole use of acceleration, allowing the enhanced performance particularly in determining the boundary conditions. A numerical simulation on a simply supported beam is presented to demonstrate the proposed FE model updating approach.
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