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      • KCI등재

        Synthesis, Phase Behavior, and Simulated In vitro Degradation of Novel HTPB-b-PEG Polyurethane Copolymers

        Yan-Ling Luo,Yan Miao,Feng Xu 한국고분자학회 2011 Macromolecular Research Vol.19 No.12

        Two types of polyurethanes with alternating and random block architectures, hydroxyl-terminated liquid polybutadiene and poly(ethylene glycol) block copolymers (HTPB-alt-PEG and HTPB-co-PEG), were synthesized using a coupling reaction route between the hydroxyl groups and the isocyanate groups. The chemical and crystal structures were characterized using Fourier transform-infrared spectroscopy (FTIR) and X-ray diffraction, while phase behavior was examined using scanning electron microscopy (SEM) and differential scanning calorimetry. The biodegradation in a simulated human body fluid was investigated through mass loss, SEM, and FTIR. The experimental results indicated that all of the polyurethane samples bore the microphase separation structure, and the separation degree depended on the sequence structure and molecular weight (MW) of PEG and further affected their in vitro degradation. The driving force was related to the restricted movement of the molecular segments, the crystallization of the soft/hard phases, and/or the hydrogen bonding interactions between the hard segments. The surface morphological change of the degraded samples further demonstrated that the degradation became serious as the PEG MW increased and that the random block copolymers decomposed more easily than the alternating copolymers. The block polymer materials are expected to be incorporated into specific applications in related biomedical fields.

      • KCI등재

        Effect of Turbulent Fluctuation on Settling Behavior of Dredged Slurry in Sheared Condition

        Miao-miao Song,Gui-zhong Xu,Jie Yin,Wei-juan Geng,Zhi-yan Zhou,Cheng-chun Qiu 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.4

        For the land shortage problem upon the city development in coastal areas, it is of great importance to improve the overall understanding of the settlement behavior of dredged slurry and determine the required site water storage capacity as well as the mechanical properties of the newly formed dredged slurry. This paper presents an experimental investigation on the effect of turbulent fluctuation on the settling behavior of dredged slurry in sheared condition via a self-developed testing apparatus namely double cylinder settling column. Test results showed that the settling velocity of the soil-water interface initially increased then decreased with the increasing rotation speed of the inner column. The interface would disappear and a stable suspended layer was observed when the rotation speed was greater than 20 rad/min, where water contents and grain composition were not changed over the depth. The particle content was closer to that of the original sample as the rotation speed kept increasing in the suspended layer. It was found that the stabilized flocs were gradually broken down by the turbulence effect existing in the sheared slurry. Moreover, the stabilized flocs were losing the stability gradually as the flowing velocity increased till 10 rad/min and the floc structure was broken down completely once the flowing velocity was greater than 20 rad/min.

      • Normal Estimation for Mass Point Clouds of Irregular Model in the 3D Reconstruction based on Fuzzy Inference

        Liu Yan-ju,Jiang Jin-gang,Miao Feng-juan,Tao Bai-rui,Zhang Hong-lie 보안공학연구지원센터 2014 International Journal of Grid and Distributed Comp Vol.7 No.5

        This paper presents a fuzzy normal estimate for mass point clouds of irregular models in reconstruction. The irregular model is complex object that some part is smooth and some parts are irregular including sharp features. Therefore, we put kNN and curvature of mass point clouds to fuzzy inference system to divide the kind of point clouds and the output of FIS can determine which part of tooth point clouds belong to. For different kinds point clouds, corresponding algorithm is given. Point clouds in the smooth area are estimated normal by PCA directly and ones in other regions of thin or sharp area are estimated by checker and attach points. This method is simpler than those complex methods used on the whole point clouds directly. The experiment results show that much time is saved and surface reconstruction is very fine than PCA and WLOP.

      • KCI등재

        A Back Propagation Neural Network with Double Learning Rate for PID Controller in Phase-Shifted Full-Bridge Soft-switching Power Supply

        Yan-Ming Cheng,Cheng Liu,Jing Wu,He-Miao Liu,Il-Kyoo Lee,Jing Niu,조주필,구경완,Min-Woo Lee,우덕근 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.6

        This paper mainly focuses on the control strategy for phase-shifting full-bridge soft switching electrolytic silver power supply based on Zero Voltage Switching (ZVS) soft switching technology. Taking into consideration the low performance of traditional PID control for phase-shifting full-bridge soft-switching, this paper introduce a PID improved by Back Propagation (BP) neural network with one single learning rate which is used to calculate weights from the input layer to the hidden layer and weights from the hidden layer to the output layer. After testing, it is found that setting independent learning rate for calculation of weights from the input layer to the hidden layer and weights from the hidden layer to the output layer which will not have an adverse eff ect on the design of the controller. Instead, the learning rate can be set according to the respective characteristics of the weights between the two layers, which is called double learning rate BP neural network PID. The simulation results indicate that compared with the single learning rate BP neural network PID control, the double learning rate BP neural network control has higher response speed, less over-shoot, short time to enter the steady state and strong immunity.

      • KCI등재

        Characterization and Mechanism Analysis of Flexible Polyacrylonitrile-Based Carbon Nanofiber Membranes Prepared by Electrospinning

        Miao Yu,Binjie Xin,Zhuoming Chen,Yan Liu 한국섬유공학회 2023 Fibers and polymers Vol.24 No.12

        Carbon nanofiber membranes have a wide range of applications in energy and environmental fields with excellent thermal stability, electrical conductivity, and chemical resistance. Electrostatic spinning is a simple and effective technique to prepare nanofiber membranes; however, electrostatically spun carbon nanofiber membranes tend to be brittle, which is limiting the application of carbon nanofiber membranes. Herein, flexible carbon nanofiber (FCNF) membranes were prepared in this study by a simple procedure of electrostatic spinning, pre-oxidation, and carbonization. During the high-temperature carbonization process, tetra-butyl titanate (TBT) is transformed into TiO2 grains. The average diameter of FCNF rose with increasing the proportion of TBT. The stress–strain curves showed the best flexibility of FCNF-1.5. The grain size of TiO2 increased to 4.5 nm when carbonized at 1000 °C. TiO2 was shown to improve flexibility by relieving the stress concentration of cracks on the fiber surface, thus reducing the fracture of the produced FCNF.

      • KCI등재

        Beneficial effects of natural Jeju groundwaters on lipid metabolism in high-fat diet-induced hyperlipidemic rats

        Yan-chao Wang,Jin-miao Lu,Hui-zi Jin,Ai-niu Ma,Jin-yang Zhang,Nian Gong,Qi Xiao,Bin Zhu,Ying-fang Lv,Na Yu,Wei-dong Zhang,Yong-xiang Wang 한국영양학회 2014 Nutrition Research and Practice Vol.8 No.2

        BACKGROUND: Groundwater is believed to possess many beneficial effects due to its natural source of various minerals. In this study, we examined the effects of natural Jeju groundwater S1 (SamdasooTM), S2 and S3 pumped up from different locations of Jeju Island, Korea, along with local tap water, on body weight gain, serum lipids and lipoproteins, and liver histopathology in high-fat diet-induced hyperlipidemic rats. MATERIALS/METHODS: Rats were randomly and equally divided into 6 groups. Different water samples were supplied to the hyperlipidemic rats as their daily drinking water and the widely-used anti-hyperlipidemic drug simvastatin was used as a positive control. Body weight, serum lipids and lipoproteins were measured weekly. Liver weight, liver index and liver histopathology were examined after the execution of the rats. RESULTS: After drinking Jeju groundwaters for two months, S2 but not S3 significantly reduced weight growth and serum triglycerides levels and increased high density lipoprotein-C (HDL-C) without affecting total cholesterol or LDL-C. S1 and particularly S2 significantly reduced the severity of liver hypertrophy and steatosis. All Groundwaters had much higher contents of vanadium (S3>S2>S1>>tap water) whereas S1 and S2 but not S3 markedly blocked autoxidation of ferrous ions. CONCLUSION: Jeju Groundwater S1 and particularly S2 exhibit protective effects against hyperlipidemia and fatty liver and hypothesize that the beneficial effect of Jeju Groundwaters may be contributed from blockade of autoxidation of ferrous ions rather than their high contents of vanadium.

      • KCI등재

        Incremental forming of hydraulic supports: a numerical and experimental study of thickness distribution

        Miao Shang,Yan Li,Kuangyu Chen,Mingshun Yang,Xingbai Zhao,Kaixin Nie 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

        The incremental forming technology has enormous potential in manufacturing sheet parts. However, non-uniform thickness distribution is a common technical existing issue in forming thin-walled parts using this technology. The use of hydraulic supports has been a realistic, promising solution to this issue. Based on hydraulically-supported incremental forming technology, a variety of strategies were proposed in this article for hydrostatic and variable pressure supports respectively. For each supporting strategy, the thickness distribution and materials flow laws in various forming regions were explored. Experimental and simulation results indicate that when the hydraulic pressure is less than 1.8 bar, the thickness distribution of the hydrostatic-supports is significantly better than that of conventional incremental forming, and the thickness distribution of the variable-pressure supports may be better than that of the hydrostatic-support. The hydraulically-supported incremental forming technology has an potential of enhancing enhance the thickness distribution performance and forming performance of thin-walled parts.

      • KCI등재

        Relationship Between Dry Ports and Regional Economy: Evidence from Yangtze River Economic Belt*

        Yan Feng LIU,Chong Bae LEE,Guan Qiu QI,Kum Fai YUEN,Miao SU 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.5

        With the evolution of containerization and globalization of supply chains, aspects of port functions have made the transition from the sea to the inland region that forms the dry port. To explore the relationship between dry ports and regional economic development, this study uses a gravity model and forecast model to analyze 1,040 observations in 104 cities (22 dry port cities) along the Yangtze River Economic Belt (YREB) from 2008 to 2017. The model includes economic variables, logistics variables, foreign relations variables, and human capital variables. It was found that the dry port is positively correlated with trade volume. Compared with a city without a dry port, the trade volume of a city with a dry port will increase 0.099 times. It can be concluded that a dry port is crucial for the economic development of the YREB. It was also found that per capita GDP as an economic variable, road area and rail number as logistics variables, and foreign relation variables are positively correlated with trade volume, while the human capital variable has no significant effect on trade volume. In addition, governmental policy implications are addressed from the aspects of dry port and industry cluster caused by foreign investment.

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