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Regular truss structure model equivalent to continuum structure

International Journal of Agricultural and Biological Engineering 2015年第5期8卷 151-161页

作者： won Choi JeongJae lee Seongsoo Yoon Department of Rural Systems Engineering College of Agriculture and Life SciencesSeoul National UniversitySeoul 151-921South Korea Department of Rural Systems Engineering Research Institute of Agriculture and Life SciencesCollege of Agriculture and Life SciencesSeoul National UniversitySeoul 151-921South Korea Department.of Agricultural and Rural Engineering College of AgricultureLife and Environments SciencesChungbuk National UniversityChungbuk 362-763South Korea

It is difficult to solve the structural problems related to agricultural engineering,due to the wide ranges of the means of related variables and complex structural *** these reasons,discrete models are required that are able to replace or simplify solid structure components used in traditional analysis ***,the objective of this study was to develop a regular truss structure model that behaves the same way as a solid *** was assumed that if a unit element consists of truss elements with each hinge at the end of the element and the size of the element is infinitesimal,the stress distribution and displacement field will be constant throughout the domain of the unit ***,the behavior of the truss element was assumed to be in a linear state in a two-dimensional *** law of energy conservation,based on the theory of elasticity,was applied to determine the equilibrium conditions between discretized and solid *** restrictive condition that we obtained revealed that applications are limited to only ideal elastic materials with a Poisson’s ratio of 1 to *** volumetric ratio of the equivalent truss to the continuum structures was 3:1,regardless of the size or number of the *** calculate the internal stress and strain of the unit element,the geometric relationships of each truss member,which has its own role against different stress directions,were *** calculated von Misses stresses were used to verify this *** concentrations,as explained based on Saint Venant’s principle,were also observed in the equivalent truss structure *** main stress paths,indicating the areas where reinforcement bars should be placed,were successfully shown without the requirement that each element be transformed in the direction of principal stress;this was done by eliminating elements with only compressive and near-zero stresses.

关键词： structural analysis regular mesh equivalent truss structure model discretized element energy method

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Thermal-environment characteristics and comfort of combined radiant-floor (Korean heating system ondol) and convective cooling system

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Journal of Central South University 2013年第12期20卷 3589-3603页

作者： lee Kang-Guk HONG won-Hwa School of Architecture Kyungpook National University

The thermal-environment characteristics of the existing forced-convection cooling system were compared with those of the convective cooling system, which combined the radiant-floor cooling system using floor-heating panel typically applied to apartments in South Korea with the forced-convection cooling system using improved fan coil unit. The subjective warm/cool-feeling responses to the combined radiant-floor and convective cooling system in the questionnaire survey conducted among the test subjects were analyzed to establish the basic data for the combined cooling system. The results show that in the thermal-equilibrium condition, the vertical air temperature difference in the model living room is larger in the forced-convection-cooling condition. Most of the subjects feel a proper warm/cool feeling on their entire body, but they feel colder on the foot and lower body in the combined-cooling condition.

关键词： convection cooling temperature ondol thermal comfort fan coil unit combined cooling system

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Preparation of TiAlN/ZrN and TiCrN/ZrN multilayers by RF magnetron sputtering

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中国有色金属学会会刊：英文版 2009年第4期19卷 795-799页

作者： Jong-Kook lee G won-Seung YANG Department of Advanced Materials Engineering Chosun University BK21 Education Center of Mould Technology for Advanced Materials and Parts Chosun University

Titanium-based nitride coatings on cutting tools,press molds and dies can be used to prolong their life cycle because of their superior corrosion and oxidation ***/ZrN and TiCrN/ZrN multilayer coatings were prepared by RF magnetron sputtering,and their microstructural evolution and corrosion resistance during heat treatment were *** TiAlN/ZrN and TiCrN/ZrN multilayer coatings are degraded by heating up to 600 ℃ with the formation of oxides particles on the *** the heat treatment,the TiCrN/ZrN and TiAlN/ZrN multilayer coatings show the lowest corrosion current density and the highest polarization resistance at temperature range of 400-500 ℃.Consequently,the TiAlN/ZrN and TiCrN/ZrN multilayer coatings show good corrosion resistance at temperature range of 400-500 ℃ during heating.

关键词：射频磁控溅射溅射制备氮化锆多层膜钛铝耐腐蚀性腐蚀电流密度

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Significance of adverse outcome pathways in biomarker-based environmental risk assessment in aquatic organisms

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Journal of Environmental Sciences 2015年第9期27卷 115-127页

作者： Jin Wuk lee Eun-Ji won Sheikh Raisuddin Jae-Seong lee Department of Biological Science College of Science Sungkyunkwan University Department of Medical Elementology and Toxicology Hamdard University

In environmental risk assessments（ERA）, biomarkers have been widely used as an early warning signal of environmental contamination. However, biomarker responses have limitation due to its low relevance to adverse outcomes（e.g., fluctuations in community structure, decreases in population size, and other similar ecobiologically relevant indicators of community structure and function）. To mitigate these limitations, the concept of adverse outcome pathways（AOPs） was developed. An AOP is an analytical, sequentially progressive pathway that links a molecular initiating event（MIE） to an adverse outcome. Recently, AOPs have been recognized as a potential informational tool by which the implications of molecular biomarkers in ERA can be better understood. To demonstrate the utility of AOPs in biomarker-based ERA, here we discuss a series of three different biological repercussions caused by exposure to benzo（a）pyrene（Ba P）, silver nanoparticles（Ag NPs）, and selenium（Se）. Using mainly aquatic invertebrates and selected vertebrates as model species, we focus on the development of the AOP concept. Aquatic organisms are suitable bioindicator species whose entire lifespans can be observed over a short period; moreover, these species can be studied on the molecular and population ***, interspecific differences between aquatic organisms are important to consider in an AOP framework, since these differences are an integral part of the natural *** development of an environmental pollutant-mediated AOP may enable a better understanding of the effects of environmental pollutants in different scenarios in the diverse community of an ecosystem.

关键词： Adverse outcome pathway Biomarker Omics Environmental risk assessment Aquatic organisms Interspecific difference

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Efficient photovoltaic effect in graphene/h-BN/silicon heterostructure self-powered photodetector

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Nano Research 2021年第6期14卷 1967-1972页

作者： Ui Yeon won Boo Heung lee Young Rae Kim won Tae Kang Ilmin lee Ji Eun Kim Young Hee lee Woo Jong Yu Department of Electrical and Computer Engineering Sungkyunkwan UniversitySuwon16419Republic of Korea Center for Integrated Nanostructure Physics Institute for Basic Science(IBS)Suwon16419Republic of Korea

Graphene(Gr)/Si-based optoelectronic devices have attracted a lot of academic attention due to the simpler fabrication processes,low costs,and higher performance of their two-dimensional(2D)/three-dimensional(3D)hybrid interfaces in Schottky junction that promotes electron-hole ***,due to the built-in potential of Gr/Si as a photodetector,the Iph/Idark ratio is often hindered near zero-bias at relatively low illumination *** is a major drawback in self-powered *** this study,we have demonstrated a self-powered van der Waals heterostructure photodetector in the visible range using a Gr/hexagonal boron nitride(h-BN)/Si structure and clarified that the thin h-BN insertion can engineer asymmetric carrier transport and avoid interlayer coupling at the *** dark current was able to be suppressed by inserting an h-BN insulator layer,while maintaining the photocurrent with minimal decrease at near *** a result,the normalized photocurrent-to-dark ratio(NPDR)is improved more than 104 ***,both Iph/Idark ratio and detectivity,increase by more than 104 times at−0.03 V drain *** proposed Gr/h-BN/Si heterostructure is able to contribute to the introduction of next-generation photodetectors and photovoltaic devices based on graphene or silicon.

关键词： graphene hexagonal boron nitride van der Waals heterostructure self-powered Research

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Analyses on performances of heat and multilayer reflection insulators

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Journal of Central South University 2012年第6期19卷 1645-1656页

作者： lee Moo-jin lee Kang-guk SEO won-duck School of Architecture Kyungil UniversityGyeongsan 702701Korea Research Center for Urban Affair Kyungil UniversityGyeongsan 702701Korea Department of Architectural Design Joongbu UniversityGeumsan-gun 701140Korea

This research was conducted to study the performances of the heat and multilayer reflection insulators used for buildings in South Korea to realize eco-friendly, low-energy-consumption, green construction, and to contribute to energy consumption reduction in buildings and to the nation＇s greenhouse gas emission reduction policy （targeting 30% reduction compared to BAUCousiness as usual） by 2020）. The heat insulation performance test is about the temperatures on surfaces of test piece. The high air temperature and the low air temperature were measured to determine the overall heat transfer coefficient and thermal conductivity. The conclusions are drawn that the heat transmission coefficients for each type of existing reflection insulator are： A-1 （0.045 W/（m-K））, A-2 （0.031 W/（m.K））, A-3 （0.042 W/（m.K））, A-4 （0.078 W/（m.K））, and the average heat conductivity is 0.049 W/（m-K）; The heat conductivity for each type of Styrofoam insulator are 0.030 W/（m.K） for B-l, 0.032 W/（m-K） for B-2, 0.037 W/（m＇K） for B-3, 0.037 W/（m.K） for B-4, and the average heat conductivity is 0.035 W/（m＇K） regardless of the thickness of the insulator; The heat conductivity values of the multilayer reflection insulators are converted based on the thickness and type C-1 （0.020 W/（m.K））, C-2 （0.018 W/（m.K））, C-3 （0.016 W/（m.K））, and C-4 （0.012 W/（m.K））; The multilayer reflection insulator keeps the indoor-side surface temperature high （during winter） or low （in summer）, enhances the comfort of the building occupants, and conducts heating and moisture resistance to prevent dew condensation on the glass-outer-wall surface.

关键词： heat reflection insulator multilayer reflection insulator overall heat transfer coefficient thermal conductivity nonflammability vapor permeability eco-friendly construction

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Security Enhanced Anonymous User Authenticated Key Agreement Scheme Using Smart Card

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Journal of Electronic Science and Technology 2018年第1期16卷 45-49页

作者： Jaewook Jung Donghoon lee Hakjun lee Dongho won Department of Computer Engineering Sungkyunkwan UniversityGyeonggi-do 16419

Nowadays, the password-based remote user authentication mechanism using smart card is one of the simplest and convenient authentication ways to ensure secure communications over the public network environments. Recently, Liu et al. proposed an efficient and secure smart card based password authentication scheme. However, we find that Liu et al.’s scheme is vulnerable to the off-line password guessing attack and user impersonation attack. Furthermore, it also cannot provide user anonymity. In this paper, we cryptanalyze Liu et al.’s scheme and propose a security enhanced user authentication scheme to overcome the aforementioned problems. Especially, in order to preserve the user anonymity and prevent the guessing attack, we use the dynamic identity technique. The analysis shows that the proposed scheme is more secure and efficient than other related authentication schemes.

关键词： Authentication off-line password guessing attack smart card user anonymity

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Porously Reduced 2-Dimensional Bi_(2)O_(2)CO_(3) Petals for Strain-Mediated Electrochemical CO_(2) Reduction to HCOOH

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Energy & Environmental Materials 2024年第1期7卷 215-221页

作者： won Seok Cho Dae Myung Hong Wan Jae Dong Tae Hyung lee Chul Jong Yoo Donghwa lee Ho won Jang Jong-Lam lee Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)Pohang Gyungbuk 37673Korea Department of Materials Science and Engineering Research Institute of Advanced Materials Seoul National UniversitySeoul 08826Korea

Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film in aqueous carbonate solution at room *** the electrochemical reduction process,the BOC petals transform to reduced BOC(R-BOC)consisting of individual BOC and Bi *** mismatch between both domains induces biaxial strain at the *** functional theory calculations suggest that the tensile strain on the Bi domain stabilizes the*OCHO intermediate,reducing the thermodynamic barrier toward CO_(2)conversion to *** with the thermodynamic benefit and the unique nanoporous petal-shaped morphology,R-BOC petals have a superior Faradaic efficiency of 95.9%at-0.8 V_(RHE)for the electrochemical conversion of CO_(2)to *** work demonstrates that the spontaneously formed binary phases with desirable lattice strain can increase the activity of bismuth catalysts to the CO_(2)reduction reaction;such a strategy can be applicable in design of various electrocatalysts.

关键词： bismuth carbon dioxide reduction formic acid heterointerfaces strain

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Bojungbangdocktang inhibits vascular endothelial growth factor induced angiogenesis via blocking the VEGF/VEGFR2 signaling pathway in human umbilical vein endothelial cells

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Chinese Science Bulletin 2009年第2期54卷 227-233页

作者： JANG Yu-Sung lee Eun-Ok lee Hyo-Jung lee Hyo-Jeong KIM Kwan-Hyun won Sook-Hyun lee Jae-Dong AHN Kwang Seok AHN kyoo Seok KIM Jung-Hyo YU Young-Beob KIM Sung-Hoon College of Oriental Medicine Kyunghee University 1 Hoegidong Dongdaemungu Seou1130-701 Republic of Korea Chosun Nursing College 375 Seosuk-dong Dong-gu Gwangju 501-759 Korea Department of Herbal Pharmaceutical Korea Institute of Oriental Medicine Jeonmin dong Youseonggu Daejeon 305-811 Republic of Korea

Oriental herbal medicines have been widely used for the prevention or treatment of various diseases including cancer in Asia. However, to prove their chemo preventive efficacies in modern times, scientific evidence for those herbal medicines is required. Thus, in the present study, an effective herbal cocktail Bojungbangdocktang (BJBDT) was investigated to elucidate antiangiogenic mechanism in vitro and in vivo. BJBDT significantly inhibited vascular endothelial growth factor (VEGF) induced proliferation in HUVECs at nontoxic concentrations, despite weak cytotoxicity against human umbilical vein endothelial cells (HUVECs). BJBDT also significantly suppressed VEGF-induced migration and tube formation of HUVECs. Furthermore, BJBDT treatment resulted in pale color and low hemoglobin level in Matrigel plugs, as well as dark red color and high hemoglobin level in untreated control. Interestingly, BJBDT specifically inhibited the binding of VEGF to vascular endothelial growth factor receptor 2 (VEGFR2), but not VEGFR1. In addition, friedelin, formononetin, ginsenoside Rb1, naringin, atractyloside, diosgenin, and allantonin were identified from BJBDT by high-performance liquid chromatography (HPLC) analysis as a quality of control. Taken together, these results suggest that BJBDT is a potent angiogenesis inhibitor blocking the VEGF/VEGFR2 signaling pathway in HUVECs.

关键词：血管新技术人大动脉内皮细胞 HUVECs VEGFR2

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The anti-tubercular activity of Melia azedarach L. and Lobelia chinensis Lour. and their potential as effective anti-Mycobacterium tuberculosis candidate agents

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Asian Pacific Journal of Tropical Biomedicine 2016年第10期6卷 830-835页

作者： won Hyung Choi In Ah lee Department of Biomedical Science School of Medicine Kyung Hee University Department of Medical Zoology School of Medicine Kyung Hee University Department of Chemistry College of Natural Science Kunsan National University

Objective: To evaluate the anti-mycobacterial activity of Melia azedarach L.(M. azedarach) and Lobelia chinensis Lour.(L. chinensis) extracts against the growth of Mycobacterium tuberculosis(M. tuberculosis).Methods: The anti-M. tuberculosis activity of M. azedarach and L. chinensis extracts were evaluated using different indicator methods such as resazurin microtiter assay(REMA) and mycobacteria growth indicator tube(MGIT) 960 system assay. The M. tuberculosis was incubated with various concentrations(50–800 mg/m L) of the extracts for 5 days in the REMA, and for 4 weeks in MGIT 960 system ***: M. azedarach and L. chinensis extracts showed their anti-M. tuberculosis activity by strongly inhibiting the growth of M. tuberculosis in a concentration-dependent manner in the REMA and the MGIT 960 system assay. Particularly, the methanol extract of M. azedarach and n-hexane extract of L. chinensis consistently exhibited their effects by effectively inhibiting the growth of M. tuberculosis in MGIT 960 system for 4 weeks with a single-treatment, indicating higher anti-M. tuberculosis activity than other extracts,and their minimum inhibitory concentrations were measured as 400 mg/m L and 800 mg/m L, ***: These results demonstrate that M. azedarach and L. chinensis extracts not only have unique anti-M. tuberculosis activity, but also induce the selective antiM. tuberculosis effects by consistently inhibiting or blocking the growth of M. tuberculosis through a new pharmacological action. Therefore, this study suggests the potential of them as effective candidate agents of next-generation for developing a new anti-tuberculosis drug, as well as the advantage for utilizing traditional medicinal plants as one of effective strategies against tuberculosis.

关键词： Lobelia chinensis Lour. Melia azedarach L. MGIT 960 system Drug susceptibility Tuberculosis

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