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        검색결과 166

        121.
        1999.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        New electroluminescent materials base on anthracene chromophore, [9.10-bis(α-naph -thylethenyl) anthracene (α-BNA)] were newly synthesized. The anthracene derivatives with bulky substituent possessed high melting point and they gave stable amorphous films through vacuum - sublimation methods. Three types of electroluminescent devices were fabricated with double layer and triple layer structure : ITO/TPD/emission layer/MgAg, ITO/emission layer/ OXD-7 and ITO/ TPD/ emission layer/OXD-7/MgAg, respectively. In three types of devices with the emissive layer of α-BNA, efficient orange electroluminescence was observed. In the triple layer device whit a emitting layer of 20 nm thickness , maximum luminance was about 10000 cd/ m2 at an applied voltage of 10v and maximum external quantum efficiency was 1.0%.
        4,000원
        122.
        1999.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The alkylation benzene with 1-dodecene of Mordenite, Zeolite β and Zeolite Y was studied in the stirring batch reactor. The kinds of zeolites were found to have influenced the reaction conversion and distribution of phenyldodecane isomer in the product. Compared to the alkylation conducted over Zeolite Y and Zeolite β, the alkylation over Mordenite exhibited higher distribution of 2-phenyldodecane and the alkylation conducted over Zeolite Y and Mordenite, the alkylation over Zeolite β exhibited higher distribution of heavy alkylate which formed through oligomerization reaction readily deactivated the Lewis acid sites. A special feature of the effect of the benzene to 1-dodecene ratio the reaction conversion and selectivity of phenyldodecane isomer was found. At alkylation of benzene with 1-dodecene over Zeolite β, when the catalyst content in the system was high, the reaction will reach the optimal conversion at the higher B/D. When the benzene to 1-dodecene ratio was high, the selectivity of phenyldodecane isomer is high. It was also found that at the similar reaction conversion there was the same product distribution regardless of D/C ratio.
        4,000원
        124.
        1995.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A study has been performed on the cockroach knowledge and perception of managers, employees and consumers, and the cockroach control management in food service institutions. A total of 759 subjects including 101 managers, 293 employees and 365 consumers was surveyed in Seoul and Pusan areas from July 1994 to September 1994. The results obtained are as follows: The mean rates of the cockroach knowledge (i.e. 62.26/100.0) and perception (i.e. 23.67/30.0) of the consumers were significantly (p<0.001) lower than those of the managers (i.e. 68.87/100.0 and 25.30/30.0, respectively) and the employees (i.e. 69.09/100.0 and 26.99/30.0, respectively). In the cockroach detection rates, however, much higher rate was seen in the consumer group (i.e. 79.5%) than the manager (i.e. 43.3%) and the employee (i.e. 48.5%) groups. Forty and seventy percents of the subjects have suffered from allergies and nuisance by cockroaches, respectively. The cockroach control was performed by 75.5% of the food service institutions and 70.8% of them contracted with pest control operators to reduce the cockroach populations. The cockroach control methods of the operators were aerosol (40.7%) and insecticidal baits (30.5%). Only 33.7% of the institutions had the budgets for the cockroach control. For public health, the managers and the employees of the institutions need to be educated about cockroaches and hygiene. Also, it is suggested that cockroaches be regularly controlled by professional pest control operators.
        4,300원
        127.
        2019.04 서비스 종료(열람 제한)
        In this study, the tendency of flow characteristics according to the mixing design of mortar and mortar standard reference materials was analyzed based on the constituents of the standard reference materials for mortar. As a result, the plastic viscosity of the mortar tends to be maintained according to the amount of fine aggregate, while the yield value tends to increase greatly. On the other hand, in the case of the standard reference materials for mortar, the plastic viscosity tends to increase largely according to the amount of fine aggregate substitutes, while the yield value tends to be almost maintained.
        128.
        2017.04 서비스 종료(열람 제한)
        The purpose of this study is to understand the rheological characteristics analysis method for the development of reference materials for cement paste considering the required performance of standard materials including particles
        129.
        2017.04 서비스 종료(열람 제한)
        The mechanical properties were evaluated to examine the optimum adding amount of AC and UT viscosity agent by mixing two viscosity agent according to the adding ratio. When the ratio of AC and UT viscosity agent was 5:5, It was most suited for high-fluidity concrete with low binders by increasing workability and effect of reducing viscosity.
        130.
        2017.04 서비스 종료(열람 제한)
        In recent years, in order to reduce self-weight of structural elements, the use of SCP(Steel Concrete Plate) is getting increased. Since SCP has complicated sectional shape and includes large amount of studs, the use of shrinkage reduction concrete is required. Therefore, in this study, to prevent the restrained shrinkage behavior by stud, the effects of using expansive agent (EA) and shrinkage reducing agent (SRA) was investigated.
        131.
        2017.04 서비스 종료(열람 제한)
        The goal of this study is to investigate the effectiveness of the use of multiple materials in plate-like structures structure and provide engineers and designers an appropriate view point of multi-material topology optimization when making decision and information in design. Element density distribution contours of mixing multiple material densities are linked to Solid Isotropic Material with Penalization (SIMP) as a design model. The mathematical formulation of multi-material topology optimization problem solving minimum structural compliance is an alternating active-phase algorithm with the Gauss-Seidel version as an optimization model of optimality criteria. Some numerical examples are considered to illustrate the reliability and accuracy of the present design method for multi-material topology optimization.
        132.
        2017.04 서비스 종료(열람 제한)
        This paper studies about the buckling analysis of multi-material structure especially compressed column using topology optimization. The buckling is stated as a constraint in the optimization problem. A clamped-pinned column with applied axial compressive load is analyzed. An active-phase algorithm is used to solve multi-phase topology optimization problem. The distribution of different materials is determined in a isotropic two-dimensional design domain. The material properties is modified based on the Solid Isotropic Material with Penalization (SIMP) interpolation approach. The Method of Moving Asymptotes (MMA) is used to update the topology design variables which is relative element densities. The optimal designs of the column structure are presented and discused in the numerical applications.
        133.
        2017.01 KCI 등재 서비스 종료(열람 제한)
        The purpose of this study is to understand the rheological characteristics analysis method for the development of reference materials for cement paste considering the required performance of standard materials including particles.
        134.
        2017.01 KCI 등재 서비스 종료(열람 제한)
        The mechanical properties were evaluated to examine the optimum adding amount of AC and UT viscosity agent by mixing two viscosity agent according to the adding ratio. When the ratio of AC and UT viscosity agent was 5:5, It was most suited for high-fluidity concrete with low binders by increasing workability and effect of reducing viscosity.
        135.
        2017.01 KCI 등재 서비스 종료(열람 제한)
        In recent years, in order to reduce self-weight of structural elements, the use of SCP(Steel Concrete Plate) is getting increased. Since SCP has complicated sectional shape and includes large amount of studs, the use of shrinkage reduction concrete is required. Therefore, in this study, to prevent the restrained shrinkage behavior by stud, the effects of using expansive agent (EA) and shrinkage reducing agent (SRA) was investigated.
        136.
        2016.06 KCI 등재 서비스 종료(열람 제한)
        In this study, global climate change scenario by Hadley Centre Global Environmental Model version 2-Atmosphere and Ocean (HadGEM2-AO) is dynamically downscaled using four regional climate models (RCMs). All RCMs with 12.5-km and 50-km resolution are integrated for continuous 27 years (1979-2005). In general, RCMs with higher horizontal resolution more reasonably capture the spatial distribution of precipitation over South Korea compared to those with lower resolution. In particular, heavy precipitation regions related to complex mountain ranges are well simulated due to detailed topography in RCMs with higher resolution. Difference between RCMs with dissimilar resolutions is relatively robust in summer compared to other seasons. This could be associated with that higher resolution and detailed topography lead to more realistic simulation of heavy summer precipitation related to mesoscale phenomena.
        137.
        2016.04 서비스 종료(열람 제한)
        The goal of this study is to investigate the effectiveness of the use of multi constructional material in unit module plate of steel grid structure and provide engineers and designers an appropriate view point of multi-material topology optimization when making decision and information in design. The material distribution is implemented with the use of 3 materials in a given plate under prescribed loading and boundary conditions. Topology changes through automatic distribution of multi materials are presented during optimization procedures showing that there could be selective structural design possibility when using multi materials. The cross sections, stiffness and cost of material combination are useful information for engineers and designers in making design decision.
        138.
        2015.12 KCI 등재 서비스 종료(열람 제한)
        This study investigated the future change in surface wind over the Korean Peninsula using a high-resolution climate change scenario projected by a regional climate model (RCM). In the evaluation of historical runs (1981-2010), the RCM reasonably reproduced a 30-year annual mean surface wind and it also represented climatological seasonal wind pattern properly. To examine the future change in surface wind, the results from RCP8.5 run for 30 years (2071-2100) were compared with those from historical run. Despite of slight differences among seasons, southerly differences were overall dominant. This indicated that southerly prevailing wind for summer was intensified in the future climate, while northerly prevailing wind for other seasons was reduced. The changes in the seasonal mean surface wind were significantly associated with those in the surface pressure distribution surrounding the Korean Peninsula. In the future climate, the monthly mean wind speed was reduced compared in the present climate. However, the magnitude and annual variability of the annual maximum wind speed tended to increase in the future climate.
        139.
        2015.10 서비스 종료(열람 제한)
        In this study, viscosity was minimized for production of viscosity-agent type high fluidity concrete with normal strength, and segregation resistance was maximized with viscosity agent and use of superplasticizer. Their applicability and physical property were examined.
        140.
        2015.10 서비스 종료(열람 제한)
        The goal of this study is to evaluate the effectiveness of using more than one material for unit element flange of Archigird. The flange is optimized using the solution of multi-material topology optimization. In this topic, multi-material minimum structural compliance topology optimization problems is solved basedon the classical optimality criteria method. Three different types of steel material are used: SS400, SM570, UL700. The distribution of these three materials is considered by changing the participating volume of materials in the given shape. Material distribution is implemented with the use of 2 materials and 3 materials. The strain energy and the price of three steel types are used for comparison.
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