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        검색결과 6

        1.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study manufactured a CIG-based composite coating layer utilizing a new warm spray process, and amixed powder of Cu-20at.%Ga and Cu-20at.%In. In order to obtain the mixed powder with desired composition, theCu-20at.%Ga and Cu-20at.%In powders were mixed with a 7:1 ratio. The mixed powder had an average particle size of35.4 µm. Through the utilization of a warm spray process, a CIG-based composite coating layer of 180 µm thicknesscould be manufactured on a pure Al matrix. To analyze the microstructure and phase, the warm sprayed coating layerunderwent XRD, SEM/EDS and EMPA analyses. In addition, to improve the physical properties of the coating layer, anannealing heat treatment was conducted at temperatures of 200℃, 400℃ and 600℃ for 1 hour each. The microstructureanalysis identified α-Cu, Cu4In and Cu3Ga phases in the early mixed powder, while Cu4In disappeared, and additionalCu9In4 and Cu9Ga4 phases were identified in the warm sprayed coating layer. Porosity after annealing heat treatmentreduced from 0.75% (warm sprayed coating layer) to 0.6% (after 600℃/1 hr. heat treatment), and hardness reducedfrom 288 Hv to 190 Hv. No significant phase changes were found after annealing heat treatment.
        4,000원
        2.
        2005.06 KCI 등재 서비스 종료(열람 제한)
        울릉분지 남부 대륙붕 석유탐사 시추공에서 회수된 사암 내에서 산출되는 녹니석-스멕타이트 혼합층 점토광물에 대하여 광물학적 및 화학적 연구를 수행하였다. X-선 회절분석과 화학분석 결과에 의하면 이 점토광물은 녹니석과 스멕타이트가 1:1 비율로 구성된 이팔면체형의 녹니석-스멕타이트 혼합층광물, 즉 토수다이트이다. 이 토수다이트는 Li가 풍부한 토수다이트로서 열수변질대에서 보고되는 토수다이트와 거의 동일하다. 이것은 토수다이트가 산출되는 지역은 열수변질과 관련된 열적 영향을 받았음을 지시한다. 실제로 이 시추공이 있는 지역은 단층과 습곡이 많이 발달되어 있고 구조적으로 변형되어 있다. 이와 같은 점을 고려할 때 하부로부터 열수가 올라와서 사암 내의 토수다이트의 생성에 기여했을 것으로 생각된다.
        3.
        1998.10 KCI 등재 서비스 종료(열람 제한)
        A Jump model was evaluated for the calculation of hourly mixing height and mean potential temperature within the height. The Jump model was modified for estimation of downward heat fluxes by mechanical convections and surface heat fluxes. The surface heat fluxes were estimated from routine weather data such as solar radiation and air temperature. Total of 8 upper-air data observed at 0000UTC and 0600UTC in Osan station during April 23 to 26, 1996 were analyzed, and compared to the model results in detail. The calculated mixing heights and potential temperatures within the height were comparable to the observations, but some differences were showed. The calculated mixing heights were generally higher than observations. And, when variations of wind directions were large, the large difference of potential temperature was occurred. From the results, it was important to note that vertical motions and advections of air masses would affect to the growth of the mixing height.
        4.
        1997.12 KCI 등재 서비스 종료(열람 제한)
        Based on the method of determination for relative stability of each phase from the difference among the interaction parameters of the phases consisting the mixed layer, the types of interactions between layers were specified and interaction parameter between layers in ordered domain was analytically derived as a function parameter between layers in ordered domain was analytically derived as a function of not only temperature and mole fraction of layers but also ordering parameter. Interaction parameter between the different layers in ordered phase, L is as follows:{{{{ {L }_{1 } (X,Q,T)= { C} over { Q} -4(1-2Q) { L}^{2 } - { RT} over {2} ln { 1} over {2 } - { 2RT} over { { X}_{ s} } ln { { 4QX}`_{s } ^{2 } } over {(1- { X}_{s }- { QX}_{s })( { X}_{s }- {QX }_{s } ) } }}}}L2 is the interaction parameter between ordered and disordered phase in domain and is the mole fraction of the domain which represent the infinite length of mixed layer mineral and Q and C are the reaction progress parameter and arbitrary constant, respectively. This equation was used for the I/S mixed layer clay minerals to infer the relative stability of R1 type I/S mixed layer in the temperature range from 373K to 450K. The result of calculation suggest that, owing to the decrease in interaction parameter with increasing temperature. The interaction parameter decreases more rapidly with decreasing mole fraction of smectite in domain, which is consistent with the fact that the probability of finding the series smectite layer is lo in the domain with small mole fraction of smectite layers in natural system.
        5.
        1997.10 KCI 등재 서비스 종료(열람 제한)
        One-dimensional thermodynamic mixed layer model to simulate variations of meteorological variables within the planetary boundary layer has been developed in this study. This model consists of 2 prognostic equations, which can predict the variations of potential temperature and mixing ratio and several diagnostic equations. Physics within the surface and mixed layers has been considered seperately in the model. For the variations of the model, its result has been analysed and compared with observated data over the Dukyang Bay for one day, July 23, 1992. The simulated height of mixed layer is comparable to the observation and the variations of temperature and mixing ratio in the mixed layer are also reasonably simulated. Those imply that the model responds appropriately with given boundary conditions in spite of its simplified assumptions applied to the model and insufficient boundary and initial conditions.
        6.
        1993.03 KCI 등재 서비스 종료(열람 제한)
        The layer that is directly influenced by ground surface is called the atmospheric boundary layer in comparison with the free atmosphere of higher layer. In the boundary layer, the changes of wind, temperature and coefficient of turbulent diffusion in altitude are large and have great influences an atmospheric diffusion. The purpose of this paper is to express the structure and characteristics of development of mixed layer by using laboratory experiment and numerical simulation. Laboratory experiment using water tank are performed that closely simulate the process of break up of nocturnal surface inversion above heated surface and its phenomena are analyzed by the use of horizontally averaged temperature which is observed. The result obtained from the laboratory experiment is compared with theoretical ones from k-ε numerical model. The results are summarized as follows. 1) The horizontally averaged temperature was found to vary smoothly with height and the mixed layer developed obviously being affected by the convection. 2) The mean height of mixed layer may be predicted as a function of time, knowing the mean initial temperature gradient. The experimental values are associated well with the theoretical values computed for value of the universal constant C_T=0.16, our C_T value is little smaller than the value found by Townsend and Deardorff et al.