• Journal of Energy Engineering
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• v.2 no.3
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• pp.268-275
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• 1993

A series of parametric investigations are performed in order to resolve the flow characteristic of a Quebec city stoker incinerator. The parameters considered in this study are five internal configurations of the Quebec city stoker itself and its modified ones, primary air velocity, the injection velocity and angle of the secondary air, and the reduction of the stoker exit area. A control-volume based finite-difference method by Patankar together with the power-law scheme is employed for discretization. The resolution of the pressure-velocity coupling is made by the use of SIMPLEC algorithm. The standard, two equation, k-$\varepsilon$ model is incorporated for the closure of turbulence. The size of recirculation region, turbulent viscosity, the mass fraction of the secondary air and pressure drop are calculated in order to analyze the characteristics of flow field. The results are physically acceptable and discussed in detail. The flow field of the Quebec city stoker shows the strong recirculation zone together with the high turbulence intensity over the upper part of the incinerator.

• Journal of the Korean Society for information Management
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• v.34 no.3
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• pp.67-87
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• 2017

This study aims to investigate the effects of college students' library satisfaction on college life satisfaction. In order to test this relationship, two surveys were conducted involving 360 college students at two universities in Seoul. The results of the first survey show that after controlling for the educational service satisfaction and facilities satisfaction, there is a significant influence of college students' library satisfaction on college life satisfaction. The second study added variables for the three components of library service quality (librarian service quality, library resources and service quality, and library facilities and environmental quality). The results of the second survey show that there is a significant influence of library service quality on college library satisfaction, and again a significant influence of college students' library satisfaction on college life satisfaction. Moreover, the results of two group analysis show that the influence of college library satisfaction on college life satisfaction is stronger in high usage group than low usage group. The theoretical and practical implications of this study are discussed.

• Journal of Educational Research in Mathematics
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• v.17 no.3
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• pp.253-270
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• 2007

by A.C. Clairaut was written based on the historico-genetic principle such as his . In this paper, by analyzing his we can induce six principles that Clairaut adopted to teach algebra: necessity and curiosity as a motive of studying algebra, harmony of discovery and proof, complementarity of generalization and specialization, connection of knowledge to be learned with already known facts, semantic approaches to procedural knowledge of mathematics, reversible approach. These can be considered as strategies for teaching algebra accorded with beginner's mind. Some of them correspond with characteristics of , but the others are unique in the domain of algebra. And by comparing Clairaut's approaches with school algebra, we discuss about some mathematical subjects: setting equations in relation to problem situations, operations and signs of letters, rule of signs in multiplication, solving quadratic equations, and general relationship between roots and coefficients of equations.

• The Journal of the Korea Contents Association
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• v.14 no.2
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• pp.294-307
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• 2014

The purpose of this study is to examine the trajectory of early adolescent aggression and to assess the effects of perceived family factors on it. This study investigated the changes in aggression over time and the effects of three family factors, parental attachment, parental monitoring, and family conflict, on the changes using multilevel modeling. The data from Korea Youth Panel Survey(KYPS) of fourth graders who were followed over five years were analyzed. The results indicated that there was a significant average increase followed by a slight decrease in aggression over time; that is, the data followed a quadratic trend. Parental attachment, parental monitoring, and family conflict had significant time-independent effects on aggression, while only family conflict had a significant time-dependent effect on aggression. These results imply that family factors need to be emphasized in planning prevention and intervention programs to reduce aggression during adolescence.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2777-2784
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• 2011

In this paper, DOA(direction of arrival) of multiple incident signals received from linear array antenna and circular array antenna, which is based on nonparametric estimation algorithm, and adaptive beam-forming algorithm are studied and analyzed. In nonparametric estimation algorithm, we minimize a regularized objective function for finding a estimate of the signal energy as a function of angle, using nonquadratic norm which leads to supper resolution and noise suppression. And then, DOA is estimated by the signal and noise spatial steering vector, and adaptive beam-forming pattern is improved by weight vectors obtained from the spatial vector. Especially, the discrimination ability of DOA and the adaptive beam-forming ability according to antenna array methods and the number of array elements are compared and considered.

• The Journal of the Korea Contents Association
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• v.15 no.4
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• pp.65-74
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• 2015

This study is dealing with sound of Hitchcock's movie <The Man Who Knew Too Much (1956)> from Peirce's semiotic perspective. This paper examined Peirce's theory prior to semiotic discussion, and analyzed the three elements of sound(speech, noise, music) depending on the type of sign that he presented. Music is possible to express emotions as an index through intervals. The instrument sound under firstness works as the element of narrative and it may be a dynamic object, transferred to the dicisign of secondness. Also, a word in speech is possible to represent an object allusively through an icon in the film. Noise and music as an index are serving to increase the tension of film. Meanwhile, two different genres of music on the juxtaposition are in charge of narrative function as a dicisign. Thus, Hitchcock's sound has various semiotic qualities of signification depending on the context.

• Journal of the Mineralogical Society of Korea
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• v.17 no.1
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• pp.23-35
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• 2004

The weathering characteristics of periodically submerged sedimentary rocks in the Sayeon dam, Ulsan was examined by field work, electron probe micro-analysis, X-ray diffraction, and X-ray fluorescence spectrometry. Analysis of fracture zone and exfoliation showed the submerged sedimentary rocks have undergone severe mechanical weathering. Mechanical weathering in the water-rock interface accelerated chemical weathering, such as dissolution and alteration of the most of minerals except for quartz in the weathering zone. The dissolution of carbonates specially calcite, is remarkable creating the cavities, whereas formation of minerals including clay minerals is not active. The sedimentary rocks have been periodically submerged for a certain period of time, and have repeated freezing and thawing. This mechanical weathering favored infiltration, which accelerated mineral dissolution. The high content of easily soluble carbonate of the sedimentary rocks is likely the major cause of intense chemical weathering. The dissolved elements within the infiltrated water interrupted the occurrence of clay and weathering minerals, and expend fractures by infiltrated water accelerated weathering process.

• Korean Journal of Microbiology
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• v.48 no.2
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• pp.87-92
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• 2012

The purpose of this study was to examine the cellular response of Salmonella typhimurium exposed to tea polyphenols (TPP) extracted from Korean green tea (Camellia sinensis L.). TPP showed a dose-dependent bactericidal effect on S. typhimurium. Analysis of cell membrane fatty acids of S. typhimurium cultures treated with TPP identified unique changes in saturated and unsaturated fatty acids, while scanning electron microscopic analysis demonstrated the presence of perforations and irregular rod forms with wrinkled surfaces in cells treated with TPP. Two-dimensional polyacrylamide gel electrophoresis of soluble protein fractions from S. typhimurium cultures showed 16 protein spots increased by TPP. These up-regulated proteins including proteins involved in antioxidants and chaperons, transcript and binding proteins, energy and DNA metabolism were identified by peptide mass fingerprinting using MALDI-TOF. These results provide clues for understanding the mechanism of TPP induced stress and cytotoxicity on S. typhimurium.

• Korean Journal of Crystallography
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• v.5 no.1
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• pp.24-32
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• 1994

The study of (0001), (1120) and (1011) GAN epitaxy films grown on the (0001),(1012) and (1120) α-Al2O3 substrates have been investigated using the haliar vapor phaes epitaxy(HVPE) method in Ga/HCI/NH3/He system. XRD, RHEED and SEM are used for the study of the films struction and surface morphology. Chemical composition of the film surface is estimsted by XPS. The following orientation relationships are observed; (0001) GaN /(0001) Al2O3 (1120) GaN/ (1012) Al2O3 and (0001) and (1011) GaN/ (1120) Al2O3 in accordance with growth conditions. The (0001) GaN films grown on(0001) and (1120) a-Al2O3 substrates at higer temperature(1050℃) have shown two dimensional grownth mechanism. Form SEM and RHEED, the smoother surface morphology and better structure are observed for the (1011) GaN films grown on (1120) sapphire at higer temperature.

• Journal of the Korean earth science society
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• v.36 no.6
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• pp.543-552
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• 2015

This study examines the processes of rock weathering and tafoni formation targeting tafoni at Mt. Cheonsaeng, Gumi-si, Gyeongsangbuk-do. In the study area, a frequency of tafoni is high in conglomerate and conglomeratic sandstone among regional sedimentary rocks, which means that an initial stage of the formation begins a breakaway of gravel from bedrock and also exfoliation from rock surface. Geomorphologically tafoni have intensively been developed at the southfacing slope with exposed rocks, which means that its formation was favorably controlled by environmental conditions including strong influences of mechanical weathering in winter and chemical weathering in summer times. The results of measuring water content at a tafoni-bearing rock surface using GIS interpolation analysis indicate that moisture rate in/around tafoni is higher than the periphery. Thus, it is considered that moisture distribution at a rock surface plays a role in its formation. Analysis of percipitation and secondary minerals induced by chemical weathering is in progress.