• Korean Journal of Hydrosciences
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• v.4
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• pp.81-92
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• 1993

This paper presents a model on the migration characteristics which is developed by using the equations for conservation of mass, momentum, and for lateral stability of the streambed. This model enables prediction of the magnitude the location of near-bank bed scour as well as rates and direction of meander migration in the sine-wave type revers (SWR) of small sinuosity. It is evident from this study that the transverse bed slope factor B' and transverse mass flux factor play significant roles in predicting migration characteristics, and their values of B'=4.0 and $\alpha$= 0.4 seem reasonable. This model will produce a useful quidelines in planning, design, construction, and development of SWR basin projects.

• Bulletin of the Korean Mathematical Society
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• v.53 no.1
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• pp.227-245
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• 2016

A generalized constant ratio surface (GCR surface) is defined by the property that the tangential component of the position vector is a principal direction at each point on the surface, see [8] for details. In this paper, by solving some differential equations, a complete classification of Lorentz GCR surfaces in the three-dimensional Minkowski space is presented. Moreover, it turns out that a flat Lorentz GCR surface is an open part of a cylinder, apart from a plane and a CMC Lorentz GCR surface is a surface of revolution.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.193-200
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• 2003

This paper proposes a novel algorithm to recognize the curve of a structured road. The proposed algorithm uses an LCF (Lane Curve Function) obtained by the transformation of a parabolic function defined on world coordinate into image coordinate. Unlike other existing methods, the algorithm needs no transformation between world coordinate and image coordinate owing to the LCF. In order to search for an LCF describing the lane best, the differential comparison between the slope of an assumed LCF and the phase angle of edge pixels in the LROI (Lane Region Of Interest) constructed by the LCF is implemented. As finding the true LCF, the lane curve is determined. The proposed method is proved to be efficient through various kinds of images, providing the reliable curve direction and the valid curvature compared to the real road.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.208-213
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• 2008

Since The measured solar radiation incident on tilted surfaces by all directions has been widely used as important solar radiation data in installing solar flat-plate collectors. To maximize the incident beam radiation, the slope, which is the angle between the plane of the surface in question and the horizontal, and the solar azimuth angles are needed for these solar thermal systems. This is because the performance of the solar thermal system is much affected by angle and direction of incident rays. Recognizing those factors mentioned above are of importance, actual experiment has been performed in this research to obtain the angle of inclination with which the maximum incident rays can be absorbed. The results obtained in this research could be used in installing optimal solar flat-plate collectors.

• Water for future
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• v.26 no.1
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• pp.103-114
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• 1993

Migration characteristics with forms of channels and bed conditions are studied by constant-radius curve (CRC), sine-generated curve (SGC) and small-wave theory (SWT) method. For channels which are meandering and of which bed conditions are of coarse materials, transverse bed slope, depth and velocity distributions are predicted by CRC and SGC method, and the results are compared with measured field data, And for fine bed-materials of the sinuous channels, lateral and downvalley migration rates are computed by SWT method. It is confirmed from this investigation that transverse mass-flux factor plays significant roles in determining of magnitude and direction of meander migration.

• Transactions of Materials Processing
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• v.10 no.3
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• pp.179-184
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• 2001

The influence of the fatigue crack propagation by shot peening was studied in this paper. Fatigue tests were carried out on the unpeened and shot peened CT specimens. The changes of mechanical properties, residual stress, fatigue fracture surface etc. by shot peening were investigated. The mechanical properties, residual stress, fatigue surface etc. by shot peening were investigated. The mechanical peened specimen improved in fatigue life up to 14% by shot peening. The reason of increase in the fatigue life was closely related with the compressive residual stress, which was 519.7MPa on surface. Another reason was the constraint on crack opening on surface region, it is due to the decrease in slope of crack propagation direction.

• International Journal of Fluid Machinery and Systems
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• v.4 no.2
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• pp.235-242
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• 2011

An application of contra-rotating rotors, in which a rear rotor is in tandem with a front one and these rotors rotate in the opposite direction each other, has been proposed against a demand for developing higher specific speed axial flow pump. One prototype rotors, which we have designed with a conventional method, has given the positive slope of head characteristic curve especially in the rear rotor. It is necessary to understand the internal flow behavior in the rear rotor to establish the design guideline for achieving higher and more reliable performance. In the present study, we carried out the experimental investigations of the internal flow field of the rear rotor, especially at the partial flow rate, by Laser Doppler Velocimetry (LDV) for the main flow and the limiting streamlines observation on rotor surfaces for the boundary layer flows.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1146-1149
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• 2006

In this study, nanocomposite layer composed of PMMA-co-MMA and $TiO_2$ was prepared by sol-gel process using TTIP as a precursor and was utilized as a gate insulator of OTFTs. The composite insulator provides the lower threshold voltage and the enhanced sub threshold slope of OTFTs mainly due to its higher dielectric constant than that of the bare PMMA-co-MMA. Consequently, it is demonstrated that the sol-gel process can open an interesting direction for the fabrication of high-performance OTFTs, and contribute for OTFTs to be feasible for real applications.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.60-65
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• 2003

A new algorithm was developed to interpret joint orientations from a pair of images of the rock slope to overcome the limitation of photographing direction as in the parallel stereophotogrammetric system and to maximize the range of image measurement. This algorithm can be regarded as a modified multistage convergent photographing system. To determine camera parameters in the perspective projection equation that are the major elements in the photogrammetric technique, a new concept was developed by using three ground control points and single ground guide point. This method could be considered to be very simple when compared with other existing methods which use a number of ground control points and complicated analysis processes.

• Journal of Environmental Science International
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• v.12 no.1
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• pp.15-22
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• 2003

Fifteen major naturally populated habitats around the Mt. Halla, Jeju province for wild Cornus kousa are mostly located on the southeast side of the mountains at 850-1,550m in altitude at sea level and are in half sunney areas. More than 40.0% of the naturally populated area of Cornus kousa are edge of forest areas and 53.3% populate on the steep slope of the mountain in 0-5℃. The direction of the slop for about 40.0% of total populated areas is southeast. In the naturally populated areas, total of 64 taxa dividing into 42 families, 59 genera 56 species and 8 varieties have been shown, mostly Hydrangea petiolaris, Rubus oldhamii, Ilex crenata, Sasa quelpaertensis, Ligustrum obtusifolium. It is suggested that these areas are secondary forest in a typical deciduous forest in Mt. Halla where the second transition had been progressed after forest damage or environmental stress. The index of species diversity of plant groups in these areas is 1.286-4.238 based on the Shannon-Wiener's method.