• 한국해양학회지
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• v.20 no.1
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• pp.43-49
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• 1985

The Changgu Bay, a macrotidal coastal embayment of the west coast of Korea, is an area of extensive intertidal sedimentation. Three types of major sediment facies are identified based on grain size analysis: silt, sandy-silt, and silty-sand facies. It is found that intertidal sediment facies comprise a continuum of progressively finer sediments from lower flat to upper one. The X-radiography of the cores in the intertidal zone show a wide variety of physical and biogenic sedimentary structures. The major structures include bioturbation, current ripple and parallel-laminae. Bioturbations are observed in all core samples, especially in the silt flat zone. The degree of bioturbation increases laterally from sandy facies (low tide level) to silt facies (high tide level) due to favorable properties of fine mud for organisms. The ripple laminae, composed of current ripple foresets, characterize the silty-sand and sandy-silt flats. The parallel laminae are extensively bioturbated, and two types of laminae are distinguishable; thick-laminae with a thickness of 1 to 5mm and thin-laminae with a thickness of less than 1mm.

• Communications of the Korean Mathematical Society
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• v.14 no.2
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• pp.385-392
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• 1999

We deal with a differential equation which is constructed from homogeneous function, and its geometrical meaning in a Finsler space. Moreover, were prove that a locally Minkowski space satisfying a differential equation F\ulcorner=0 is flat-parallel.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.248-256
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• 2005

This paper presents the design method of the DC/DC converter using flat transformer which is suitable for midium or large capacity and high density power supply. Flat transformer module is composed and manufactured of multi-transformers in parallel and has a number of parallel single turn secondary windings. Therefore, its leakage inductance is highly decreased and it is more suitable for high frequency operation than conventional one. In this paper, we manufactured and tested 750W AC/DC converter with variable output powers to verify the performance of the flat transformer.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.589-593
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• 2016

Microbial fuel cell (MFC) can produce electricity from oxidation-reduction of organic and inorganic matters by electrochemically active bacteria as catalyst. Stacked MFCs have been investigated for overcoming low electricity generation of single MFC. In this study, two-typed stacked-MFCs (submerged-flat and stand-falt) were operated according to electrode connection for optimal stacked technology of MFC. In case of submerged-flat MFC with all separator electrode assembly (SEA) sharing anode chamber, MFC with mixed-connection showed more voltage loss than MFC with single-connection method. And MFC stacked in parallel showed better voltage production than MFC stacked in series. In case of stand-flat MFC, voltage loss was bigger when SEAs sharing anodic chamber only were connected in series. Voltage loss was decreased when SEAs parallel connected SEAs sharing anodic chamber were connected in series.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.1
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• pp.55-65
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• 2006

The air and water flow distribution are experimentally studied for a round header - flat tube geometry simulating a parallel flow heat exchanger. The number of branch flat tube is thirty. The effects of tube outlet direction, tube protrusion depth as well as mass flux, and quality are investigated. The flow at the header inlet is identified as annular. For the downward flow configuration, the water flow distribution is significantly affected by the tube protrusion depth. For flush-mounted configuration, most of the water flows through frontal part of the header. As the protrusion depth increases, more water is forced to the rear part of the header. The effect of mass flux or quality is qualitatively the same as that of the protrusion depth. Increase of the mass flux or quality forces the water to rear part of the header. For the upward flow configuration, however, most of the water flows through rear part of the header. The protrusion depth, mass flux, or quality does not significantly alter the flow pattern. Possible explanations are provided based on the flow visualization results. Negligible difference on the water flow distribution was observed between the parallel and the reverse flow configuration.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.4
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• pp.369-375
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• 2008

The kinematics and control problem of a visual alignment system is investigated, which plays a crucial role in the fabrication process of flat panel displays. The first solution is the inverse kinematics of a 4PPR parallel alignment mechanism. It determines the driving distance of each joint to compensate the misalignment between mask and panel. Second, an efficient vision algorithm for fast alignment mark recognition is suggested, where by extracting essential feature points to represent the geometry of a mark, the geometric template matching enables much faster object recognition comparing with the general template matching. Finally, the overall visual alignment process including the kinematic solution, vision algorithm, and joint control is implemented and experimental results are given.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.4
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• pp.130-136
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• 2008

The refrigerant R-134a flow distributions are experimentally studied for a round header/ten flat tube test section simulating a brazed aluminum heat exchanger. Three different inlet orientations(parallel, normal, vertical) were investigated. Tests were conducted with downward flow for the mass flux from 70 to 130 $kg/m^2s$ and quality from 0.2 to 0.6. In the test section, tubes were flush-mounted with no protrusion into the header. It is shown that normal and vertical inlet yielded approximately similar flow distribution. At high mass fluxes or high qualities, however, slightly better results were obtained for normal inlet configuration. The flow distribution was worst for the parallel inlet configuration. Possible explanation is provided based on flow visualization results.

• Bulletin of the Korean Mathematical Society
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• v.41 no.4
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• pp.609-618
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• 2004

Pseudo-parallel real hypersurfaces in complex space forms can be defined as an extrinsic analogues of pseudo-symmetric real hypersurfaces, that generalize the notion of semi-symmetric real hypersurface. In this paper a classification of the pseudo-parallel real hypersurfaces in a non-flat complex space forms is obtained.

• Bulletin of the Korean Mathematical Society
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• v.40 no.4
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• pp.649-661
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• 2003

The ($\alpha,\;\beta$)-metric is a Finsler metric which is constructed from a Riemannian metric $\alpha$ and a differential 1-form $\beta$. In this paper, we discuss the projective flatness of Finsler spaces with certain ($\alpha,\;\beta$)-metrics ([5]) in a locally Minkowski space.

• Bulletin of the Korean Mathematical Society
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• v.55 no.1
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• pp.227-237
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• 2018

In this paper, we study some geometric structures of a weakly cyclic Z-symmetric manifold (briefly, $[W CZS]_n$). More precisely, we prove that a conformally flat $[W CZS]_n$ satisfying certain conditions is special conformally flat and hence the manifold can be isometrically immersed in an Euclidean manifold $E^n+1$ as a hypersurface if the manifold is simply connected. Also we show that there exists a $[W CZS]_4$ with one parameter family of its associated 1-forms.