• Magazine of the Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.35-38
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• 2010

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.115-116
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• 2005

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.4
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• pp.282-285
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• 2002

The magnitude of evanescent modes in terms of dynamics is investigated in case that the transformation of water waves is predicted using the linear wave theory. In other words, derivation is made of both the kinetic and potential wave energies of evanescent modes as welt as propagating modes. The evanescent modes consist of compound components of propagating and evanescent modes, those of identically equal evanescent modes, and those of identically different evanescent modes. The wave energy per a horizontal distance decreases exponentially with the distance.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.202-204
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• 2009

Erosion is a common failure mode of materials frequently encountered in plant and power industry. Although the erosion resistance of Fe-base alloy has been inferior to the other expensive materials, it is expected that the strain-induced martensitic transformation can impart high erosion resistance to Fe-base alloy. The key technology to develop Fe-base metal cored welding wire for erosion resistant overlay welding may include the strain-induced metallurgy for hardening rate control and the welding flux metallurgy for dilution control. Sophisticated studies showed that the strain-induced martensitic transformation behavior was related to the critical strain energy which was dependent on the alloy composition. Dilution and bead shape of overlay weld were proved to be affected by metal transfer mode during gas tungsten arc welding and elements in welding fluxes. It was considered that the highly erosion resistant Fe-base overlay weld could be achieved by precise control of alloy composition to have proper level of critical strain energy for energy absorption and welding flux formulation to have small amount of deoxidizing metallic elements for dilution.

• Korean Journal of Materials Research
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• v.25 no.8
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• pp.417-422
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• 2015

In this study, low-carbon hypoeutectoid steels with different ferrite-pearlite microstructures were fabricated by varying transformation temperature. The microstructural factors such as pearlite fraction and interlamellar spacing, and cementite thickness were quantitatively measured and then Charpy impact tests conducted on the specimens in order to investigate the correlation of the microstructural factors with impact toughness and ductile-brittle transition temperature. The microstructural analysis results showed that the pearlite interlamellar spacing and cementite thickness decreases while the pearlite fraction increases as the transformation temperature decreases. Although the specimens with higher pearlite fractions have low absorbed energy, on the other hand, the absorbed energy is higher in room temperature than in low temperature. The upper-shelf energy slightly increases with decreasing the pearlite interlamellar spacing. However, the ductile-brittle transition temperature is hardly affected by the pearlite interlamellar spacing because there is an optimum interlamellar spacing dependent on lamellar ferrite and cementite thickness and because the increase in pearlite fraction and the decrease in interlamellar spacing with decreasing transformation temperature have a contradictory role on absorbed energy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.474-479
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• 2016

As the Eco-energy is recently required, electrical energy is fast increased. Several induction heating methods are attractive for Eco-energy and energy saving. In this paper, electrical fan heater was designed and developed with new concept for energy saving by electromagnetic induction heating. Proposed system was composed of three module, blast part, induction heating part and power transformation part. Induction heating method was adapted for heating and the resonant inverter was used for increasing of the power transformation efficiency. Full-bridge resonant inverter was adopted to resonant inverter. This system was composed of induction heating part made with metal(SUS 40 series), and power transformation part made with rectifier module, filter module and resonant inverter. From these results, the proposed new electric heater could be saved the energy from faster increasing the temperature compared to commercial gas and other electric heater. This electrical fan heater is possible to be used in field of home, commercial and agricultural area for eco-energy saving heater.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.249-259
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• 2018

Radiation technology (RT) has long been applied in various fields for increasing the safety and shelf-life of foods by controlling pathogen-induced poisoning. RT was introduced for the first time in Korea in the 1950s to eliminate harmful microorganisms in food materials. In the 1980s, RT had been scientifically proven to be effective for the sterilization of food and public health products. In recent years, irradiation with gamma rays has also been used for improving physiological properties through the structural modification of natural molecules, which has been proposed to be applicable to various industries. In particular, radiation transformation technology (RTT), which involves the development of new functional compounds through the molecular conversion of natural biomaterials, is becoming a new high-value technology as a fusion technique of RT and biotechnology. The present reports have suggested that RTT can be an effective tool for the development of new functional compounds and improvement of the physiological activity of biomolecules.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.2
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• pp.97-104
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• 2005

A simple but efficient grid generation technique by using the modified compressible form of stream function has been formulated. Transformation of a physical plane to a streamline plane, the Von Mises Transformation, has been widely used to solve the differential equations governing flow phenomena, however, limitation arises in low velocity region of boundary layer, mixing layer and wake region where the relatively large grid spacing is inevitable. Modified Von Mises Transformation with simple mathematical adjustment for the stream function is suggested and applied to solve the confined coaxial turbulent jet mixing with simple $\kappa-\epsilon$ turbulence model. Comparison with several experimental data of axial mean velocity, turbulent kinetic energy, and Reynolds shear stress distribution shows quite good agreement in the mixing layer except in the centerline where the turbulent kinetic energy distributions were somewhat under estimated. This formulation is strongly suggested to be utilized specially for free turbulent mixing layers in axisymmetric flow conditions such as the investigation of mixing behavior, jet noise production and reduction for Turbofan engines.

• Journal of the Chungcheong Mathematical Society
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• v.6 no.1
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• pp.113-130
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• 1993

In this paper, we introduce certain subgroups $E^{Rel}_n$ (X, Y, K, G) of the relative homotopy groups ${\sigma}_n$(X, Y, K, G) of a transformation group and examine the algebraic properties of these groups.

• Journal of the Chungcheong Mathematical Society
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• v.5 no.1
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• pp.9-21
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• 1992

We define a certain subgroup $E_n$ (X, K, G) of the relative homotopy groups of a transformation group ${\sigma}_n$(X, K, G). The algebraic properties of these groups are examined.