• Transactions of Materials Processing
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• v.27 no.1
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• pp.5-11
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• 2018

Direct energy deposition (DED) technique uses a laser heat source to deposit a metal layer on a substrate. Many researchers have used the DED technique to study the hardfacing of molds and dies. The aim of this study is to obtain high surface hardness and a sound bonding between the AISI M4 deposits and a substrate utilizing a mixed powder that contains M4 and AISI P21 powders. To prevent interfacial cracks between the M4 deposits and the substrate, the mixed powder is pre-deposited onto a JIS S45C substrate, before the deposition of M4 powders. Interfacial defects occurring between the deposits and substrate and changes in the microhardness of the intermediate layer were examined. Observations of the cross-sections of deposited specimens revealed that the interfacial cracks appeared in samples with one and two mixed layers regardless of the mixture ratio. However, the crack was removed by increasing the mixture ratio and the number of intermediate layers. Meanwhile, the microhardness in the mixed layer was found to decrease with increasing ratio of P21 powder in the mixture and that in the upper region of the deposited layers was approximately 800 HV, which was attributed to various alloying elements in the M4 powder.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.2
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• pp.64-67
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• 2004

In this paper, to discover the brightness improvement of ZnS:Cu powder electroluminescence (EL), a new structure is proposed in which phosphor and dielectric are mixed between electrodes. Dielectric and phosphor material are BaTiO$_3$ and ZnS:Cu, respectively. The effect of the mixed layer on EL sample is considered the improvement of source efficiency. Although the number of electrons introduced into the phosphor increases only modestly, the high electric field region of phosphor grains increases comparatively in the characteristics of brightness-voltage. Furthermore, the relaxation occurs through leading and trailing edge pairs, which is relatively efficient in characteristics of decay time. With these results, we found that the brightness of newly proposed ZnS:Cu powder electroluminescence was 167.24 cd/$m^2$ at ac voltage of 100V and frequency of 400Hz.

• Journal of Power System Engineering
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• v.11 no.2
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• pp.44-50
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• 2007

The oxidation behavior of commercial pure titanium is investigated in the temperature range of $727^{\circ}C{\sim}950^{\circ}C$ in mixed gases. The weight change is measured by TGA during oxidation in mixed gases. The oxidation behavior indicated by weight gain or the growth of oxide layer is based on the linear rate law at high temperatures. The structure of the oxide scale formed during oxidation is analysed by optical microscopy, electron probe microanalyzer, scanning electron microscope and x-ray diffraction. Oxide scales have a $TiO_2$ structure, and are constituted with multi-layered or two layered porous external one and a dense internal one. Ti-O solid solution region is formed at the interface of metal and scale layer. The formation of oxide scale is influenced by the oxidation temperature, time, crystal structure and the condition of atmosphere.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1042-1045
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• 2006

The electrical and optical properties of electrophosphorescent organic light-emitting diodes (OLEDs) with modified hole blocking layer (HBL) were investigated. Well-known 2,9-dimethyl-4,7- diphenyl-1,10-phenanthroline (BCP) HBL is mixed with electrophosphorescent host material (4,4'-N,N'- dicarbazole-biphenyl: CBP) or electrophosphorescent dopant material (fac-tris(2-phenylpyridine) iridium: $Ir(ppy)_3$) or both. The highest external quantum efficiency was obtained in the device with $BCP-CBP-Ir(ppy)_3$ mixed HBL and we attribute this result to the additional charge recombination in mixed-HBL.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.403-406
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• 1998

Electroluminescence(EL) come from the light emission obtained by electrical excitation energy passing through a phosphor layer under applied high electrical field. The preparation and characterizations of light emitting ACPEL(alternating-current powder electroluminescent) cell based on two kinds of phosphor mixed ZnS:Mn, Cu and ZnS:Cu phosphor. Basic structure is ITO/Mixed Phosphor/insulator/Al sheet, each layer was mixed by binder, which concentration 11p for phosphor, 8p for insulator. Dielectric properties was investigated first and emission properties of P-LED based on ZnS:Mn,Cu/ZnS:Cu,Br mixture. Emission spectra exhibits two kinds of main peaks at 100V, 1kHz sinusoidal excitation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.4
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• pp.239-245
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• 2000

A copper-tungsten sintered alloy(WCu) has been friction-welded to a tough pitch copper (Cu) in order to investigate friction weldability. The maximum tensile strength of the SWu-Cu friction welded joints had cp to 96% of those of the Cu base metal under the condition of friction time 0.6sec, friction pressure 45MPa, upset pressure 125MPa and upset time 5.0sec. And it is confirmed that the tensile strength of friction welded joints are influenced highly by upset pressure rather than friction time. And it is considered that mixed layer was formed in the Cu adjacent side to the weld interface, W particles included in mixed layer induced fracture in the Cu adjacent side to the weld interface and also, thickness of mixed layer was reduced as upset pressure increase.

• Water for future
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• v.29 no.5
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• pp.235-244
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• 1996

A one-dimensional eddy diffusion model and a mixed-layer model are developed and applied to simulate the vertical temperature profiles in lakes. Also the running results of each method are compared and analyzed. In an eddy diffusion model, molecular diffusivity is neglected and eddy diffusivity which does not need lake-specific fitting parameter and constant lake's level are applied. The heat exchanges at the water surface and the bottom are formulated by the energy balance and zero energy gradient, respectively. In a mixed-layer model, two layers approach which has a constant thickness is adopted. Application of these models which use explicit finite difference an Runge-Kutta methods respectively demonstrates that the models efficiently simulate water temperatures.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.963-968
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• 1999

This study was tried to evaluate possibilities for discriminating the mixture degree of wheat flour from buckwheat products. Buckwheat was milled into four grades of powder, i.e. whole grain flour (WGF), inner layer flour(ILF), middle layer flour(MLF) and outer layer flour(OLF)), and these powders were mixed with wheat flour(WF) to make mixed samples. Ash, protein and fat contents of the buckwheat flours were high in the order of OLF=WGF>MLF>ILF. On the other hand, WF showed a similar content to OLF in ash and protein, and to ILF in fats. Potassium and magnesium contents were higher in all the buckwheat powder than in the wheat flour. Flavonoid contents were higher in order of OLF>WGF=MLF> ILF, but it was not in wheat flour. Although the reliable correlation between mix ratio and components, i.e. mag nesium or ash analyzed were found, it did not seem to reflect sufficiently the expected variations of contents of original material components. Also, compositions of commercial buckwheat products were analyzed to evaluate the mixed ratio of buckwheat flour and wheat flour. The results suggest that the components analyzed in this study as putative marker were not good in determining whether or how much buckwheat products contained wheat flour.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.1
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• pp.107-112
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• 2018

One-dimensional numerical model is implemented to investigate temperature variations in the mixed layer depth (MLD) with the passage of typhoons. In the model, we assume a non-divergent, infinite ocean and consider wind effects only, excluding isostatic effects (inverse barometric effects) and upwelling with vertical movement of the water column. Numerical experiments investigate the effects of typhoon tracks on temperature variations, including their dependence on vertical resolutions in the MLD and these results are compared with those in a three-dimensional primitive equation model (POM). The model reproduces features of the observed temperature variations in the MLD fairly well, and implies that wind effects, rather than isostatic effects, play a predominant role in temporal and spatial temperature variations in the MLD. After the passage of typhoons, however, the model does not reproduce well the temperature variations observed in the MLD, because a limitation of the model is its inability to reproduce events such as cyclonic eddy formation (Hong et al., 2011; Masuda and Hong, 2011). The model also shows well the so called 'rightward bias' (Price, 1981) of sea surface cooling which is the most predominant in the right hand side of typhoon's track.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.2
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• pp.121-125
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• 2014

In this research, nanocomposite layers consisting of poly (3,4,-ethylene dioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) and CuO nanoparticles were investigated as hole transport layers in organic solar cells based on poly (3-hexylthiophene) (P3HT) as the electron donor and (6.6) phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor. The addition of CuO nanoparticles to PEDOT:PSS layer improved the solar cell performance with 0.5% CuO nanoparticle concentration. At optimized concentration, CuO mixed PEDOT:PSS films had good electrical ($4.131{\Omega}{\cdot}cm$) and optical (transmittance > 90%) properties for using hole transporting layer. We investigated that improved solar cell performance with CuO nanoparticles mixed PEDOT:PSS films.