• Proceedings of the KWS Conference
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• 2006.10a
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• pp.120-122
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• 2006

This study deals with characterizations of microstructure and wear performance of a cladding layer, product on 1.9 mm-thick mild steel plate by the electric resistance welding, of composite metal powder of Coarse WC-6.5%Co and high carbon alloy(SHA). The cladding layer was examined and tested fur microstructural features, chemical composition, hardness, wear performance and wear mechanism. The cladding layer have two different matrix were observed by an optical microscope and EPMA. The one was the coarse WC-6.5Co structure. The other was the melted SHA with surrounding the WC-6.5Co structure. The hardness of WC-6.5Co was 1210HV. The hardness of SHA was 640HV. In comparison by wear rate, the cladding layer showed the remarkable wear performance that was 15 times of SM490 and about 62% of D2.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.5
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• pp.80-86
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• 1998

Material characterizations were performed for In$_{0.53}Ga_{0.47}As/In$_{0.52}Al_{0.48}$/As MQWs grown on InP substrates by low-temperature modlecular beam epitaxy. MQW samples were grwon at different temperatures of 200.deg.C, 300.deg. C and 500.deg. C, and doped with 10$^{18}$ cm$^{3}$ Be. High resolution x-ray diffraction measurement showed the change in crystal qualities according to growth temperature. Hall measurement showed the changes in carrier concentrations and mobilities for different growth temperatures. The optical properties of MQW samples were investigated with photoluminescence and fourier-transform infrared spectroscopy measurements.

• Carbon letters
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• v.28
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• pp.1-8
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• 2018

Graphene is a single atomic layer of carbon atoms, and has exceptional electrical, mechanical, and optical characteristics. It has been broadly utilized in the fields of material science, physics, chemistry, device fabrication, information, and biology. In this review paper, we briefly investigate the ideas, structure, characteristics, and fabrication techniques for graphene applications in lithium ion batteries (LIBs). In LIBs, a constant three-dimensional (3D) conductive system can adequately enhance the transportation of electrons and ions of the electrode material. The use of 3D graphene and graphene-expansion electrode materials can significantly upgrade LIBs characteristics to give higher electric conductivity, greater capacity, and good stability. This review demonstrates several recent advances in graphene-containing LIB electrode materials, and addresses probable trends into the future.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1598-1601
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• 2008

We describe the fabrication of transparent conducting single-walled carbon nanotubes (SWCNTs) film on flexible substrate following the conventional spin coating method. The fabricated film was post treated with diluted acid solution and its electrical and optical characterizations were performed. The electrical conductivity of SWCNTs film was enhanced and the film was found to be attached strongly with substrate after the post treatment.

• Journal of Welding and Joining
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• v.25 no.3
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• pp.72-77
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• 2007

This study deals with characterizations of microstructure and wear performance of a cladding layer, product on 1.9 mm-thick mild steel plate by the electric resistance welding, of composite metal powder of Coarse WC-6.5%Co and high carbon alloy (SHA). The cladding layer was examined and tested for microstructural features, chemical composition, hardness, and bondability. The cladding layer have two different matrix were observed by an optical microscope and EPMA. The one was the coarse WC-6.5Co structure. The other was the melted SHA with surrounding the WC-6.5Co structure. The hardness of WC-6.5Co was 1210HV. The hardness of SHA was 640HV.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.837-838
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• 2009

In this work, pyromellitic dianhydride (PMDA) was used as a cathode interfacial layer in the organic light emitting diodes (OLEDs) and its thickness was optimized. Various electrical and optical characterizations of the OLEDs having various thicknesses of the PMDA cathode interfacial layer revealed that the best OLED performance could be achieved by using 0.5 nm-thick PMDA layer compared to the control device without any interfacial layer.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.461-466
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• 1999

Diamond-like carbon(DLC) films were directly deposited onto germanium(Ge) witness pieces and lenses by a capacitively coupled 13.56 MHz RF glow discharge plasma with $CH_4$ gas. The characterizations of DLC films were measured using a Raman and FTIR spectrometer. The configuration of Raman and FTIR spectra had a traditional shape. The IR transmittance was measured using an IR spectrophotometer. The maximum values of the IR transmission of Ge with the DLC/Ge/DLC, DLC/Ge/BBAR (broad band antireflection), DLC/Ge, and BBAR/Ge structures are 98%, 93%, 64%, and 63.5%, respectively, which come up to the theoretical values. The uniform DLC films were obtained by a rotation of the cathode at certain conditions.

• Transactions on Electrical and Electronic Materials
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• v.9 no.2
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• pp.73-78
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• 2008

We investigated for comparison of large-area i-a-Si:H and p-a-SiC:H film quality like thickness uniformity, optical bandgap and surface roughness using both ICP-CVD and PECVD on the large-area substrate(diameter of 100 mm). As a whole, films using ICP-CVD could be achieved much uniform thickness and bandgap of that using PECVD. For i-a-Si:H films, its uniformity of thickness and optical bandgap were 2.8 % and 0.38 %, respectively. Also, thickness and optical bandgap of p-a-SiC:H films using ICP-CVD could be obtained at 1.8 % and 0.3 %, respectively. In case of surface roughness, average surface roughness (below 5 nm) of ICP-CVD film could be much better than that (below 30 nm) of PECVD film. HIT solar cell with 2 wt%-AZO/p-a-SiC:H/i-a-Si:H/c-Si/Ag structure was fabricated and characterized with diameter of 152.3 mm in this large-area ICP-CVD system. Conversion efficiency of 9.123 % was achieved with a practical area of $100\;mm\;{\times}\;100\;mm$, which can show the potential to fabrication of the large-area solar cell using ICP-CVD method.

• Journal of the Korean Vacuum Society
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• v.22 no.2
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• pp.98-104
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• 2013

$VO_2$ is an attractive thermochromic material, in which its electrical and optical properties can be switched by the structural phase-transition about $68^{\circ}C$. Recently, graphene is also a rising material which is researched as a transparent electrode because of its superior electrical and optical characteristics. In this respect, we try to fabricate the hybridized films using $VO_2$ and graphene on transparent sapphire substrate and then we investigate a structure and characterize an optical property for the samples as a function of temperature. According to the result of IR-transmittance analysis of $VO_2$ films as a function of temperature, the graphene-supported sapphire substrates are better about 10% than the bare sapphire substrates. The mean phase transition temperatures are also decreased as the number of graphene-layers increased and the hysteresis of phase transitions are narrowed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.3
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• pp.97-100
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• 2008

Polar and non-polar GaN was grown by the HVPE on various substrates and influence of polarity has been investigated. The $10\;{\mu}m$ thickness GaN were grown by HVPE is along A-plane ($11{\bar{2}}0$), C-plane (0001) and M-Plane ($10{\bar{1}}0$) sapphire substrate respectively. Surface properties were observed by optical microscope and atomic force microscopy. High resolution X-ray diffraction (HR-XRD) confirms the wurtzite structure. The donor band exciton peak located at ${\sim}3.4\;eV$ and also located yellow luminescence peak at 2.2 eV. The polarity of the GaN film has a strong influence on the morphology and the optical properties.