• Korean Journal of Metals and Materials
• /
• v.47 no.3
• /
• pp.147-154
• /
• 2009

The effect of carbon addition on the microstructures and mechanical properties of $Ni_3Al$ and TiAl intermetallic alloys have been characterized. It is shown that carbon is not only an efficient solid solution strengthener in $Ni_3Al$ and TiAl, it is also an efficient precipitation strengthener by fine dispersion of carbide. Transmission electron microscope investigation has been performed on the particle-dislocation interactions in $Ni_3Al$ and TiAl intermetallics containing various types of fine precipitates. In an $L1_2$-ordered $Ni_3Al$ alloy with 4 mol.% of chromium and 0.2~3.0 mol.% of carbon, fine octahedral precipitates of $M_{23}C_6$ type carbide, which has the cube-cube orientation relationship with the matrix, appear during aging. Typical Orowan loops are formed in $Ni_3Al$ containing fine dispersions of $M_{23}C_6$ particles. In the L10-ordered TiAl containing 0.1~2.0 mol.% carbon, TEM observations revealed that needle-like precipitates, which lie only in one direction parallel to the [001] axis of the $L1_0$ matrix, appear in the matrix and preferentially at dislocations. Selected area electron diffraction (SAED) patterns analyses have shown that the needle-shaped precipitate is $Ti_3AlC$ of perovskite type. The orientation relationship between the $Ti_3AlC$ and the $L1_0$ matrix is found to be $(001)_{Ti3AlC}//(001)_{L10\;matrix}$ and $[010]_{Ti3AlC}//[010]_{L10\;matrix}$. By aging at higher temperatures or for longer period at 1073 K, plate-like precipitates of $Ti_2AlC$ with a hexagonal structure are formed on the {111} planes of the $L1_0$ matrix. The orientation relationship between the $(0001)_{Ti2AlC}//(111)_{L10\;matrix}$ is and $[1120]_{Ti2AlC}//[101]_{L10\;matrix}$. High temperature strength of TiAl increases appreciably by the precipitation of fine carbide. Dislocations bypass the carbide needles at further higher temperatures.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.28 no.1
• /
• pp.1-8
• /
• 2018

The 23 wt% polyvinylidene fluoride (PVDF)/15 wt% polyurethane (PU) fibers were electrospun using the conjugated nozzle at a flow rate of 1.0 mL/h and an electric field of 1 kV/cm. The formation of ${\beta}$ crystal phase in the PVDF and the PVDF/PU fibers was confirmed by Fourier transform infrared spectroscopy. After electrospinning, the asspun fibers were immersed in a boiling water and then dried at $100^{\circ}C$ in a convection oven to make a crimp phenomenon. The crimps with a diameter of $2.0{\pm}0.08{\mu}m$ were observed for the PVDF/PU fibers after hydrothermal treatment without sacrificing the extent of ${\beta}$ crystal phase. All the PU, PVDF and PVDF/PU fibers exhibited average cell viability of more than 98 %. The cell proliferation results suggested that L-929 cells adhered well to the PU, PVDF and PVDF/PU fibers and proliferated continuously with increasing time, indicating that the PVDF/PU fibers are highly applicable to the biomedical applications.

• Journal of information and communication convergence engineering
• /
• v.3 no.3
• /
• pp.146-151
• /
• 2005

This paper represents an attempt to bring together and analyses the measurement data measured by the Satellite Signal Monitoring Center in Korea and the Korea Meteorological Administration/Korea Meteorological Research Institute in close cooperation with this study team. This paper presents the signal characteristic of GEO satellite operating in frequency range 1 to 20GHz associated with Asian Sand Dust (the so-called Yellow Sand Dust). The downlink signal power (dBm) for L-, S-, C-, Ku-, and Ka-band frequencies from GEO satellites were measured in a clear weather and in Asian Sand Dust weather by the Satellite Signal Monitoring Center. The measured signal power(dBm) were compared to the total number concentration and size distribution of Sand Dust that were measured by the Korea Meteorological Administration/Korea Meteorological Research Institute and the possible correlation between these sets data were analyzed. The results demonstrate that the downlink signal level (dBm) of GEO satellite is attenuated by Asian Sand Dust. Hitherto, merger information has been reported as to the influence of sand dust on satellite communications operating in regions affected by sand dust.

• Proceedings of the Safety Management and Science Conference
• /
• 2002.11a
• /
• pp.273-277
• /
• 2002

In the electrode fabrication of unit cell, we found that optimal the electrochemical characteristics were obtained with at 90 wt.% of activated carbon(BP-20), 5 wt.% of conducting agent(Ppy, Super P) and 5 wt.% of P(VdF-co-HFP)/PVP mixed binder. The electrochemical characteristics of unit cell with Ppy improver were as follows : 37.6 F/g of specific capacitance, 0.98 $\Omega$ of AC-ESR, 2.92 Wh/kg and 6.05 Wh/L of energy density, and 754 W/kg and 1,562 W/L of power density. It was confirmed that internal resistance were reduced due to the increase of electrical conductivity and filling density by the introduction of conductivity agent, and content of conducting agent was suitable in the range of 4~6 wt.%. According to the impedance measurement of the electrode with conductivity agent, we found that it was possible to charge rapidly by the fast steady-state current convergence due to low equivalent series resistance(AC-ESR), fast charge transfer rate at interface between electrode and electrolyte, and low RC time constant.

• Applied Science and Convergence Technology
• /
• v.25 no.3
• /
• pp.61-65
• /
• 2016

Here, the rapid detection of Salmonella typhimurium by a portable surface plasmon resonance (SPR) biosensor in which the beam from a diode laser is modulated by a rotating mirror is reported. Using this system, immunoassay based on lipopolysaccharides (LPS)-specific monoclonal anti-Salmonella antibody was performed. For the purpose of orientation-controlled immobilization of antibodies on the SPR chip surface, the cysteine-mediated immobilization method, which is based on interaction between a gold surface and a thiol group (-SH) of cysteine, was adopted. As a result, using the portable SPR-based immunoassay, we detected S. typhimurium in the range from 10^7 CFU/mL to 10^9 CFU/mL within 1 hour. The results indicate that the portable SPR system could be potentially applied for general laboratory detection as well as on-site monitoring of foodborne, clinical, and environmental agents of interest.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.1
• /
• pp.39-46
• /
• 2014

In this paper, to operate 2.4 GHz Inverted-L antenna with On-Board Broadband characteristics is proposed. The antenna was designed on the system board, the bandwidth by adjusting the reactance of the antenna that was formed common-mode and differential-mode on the antenna stubs has been improved. The system size is $80mm{\times}60mm$, the size of the antenna was limited to $30mm{\times}60mm$, the thickness of FR4 dielectric substrate is 0.8 mm, FR4 dielectric constant 4.4 is used. The experimental results, the bandwidth from 17.2 to 24.1 %, the gain is 3.01~4.71 dB, omni-directional radiation pattern characteristics were obtained. By a mobile terminal design applying the results of the paper, the handset's price competitiveness and production efficiency can be improved.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.45 no.1
• /
• pp.77-85
• /
• 2019

OMiYakSung theory consists of various herbs that contain at least one or more of the five flavors. This theory has been used to prevent human diseases and enhance the immune system. The main objective of the present study was to investigate efficacy differences and changes in ingredients of blended and single herb extracts based on OMiYakSung theory. We selected three herbs Coptis japonica Makino, Cimicifuga heracleifolia Komarov, and white Poria cocos and assessed their physiological effect. As results, the blended extracts showed excellent cell migration effect at 400 ug/mL concentration, compared to the single extract. In addition, the blended extracts enhanced immune function by increasing the activity of dendritic cells and showed the highest antioxidant activity by DPPH assay and HPLC-ABTS assay. In this study, we developed a new materials that can be applicable to cosmetics and pharmaceuticals field by applying oriental medicine theory.

• The Journal of Korean Medicine
• /
• v.36 no.1
• /
• pp.9-21
• /
• 2015

Objectives: Realgar has been frequently used for skin disorders in history of herbal medicine. However, the efficacy of realgar has not been examined in atopic dermatitis(AD). In this study, the effects of realgar on AD were investigated, especially on pruritus and inflammation. Methods: AD lesions were induced in the shaved backs of BALB/c mice through repeated application of DNCB. The mice were treated for 11 days with 1% realgar ($100{\mu}L/day$). Histological changes in skin thickness were observed. The anti-pruritic effects of realgar were evaluated by the change in numbers of scratching behavior of mice and expression of substance P. The expressions of cytokines IL-4 and IL-6 were measured. Also, anti-inflammatory effects of realgar were examined on expressions of NF-${\kappa}B$, phospho-$I{\kappa}B{\alpha}$ and mitogen-activated protein kinases (MAPKs). Results: Realgar decreased skin thickness (both dermal and epidermal) 38% and 17% respectively, compared to positive control, DNCB group. The scratching behavior of mice was reduced by 42% and expression of substance P was significantly less. Cytokines IL-4 and IL-6 were significantly reduced by 52.6% and 77.6%, respectively. The expressions of NF-${\kappa}B$, phospho-$I{\kappa}B{\alpha}$ and MAPKs (phospho-ERK1/2, -p38 and -JNK) were significantly suppressed with marked effects on phospho-ERK1/2. Conclusions: The collective results suggest that realgar shows anti-pruritic and anti-inflammatory effects on AD. And realgar might be a potential therapeutic candidate for treatment of atopic dermatitis.

• Journal of the Korea Convergence Society
• /
• v.10 no.5
• /
• pp.149-156
• /
• 2019

This study adopts 'intersectionality' as a key concept of Sheila Levrant de Bretteville's design works. As a method of research, this research suggests the definition of intersectionality, from the idea of black feminism. Analysis of the features are such as 1) Typography of speech, 2) Collection of narrative, and 3) site specific installation. The inclusion of the various situations of the individuals reflected in the design throughout de Bretteville's works has made it possible to guarantee the intersectionality. De Bretteville overthrows the context of the power in which the design is placed, embracing forgotten or less illuminated positions. As a result, this research could derive three implications such as 1) visualization of invisibility, 2) subjectification of object, and 3) demarginalization of marginality. The perspective of the intersectionality are in line with the values of contemporary Korean society and might be an insight for researchers who want to establish a design philosophy.

• Atmosphere
• /
• v.24 no.1
• /
• pp.49-68
• /
• 2014

This study analyzed atmospheric conditions for the convergent cloud band (Cu-Cb line) in developing stage and its neighbouring convections formed over the East Sea on 1 February 2012, by using synoptic, satellites data, and WRF numerical simulation output of high resolution. In both satellite images and the WRF numerical simulation outputs, the Cu-Cb line that stretched out toward northwest-southeast was shown in the East Sea, and cloud lines of the L mode were aligned in accordance with the prevailing surface wind direction. However, those of the T mode were aligned in the direction of NE-SW, which was nearly perpendicular direction to the surface winds. The directions of the wind shear vectors connecting top winds and bottom winds of the moist layers of the L mode and the T mode were identical with those of the cloud lines of L mode and T mode, respectively. From the WRF simulation convection circulations with a convergence in the lower layer of atmosphere and a divergence above 1.5 km ASL (Above Sea Level) were identified in the Cu-Cb line. A series of small sized vortexes (maximum vortex: $320{\times}10^{-5}s^{-1}$) of meso-${\gamma}$-scale formed by convergences was found along the Cu-Cb lines, suggesting that Cu-Cb lines, consisting of numerous convective clouds, were closely associated with a series of the small vortexes. There was an absolute unstable layer (${\partial}{\theta}/{\partial}z$ < 0) between sfc and ~0.3 km ASL, and a stable layer (${\partial}{\theta}/{\partial}z$ > 0) above ~2 km ASL over the Cu-Cb line and cloud zones. Not only convectively unstable layers (${\partial}{\theta}_e/{\partial}z$ < 0) but also neutral layers (${\partial}{\theta}_e/{\partial}z{\approx}=0$) in the lower atmosphere (sfc~1.5 km ASL) were scattered around over the cloud zones. Particularly, for the Cu-Cb line there were convectively unstable layers in the surface layer, and neutral layers (${\partial}{\theta}_e/{\partial}z{\approx}=0$) between 0.2 and ~1.5 km ASL over near the center of the Cu-Cb line, and the neutralization of unstable layers came from the release of convective instability.