• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.516.1-516.1
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• 2006

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.687-690
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• 2009

It has been recently reported that nano-sized MgO single crystal powders emit ultraviolet by stimulation of electrons under vacuum condition. Therefore, in this study, nano-crystalline MgO powders were applied to a xenon plasma flat fluorescent lamp for LCD backlight to improve emission efficiency of the lamp by help of extra ultraviolet from nano-MgO. For comparison with nano-crystalline MgO powders, MgO nano-thin film was applied directly on phosphors inside a lamp panel through e-beam evaporation The luminance and efficiency of FFL with an addition of MgO nano-crystal powders on phosphors were improved by around 20%. Application of MgO thin film to phosphors worsened the emission characteristics of FFLs, even rather than FFL without MgO. The reason came from insufficient stimulation of phosphors by UV, crystallinity of MgO, and low secondary electron coefficient.

• Journal of Life Science
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• v.28 no.4
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• pp.465-471
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• 2018

Bee pollen is one of many types of alternative remedies, and it has been used for a long time throughout the world. It has numerous health effects, including antifungal, antibacterial, and antioxidant properties, immune modulation, enhanced cell proliferation, and even anti-carcinogenic effects. This study was designed to elucidate the effects of bee pollen on benign prostatic hyperplasia in rodents. For this experiment, we used nano-sized bee pollen produced through wet-grinding technology, thereby the extraction efficiency of the active ingredients in the bee pollen was significantly enhanced. First, We found that nano-sized bee pollen significantly reduced the size of prostates enlarged by chronic testosterone administration. In addition, nano-sized bee pollen significantly reduced the plasma concentration of the prostate-specific antigen (PSA). Interestingly, nano-sized bee pollen did not reduce the testosterone-induced increase in the plasma concentration of prostaglandin $E_2$ ($PGE_2$). The beneficial effects of nano-sized bee pollen in reducing both the size of the prostate and the plasma concentration of PSA was comparable to that of dutasteride. Finally, nano-sized bee pollen did not cause damage in LNCaP cells which are androgen-sensitive human prostate adenocarcinoma cells. Together, these data indicate that nano-sized bee pollen may be able to be used as a good alternative remedy for the treatment of benign prostatic hyperplasia.

• Applied Science and Convergence Technology
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• v.24 no.5
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• pp.184-189
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• 2015

We report a simple way to enhance the size gradient of an imprinted nanopattern through oxygen plasma etching under a nonuniform magnetic field. A sample substrate was placed next to a magnet, and then a nonuniform magnetic field condition was formed around the sample. Using oxygen plasma etching, a line pattern having an initial width of 273 nm was gradually modified from 248 nm at one end to 182 nm at the other end. Controlling the arrangement of the magnet and sample, we could induce a triangular shape size gradient. We verified that the gradually modified nanopatterns we produced are applicable to continual optical property control, showing a possibility to be utilized for optical components such as gratings and polarizers.

• Journal of Powder Materials
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• v.25 no.5
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• pp.384-389
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• 2018

Nanoparticles of PbTe are prepared via chemical reaction of the equimolar aqueous solutions of $Pb(CH_3COO)_2$ and Te at $120^{\circ}C$. The size of the obtained particles is 100 nm after calcination in a hydrogen atmosphere. Dense specimens for the thermoelectric characterization are produced by spark plasma sintering of prepared powders at $400^{\circ}C$ to $500^{\circ}C$ under 80 MPa for 5 min. The relative densities of the prepared specimens reach approximately 97% and are identified as cubic based on X-ray diffraction analyses. The thermoelectric properties are evaluated between $100^{\circ}C$ and $300^{\circ}C$ via electrical conductivity, Seebeck coefficient, and thermal conductivity. Compared with PbTe ingot, the reduction of the thermal conductivities by more than 30% is verified via phonon scattering at the grain boundaries, which thus contributes to the increase in the figure of merit.

• Journal of Information Display
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• v.8 no.3
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• pp.5-10
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• 2007

Twin target sputtering (TTS) system with a configuration of vertically parallel facing Al targets and a substrate holder perpendicular to the Al target plane has been designed to realize a direct Al cathode sputtering on organic light emitting diodes (OLEDs). The TTS system has a linear twin target gun with ladder type magnet array for effective and uniform confinement of high density plasma. It is shown that OLEDs with Al cathode deposited by the TTS show a relatvely lower leakage current density $({\sim}1{\times}10^{-5}mA/cm^2)$ at reverse bias of -6V, compared to that ($1{\times}10^{-2}{\sim}10^{-3}$ $mA/cm^2$ at -6V) of OLEDs with Al cathodes grown by conventional DC magnetron sputtering. In addition, it was found that Al cathode films prepared by TTS were amorphous structure with nanocrystallines due to low substrate temperature. This demonstrates that there is no plasma damage caused by the bombardment of energetic particles. This indicates that the TTS system with ladder type magnet array could be useful plasma damage free deposition technique for direct Al cathode sputtering on OLEDs or flexible OLEDs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.74-75
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• 2007

We report on the characteristics of organic light-emitting diodes with Al cathode deposited by specially designed twin target sputter(TTS) system. It was found that the Al cathode films grown by TTS system were amorphous structure with nanocrystallines due to low substrate temperature during sputtering process. Effective confinement of high-density plasma between two Al targets lead to low temperature sputtering process on organic layer. Moreover, organic light-emitting diodes with Al cathode deposited by TTS system exhibited low leakage current density of $4{\times}10^{-6}\;mA/cm2$ at -6 V indicating plasma damage due to bombardment of energetic particles such as ions and $\gamma$-electrons was effectively restricted in the ITS system. Sputtering method using ITS system is expected to be applied in organic electronics and flexible displays due to its low temperature and plasma damage free deposition process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.1
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• pp.20-24
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• 2006

Iridium-catalyzed carbon nanofilaments were formed on MgO substrate as a function of the gap between the substrate and the plasma using microwave plasma-enhanced chemical vapor deposition method. Under the remote plasma condition, carbon nanofibers were formed on the substrate. Under the adjacent plasma condition, on the other hand, carbon nanotubes-like materials instead of carbon nanofibers could be formed. When the substrate immersed into the plasma, any carbon nanofilaments formation couldn't be observed. During the reaction, the substrate temperatures were measured as a function of the gap. Based on these results, the cause for the different carbon nanofilaments formation according to the gap was discussed.

• Journal of Powder Materials
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• v.12 no.6 s.53
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• pp.422-427
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• 2005

The $Al_2O_3$ with various phases were prepared by simple ex-situ hydrolysis and spark plasma sintering (SPS) process of Al powder. The nano bayerite $(\beta-Al(OH)_3)$ phase was derived by hydrolysis of commercial powder of Al with micrometer size, whereas the bohemite (AlO(OH)) phase was obtained by hydrolysis of nano Al powder synthesized by pulsed wire evaporation (PWE) method. Compaction as well as dehydration of both nano bayerite and bohemite was carried out simultaneously by SPS method, which is used to fabricate dense powder compacts with a rapid heating rate of $100^{\circ}C$ per min. under the pressure of 50MPa. After compaction treatment in the temperature ranges from $100^{\circ}C\;to\; 1100^{\circ}C$, the bayerite and bohemite phases change into various alumina phases depending on the compaction temperatures. The bayerite shows phase transition of $Al(OH)_3{\to}{\eta}-Al_2O_3{\to}{\theta}-Al_2O_3{\to}\alpha-Al_2O_3$ sequences. On the other hand, the bohemite experiences the phase transition from AlO(OH) to ${\gamma}-Al_2O_3\;at\;350^{\circ}C.$ It shows AlO(OH) ${\gamma}-Al_2O_3{\to}{\delta}-Al_2O_3{\to}{\alpha}-Al_2O_3$ sequences. The ${\gamma}-Al_2O_3$ compacted at $550^{\circ}C$ shows a high surface area $(138m^2/g)$.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.55-60
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• 2020

The recent semiconductor packaging technology is evolving into a high-performance system-in-packaging (SIP) structure, and copper-to-copper bonding process becomes an important core technology to realize SIP. Copper-to-copper bonding process faces challenges such as copper oxidation and high temperature and high pressure process conditions. In this study, the bonding interface quality of low-temperature copper-to-copper bonding using a two-step plasma treatment was investigated through quantitative bonding strength measurements. Our two-step plasma treatment formed copper nitride layer on copper surface which enables low-temperature copper bonding. The bonding strength was evaluated by the four-point bending test method and the shear test method, and the average bonding shear strength was 30.40 MPa, showing that the copper-to-copper bonding process using a two-step plasma process had excellent bonding strength.