• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.268-279
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• 2003

The nano capsulation of the ceramide was a technique that capsulated ceramide III and tocopheryl linoleate at the mono-vesicle, so as to act the horny layer in skin. It was used 0.5-5.0 wt% of hydrogenated lecithin and 0.01~2.00 wt% of lysolecithin as the membrane-strengthen agents of the mono-vesicle, 5.0~10 wt% of propylene glycol and 5.0~10.0 wt% of ethyl alcohol made by high-pressure Microfluidizer. To enhance the moisturizing efficacy and treat an atopy skin, used ceramide III and tocopheryl linoleate as the active ingredients, and it was made the nano-capsule that synthetic emulsifiers were free. The optimal condition of capsulation of nano ceramide was as follows. The conditions were 3 times at 1,000bar and 60-7$0^{\circ}C$. The particle size showed 63.1$\pm$7.34 nm such as the transparence water as the results for measuring by the laser light scattering. A zeta potential value was -55.1$\pm$0.84 ㎷. The result of the clinical test, the moisturizing effect (in-vivo, n=8, p-value<0.05) was improved 21.15% compared to control, as well as it was improved 36.31 % before the treatment. Moreover, the effectiveness of atopy skin indicated positive reaction that patients were 10 volunteers.

• The Journal of the Acoustical Society of Korea
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• v.13 no.2
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• pp.30-37
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• 1994

Since the morden targets are of high speed and getting quiet in both active and passive mode, the necessities of developing advanced SONAR system capable of performing target motion analysis (TMA) and target classification are evident. In order to develop such a system, the scattering mechanism of complex bodies needs to be, some extent, fully understood and modeled. In this paper, MOving Spread Target(MOST) signal simulation model is presented and discussed. The model is based on the highlight distribution method, and simulates pulse elongation of spread target, doppler effect due to kinematics of the target as well as SONAR platform, and distribution target strength of each highlight point (HL) with directivity. The model can be used in developing and evaluating advanced SONAR system through system simulation, and can also be used in the development of target state estimation algorithm.

• Advances in nano research
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• v.3 no.2
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• pp.97-109
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• 2015

Citrate ion is a commonly used reductant in metal colloid synthesis, undergoes strong surface interaction with silver nanocrystallites. The slow crystal growth observed as a result of the interaction between the silver surface and the citrate ion makes this reduction process unique compared to other chemical and radiolytic synthetic methods. The antimicrobial effects of silver (Ag) ion or salts are well known, but the effects of citrate coated Ag nanoparticles (CAgNPs) are scant. Herein, we have isolated biofilm causative bacteria and fungi from drinking water PVC pipe lines. Stable CAgNPs were prepared and the formation of CAgNPs was confirmed by UV-visible spectroscopic analysis and recorded the localized surface plasmon resonance of CAgNPs at 430 nm. Fourier transform infrared spectroscopic analysis revealed C=O and O-H bending vibrations due to organic capping of silver responsible for the reduction and stabilization of the CAgNPs. X-ray diffraction micrograph indicated the face centered cubic structure of the formed CAgNPs, and morphological studies including size (average size 50 nm) were carried out using transmission electron microscopy. The hydrodynamic diameter (60.7 nm) and zeta potential (-27.6 mV) were measured using the dynamic light scattering technique. The antimicrobial activity of CAgNPs was evaluated (in vitro) against the isolated fungi, Gram-negative and Gram-positive bacteria using disc diffusion method and results revealed that CAgNPs with 170ppm concentration are having significant antimicrobial effects against an array of microbes tested.

• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.64-70
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• 2005

Target Strength(TS) is an important factor for the detection of the target in an active sonar system: thus the numerical model for the prediction of TS is widely being developed. For the frequency range of several kHz, the most important scattering mechanism is known to be specular reflection, which is largely affected by the geometrical shape of the target. In this paper, a numerical algorithm to predict TS is developed based on the Kirchhoff approximation which is computationally efficient. The developed algorithm is applied to the canonical targets of simple shapes, for which the analytical solutions exist. The numerical results show good agreement with the analytical solutions. Also, the algorithm is applied to more complex scatterers, and is compared with the experimental data obtained in the water tank experiment for the purpose of verifying the developed numerical model. Discussions on the effect of spatial sampling and other aspects of numerical m odeling are presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.638-642
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• 2014

In this study, we investigate on the crystal microstructure and magneto-resistance (MR) change of Bismuth(Bi) thin films for annealing process, in order to apply Bi thin films to the spin electronic devices. As-prepared Bi thin films show the randomly oriented find grains whose size was measured to about 100 nm and the very low MR (4.7 % at room temperature) while careful annealing results in not only grain growth up to ${\sim}2{\mu}m$ but also drastic MR improvement (404 % at room temperature). The drastic change in the MR after applying the annealing process is attributed to the grain growth decreasing grain boundary scattering of electron. Therefore, in this study, we confirm the annealing effect for the grain boundary formation and MR improvement of Bi thin films, and demonstrate the feasibility of spin electronic devices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.4
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• pp.198-202
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• 2018

In this work, we have investigated the effect of a 30-min thermal anneal at $550^{\circ}C$ on the electrical characteristics of neutron-irradiated 4H-SiC MOSFETs. Thermal annealing can recover the on/off characteristics of neutron-irradiated 4H-SiC MOSFETs. After thermal annealing, the interface-trap density decreased and the effective mobility increased in terms of the on-characteristics. This finding could be due to the improvement of the interfacial state from thermal annealing and the reduction in Coulomb scattering due to the reduction in interface traps. Additionally, in terms of the off-characteristics, the thermal annealing resulted in the recovery of the breakdown voltage and leakage current. After the thermal annealing, the number of positive trapped charges at the MOSFET interface was decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.145-146
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• 2007

Dye-Sensitized Solar Cell Solar cells(DSSC) were appeared for overcoming global environmental problems and lack of fossil fuel problems. And it is one of study field that is getting into the spotlight lately because manufacturing method is more simple and inexpensive than existing silicon solar cells. Oxide semiconductor is used for adsorption of dye and electron transfer in DSSC study, and $TiO_2$ is used most usually. Overall light conversion efficiency is changed by several elements such as $TiO_2$ particle size and structure, pore size and shape. In this study, we report the solar cell performance of titania$(TiO_2)$ film electrodes with various particle sizes. $TiO_2$ particle size was 16 nm, 25 nm, and mixture of 16nm and 25 nm, and manufactured using Doctor blade method. When applied each $TiO_2$ film to DSSC, the best efficiency was found at 16nm of $TiO_2$ particle. 16nm of $TiO_2$ particle has the highest efficiency compared to the others, because particles with smaller diameters would adsorb more dye due to larger surface area. And in case of the mixture of 16nm and 25 nm, the surface area was smaller than expected. It is estimated that double layer is adsorbed a large amount of chemisorbed dye and improved light scattering leading due to efficiency concentration light than mono layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.379-380
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• 2007

The characteristics of a co-sputtered indium zinc tin oxide (IZTO) films prepared by dual target dc magnetron sputtering from IZO and ITO targets at a room temperature are investigated. Film properties, such as sheet resistance, optical transmittance, surface work function and surface roughness were examined as a function of ITO dc power at constant IZO dc power of 100 W. It was shown that the increase of the ITO dc power during co-sputtering of ITO and IZO target resulted in an increase of sheet resistance of the IZTO films. This can be attributed to high resistivity of ITO film prepared at room temperature. Surface smoothness and roughness were investigated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The synchrotron x-ray scattering results obtained from IZTO film with different ITO contents showed that introduction of ITO atoms into amorphous IZO film resulted in a crystallization of IZTO film with (222) preferred orientation due to low alc transition temperature of ITO film. However, the transmittance of the IZTO films with thickness of 150 nm is between 80 and 85 % at wavelength of 550 nm regardless of ITO content. Possible mechanism to explain the ITO and IZO co-sputtering effect on properties of IZTO is suggested.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.5
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• pp.571-579
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• 2013

The aggregation behaviors of silver nanoparticles (AgNPs) and titanium dioxide ($TiO_2$) nanoparticles were investigated. Time-resolved dynamic light scattering (DLS) was used to study the initial aggregation of AgNPs and $TiO_2$ over a range of mono (NaCl) and divalent ($CaCl_2$) electrolyte concentrations. The effects of pH, initial concentration of NPs and natural organic matters (NOM) on the aggregation of NPs were also investigated. The aggregation of both nanoparticles showed classical Derjaguin-Landau-Verwey-Overbeek (DLVO) type behavior. Divalent electrolyte was more efficient in destabilize the AgNPs and $TiO_2$ than monovalent electrolyte. The effect of pH on the aggregation of AgNPs was not significant. But the aggregation rate of $TiO_2$ was much higher with increasing pH. Higher NPs concentration leads to faster aggregation. Natural organic matter (NOM) was found to substantially hinder the aggregation of both AgNPs and $TiO_2$. This study found that the aggregation behavior of AgNPs and $TiO_2$ are closely associated with environmental factors such as ionic strength, pH, initial concentration of NPs and NOM.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.131-131
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• 2010

We compared the electrical, optical, structural, and interface properties of indium zinc oxide (IZO)-Ag-IZO and IZO-Au-IZO multilayer electrodes deposited by linear facing target sputtering system at room temperature for organic photovoltaics. The IZO-Ag-IZO and IZO-Au-IZO multilayer electrodes show a significant reduction in their sheet resistance (4.15 and 5.49 Ohm/square) and resistivity ($3.9{\times}10^{-5}$ and $5.5{\times}10^{-5}$Ohm-cm) with increasing thickness of the Ag and Au layers, respectively. In spite of its similar electrical properties, the optical transmittance of the IZO-Ag-IZO electrode is much higher than that of the IZO-Au-IZO electrode, due to the more effective antireflection effect of Ag than Au in the visible region. In addition, the Auger electron spectroscopy depth profile results for the IZO/Ag/IZO and IZO/Au/IZO multilayer electrodes showed no interfacial reaction between the IZO layer and Ag or Au layer, due to the low preparation temperature. To investigate in detail the Ag and Au structures on the bottom IZO electrode with increasing thickness, a synchrotron x-ray scattering examination was employed. Moreover, the OSC fabricated on the IZO-Ag-IZO electrode shows a higher power conversion efficiency (3.05%) than the OSC prepared on the IZO-Au-IZO electrode (2.66%), due to its high optical transmittance in the wavelength range of 400-600 nm, which is the absorption wavelength of the P3HT:PCBM active layer.