• Proceedings of the Korean Vacuum Society Conference
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• 2009.02a
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• pp.92.1-92.1
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• 2009

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.48.1-48.1
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• 2007

• Toxicological Research
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• v.20 no.4
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• pp.365-374
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• 2004

Inhalation toxicity, mutagenicity, and immunotoxicity tests were performed using a smoke generation system to investigate the safety of Herbrette, a tobacco substitute made with the leaves of Perilla frutescens. ICR mice were exposed to nicotine-free Herbrette smoke with concentrations of 0 (control), 4.08 $\pm$ 1.32 mg/$m^3$ (low dose), 7.72 $\pm$ 2.14 mg/$m^3$ (medium dose) and 12.83 $\pm$ 1.69 mg/$m^3$ (high dose) total particulate matters (TPM) for 4 weeks. When compared to the control group, the body weights, organ weights in the exposed groups did not show any significant differences. However, certain change of several serum chemical data and biochemical parameters were observed, however, the changes were within normal physiological ranges. Moreover, no changes in organ weight, and no gross/microscopic changes were observed between the exposed and control groups. Salmonella typhimurium reverse mutation, in vivo chromosomal aberration and micronucleus assays revealed that Herbrette did not induce mutagenicity. Upon evaluation of peripheral cellular immunity of mice through in vitro lymphocyte proliferation assay, no significant difference was observed in mean stimulation index between the exposed and control groups. Taken together, our results strongly suggest that Herbrette may not cause toxicity on mice under current condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.403-404
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.521-522
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• 2006

• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.395-400
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• 2007

We propose a design and analysis of an optical system using a prism with a high enough refractive index for wet fingerprint identification. Important parameters including the tilting angle($\beta$) of the $1^{st}$ image plane, an anamorphic distortion, and a tilt of image plane are considered in terms of the apex angle of the prism($\alpha$) and refractive index of the prism material. Our suggestion on refractive index and apex angle of the prism corroborates well with experimental results.

• Journal of the Korean institute of surface engineering
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• v.43 no.3
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• pp.121-126
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• 2010

The PS(porous Si) were fabricated with different anodization time and current density. The structural and optical properties of PS were investigated by SEM(scanning electron microscopy), AFM(atomic force microscopy), and PL(photoluminescence). It is found that the pore size and surface roughness of PS are proportional to the current density. The PL spectra show that the PL peak position is red-shifted with increasing anodization time. This behavior corresponds to the change of pore size which is consistent with the quantum confinement model. The FWHM(full width at half maximum) of PL peak is decreased from 97 to 51 nm and the PL peak position is blue-shifted with increasing current density up to 10 mA/$cm^2$. The PL peak intensity of the PS fabricated under 1 mA/$cm^2$ is the highest among samples.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.346.1-346.1
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• 2014

Porous nano crystalline $TiO_2$ is currently used as a working electrode in a dye-sensitized solar cell (DSSC). The conventional working electrode is comprised of absorption layer (particle size:~20 nm) and scattering layer (particle size:~300 nm). We inserted window layer with 10 nm particle size in order to increase transmittance and specific surface area of $TiO_2$. The electrochemical impedance spectroscope analysis was conducted to analysis characterization of the electronic behavior. The Bode phase plot and Nyquist plot were interpreted to confirm the internal resistance caused by the insertion of window layer and carrier lifetime. The photocurrent that occurred in working electrode, which is caused by rise in specific surface area, increased. Accordingly, it was found that insertion of window layer in the working electrode lead to not only effectively transmitting the light, but also increasing of specific surface area. Therefore, it was concluded that insertion of window layer contributes to high conversion efficiency of DSSCs.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.273.1-273.1
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• 2014

Graphene, a two dimensional plane structure of $sp^2$ bonding, has been promised for a new material in many scientific fields such as physics, chemistry, and so on due to the unique properties. Chemical vapor deposition (CVD) method using transitional metals as a catalyst can synthesize large scale graphene with high quality and transfer on other substrates. However, it is difficult to control the number of graphene layers. Therefore, it is important to manipulate the number of graphene layers. In this work, homogeneous solid solution of Cu and Ni was used to control the number of graphene layers. Each films with different thickness ratio of Cu and Ni were deposited on $SiO_2/Si$ substrate. After annealing, it was confirmed that the thickness ratio accords with the composition ratio by X-ray diffraction (XRD). The synthesized graphene from CVD was analyzed via raman spectroscopy, UV-vis spectroscopy, and 4-point probe to evaluate the properties. Therefore, the number of graphene layers at the same growth condition was controlled, and the correlation between mole fraction of Ni and the number of graphene layers was investigated.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.880-884
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• 2011

ZnO nanorods were grown by hydrothermal method. Two kinds of seed layers, Au film and island seed layers were prepared to investigate the effect of seed layer on ZnO nanorods. The ZnO nanorod on Au island seed layer has more unifom diameter and higher density compared to that of ZnO nanorod on Au film seed layer. The ZnO nanorods on Au island seed layer were annealed at various temperatures ranging from 300 to $850^{\circ}C$. The pinholes at the surface of the ZnO nanorods is formed as the annealing temperature is increased. It is noted that the pyramid structure on the surface of ZnO nanorod is observed at $850^{\circ}C$. The intensity of ZnO (002) diffraction peak in X-ray diffraction pattern and intensity of near band edge emission (NBE) peak in photoluminescence (PL) are increased as the ZnO nanorods were annealed at the temperature of $300^{\circ}C$.