• Corrosion Science and Technology
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• v.15 no.6
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• pp.265-270
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• 2016

The ellipso-microscopic observation of a titanium surface undergoing anodization in $0.05mol\;dm^{-3}$ of $H_2SO_4$ was conducted. During irradiation by ultra-violet (UV) light with a wavelength of 325 nm, the titanium surface allowed for the flow of a photo-induced current and showed up as a bright, patch-like image on an ellipso-microscopic view. The brightness and patch-pattern in the image changed with flowing photo-induced current. The changes in the brightness and the image corresponded to the formation and/or degradation of titanium oxide due to the photo-electrochemical reaction of the oxide. An in situ monitoring using the ellipso-microscope revealed that the film change was dependent on the irradiation light power, by UV-light increases the anodic current and results in the initiation of pitting at lower potentials as compared with the non-irradiated condition.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.3
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• pp.15-30
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• 2004

In this paper, an analytical modeling for the dark and photo-current characteristics of a buried-gate short- channel GaAs MESFET is presented. The presented model shows that the increase of drain current under illumination is largely due to not the increase of photo-conductivity in the neutral region but the narrowing effect of the depletion layer width. The carrier density profile within the neutral region is derived from solving the carrier continuity equation one-dimensionally. In deriving the photo-generated current, we assume that the photo-current is compensated with the thermionic emission current at the gate-channel interface. Moreover, the two-dimensional Poisson's equation is solved by taking into account the drain-induced longitudinal field effect. In conclusion, the proposed model seems to provide a reasonable explanation for the dark and photo current characteristics in a unified manner.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.4
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• pp.404-409
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• 2004

We fabricated photo-sensor for fluorescence detection in LOC. LOC is high throughput screening system. Our LOC screens biochemical reaction of protein using the immunoassay, and converts biochemical reaction into electrical signal using LIF(Laser Induced Fluorescence) detection method. Protein is labeled with rhodamine intercalating dye and finger PIN photodiode is used as photo-sensor We measured fluorescence emission of rhodamine dye and analyzed tendency of fluorescence detection, according to photo-sensor size, light intensity, and rhodamine concentration. Detection current was almost linearly proportional to two parameters, intensity and concentration, and was inversely proportional to photo-sensor size. Integrated LOC consists of optical-filter deposited photo-sensor and PDMS microchannel detected 50 (pg/${mu}ell$) rhodamine. For integrated LOC including light source, we used green LED as the light source and measured emitted fluorescence.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.10-11
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• 2006

The azobenzene dendrimer is one of the dendrimeric macromolecules that include the azo-group exhibiting a photochromic character. Due to the presence of the charge transfer element of the azo-group and its rod-shaped structure, these compounds are expected to have potential interest in electronics and photoelectronics, especially in nonlinear optics. In the present paper, we give pressure stimulation to organic thin films and detect the induced displacement current. Functional photoisometrization organic molecular the photo-stimulus to organic monomolecular L films and LB films of dendrimer and SASH were performed. The SASH organic monolayer in case of pressure stimulus occurred that positive course but in case of the photo-stimulus compared positive and negative. It is assumed that generation forms of displacement current were measured when photo-stimulus for impression.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.281-284
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• 2004

Photo-induced memory effect of an organic light-emitting diode(OLED) composed of a hydrazone-derivative(DBAH) dispersed in bis-phenol-A type polycarbonate polymer(PCA) in the presence of thio-Michler's ketone, was investigated by the measuring of the current density and luminance at the various conditions. After the light exposure, the current of the OLED was decreased approximately one order, and the luminance of the OLED also decresed. This memory effct was erasable by heating the OLED to the temperature higher than the glass transition temperature(Tg). As shown in this result, we found the memory effect was erased by heating and returned to its original state in the hole injecting layer(HIL) of the OLED. A series of these phenomena was suggested the possibility of the application to the imaging plate.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.827-832
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• 2008

A new diarylethene compound with donor and acceptor substituent was synthesized from 2,3-bis(2-methylbenzo[b]thiophene-3-yl)hexafluorocyclopentene (BTF) over 5 steps. The donor-acceptor structured BTF compound (TBTFE) showed spectral change to a longer wavelength through photochromism with a high cyclization quantum yield (0.56). The 3,4-ethylenedioxythiophene (T) and carboethoxy (E) groups directly connected to BTF unit promoted electrical change accompanied with the photoisomerization of the BTF unit. Photo-induced electrical switching was achieved from a photocell containing TBTFE doped polymer film, which showed reversible and stable current change over repeated cycles by the alternative UV/Vis irradiation, as estimated by the I-V plot.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.956-958
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• 1999

We designed and fabricated p-type MOSFETs with floating gate in n-type well lesion and examined their photo characteristics. The fabricated MOBFETs showed a high photo-respsonse characteristics, indicating a possibility as a photo sensor. The structures of MOSFETs were changed as to the number of gate and channel. As the number of channel increased, the induced current by light source s increased. However, the effect of the number of gate was negligble on the photo-response characteristics of the device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.497-500
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• 2001

Due to their better photosensitivity in X-ray, the amorphous selenium based photoreceptor is widely used on the X-ray conversion materials. It was possible to control the charge carrier transport of amorphous selenium by suitably alloying a-Se with other elements(e,g. As, Cl). The charge transport properties of amorphous Selenium is decided on hole which is induced from metal to selenium in metal-selenium junction and which is transferred in a-Se bulk. This phenomenon is resulted of changing electric field owing to increasing of space charge by deep trap of a-Se bulk. In this paper, We dopped the chlorine to compensate deep hole trap and deposited blocking layer using dielectric material to prevent from increasing space charge for injection charge between metal electrode and a-Se layer. We compared space charge and the decreasing of trap density through measuring dark and photo current.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.586-590
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• 2006

Dendrimers represent a new class of synthetic macromoleculcs characterized by a regularly branched treelike structure. Multiple branching yields a large number of chain ends that distinguish dendrimers from conventional star-like polymers and microgels. The azobenzene dendrimer is one of the dendrimeric macromolecules that include the azo-group exhibiting a photochromic character. Due to the presence of the charge transfer element of the azo-group and its rod-shaped structure, these compounds are expected to have potential interest in electronics and photoelectronics, especially in nonlinear optics. In the present paper, we give pressure stimulation to organic thin films and detect the induced displacement current. Functional photoisometrization organic molecular the photo-stimulus to organic monomolecular L films and LB films of dendrimer and 8A5H were performed. The 8A5H organic monolayer in case of pressure stimulus occurred that positive course but in case of the photo-stimulus compared positive and negative. It is assumed that generation forms of displacement current were measured when photo-stimulus for impression.

• Korean Journal of Plant Resources
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• v.32 no.3
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• pp.207-219
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• 2019

Ultraviolet (UV) radiation is associated with the development of extrinsic skin aging. We performed in vivo assays in order to investigate the protective effect of a combination of grapefruit and rosemary extracts (cG&Re) on UVB-induced skin aging. The results indicated that cG&Re displayed elastase inhibitory activity in a dose-dependent manner. Topical application of cG&Re mitigated photo-aging related lesions such as skin erythema and thickening in photo-aged BALB/c mice dorsal skin, by preventing UVB-induced collagen degradation. Immunohistochemical analyses revealed that cG&Re stimulated SIRT-1 expression, and suppressed MMP-1 and $IL-1{\beta}$ expression. It was observed that expression of MMP-1 and -13 mRNA was downregulated in the cG&Re-treated group. Furthermore, cG&Re treatment drastically suppressed protein expression of MMP-1 and regulated the phosphorylation of p-38 kinase. As expected, oral administration of cG&Re resulted in the same SIRT-1, MMP-1, and $IL-1{\beta}$ expression patterns observed upon topical application of cG&Re in the UV-induced mice model. Overall, the current results demonstrated that cG&Re attenuated both the downregulation of MMP-1 expression and up-regulation of SIRT-1 expression, as well as decreased phosphorylation of MAPK in UVB-induced skin ageing mice model, suggesting that cG&Re might be used as an internal food ingredient for beauty-purposes as well as a functional food material.