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Koo J.,National Korea Maritime University | Chang J.,National Korea Maritime University | Cho Y.-R.,Pusan National University | Okamoto K.,Kagawa University
Proceedings of International Meeting on Information Display | Year: 2010

We demonstrated an artificial sunlight using LED lamps with various wavelengths from UV to IR. Hence, the spectrum of it is much more close to the natural sunlight than commercial solar simulator. Using the LED-solar simulator, I-V characteristics of commercial solar cells were measured.


Oh S.,National Korea Maritime University | Jung M.,Tohoku University | Koo J.,National Korea Maritime University | Cho Y.,National Korea Maritime University | And 4 more authors.
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2010

We studied a kinetic model of the ZnO nanorod (NR) growth that occurs via vapor phase transportation (VPT). The mechanism of ZnO NR growth was discussed in terms of the length-to-diameter (LD) relationship of NRs, and it was confirmed by varying both the type of catalyst and source material used. Both theoretical calculations and experimental data indicated that elongation of NRs is primarily determined by diffusion of the absorbed atoms (adatoms) within a nominal migration length on the surface, which is not considered in the simple vaporliquidsolid model. © 2010 Elsevier B.V.


Koo J.,National Korea Maritime University | Park S.,Japan National Institute of Materials Science | Lee W.,Japan National Institute of Materials Science | Cho Y.,National Korea Maritime University | And 3 more authors.
Japanese Journal of Applied Physics | Year: 2013

A UV sensor was fabricated by screen printing indium-tin-oxide (ITO) nanocrystals on to quart glass. The initial printed ITO layer showed a resistivity too high for sensing applications, but considerable improvements were achieved through annealing under external pressure. The effects of this pressurized annealing were investigated using a commercial ITO film. The annealing aided the development of low-resistivity ITO through the repression of complex defects. The feasibility of the ITO sensor was confirmed through annealing coil-shaped ITO sensors under different conditions. Pressurized annealing greatly enhanced the output signal intensity under similar UV illumination conditions. © 2013 The Japan Society of Applied Physics.


Park K.,Pusan National University | Cho Y.-R.,Pusan National University | Song Y.-H.,Electronics and Telecommunications Research Institute | Chang J.,National Korea Maritime University
Proceedings of International Meeting on Information Display | Year: 2010

An anodizing surface treatment was demonstrated to Aluminum (Al6063) plate for heat sink application of light emitting diode (LED). The pitting corrosion caused by an anodizing increased specific surface area of the heat sink and improved heat-transfer properties of heat sink in LED module.


Koo J.E.,National Korea Maritime University | Lee S.T.,Korea University | Chang J.H.,National Korea Maritime University
Journal of Nanoscience and Nanotechnology | Year: 2015

We proposed a hybrid sensor which is able to detect both UV light and gas species. The sensor was fabricated by screen printing using indium-tin-oxide (ITO) nanocrystals. To improve the UV sensitivity, high temperature annealing (600°C) under an external pressure (0.2 MPa) was applied. We could observe room temperature operation of the sensor under the simultaneous stimulation of UV light and CH4 gas. This is indicating that an improved fire warning is possible by using the proposed hybrid sensor. Copyright © 2015 American Scientific Publishers All rights reserved.


Koo J.,National Korea Maritime University | Park S.,Japan National Institute of Materials Science | Lee W.,Japan National Institute of Materials Science | Cho Y.,National Korea Maritime University | And 3 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2013

We proposed an indium-tin-oxide (ITO) based gas sensor which can operate at room temperature. ITO nano-crystal was screen printed on a quartz substrate. To improve the sensitivity and to decrease the resistivity of the printed ITO layer, pressurized annealing was adopted. Resistivity of the printed ITO gas sensor decreased from 3.5 kΩcm to 1.56 Ωcm by pressurized annealing. We could observe room temperature operation of the printed ITO gas sensor by using various gases such as Ar, N2, O2 and CH4. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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