• Journal of Environmental Science International
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• v.16 no.7
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• pp.785-791
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• 2007

The current study evaluated the technical feasibility of the application of titanium dioxide ($TiO_{2}$) photo-catalytic air cleaners for the disinfection of bioaerosols present in indoor air. The evaluation included both laboratory and field tests and the tests of hydraulic diameter (HD) and lamp type (LT). Disinfection efficiency of photocatalytic oxidation (PCO) technique was estimated by survival ratio of bacteria or fungi calculated from the number of viable cells which form colonies on the nutrient agar plates. It was suggested that the reactor coating with $TiO_{2}$ did not enhance the adsorption of bioaerosols, and that the UV irradiation has certain extent of disinfection efficiency. The disinfection efficiency increased as HD decreased, most likely due to the decrease in the light intensity since the distance of the catalyst from the light source increased when increasing the HD. It was further suggested that the mass transfer effects were not as important as the light intensity effects on the PCO disinfection efficiency of bioaerosols. Germicidal lamp was superior to the black lamp for the disinfection of airborne bacteria and fungi, which is supported by the finding that the disinfection efficiencies were higher when the germicidal lamp was used compared to the black lamp in the laboratory test. These findings, combined with operational attributes such as a low pressure drop across the reactor and ambient temperature operation, can make the PCO reactor a possible tool in the effort to improve indoor bioaerosol levels.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04b
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• pp.14-16
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• 2008

Built-in voltage in organic light-emitting diodes was studied using modulated photocurrent technique ambient conditions. From the bias voltage-dependent photocurrent, built-in voltage of the device is determined. The applied bias voltage when the magnitude of modulated photocurrent is zero corresponds to a built-in voltage. Built-in voltage in the device is generated due to a difference of work function of the anode and cathode. A device was made with a structure of anode/$Alq_3$/cathode to study a built-in voltage. ITO was used as an anode, and Al and LiAl were used as a cathode. A layer thickness of Al and LiAl were 100nm. Obtained built-in voltage is about 1.0V in the Al layer was used as a cathode. The obatined built-in voltage is about 1.6V in the LiAl layer was used as a cathode. The result of built-in voltage is dependent of cathode. We can see that the built-in voltage increase up to 0.4V when the LiAl layer was used as the cathode. These results correspond to the work function of LiAl which is lower than that of Al. As a result, the barrier height for an electron injection from the cathode to the organic layer could be lowered when the LiAl was used as a cathode.

• Particle and aerosol research
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• v.8 no.3
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• pp.111-120
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• 2012

In Daegu, a road cleaning system was constructed in the central part of the city and has been operated from April, 2011. We evaluated the effect of the system on the concentration of $PM_{10}$ at a roadside monitoring site. The ambient $PM_{10}$ concentration data were logged every 1 min for a period of 20 weeks from May to October, 2011, by means of light scattering method, and then every 5 min data were used in the statistical analysis. The measured data were verified by comparing them with beta-ray data obtained at the same site. Correlation coefficient between the two groups was highly significant (r=0.79), though the absolute levels of light scattering data appeared to be approximately 2.8 times higher than the beta-ray data. Diurnal, daily, weekly, and monthly variations of $PM_{10}$ data did not show any evidence of decreasing effect owing to the clean road system. A comparison of roadside $PM_{10}$ data with non-roadside data also revealed very similar pattern, implying the variation of the $PM_{10}$ concentrations is mainly affected by the traffic conditions near the monitoring site. However, if the operating conditions of the clean road system can be improved, i.e. increasing the frequency and duration of water cleaning, the road cleaning effect may improve the air quality indirectly by means of removing the resuspended particles from the road.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.6
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• pp.484-488
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• 2006

Alteration of illumination with optimum carbon dioxide fixation-based curve in this research successfully enhanced the $CO_{2}-fixation\;(q_CO_{2}$ capability of Chlorella vulgaris Buitenzorg cultivated in a bubble column photo bioreactor. The level of $CO_{2}$ fixation was up to 1.91 times that observed from cultivation with intensification of illumination on an optimum growth-based curve. During 144 h of cultivation, alteration of light intensity on an optimum $CO_{2}-fixation-based$ curve produced a $q_CO_{2}$ of $12.8\;h^{-1}$. Meanwhile, alteration of light intensity with a growth-based curve only produced a $q_CO_{2}$ of $6.68\;h^{-1}$. Increases in light intensity based on a curve of optimum $CO_{2}-fixation$ produced a final cell concentration of about 5.78 g/L. Both cultivation methods were carried out under ambient pressure at a temperature of $29^{\circ}C$ with a superficial gas velocity of $2.4\;m/h(U_{G}$. Cells were grown on Beneck medium in a 1.0 L Bubble Column Photo bioreactor illuminated by a Phillips Halogen Lamp (20 W/12 V/50 Hz). The inlet gas had a carbon dioxide content of 10%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2113-2118
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• 2016

Smart Jewelry is applied to the components of the Internet of Things. The process of obtaining the status information to the input of the sensor. And it controls the light color of the LED. Because to express the beauty of twinkling lights that can be felt in the jewelery and aesthetic functions were applied in order to feel the mystery. Smart Jewelry is capable of communication, interaction, wearable. Smart jewelery was equipped with a color, temperature, ambient light sensor. It was designed to allow interaction with a Bluetooth module. Applying an algorithm so that the light jewelry colors can vary depending on the circumstances of the smart jewelry wearer had been implemented by the mobile application. It can be realized in digital technology and the convergence of life. It presents the orientation development of the smart jewelery device on IoT environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.51-52
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• 2007

Built-in voltage in organic light-emitting diodes was studied using modulated photocurrent technique ambient conditions. From the bias voltage-dependent photocurrent, built-in voltage of the device is determined. The applied bias voltage when the magnitude of modulated photo current is zero corresponds to a built-in voltage. Built-in voltage in the device is generated due to a difference of work function of the anode and cathode. A device was made with a structure of anode/$Alq_3$/cathode to study a built-in voltage. ITO and ITO/PEDOT:PSS were used as an anode, and Al and LiF/AI were used as a cathode. It was found that an incorporation of PEDOT:PSS layer between the ITO and $Alq_3$ increases a built-in voltage by about 0.4V. This is consistent to a difference of a highest occupied energy states of ITO and PEDOT:PSS. This implies that a use of PEDOT:PSS layer in anode improves the efficiency of the device because of a lowering of anode barrier height. With a use bilayer cathode system LiF/Al, it was found that the built-in voltage increases as the LiF layer thickness increases in the thickness range of 0~1nm. For 1nm thick LiF layer, there is a lowering of electron barrier by about 0.2eV with respect to an Al-only device. It indicates that a very thin alkaline metal compound LiF lowers an electron barrier height.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.401-404
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• 2008

In the present investigation, a high precision thermal imprint system for micro ceramic products was developed and the net-shape manufacturing of multi-layer ceramic reflector for LED (Light Emitting Diode) was conducted with a precision metal die. Workpiece used in the present investigation were the multi-layer laminated ceramic sheets with pre-punched holes. The cavity with arbitrary angle was formed on the circular and rectangular holes of the ceramic sheets. During the imprinting process, the ambient temperature of the imprint system was kept over the transition temperature of the ceramic sheet and then rapidly cooled. The results in this paper show that the present method can be successfully applied to the fabrication of very small size hole array for ceramic reflector in a one step operation.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1668-1672
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• 2013

We developed a standoff Raman detection system for explosive molecules (EMs). Our system was composed of reflective telescope with 310 mm diameter lens, 532 nm pulse laser, and Intensified Charge-Coupled Device (ICCD) camera. In order to remove huge background noise coming from ambient light, laser pulses with nanosecond time width were fired to target sample and ICCD was gated to open only during the time when the scattered Raman signal from the sample arrived at ICCD camera. We performed standoff experiments with military EMs by putting the detector at 10, 20 and 30 m away from the source. The standoff results were compared with the confocal Raman results. Based on our standoff experiments, we were able to observe the peaks in the range of 1200 and $1600cm^{-1}$, where vibrational modes of nitro groups were appeared. The wave numbers and shapes of these peaks may serve as good references in detecting and identifying various EMs.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.20-23
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• 2000

We have investigated a process for the preparation of high-quality tantalum oxynitride ( $T_{a}$ $O_{x}$ $N_{y}$) via the N $H_3$ annealing of 7$_{a2}$ $O_{5}$, for use in gate dielectric applications. Compared with tantalum oxide (7$_{a2}$ $O_{5}$), a significant improvement in the dielectric constant was obtained by the N $H_3$ treatment. In addition, light reoxidation in a wet ambient at 45$0^{\circ}C$ resulted in a significantly reduced leakage current. We confirmed nitrogen incorporation in the tantalum oxynitride ( $T_{a}$ $O_{x}$ $N_{y}$ by Auger Electron Spectroscopy. By optimizing the nitridation and reoxidation process, we obtained an equivalent oxide thickness as thin as 1.6nm and a leakage current of less than 10mA/$\textrm{cm}^2$ at 1.5V..5V..5V..5V..5V..5V.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.2
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• pp.103-111
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• 2012

This paper introduces a novel concept of 'A Green LED Sensitivity Lighting System' which can automatically estimate QoS(quality of service) and emotional requirements of user using smart phone. And it can intelligently control ambient illumination lamp to conserve electric energy and to satisfy human sensitivity. The proposed system has 4 control modes; emotional lighting, smart lighting, green lighting and realistic lighting modes in order to comfort man's emotion, to maximize work efficiency, to save energy consumption and to make the entertainment more fun, respectively. When we choose green lighting mode for indoor office situations, an elaborate simulation shows that the proposed system with home network can reduce the energy by 50% compared to conventional light control system with a fixed time-based switching.