• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.124-129
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• 2006

We have developed a compact and cost-effective camera module on the basis of wafer-scale-replica processing. A multiple-layered structure of several aspheric lenses in a mobile-phone camera module is first assembled by bonding multiple glass-wafers on which 2-dimensional replica arrays of identical aspheric lenses are UV-embossed, followed by dicing the stacked wafers and packaging them with image sensor chips. This wafer-scale processing leads to at least 95% yield in mass-production, and potentially to a very slim phone with camera-module less than 2 mm in thickness. We have demonstrated a VGA camera module fabricated by the wafer-scale-replica processing with various UV-curable polymers having refractive indices between 1.4 and 1.6, and with three different glass-wafers of which both surfaces are embossed as aspheric lenses having $230{\mu}m$ sag-height and aspheric-coefficients of lens polynomials up to tenth-order. We have found that precise compensation in material shrinkage of the polymer materials is one of the most technical challenges, in orderto achieve a higher resolution in wafer-scaled lenses for mobile-phone camera modules.

• The Journal of the Korea Contents Association
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• v.10 no.7
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• pp.40-48
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• 2010

Reflected-Ultraviolet photography is applied to the evidence of crime, Archaeology, and Dermatology. In the past, Ultraviolet photography was done with standard black-and-white film. Because emulsion of film is more sensitive to near UV light than CCD(Charge Coupled Device) or CMOS(Complementary Metal-Oxide-Semiconductor)of digital camera. In this research, we purpose to improve qulity of ultraviolet photographs and to find out the best alternative digital camera by utilizing a cunsumer digital camera. To achieve theses, we removed IR cutoff filter from digital camera. And by using modified UV pass filter, we verified the increase of image resolution of digital ultraviolet photographs. Also, we analyze reproducibility of digital ultraviolet photographs according to type, size, pixel of image sensor. Furthermore, this research resulted in the development of an practical digital camera system by utilizing a cunsumer digital camera. Eventually, it will contribute to practical use in the various field of digital ultraviolet photographs

• Textile Coloration and Finishing
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• v.21 no.5
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• pp.51-57
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• 2009

Since heavy metal pollution is a significant global environmental problem and very dangerous to human health, the improved methods for detecting heavy metals are required recently. Colorimetric chemosensors are now considered as one of the most effective analytical method used in the environment monitoring. New direct dyes having the function of colorimetric chemosensors were synthesized. When metal ions such as $Al^{3+}$, $Ca^{2+}$, $Cd^{2+}$, $Cr^{3+}$, $Cu^{2+}$, $Fe^{2+}$, $Fe^{3+}$, $Hg^{2+}$, $Li^+$, $Mg^{2+}$, $Na^+$, $Ni^{2+}$, $Pb^{2+}$ and $Zn^{2+}$ were added each solution of new direct dyes, the color of solution was changed and can be easily detected with naked eyes without expensive experimental equipment such as atomic absorption spectrometer (AAS) or inductively coupled plasma?mass spectrometer (ICP-MS). The new benzidine analogues were diazotized and reacted with couplers such as H-acid, J-acid, Chromotropic acid, Nevill-winther acid and gamma acid to synthesize new direct dyes. The structures of the new direct dyes were confirmed by high resolution mass spectrometer (FAB ionization) and evaluated with UV-Vis spectroscopy. The UV-VIS spectroscopy was measured for the dye solutions by adding various concentrations of metal ions. It was observed that the absorbance in UV-Vis spectra was changed as the heavy metal ions were added.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.472-477
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• 2017

Oil spills cause a lot of damage to the environment. Oil destroys the water environment and ecosystem in a very short period of time once they are contaminated by it, it takes a lot of time to recover from the contamination and the cleaning process is very difficult. Therefore, oil detectors are greatly needed as they can monitor any oil spills over the sea, rivers, and lakes. There are two kinds of technology available for detecting oil, viz. the contact and non-contact types. The former is based on the use of the conductivity, capacitance and microwaves, while the latter employs infrared, UV, laser, optic and radar technologies. As there are also various hurdles in the measuring of oil on water, such as the presence of waves, refraction of light, temperature and saltiness, it is imperative to select the right oil detector which is appropriate for the specific environment. In this study, a contact type oil detector is developed, which can be used in oil related industries, such as refineries, petrochemical companies, and power generation stations. The detector is made up of the sensor module, which floats on the water, and the controller which processes the signal coming from the sensor module and displays it. It is designed in such a way that the existence of oil is detected through the sensor and the change in the permittivity is observed to determine the volume and type of spilled oil.

• Polymer(Korea)
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• v.33 no.2
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• pp.111-117
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• 2009

This study aims to verify for humans the suitability of the enzyme-fixed hydrogel used for the patch sensor of the blood sugar testing system without blood sampling, which utilizes reverse iontophoresis. Using acrylate monomers, hydrogel was synthesized to which a certain unit of enzyme is fixed. In order to analyze the material property of the synthesized hydrogel, a structural analysis was performed using FT-IR spectroscopy, while the DSC was used to verify the thermal stability. In addition, with the UV-Vis spectrophotometer, it was verified that the degree of active enzyme is at least 50% greater than the standard product. The SEM was used to verify secure fixation of the enzyme onto the surface. As a result, it was observed that the enzyme is successfully fixed to the surface. Since the hydrogel makes direct contact with a patient's skin, it is essential to evaluate the toxicity when making direct contact with the skin. For that purpose, various sets of tests were undertaken according to the ISO 10993-cytotoxicity, intracutaneous reactivity, skin irritation test and maximization sensitization. Consequently, it was successfully verified that the enzyme-fixed hydrogel have bioavailability.

• Ocean Systems Engineering
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• v.9 no.4
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• pp.391-407
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• 2019

Tracking the location (position) of a surface or underwater marine vehicle is important as part of guidance and navigation. While the Global Positioning System (GPS) works well in an open sea environment but its use is limited whenever testing scaled-down models of such vehicles in the laboratory environment. This paper presents the design, development and implementation of a low energy ultrasonic augmented single beacon-based localization technique suitable for such requirements. The strategy consists of applying Extended Kalman Filter (EKF) to achieve location tracking from basic dynamic distance measurements of the moving model from a fixed beacon, while on-board motion sensor measures heading angle and velocity. Iterative application of the Extended Kalman Filter yields x and y co-ordinate positions of the moving model. Tests performed on a free-running ship model in a wave basin facility of dimension 30 m by 30 m by 3 m water depth validate the proposed model. The test results show quick convergence with an error of few centimeters in the estimated position of the ship model. The proposed technique has application in the real field scenario by replacing the ultrasonic sensor with industrial grade long range acoustic modem. As compared with the existing systems such as LBL, SBL, USBL and others localization techniques, the proposed technique can save deployment cost and also cut the cost on number of acoustic modems involved.

• KSTLE International Journal
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• v.8 no.1
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• pp.1-6
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• 2007

Chromatic device was developed using light emitting diodes, optic fibers and photodiodes. Chromatic ratio and total contamination parameters based on transmitted light intensity in Red, Green, and Blue wavelengths were used for oil chemical and particulate contamination assessment. Chromatic ratio criterion was found independent of the particulate contamination of oil; but depended on chemical degradation, being more sensitive for synthetic than mineral hydraulic oil. Total contamination index of the sensor depended on both the chemical degradation and particulate contamination of the oil; being most sensitive in blue wavelength, and least in the red. Test results for synthetic hydraulic oils monitored corroborated with results of other tests such as viscosity, total acid number, elemental optical emission spectroscopy, particulate counts and UV-VIS photospectrometry. Chromatic ratio showed a clearer indication of oil degradation, compared to key monitoring parameters such as total acid number, viscosity and particle counts. The results showed that these parameters are effective criteria for the condition monitoring of synthetic hydraulic oils.

• Journal of Hydrogen and New Energy
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• v.27 no.4
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• pp.378-385
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• 2016

In this study, we synthesized a biocatalyst consisting of glucose oxidase (GOx), polyethyleneimine (PEI) and carbon nanotube (CNT) with addition of glutaraldehyde (GA)(GA/[GOx/PEI/CNT])for fabrication of glucose sensor. Main bonding of the GA/[GOx/PEI/CNT] catalyst was formed by crosslinking of functional end groups between GOx/PEI and GA. Catalytic activity of GA/[GOx/PEI/CNT] was quantified by UV-Vis and electrochemical measurements. As a result of that, high immobilization ratio of 199% than other catalyst (with only physical adsorption) and large sensitivity value of $13.4{\mu}A/cm^2/mM$ was gained. With estimation of the biosensor stability, it was found that the GA/[GOx/PEI/CNT] kept about 88% of its initial activity even after three weeks. It shows GA minimized the loss of GOx and improved sensing ability and stability compared with that using other biocatalysts.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1159-1164
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• 2012

A new colorimetric sensors containing thiourea (1-(4-nitrophenyl)-3-quinolin-6-ylthiourea; 1) and urea(1-(4-nitrophenyl)-3-quinolin-6-ylurea; 2) moieties for fluoride were designed and synthesized. These simple receptors were characterized their stoichiometry, and investigates the mechanism of their selectivity as anion receptors. The addition of tetrabutylammonium fluoride salts to the solution of receptors caused a dramatically and clearly observable color changes from colorless to yellow. To examine their application as anion receptors by UV-vis and $^1H$ NMR spectroscopy results revealed their higher selectivity for fluoride ion than other anions. The receptors and fluoride ion formed a 1:1 stoichiometry complex through strong hydrogen bonding interactions in the first step, followed by a process of deprotonation in presence of an excess of $F^-$ in DMSO solvent.

• Advances in materials Research
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• v.2 no.4
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• pp.181-193
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• 2013

Description and theory of spin coating technique has been elaborately outlined and a spin coating machine designed and fabricated using affordable components. The system was easily built with interdisciplinary knowledge of mechanics, fluid mechanics and electronics. This equipment employs majorly three basic components and two circuit units in its operation. These include a high speed dc motor, a proximity sensor mounted at a distance of about 15 mm from a reflective metal attached to the spindle of the motor to detect every passage of the reflective metal at its front and generate pulses. The pulses are transmitted to a micro-controller which process them into rotational speed (revolution per minute) and displays it on a lead crystal display (LCD) which is also a component of the micro-controller. The circuit units are a dc power supply unit and a PWM motor speed controlling unit. The various components and circuit units of this equipment are housed in a metal casing made of an 18 gauge black metal sheet designed with a total area of 1, $529.2cm^2$. To illustrate the use of the spin-coating system, ZnO sol-gel films were prepared and characterized using SEM, XRD, UV-vis, FT-IR and RBS and the result agrees well with that obtained from standard equipment and a speed of up to 9000 RPM has been achieved.