• Analytical Science and Technology
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• v.13 no.5
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• pp.608-615
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• 2000

A determination method of trace nickel and cobalt in water samples was studied and developed by adsorbing their complexes on ion exchange resin suspension. The analytical ions were formed as complexes with a ligand of APDC (ammonium pyrrolidinedithiocarbamate) and adsorbed on anion exchange resin of Dowex 2-X8. After the suspension was filtered out with membrane filter, the complexes were dissolved in HCl solution by an ultrasonic vibrator for ET-AAS determination. Several conditions were optimized as followings. pH of sample solution: 5.0, amount of ligand APDC: more than 430 times in mole ratio, the type and concentration of acid: 0.1 M HCl, and vibration time: 7 minutes. The addition of palladium in the HCl solution could improve the reproducibility and sensitivity by a matrix modification in the absorbance measurement. This procedure was applied for the analysis of three kinds of real water samples. The detection limits equivalent to 3 times standard deviation of blank were Co 0.36 ng/mL and Ni 0.27 ng/mL and recoveries in spiked samples were 99-102% for cobalt and 100-105% for nickel.

• Korean Journal of Optics and Photonics
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• v.22 no.4
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• pp.191-197
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• 2011

In this paper, we have designed an integrated triplexer which is the basic component for a FTTH(Fiber To The Home) system which can transmit CATV and voice/data at the same time in a single fiber. The integrated triplexer can be fabricated with a novel technique of "Micro-Block Stacking (MBS)" method which automatically aligns the optical components in the optical beam pass using accurate ceramic holders. We analyze the displacement of the optical focus according to the tolerances of the component dimensions and the assembly process using code V simulator. For the transmitter, the most serious shift of the focal points is caused by the displacements of the LD spot. So the focal point moves up to $72{\mu}m$ from the center point for ${\pm}25{\mu}m$, ${\pm}25{\mu}m$, ${\pm}30{\mu}m$ displacements. For the receiver the most serious shift of the focal points is caused by the displacements of a 0.8mm ball lens (for the analog receiving part) and a micro ball lens (for the digital receiving part), and the focal point moves up to $55{\mu}$ for ${\pm}55{\mu}m$, ${\pm}5{\mu}m$, ${\pm}55{\mu}m$ micro ball lens displacements.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.507-513
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• 2006

In this paper, we propose an improved image encryption and fault-tolerance decryption method using phase wrapping and phase encoding in the frequency domain. To generate an encrypted image, an encrypting key which denotes the product of a phase-encoded virtual image, not an original image, and a random phase image is zero-padded and Fourier transformed and its real-valued data is phase-encoded. The decryption process is simply performed by performing the inverse Fourier transform for multiplication of the encrypted key with the decrypting key, made of the proposed phase wrapping method, in the output plane with a spatial filter. This process has the advantages of solving optical alignment and pixel-to-pixel mapping problems. The proposed method using the virtual image, which does not contain any information from the original image, prevents the possibility of counterfeiting from unauthorized people and also can be used as a current spatial light modulator technology by phase encoding of the real-valued data. Computer simulations show the validity of the encryption scheme and the robustness to noise of the encrypted key or the decryption key in the proposed technique.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.326-333
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• 2005

Phase-only encryption scheme using exclusive-OR rules in Fourier plane and a single path decryption system are presented. A zero-padded original image, multiplied by a random phase image, is Fourier transformed and its real-valued data is encrypted with key data by using XOR rules. A decryption is simply performed based on 2-1 setup with spatial filter by Fourier transform for multiplying phase-only encrypted data by phase-only key data, which are obtained by phase-encoding process, and spatial filtering for zero-order elimination in inverse-Fourier plane. Since the encryption process is peformed in Fourier plane, proposed encryption scheme is more tolerant to loss of key information by scratching or cutting than previous XOR encryption method in space domain. Compare with previous phase-visualization systems, due to the simple architecture without a reference wave, our system is basically robust to mechanical vibrations and fluctuations. Numerical simulations have confirmed the proposed technique as high-level encryption and simple decryption architecture.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.6
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• pp.781-787
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• 2014

The dimensionless extinction constants of particulate matter for F-76 diesel and JP-8 aviation fuels were measured at both 633 nm and 853 nm in the transmission cell where the simultaneous gravimetric measurement of PM concentration is compared to the light extinction measurement. For the F-76 diesel PM, the average value of the dimensionless extinction constants at 633 nm was 8.8 whereas that of the dimensionless extinction constants for JP-8 was 9.8 at the same wavelength. As the wavelength is increased to 853 nm, the average value for the F-76 diesel was reduced to 8.2 whereas that for JP-8 was decreased to 8.9.

• Korean Journal of Remote Sensing
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• v.37 no.5_2
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• pp.1235-1243
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• 2021

Geostationary Ocean Color Imager 2 (GOCI-II) on Geo-KOMPSAT-2 (GK2B)satellite was developed as a mission successor of GOCI on COMS which had been operated for around 10 years since launch in 2010 to observe and monitor ocean color around Korean peninsula. GOCI-II on GK2B was successfully launched in February of 2020 to continue for detection, monitoring, quantification, and prediction of short/long term changes of coastal ocean environment for marine science research and application purpose. GOCI-II had already finished IAC and IOT including early in-orbit calibration and had been handed over to NOSC (National Ocean Satellite Center) in KHOA (Korea Hydrographic and Oceanographic Agency). Radiometric calibration was periodically conducted using on-board solar calibration system in GOCI-II. The final calibrated gain and offset were applied and validated during IOT. And three video parameter sets for one day and 12 video parameter sets for a year was selected and transferred to NOSC for normal operation. Star measurement-based INR (Image Navigation and Registration) navigation filtering and landmark measurement-based image geometric correction were applied to meet the all INR requirements. The GOCI2 INR software was validated through INR IOT. In this paper, status and results of IOT, radiometric calibration and INR of GOCI-II are analysed and described.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.278-280
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• 2019

Flow cytometer is one of the instrument that can measure various optical properties of a single cell or microparticle. These parameters including size, granularity, and fluorescence intensity are determined by the physical and optical interaction of the cells with excitation light source. However, users have some difficulties such as high cost, size of instrument, and limited fluorescence selectivity. In addition, abundant data is also unintentionally acquired even though user wants to have a single optical parameter. For these reasons, the use of flow cytometer is more challenging for researchers to apply their study. Therefore, the proposed study aims to develop a low-cost portable fluorescence acquisition system using a commercially available light-emitting diode and photodiode. It is designed by a 3D printer, and fluorescence selectivities are increased by changing of the light source / optical filter / detection sensor. Various number sets of fluorescently labeled cells were measured, and its feasibility was evaluated through the proposed system. As a result, acquried fluorescence intensities were proportional to the concentration of the cells and showed high linearity.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.6
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• pp.463-470
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• 2022

Intravenous injection is widely used for patient treatment, including injection drugs, fluids, parenteral nutrition, and blood products, and is the most frequently performed invasive treatment for inpatients, including blood collection, peripheral catheter insertion, and other IV therapy, and more than 1 billion cases per year. Intravenous injection is one of the difficult procedures performed only by experienced nurses who have been trained in intravenous injection, and failure can lead to thrombosis and hematoma or nerve damage to the vein. Nurses who frequently perform intravenous injections may also make mistakes because it is not easy to detect veins due to factors such as obesity, skin color, and age. Accordingly, studies on auxiliary equipment capable of visualizing the venous structure of the back of the hand or arm have been published to reduce mistakes during intravenous injection. This paper is about the development of venous detection equipment that visualizes venous structure during intravenous injection, and the optimal combination was selected by comparing the brightness of acquired images according to the combination of near-infrared (NIR) LED and Filter with different wavelength bands. In addition, an image processing algorithm was derived to threshehold and making blood vessel part to green through grayscale conversion, histogram equilzation, and sharpening filters for clarity of vein images obtained through the implemented venous detection experimental module.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.4
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• pp.304-309
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• 2015

To evaluate the degree of contamination caused by oil spill accident in the sea, the in-situ sensors which are based on the scientific method are needed in the real site. The sensors which are based on the fluorescence detection theory can provide the useful data, such as the concentration of oil. However these kinds of sensors commonly are composed of the ultraviolet (UV) light source such as UV mercury lamp, the multiple excitation/emission filters and the optical sensor which is mainly photomultiplier tube (PMT) type. Therefore, the size of the total sensing platform is large not suitable to be handled in the oil spill field and also the total price of it is extremely expensive. To overcome these drawbacks, we designed the fluorimeter for the oil spill detection which has compact size and cost effectiveness. Before the detail design process, we conducted the experiments to measure the excitation and emission spectrum of oils using five different kinds of crude oils and three different kinds of processed oils. And the fluorescence spectrometer were used to analyze the excitation and emission spectrum of oil samples. We have compared the spectrum results and drawn the each common spectrum regions of excitation and emission. In the experiments, we can see that the average gap between maximum excitation and emission peak wavelengths is near 50 nm for the every case. In the experiment which were fixed by the excitation wavelength of 365 nm and 405 nm, we can find out that the intensity of emission was weaker than that of 280 nm and 325 nm. So, if the light sources having the wavelength of 365 nm or 405 nm are used in the design process of fluorimeter, the optical sensor needs to have the sensitivity which can cover the weak light intensity. Through the results which were derived by the experiment, we can define the important factors which can be useful to select the effective wavelengths of light source, photo detector and filters.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.275-281
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• 2018

It is known that he pollutant emitted from the combustion process of marine fuel oil causes air pollution and harmful effects to the human body. Accordingly, IMO regulates pollutants emitted from ships. However, the regulation of Particulate Matter (PM) is still in the process of debate, so preemptive action is needed. Fundamental research on PM is essential. In this study, the Dimensionless Light Extinction Constant ($K_e$) of fuel oil used in marine diesel engines was measured and analyzed to construct the basic data of the PM generated from marine-based fuel oil. The fuel oil used in the land diesel engine was measured in the same way for character comparison. Both fuel oils differ in sulfur content and density. The $K_e$ was measured via the optical method using a 633 nm laser and was determined by using the volume fraction of PM collected by the gravimetric filter method. The $K_e$ of the PM discharged from marine fuel oil is 8.28, and the land fuel oil is 8.44. The $K_e$ of two fuel oils was similar within the measurement uncertainty range. However, it was found by comparison with the value obtained by the Rayleigh-Limit solution that the light scattering portion could be large. Also, it was found that light extinction characteristics could be different due to the relationship between light transmittance and collected mass.