• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.126.1-126.1
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• 2011

The SPICA (SPace Infrared Telescope for Cosmology & Astrophysics) project is a next-generation infrared space telescope optimized for mid- and far-infrared observation with a cryogenically cooled 3m-class telescope. Owing to unique capability of focal plane instruments onboard SPICA, it will enable us to resolve many astronomical key issues from the star-formation history of the universe to the planetary formation. The FPC (Focal Plane Camera) is a Korean-led near-infrared instrument as an international collaboration. Korean consortium for FPC proposed a key instrument responsible for a fine guiding (FPC-G). The back-up of FPC-G will make scientific observations as well. We have examined the legacy science programs for FPC and performed the feasibility study for the fine guiding system. Recently, the international review process is now in progress, in order to make a selection of the focal plane instruments. Here, we report the current status of SPICA/FPC project.

• ETRI Journal
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• v.34 no.4
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• pp.542-552
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• 2012

In this paper, a gaze estimation method is proposed for use with a large-sized display at a distance. Our research has the following four novelties: this is the first study on gaze-tracking for large-sized displays and large Z (viewing) distances; our gaze-tracking accuracy is not affected by head movements since the proposed method tracks the head by using a near infrared camera and an infrared light-emitting diode; the threshold for local binarization of the pupil area is adaptively determined by using a p-tile method based on circular edge detection irrespective of the eyelid or eyelash shadows; and accurate gaze position is calculated by using two support vector regressions without complicated calibrations for the camera, display, and user's eyes, in which the gaze positions and head movements are used as feature values. The root mean square error of gaze detection is calculated as $0.79^{\circ}$ for a 30-inch screen.

• Current Applied Physics
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• v.18 no.11
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• pp.1225-1229
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• 2018

In this paper, we investigated the electronic structures and defect states of $SrLaMgTaO_6$ (SLMTO) double perovskite structures by using resonant inelastic x-ray scattering. Recently, $Eu^{3+}$ doped SLMTO red phosphors have been vigorously investigated due to their higher red emission efficiency compared to commercial white light emitting diodes (W-LED). However, a comprehensive understanding on the electronic structures and defect states of host SLMTO compounds, which are specifically related to the W-LED and photoluminescence (PL), is far from complete. Here, we found that the PL spectra of SLMTO powder compounds sintered at a higher temperature, $1400^{\circ}C$, were weaker in the blue emission regions (at around 400 nm) and became enhanced in near infrared (NIR) regions compared to those sintered at $1200^{\circ}C$. To elucidate the difference of the PL spectra, we performed resonant inelastic x-ray spectroscopy (RIXS) at Ta L-edge. Our RIXS result implies that the microscopic origin of different PL spectra is not relevant to the Ta-related defects and oxygen vacancies.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2002.11a
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• pp.59-62
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• 2002

Wavelength selection and prediction algorithm for determining hematocrit are investigated. A model based on the difference in optical density induced by the pulsation of heart beat is developed by taking approximation of Twersky's theory on the assumption that the variation of blood vessel size is small during arterial pulsing[1]. A device is constructed with a five-wavelength LED array as light source. The selected wavelengths are two isobestic points and three in compensation for tissue scattering. Data are collected from 549 out-patients who are randomly grouped as calibration and prediction sets. The range of percent hematocrit was 19.3∼51.8. The ratio of the variations of optical density between systole and diastole at two different wavelengths is used as a variable. We selected several such variables that show high reproducibility among all variables. Multiple linear regression analysis is made. The relative percent error is 8% and the standard deviation is 3.67 for the calibration set. The relative % error and standard deviation of the prediction set are 8.2% and 3.69 respectively. We successfully demonstrate the possibility of non-invasive hematocrit measurement, particularly, using the wavelengths below 1000nm.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.3
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• pp.239-243
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• 2008

In this study, Bi-Sb thin film structure was prepared by thermal evaporation method. The electrical, optical transmission and structural characteristics of the prepared samples were introduced before and after thermal annealing process. At temperature of $500^{\circ}C$, the absorption of the structure was improved to reach 97% at near-infrared region. As well, the thermal annealing caused to reduce the bulk resistance of the Bi-Sb thin film structure. The morphology of Bi-Sb structure was also improved by thermal annealing as characteristic islands of the structure appear clearly in form hexagonal areas distinct from each other. This study is aiming to examine such structures if they are employed as photonic devices such as photodetectors, LED's and optical switches.

• Electronics and Telecommunications Trends
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• v.36 no.5
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• pp.1-8
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• 2021

Over the last three decades, the development of Ti:sapphire femtosecond lasers has led to advancements in scientific and industrial fields. In particular, these advanced lasers show great potential for applications with bio-imaging and medical surgery, such as two-photon microscopy, nonlinear Raman microscopy, optical coherence tomography, and ophthalmic surgery. Herein, we present a detailed description of the theoretical and experimental physics of Kerr-lens mode-locked femtosecond Ti:sapphire lasers and its two-photon microscopy.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.423-423
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• 2009

Currently, lasers are one of the most popular light sources in use for medical treatment. Many studies on low power lasers are being done in cell culture or through animal tests and most report different findings, making it difficult to verify their true effects. There are shifts in trends of studies from laser and LED that are expensive and generate heat problem to LED that are economically effective and safe. Its near infrared rays can penetrate deep into skin or muscle, up to 23 cm, without causing thermal damage or impairing neighboring tissues. This study verified the performance and effectiveness of an LED irradiator that was designed to emit similar wavelengths to that of a laser and thus could be used instead of a low level laser therapy in experiments on animals. And then, each experiment was performed to irradiation group and non-irradiation group for NTacSam:SD tissue cells. MIT assay method was chosen to verify the cell increase of two groups and the effect of irradiation on cell proliferation was examined by measuring 590nm transmittance of ELISA reader. As a result, the cell increase of NTacSam:SD tissue cells was verified in irradiation group as compared to non-irradiation group. The fact that specific wavelength irradiation has an effect on cell vitality and proliferation is known through this study.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.2
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• pp.165-171
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• 2022

The SiO₂/TiO₂ multilayer thin films used for narrow band pass filter were fabricated using E-beam evaporation method. The narrow band pass filter was used to enhance the resolution of spectroscopy and sensor applications with near infrared (NIR) light source. The narrow band pass filter with multilayer thin films were designed with Essential Macleod program. The multilayers of SiO₂/TiO₂ with 32 layers were deposited on the silicon encapsulation of IR with peak wavelength (λ_p) of 660 nm and NIR LEDs with λ_p of 830 nm, 880 nm, and 955 nm. After NIR light passed through the narrow band pass filter, the full width of half maximum of 33.4~48.6 nm became narrow to 20~24 nm owing to the absorption of photons with short or long wavelength of designed band of 20 nm. The SiO₂/TiO₂ band pass filter fabricated in this study can be used for sensor, optoelectronics, and NIR spectroscopy applications.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.6
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• pp.485-491
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• 2022

Intravenous injection is the most frequent invasive treatment for inpatients and is widely used for parenteral nutrition administration and blood products, and more than 1 billion procedures are used for peripheral catheter insertion, blood collection, and other IV therapy per year. Intravenous injection is one of the difficult procedures to be performed only by trained nurses with intravenous injection training, and failure can lead to thrombosis and hematoma or nerve damage to the vein. Accordingly, studies on auxiliary equipment capable of visualizing the vein structure of the back of the hand or arm are being published to reduce errors during intravenous injection. This study is a study on the performance difference according to the number of LEDs irradiating the 850nm wavelength band on a vein detector that visualizes the vein during intravenous injection. Four LED PCBs were produced by attaching NIR filters to CCD and CMOS camera lenses irradiated on the skin to acquire images, sharpen the acquired images using image processing algorithms, and project the sharpened images onto the skin. After that, each PCB was attached to the front end of the vein detector to detect the vein image and create a performance comparison questionnaire based on the vein image obtained for performance evaluation. The survey was conducted on 20 nurses working at K Hospital.