• Journal of the Korean Institute of Gas
• /
• v.12 no.2
• /
• pp.48-52
• /
• 2008

According to extremely industrial growth, gas facilities, equipments and chemical plants are gradually increased due to incremental demands of annual amount of gases. The safety management of gases, however, is still far from their requirements. Methane, the principal ingredient of natural gas, is inflammable and explosive and is much used in factories and houses. Therefore, these gas safety management is essential. So, we, with a program of the gas safety management, hope to develop the detection system of methane gas leak using mid-infrared ray LED and PD with $3.2\;{\mu}m$. The cryogenic cooling device is indispensible at laser but needless at LED driven on the room temperature if manufacturing optical sensor with $3.2\;{\mu}m$. It, consequently, is not only possible to implement for subminiature and portable type but also able to speedily detect methane of extremely small quantities because the $CH_4$ absorption intensity at $3.2\;{\mu}m$ is stronger than that at $1.67\;{\mu}m$. Our objective of research is to prevent gas leak accidents from occurring previously and to minimize the extent of damage from them.

• Korean Journal of Materials Research
• /
• v.27 no.6
• /
• pp.339-344
• /
• 2017

A series of $CaNb_2O_6:Dy^{3+}$, $CaNb_2O_6$:$Eu^{3+}$ and $CaNb_2O_6:Dy^{3+}$, $Eu^{3+}$ phosphors were prepared by solid-state reaction process. The effects of activator ions on the structural, morphological and optical properties of the phosphor particles were investigated. XRD patterns showed that all the phosphors had an orthorhombic system with a main (131) diffraction peak. For the $Dy^{3+}$-doped $CaNb_2O_6$ phosphor powders, the excitation spectra consisted of one broad band centered at 267 nm in the range of 210-310 nm and three weak peaks; the main emission band showed an intense yellow band at 575 nm that corresponded to the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transition of $Dy^{3+}$ ions. For the $Eu^{3+}$-doped $CaNb_2O_6$ phosphor, the emission spectra under ultraviolet excitation at 263 nm exhibited one strong reddish-orange band centered at 612 nm and four weak bands at 536, 593, 650, and 705 nm. For the $Dy^{3+}$ and $Eu^{3+}$-codoped $CaNb_2O_6$ phosphor powders, blue and yellow emission bands due to the $^4F_{9/2}{\rightarrow}^6H_{15/2}$ and $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transitions of $Dy^{3+}$ ions and a main reddish-orange emission line at 612 nm resulting from the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ ions were observed. As the concentration of $Eu^{3+}$ ions increased from 1 mol% to 10 mol%, the intensities of the emissions due to $Dy^{3+}$ ions rapidly decreased, while those of the emission bands originating from the $Eu^{3+}$ ions gradually increased, reached maxima at 10 mol%, and then slightly decreased at 15 mol% of $Eu^{3+}$. These results indicate that white light emission can be achieved by modulating the concentrations of the $Eu^{3+}$ ions incorporated into the $Dy^{3+}$-doped $CaNb_2O_6$ host lattice.

• Korean Journal of Optics and Photonics
• /
• v.9 no.4
• /
• pp.221-226
• /
• 1998

Ternary heavy metal oxide glasses in the $PbO-Bi_2O_3-Ga_2O_3$ system doped with $Er_2O_3$ were prepared and their spectroscopic properties, such as radiative transition probability, calculated and measured radiative lifetimes and cross-sections of 1.5 $\mu\textrm{m}$ and 2.7 $\mu\textrm{m}$ emissions were analyzed. Enhanced quantum efficiencies of some electronic transitions were evident mainly because of the low vibrational phonon energy ($~500cm^{-1}$) inherent in the host glasses. This seems to be the main reason for obtaining the 2.7 $\mu\textrm{m}$ luminescence which is normally quenched in the conventional oxide glasses. In addition, green and red fluorescence emissions were observed through the frequency upconversion processes of the 798 nm excitation. Non-radiative transition due to the multiphonon relaxation is a dominant lifetime-shortening mechanism in the 4f-4f transitions in $Er^{3+}$ ion except for the $^4S_{3/2}{\rightarrow}^4I_{15/2}$ transition where a non-radiative transfer to band-gap excitation of the host glasses is dominant. Melting of glasses under an inert gas atmosphere and (or) addition of the typical glass-network former into glasses is necessary in order to enhance the quantum efficiency of the transition.

• KIPS Transactions on Computer and Communication Systems
• /
• v.3 no.10
• /
• pp.383-392
• /
• 2014

The research for coatings is one of the most popular and active research in the polymer industry. For the coatings, electronics industry, medical and optical fields are growing more important. In particular, the trend is the increasing of the technical requirements for the performance and accuracy of the coatings by the development of automotive and electronic parts. In addition, the industry has a need of more intelligent and automated system in the industry is increasing by introduction of the IoT and big data analysis based on the environmental information and the context information. In this paper, we propose an optimization model for the design of experiments based coating formulation data objects using the Internet technologies and big data analytics. In this paper, the coating formulation was calculated based on the best data analysis is based on the experimental design, modify the operator with respect to the error caused based on the coating formulation used in the actual production site data and the corrected result data. Further optimization model to correct the reference value by leveraging big data analysis and Internet of things technology only existing coating formulation is applied as the reference data using a manufacturing environment and context information retrieval in color and quality, the most important factor in maintaining and was derived. Based on data obtained from an experiment and analysis is improving the accuracy of the combination data and making it possible to give a LOT shorter working hours per data. Also the data shortens the production time due to the reduction in the delivery time per treatment and It can contribute to cost reduction or the like defect rate reduced. Further, it is possible to obtain a standard data in the manufacturing process for the various models.

• Korean Journal of Remote Sensing
• /
• v.24 no.6
• /
• pp.605-612
• /
• 2008

In this study, we estimate solar surface insolation (SSI) by using physical methods with MTSAT-1R data. SSI is regarded as crucial parameter when interpreting solar-earth energy system, climate change, and agricultural production predict application. Most of SSI estimation model mainly uses ground based-measurement such as pyranometer to tune the constructed model and to validate retrieved SSI data from optical channels. When compared estimated SSI with pyranometer measurements, there are some systemic differences between those instruments. The pyranometer data observed upward-looking hemispherical solid angle and distributed hourly measurements data which are averaged every 2 minute instantaneous observation. Whereas MTSAT-1R channels data are taken instantaneously images at fixed measurement time over scan area, and are pixel-based observation with a much smaller solid angle view. Those temporal discrepancies result from systemic differences can induce validation error. In this study, we adjust hour when estimate SSI to improve the retrieved accurate SSI.

• Korean Journal of Remote Sensing
• /
• v.18 no.4
• /
• pp.209-220
• /
• 2002

We carried out studies on SAR image intensity and interferometric phase over oyster sea farms. Strong backscattering was observed in amplitude images, and that was considered as a radar signal double bouncing from horizontal bars. These sea farming structures are not visible in satellite optical images except IKONOS image, so that it demonstrates the value of radar remote sensing as an effective tool in support of sea farm detection. The intensity of the image is sensitive to system parameters including wavelength, polarization, and look direction, but does not correlate to tide height. We found that the strongest backscattering can be obtained by L-band HH-polarization with a look direction perpendicular to the horizontal bar. We also succeeded in generating 21 coherent JERS-1 SAR interferometric pairs over the oyster farms. The general trend of the fringe rate of the interferometric phases appeared to be governed by altitude of ambiguity. The general trend was modeled by an inverse function and removed to have a residual phase. The residual phase showed a linear relation with the tide height. The results demonstrate for the first time that SAR can possibly be used to estimate sea level. However, the r.m.s. error of a regression line is 11.7 cm, and that is so far too large to make reliable assessments of sea level in practical applications. Further studies is required to improve the accuracy specifically using multi-polarization SAR data.

• Korean Journal of Remote Sensing
• /
• v.24 no.4
• /
• pp.369-379
• /
• 2008

The aerosol retrieval algorithm for the Moderate Resolution Imaging Spectroradiometer (MODIS) measurements was updated recently. This paper reports on the comparison and validation of two latest versions (Collection 4 and 5, shortly C004 and C005) of the MODIS aerosol product over northeast Asian region. The differences between the aerosol optical thickness (AOT) from the C004 and C005 retrieval algorithms and the correlation with ground based AERONET sunphotometer observations are investigated. Over the study region, spatially averaged annual mean AOT retrieved from C005 algorithm $(AOT_{C005})$ is about 0.035 AOT (5%) less than the C004 counterparts. The linear correlations between MODIS and AERONET AOT also are R=0.89 (slope=0.86) for the C004 and R=0.95 (slope=1.00) for the C005. Moreover, the magnitude of the mean error in $AOT_{C005}$, difference between MODIS AOT and AERONET AOT, is 40% less than that in $AOT_{C004}$.

• Korean Journal of Optics and Photonics
• /
• v.21 no.3
• /
• pp.123-128
• /
• 2010

Sum frequency generation was utilized to obtain a yellow laser with the wavelength of 578.4 nm for a probe laser of an Yb lattice clock. The output of an Nd:YAG laser with wavelength of 1319 nm and that of an Yb-fiber laser with wavelength of 1030 nm were passed through a waveguided periodically-poled lithium niobate (WG-PPLN) for sum frequency generation. It is required that the probe laser has a linewidth of the order of 1 Hz to fully resolve the Yb lattice clock transition. Thus, the linewidth of the probe laser was reduced by stabilizing the frequency to a super-cavity. This was made of ULE with a low thermal expansion coefficient, and was mounted on an active vibration-isolation table at the optimal point for the reduced sensitivity to vibration. Also, this was installed in a vacuum chamber, and the temperature was stabilized to 1 mK level. This system was installed in an acoustic enclosure to block acoustic noise. The finesse of the super-cavity was measured to be 380 000 from the photon life time of the cavity.

• Korean Journal of Applied Biomechanics
• /
• v.31 no.4
• /
• pp.276-282
• /
• 2021

Objective: To investigate effects of Fibular Repositioning Taping (FRT) on lower extremity joint stiffness and angle during drop-landing. Method: Twenty-eight participants (14 healthy, 14 with chronic ankle instability [CAI]) performed drop-landings from a 60 cm box; three were performed prior to tape application and three were performed post-FRT. Three-dimensional kinematic and kinetic data were collected using an infrared optical camera system (Vicon Motion Systems Ltd. Oxford, UK) and force-plate (AMTI, Watertown, MA). Joint stiffness and sagittal angle of the ankle, knee, and hip were analyzed. Results: The hip [Healthy: p<.05; M ± SD: 29.43 ± 11.27 (pre), 33.04 ± 12.03 (post); CAI: p<.05; M ± SD: 31.45 ± 9.70 (pre), 32.29 ± 9.85 (post)] and knee [Healthy: p<.05; M ± SD: 53.44 ± 8.09 (pre), 55.13 ± 8.36 (post); CAI: p<.05; M ± SD: 53.12 ± 8.35 (pre), 55.55 ± 9.81 (post)] joints demonstrated significant increases in sagittal angle after FRT. A significant decrease in joint angle was found at the ankle [Healthy: p<.05; M ± SD: 56.10 ± 3.71 (pre), 54.09 ± 4.31 (post); CAI: p<.05; M ± SD: 52.80 ± 6.04 (pre), 49.86 ± 10.08 (post)]. A significant decrease in hip [Healthy: p<.05; M ± SD: 1549.16 ± 517.53 (pre), 1272.48 ± 646.73 (post); CAI: p<.05; M ± SD: 1300.42 ± 595.55 (pre), 1158.27 ± 550.58 (post)] and knee [Healthy: p<.05; M ± SD: 270.12 ± 54.07 (pre), 239.13 ± 64.70 (post); CAI: p<.05; M ± SD: 241.58 ± 93.48 (pre), 214.63 ± 101.00 (post)] joint stiffness was found post-FRT application, while no difference was found at the ankle [Healthy: p>.05; M ± SD: 57.29 ± 17.04 (pre), 59.37 ± 18.30 (post); CAI: p>.05; M ± SD: 69.15 ± 17.63 (pre), 77.24 ± 35.05 (post)]. Conclusion FRT application decreased joint angle at the ankle without altering ankle joint stiffness. In contrast, decreased joint stiffness and increased joint angle was found at the hip and knee following FRT. Thus, participants utilize an altered shock absorption mechanism during drop-landings following FRT. When compared to previous research, the joint kinematics and stiffness of the lower extremity appear to be different following FRT versus traditional ankle taping.

• Korean Journal of Remote Sensing
• /
• v.37 no.5_1
• /
• pp.1013-1027
• /
• 2021

Images taken with KOMPSAT-3 have additional NIR and PAN bands, as well as RGB regions of the visible ray band, compared to imagestaken with a standard camera. Furthermore, electrical and optical properties must be considered because a wide radius area of approximately 17 km or more is photographed at an altitude of 685 km above the ground. In other words, the camera sensor of KOMPSAT-3 is distorted by each CCD pixel, characteristics of each band,sensitivity and time-dependent change, CCD geometry. In order to solve the distortion, correction of the sensors is essential. In this paper, we propose a method for detecting uniform regions in side-slider-based KOMPSAT-3 images using segment-based noise analysis. After detecting a uniform area with the corresponding algorithm, a correction table was created for each sensor to apply the non-uniformity correction algorithm, and satellite image correction was performed using the created correction table. As a result, the proposed method reduced the distortion of the satellite image,such as vertical noise, compared to the conventional method. The relative radiation accuracy index, which is an index based on mean square error (RA) and an index based on absolute error (RE), wasfound to have a comparative advantage of 0.3 percent and 0.15 percent, respectively, over the conventional method.