• Korean Journal of Remote Sensing
• /
• v.36 no.2_1
• /
• pp.167-178
• /
• 2020

KOMPSAT-3A images have been used in various kinds of applications, since its launch in 2015. However, there were limits to scientific analysis and application extensions of these data, such as vegetation index estimation, because no tool was developed to obtain the surface reflectance required for analysis of the actual land environment. The surface reflectance is a product of performing an absolute atmospheric correction or calibration. The objective of this study is to quantitatively verify the accuracy of top-of-atmosphere reflectance and surface reflectance of KOMPSAT-3A images produced from the OTB open-source extension program, performing the cross-validation with those provided by a site measurement data of RadCalNet, an international Calibration/Validation (Cal/Val) portal. Besides, surface reflectance was obtained from Landsat-8 OLI images in the same site and applied together to the cross-validation process. According to the experiment, it is proven that the top-of-atmosphere reflectance of KOMPSAT-3A images differs by up to ± 0.02 in the range of 0.00 to 1.00 compared to the mean value of the RadCalNet data corresponding to the same spectral band. Surface reflectance in KOMPSAT-3A images also showed a high degree of consistency with RadCalNet data representing the difference of 0.02 to 0.04. These results are expected to be applicable to generate the value-added products of KOMPSAT-3A images as analysisready data (ARD). The tools applied in thisstudy and the research scheme can be extended as the new implementation of each sensor model to new types of multispectral images of compact advanced satellites (CAS) for land, agriculture, and forestry and the verification method, respectively.

• Korean Journal of Remote Sensing
• /
• v.36 no.5_1
• /
• pp.735-747
• /
• 2020

Recent advanced UAV (Unmanned Aerial Vehicle) technology supply new opportunities for estimating crop condition using high resolution imagery. We analyzed the diurnal change of reflectance and NDVI (Normalized Difference Vegetation Index) in UAV imagery for crop monitoring in clear day condition. Multi-spectral images were obtained from a 5-band multi-spectral camera mounted on rotary wing UAV. Reflectance were derived by the direct method using down-welling irradiance measurement. Reflectance using UAV imagery on calibration tarp, concrete and crop experimental sites did not show stable by time and daily reproducible values. But the CV (Coefficient of Variation) of diurnal NDVI on crop experimental sites was less than 5%. As a result of comparing NDVI at the similar time for two day, the daily mean average ratio of error showed a difference of 0.62 to 3.97%. Therefore, it is considered that NDVI using UAV imagery can be used for time series crop monitoring.

• Science of Emotion and Sensibility
• /
• v.14 no.2
• /
• pp.311-320
• /
• 2011

To quantitatively analyze the effects of color stimulation which is one of the major affecting factors on human emotion, we studied the relationship between color preference and the Electroencephalography (EEG) to 3 color stimuli; bright yellow red (BYR), deep green yellow (DGY), and vivid blue (VB). Physiological signal measured by EEG on the color stimulation was closely related with their well-known colorful images. The brain become more activated with decreasing the color temperature (BYR${\geq}$DGY>VB), and the right brain is more sensitive than the left. On the whole, the EEG values of the frequency bands are in order to beta ${\geq}$ theta and alpha > gamma. As decreasing the color temperature, beta wave increased (BYR${\geq}$DGY>VB), and alpha, beta and gamma waves increased with increasing the color temperature (BYR${\geq}$DGY>VB). The relationship between the color preference and EEG values showed EEG gets more activated at some frequency bands when the color preference becomes higher. In conclusion, the specific frequency band could be activating by a color stimuli which had showed higher the preference. It means that these color stimuli can apply for various industries such as beauty industry, interior design, fashion design, color therapy, and etc.

• Journal of Broadcast Engineering
• /
• v.18 no.4
• /
• pp.572-588
• /
• 2013

In this paper, 4K-UHDTV or 8K-UHDTV and UHD-3DTV that the next generation broadcasting implementation and the possibility of direct receiving environment construction is analyzed on the terrestrial broadcasting. Particularly, we investigated the possibility by analyzing the previous and related works with regard to UHDTV transmission by DVB-T2 that is one of the best commercialized transmission mode. In order that the UHDTV broadcasting succeeds once again after completion of digital terrestrial switch over at the end of 2012, the ultra high resolution image transfer is important. However, the direct, the indoor and ubiquitous receiving environment is important in not only TV but also the personal type multimedia terminal in the sense of UHDTV service penetration. Therefore, in this paper, by using SFN and high error-correcting mode in DVB-T2 standard, the efficient frequency utilization and effective reception environment construction is illustrated. Particularly, SFN network constitution by 2 mutually different frequencies including the VHF bandwidth and UHF band, and etc. is shown. And the method that builds the free wireless receive environment by using SFN low power radio repeater and for home use gap filler is proposed. And the effect and frequency amount required are presented, when UHDTV broadcasting use 10MHz bandwidth.

• Journal of Bio-Environment Control
• /
• v.23 no.1
• /
• pp.50-55
• /
• 2014

This study was conducted to investigate the responses of red pepper (Hongjinju) leaves under water stress. Hyperspectral short wave infrared (SWIR, 1000~1800 nm) reflectance imaging techniques were used to acquire the spectral images for the red pepper leaves with and without water stress. The acquired spectral data were analyzed with a multivariate analysis method of ANOVA (analysis of variance). The ANOVA model suggested that 1449 nm wavebands was the most effective to determine the stress responses of the red pepper leaves exposed to the water deficiency. The waveband of 1449 nm was closely related to the water absorption band. The processed spectral image of 1449 nm could separate the non-stress, moderate stress (-20 kPa), and severe stress (-50 kPa) groups of red pepper leaves distinctively. Results demonstrated that hyperspectral imaging technique can be applied to monitoring the stress responses of red pepper leaves which are an indicator of physiological and biochemical changes under water deficiency.

• Journal of the Korean Society of Radiology
• /
• v.9 no.5
• /
• pp.307-314
• /
• 2015

This study was conducted in reducing the involuntary motion artifacts because of lungs and heart movements as well as the aliasing artifacts generated during the use of the reduced-FOV EPI technique while performing breast MRI. Performed on a total of 38 obesity female subjects who visited the clinic for pre-examination before surgery within the period from August 1 to November 30, 2014. The 3.0T MRI scanner equipped with a breast scanning coil. Qualitative and quantitative analyses were each used for the evaluation of the acquired images while an Paired T-test and Wilcoxon rank test were performed to check the statistical significance. The variation ratio rose by 15.69% with the additional application of a pre-saturation pulse in the lesion, by 13.72% near the lesion, and 20.63% in the fat and the contrast-to-noise ratio rose by 10.58% in and near the lesion and by 12.03% in the lesion and fat, respectively. there were increases of 22.05% and 21.42% at 0 and 1000 respectively in qulitative evaluation and growth of 16.10% in apparent diffusion coefficient. it showed a statistically significant result(p<0.05) in signal to noise ratio, contrast to noise ratio, diffusion slope coefficient and apparent diffusion coefficient. The involuntary movements artifacts that occur in the phase encoding direction and the aliasing artifacts are considered to be reduced to obtain the best image in the additional use of the pre-saturation pulse as DWI is acquired.

• Composites Research
• /
• v.30 no.6
• /
• pp.356-364
• /
• 2017

Composite lattice structures are tried to be used in various fields because of its benefit in physical properties. With increase of demand of the composite lattice structure, nondestructive testing technology is also required to certificate the quality of the manufactured structures. Recently, research on the development of the composite lattice structure in Republic of Korea was started and accordingly, fast and accurate non-destructive evaluation technology was needed to finalize the manufacturing process. This paper studied non-destructive testing methods for composite lattice structure using laser ultrasonic propagation imaging systems. Pulse-echo ultrasonic propagation imaging system was able to inspect a rib structure wrapped with a skin structure. To reduce the time of inspection, a band divider, which can get signal in different frequency bands at once, was developed. Its performance was proved in an aluminum sandwich panel. In addition, to increase a quality of results, curvature compensating algorithm was developed. On the other hand, guided wave ultrasonic propagation imaging system was applied to inspect delamination in a rib structure. To increase an area of inspection, multi-source ultrasonic wave propagation image was applied, and defects were successfully highlighted with variable time window amplitude mapping algorithm. These imply that ultrasonic propagation imaging systems provides fast and accurate non-destructive testing results for composite lattice structure in a stage of the manufacturing process.

• The Korean Journal of Pain
• /
• v.8 no.2
• /
• pp.298-303
• /
• 1995

We have inserted epidural catheter for single or continuous injection of a drug for epidural analgesia. It is important to localize the tip of epidural catheter in appropriate site to acquire the most effective analgesia. In epidural block, we observed course and location of the tip of epidural catheter. Subject: 70 patients were divided into group I(non-injection of saline group during catheter insertion) and group II(injection group during catheter insertion). Group I included cervical(n=20), thoracic(n=10), and lumbar(n=20) epidural group. Group II, cervical(n=10), and lumbar(n=10) epidural group. Method: 19G FlexTip $Plus^{TM}$ Epidural Catheter ($Arrow^{(R)}$) was inserted 10cm cephaladly in epidural space with(group II) or without(group I) saline flushing. We observed course and location of the tip of epidural catheter by C-arm image intensifier during injection of contrast media ($Omnipaque^{(R)}$). Result: In group I, the number of tips of epidural catheters located within 2 cm from inserted site were: cervical 14/20(70%), thoracic 2/10(20%). lumbar 16/20(80%). In thoracic epidural blocks, tips of epidural catheters were more cephaladly located than with cervical and lumbar epidural blocks. With cervical epidural blocks, the number of tips of epidural catheters located within 2 cm from insertion site were less in group II than group I (20% vs. 70%). But no significant differences were noted between group I and group II with lumbar epidural block(90% vs. 80%). The number of tips of epidural catheters located around a predicted site were: cervical 2/20(10%), thoracic 4/10(40%), lumbar 0/20(0%) in group I, and cervical 2/10(20%), lumbar 1/10(10%) in group II. Conclusion: It was impossible to predict the exact location of tips of epidural catheters by measuring the inserted length without epidurogram. With many cases, tips of epidural catheters were located around the insertion site in lumbar epidural blocks, and in some cases around the predicted site in thoracic epidural blocks. The results suggests that epidural block should be done at a point near the required band of analgesia.

• Journal of the Korean Chemical Society
• /
• v.37 no.6
• /
• pp.570-576
• /
• 1993

1-, 3-, 9-, and 21-Monolayer Langmuir-Blodgett(LB) films of stearic acid were deposited on silver-coated glass slides at the surface pressure of 30 mN/m. Fourier transform infrared(FTIR) reflection-absorption spectra (RAS) of these LB films were recorded at various temperatures from 31 to $72^{\circ}C.$ The spectra at $31^{\circ}C$ exhibited characteristic features of highly perpendicular orientation of the hydrocarbon chain. In the 1-monolayer LB film, the C=O stretching band was not observed, presumably due to the image dipole effect on the silver surface. In the 1-and 3-monolayer LB films, the trans isomer of stearic acid was prominent, but the cis isomer was dominant in the 21-monolayer LB film. FTIR-RAS measurements at an elevated temperature indicated that the chain melting temperature increases and approached to the bulk melting point with increasing the number of monolayer, except for the 1-monolayer LB film which has a higher melting temperature than the 3-monolayer film due to the strong interaction with the silver substrate.

• Korean Journal of Remote Sensing
• /
• v.15 no.3
• /
• pp.227-238
• /
• 1999

In advance of launch, simulated radiances of the Ocean Scanning Multispectral Imager (OSMI) will be very useful to guess the real imagery of OSMI and to prepare for data processing of OSMI. The data processing system for OSMI which is one of sensors aboard Korea Multi-Purpose Satellite (KOMPSAT) scheduled for launch in 1999 is developed based on the SeaWiFS Data Analysis System (SeaDAS). Simulation of radiances requires information on the spectral band, orbital and scanning characteristics of the OSMI and KOMPSAT spacecraft. This paper also describes a method to create simulated radiances of the OSMI over the oceans. Our method for constructing a simulated OSMI imagery is to propagate a KOMPSAT orbit over a field of Coastal Zone Color Scanner (CZCS) pigment concentrations and to use the values and atmospheric components for calculation of total radiances. A modified Brouwer-Lyddane model with drag was used for the realistic orbit prediction, the CZCS pigment concentrations were used to compute water-leaving radiances, and a variety of radiative transfer models were used to calculate atmospheric contributions to total radiances detected by OSMI. Imagery of the simulated OSMI radiances for 412, 443, 490, 555, 765, 865nm was obtained. As expected, water-leaving radiances were only a small fraction (below 10%) of total radiances and sun glint contaminations were observed near the solar declination. Therefore, atmospheric correction is critical in the calculation of pigment concentration from total radiances. Because the imagery near the sun's glitter pattern is virtually useless and must be discarded, more advanced data collection planning will be required to succeed in the mission of OSMI which is consistent monitoring of global oceans during three year mission lifetime.