• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1526-1526
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• 2001

To improve the accuracy of sweetness sensor in automated sorting operations, it is necessary to clarify unevenness of the sugar content distribution within fruits. And it is expected that the technique to evaluate the content distribution in fruits contribute to the development of the near-infrared (NIR) imaging spectroscopy. Sugiyama (1999) had succeeded to visualize the distribution of the sugar content on the surface of a half-cut green fresh melon. However, this method cannot be applied to red flesh melons because it depends on information of the absorption band of chlorophyll (676 nm), which is affected by the color of the fresh. The objective of this study was to develop the universal visualization method depends on the absorption band of sugar, which can be applied to various kinds of melons and other fruits. The relationship between the sugar contents and absorption spectra of both green and red fresh melons were investigated by using a NIR spectrometer to determine the absorption band of sugar. The combination of 2$\^$nd/ derivative absorbances at 902 nm and 874 nm was highly correlated with the sugar contents. The wavelength of 902 nm is attributed to the absorption band of sugar. A cooled charge-coupled device (CCD) imaging camera which has 16 bit (65536 steps) A/D resolution was equipped with rotating band-pass filter wheel and used to capture the spectral absorption images of the flesh of a vertically half-cut red fresh melon. The advantage of the high A/D resolution in this research is that each pixel of the CCD is expected to function as a detector of the NIR spectrometer for quantitative analysis. Images at 846 nm, 874 nm, 902 nm and 930 nm were acquired using this CCD camera. Then the 2$\^$nd/ derivative absorbances at 902 nm and 874 nm at each pixel were calculated using these four images. On the other hand, parts of the same melon were extracted for capturing the images and squeezed for the measurement of sugar content. Then the calibration curve between the combination of 2$\^$nd/ derivative absorbances at 902 nm and 874 nm and sugar content was developed. The calibration method based on NIR spectroscopy techniques was applied to each pixel of the images to convert the 2$\^$nd/ derivative absorbances into the Brix sugar content. Mapping the sugar content value of each pixel with linear color scale, the distribution of the sugar content was visualized. As a result of the visualization, it was quantitatively confirmed that the Brix sugar contents are low at the near of the skin and become higher towards the seeds. This result suggests that the visualization technique by the NIR imaging spectroscopy could become a new useful method fer quality evaluation of melons.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.42-42
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• 2012

The First stars (Pop.III stars) in the universe are expected to be formed between the recombination era at z - 1100 and the most distant quasar (z - 8). They have never been directly detected due to its faintness so far, but can be observed as a background radiation at around 1${\mu}m$ which is called the Cosmic Near-Infrared Background (CNB). Main part of the CNB is thought to be redshifted Lyman-alpha from gas clouds surrounding the Pop.III stars. Until now, the COBE (COsmic Background Explorer) and the IRTS (Infrared Telescope in Space) observed excess emission over the background due to galaxies. To confirm the COBE and the IRTS results and pursue more observational evidences, we carried out the sounding rocket experiment named the Cosmic Infrared Background ExpeRiment (CIBER). The CIBER is successfully launched on July 10, 2010 at White Sands Missile Range, New Mexico, USA. It consists of three kinds of instruments. We report the results obtained by LRS (Low Resolution Spectrometer) which is developed to fill the uncovered spectrum around 1${\mu}m$. LRS is a refractive telescope of 5.5 cm aperture with spectral resolution of 20 - 30 and wavelength coverage of 0.7 to 2.0${\mu}m$. After subtracting foreground components (zodiacal light, integrated star light and diffuse galactic light) from the sky brightness of observed five fields, there remained significant residual emission (even for the lower limit case) consistent with the IRTS and the COBE results. In addition, there exists a clear gap at 0.7 - 0.8${\mu}m$ in the CNB spectrum over the background due to galaxies according to recent results (Matsuoka et al. 2011; Mattila et al. 2011). The origin of the excess emission could be ascribed to the Pop.III stars with its active era of z = 7 - 10.

• Journal of Korea Spatial Information System Society
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• v.12 no.1
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• pp.66-75
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• 2010

The authors argues that the current road updating system based on traditional aerial photograph or multi-spectral satellite image appears to be non-user friendly due to lack of the frequent cartographic representation for the new construction sites. Google Earth are currently being emerged as one of important places to extract road features since the RGB satellite image with high multi-temporal resolution can be accessed freely over large areas. This paper is primarily intended to evaluate optimal threshold of RGB pixel values to extract road features from Google Earth. An empirical study for five experimental sites was conducted to confirm how a RGB picture provided Google Earth can be used to extact the road feature. The results indicate that optimal threshold of RGB pixel values to extract road features was identified as 126, 125, 127 for manual operation which corresponds to 25%, 30%, 19%. Also, it was found that display scale difference of Google Earth was not very influential in tracking required RGB pixel value. As a result the 61cm resolution of Quickbird RGB data has shown the potential to realistically identified the major type of road feature by large scale spatial precision while the typical algorithm revealed successfully the area-wide optimal threshold of RGB pixel for road appeared in the study area.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.21-35
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• 2009

KOMPSAT-2 is the seventh high-resolution image satellite in the world that provides both 1m-grade panchromatic images of the GSD and 4m-grade multispectral images of the GSD. It's anticipated to be used across many different areas including mapping, territory monitoring and environmental watch. However, due to the complexity and security concern involved with the use of the MSC, the use of KOMPSAT-2 images are limited in terms of geometric images, such as satellite orbits and detailed mapping information. Therefore, this study aims to produce DEM and orthoimage by using the stereo images of KOMPSAT-2, and to explore the applicability of geo-spatial information with KOMPSAT -2. Orientation interpretations were essential for the production of DEM and orthoimage using KOMPSAT-2 images. In the study, they are performed by utilizing both RPC and GCP. In this study, the orientation interpretations are followed by the generation of DEM and orthoimage, and the analysis of their accuracy based on a 1:5,000 digital map. The accuracy analysis of DEM is performed and the results indicate that their altitudes are, in general, higher than those obtained from the digital map. The altitude discrepancies on plains, hills and mountains are calculated as 1.8m, 7.2m, and 11.9m, respectively. In this study, the mean differences between horizontal position between the orthoimage data and the digital map data are found to be ${\pm}3.081m$, which is in the range of ${\pm}3.5m$, within the permitted limit of a 1:5,000 digital map. KOMPSAT-2 images are used to produce DEM and orthoimage in this research. The results suggest that DEM can be adequately used to produce digital maps under 1:5,000 scale.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.52.2-52.2
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• 2014

The Immersion Grating Infrared Spectrometer (IGRINS) is an unprecedentedly minimized infrared cross-dispersed echelle spectrograph with a high-resolution and high-sensitivity optical performance. A silicon immersion grating features the instrument for the first time in this field. IGRINS will cover the entire portion of the wavelength range between 1.45 and $2.45{\mu}m$ accessible from the ground in a single exposure with spectral resolution of 40,000. Individual volume phase holographic (VPH) gratings serve as cross-dispersing elements for separate spectrograph arms covering the H and K bands. On the 2.7m Harlan J. Smith telescope at the McDonald Observatory, the slit size is $1^{\prime\prime}{\times}15^{\prime\prime}$. IGRINS has a $0.27^{\prime\prime}$ pixel-1 plate scale on a $2048{\times}2048$ pixel Teledyne Scientific & Imaging HAWAII-2RG detector with SIDECAR ASIC cryogenic controller. The instrument includes four subsystems; a calibration unit, an input relay optics module, a slit-viewing camera, and nearly identical H and K spectrograph modules. The use of a silicon immersion grating and a compact white pupil design allows the spectrograph collimated beam size to be 25mm, which permits the entire cryogenic system to be contained in a moderately sized rectangular vacuum chamber. The fabrication and assembly of the optical and mechanical hardware components were completed in 2013. In this presentation, we describe the major design characteristics of the instrument and the early performance estimated from the first light commissioning at the McDonald Observatory.

• Sleep Medicine and Psychophysiology
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• v.17 no.2
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• pp.91-99
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• 2010

Objectives: Deficit schizophrenia (DS) constitutes a disease separate from non-deficit schizophrenia (NDS). The aim of the current study was to compare the quantitative EEG and low resolution electromagnetic tomography (LORETA) imaging between DS and NDS. Methods: This study was performed by 32 channels EEG for 42 schizophrenia patients who we categorized into DS and NDS using proxy instrument deficit syndrome (PDS). We performed the absolute power spectral analyses for delta, theta, alpha, low beta and high beta activities. We compared power spectrum between two groups using Independent t-test. Partial correlation test was performed with clinical parameters. Standardized LORETA (sLORETA) was used for comparison of cortical activity, and statistical nonparametric mapping (SnPM) was applied for the statistical analysis. Results: DS showed significantly increased delta and theta absolute power in fontal and parietal region compared with NDS (p<0.05). Power spectrum showed significant correlation with 'anergia' and 'hostility/suspiciousness' subscale of brief psychiatric rating scale (BPRS)(p<0.05). sLORETA found out the source region (anterior cingulate cortex/limbic part) that delta activity was significantly increased in DS (p=0.042). Conclusions: DS showed different cortical activity compared with NDS. Our results may suggest QEEG and LORETA could be the marker in differentiating between DS and NDS.

• Journal of Sensor Science and Technology
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• v.8 no.5
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• pp.359-367
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• 1999

CsI(Li) single crystals doped with 0.02, 0.1, 0.2 and 0.3 mole% lithium as an activator were grown by Czochralski method. The lattice structure of grown CsI(Li) single crystal was bcc, its lattice constant was $4.568\;{\AA}$. The absorption edge of CsI(Li) single crystal was 245 nm, and the spectral range of luminescence was $300{\sim}600\;nm$, its maximum luminescence intensity appeared at 425 nm. The energy resolutions of CsI(Li) single crystal doped with 0.2 mole% lithium were 14.5% for $^{137}Cs$(662 keV), 11.4% for $^{54}Mn$(835 keV) and 17.7% and 7.9% for $^{22}Na$(511 keV and 1275 keV), respectively. The relation formula of $\gamma$-ray energy versus energy resolution was ln (FWHM%) = -0.893lnE + 8.456 and energy calibration formula was ${\log}E_r=1.455\;{\log}(ch.)-1.277$. The phosphorescence decay time of CsI(Li) crystal doped with 0.2 mole% lithium was 0.51 s at room temperature, and its time resolution measured by CFT(constant-fraction timing method) was 9.0 ns.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.1
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• pp.73-79
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• 2020

Modern radar system requires high spectral purity and low phase noise characteristics for very low RCS target detection and high resolution SAR (Synthetic Aperture Radar) image. This paper presents a new X-band high stable frequency synthesizer for high performance radar system, which combines DAS (Direct Analog Synthesizer) and DDS (Direct Digital Synthesizer) techniques, in order to cope with very low phase noise and high frequency agility requirements. This synthesizer offers more than 10% operating bandwidth in X-band frequency and fast agile time lower than 1 usec. Also, the phase noise at 10kHz offset is lower than -136dBc/Hz, which shows an improvement of more than 10dB compared to the current state of art frequency synthesizer. This architecture can be applied to L-band and C-band application as well. This frequency synthesizer is able to used in modern AESA (Active Electronically Scanned Array) radar system and high resolution SAR application.

• Korean Journal of Remote Sensing
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• v.35 no.6_2
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• pp.1133-1148
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• 2019

Tree growth and vitality in forest shows seasonal changes. So, in order to detect forest damage accurately, we have to use satellite images before and after damages taken at the same season. However, temporal resolution of high or medium resolution images is very low,so it is not easy to acquire satellite images of the same seasons. Therefore, in this study, we estimated spectral information of the same DOY using time-series Landsat images and used the estimates as reference values to assess forest damages. The study site is Hwasun, Jeollanam-do, where forest damage occurred due to hail and drought in 2017. Time-series vegetation index (NDVI, EVI, NDMI) maps were produced using all Landsat 8 images taken in the past 3 years. Daily normal vegetation index maps were produced through cloud removal and data interpolation processes. We analyzed the difference of daily normal vegetation index value before damage event and vegetation index value after event at the same DOY, and applied the criteria of forest damage. Finally, forest damage map based on daily normal vegetation index was produced. Forest damage map based on Landsat images could detect better subtle changes of vegetation vitality than the existing map based on UAV images. In the extreme damage areas, forest damage map based on NDMI using the SWIR band showed similar results to the existing forest damage map. The daily normal vegetation index map can used to detect forest damage more rapidly and accurately.

• Korean Journal of Remote Sensing
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• v.24 no.4
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• pp.289-298
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• 2008

An algorithm was developed to retrieve both cloud optical thickness and effective particle radius considered the aerosol effect on clouds. This study apply the algorithm of Nakajima and Nakajima (1995) that is used to retrieve cloud optical thickness and effective particle radius from visible, near infrared satellite spectral measurements. To retrieve cloud properties, Look-up table (LUT) was made under different atmospheric conditions by using a radiative transfer model. Especially the vertical distribution of aerosol is based on a tropospheric aerosol profile in radiative transfer model. In the case study, we selected the extensive forest fire occurred in Russia in May 2003. The aerosol released from this fire may be transported to Korea. Cloud properties obtained from these distinct atmospheric situations are analysed in terms of their possible changes due to the interactions of the clouds with the aerosol particle plumes. Cloud properties over the East sea at this time was retrieved using new algorithm. The algorithm is applied to measurements from the MODerate Resolution Imaging Spectrometer (MODIS) onboard the Terra spacecrafts. As a result, cloud effective particle radius was decreased and cloud optical thickness was increased during aerosol event. Specially, cloud effective particle radius is hardly greater than $20{\mu}m$ when aerosol particles were present over the East Sea. Clouds developing in the aerosol event tend to have more numerous but smaller droplets.