• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.348-354
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• 1994

Chitin and chitosan samples prepared from crab's shells under different conditions were compared for their physicochemical properties; and functionality in gastrointestinal tract by in vitro test. Their bulk density was in the range of $127{\sim}208\;mg/ml$, and their viscosity was $80{\sim}581\;cP$ in 0.1 chitin and $80{\sim}3,670\;cP$ in 0.5% chitosan solution, showing a wide variation. The degree of deacetylation in chitosan samples as determined by IR spectral analysis was relatively high, showing $81{\sim}93%$. At the same alkali concentration and reaction temperature, a longer reaction period gave an increased degree of deacetylation and lower viscosity. The water holding capacity of chitic substance became greater at higher soaking temperature; chitosan D at $37^{\circ}C$ showed the greatest value. Chitic substance with lower bulk density showed the higher water holding capacity. The retardation effect toward glucose absorption was higher in critic substances of lower density and higher water holding capacity; chitosan D showed the highest value of 38%. The retardation index toward bile acid absorption after 1 hour dialysis was $15{\sim}34%$ in chitic substances, 39% in pectin and 9% in cellulose. The retarding effect showed the highest value of 34% in chitosan D at 3% concentration.

• Geophysics and Geophysical Exploration
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• v.17 no.4
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• pp.216-230
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• 2014

Based on the interpretation of 3D seismic profiles acquired in the northwestern area of the Ulleung Basin, East Sea, the shallow sediments consist of five seismic units separated by regional reflectors. An anticline is present in the study area that documents activity of many faults. Bottom simulating reflectors are characterized by high RMS amplitude. Acoustic blanking with low RMS amplitude is distinctively recognized in the gas hydrate stability zone. Seismic attribute analysis shows that if gas hydrates are underlain by free gas, the high reflection strength and the low instantaneous frequency are displayed below the boundary between them. Whereas, if not, the reflection strength is low and instantaneous frequency is high continuously below the gas hydrate zone. Based on the spectral decomposition of the bottom simulating reflector, the high envelope at the specific high frequency range indicates the generation of the tuning effect due to the lower free gas content. Four models for the occurrence of the gas hydrate are suggested considering the slope of sedimentary layers as well as the presence of gas hydrate or free gas.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.5
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• pp.544-555
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• 2002

The aim of this study is to develop the $^1H$-MRS data postprocessing software for both single-voxel and multi-voxel technique, which plays and important role as a diagnostic tool in clinical field. This software is based on graphical user interface(GUI) under windows operating system of personal computer(PC). In case of single-voxel MRS, both of raw data in time-domain and spectrum data in frequency-domain are simultaneously displayed in a screen. Several functions such as DC correction, zero filling, line broadening, Lorentz-Gauss filtering and phase correction, etc. are included to increase the quality of spectrum data. In case of multi-voxel analysis, spectroscopic image reconstructed by 3-D FFT was displayed as a spectral grid and overlapped over previously obtained T1- or T2-weighted image for the spectra to be spatially registered with the image. The analysis of MRS peaks were performed by obtaining the ratio of peak area. In single-voxel method, statistically processed peak-area ratios of MRS data obtained from normal human brain are presented. Using multi-voxel method, MR spectroscopic image and metabolite image acquired from brain tumor are demonstrated.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.70.1-70.1
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• 2013

New space program for "Next-Generation Small Satellite (NEXTSat)" launched last year after the success of the series of Science & Technology Satellite (STSAT). KASI proposed the near-infrared imaging spectrometer as a scientific payload onboard NEXTSat-1. It was selected as one of two scientific payloads. The approved scientific payload is the near-infrared imaging spectrometer for the study of star formation history (NISS). The efficient near-infrared observation can be performed in space by evading the atmospheric emission as well as other thermal noise. The observation of cosmic near-infrared background enables us to reveal the early Universe in an indirect way through the measurement of absolute brightness and spatial fluctuation. The detection of near-infrared spectral lines in nearby galaxies, cluster of galaxies and star forming regions give us less biased information on the star formation. In addition, the NISS will be expected to demonstrate our technologies related to the development of the Korea's leading near-infrared instrument for the future large infrared telescope, SPICA.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.12
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• pp.1858-1864
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• 2014

In the present investigation, the anti-diabetic potential of 80% ethanol extract of Eleutherococcus senticosus leaves (EEES) was examined based on ${\alpha}$-glucosidase inhibitory activities. EEES was sequentially fractionated with n-hexane, chloroform, ethyl acetate (EtAOc), n-butanol, and $H_2O$. Of the various fractions, EtAOc fraction effectively inhibited ${\alpha}$-glucosidase activity by 68.05%. Therefore, EtAOc fraction was selected for further isolation and identification studies. EtAOc fraction was separated by medium pressure liquid chromatography with silica and ODS gel to yield eight fractions (EAA~EAH). Based on the results of ${\alpha}$-glucosidase inhibitory activity, EAH fraction was re-chromatographed to yielded four more fractions (EAHA~EAHD). Of these, EAHC fraction showed higher ${\alpha}$-glucosidase inhibitory activity of 93.60%. EAHC fraction was re-chromatographed and yielded EAHCA and EAHCB fractions. Further, identification and chemical structures of these two fractions were analyzed using $^1H$-NMR, $^{13}C$-NMR, and mass spectra data. Based on the results of the spectral data, the isolated compounds were identified as hyperoside and isoquercetin. Results of the present study indicate that the isolated compounds, hyperoside, and isoquercetin from leaves of E. senticosus could be used for the development of new anti-diabetic drugs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.6
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• pp.1407-1412
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• 2014

In order to improve spectrum sensitivity of photodiode for detection of the laser at 850 nm ~ 1000 nm of near-infrared wavelength band, this study has produced silicon-based fast film PIN photodiode and analyzed electrical and optical properties. The manufactured device is packaged in TO-18 type. The electrical properties of the dark currents both Anode 1 and Anode 2 have valued of approximately 0.055 nA for 5 V reverse bias, while the capacitance showed 19.5 pF at frequency range of 1 kHz and about 19.8 pF at the range of 200 kHz for 0 V. In addition, the rising time of output signal was verified to have fast response time of about 30 ns for 10 V. For the optical properties, the best spectrum sensitivity was 0.66 A/W for 880 nm, while it was relatively excellent value of 0.45 A/W for 1,000 nm.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.6
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• pp.523-530
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• 2017

In this study, a method of probabilistic evaluation of the performance point of the structure obtained by capacity spectrum method (CSM) is presented. The performance point of the 4-story and 1-bay steel structure was determined by using CSM according to ATC-40. In order to analyze whether the demand spectrums exceed the performance limit of the structure, the limit displacements are derived for the performance limit of the structure defined from the plastic deformation angle of the structural member. In addition, by selecting a total of 30 artificial seismic wave having the response spectrum similar to the design response spectrum, the fragility curves were derived by examining whether the response spectrum obtained from the artificial seismic wave were exceeded each performance limit according to the spectral acceleration. The maximum likelihood method was used to derive the fragility curve using observed excess probabilities. It has been confirmed that there exists a probability that the response acceleration value of the design response spectrum corresponding to each performance limit exceeds the performance limit. This method has a merit that the stochastic evaluation can be performed considering the uncertainty of the seismic waves with respect to the performance point of the structure, and the analysis time can be shortened because the incremental dynamic analysis (IDA) is not necessary.

• Investigative Magnetic Resonance Imaging
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• v.20 no.2
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• pp.81-87
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• 2016

Purpose: To analyze the feasibility of three-dimensional (3D) diffusion-weighted (DW) PSIF (reversed FISP [fast imaging with steady-state free precession]) sequence in order to evaluate peripheral nerves in the elbow. Materials and Methods: Ten normal, asymptomatic volunteers were enrolled (6 men, 4 women, mean age 27.9 years). The following sequences of magnetic resonance images (MRI) of the elbow were obtained using a 3.0-T machine: 3D DW PSIF, 3D T2 SPACE (sampling perfection with application optimized contrasts using different flip angle evolution) with SPAIR (spectral adiabatic inversion recovery) and 2D T2 TSE (turbo spin echo) with modified Dixon (m-Dixon) sequence. Two observers used a 5-point grading system to analyze the image quality of the ulnar, median, and radial nerves. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of each nerve were measured. We compared 3D DW PSIF images with other sequences using the Wilcoxon-signed rank test and Friedman test. Inter-observer agreement was measured using intraclass correlation coefficient (ICC) analysis. Results: The mean 5-point scores of radial, median, and ulnar nerves in 3D DW PSIF (3.9/4.2/4.5, respectively) were higher than those in 3D T2 SPACE SPAIR (1.9/2.8/2.8) and 2D T2 TSE m-Dixon (1.7/2.8/2.9) sequences (P < 0.05). The mean SNR in 3D DW PSIF was lower than 3D T2 SPACE SPAIR, but there was no difference between 3D DW PSIF and 2D T2 TSE m-Dixon in all of the three nerves. The mean CNR in 3D DW PSIF was lower than 3D T2 SPACE SPAIR and 2D T2 TSE m-Dixon in the median and ulnar nerves, but no difference among the three sequences in the radial nerve. Conclusion: The three-dimensional DW PSIF sequence may be feasible to evaluate the peripheral nerves around the elbow in MR imaging. However, further optimization of the image quality (SNR, CNR) is required.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.422-433
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• 2017

Unmanned Aerial Vehicle (UAV) has several advantages over conventional remote sensing techniques. They can acquire high-resolution images quickly and repeatedly. And with a comparatively lower flight altitude, they can obtain good quality images even in cloudy weather. In this paper, we developed for estimating garlic growth at field scale model in major cultivation regions. We used the $NDVI_{UAV}$ that reflects the crop conditions, and seven meteorological elements for 3 major cultivation regions from 2015 to 2017. For this study, UAV imagery was taken at Taean, Changnyeong, and Hapcheon regions nine times from early February to late June during the garlic growing season. Four plant growth parameters, plant height (P.H.), leaf number (L.N.), plant diameter (P.D.), and fresh weight (F.W.) were measured for twenty plants per plot for each field campaign. The multiple linear regression models were suggested by using backward elimination and stepwise selection in the extraction of independent variables. As a result, model of cold type explain 82.1%, 65.9%, 64.5%, and 61.7% of the P.H., F.W., L.N., P.D. with a root mean square error (RMSE) of 7.98 cm, 5.91 g, 1.05, and 3.43 cm. Especially, model of warm type explain 92.9%, 88.6%, 62.8%, 54.6% of the P.H., P.D., L.N., F.W. with a root mean square error (RMSE) of 16.41 cm, 9.08 cm, 1.12, 19.51 g. The spatial distribution map of garlic growth was in strong agreement with the field measurements in terms of field variation and relative numerical values when $NDVI_{UAV}$ was applied to multiple linear regression models. These results will also be useful for determining the UAV multi-spectral imagery necessary to estimate growth parameters of garlic.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.5
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• pp.11-21
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• 2008

In recent years, time history analysis has been the method generally used for the seismic analysis of tall buildings with damping devices. When T is the natural period of the first vibration mode of the structure, the sum of the spectral acceleration of the earthquake ground motion is usually adjusted to that of the design response spectrum in the period ranging from 0.2T to 1.5T to meet the requirements of design code. However, when the ground motion is scaled according to the design code, the differences in the responses obtained by response spectrum analysis (RSA) and time history analysis (THA) of the structures increase as the natural period of the structure becomes longer. When time history analysis is performed by using ground accelerations that are scaled according to the design code, base shear is similar to that obtained from RSA, but other responses, such as displacements, drifts and member forces, are underestimated compared to RSA. If these results are adjusted by multiplying with the scale-up factor, the scaled responses become much smaller. Therefore, a scaling method of ground motions corresponding with the design code is proposed in this study, as a way of assisting structural engineers in generating artificial ground motions.