• 한국습지학회지
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• 제14권4호
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• pp.439-455
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• 2012

파랑 수치모형인 SWAN 수치모형, 파랑에 의해 발생되는 기인력 수치모형인 WIF 수치모형, 그리고 흐름장 수치모형은 EFDC 수치모형을 연동하여 최종적으로 파랑류 계산이 가능한 WIC 수치모형을 개발하였다. 개발된 WIC 수치모형을 검증하기 위하여 Goda(2000)가 적용한 수중 원형천퇴의 파랑변형 계산하여 파고, 파랑의 굴절과 회절을 비교하였으며, 파고비 결과는 약 1~5 %의 차이를 보였다. 파랑에 의한 기인력 수치모형은 기존의 Longuet-Higgins and Stewart(1960)가 제안한 잉여응력에 의해 발생하는 기인력에 Dally and Osiecki(1994)가 제안한 roller로 인한 응력에 의해 발생되는 기인력을 추가하였고, Kim(2004)이 제안한 완화기법을 도입하여 lateral mixing 처리를 수행하지 않아도 자연현상과 유사한 결과를 얻을 수 있도록 개발되었다. 개발된 파랑에 의한 기인력 수치모형은 계산시 ${\Delta}t$에 제약을 받지 않는다는 장점을 가지고 있으며, 흐름장 수치모형의 source항이 되어 파랑류의 양상을 계산할 수 있도록 하였다. 연계된 파랑류 수치모형을 검증하기 위해서 Nishimura et al.(1985)의 수리모형실험과 Kim(2004)의 수심적분된 파랑류 수치모형과 비교하였다. 이안제 배후에서 연안류의 유속분포와 이안류의 유속분포 결과가 기존의 수리모형실험과 수치모형실험의 결과와 상당히 일치함이 관측되었다.

• 대한원격탐사학회지
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• 제29권2호
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• pp.243-251
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• 2013

본 연구는 인공위성과 지상 원격탐사 자료를 이용하여 동북아 지역에서 발생하는 황사현상의 중장거리 이동에 따른 광학적 특성 변화를 분석하였다. 동북아시아 지역의 Aerosol Robotic Network(AERONET)의 선포토미터 관측 지점 중에 황사의 발원지로 Dunhuang과 Inner-Mongolia, 발원지에 근접한 풍하측 지점으로 Yulin과 Beijing, 그리고 장거리 이동 지점으로 한국의 Anmyon과 Gosan, 일본의 Noto, 이렇게 7곳을 선정하여 자료를 분석하였다. 황사의 발생 및 이동 경로를 파악하기 위하여 자외선 원격탐사 기법을 사용하는 인공위성인 Ozone Monitoring Instrument(OMI) 관측자료를 활용하였다. 발원지에서의 단산란알베도는 440 nm에서 0.90에서 0.96 사이의 값으로 높았으나 풍하측이나 장거리 이동 지역에서는 그 값이 감소하였다. 또한, 파장에 따른 단산란알베도 값의 차이는 발원지에서는 높게 나타났으나 이동된 지역에서는 그 차이가 감소하였다. 이러한 장거리 이동에 따른 황사의 광흡수 특성의 변화는 이동 중 탄소입자와 같은 대기 오염물질과의 혼합으로부터 기인하는 것으로 판단된다.

• 대한원격탐사학회지
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• 제29권4호
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• pp.407-413
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• 2013

본 연구에서는 에어로졸의 종류에 따른 광흡수 특성을 표시할 수 있는 새로운 에어로졸 파라미터인 Modified Aerosol Factor(MAF)를 산출하였다. MAF는 AERONET의 선포토미터로부터 산출되는 4 파장(440, 675, 870 그리고 1020 nm)의 단산란알베도로부터 도출되었다. 에어로졸 종류에 단산란알베도 값이 파장 증가에 따라 다른 형태를 보이는 점으로부터 4파장의 단산란알베도를 이용하여 선형회귀분석을 수행하고 분석값의 기울기 값을 산출하였다. 먼지입자는 기울기 값이 양의 값을 보이고, 순수한 먼지입자 일수록 높은 값을 보였다. 다른 종류의 에어로졸이 혼합됨에 따라 기울기 값은 감소하였다. 먼지입자를 제외한 오염입자와 smoke 입자는 음의 값을 보였다. 광흡수 특성의 차이를 파악하기 위하여 1020 nm에서의 단산란알베도 값을 보정하였다. 보정된 단산란알베도와 기울기 값을 합하여 MAF를 도출하였다. MAF는 오염입자와 smoke 입자는 -1, 먼지입자는 1.5의 값을 보였으며, 서로 다른 에어로졸 종류별로 광흡수 특성이 높을수록 낮은 값의 분포를 보였다.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.51-54
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• 2003

We analyzed radiative properties of aerosols, $CO^{2}$ and clouds using Optical Properties of Aerosols and Clouds(OPAC) and the Column Radiation Model (CRM). From OPAC, if the soot component is disregarded, dust-like components depict the highest extinction values in the solar spectral range and the lowest. single scattering albedoes, which are attributable to the presence of large particles. In the dust aerosol, the high absorptivity in the infrared may induce a warming of the lower atmospheric layer in the nighttime. The radiative properties of aerosols, clouds and double $CO^{2}$ using the CRM model at Seoul (37N, 127.4 E) on 3 April 2003 were calculated. The solar zenith angle is 65˚ and the surface albedo is 0.1836 during the clear day. The aerosol optical depth change 0.14 to 1.7, which is derived during Asian dust days in Korea. At this time, abedo by aerosols is considered as 0.3. In cloudy condition, the short wave cloud forcing on both the TOA and the surface is -193.89 $Wm^{-2}$ and -195.03 $Wm^{-2}$, respectively, and the long wave cloud forcing is 19.58 $Wm^{-2}$ and 62.08 $Wm^{-2}$, respectively. As a result, the net radiative cloud forcing is -174.31 $Wm^{-2}$ and -132.95 $Wm^{-2}$, respectively. We calculate also radiative heating rates by double $CO^{2}$ during the clear day. The $CO^{2}$ volumn mixing ratio is 3.55E-4.

• Journal of the Korean Wood Science and Technology
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• 제16권4호
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• pp.3-9
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• 1988

Infrared (IR) spectroscopic techniques for the analysis of wood samples and the absorbance spectra of solid woods were presented. KBr pellets were prepared by throughly mixing approximately 300 mg of dried KBr and 1 mg of finely milled wood powder extracted with ethanol-cyclohexane previously. This mixture was made into a transparent disc by means of a pellet-making die (10 ton/$cm^2$ for 10 min). This IR techniques were applied for the analysis of archaeological wood samples. The most notable difference in the IR spectra between the recent and the archaeological waterlogged woods is that the absorption band centered at $1,730cm^{-1}$ was significantly diminished in the waterlogged ones. Total loss of absorption in $1,730cm^{-1}$ might be mainly due to the result of hemicellulose degradation. Another feature indicated by IR spectral comparision are that the degraded waterlogged wood samples showed 1) the increased intensity of the 1,600, 1,500 and $1,270cm^{-1}$ due to the residual lignin and the increased intensity at 1,470 and $1,425cm^{-1}$ due to the degradation of hemicellulose and 2) to the emergence of single band around $1,050cm^{-1}$ instead of three bands at 1,110, 1,060 and $1,040cm^{-1}$ in recent wood due to the degradation of cellulose crystalline. It was revealed from the IR examinations that the first change of wood in the waterlogged situation was the lysis of hemicellulose and the second the lysis of cellulose. It was also suggested that IR spectroscopy could serve a fast method for the investigation on the chemical characteristics of archaeological wood samples.

• 한국대기환경학회지
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• 제21권1호
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• pp.1-14
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• 2005

In this study, a Long Path Differential Optical Absorption Spectroscopy system (K-JIST LP-DOAS) has been used to simultaneously measure atmospheric monoaromatic hydrocarbons and other trace compounds. The validity of the K-JIST LP-DOAS for measuring atmospheric monoaromatic hydrocarbons was tested during a field campaign between 12 February and 14 March 2003 at an urban site in Seoul, Korea through inter-comparative measurements against a collocated on-line Gas Chromatography (GC) system. The concentrations of benzene, toluene, p-xylene, and m-xylene were measured with the K-JIST LP-DOAS system in the UV region (239～302 nm) over a 740 m beam path. For the other trace compounds, a longer spectral range (299～362 nm) was used. In order to remove the interference of atmospheric abundant species (such as oxygen, sulfur dioxide and ozone), two oxygen optical density spectra obtained at two pathlengths, 697 and 1133m, and reference spectra of sulfur dioxide and ozone were incorporated in the fitting procedure. The mean concentrations measured by our LP-DOAS during the measurement period were 0.77 ($\pm$0.38) ppbv for benzene, 3.68 ($\pm$1.90) ppbv for toluene, 0.41 ($\pm$0.19) ppbv for p-xylene, 0.54 ($\pm$0.24) ppbv for m-xylene. The concentration data of benzene, toluene, p-xylene and m-xylene obtained by our LP-DOAS were found to be in relatively good correlations with those of the online GC system. Pearson's coefficients in the observed concentrations between LP-DOAS and on-line GC were 0.84 for benzene, 0.83 for toluene and 0.65 for m,p-xylene. This study suggests that the LP-DOAS system can be used to provide reliable information on both the mixing ratios and temporal distribution characteristics of monoaromatic hydrocarbons in the urban air.

• 대한화학회지
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• 제20권5호
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• pp.398-405
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• 1976

메틸 피라진과 피라진산으로 부터 새로운 화합물 1,2-비스피라진 에틸렌을 합성하여 기기분석과 원소분석으로 이 화합물의 구조를 확인하였다. UV-VIS 스펙트럼에서는 예상했던 $(n,\;{\pi}^*)^1$ 흡수띠가 흡광도가 강한 $({\pi},\;{\pi}^*)^1$ 흡수띠에 묻혀 볼 수가 없었으나 형광에 미치는 염의 효과로 부터 $(n,\;{\pi}^*)^1$ 상태가 $({\pi},\;{\pi}^*)^1$ 상태와 거의 같은 에너지를 갖고 있음을 알았다. $77^{\circ}K$에서 형광의 양자 수득률은 0.025로서 같은 조건에서 형광 양자 수득륙이 1인 스틸벤과 좋은 대조를 이루며 이는 $(n,\;{\pi}^*)$와 $({\pi},\;{\pi}^*)$의 혼합으로 단일 상태에서 삼중 상태로의 intersystem crossing이 효율적으로 잘 일어난다는 것을 말해 준다.

• 농업과학연구
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• 제47권3호
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• pp.633-644
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• 2020

Rice paper is an element of Vietnamese cuisine that can be used to wrap vegetables and meat. Rice and starch are the main ingredients of rice paper and their mixing ratio is important for quality control. In a commercial factory, assessment of food safety and quantitative supply is a challenging issue. A rapid and non-destructive monitoring system is therefore necessary in commercial production systems to ensure the food safety of rice and starch flour for the rice paper wrap. In this study, fluorescence hyperspectral imaging technology was applied to classify grain flours. Using the 3D hyper cube of fluorescence hyperspectral imaging (fHSI, 420 - 730 nm), spectral and spatial data and chemometric methods were applied to detect and classify flours. Eight flours (rice: 4, starch: 4) were prepared and hyperspectral images were acquired in a 5 (L) × 5 (W) × 1.5 (H) cm container. Linear discriminant analysis (LDA), partial least square discriminant analysis (PLSDA), support vector machine (SVM), classification and regression tree (CART), and random forest (RF) with a few preprocessing methods (multivariate scatter correction [MSC], 1^st and 2^nd derivative and moving average) were applied to classify grain flours and the accuracy was compared using a confusion matrix (accuracy and kappa coefficient). LDA with moving average showed the highest accuracy at A = 0.9362 (K = 0.9270). 1D convolutional neural network (CNN) demonstrated a classification result of A = 0.94 and showed improved classification results between mimyeon flour (MF)1 and MF2 of 0.72 and 0.87, respectively. In this study, the potential of non-destructive detection and classification of grain flours using fHSI technology and machine learning methods was demonstrated.

• 한국수소및신에너지학회논문집
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• 제3권2호
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• pp.25-33
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• 1992

With the aim to obtain $TiO_2$ films with an increased photorespones and absorbance in the visible region of the solar spectrum, the direct oxidation of titanium alloys were performed. In this study, $Ti-Ga_2O_3$ alloy was prepared by mixing, pressing and arc melting of appropriate amounts of titanium and $Ga_2O_3$ powder. Electrochemical measurements were performed in three electrode cell using electrolyte of 1M NaOH solution. The oxide films on $Ti-Ga_2O_3$ alloy was composed of $Ti_2O$, TiO, $TiO_2$, $Ga_2TiO_5$. The free energy efficiency (${\eta}e$) of $Ti-Ga_2O_3$ oxide films had 0.8~1.3 % and were increased with the increase of $Ga_2O_3$ content up to 10wt %. The onset potential ($V_{on}$) had -0.8V~0.9V ranges and were shifted to anodic direction with the increase of $Ga_2O_3$ content. The spectral response of Ti-$Ga_2O_3$ oxides were similar to the response of the $TiO_2$ and their $E_g$ were observed to 2.90~3.0eV. Variations of onset potential($V_{on}$) associated with electrolyte pH were -59mV/pH. This probably reflects the nature of the bonding of $OH^-$ ion to the $TiO_2$ surface, a common phenomena in the transition-metal oxides.

• 센서학회지
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• 제18권5호
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• pp.365-371
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• 2009

In this study, we have fabricated a fiber-optic pH sensor which is composed of a light source, plastic optical fibers and a spectrometer. As an indicator, a phenol red is used, and a pH liquid solution is prepared by mixing of phenol red and various kinds of pH buffer solutions in these experiments. The emitting light from a light source is guided by plastic optical fibers to the pH liquid solution, and the optical characteristic of a light is changed in the pH liquid solution according to its color change. Therefore, we have measured the intensities and wavelength shifts of the modulated lights, which are changed due to the color variations of phenol red at different pH values, by using of a spectrometer for spectral analysis. Also, the relationships between the pH values of liquid solutions and the optical properties of modulated light according to the change of color of phenol red are obtained.