• 한국세라믹학회지
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• 제37권8호
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• pp.781-786
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• 2000

An Er-doped sulfide fiber was drawn, and its spectroscopic properties were analyzed. Compositions of a 1000 ppmwt Er3+-doped core and an undoped clad were Ge30-Ga1-Asg-S61 and Ge30-As8-S62, in at.%, respectively. Refractive index of the core composition was approximately 0.01 high than that of the clad. In order to enhance the mechanical stability as well as to prevent infiltration of impurity ions such as OH-, an UV-curable polymer was used for the coating. The optical loss of a fiber formed directly from a polymer coated core rod without cladding was ∼15 dB/m at 1.06$\mu\textrm{m}$. In the case of a fiber with core/clad structure, the optical loss was so high that the stimulated emission of erbium fluorescence was not evident. It is believed that presence of inhomogeneous core/clad interface and crystalline aggregates precipitated in the clad region were responsible for the high optical loss. On the other hand, fluorescence characteristics of Er3+ embedded in the core region were more or loss deteriorate compared to fiber preform, which is attributed to the redistribution of the Er ions along with the partial crystallization of the core glass during the fiberization process.

• Journal of the Korean Wood Science and Technology
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• 제46권3호
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• pp.285-296
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• 2018

ISPM No. 15에 의거한 열처리 목재의 검증을 위한 연구로서 열처리 목재 표면의 분광학적 특성을 분석하였다. IR 스펙트럼 상에서는 다양한 작용기들이 확인되지만 수종간, 열처리 시간 및 보관 기간에 따른 특별한 차이를 발견하기 어려웠다. HBI(hydrogen-bonding intensity)는 보관 기간에 따른 열처리 목재의 변화는 관찰할 수 있지만 열처리 시간에 따른 변화는 관찰하기 어려웠다. 하지만 PCA score plot 상에서 수종 내에서 60분 혹은 90분의 열처리 시간에 따라 목재의 분류가 가능하였다. PCA에서 열처리 목재의 분류의 기준은 목재 내 리그닌의 방향족 환과 셀룰로오스의 C-H bending이었으며 이들 성분에 의해 ISPM No. 15로 열처리된 목재를 분류할 수 있었다.

• 천문학회지
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• 제52권3호
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• pp.57-69
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• 2019

We present an analysis of the chemical abundances and kinematics of six low-mass dwarf stars, previously claimed to be candidate hypervelocity stars (HVSs). We obtained moderate-resolution (R ~ 6000) spectra of these stars to estimate the abundances of several chemical elements (Mg, Si, Ca, Ti, Cr, Fe, and Ni), and derived their space velocities and orbital parameters using proper motions from the Gaia Data Release 2. All six stars are shown to be bound to the Milky Way, and in fact are not even considered high-velocity stars with respect to the Galactic rest frame. Nevertheless, we attempt to characterize their parent Galactic stellar components by simultaneously comparing their element abundance patterns and orbital parameters with those expected from various Galactic stellar components. We find that two of our program stars are typical disk stars. For four stars, even though their kinematic probabilistic membership assignment suggests membership in the Galactic disk, based on their distinct orbital properties and chemical characteristics, we cannot rule out exotic origins as follows. Two stars may be runaway stars from the Galactic disk. One star has possibly been accreted from a disrupted dwarf galaxy or dynamically heated from a birthplace in the Galactic bulge. The last object may be either a runaway disk star or has been dynamically heated. Spectroscopic follow-up observations with higher resolution for these curious objects will provide a better understanding of their origin.

• 한국물환경학회지
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• 제27권5호
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• pp.625-633
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• 2011

A long-term water quality monitoring in the Han River Basin reveals a consistent increasing trend for the concentration of refractory organic matter (R-OM) in major monitoring sites of the watershed. Because the determination of R-OM concentrations typically requires a long time of microbial incubation, it is essential to present the estimation indices for R-OM for an efficient watershed management. In this study, a number of surface water samples were classified into three groups, each of which were collected from Lake Paldang, rivers at rain and non-rain events, respectively. The corresponding R-OM concentrations were correlated with biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) concentrations as well as ultraviolet and fluorescence intensities of the filtered samples. Among the traditional organic matter parameters, TOC exhibited the highest correlation coefficient with the R-OM concentrations regardless of the types of the sample groups. The equations for conversing TOC into R-OM concentrations were finally suggested as $0.43{\times}TOC+1.12$, $0.44{\times}TOC+0.61$, $0.24{\times}TOC+1.28$ for river samples at rain and non-rain events, and lake samples, respectively. TOC-BOD(C), the values of the TOC concentrations subtracted by carbon-converted BOD concentrations, was a good index for estimating the absolute concentrations of R-OM. UV absorbance at 254 nm was well correlated with R-OM concentrations of river samples while fluorescence intensities at 350 nm showed an excellent relationship with R-OM concentration of the lake samples. Our results suggests that simple spectroscopic parameters could be applied for in-situ monitoring tool techniques in watersheds.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2009년도 춘계학술발표회 논문집
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• pp.23-28
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• 2009

The purpose of this study was to improve not only wet-end performances but also paper characteristics by the modification of various factors like molecular design and ionic characteristics of polyacrylamides First of all physical characteristics were observed after modify molecular design of the cationic polyacrylamides to linear, branched and cross-linked. In addition it was found analysis method to confirm branch degree of cationic polyacrylamides to combine ionic titration characteristics and spectroscopic behavior, After application of these structure modified polyacrylamides to the multiple retention systems with inorganic microparticles, it was found adjusting of branch degree of polyacrylamides was very important to optimize wet-end improvement. Second, After polymerization of amphoteric polyacrylamide to have both of cationic and anionic functional group in the polymer, we observed not only physical characteristics but also wet-end improvement to apply recycled pulp and found that the improvement of solution stability to prevent hydrolysis and increase of ash retention dramatically to compare traditional cationic polyacrylamide retention aid, Finally, After polymerization of anionic polyacrylamide, we observed not only wet-end improvement but also paper characteristics to apply preflocculation of PCC and it was found the improvements of flocculation efficiency, retention, ash retention, optical properties of the paper and bursting strength to compare traditional preflocculant of cationic polyacrylamide.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
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• pp.12-15
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• 2001

Polycrystalline diamond films are deposited by cyclic method. modulating the $H_2$ Plasma and $CH_4+H_2$ plasma during the growth step. Diamond quality is evaluated by FWHM and $I_D/I_G$ ratio obtained from Raman spectroscopic analysis. Structural defects and impurities generated during the growth step are characterized by cathodoluminescence, and the variations between band-A(430 nm) line and nitrogen-related(578 nm) line are investigated as a function of $T_E/T_G$. Furthermore, the correlations between preferential orientation. film morphologies and CL characteristics are also investigated.

• 한국수소및신에너지학회논문집
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• 제17권4호
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• pp.425-433
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• 2006

Sepiolite was selected as a mineral carbonation candidate ore for carbon dioxide sequestration. Carbonation salt formation from alkaline earth metal ingredient needs to dehydroxylation of sepiolite at high temperature. An evident dehydroxylation was observed over $800^{\circ}C$ and the variations of sepiolite characteristics after high temperature treatment was synthetically evaluated. Remarkable weight loss were measured after high temperature thermochemical reaction then crystallographic and spectroscopic changes were analyzed. The resulted alkaline earth metal oxides could explained by dehydroxylation based on thermochemical reaction.

• KSBB Journal
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• 제15권3호
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• pp.318-322
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• 2000

An oxygen-sensitive fumarate reductase has been purified from the cytosol fraction of the Enterococcus faecalis RKY1 grown anaerobically on a defined medium containing glycerol and fumarate. A major portion of the purification was performed with employing Triton X-100 and reducing agents by Phenyl-sepharose CL-4B DEAE-sepharose and Dephadex G-150 The final activity was 0.42 unit/mg. The deduced molecular mass of active band was 66 kDa. The optimal pH and temperature for the activity were 7.0 and 38$^{\circ}C$ respectively. The enzyme activity was not affected by 1mM metal ions such as bacl2 $.$2H2O HgCl2 MnCl2$.$4H2O ZnCl2 CuCl2$.$2H2O Mgcl2$.$6H2O FeSo4$.$7H2O and by EDTA. Partially purified enzyme ws yellow in color ; spectroscopic study indicated the presence of flavins as a cofactor.

• 한국진공학회지
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• 제5권3호
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• pp.188-193
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• 1996

A new display -type spherical mirror analyzer has been characterized in terms of the performance and the auger spectra taken by using it. The final goal with the analyzer is to devleop SET(Surface Electron Spectroscopic Tomography) which is capable to provide a 3-dimensional layer-by-layer information nondestructively. This kind of analyzer was originally designed by H.Daimon. The main feature is to display 2-dimensional electronic structures directly onto a screen. In our case, an external micro-electron beam was employed as an excitation source. However, this invokes various problems because of the interference between the electron beam and the analyzer. The problems have been solved through the optimization of various parameters of the analyzer.

• 한국미생물·생명공학회지
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• 제23권1호
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• pp.81-86
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• 1995

A Streptomyces strain YS-943, which produced amino acid antimetabolite, was isolated from soil. During the course of screening for new amino acid antimetabolites from the culture broth of Actinomycetes, we found that the strain produced a substance active against Gram-positive bacteria and its activity was reversed by L-methionine and L-histidine on the synthetic minimal agar medium in the culture broth.The morphological and cultural characteristics serve to identify the producing organism strain YS-943 as the genus Streptomyces. Fermentation was carried out in the synthetic medium at 28$\CIRC$C for 48 hours. The fermentation yield reached about 12 mg per liter of the broth. The YS-943 substance was obtained as white powder, mp 194$\CIRC$C and has the molecular formular of C$_{4}$H$_{8}$N$_{2}$O$_{4}$. Its structure was determined to be o-carbamyl-D-serine by spectroscopic data. It is active against some Gram-positive bacteria and reversed by L-methionine and L-histidine.