• Journal of Applied Biological Chemistry
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• v.62 no.4
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• pp.323-326
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• 2019

The flowers of Coreopsis lanceolata were extracted with 80% aqueous MeOH and the concentrates were partitioned into EtOAc, n-BuOH, and H₂O fractions. The repeated silica gel (SiO₂) and octadecyl silica gel column chromatographies for the EtOAc fraction led to isolation of one flavonol and one benzoyl compounds. The chemical structures of the compounds were respectively determined as melanoxetin (1) and protocatechuic acid methyl ester (2) based on spectroscopic analyses including NMR, IR, and MS. These two compounds were isolated for the first time from C. lanceolata flowers in this study. All fractions and the isolated compounds were evaluated for 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activities.

• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.942-947
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• 2001

Thickness dependence of orientation on piezoelectric and electrical properties was investigated by PZT (52/48) films by diol based sol-gel method. The thickness of each layer by spinning at one time was $0.2{\mu}m$ and crack-free films could be successfully deposited on 4 inches Pt/Ti/$SiO_2$/Si substrates by 0.5 mol solutions in the range from $0.2{\mu}m$ to $3.8{\mu}m$. Excellent P-E hysteresis curves were achieved, which were attributed to the well-densified PZT films and columnar grain without pores or any defects between interlayers. The (111) preferred orientation of films were shown in the range of thickness below $1{\mu}m$. As the thickness increased, the (111) preferred orientation disappeared from $1{\mu}m$ to $3{\mu}m$ region, and the orientation of films became random above $3{\mu}m$. Dielectric constants and longitudinal piezoelectric coefficient, $d_{33}$, measured by pneumatic method were saturated around the value of about 1400 and 300 pC/N respectively above the thickness of $1{\mu}m$.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1067-1074
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• 1995

Reaction of arachno-S2B7H8- with either THF or 1,2-dimethoxyethane upon refluxing condition results in the formation of the previously known compound hypho-S2B7H10-. Protonation of hypho-S2B7H10- with HCl/Et2O generates hypho-2,5-S2B7H11 in good yield. This hypho-S2B7H10- anion has been employed to generate a series of new nido-, arachno-, and hypho-metalladithiaborane clusters. Reaction of the anion with Cp(CO)2FeCl results in direct metal insertion and the formation of a complex containing the general formula (η5-C5H5)FeS2B7H8. Spectroscopic studies of nido-6-CpFe-7,9-S2B7H8 Ⅰ demonstrated that compound Ⅰ was shown to have an nido-type cage geometry derived from an octadecahedron missing one vertex, with the iron atom occupying the three-coordinate 6-position in the cage and the two sulfurs occupying positions on the open face of the cage. Reaction of hypho-S2B7H10- with CoCl2/Li+[C5H5]- gave the previously known complex arachno-7-CpCo-6,8-S2B6H8 Ⅱ. Also, the reaction of the anion with [Cp*RhCl2]2 gave the complex arachno-7-Cp*Rh-6,8-S2B6H8 Ⅲ, the structure of which was shown to be that of complex Ⅱ. The similarity of the NMR spectra of Ⅱ and Ⅲ suggest that Ⅲ adopts cage structure similar to that previously confirmed for Ⅱ. A series of 9-vertex hypho clusters in which the sulfur atoms are bridged by different species isoelectronic with a BH3 unit, such as HMn(CO)4 or SiR2 have been prepared. Compounds Ⅳ,Ⅴ and Ⅵ are each 2n+4 skeletal electron systems and would be expected according to skeletal electron counting theory to adopt hypho-type polyhedral structures derived from an icosahedron missing three vertices. The complex hypho-1-(CO)4Mn-2,5-S2B6H9 Ⅳ was obtained by the reaction of the anion with (CO)5MnBr and has been shown from spectroscopic data to consist of a (CO)4Mn fragment bound to the two sulfur atoms S2 and S5 of hypho-S2B7H10-. Also, similar hypho-type complexes hypho-1-R2Si-2,5-S2B6H8 (R=CH3 Ⅴ, R=C6H5 Ⅵ) have been prepared from the reaction of hypho-S2B7H10- with R2SiHCl.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.235-241
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• 2003

The effect of ultraviolet (UV) radiation on the characteristics of algae-derived dissolved organic matter (DOM) was examined by comparing the biodegradability and DOM fraction distribution of algal DOM before and after UV exposure. Algal DOM from two axenic cultures of Microcystis aeruginosa and Oscillatoria agardhii were irradiated for 24 h at a UV intensity of 42 W/$m^2$. A complete degradation of algal DOM during the UV exposure did not occur, remaining at constant concentrations of dissolved organic carbon(DOC). After UV exposure, however, microbial degradations were reduced by 17% in M. aeruginosa and 53% in O. agardhii, respectively, and decomposition rates also were two times lower in UV exposed algal DOM. In addition, the chemical compositions of algal DOM altered substantially after UV radiation exposure. The proportions of hydrophilic bases (HiB; protein-like DOM) decreased considerably in both algal DOM sources after UV exposure (16.8% and 20.0% of DOM, respectively), whereas those of hydrophilic acids (HiA; carboxylic acids-like DOM) increased as much as the decrease of the HiB fraction. Capillary ion electrophoresis (CE) analysis showed that several carboxylic acids increased significantly after UV exposure, further confirming an increase in HiA fractions. The results of this study clearly indicate that algal DOM can be changed in its chemical composition as well as biodegradability without complete degradation by UV radiation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.126-135
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• 1987

The physical properties, coliform groups, and nutrients were investigated to evaluate the sanitary Quality of the environmental water at Chinju area from May to October, 1986. The results were as follows : The pH ranged from 5.4 to 7.8 : water temperature ranged from 12.0 to $30.3^{\circ}C$ : electrical conductivity ranged from $0.51\times10^2\;to\;8.095\times10^2\mu\mho/cm$; chloride ion ranged from 3.6 to 126.8 mg/l, respectively. Especially, the concentration of the chloride ion at St.9 was 109mg/l which was higher than those of others. The $NO_3^--N$ ranged from 0.2336 to 14.1648 mg/l and the mean value was 5.4774 mg/l, the concentration of $NO_3^--N$ at St. 2 was higher as 40 times than that of St.4. The $PO_4^{3-}-P$ ranged from 0.0013 to 0.8315 mg/l, and the mean value was 0.0745 mg/l, the concentration of$PO_4^{3-}-P$ at St.8 was higher than that of others. The $SiO_2-Si$ ranged 1.7 to 15.28 mg/1 and the mean value was 5.81 mg/l. The value of St.8 and St.9 were higher than those of other stations but this value were lower $10\~13\;mg/l$ than the criterion for drinking water as 50 mg/l. The bacterial density of the spring waters ranged 9.1 to 4,600/100 ml (geometric mean : 205/100 ml) for total coliform 0 to 4s0/100 ml and 28.2/100 ml for fecal coliform. Composition of coliform was $38.2\%$ Escherichia coli, $25\%$ Entrobacter aerogenes, $13.2\%$ Citrobecter freundii and the others.

• Proceedings of the Safety Management and Science Conference
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• 2007.04a
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• pp.471-476
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• 2007

본 논문의 목적은 과거의 산업 포트폴리오 수익률이 확률추세로부터 어떻게 전체 주식시장과 두 가지 거시경제 변수인 경기동행지수와 산업생산 등을 예측할 수 있는 지를 알아보는 데에 있다. 이를 위하여 본 연구에서는 연구모형을 설정한 후 세 가지 검정절차를 제시하고 이를 실증적으로 분석하였다. 당월의 전체 주식시장 수익률은 과거의 시차를 지닌 특정 산업부문 포트폴리오 수익률에 대하여 양(+)의 상관관계를 유지하고 있다는 '예측 1'과 전체 주식시장의 수익률은 특정 산업부문의 수익률에 대하여 선행성을 지닐 수 없다는 '예측 2'에 대한 검정 결과는 '예측 1'과 '예측 2'가 지지되고 있음을 파악할 수 있었다. 그리고 산업별 포트폴리오 수익률과 거시경제변수 간의 높은 상관관계를 토대로 하여 전체주식시장 수익률 예측을 가능하게 하는 업종 정보의 점진적 확산 현상이 발생하게 되는가를 검토하기 위하여 각 산업들의 포트폴리오 수익률과 전체 주식시장 수익률이 VAR모형을 토대로 볼 경우 Granger 인과관계를 갖고 있는 지를 분석하였다. 분석결과 21개 업종은 각 산업별 포트폴리오 수익률이 전체 주식시장 수익률을 5% 수준에서 통계적으로 유의한 영향을 주고 있음을 알 수 있었다. 이들 21개의 산업별 포트폴리오 수익률은 경제적으로도 중요한 의미를 지니고 있어 산업제품의 가격 상승과 하락이 경제에 미치는 영향을 파악할 수 있다. 특히 음료 업종에서 전체 주식시장 수익률과 상호간의 인과성을 나타내었으며, 인터넷과 화장품 업종에서는 전체 주식시장 수익률이 이들 업종에 대하여 일방적인 영향을 보이고 있음을 알 수 있었다.>$mgN\;{\cdot}\;L^{-1}$ 및 0.000-0.804 $mgN\;{\cdot}\;L^{-1}$이였다. 규소농도는 0.0-6.2 $mgSi\;{\cdot}\;L^{-1}$의 범위로 3-5월에 매우 낮았으며, 계절적인 변화가 뚜렷히 나타났다. 저질의 입자는 0-125인 silt및 coarse silt로 이루어져 있으며, COD는 51.4-116.9 $mgO_2\;{\cdot}\;gdw^{-1}$로 평균 93.0 $mgO_2\;{\cdot}\;gdw^{-1}$ 이였다. 저질내의 TP및 TN의 농도는 각각 0.04-1.46 $mgP\;{\cdot}\;gdw^{-1}$ 및 0.12-1.03 $mgN\;{\cdot}\;gdw^{-1}$이었다. 표층의 엽록소 a의 정점별 평균값은 정점 1, 2 및 3에서 각각 15.6, 15.2 및 16.0 $mg\;{\cdot}\;m^{-3}$으로 유사하였다. 식물플랑크톤은 총 49종이 출현하였으며, 생물량은 50-23, 350 cells ${\cdot}\;mL^{-1}$로 2001년 9월에 가장 많았다. 이 시기의 우점종은 녹조류인 Schroederia judayi이였으며, 생물량은 20,417 cells ${\cdot}\;mL^{-1}$이였다. 송지호의 수질을 개선하기 위해서는 인위적으로 화학성층을 파괴시켜 심충에 용존산소를 공급시켜야 할 것으로 판단되며, 모래톱으로 인해 막혀져 있는 해수

• Journal of the Korean Applied Science and Technology
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• v.22 no.1
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• pp.28-34
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• 2005

The structure of a carbon monoxide sorption complex of dehydrated fully $Ca^{2+}$-exchanged zeolite X, $|Ca_{46}(CO)_{27}|[Si_{100}Al_{92}O_{384}]$-FAU, has been determined in the cubic space group $Fd\;{\overline{3}}$ at $21^{\circ}C$ (a = 24.970(4) ) by single-crystal X-ray diffraction techniques. The crystal was prepared by ion exchange in a flowing stream of 0.05 M aqueous ${Ca(NO_3)_2}$ for three days, followed by dehydration at $400^{\circ}C$ and $2{\times}10^{-6}$ Torr for two days, and exposure to 100 Torr of zeolitically dry carbon monoxide gas at $21^{\circ}C$. The structure was determined in this atmosphere and was refined, using the 356 reflections for which $F_o$ > $4{\sigma}(F_o)$, to the final error indices $R_1$ = 0.059 and $wR_2$ = 0.087. In this structure, $Ca^{2+}$ ions occupy three crystallographic sites. Sixteen $Ca^{2+}$ ions fill the octahedral site I at the centers of hexagonal prisms (Ca-O = 2.415(7) ${\AA}$). The remaining 30 $Ca^{2+}$ ions are found at two nonequivalent sites II (in the supercages) with occupancies of 3 and 27 ions. Each of these $Ca^{2+}$ ions coordinates to three framework oxygens, either at 2.276(10) or 2.298(8) ${\AA}$, respectively. Twenty-seven carbon monoxide molecules have been sorbed per unit cell, three per supercage. Each coordinates to one of the latter 16 site-II $Ca^{2+}$ ions: C-Ca = 2.72(8) ${\AA}$. The imprecisely determined N-C bond length, 1.26(14) ${\AA}$, differs insignificantly from that in carbon monoxide(g), 1.13 ${\AA}$.

• Analytical Science and Technology
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• v.26 no.4
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• pp.228-234
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• 2013

Methamphetamine is an amine-containing illegal drug and is distributed unlawfully in South Korea. Finding a rapid, convenient and semi-quantitative determination method for methamphetamine is a very important issue in the area of forensic drug testing. As an effort to develop new screening method, the reactions between three organic compounds which are structurally similar to methamphetamine and N-(9-fluorenylmethoxycarbonyloxy) succinimide (FMOC-NHS) were performed on silica gel ($SiO_2$) TLC plates. Three reference compounds were synthesized and used for the identification, comparison and study of the limit of detection (LOD) of the products obtained from a direct reaction on a TLC plate. As a result, FMOC-NHS as a derivatization reagent generated compounds containing highly UV-active functional groups on the TLC plate after reacting with primary- and secondary amines. In the experiment 2D the LOD of amines was in the range of 0.045 and 0.01 mg/mL ($2{\mu}L/spot$), and in 1D the LOD was in the range of 0.002 and 0.007 mg/mL ($2{\mu}L/spot$). The LODs of the compounds tested were dependent on the concentration of the derivatizing reagent.

• Journal of the Korean Ceramic Society
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• v.52 no.4
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• pp.229-233
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• 2015

Currently, the majority of commercial white LEDs are phosphor converted LEDs made of a blue-emitting chip and YAG yellow phosphor dispersed in organic silicone. However, silicone in high-power devices results in long-term performance problems such as reacting with water, color transition, and shrinkage by heat. Additionally, yellow phosphor is not applicable to warm white LEDs that require a low CCT and high CRI. To solve these problems, mixing of green phosphor, red phosphor and glass, which are stable in high temperatures, is common a production method for high-power warm white LEDs. In this study, we fabricated conversion lenses with LUAG green phosphor, SCASN red phosphor and low-softening point glass for high-power warm white LEDs. Conversion lenses can be well controlled through the phosphor content and heat treatment temperature. Therefore, when the green phosphor content was increased, the CRI and luminance efficiency gradually intensified. Moreover, using high heat treatment temperatures, the fabricated conversion lenses had a high CRI and low luminance efficiency. Thus, the fabricated conversion lenses with green and red phosphor below 90 wt% and 10 wt% with a sintering temperature of $500^{\circ}C$ had the best optical properties. The measured values for the CCT, CRI and luminance efficiency were 3200 K, 80, and 85 lm/w.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.134-140
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• 2007

Optical structure of $V_{2}O_{5}$ thin films were analyzed and confirmed, the films were deposited in oxygen partial pressure 0% and 10% by RF magnetron sputtering system. Measurements of the elliptic constants were made in the range of $0.75{\sim}4.0\;eV$ by using phase modulated spectroscopic ellipsometer. The elliptic constants of the thin films were analyze by Double Amorphous dispersion relation. The calculated n, k spectra of $V_{2}O_{5}$ layer were obtained over the range of $0.75{\sim}4.0\;eV$ photon energy. SEM and XRD measurements were also made to validate the ellipsometric analysis and they give good agreement with the structural properties of the films. It was found that optical structure of the $V_{2}O_{5}$ layer has a 3 phase(roughness/film/substrate) and optical absorption properties are greatly depend on the partial pressure of the oxygen.