• 대한화학회지
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• 제50권2호
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• pp.137-140
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• 2006

Eu2+를 활성제로 한(Sr,Ba)2Ga2SiO7 녹색 형광체를 일반적인 고상 반응으로 합성하였고, 그 합성된 형광체의 광발광 특성을 연구하였다. 형광체 제조 시, 마노유발에서 보다 효과적인 혼합을 위하여 아세톤을 사용하여 혼합하였다. 또한 25%H2/75%N2의 혼합기체를 이용한 환원조건에서 단순한 공정으로 형광체를 합성하였다. 이 형광체는 405 nm의 여기 파장하에서 효율적으로 발광되는 녹색 밴드(513 nm)를 갖고 있기 때문에 백색 LED(Light Emitting Diode)램프에 응용할 수 있다.

• Bulletin of the Korean Chemical Society
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• 제17권9호
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• pp.790-793
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• 1996

The azacrown compound, 1,7-dioxa-4,10,13-triazacyclopentadecane-N,N',N"-tri(methyl-acetic acid)(N3O2-tri(methylacetic acid)) was synthesized by modified procedure of Krespan. Potentiometric method has been used to determine the protonation constants of N3O2-tri(methylacetic acid) and stability constants of complexes on the divalent transition metal ions (Co2+, Ni2+, Cu2+, and Zn2+) and trivalent metal ions (Ce3+, Eu3+, Gd3+, and Yb3+) with N3O2-tri(methylacetic acid). The stability constants for the complexes of the divalent transition metal ions studied in the present work with N3O2-tri(methylacetic acid) were 11.4 for Co2+, 11.63 for Ni2+, 13.51 for Cu2+, and 11.65 for Zn2+, respectively. Thus, the order of the stability constants for complexes on the transition metal ions with N3O2-tri(methylacetic acid) was shown Co2+ < Ni2+ < Cu2+ > Zn2+ as same as the order of Irving-Williams series. The stability constants of Ce3+, Eu3+, Gd3+, and Yb3+ trivalent lanthanide metal ion complexes of N3O2-tri(methylacetic acid) were, respectively, 11.26 for Ce3+, 11.56 for Eu3+, 11.49 for Gd3+, and 11.80 for Yb3+. The values of the stability constants on trivalent metal ions with the ligand are increasing according to increase atomic number, due to increase acidity. But the value of stability constant of Gd3+ ion is less than the value of Eu3+ ion. This disordered behavior is also reported by Moeller.

• Bulletin of the Korean Chemical Society
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• 제18권1호
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• pp.75-80
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• 1997

Preparation and properties of Eu(hfa)3·L (Hhfa = hexafluoroacetylacetone, L = bis(2-methoxyethyl)ether, diglyme, and 2, 2':6', 2"-terpyridine, tpy), which are potential CVD precursors for europium, were investigated. The reaction of the Eu2O3 with Hhfa in the presence of tridentate neutral ligand yielded the nine-coordinated Eu(hfa)3·L. Eu(hfa)3·diglyme is air- and moisture-stable and most importantly has good volatility and thermal stability. Eu(hfa)3·tpy shows no sublime intact. The complex Eu(hfa)3·diglyme has been characterized by an X-ray structure determination; monoclinic P21/n, a=10.252(1), b=16.051(6), c=19.392(8) Å, β=96.10(2)°, V=3173(2) Å3. The europium atom in Eu(hfa)3·diglyme adopts a square-antiprismatic geometry with the ninth coordinating oxygen atom capping one of the square faces. All the adducts have been characterized by IR, TGA/DTA.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.654-657
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• 1995

A series of excitation spectra (7Fo→5Do transition) of Eu(Ⅲ) ion in aqueous solution ([Eu(Ⅲ)]=1.12 × 10-2 mol L-1; pH 1.0 to 7.0) were obtained under CO2 free atmosphere using a pulsed tunable dye laser system. The broad and low intensity spectra (peak maximum: 578.89 nm) showed that the trivalent ion (Eu3+) underwent a low degree of hydrolysis at pH below 6.0. Eu(Ⅲ) hydroxo complex formation seemed more significant at pH above 6.0, shown by the occurrence of intense new peak at 578.63 nm. The spectra of those solutions prepared in N2 atmosphere showed no signs of the presence of interfering carbonate species. The Eu(Ⅲ) hydroxo complex formation was not observed when complexation studies between Eu(Ⅲ) ion and weak organic acids (e.g. glutarate and diglycolate) were conducted at pH 6.0 or below.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(2)
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• pp.301-306
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• 1997

추출제 di-(2-ethylhexyl)phosphoric acid건의 Zr 염으로 $^{241}$Am 및 $^{152}$Eu의 상호분리를 위한 용매추출공정에 대한 화학적 특성을 규명하였다. 추출공정에서 질산농도 0.5M, Zr 농도 8.7g/L, 추출제 HDEHP/n-dodecane 농도가 1M 일때 Am 및 Eu은 각각 92.3%와 99.1%가 추출되었으며, Zr 농도에 비례하여 Am, Eu의 추출율이 증가하는 상승효과를 나타내었다. pH가 3인 0.05M DTPA와 1M lactic acid 혼합 역추출용액으로 Am을 선택적으로 역추출한 결과 Am의 역추출율은 38.1% 이며, 이때 Am과 Eu의 상호분리비는 14.2 였다. 그리고 유기상에 남아 있는 Eu은 6M 질산용액으로 역추출한 결과 94.4%의 Eu가 역추출되었다.

• 한국세라믹학회지
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• 제54권3호
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• pp.217-221
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• 2017

Improvement studies of existing phosphors are needed for use in light emitting diodes (LEDs). Among the phosphors discovered recently, the SLA ($SrLiAl_3N_4:Eu^{2+}$) is a phosphor that has a narrow width. It is now known as a good red phosphor that meets the industry's needs for warm white (color temperature ranging from 2700 to 4000 K) and high CRI (> 80). However, SLA phosphors are obtained from difficult synthetic methods. All commercially available phosphors should be derived from the general solid state synthesis method. The phosphors produced by difficult synthetic methods will inevitably fall out of price competitiveness and will be scrapped. This study succeeded in synthesizing SLA ($SrLiAl_3N_4:Eu^{2+}$) phosphors by using a general solid phase synthesis method based on the reaction energy obtained from DFT calculations. As a result, we found an optimal solid state synthesis method for SLA phosphors.

• 통상정보연구
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• 제9권2호
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• pp.161-182
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• 2007

The objective of this paper is to examine the competitiveness of Korean export firms in EU market. In this study, market share index, RCA index, trade specialization index, and market competitiveness index were used as an analytical tool. On the market share index, Korea had a large market share in the SITC section 7(machinery and transport equipment) market in EU. On the RCA index, Korea appeared to have high export competitiveness in the electrical machinery, apparatus and appliances, n.e.s.(not elsewhere specified[stated]), and electrical parts thereof (77), travel goods, handbags and similar containers(83), textile yarn, fabrics, made-up articles, n.e.s., and related products(65), and iron and steel(67) division. On the trade specialization index, however, Korea appeared to tend to decline generally. On the market competitiveness index, Korea appeared to have competitive advantage in the iron and steel(67), machinery specialized for particular industries(72), office machines and automatic data-processing machines(75), electrical machinery, apparatus and appliances, n.e.s., and electrical parts thereof(77), road vehicles(78), and other transport equipment(79) division; but in 29 divisions, the index indicates that Korean firms' competitiveness was low. Finally, the authors discuss the implications of these findings and offer directions for future study.

• 패션비즈니스
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• 제16권1호
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• pp.26-40
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• 2012

The purpose of this study is to examine the fashion lifestyle variable of global consumers and to compare among US, Chinese and EU consumers. The data were collected in US(n=749), China(n=702) and EU(n=1083) from 2008 to 2010. For analysis, factor analysis, reliability analysis, K-means cluster analysis and chi-square analysis of SPSS 18.0 are used. The research results are as follow: First, it is shown that significant lifestyle factors of global fashion consumers are "adventure seeking", "fashion-oriented", "conspicuous consumption", "leadership", "brand-oriented", and "DIY". As a result of the cluster analysis of lifestyle types, four cross-national market segments are identified. These segments can be labeled as follows: "conservative fashion-oriented group", "passive consumer group", "neutral consumer group", "active fashion-oriented group". Second, findings also reveal that fashion lifestyle segments had meaningful differences between nationality and by year. Third, the US consumers tended to have conservative fashion-oriented lifestyle in 2008, however global consumers were changed to have active fashion lifestyle in 2010. This research will be useful to global brands in planning marketing strategies by offering specific information for global consumer fashion lifestyle.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 춘계학술발표회논문집(2)
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• pp.853-858
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• 1995

$^{152}$EU, $^{241}$Am 및 $^{241}$Np를 선정하여 추출제 di-(2-ethylhexyl)phosphoric acid (DEHPA)로 이들 세가지 핵종의 상호 분리공정에 대해 연구하였다. 추출공정에서 질산농도는 0.IM이고 추출 제DEHPA/n-dodecane 농도가 IM 일때, $^{152}$Eu 및 $^{241}$Am, $^{241}$Np 핵종 모두 99.9% 이상 추출되었다. $^{241}$Am 핵종의 역추출을 위한 제 1 역추출공정에서 역추출제인 0.05M di-ethylenetriamine pentaacetic acid (DTPA)와 1.5M 젖산 (lactic acid) 혼합용액의 pH가 3.6 일때 $^{152}$Eu과 $^{241}$Am의 상호분리비와 역추출율이 가장 좋았다. $^{152}$Eu의 역추출을 위한 제 2 역추출단계에서 역추출제인 질산용액의 최적농도는 6M이며, 이때 $^{152}$Eu은 99%가 역추출되었다.$^{241}$Np 핵종의 역추출을 위한 제 3 역추출공정에서 역추출제는 0.5M 옥살산이며, 이때 $^{241}$Np은 92%가 역추출되었다.

• 대한화학회지
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• 제50권3호
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• pp.237-242
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• 2006

LED는 고휘도 청색 칩의 개발로 인해 단순표시소자로만 이용되던 것이 다양한 분야의 발광소자로 적용되기 시작하였다. 특히, 최근에 InGaN 칩과 황색 형광체(YAG:Ce3+)를 이용한 방법이 많이 연구되어지고 있다. 하지만 이 방법은 2 파장을 이용한 것으로 색연지수가 낮은 단점을 지니며, 황색의 YAG:Ce3+ 형광체 이외에 450~470 nm의 여기 영역에서 효율적으로 발광하는 형광체가 거의 없다. 따라서 본 연구에서는 장파장 영역의 여기 특징을 지닌 thiogallate 형광체의 합성을 시도하였다. 그 중에 가장 잘 알려진 SrGa2S4:Eu2+ 형광체의 모체를 변화시켜 Sr2Ga2S5:Eu2+ 형광체를 합성하였으며, 발광특성을 조사하였다. 그리고 무해성과 제조 공정의 단순화를 위하여, 황화물질과 5 % H2/95 % N2 혼합 기체를 CS2와 H2S 가스 대신에 사용하였다. 이렇게 합성되어진 형광체는 550 nm의 발광 중심을 가지는 황색 형광체로서 300~500 nm에 이르는 넓은 여기원을 통한 발광이 가능하다. 그리고 YAG:Ce3+ 형광체와 비교해 볼 때 강도 면에서 110 % 이상을 보이며, UV 영역의 여기적 특성을 이용해 UV LED에도 응용이 가능하다.