• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1255-1258
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• 2008

New phosphors that enable the 3D application of PDP have been developed The decay times of $Y_3Al_5O_{12}:Ce^{3+}$, $(Y,Gd)Al_3(BO_3)_4:Tb^{3+}$ and $(Y,Gd)_2O_3:Eu^{3+}$ were extremely shorter than those of conventional PDP phosphors. The color coordinates and intensities of the phosphors were also suitable for PDP For the first time in PDP industry, 3D/2D switchable PDP has been commercially available by adopting the phosphors.

• Tuberculosis and Respiratory Diseases
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• 제68권5호
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• pp.280-285
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• 2010

Background: $QuantiFERON^{(R)}$-TB Gold In Tube (QFT-G IT) has been used for diagnosing latent tuberculosis infection and active tuberculosis (TB) since 2007. However, there has not been enough data on QFT-G IT for universal use in children. In this study, we evaluated the clinical usefulness of the QFT-G IT in pediatric practice. Methods: We retrospectively reviewed the clinical records of 70 patients younger than 18 years of age who had taken QFT-G IT and had a tuberculin skin test (TST) between July 2007 and July 2009 at Wonju Christian Hospital. The subjects were divided into two groups, asymptomatic TB exposure group and disease group. Four patients who were taking immunosuppressants during the study period were excluded. Results: A total of 66 immunocompetent children were included in this study. Among 27 asymptomatic children who had contact histories of TB, 6 (22.2%) were found to be positive by QFT-G IT. Eleven (40.7%) and 5 (18.5%) children were found to be positive by TST with cutoff values of ${\geq}5mm$ and ${\geq}10mm$, respectively. Agreement was fair to good between QFT-G IT and TST (${\kappa}=0.59$: cutoff value ${\geq}5mm$, ${\kappa}=0.7$: cutoff value ${\geq}10mm$). In disease group, 14 patients (35.9%) were diagnosed with active tuberculosis, 8/14 (57.1%) were positive on TST and 9/14 (64.3%) on QFT-G IT. The positive rate of acid-fast bacilli smear, TB-polymerase chain reaction, and culture for tuberculosis was 11% (1/9), 27.3% (3/11) and 33.3% (3/9), respectively. Conclusion: Our data support that the QFT-G IT can be used as an additional diagnostic tool for latent and active tuberculosis infection in children.

• 대한원격탐사학회지
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• 제38권5_3호
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• pp.863-872
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• 2022

희토류 원소(rare earth elements, REEs)는 유사한 물리적·화학적 성질을 가지고 있어 지질학적 환경변화를 해석하는 유용한 도구로 사용되고 있다. 이번 연구에서는 2018년 1월 한 달간 북경 및 광주광역시에서 포집된 초미세먼지 내 희토류 원소의 특성을 비교하였다. 북경 및 광주 초미세먼지 내 총 희토류 원소 농도는 북경이 광주보다 약 16배 높았으며 두 지역 모두 경희토류가 중희토류에 비해 8-10배 이상 부화되었다. Post Archean Australian Shale (PAAS) 표준화 분포 패턴을 통해 북경과 광주 초미세먼지는 Eu, Tb, Er이 다른 원소보다 부화된 양상을 보였고, 두 지역 모두 양(+)의 Eu 이상치와 음(-)의 Ce 이상치가 나타났다. 희토류 원소 간 상관관계를 통해 북경과 광주의 초미세먼지는 중국 사막 및 황토 고원과 북경 주변 도시(Zhangbei, Fengning, Miyun)의 영향을 받는 것으로 나타났다. 이번 연구를 통해 초미세먼지 내 희토류 원소는 국가 간 미세먼지의 차이를 밝힐 수 있는 중요한 지시자로 활용될 수 있으며, 국내 미세먼지 기원 및 이동에 대한 보다 명확한 정보를 제공하는 유용한 도구로 활용될 것으로 판단된다.

• 한국재료학회지
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• 제30권8호
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• pp.406-412
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• 2020

SrMoO₄:RE³⁺ (RE=Dy, Sm, Tb, Eu, Dy/Sm) phosphors are prepared by co-precipitation method. The effects of the type and the molar ratio of activator ions on the structural, morphological, and optical properties of the phosphor particles are investigated. X-ray diffraction data reveal that all the phosphors have a tetragonal system with a main (112) diffraction peak. The emission spectra of the SrMoO₄ phosphors doped with several activator ions indicate different multicolor emissions: strong yellow-emitting light at 573 nm for Dy³⁺, red light at 643 nm for Sm³⁺, green light at 545 nm for Tb³⁺, and reddish orange light at 614 nm for Eu³⁺ activator ions. The Dy³⁺ singly-doped SrMoO₄ phosphor shows two dominant emission peaks at 479 and 573 nm corresponding to the ⁴F_9/2→⁶H_15/2 magnetic dipole transition and ⁴F_9/2→⁶H_13/2 electric dipole transition, respectively. For Dy³⁺ and Sm³⁺ doubly-doped SrMoO₄ phosphors, two kinds of emission peaks are observed. The two emission peaks at 479 and 573 nm are attributed to ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 transitions of Dy³⁺ and two emission bands centered at 599 and 643 nm are ascribed to ⁴G_5/2→⁶H_7/2 and ⁴G_5/2→⁶H_9/2 transitions of Sm³⁺. As the concentration of Sm³⁺ increases from 1 to 5 mol%, the intensities of the emission bands of Dy³⁺ gradually decrease; those of Sm³⁺ slowly increase and reach maxima at 5 mol% of Sm³⁺ ions, and then rapidly decrease with increasing molar ratio of Sm³⁺ ions due to the concentration quenching effect. Fluorescent security inks based on as-prepared phosphors are synthesized and designed to demonstrate an anti-counterfeiting application.

• 자원리싸이클링
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• 제29권3호
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• pp.61-74
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• 2020

본 연구에서는 폐형광등 처리 공정의 경제성 확보를 위하여 수행되었으며, 폐형광등 유리의 글래스비드용 원료로서의 사용 가능성, 폐형광체 분말로부터 희토류의 침출, 희토류 침출액으로부터 희토류의 용매추출 가능성 등을 검토하였다. 폐형광체는 산화이트륨 28.9%, 산화세륨이 3.46%, 산화유로퓸 1.95%, 산화터븀 1.76%, 산화란탄 1.43% 순으로 함유되어 있어 회수 및 정제 시 경제성이 충분할 것으로 판단되었다. 폐형광등 유리를 사용하여 글래스비드를 시험 생산 한 결과 그 생산수율과 품질이 우수하여 폐형광등 유리를 글래스비드용 원료로 사용할 수 있을 것으로 판단되었다. 소다배소한 폐형광체를 수침출하면 알루미늄과 규소성분 및 잔류 탄산나트륨 등이 용해하며, 이 수용액에 탄산가스를 불어 넣어 pH를 7 정도로 떨어뜨리면 NaAl₂(CO₃)(OH)₂와 SiO₂ 등이 침전하였다. 자이렌을 희석제로 사용하는 cyanex272-hydrochloric acid, cyanex272-sulfuric acid, D2EHPA-hydrochloric acid, D2EHPA-sulfuric acid, lonquest290-hydrochloric acid, lonquest290-sulfuric acid, p507-hydrochloric acid 조합의 용매추출에서 Y, Eu, Ce, La, Tb의 추출률이 100%에 가깝다. 그러나 동일 조건에서의 원소별 추출률의 차이, 즉 선택성은 16% 이하이다.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 하계학술발표회 논문집
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• pp.147-148
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• 2008

• 한국광물학회지
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• 제32권2호
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• pp.127-143
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• 2019

철마산 일대의 지질은 하부로부터 선캠브리아기의 소근리층, 화강암질편마암, 엽리상 흑운모화강암, 엽리상 운모화강암, 염기성암맥 및 산성암맥으로 구성된다. 이 일대의 희토류 광화작용은 화강암질편마암과 엽리상 운모화강암에서 관찰된다. 이들 암석에서 소량 희토류 원소 및 토륨을 함유한 광물들은 저어콘($Y_2O_3$ 0.00~1.18 wt.%, $Gd_2O_3$ 0.00~0.59 wt.%, $Er_2O_3$ 0.00~0.22 wt.%, $Yb_2O_3$ 0.00~0.34 wt.%, $Lu_2O_3$ 0.00~0.48 wt.%, $ThO_2$ 0.00~0.33 wt.%), 토리아나이트($Nd_2O_3$ 0.00~0.24 wt.%, $Lu_2O_3$ 0.00~0.26 wt.%), 베르시에린($La_2O_3$ 0.04~0.26 wt.%, $Nd_2O_3$ 0.00~0.20 wt.%, $Tb_2O_3$ 0.04~0.12 wt.%, $Dy_2O_3$ 0.17~0.26 wt.%, $Er_2O_3$ 0.33~0.44 wt.%, $Lu_2O_3$ 0.00~0.19 wt.%, $ThO_2$ 0.61~0.93 wt.%), 녹니석($La_2O_3$ 0.44~0.68 wt.%, $Ce_2O_3$ 0.12~0.13 wt.%, $Nd_2O_3$ 0.31~0.44 wt.%, $Eu_2O_3$ 0.03~0.08 wt.%, $Dy_2O_3$ 0.09~0.21 wt.%, $Ho_2O_3$ 0.04~0.14 wt.%, $Er_2O_3$ 0.18~0.32 wt.%, $Lu_2O_3$ 0.07~0.21 wt.%, $ThO_2$ 0.00~0.97 wt.%), 흑운모($Nd_2O_3$ 0.02~0.08 wt.%, $Gd_2O_3$ 0.07~0.08 wt.%, $Tb_2O_3$ 0.02~0.07 wt.%, $Dy_2O_3$ 0.35~0.43 wt.%, $Ho_2O_3$ 0.15~0.26 wt.%, $Er_2O_3$ 0.24~0.28 wt.%, $Yb_2O_3$ 0.06~0.18 wt.%, $ThO_2$ 0.00~0.12 wt.%), 정장석($Dy_2O_3$ 0.05~0.12 wt.%, $Ho_2O_3$ 0.05~0.06 wt.%, $Er_2O_3$ 0.28 wt.%, $Yb_2O_3$ 0.06~0.12 wt.%) 및 사장석($Ho_2O_3$ 0.01~0.03 wt.%, $Er_2O_3$ 0.10~0.27 wt.%, $ThO_2$ 0.11~0.13 wt.%)이며 희토류 광물로는 바스트나사이트와 퍼구소나이트이다. 희토류 광물들은 주로 장석류, 운모류, 저어콘, 인회석 및 티탄철석의 간극을 따라 산출된다. 따라서 철마산 일대의 희토류 광화작용 산물인 바스트나사이트와 퍼구소나이트는 화강암질편마암과 엽리상 운모화강암의 형성 시 희토류 원소 및 토륨이 구성광물 내에 소량 함유되어 있었으며 그후 계속된 화성활동 및 변성작용에 의하여 기존 광물 내에 함유되어 있던 희토류 원소가 재 농집에 의해 형성된 것으로 생각된다.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2774-2780
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• 2013

Two new isostructural dinuclear complexes, $Ln_2(4-cpa)_6(bpy)_2$ (Ln = Eu (1); Tb (2), 4-cpa = 4-chlorophenylacetate, bpy = 2,2'-bipyridine), have been hydrothermally synthesized and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffraction and single-crystal X-ray diffraction. The lanthanide ions are bridged by two bidentate and two terdentate carboxylate groups to give centrosymmetric dimers with $Ln{\cdots}Ln$ separations of 3.967(2) and 3.956(3) ${\AA}$, respectively. Each metal atom is nine-coordinate and exhibits a distorted tricapped trigonal prismatic geometry. Three-dimensional fluorescence spectra show that both 1 and 2 emit bright red and green luminescence at room temperature, with long lifetimes of up to 0.369 ms (at 614 nm) and 0.432 ms (at 543 nm), respectively. Moreover, poor luminescence efficiency has been noted for complex 2. The 4-Hcpa ligand and complexes 1-2 have been screened for their phytogrowth-inhibitory activities against Brassica napus L. and Echinochloa crusgalli L., and the results are compared with the activity of quizalofop-P-ethyl.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.292-292
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• 2016

Transition metal dichalcogenides (TMDs) with a two-dimensional layered structure have been considered highly promising materials for next-generation flexible, wearable, stretchable and transparent devices due to their unique physical, electrical and optical properties. Recent studies on TMD devices have focused on developing a suitable doping technique because precise control of the threshold voltage ($V_{TH}$) and the number of tightly-bound trions are required to achieve high performance electronic and optoelectronic devices, respectively. In particular, it is critical to develop an ultra-low level doping technique for the proper design and optimization of TMD-based devices because high level doping (about $10^{12}cm^{-2}$) causes TMD to act as a near-metallic layer. However, it is difficult to apply an ion implantation technique to TMD materials due to crystal damage that occurs during the implantation process. Although safe doping techniques have recently been developed, most of the previous TMD doping techniques presented very high doping levels of ${\sim}10^{12}cm^{-2}$. Recently, low-level n- and p-doping of TMD materials was achieved using cesium carbonate ($Cs_2CO_3$), octadecyltrichlorosilane (OTS), and M-DNA, but further studies are needed to reduce the doping level down to an intrinsic level. Here, we propose a novel DNA-based doping method on $MoS_2$ and $WSe_2$ films, which enables ultra-low n- and p-doping control and allows for proper adjustments in device performance. This is achieved by selecting and/or combining different types of divalent metal and trivalent lanthanide (Ln) ions on DNA nanostructures. The available n-doping range (${\Delta}n$) on the $MoS_2$ by Ln-DNA (DNA functionalized by trivalent Ln ions) is between $6{\times}10^9cm^{-2}$ and $2.6{\times}10^{10}cm^{-2}$, which is even lower than that provided by pristine DNA (${\sim}6.4{\times}10^{10}cm^{-2}$). The p-doping change (${\Delta}p$) on $WSe_2$ by Ln-DNA is adjusted between $-1.0{\times}10^{10}cm^{-2}$ and $-2.4{\times}10^{10}cm^{-2}$. In the case of Co-DNA (DNA functionalized by both divalent metal and trivalent Ln ions) doping where $Eu^{3+}$ or $Gd^{3+}$ ions were incorporated, a light p-doping phenomenon is observed on $MoS_2$ and $WSe_2$ (respectively, negative ${\Delta}n$ below $-9{\times}10^9cm^{-2}$ and positive ${\Delta}p$ above $1.4{\times}10^{10}cm^{-2}$) because the added $Cu^{2+}$ ions probably reduce the strength of negative charges in Ln-DNA. However, a light n-doping phenomenon (positive ${\Delta}n$ above $10^{10}cm^{-2}$ and negative ${\Delta}p$ below $-1.1{\times}10^{10}cm^{-2}$) occurs in the TMD devices doped by Co-DNA with $Tb^{3+}$ or $Er^{3+}$ ions. A significant (factor of ~5) increase in field-effect mobility is also observed on the $MoS_2$ and $WSe_2$ devices, which are, respectively, doped by $Tb^{3+}$-based Co-DNA (n-doping) and $Gd^{3+}$-based Co-DNA (p-doping), due to the reduction of effective electron and hole barrier heights after the doping. In terms of optoelectronic device performance (photoresponsivity and detectivity), the $Tb^{3+}$ or $Er^{3+}$-Co-DNA (n-doping) and the $Eu^{3+}$ or $Gd^{3+}$-Co-DNA (p-doping) improve the $MoS_2$ and $WSe_2$ photodetectors, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.290.1-290.1
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• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.