Optical Characterization of Sm3+-doped Calcium-orthosilicate Phosphors Prepared using the Solid-State Reaction Method

하명규,정재선,한경림,배유리,김주성,김종필,K. S. Hong,양호순 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.12

Trivalent samarium-doped calcium-orthosilicate (Ca2SiO4:Sm3+) powder is synthesized by varyingSm2O3 amounts and the solid-state reaction method. X-ray diffraction patterns show that theobtained powders formed as orthorhombic-structured Ca2SiO4. Scanning electron microscope imagesshow that the powders have uniform structures of a few micrometers in size. Photophysicalfeatures are analyzed by taking absorption, excitation, and emission spectra. Emission spectraexhibit a red-orange luminescence from the 4G5/2 ! 6H7/2 transition of Sm3+ in all synthesizedphosphors. Both the physical and the optical properties show that Ca2SiO4:Sm3+ is an encouragingred-orange emitting phosphor applicable to photonics operating with near ultra-violet excitation.

Characterization and Optical Properties of Y2SiO5:Eu3+ Phosphors Prepared by Using the Reverse Micelle and the Sol-Gel Processes

하명규,한경림,정재선,배종성,정의덕,홍경수,배병서,배동식,양호순 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.6

Trivalent europium-ion-doped Y₂SiO₅ phosphors are synthesized by using the reverse micelle and the sol-gel processes. The crystallinity, morphology, and chemical states of the ions are characterized, and the photophysical properties are studied by taking absorption, excitation, and emission spectra for various concentrations of europium. Y₂SiO₅:Eu³⁺ is a red-emitting phosphor, has a higher efficiency for operation under near UV excitation, and may be a promising candidate for photonic applications.

Internal Transcribed Spacer와 5.8S ribosomal DNA의 염기서열 분석에 의한 Agaricus blazei와 근연종에 대한 계통분류학적인 연구

김기영,하명규,이태호,이재동 한국미생물학회 1999 미생물학회지 Vol.35 No.3

Molecular spslemaucs of Agaricus species was investigated on the base of the sequences of the internal transcribed spaceriITS) regions in ribosomal DNA (rDNA). The sequences of the ITS region in 5 species and two group of Agaricus genus were resolved. In the phylogenetic trees. the species generally divided inlo two subclusters, refered to here as the group I and group 11. The group I consisted of Agaricus blazei ATCC 76739, Agarictrs blazei species cultivated in Korean hmings. Ago/-icus anmensis IMSNU 32049 and Agaricus can~pestris VPI-OKM 25665. Between Agaricus blazei NCC 76739 and the Agaricus blazei species cultivated in Korean farmings had the variation in lhe 5 nucleotide on the ITS regions. These varieties were presumed the variation by the geographic and cultivated conditions. In addition the subgroup of group I was formed by Agaricus arvensis LMSNU 32049 and Agaricus carnpests VPI-OKM 25665. The group IT included Agnrictrs bispoms CH 3004 and Agaricus pocillotor DUKE-J 173. Agaricus 속의 계통분류학적 유연관계를 알아보기 위하여 Internal transcribed spacers 1,2, 와 5.8S rDNA 에 해당하는 부위를 PCR 기법으로 증폭하여 염기서열을 비교 조사하였다. 본 실험에 사용되어진 aGARICUS 속 5균주에 대한 염기서열을 분석한 결과, 이들 속은 크게 두 개의 군으로 분류되었다. 첫 번째 분류군은 aGARICUS BLAZEI atcc 76739, 현재 우리나라에서 배양중인 Agaricus blazei, agaricus arvensis IMSNU 32049, 그리고 Agaricus campestris VPI-OKM 25665로 이루어 졌다. 특히, Agaricus blazei ATCC 76739와 현재 우리나라 농가에서 배양중인 Agaricus blazeisms ITS 부위에서 5개의 염기서열에서 변이가 발견되었다. 이러한 변이는 지리적 또는 배양상의 변이로 인하여 특정염기서열에서 변이가 발생한 것으로 간주되므로 이들은 상호 동일종일 것으로 추정된다. 또한, Agaricus arvensis IMSNU 32049 와 Agaricus ampestris VPI-LKM 25665는 Agaricus blazei 하위 분류군을 형성하였다. 두 번째 분류군은 Agaricus bisporus CH 3004와 Agaricus pocillator DUKE-J 173 으로 이루어졌다.

Morphogenesis of Crystalline Carbonates Self-Assembled on Polyaminosiloxane

조은정,정의덕,하명규,안창원,김현주,이주운 한국고분자학회 2008 Macromolecular Research Vol.16 No.7

Direct conversion of citrus peel waste into hydroxymethylfurfural in ionic liquid by mediation of fluorinated metal catalysts

이영병,정정한,하명규,이진우,박석만,최영훈 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2

A new green technology was developed using citrus peel waste to produce hydroxymethylfurfual (HMF). FT-IR analysis of the waste showed 4 characteristic vibration modes (C–H, C–O, C–OH, and C55O/COOˉ),contributing to sugars. XRD and FESEM elucidated that the waste and its hydrolysate consist of highly amorphous clusters. HCl increased HMF yield by 1.4-fold. CrF3 increased its yield by 1.7-fold. At 0.2 of the stoichiometric ratio value, HMF yield was highest. The highest HMF yield was achieved in the reaction mixture of 4 g [OMIM]Cl, 1 mL ethyl acetate, 0.1 g CrF3, 5 mL 0.3 M HCl, and 0.5 g biomass.

Ribosomal DNA 의 Internal Transcribed Spacer (ITS) 부위의 염기서열분석에 의한 Phellinus 속의 계통분석에 관한 연구

이태호,이재동,김기영,정지원,하명규 한국균학회 1999 韓國菌學會誌 Vol.27 No.2

This study was carried out to identify the phylogenetic relationship among Phellinus species by comparing the DNA sequences of the 5.8S ribosomal DNA (rDNA) and the internal transcribed spacers (ITSs), ITS1 and ITS2 regions. Two primers from the 3' end of 18S rDNA and the 5' end of 28S rDNA sequences were chosen to amplify the specific ITS regions of Phellinus spp. Phellinus strains used in the study were divided into four dusters by the phylogenetic tree based on the amplified regions of ITS and 5.8S rDNA sequences. The first cluster consist of Phellinus hartigii IMSNU 32041 and Phellinus robustus IMSNU 32068, and the second cluster consists of Phellinus linteus strains and Phellinus weirianus IMSNU 32021. Phellinus laevigatus KCTC 6229, KCTC 6230 and Phellinus igniarius KCTC 6227, KCTC 6228 belong to the third cluster. Finally, Phellinus chrysoloma KCTC 6225 and Phellinus chrysoloma KCTC 6226 are the fourth cluster. In the second cluster the differentiation between Phellinus linteus strains and Phellinus weirianus species were not possible by the comparison of the ITS sequences. These results revealed that Phellinus linteus and Phellinus weirianus cannot be established the concept of species level only by the ITS sequences. Therefore, both physiological and molecular biological methods as well as the sequences of type strains are necessary to classify the strains of these two species accurately. The comparison of the ITS sequences of four Phellinus species indicated that the sequences of the ITS1 generally are more divergent than those of the ITS2. Although the ITS sequences are varied in some species, the conserved regions in both ITS1 and ITS2 are useful tool to differentiate the species. Phellinus linteus and related species have their specific sequences in the ITS1 compared to the other species.

Structural characteristics and chemical bonding states with temperature in barium titanate nanopowders prepared by using the solvothermal method

K.S. Hong,하명규,배종성,김주성,배유리,안창원,김일원,김종필 한국물리학회 2015 Current Applied Physics Vol.15 No.11

We report the structural characteristics and the chemical bonding states of nano-sized BaTiO3 powders before and after having been heat treatment.We prepare BaTiO3 nanopowders by using the solvothermal method at different reaction temperatures. We anneal the prepared powders at 400 and 600 ℃, respectively, for 1 h. We examine the structures of the prepared powders by using the Rietveld analysis, and the chemical bonding states of the ions by using a fitting program with an assumption that the measured spectra are Gaussian. Then, we study the morphology of the nanopowders, and measure the ferroelectric properties with frequency and reaction temperature. We show that the BaTiO3 nanopowders prepared by using the solvothermal method at lower reaction temperature exhibit the tetragonality and are useful for the electronic device applications.

영가철과 활성슬러지를 이용한 독립영양방식의 퍼클로레이트 제거 : 회분배양연구

Yeonghee Ahn(안영희),Myoung Gyu Ha(하명규) 한국생명과학회 2011 생명과학회지 Vol.21 No.3

퍼클로레이트(ClO₄<SUP>-</SUP>)는 지표수 및 토양/지하수에서 검출되는 오염물이다. 독립영양방식의 퍼클로레이트-환원세균(PRB)은 기체 수소(H₂)를 전자공여체로 사용하여 ClO₄<SUP>-</SUP>를 제거한다. 철이 부식되면 H₂를 생성할 수 있음에 착안하여 본 연구에서는 하수처리장에서 쉽게 구할 수 있는 활성슬러지를 식종하여 영가철(ZVI)을 이용한 독립 영양방식의 ClO₄<SUP>-</SUP> 제거 가능성을 조사하였다. 회분반응실험을 통해 활성슬러지미생물이 ZVI가 존재할 때 ClO₄<SUP>-</SUP>를 분해할 수 있음을 알 수 있었으며, 또한 이러한 ClO₄<SUP>-</SUP>의 생분해는 ClO₄<SUP>-</SUP>가 분해됨에 따라 생성되는 Cl<SUP>-</SUP>의 몰 농도를 통해 확인 할 수 있었다. 독립영양방식의 ClO₄<SUP>-</SUP> 제거공정에 사용된 철 입자의 표면에 간균형태의 미생물들이 존재한다는 것을 주사전자현미경을 통해 관찰하였다. 그래서 철 입자가 생물막을 형성하기 위한 담체로서도 작용할 수 있다는 것을 알 수 있었다. ZVI가 첨가된 ClO₄<SUP>-</SUP> 분해성 농화배양으로부터 채취한 생물막의 미생물군집조성은 접종균으로 사용된 활성슬러지의 그것과는 다름이 DGGE 분석 결과 나타났다. DGGE band 중에서 생물막의 주요밴드는 Clostridia 강과 가장 관련이 있는 것으로 나타났다. Perchlorate (ClO₄<SUP>-</SUP>) is a contaminant found in surface water and soil/ground water. Autotrophic perchlorate-reducing bacteria (PRB) use hydrogen gas (H₂) as an electron donor to remove perchlorate. Since iron corrosion can produce H₂, feasibility of autotrophic perchlorate-removal using zero-valent iron (ZVI) was examined in this study using activated sludge that is easily available from a wastewater treatment plant. Batch test showed that activated sludge microorganisms could successfully degrade perchlorate in the presence of ZVI. The perchlorate biodegradation was confirmed by molar yield of Cl<SUP>-</SUP> as perchlorate was degraded. Scanning electron microscope revealed that rod-shaped microorganisms on the surface of iron particles used for the autotrophic perchlorate-removal, suggesting that iron particles could serve as supporting media for the formation of biofilm as well. DGGE analyses revealed that microbial profile of the inoculum (activated sludge) was different from that of biofilm sample obtained from the ZVI-added enrichment culture used for ClO₄ <SUP>-</SUP>-degradation. A major band of the biofilm sample was most closely related to the class Clostridia.

Optical Properties and Chemical Bonding States with Annealing Conditions of ZnO Nanofibers Prepared by Using the Electrospinning Method

홍경수,Eun Sick Pak,배종성,정의덕,진종성,하명규,김종필 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.9

We have prepared ZnO nanofibers by using the electrospinning method and have analyzed the variations in their structure, optical properties, and chemical bonding states with the annealing temperature and the annealing conditions. After annealing at 500 ℃, the average diameter and the average grain size are determined to be approximately 170 nm and 50 nm, respectively. The ZnO nanofibers have a clearly visible dislocation-free crystal structure. The 2<i>p</i> level of Zn caused Zn-O bonds and the O 1<i>s</i> core level caused physisorbed O₂. When the nanofibers are annealed at 700 ℃, both ions exhibit shifts of the binding energies compared with those annealed at 500 ℃. The observed band in the visible region shows a strong temperature dependence and a red-shift with the oxygen flow in annealing process, which is related to oxygen vacancies.

Enhanced Photocatalytic Properties due to Electron-rich Ti-ion Doping in ZnFe_2O_4 under Visible Light Irradiation

Pramod H. Borse,김현규,장점석,이재성,F. Nawaz Khan,하명규,김종필,배종성,정의덕 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.4

The substitution effect of Ti^(4+) at Fe^(3+) site in ZnFe_2O_4, a spinel-phase system, has been studied and further optimized to fabricate an efficient photocatalyst. The material doped with electron donor (Ti^(+4)), ZnFe_(2−x)Ti_xO_4 with an optimum composition of x=0.06 exhibited a unchanged band gap, but generated two times higher photocurrent, and showed enhanced quantum yield (upto 0.77%) for photodecomposition of H_2O-CH_3OH mixture, than undoped material under visible light ((λ≥420 nm). In contrast, the material doped with very high concentration of Ti revealed deteriorated photochemical properties due to constituent impurity phases. The higher electron density by n-type doping seems to be responsible for the more efficient charge separation in ZnFe_(2−x)Ti_xO_4 (0.01 < x < 0.09), and hence, the high photocatalytic activity.