• Journal of the Korean Ceramic Society
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• v.45 no.5
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• pp.251-255
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• 2008

Microwave dielectric properties of $MgTiO_3,\;MgWO_4,\;MgNb_2O_6$, and $MgTa_2O_6$ were investigated based on the structural characteristics. The dielectric constant (K) was dependent on the dielectric polarizabilities of the specimens, and the deviation of the observed dielectric polarizabilities (${\alpha}_{obs.}$) from the theoretical dielectric polarizabilities (${\alpha}_{theo.}$) were decreased with increasing of Mg-site bond valence. Quality factors (Qf) were affected by the sharing type of $MgO_6$ and $BO_6$ octahedra. Temperature coefficient of resonant frequency (TCF) was decreased with increasing of average octahedral distortion.

• Journal of Microbiology and Biotechnology
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• v.13 no.2
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• pp.236-242
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• 2003

A culture-independent and -dependent survey of the bacterial community structure in the rhizosphere and soil samples from hot pepper plants was conducted using 16S rDNA clone library and FAME analyses. Out of the 78 clones sequenced, 56% belonged to Proteobacteria, 4% to high G+C Gram- positive group, 3% to Cytophyga-Flexibacter-Bacreroides, and 32% could not be grouped with any known taxonomic division. Among the 127 FAME isolates identified, 66% belonged to low G+C Gram-positive bacteria (Baciilus spp.) and 26% to high G+C Gram-positive bacteria. In a cluster analysis, the results for both methods were found to be strikingly dissimilar. The current study is the first comparative study of FAME and 165 rDNA clonal analyses performed on the same set of soil, rhizosphere soil, and root samples.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.382-385
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• 2001

In the previous study, a new LTCC material in the $PbWO_{4}-TiO_{2}-B_{2}O_{3}-CuO$ system was introduced. The developed material can be sintered at $850^{\circ}C$ and its dielectric properties are $\varepsilon_{r}=20-25$, $Q{\times}f_{o}=30000\sim50000GHz$, and $\tau_{f}=0.2{\sim}30ppm/^{\circ}C$, respectively. Therefore this material can be used as a LTCC substrate material for fabrication of multilayered high frequency communication module set. In present study, using this material, tape casting condition was established. With this condition, a multilayered resonator was fabricated and its electrical properties were examined. In present study, an antenna-duplexer module was also fabricated. Frequency characteristics of as-fabricated antenna-duplexer module was compared with simulation results.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.167.1-167.1
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• 2017

전이금속 디칼코게나이드는 서로 다른 전이 금속원소와 칼코겐 원소의 결합으로 이루어진 층상 구조의 물질이다. 그 중 텅스텐 이황화물($WS_2$)은 전이금속 화합물로써 풍부한 매장량으로 인하여 가격면에서 매우 저렴하며, 높은 온도에서도 잘 견딜 수 있는 열 내구성이 강해 물 분해 반응에서 촉매로 사용될 수 있는 가능성이 제시되었다. 이러한 $WS_2$을 매장량이 적은 고비용의 백금계 촉매를 대체하기 위한 물질로서 많은 연구가 활발히 진행되고 있다. 본 연구에서는 $WO_3$ 콜로이드 용액을 전기 영동 및 황화 처리 이용하여 $WS_2$를 합성하여 수소 발생 반응(Hydrogen Evolution Reaction, HER)촉매로서의 가능성을 확인하였다.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.49-54
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• 2006

The present study conducted a numerical modeling on the diesel SCR (selective catalytic reduction) system using ammonia as a reductant over vanadium-based catalysts $(V_2O_5-WO_3/TiO_2)$. Transient modeling for ammonia adsorption/desorption on the catalyst surface was firstly carried out, and then the SCR reaction was modeled considering for it. In the current catalytic reaction model, we extended the pure chemical kinetic model based on laboratory-scale powdered-phase catalyst experiments to the chemico-physical one applicable to realistic commercial SCR reactors. To simulate multi-dimensional heat and mass transfer phenomena, the SCR reactor was modeled in two dimensional, axisymmetric domain using porous medium approach. Also, since diesel engines operate in transient mode, the present study employed an unsteady model. In addition, throughout simulations using the developed code, effects of space velocity on the DeNOx performance were investigated.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.79.2-79.2
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• 2012

In this work, vertically aligned metal oxide nanorods(ZnO, $TiO_2$, $WO_3$) were grown onto CuO film at the room temperature. The fabricated nanorods of 90nm~500nm diameter range and $1{\mu}m{\sim}15{\mu}m$ of length range. Growth of metal oxide nanorods only depends on thickness of CuO film in this method, and it is grown at both of room temperature and high temperature. That means, it is much faster mathod to make the vertical metal oxide nanorods than old method such as hydrothermal method.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.299-300
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• 2015

$TiO_2$는 내구성이 뛰어난 전기변색재료로 연구가 이루어 지고 있다. 큰 굴절율로 인해 높은 투과율을 보이는 $TiO_2$는 변색시 치밀한 구조를 가지기 때문에 전해질 양이온의 침입이 힘들어 변색효율이 $WO_3$에 비해 좋지 않다. 이를 개선하고자 작업압력을 변화시켜 기판에 입사하는 입자의 에너지를 줄임으로써 확산을 줄이고 Porous한 막을 얻고자 하였다. 작업압력이 높아짐에 따라 표면의 거칠기가 커지는 것을 확인하였고 전기변색시 효율이 커지는 것을 확인하였다.

• Journal of the Korean Chemical Society
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• v.7 no.2
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• pp.186-188
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• 1963

An attempt to improve the method of volumetric determination of tungsten developed by Luke has been made successfully. Using amalgam coated lead instead of pure metallic lead in the reduction procedure. W(VI)-W(III) reduction has been found to be quantitative in rather concentrated hydrochloric acid. Since there was no excessive dissolution of lead via reduction of hydrogen ion, lead surface was totally accessible for the reduction of tungsten and no trouble was caused by dereposition of $PbCl_2$ crystals at the nozzle of Jones reductor. Furthermore, it has been confirmed that almost 100 mg. of $WO_3$ can be handled easily if the chloride concentration of the HCl is increased by adding solid $NH_4Cl$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.04b
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• pp.53-53
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• 2002

본 연구에서는 산화텅스텐($WO_3$) 분말을 이용하여 여러 금속 기판에 텅스텐 박막을 코팅하는 방법에 관한 연구를 수행하였다. 본 연구에서 언급되는 W 코팅은 Lee 등이 보고한 W, Cu 산화물을 이용하여 W-Cu 복합분말을 제조하는 것으로부터 아이디어가 출발되었으며, 본 연구의 결과는 기존의 6불화 텅스텐 가스($WF_6$) 를 열 분해하여 증착시키는 화학증착법(CVD: chemical vapor deposition)과 순수 텅스텐 target을 sputtering하여 증착시키는 물리증착법(PVD: physical vapor deposition)과 달리, 산화텅스텐 분말, 금속 기판, 및 수소 가스만을 사용하기 때문에 경제적으로 큰 장점이 있는 새로운 코팅법의 하나로 연구되었다. 본 연구에서는 새로운 코팅법의 기구와 여러 금속에서 코팅되는 W의 코팅 현상 등에 대해 간단히 언급하고자 하였다.

• Genomics & Informatics
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• v.7 no.1
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• pp.41-45
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• 2009

The Korean Agricultural Culture Collection (KACC) has developed a web-based system to provide an integrated database with information updates about microbial resources. This integrated database consists of 5 major functions and contains general information, which includes identification numbers, culture media composition, image information, DNA sequences, patent information, and general forms for ordering and depositing microorganisms. In 2008, KACC started providing characterization information. KACC maintains 9,801 cultures of microorganisms, including 3,296 strains of bacteria, 4,734 fungi, 784 actinomycetes, 64 yeasts, and 923 others.