• 한국응용과학기술학회지
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• 제18권3호
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• pp.167-173
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• 2001

The spinel $LiMn_{2}O_{4}$ powders were synthesized at $480^{\circ}C$ for 12 h in air by a sol-gel method using manganese acetate and lithium hydroxide as starting material and the $Fe_{3}O_{4}$ powders were synthesized by the precipitation method using $0.2M-FeSO_{4}{\cdot}H_{2}O$ and 0.5M-NaOH. The synthesized $Fe_{3}O_{4}$ powders were mixed at portion of 5, 10, 15 and 20 wt% about $LiMn_{2}O_{4}$ powders through ball-milling followed by drying at room temperature for 48 h in air. The mixed catalysts were reduced at $350^{\circ}C$ for 3 h by hydrogen and the decomposition rate of carbon dioxide was measured at $350^{\circ}C$ using the reduced catalysts. As the results of $CO_{2}$ decomposition experiments, the decomposition rates of carbon dioxide were 85% in all catalysts but the initial decomposition rates of $CO_{2}$ were slightly high in the case of the $5%-Fe_{3}O_{4}$ added catalyst.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 1999년도 추계학술대회
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• pp.543-563
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• 1999

본 연구에서는 특수 설계된 연면방전(Surface discharge induced Plasma Chemical Process, SPCP) 반응기로부터 발생하는 플라스마에 의하여 일산화질소(NO)와 이산화질소($NO_2$)등 유해 환경오염 가스를 주파수, 유량, 농도, 전극재질 및 감은 횟수 등의 공정변수 변화에 따른 분해율, 소비전력 및 소비전압 등을 측정하여 최적의 공정조건과 최대의 분해효율을 얻고자 하였다. 표준시료로서 일산화질소와 이산화질소를 고전압발생기의 주파수(5~50kHz), 유해가스의 체류시간(1~10.5 초)과 초기농도(100~1000 ppm), 전극의 재질(W, Cu, Al), 전극의 굵기(1, 2, 3 mm)및 감은횟수(7회, 9회, 11회)에 대하여 플라스마 연면방전 반응기를 이용하여 분해효율을 구하였다. 유해가스(NO, $NO_2$)의 분해제거 실험결과, 10 kHz의 주파수와 각각 19.8와 20 W의 소비전력에서 각각 94.3, 84.7 %로 가장 높은 분해제거율을 나타내었고, 20 kHz이상에서는 주파수가 커질수록 분해율이 감소하였다. 또한 연면방전 반응기에서 유해가스의 체류시간이 길수록, 그리고 초기농도가 작을수록 분해율은 증가하였다. 방전전극에 대한 영향은 전극의 굵기가 굵을수록 분해율이 증가하여 본 실험의 경우 3 mm의 전극을 사용하였을 때 가장 높은 분해율을 나타내었고, 전극의 재질은 텅스텐을 사용하여 방전한 경우에 가장 높은 분해율을 보였으며 구리, 알루미늄의 순으로 낮아졌다. 방전전극의 감은 횟수에 대한 영향은 7회, 9회, 11회의 순으로 감은 횟수가 많을수록 분해율이 높아짐을 알 수 있었다.

• 한국CDE학회논문집
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• 제11권4호
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• pp.235-245
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• 2006

This paper proposes a CSG-based representation scheme for heterogeneous objects including multi-material objects and Functionally Graded Materials (FGMs). In particular, this scheme focuses on the construction of complicated heterogeneous objects guaranteeing desired material continuities at all the interfaces. In order to create various types of heterogeneous primitives, we first describe methods for specifying material composition functions such as geometry-independent, geometry-dependent functions. Constructive Material Composition (CMC) and corresponding heterogeneous Boolean Operators (e.g. material union, difference, intersection. and partition) are then proposed to illustrate how material continuities are dealt with. Finally, we describe the model hierarchy and data structure for computer representation. Even though the proposed scheme alone is sufficient for modeling all sorts of heterogeneous objects, the proposed scheme adopts a hybrid representation between CSG and decomposition. That is because hybrid representation can avoid the unnecessary growth of binary trees.

• 한국화재소방학회논문지
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• 제23권2호
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• pp.62-66
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• 2009

본 연구는 국내에서 사용되고 있는 누전차단기 외함 절연재료의 소손 특성에 대하여 연구하였다. 시료는 3개 제조사의 누전차단기 외함 절연재료를 사용하였으며, 시료의 열분해특성, 연소특성, 트래킹 특성 등을 비교 분석하였다. 열분해특성은 TGA를 사용하였으며, 연소특성은 ISO5660(Fire Tests - Reaction to Fire, part 1)을 만족하는 Mass Loss Calorimeter(FTT 사)를 사용하였고, 트래킹 특성은 고체 절연재료의 내트래킹 및 비교트래킹 지수를 측정하는 실험인 KSC IEC 60112.의 기준에 따라 분석하였다. 연구결과 A제조사의 경우 내트래킹성이 가장 우수하였고, B제조사의 경우 내트래킹성이 가장 낮은 반면 $350^{\circ}C$ 이상의 고온에서 열안정성이 가장 우수하였으며, C제조사의 경우 $400^{\circ}C$ 이하의 온도에서 열안정성이 가장 우수한 것을 알 수 있었다.

• 한국산업보건학회지
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• 제16권1호
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• pp.27-35
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• 2006

The aim of this study was to identify the sources of benzene detected in airborne of casting workplace where benzene was not used as raw material. We have identified benzene by GC/FID and GC/MSD. In this pilot test, small size iron chamber(diameter 30 cm, height 20 cm) was used. As the raw materials, new sand, recovered sand, and mixed casting sand(new sand + solidifying agent + organic resin + coating material) was tested, respectively. In the new sand benzene was not detected, but in the recovered sand and the mixed casting sand was detected. Xylenesulfonic acid(solidifying agent), one of the mixed casting sand ingredients was thought to product benzene by thermal decomposition above $400^{\circ}$..., but the other raw materials(organic resin and coating material) were thought not to product benzene. In this experiment, the most of benzene by thermal decomposition was produced within 1 hour after pouring the iron solution($1560^{\circ}$...) in small size iron chamber. When the mixed casting sand with coating material was used, the concentration of the produced benzene was average 2.91 ppm(range 1.98~3.72 ppm), and without coating material, benzene concentration was average 0.11 ppm(range 0.08~0.14 ppm).

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.40-52
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• 1998

Among the non-traditional machining methods, Abrasive waterjet machining process shows big promise in drilling difficult-to-machine materials due to its numerous advantages such as absence of heat affect zone and thermal distortion. Acoustic emission signal technique is used to understand about material removal mechanisms during abrasive waterjet drilling process. More information about the drilling process is derived through frequency decomposition of auto regressive moving average modeling representing acoustic emission signals.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2003년도 연료전지심포지움 2003논문집
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• pp.183-187
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• 2003

Carbon nanotubes, prepared by the catalytic decomposition of acetylene at $700^{\circ}C$ over a Mm based $AB_5$ hydrogen storage alloy hydride catalysts, have been used as a support for platinum electrocatalysts. The performance of this electrocatalyst In proton exchange membrane fuel cells has been studied and discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.449-452
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• 1999

NiSi were formed from either Ni monolayer or Ni/Ti bilayer and the SADS method was applied to fabricated PMOSFET with Ni-polycide gate electrodes. PMOSFET made from Ni monolayer showed thermal stability unto 300~40$0^{\circ}C$ for 600sec., and excellent C-V characteristics for long time of drive-in anneal than PMOSFET made from Ni/Ti bilayer. This was attributed to easier decomposition and subsequent Ni diffusion to SiO$_2$ layer, probably due to the presence of Ti unreducing process

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.635-641
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• 2016

Because of prohibitive data storage requirements in large-scale simulations, the memory problem is an obstacle for Monte Carlo (MC) codes in accomplishing pin-wise three-dimensional (3D) full-core calculations, particularly for whole-core depletion analyses. Various kinds of data are evaluated and quantificational total memory requirements are analyzed based on the Reactor Monte Carlo (RMC) code, showing that tally data, material data, and isotope densities in depletion are three major parts of memory storage. The domain decomposition method is investigated as a means of saving memory, by dividing spatial geometry into domains that are simulated separately by parallel processors. For the validity of particle tracking during transport simulations, particles need to be communicated between domains. In consideration of efficiency, an asynchronous particle communication algorithm is designed and implemented. Furthermore, we couple the domain decomposition method with MC burnup process, under a strategy of utilizing consistent domain partition in both transport and depletion modules. A numerical test of 3D full-core burnup calculations is carried out, indicating that the RMC code, with the domain decomposition method, is capable of pin-wise full-core burnup calculations with millions of depletion regions.

• 생태와환경
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• 제38권spc호
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• pp.31-38
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• 2005

Diel change in urea decomposition activity of epiphytic algae on Phragmites stems and phytoplankton in a shallow littoral reed zone in the south basin of Lake Biwa was investigated with an in situ technique using $^{14}C$-labelled urea. The daily rates of urea decomposition (sum of urea carbon incorporation rate and $CO_2$ liberation rate) by epiphytic and planktonic algae were calculated as 180 ${\mu}$ mole urea surface shoot area $m^{-2}\;day^{-1}$ and 210 ${\mu}$ mole urea $m^{-3}\;day^{-1}$. The chlorophyll a specific urea decomposition rates of epiphytic and planktonic algae were 4.7 to 6.4 and 4.4 to 6.2 ${\mu}$ mole urea mg chl. $a^{-1}$ incubation $time^{-1}$ in daytime and 4.2 to 5.7 and 2.4 to 3.5 ${\mu}$ mole urea mg chl. $a^{-1}\;time^{-1}$ in nighttime, respectively. High values were obtained during 12:00 ${\sim}$ 18:00 and low values during 00:00 ${\sim}$ 06:00 for both epiphytic and planktonic algal communities. A clear diel periodicity in the urea decomposing activity of the planktonic algae was observed. The activity of the epiphytic algae, on the other hand, showed no destinctive variation during a day. The present results indicate that epiphytic algae are one of the significant urea decomposers in a reed zone, and that the diel patterns are quite difference between both algal communities.