• 청정기술
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• 제19권2호
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• pp.156-164
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• 2013

본 연구에서는 등온반응기와 단열반응기로 구성된 0.25 MW 메탄합성 파일롯 공정 실험을 통한 운전 특성을 분석하였다. 등온반응기는 메탄합성 반응을 통해 발생하는 열을 포화수의 유량과 압력을 통해 강제적으로 제어할 수 있는 반응기로 등온반응기와 단열반응기를 조합할 경우 기존 단열반응기만으로 구성된 메탄합성 공정에 비해 반응기 개수를 줄일 수 있다. 또한 합성가스 재순환이 불필요하기 때문에 단열반응기 조합으로 구성된 메탄합성 공정에서 비용의 약 15~20%를 차지하는 재순환 압축기를 제거할 수 있다. 등온반응기로 유입되는 합성가스의 $H_2$/CO 비가 3보다 낮은 경우에는 튜브에 충진된 촉매에 탄소 침적 현상이 일어나 반응기의 차압이 증가하였으며, $H_2$/CO 비가 3으로 공급되는 경우에는 탄소 침적 현상이 일어나지 않고 메탄합성 반응이 안정적으로 유지되어 CO 전환율 99% 이상, $CH_4$선택도 97% 이상, $CH_4$생산성 최대 $695ml/h{\cdot}-cat$를 얻을 수 있었다.

• 천문학회지
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• 제42권5호
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• pp.107-123
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• 2009

We investigate the wave properties for isothermal plasma state around to the de Sitter black hole's horizon using 3+1 split of spacetime. The corresponding Fourier analyzed perturbed perfect GRMHD equations are used to obtain the complex dispersion relations. We obtain the real values of the wave number k, from these relations, which are used to evaluate the quantities like phase and group velocities etc. These have been analyzed graphically in the neighborhood of the horizon.

• 천문학회보
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• 제37권1호
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• pp.66.2-66.2
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• 2012

Building a relativistic magnetohydrodynamic (RMHD) code based on upwind scheme is a challenging project, because eigenvalues and eigenvectors are not yet analytically given. Here, we present analytic expressions for eigenvalues and eigenvectors in isothermal flows. And then we show tests performed with a code based on the total variation diminishing (TVD) scheme.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.231-232
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• 2006

• 천문학회지
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• 제34권4호
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• pp.325-327
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• 2001

This poster summarizes numerical collapse calculations of non-rotating and rotating singular, isothermal toroids that employed the zeus2d (Norman and Stone 1992) magnetohydrodynamics package. In the non-rotating collapse calculations, it is seen that infall proceeds at a constant rate and magnetically supported, high density pseudo-disks form in the equatorial plane. With rotating clouds, however, toroidal magnetic fields grow as infall proceeds, teaming with angular momentum to slow the inflow to the center and generate outflow.

• 한국안전학회지
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• 제22권1호
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• pp.19-23
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• 2007

The aim of this study was to determine residual stresses in thermal barrier coatings(TBCs) by isothermal heating. Specimens were heated at the range of $1000{\sim}1600^{\circ}C$. A finite element method was used to determine the residual stresses. Finite element coupled heat transfer and elastic-plastic thermal stress analysis using a general purpose commercial FEM software ABAQUS. I obtained the stresses were not affected below the temperature of $1400^{\circ}C$ but affected over that of temperature.

• 한국재료학회지
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• 제14권3호
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• pp.218-223
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• 2004

P-type $\beta$-FeSi$_2$ with a nominal composition of $Fe_{0.92}Mn_{0.08}Si_2$ powders has been produced by mechanical alloying process. As-milled powders were spray dried and consolidated by atmospheric plasma thermal spraying as a rapid sintering process. As-milled powders were of metastable state and fully transformed to $\beta$-$FeSi_2$ phase by subsequent isothermal annealing. However, as-thermal sprayed $Fe_{0.92}Mn_{0.08}Si_2$ consisted of untransformed mixture of $\alpha$-$Fe_2Si_{5}$ and $\varepsilon$-FeSi phases. Isothermal annealing has been carried out to induce transformation to the thermoelectric semiconducting $\beta$-$FeSi_2$ phase. Isothermal annealing at $845^{\circ}C$ in vacuum gradually led to the thermoelectric semiconducting $\beta$-$FeSi_2$ phase transformation, but some residual metallic $\alpha$ and $\varepsilon$ phases were unavoidable even after prolonged annealing. Thermoelectric properties of $\beta$-$FeSi_2$ materials before and after isothermal annealing were evaluated. Seebeck coefficient increased and electric conductivity decreased with increasing annealing time due to the phase transition from metallic phases to semiconducting phases. Thermoelectric properties showed gradual increment, but overall properties appeared to be inferior to those of vacuum hot pressed specimens.

• Journal of Welding and Joining
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• 제35권1호
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• pp.89-94
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• 2017

The microstructure and dilatation for 0.15C steels were investigated to define the phase transformation during the quenching and partitioning (Q&P) process. For the one step Q&P dilatation, the isothermal martensite/bainite transformation occurred because the holding temperature was between $M_s$ and $M_f$. The isothermally transformed martensite/bainite and the athermally transformed martensite were produced by a loss of retained austenite. As the holding time increased, new martensite-start ($M_s$) temperature produced from the final quenching process decreased due to the carbon partitioning from the martensite to the retained austenite. This was the direct evidence of increment for the retained austenite stability. For the two step Q&P dilatation, the isothermal bainitic transformation occurred because the partitioning temperature was larger than the $M_s$ and new $M_s$. The partitioning at $400^{\circ}C$ indicated the short incubation period for the bainite transformation than the $350^{\circ}C$ partitioning because the partitioning at $400^{\circ}C$ should acquire the larger thermal driving force for carbon partitioning than the $350^{\circ}C$ partitioning. A quick drop of $M_s$ and short period of bainite incubation for the $400^{\circ}C$ partitioning steel were also the direct evidence of significant effects of carbon partitioning on the stability of retained austenite.

• 대한기계학회논문집
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• 제16권6호
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• pp.1195-1204
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• 1992

본 연구에서는 등온 평면의 온도가 0.0.deg. C부터 8.0.deg. C까지, 그리고 주위물의 온 도가 1.0.deg. C부터 10.0.deg. C까지 일 대 상향 및 하향면 주위에서 일어나는 자연대류를 유한 차분법(FDM)으로 수치해석하여 등온면 주위에서 일어나는 유동형태, 속도분포, 평균 Nusselt수를 구하여 유동 및 열전달특성을 구명하였다.

• 한국미생물·생명공학회지
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• 제44권4호
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• pp.493-496
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• 2016

Peach rosette mosaic virus (PRMV)는 1933년 복숭아에서 처음 보고되었으며, 복숭아, 자두, 블루베리, 민들레, 벚나무 등에 감염되는 식물바이러스이다. PRMV는 한국에서 보고된 적이 없으나, 식물검역에서 관리병(control viruses)으로 지정되어 있다. 이번 연구에서는 PRMV를 더욱 신속하고 특이적으로 진단하기 위하여 Loop-mediated isothermal amplification 분석법을 적용한 진단법을 개발하였다. LAMP 방법은 기존의 PCR 방법(RT-PCR 및 nested PCR)과 같은 검출 강도를 가지고 있다. 또한 LAMP 반응을 확인하기 위해 PRMV cDNA을 outer primer sets (Product size 264 bp)로 PCR 한 뒤, Pvu II (CAG/CTG) 제한효소를 처리하였다. 제한효소 처리 결과 2개의 digestion fragments (207 + 57 bp)가 확인되었다. PRMV의 LAMP 진단 방법은 관련 식물로부터 더욱 신속한 모니터링이 가능할 것으로 기대된다.