• 공업화학
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• 제17권1호
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• pp.73-81
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• 2006

가수분해시킨 폐 유리를 사용하여 발포유리블록의 제조시 발포유리블록의 안정화를 위한 열처리 공정을 조사하였으며 이를 바탕으로 상업적 생산을 위한 scale-up 실험을 시도하였다. 최적의 열처리 조건은 발포소성 후 $550{\sim}600^{\circ}C$로 급냉시켜 안정화시키고 이후 $200^{\circ}C$에서 추가적으로 열응력을 해소하고 $0.3^{\circ}C/min$의 속도로 실온까지 냉각시키는 것이다. 이러한 열처리 조건을 거침으로서 기계적으로 안정성을 지닌 $250mm{\times}250mm{\times}90mm$ 크기의 발포유리가 생산 가능하였으며 이 경우 발포유리블록의 물성은 밀도 $0.28{\pm}0.06g/cm^3$, 열전도도 $0.048{\pm}0.005kcal/hm^{\circ}C$, 흡수율 $0.5{\pm}0.09vol%$, 선팽창계수$(8.6{\pm}0.2){\times}10^{-6}m/m^{\circ}C$($400^{\circ}C$ 기준), 휨강도 $15.0{\pm}0.6kg/cm^2$, 압축강도 $39.5{\pm}0.6kg/cm^2$의 특성을 갖는 것으로 확인되었다.

• 폴리머
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• 제29권2호
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• pp.211-215
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• 2005

안정화공정은 선구물질(precursor) 섬유를 화학적, 물리적, 열적 그리고 구조적으로 안정한 탄소섬유로 전환시키는데 반드시 필요한 공정이다. 특히, $400^{\circ}C$ 이하에서 행하는 안정화공정 단계에서 발생하는 심각한 중량감소와 열수축을 동반하는 레이온섬유의 경우 그 중요성은 더욱 강조된다 레이온섬유의 안정화공정은 안정화온도뿐 아니라 승온속도, 화학전처리, 분위기가스 등 공정인자에 중요하게 의존한다. 본 연구에서는 안정화공정 승온속도 및 세 종류의 인계 난연제 처리의 유${\cdot}$무 및 농도 변화에 따라 얻어진 레이온섬유에 대하여 안정화공정 동안 열처리로 내부에서 발생하는 중량감소, 섬유직경 변화 그리고 안정화공정을 거친 레이온섬유의 열안정성을 조사하였다. 레이온섬유의 중량, 직경 및 열안정성은 승온속도 및 난연제 종류와 함량에 의존하였으며, $3\;vol\%$ 이하의 농도에서 인산으로 전처리하여 안정화공정을 수행하는 것이 레이온섬유에 대하여 후속 탄화공정을 준비하기에 가장 적절할 것으로 판단되었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.564-568
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• 1998

All elements and systems of electronics have optimum temperature conditions. A using of the thermoelectric method of cooling is the most approach for the thermal management of power electronics. An analysis of using the thermoelectric cooling and the temperature control is given as an efficient method of ensuring a work of power electronic devices in conditions of micro-miniaturization.

• 대한화학회지
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• 제29권5호
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• pp.533-538
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• 1985

Spermine에 의하여 誘發되는 凝縮 DNA 構造의 安定化에 있어서 hydrophobic interaction의 重要性을 試驗하기 위하여 spermine-DNA 複合體의 異例的 吸光度-溫度 樣相에 미치는 urea의 效果를 調査하였다. 그 結果 異例的 吸光度-溫度 樣相의 downward peak(trough) 領域에 이르는 相變移에 對한 cooperativity, enthalpy, midpoint의 값들이 Tm 領域의 값들 보다 urea에 敏感한 影響을 받았으며, urea의 濃度 增加에 따라 downward peak가 점차 사라졌다. 이 data는 異例的 吸光度-溫度 樣相을 構成하는 downward peak가 spermine에 의하여 誘發되는 hydrophobic interaction에 의한 凝縮된 tertiary structure의 形成을 나타내고 있다고 불 수 있다.

• 열처리공학회지
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• 제4권4호
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• pp.34-43
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• 1991

A small amount of misch metal and/or Zr was added as a dopant to 70.5wt----Cu-26wt----Zn-3.5wt----Al shape memory alloy in order to study the effect of grain refinement and heat treatments on the transformation behavior, stabilization of martensite, and shape memory ability. It was found that the addition of misch metal and Zr was very effective for reducing the grain size. The fracture mode has been changed from intergranular brittle fracture to ductile fracture with void formation and coalescence by the addition of misch metal and Zr. Aging of the ${\beta}$-phase decreases the $M_s$ temperature, but that of the martensite phase increases the $A_s$ temperature. The hysteresis of transformation temperature ${\Delta}T(A_s-M_s)$ has an increasing tendancy by grain refinement. The crystal structure of martensite was identified as monoclinic structure. As the grain size decreased, martensite stabilization more easily occured and the shape, memory ability has been reduced by the grain size refined.

• 한국세라믹학회지
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• 제34권10호
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• pp.1074-1082
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• 1997

Microstructure and permeability as a function of sintering temperature and composition were studied on the Ni$\delta$Cu0.4-$\delta$Zn0.6Fe2O4 ($\delta$=0, 0.1, 0.2, 0.3, 0.4) which was prepared by Cu2+ substitution for Ni2+ in Ni.0.4Zn0.6Fe2O4, then followed by 8 wt% CuO and 1wt% Bi2O3 as sintering aids. It was found that NiCuZn ferrite in which Cu2+ is substituted for Ni2+ is more effective in reduction of sintering temperature than Ni.0.4Zn0.6Fe2O4, containing CuO as a sintering aid. The specimen $\delta$=0.2 sintered at 90$0^{\circ}C$ for 2hr exhibited the highest initial permeability value ($\mu$o=280 at 1Mhz), but the real permeability decreased at the frequency under 10 MHz. EPMA analysis showed that Ni$\delta$Cu0.4-$\delta$Zn0.6Fe2O4 ($\delta$=0.4), sintered at 95$0^{\circ}C$ for 2hrs consisted of three phase regions of Ni.0.3Cu0.1Zn0.6Fe2O4 region, Cu and Bi liquid existed at the 3-point boundary, although the stabilization energy of Ni2+ is higher than that of Cu2+ in B site.

• Carbon letters
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• 제21권
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• pp.51-60
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• 2017

Isotropic pitch-based fibers produced from coal tar pitch with the melt-blowing method were carbonized at temperatures ranging from 800 to $1600^{\circ}C$ to investigate their crystalline structure and physical properties as a function of the carbonization temperature. The in-plane crystallite size ($L_a$) of the carbonized pitch fiber from X-ray diffraction increased monotonously by increasing the carbonization temperature resulting in a gradual increase in the electrical conductivity from 169 to 3800 S/cm. However, the variation in the $d_{002}$ spacing and stacking height of the crystallite ($L_c$) showed that the structural order perpendicular to the graphene planes got worse in carbonization temperatures from 800 to $1200^{\circ}C$ probably due to randomization through the process of gas evolution; however, structural ordering eventually occurred at around $1400^{\circ}C$. For the carbonized pitch powder without stabilization, structural ordering perpendicular to the graphene planes occurred at around $800-900^{\circ}C$ indicating that oxygen was inserted during the stabilization process. Additionally, the shear stress that occurred during the melt-blowing process might interfere with the crystallization of the CPF.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.351-354
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• 2002

The new enhanced method of temperature control need not any reference temperature, the system itself can find the melting temperature of gallium as a reference point by dithering input heat flux. If gallium is in melting state, the latent heat of fusion works, so gallium temperature does not change on dithering input heat flux. Also, the control method can determine the state of gallium; solid, liquid, or melting state by investigating the temperature in gallium. We apply this new temperature stabilization method to stabilize a Fabry-Perot cavity, which serves as a ultimate length measurement technique. We achieved 1 mK-temperature stability and 1.5426 nm/ 95 mm-length stability over 10 hours.

• 반도체디스플레이기술학회지
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• 제9권4호
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• pp.71-76
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• 2010

According to recent changes in industry for semiconductor devices, a low-temperature treatment has become a necessity. These changes relate to size refinement and the development of new materials. While variation in cooling efficiency does not affect the yield when using a high-temperature treatment, uniform cooling efficiency is necessary avoid "inconsistencies/bends" in low temperature treatments. However it is difficult to increase temperature stabilization in low temperature treatments. In this paper, using CFD (Computer Fluid Dynamics), we analyze and manipulate the design and input of the low-temperature system to attempt to control for temperature variations within the quartz tube, of which airflow appears to be a predominant factor. This simulation includes variable inputs such as airflow rate, head pressure, and design manipulations in the S.C.U. (Super Cooling Unit).

• 청정기술
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• 제19권4호
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• pp.469-475
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• 2013

본 연구에서는 팜 잔사유를 이용하여 고품위화된 저등급 석탄의 건조 안정화 특성을 알아보았다. 인도네시아 저등급 석탄인 에코탄을 사용하였고, 팜지방산증류물(palm fatty acid distillate, PFAD)을 혼합시킨 후 $107^{\circ}C$ 질소분위기에서 건조하였으며 그 후에 안정화 특성을 평가하였다. 교차점온도(crossing-point temperature, CPT) 측정을 통해 자연발화 경향을 확인하였으며, 저온산화 실험을 통해 $CO_2$, CO 가스 배출량은 건조석탄보다 고품위 석탄이 감소하는 것을 확인하였다. 수분 재흡착 실험을 통해 고품위 석탄이 대기방치와 항온항습 분위기에서 수분 재흡착이 줄어드는 것을 확인하였다. 고품위화된 석탄은 PFAD의 표면코팅을 통해 안정화 되며, 함량이 증가할수록 안정화도가 높아졌다.