• 대한환경공학회지
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• 제27권7호
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• pp.697-703
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• 2005

본 연구에서는 주문진사 입경, 일차 및 이차 코팅온도, 코팅시간, 및 초기 3가철 주입농도를 변화시키면서 철을 코팅시킨 모래흡착제(Iron-Coated Sand, ICS)를 제조하였다. ICS 제조의 최적조건은 코팅효율, 코팅된 철의 안정성, 및 비소제거능 으로부터 선정하였다. 철코팅 효율은 입경이 작은 모래를 지지체로 사용하고 일차코팅온도를 높여주었을 때 뚜렷이 향상되었다. 철의 코팅효율은 이차코팅온도 및 코팅시간에는 크게 영향을 받지 않았지만 As(V) 흡착능은 이차코팅온도가 증가됨에 따라 크게 감소하는 것으로 나타났다. 이러한 결과들을 고려하여 ICS의 최적 이차코팅 조건을 $150^{\circ}C$ 온도조건과 1시간의 가열시간으로 선정하였다. Fe(III) 주입농도 변화에 따른 철 코팅효율은 0.8 Fe(III) mol/kg sand 될 때 까지는 뚜렷이 증가하였지만 그 이상에서는 큰 차이가 없었다. 기리고 Fe(III) 주입농도를 증가시킬수록 As(V) 흡착능도 증가하였으며 0.8 Fe(III) mol/kg sand 조건에서 최대값을 보여주었다. 이차 코팅온도 및 시간은 ICS 안정성의 주요변수로서 코팅온도를 높이고 코팅시간을 길게 할수록 ICS로 부터 용출되는 철의 양은 감소하였다. ICS에 대한 As(V)의 흡착은 낮은 pH에서 흡착량이 증가하는 전형적인 음이온형 흡착경향을 보여서 ICS는 강한 산성을 띄는 오염수내에 함유된 As(V)를 제거하는데 적용이 가능함을 알 수 있었다.

• 한국주조공학회지
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• 제13권4호
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• pp.323-332
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• 1993

An implicit finite difference formulation with three methods of latent heat treatment, such as equivalent specific heat method, temperature recovery method and enthalpy method, was applied to solidification analysis. The Neumann problem was solved to compare the numerical results with the exact solution. The implicit solutions with the equivalent specific heat method and the temperature recovery method were comparatively consistent with the Neumann exact solution for smaller time steps, but its error increased with increasing time step, especially in predicting the solidification beginning time. Although the computing time to solve energy equation using temperature recovery method was shorter than using enthalpy method, the method of releasing latent heat is not realistic and causes error. The implicit formulation of phase change problem requires enthalpy method to treat the release of latent heat reasonably. We have modified the enthalpy formulation in such a way that the enthalpy gradient term is not needed, and as a result of this modification, the computation stability and the computing time were improved.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.332-336
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• 2007

Temperature is an essential process variable in nanoimprint lithography(NIL) where the temperature varies between room temperature and above the glass transition temperature. To simulate NIL process, we employ both the Nose-Poincare method for temperature controlled molecular dynamics(MD) and force field for polymer material i.e. polymethyl methacrylate(PMMA), which is most widely selected as NIL resist. Nose-Poincare method, which convinces the conservation of Hamiltonian structure and time-reversal symmetry, overcomes the drawbacks inherent in the conventional methods such as Nose thermostat and Nose-Hoover thermostat. Thus, this method exhibits enhanced numerical stability even when the temperature fluctuation is large. To describe PMMA, we adopt the force field which account for bond stretch, bending, torsion, inversion, partial charge, and van der Waals energy.

• Journal of the Korean Wood Science and Technology
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• 제43권4호
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• pp.470-477
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• 2015

국내산 잣나무(Pinus koraiensis Sieb. et Zucc.) 열압밀화재의 치수안정성 확보를 위해 열압밀화 후 열처리를 실시하여 흡수시험을 실시하였다. 잣나무재를 압축세트량 50%로 열압밀화하여 비중 0.84의 고비중재를 얻을 수 있었다. 열처리 온도와 시간이 증가함에 따라 열압밀화재의 흡수성과 팽윤성은 감소하였다. 그리고 열압밀화 후 열처리에 의해 열압밀화재의 치수안정성은 크게 향상되었다. 대조군의 두께 회복률이 11.5%인 반면, $120^{\circ}C$ 온도에서 24시간 열처리 된 그룹의 두께회복도는 3.8%로 나타났다. 열압밀화 후 열처리는 열압밀화재의 치수안정성 확보를 위한 매우 효과적인 방안임을 확인하였다.

• 한국식품과학회지
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• 제27권4호
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• pp.571-575
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• 1995

피부조직 콜라겐의 열안정성에 대한 기초자료를 얻고자 DSC를 이용하여 Tm(transition temperature)와 ${\Delta}H(enthalpy)$를 측정하였다. 수화시간과 수화율에 따른 불용성 콜라겐의 DSC 특성은 수화시간에 비하여 수화율이 콜라겐 구조안정성에 미치는 영향이 큰 것으로 나타났으며, 수화율이 증가할수록 Tm은 낮아지고 ${\Delta}H$는 증가하였다. 주령 및 성별에 따른 acetone dried skin의 Tm 및 ΔH는 암컷의 경우보다 수컷의 경우가 다소 높았으며, 주령이 증가할수록 Tm과 ${\Delta}H$가 서서히 증가하고 있어 열안정성은 나이와 관계가 있음을 보여주었다. Acetone dried skin의 경우와는 달리 염가용성 콜라겐의 DSC 특성값은 암컷의 경우가 수컷의 경우보다 다소 높았으며, 암컷의 Tm과 ${\Delta}H$는 주령의 증가에 따라 유의적으로 감소하는 경향을 보였다. 이러한 결과는 피부조직내에서의 콜라겐 구조는 성별 또는 주령에 따라 달리 변화되고 있음을 간접적으로 시사한 것으로 생각되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.301-301
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• 2008

Ion beam (IB)-induced alignment of inorganic materials has been investigated intensively as it provides controllability in a nonstop process for producing high-resolution displays[1][2]. LC orientation via ion-beam (IB) irradiation on the nitrogen doped diamond like carbon (NDLC) thin film deposited by physical deposition method-sputtering was embodied. The NDLC thin film that was deposited by sputter showed uniform LC alignment at the 1200eV of the ion beam intensity. The pretilt angle of LC on NDLC thin films was measured with various IB exposure time and angle. The maximum pretilt angle were showed with IB irradiation angle of $45^{\circ}$ and exposure time of 62.5 sec, respectively. To show NDLC thin film stability in high temperature, thermal stability test was proceeded. The uppermost of the thermal stability of NDLC thin film was $200^{\circ}C$. In this investigation, the electro-optical (EO) characteristics of LC on NDLC thin film were measured.

• 한국표면공학회지
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• 제43권2호
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• pp.57-63
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• 2010

In this study, thermal stability of the mechanical properties of Ni-P-B and Ni-P-Fe layers electroplated on Alloy 600 material was evaluated by measuring their microhardness, tensile strength, and elongation after heat treatment at $325^{\circ}C$ and $400^{\circ}C$. According to the results, there was no noticeable change in microhardness of the two electrodeposits before and after heat treatment at the temperatures for 30 days. In the case of a Ni-P-B electrodeposit, ultimate tensile strength (UTS) slightly increases with heat treatment time, while its elongation decreases, showing good thermal stability in the mechanical properties at high temperature. On the other hand, UTS and elongation of Ni-P-Fe decrease with heat treatment time, which is very unusual observation. This result was attributed to the bad microstructure of Ni-P-Fe having many defects in the deposit formed early stage of an electroplating process and their redistribution to link to become large ones during heat treatment.

• Journal of Microbiology and Biotechnology
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• 제31권3호
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• pp.419-428
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• 2021

To efficiently recycle GH78 thermostable rhamnosidase (TpeRha) and easily separate it from the reaction mixture and furtherly improve the enzyme properties, the magnetic particle Fe3O4-SiO2-NH2-Cellu-ZIF8 (FSNcZ8) was prepared by modifying Fe3O4-NH2 with tetraethyl silicate (TEOS), microcrystalline cellulose and zinc nitrate hexahydrate. FSNcZ8 displayed better magnetic stability and higher-temperature stability than unmodified Fe3O4-NH2 (FN), and it was used to adsorb and immobilize TpeRha from Thermotoga petrophilea 13995. As for properties, FSNcZ8-TpeRha showed optimal reaction temperature and pH of 90℃ and 5.0, while its highest activity approached 714 U/g. In addition, FSNcZ8-TpeRha had better higher-temperature stability than FN. After incubation at 80℃ for 3 h, the residual enzyme activities of FSNcZ8-TpeRha, FN-TpeRha and free enzyme were 93.5%, 63.32%, and 62.77%, respectively. The organic solvent tolerance and the monosaccharides tolerance of FSNcZ8-TpeRha, compared with free TpeRha, were greatly improved. Using naringin (1 mmol/l) as the substrate, the optimal conversion conditions were as follows: FSNcZ8-TpeRha concentration was 6 U/ml; induction temperature was 80℃; the pH was 5.5; induction time was 30 min, and the yield of products was the same as free enzyme. After repeating the reaction 10 times, the conversion of naringin remained above 80%, showing great improvement of the catalytic efficiency and repeated utilization of the immobilized α-L-rhamnosidase.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.21-24
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• 2003

The understanding of the mechanism of device degradation has been accomplished recently, for devices using $AlQ_3$ electron transport and emitter molecule. In this presentation the experimental evidence for the degradation mechanism of $AlQ_3$ based devices will be reviewed, showing that the hypothesis of an unstable $AlQ_3^+$ cation explains a large amount of experimental data. This hypothesis, however, explains not only the room temperature device degradation in time but also sheds light on temperature stability of OLEDs. Dependence of half-life of a series of devices with an emitter layer composed of a mixture of $AlQ_3$ and different hole transport molecules (mixed emitter layer) will be discussed when they are operated at elevated temperatures. These results can also be explained in the framework of an unstable $AlQ_3^+$ species. An OLED structure containing a doped mixed emitter layer will be described, which shows extraordinary stability, half-life of 1200 hours at operating temperature of 70 C and initial luminance of 1650 $cd/m^2$. We will also discuss a novel Black $Cathode^{TM}$ OLED with reduced optical reflectivity, which is also stable at elevated temperatures. The new cathode utilizes a conductive light-absorbing layer made of a mixture of metals and organic materials.

• 대한전자공학회논문지
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• 제25권11호
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• pp.1335-1341
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• 1988

A pH-ISEFET microprobe for in vivo measurements has been fabricated by combining ISFET (SL-IIS) chip and capillary thin film reference electrode. A two-step TCE oxidation for the gate oxide layer and multilayer encapsulation using silicone rubber and epoxy were specially used for the improvement of the stability and temperature dependence of the ISFET's. The measured sensitivit, response time and temperature dependence of the pH-ISFET microprobes are 50 mV/pH, less than one second, and - 0.01 pH/$^{\circ}$ , respectively. By operating continuously more than 40 days, a long term stability of 0.016 pH/day is obtained. The result of pH monitoring of femoral arterial blood in a rabbit is fairly good agreement with the value of blood gas analysis.