• 한국세라믹학회지
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• 제31권6호
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• pp.685-693
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• 1994

Sublimation vapour pressures and sublimation enthalpy of anhydrous bismuth trifluoride have been measured by the continuous gravimetric Cnudsen-effusion method from 639-7 to 782.8 K. Additional effusion measurements have also been made from 750.6 to 863.1 K by the torsion-effusion method. Based on a correlation of subHo298.15 and subSo298.15, a recommended P(T) equation has been obtained for BiF3(s); logP= -C/T+5.2375logT-3.205$\times$10-3+4.661$\times$104/T2+1.348 where P is in Pa, T in Kelvin, subHo298.15 in kJ mol-1 and C=( subHo298.15-13.5149)/1.9146$\times$10-2. Condensation coefficients and their temperature dependence have been derived from the effusion measurements.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1995년도 추계 학술대회논문집
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• pp.203-212
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• 1995

In this paper the upwind flux difference splitting Navier-Stokes method has been applied to study the perfect gas and the equilibrium chemically reacting hypersonic flow over an axisymmetric sphere-cone($5^{\circ}$) geometry. The effective gamma($\bar{r}$), enthalpy to internal energy ratio was used to couple chemistry with the fluid mechanics for equilibrium chemically reacting air. The test case condition was at altitude(30Km) and Mach number(15). The equilibrium shock thickness over the blunt body region was much thinner than that of perfect gas shock. The pressure difference between perfect gas and equilibrium gas was about $3\sim5$ percent. The skin friction coefficient and heat transfer coefficient were also calculated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.222-227
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• 2000

At representative thermoeconomic theory to determine the unit cost of multiple products, there are the $\ulcorner$SPECO$\lrcorner$ method of Tsatsaronis's study group and the $\ulcorner$MOPSA$\lrcorner$ method of chung-ang university phase laboratory. Against this theory, we propose new theory called $\ulcorner$Thermoeconomics to divide the exergetic cost into each working fluid$\lrcorner$ in this study. Also, we apply new thermoeconomic theory to CGAM problem (30MW-grade imaginary gas turbine cogeneration power plant) that it is representative power system in thermoeconomics theory, and we fixed to interpreted the unit cost of electricity on the part of gas turbine and the unit cost of steam exergy(enthalpy) on the part of HRSG.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 제4회 영호남학술대회 논문집
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• pp.31-36
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• 2002

In this work $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}:Co^{2+}$ single crystals were grown by the chemical transport reaction method and the structure of $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}:Co$ single crystals were monoclinic structure. The temperature dependence of optical energy gap was fitted well to Varshni equation. Also, the entropy, enthalpy and heat capacity were deduced from the temperature dependence of optical energy gap.

• 한국재료학회지
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• 제15권1호
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• pp.47-53
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• 2005

The E.M.F. of the galvanic cell with fused salt was measured to determine the activities of zinc at 720-860 K over the entire composition range of liquid Zn-In and Zn-Sn alloys. The cell used was as follows: $$(-)W{\mid}Zn(pure){\mid}Zn^{2+}(KCl-LiCl){\mid}Zn(in\;Zn-In\;or\;Zn-Sn\;alloy){\mid}W(+)$$ The activities of zinc in the alloys showed positive deviation from Raoult's law over the entire composition range. The activity of cadmium and some thermodynamic functions such as Gibbs free energy, enthalpy and entropy were derived from the results by the thermodynamic relationship. The comparison of the results and the literature data was made. The liquid Zn-In and Zn-Sn alloys are found to be close tn the regular solution. The concentration fluctuations in long wavelength limit, $S_{cc}(o)$, in the liquid alloy were calculated from the experimental results.

• 설비공학논문집
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• 제16권10호
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• pp.923-931
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• 2004

A multi-dimensional freeze drying analysis program, which took simultaneous heat and mass transfer, sublimation of ice and motion of sublimation front into full account, was developed using finite volume method with fixed grid. The effect due to the motion of sublimation interface was modeled by an enthalpy formulation streamlined for the freeze drying problems. The efficiency and accuracy of the program was validated by solving one- and two-dimensional freeze drying problems frequently encountered in industrial processes. Finally, the freeze drying processes of cylinder and slab objects with permeable side surfaces were simulated, which demonstrated the capability of the present analysis program in solving multi-dimensional freeze drying problems with complex sublimation interface configurations.

• Applied Biological Chemistry
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• 제37권6호
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• pp.463-471
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• 1994

고구마 생전분에 0.5% 농도의 계면활성제, SSL(sodium stearoyl-2-lactylate), Dimodan(mono/diglyceride), SE 1670(sucrose fatty acid ester 1670)을 첨가하여 이들 전분의 이화학적 성질과 호화 및 노화특성을 측정하였다. 고구마 전분 입자의 모양과 결정형은 계면활성제 첨가 후에도 변화되지 않았다. 계면활성제 첨가에 의해 총지방 함량이 증가하였으며 아밀로오스 함량은 감소하였고 그 정도는 SE1670>SSL>Dimodan순이었다. $80^{\circ}C$에서의 팽윤력과 용해도는 무처리 전분에 비해 계면활성제 첨가 전분은 감소하였다. 아밀로그래프에 의한 호화개시온도는 무처리 전분이 $72.5^{\circ}C$였고 계면활성제 첨가시 변화는 없었으며 Dimodan과 SE1670 첨가 전분의 경우 최고 점도가 나타났다. 시차주사열량기에 의한 호화 양상은 무처리 전분의 피크 온도와 엔탈피는 각각 $73.7^{\circ}C$, 1.3 cal/g이며, 계면활성제 첨가 전분의 호화 피크 온도는 증가하였으나 엔탈피는 감소하였다. 알칼리 호화 양상은 초기에 급격한 점도의 증가를 보이다 완만해졌으며 계면활성제 첨가 전분의 점도는 무처리 전분에 비해 감소하였으며 계면활성제 종류에 따라 차이를 보였다. ${\alpha}$-아밀라아제-요오드법에 의한 노화도는 무처리 전분에 비해 SSL과 SE1670 첨가한 전분의 노화도는 감소하였다. 시차주사열량기에 의한 노화도는 계면활성제 첨가 전분은 무처리 전분에 비해 모두 감소하였다.

• 한국응용과학기술학회지
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• 제36권2호
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• pp.407-416
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• 2019

아닐린 수용액에서의 암모늄형 양이온성 계성면활성제 (DTAB, TTAB 및 CTAB)의 미셀화에 대한 임계미셀농도(CMC)값을 UV-Vis법으로 측정하였다. 290K ~ 314K 사이에서 측정된 양이온성 계면활성제의 CMC값의 변화로부터 미셀화에 대한 Gibbs 자유에너지(${\Delta}G^0$)값을 구하고, 이 값으로부터 엔탈피(${\Delta}H^0$)와 엔트로피(${\Delta}S^0$)를 계산하고 분석하였다. 또한 n-부탄올 및 염화나트륨의 농도 변화가 미셀화에 미치는 영향을 열역학적 함수를 이용하여 비교 분석하였다. 실험한 온도 구간 및 첨가제의 농도 범위 내에서 측정된 모든 ${\Delta}G^0$ 값은 음의 값을 나타냈었으며, 엔탈피(${\Delta}H^0$) 변화값은 모두 음의 값을 그리고 엔트로피(${\Delta}S^0$) 변화값은 모두 양의 값을 나타내었다. 아닐린 수용액에서 양이온성 계면활성제의 미셀화는 자발적 발열반응이며, 열역학적 값들로부터 계산된 등구조온도에 의하면 이들 계면활성제의 미셀화는 엔탈피(${\Delta}H^0$)와 엔트로피(${\Delta}S^0$)가 거의 동일하게 기여하고 있음을 알 수 있었다.

• 한국수소및신에너지학회논문집
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• 제13권4호
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• pp.270-278
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• 2002

Mg and Mg alloys are attractive hydrogen storage materials because of their lightweight and high absorption capacity. Their range of applications could be further extended if their hydrogenation properties and degradation behavior could be improved, The main emphasis of this study was to find an economic manufacturing method for Mg-Ti-Ni-H systems, and to investigate their hydrogenation properties, In order to examine hydrogenation behavior, a Sieverts type automatic pressure-composition-isotherm(PCI) apparatus was used and the experiments were performed at 423, 473, 523, 573, 623 and 673K. The results of thermogravimetric analysis(TGA) reveal that the absorbed hydrogen contents are around 2.5 wt% for ($Mg_9Ti_1$)-10 wt% Ni. With increased Ni content, the absorbed hydrogen content decreases to 1.7 wt%, whereas the dehydriding starting temperatures are lowered by some 70-100K. The results of PCI on ($Mg_9Ti_1$)-20 wt% Ni show that its hydrogen capacity is around 5.3 wt% and its reversible capacity and plateau pressure are also excellent at 523K and 573K. In addition, the reaction enthalpy, $\Delta$HD.plateau, is $30.6{\pm}5.7kJ/molH_2$.

• 분석과학
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• 제11권2호
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• pp.92-95
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• 1998

변형된 two-bulb pyrex관을 사용하여 K-SGICs(인조흑연 층간화합물)를 합성하였다. 흑연과 칼륨을 반응시키기 위하여 two-bulb관내에 압력을 $10^{-3}$ torr로 유지하여 주었다. 변형된 방법에 의하여 얻어진 K-SGICs는 유동 파라핀 내에서 $25{\sim}1400^{\circ}C$ 사이에서 열처리하여 deintercalation을 시켰다. K-SGICs의 온도 의존성과 열적 안정성을 DSC 분석기에 의하여 특성화하였다. K-SGIC의 엔탈피와 엔트로피 형성은 여러 온도에 의존하는 열역학적 발열반응과 deintercalation을 확인하여 계산하였다. 칼륨이온의 deintercalation 반응이 얼어나는 동안 K-SGICs 의 구조변이와 열적 안정성을 XRD에 의하여 확인하였다.