Ohmic heating uses electric resistance heat which occurs equally and rapidly inside of food when electrical current is flown into. In other study, we researched about soybean protein’s characteristic changes by ohmic heating. Nevertheless treated same temperature, denaturation of soybean protein were accelerated by ohmic heating than conventional heating. In this time, we studied thermal property change of potato starch by ohmic heating besides conventional heating. For this purpose, potato starch was heated at same subgelatinization temperature by ohmic and conventional heating. And thermal properties were tested using DSC. Annealing of starch is heat treatment method that heated at 3～4% below the gelatinization point. DSC analysis results of this study, the T_o, T_p, T_c of potato starch levels were increased, whereas T_c～T_o was narrowed. This thermal property changes appear similar to annealing’s result. It is thought the results shown in this study, because the heating from below the gelatinization point. 6, 12, 24, 72, and 120 hours heating at 55℃ for potato starch, T_o, T_p, T_c values continue to increased with heating time increase. The gelatinization temperature of raw potato starch was 65.9℃ and the treated starch by conventional heating at 55℃ for 120 hr was 72℃, ohmic was 76℃. The gelatinization range of conventional (72 hr) was 10℃, ohmic was 8℃. In case of 24 hours heating at 45, 50, 55, 60, 65℃ for potato starch, the result was similar to before. T_o, T_p, T_c values continue to increased and gelatinization range narrowed with heating temperature increase. In case of conventional heating at 60℃, the results of gelatinization temperature and range were 70.1℃ and 9.1℃. And ohmic were 74.4℃ and 7.5℃. When viewed through the results of the above, the internal structure of starch heated by ohmic heating was found that the shift to a more stable form and to increase the homology of the starch internal structure.

폐 PVC전선의 열적분해 특성에 관한 연구를 TGA 및 고정층 반응기를 이용하여 연구하였다. 본 연구에서는 분해온도, 공기유량 및 CaO/ PVC의 비를 실험조건으로 고려하였으며, PVC전선의 열적분해과정에서 발생되는 염화수소 및 독성가스의 제거를 위한 CaO의 첨가에 대한 효과를 검증하기 위하여 PVC 전선의 열적분해 과정에서 생성되는 기상 생성물을 GC/MS를 이용하여 분석하였다. 또한 CaO의 첨가효과를 고찰하고자 액성 생성물에 대한 GC/MS을 함께 수행하였으며, 분해온도, 공기유량 및 CaO/PVC의 비에 따른 액상, 기상 및 고상 잔류물의 수율 변화를 함께 고찰하였다. 본 연구로부터 CaO의 첨가량이 증가할수록 PVC의 열적분해 과정에서 발생되는 염화수소의 제거량이 증가함을 확인하였다.

Experimental analysis has been carried out to investigate thermal characteristics of hydraulic system in special vehicles. Hydraulic system performance is largely influenced by oil temperature, and there are considerable performance decline and malfunctions in the system for high temperature conditions caused by heavy load and continuous operation. Transient oil temperature and pressure variation are analyzed and heat generation rates in the several main system parts are compared for various flow rates. With the start of system operation oil temperature gradually increases, and viscosity deceases by about 70% as temperature increases from 20℃ to 80℃. Operation pressure in the hydraulic system decreases with oil temperature, and its variation rate becomes less steep as oil temperature increases. Heat generation rate in hydraulic pump also depends on the oil temperature, and it reaches maximum near 50℃. These results in this study can be applied to optimal design of efficient hydraulic system in special vehicles.

Poly propylene carbonate (PPC)와 cloisite 20B (PPC/C-20B)을 solution method를 통하여 합성하였고, 이를 통해 합성된 나노 조성물의 morphology, 열적 특성, 수분 흡수의 특성을 평가하였다. 나노 조성물의 구조는 X-ray diffraction (XRD) 로 확인하였고, 열적 특성은 thermal gravimetric analysis (TGA)와 differential scanning calorimetric (DSC)를 이용해 분석하였다. TGA와 DSC의 결과를 통해 나노 조성물은 기존의 PPC에 비해 높은 열적 안정성을 가짐을 확인할 수 있었다. DSC측정에서 5 wt%의 clay를 포함한 nanohybrid의 유리전이온도는 순수한 PPC의 21℃에서 30℃로 9℃ 증가하였고, TGA 측정을 통해 확인한 열분해온도(Td50%)는 순수 PPC에 비해 23℃가 높아졌음을 확인하였다. 또한 PPC 나노 조성물의 수분 흡수량은 기존의 PPC에 비해 상당히 감소하였다. 이는 clay의 PPC matrix 구조 내에 존재함으로 인해 수분 흡수를 감소시킨 것으로 해석할 수 있다. 수분 흡수는 코팅 막의 분해를 유발하고 물리적, 기계적 성능에 영향을 미친다. 따라서 나노 조성물로 인한 PPC의 열적 안정성, 수분흡수도 향상은 PPC의 사용과 실제 공정에 중요한 변수로 작용할 수 있다.

The amorphization process and the thermal properties of amorphous TiCuNiAl powder during milling by mechanical alloying were examined by X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The chemical composition of the samples was examined by an energy dispersive X-ray spectrometry (EDX) facility attached to the scanning electron microscope (SEM). The as-milled powders showed a broad peak (2 = 42.4) with crystalline size of about 5.0 nm in the XRD patterns. The entire milling process could be divided into three different stages: agglomeration (0 < t 3 h), disintegration (3 h < t 20 h), and homogenization (20 h < t 40 h) (t: milling time). In the DSC experiment, the peak temperature T and crystallization temperature T were 466.9 and 444.3, respectively, and the values of T, and T increased with a heating rate (HR). The activation energies of crystallization for the as-milled powder was 291.5 kJ/mol for T.

The combustion reaction of polyvinylchloride(PVC) was investigated using a thermogravimetric technique under an air atmosphere condition at several heating rates from 10 to 50℃/min. To obtain information on the kinetic parameters, the dynamic thermogravimetric analysis curve and its derivative were analyzed by a variety of analytical methods such as Kissinger, Friedman, Chatterjee-Conrad, Ozawa and Coats-Redfern methods. The combustion reaction of PVC proceeded in two steps; the first step was caused by the dehydrochlorination process in PVC, and the second step by the combustion of polyene. The comparative works for the kinetic results obtained from various methods should be performed to determine the kinetic parameters, because there are tremendous differences in the calculated kinetic parameters depending upon the mathematical method taken in the analysis.

The combustion reaction of polypropylene was investigated using a thermogravimetric technique under an air atmosphere condition at several heating rates from 10 to 50℃/min. To obtain information on the kinetic parameters, the dynamic thermogravimetric analysis curve and its derivative were analyzed by a variety of analytical methods such as Kissinger, Friedman, Freeman-Carroll, Chatterjee-Conrad, Ozawa and Coats-Redfern methods. The comparative works for the kinetic results obtained from various methods should be performed to determine the kinetic parameters, because there are tremendous differences in the calculated kinetic parameters depending upon the mathematical method taken in the analysis.

Both photoluminescence and thermal characteristics for SrAl2O4:Eu+2,Dy+3 phosphors synthesizedwith various aluminum compounds (α-Al2O3, γ-Al2O3, amorphous-Al2O3 and Al(OH)3) were investigated in thisstudy. The formation temperature of the host SrAl2O4 crystal is changed by these various aluminumcompounds, as a result of the different thermal decomposition temperature of SrCO3 phase. Among thesecompounds, the amorphous-Al2O3 phase shows the lowest formation temperature of the host SrAl2O4 crystal.The PL emission and excitation spectra of SrAl2O4:Eu+2, Dy+3 phosphor are not affected by these aluminumcompounds. After the removal of the Xenon lamp excitation (360nm), however, the excellent long-phosphorescent property of the phosphor is obtained by the amorphous-Al2O3 phase, although the decay timefor all phosphors decrease exponentially.

Silica hydrogel was synthesized by the reaction of liquid sodium silicate with sulfuric acid. The condensation polymerization of the synthesized hydrogel was carried out via an aging process under the acidic or alkaline conditions. Nano porous silica with the pore size below 3 nm and surface area of , was obtained by the above processes in acidic ranges(pH : 3~5). The pore size and surface area of the silica varied with pH, and in alkaline ranges(pH : 8~10), those were 21 nm and respectively. The characteristics of the silica varied with the thermal treatment which caused the change of surface area, pore volume and pore diameter.

N2처리에 의해 Si (001) 기판에 형성된 C49상의 구조를 갖는 에피택셜 TiSi2상의 열적 거동과 결정학적 특성을 X선 회절법 (XRD)과 고분해능 투과전자현미경법 (HRTEM)으로 조사하였다. 에피택결 C49-TiSi2상은 1000˚C 정도의 고온에서도 안정상인 C54상으로 상변태하지 않고 형태적으로도 고온 특성이 우수하다는 것이 밝혀졌다. HRTEM 결과로부터 에피택결 TiSi2상과 Si 사이의 결정학적 방위관계는 (060) [001]TiSi2//(002) [110]Si임을 알 수 있었고 계면에서의 격자 변형에너지는 misfit 전위의 형성에 의하여 해소되는 것을 확인할 수 있었다. 또한 HRTEM상의 해석과 원자 모델링을 통하여 Si에서 에피택셜 C49-TiSi2상의 형성기구와 C49상의 (020) 면에 존재하는 적층결함을 고찰하였다.

자동차, 항공기 및 기타 산업에서 복합재료의 사용은 증가되어 왔고 활발한 연구가 진행되고 있다. 이러한 복합재료중의 하나인 carbon-epoxy 복합재료의 열 특성에 관하여 알아보았다. 반복적인 냉각과 가열이 부가된 후 복합재료의 탄성계수의 변화를 관찰하여 봄으로써 복합재료가 가지고 있는 여러 열 특성에 관하여 여러 열 특성에 관하여 연구하였다. 이 연구에서는 G(sub)13값은 약한 감소하기는 하였으나 별다른 변화를 보이지 않았으며 열충격의 경우가 열피로의 경우보다 변화량이 작았다. E1값은 가해진 온도와 가열 횟수에 따라하여 조금씩 증가하였고, E2, G(sub)23값은 열피로의 경우 처음에는 어느 정도 그 값이 감소하나 가해진 횟수에는 큰 영향을 받지 않았으며 열충격의 경우에는 온도에 따라 다른 현상을 보였다.