• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.75-80
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• 2015

Aluminum dusts, from micro to nano-scale, are widely used in various applications such as propulsion and pyrotechnic compounds because of high burning rate. In this study, the pyrolysis hazard of aluminum dusts with different median size (sized by 70 nm, 100 nm, $6{\mu}m$, $15{\mu}m$) were investigated experimentally. The thermal decomposition characteristics of aluminum dusts with the variation of heating rate were investigated using TGA (Thermo gravimetric analysis) and was estimated the minimum ignition temperature from temperature of weight gain in nano and micro-sized aluminum dusts with different diameter. In the same condition of heating rate, the temperature of weight gain in aluminum dust layers increased with increasing of particle size and increased with increasing of heating rates in air. From the results, it was estimated that the pyrolysis hazard of aluminum dusts decrease with increasing of mean diameter.

• Polymer(Korea)
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• v.25 no.5
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• pp.609-616
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• 2001

The application of microwave technology to synthesis of polymer in solvent media has been shown by the synthesis of copper phthalocyanine (CUPc). The increase of synthetic yield-was demonstrated successfully in this study. A power variable microwave synthetic system has been developed with modifying cavity of domestic microwave oven and attaching microwave power controller. The properties of the specimen synthesized at various condition under the conventional thermal processing and microwave processing has been characterized by the means of chemical analysis, X-ray diffractometry (XRD), scanning electron microscopy (SEM), and particle size analysis (PSA).

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.147-147
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• 2003

탄소/탄소 복합체의 내산화 코팅을 위하여 산화티탄, 산화알루미늄, 산화이트륨 등을 포함하는 여러 가지 인산염계 유리를 제조하였다. 유리 산화물조성 몰비는 인산에 대하여 인산알루미늄을 15몰%, 30몰%, 45몰%로 하였고 산화티탄은 70몰%, 산화 이트륨은 25몰%이 되도록 코팅 액을 제조하였다. 제조 된 코팅액은 석영 도가니에서 열처리 하여 급냉 시켰으며, 급냉 시키고 다시 130$0^{\circ}C$, 1시간 동안 열처리하여 유리를 제조하였다. 제조된 유리의 열중량, 열팽창율, 열전도도를 분석하여 탄소 복합체와의 적합성을 조사하고, 내산화성 시험을 위해 탄소/탄소 복합체에 코팅액을 도포하여 산화 감량 비율을 측정하였다. 엑스선 회절분석기와 적외선 분광기를 통하여 인산염 유리의 구조분석을 실시하고 비커스 미세 경도 시험기를 이용하여 기계적 물성을 측정하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.350-355
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• 1998

Dysprosium monotitanate $(Dy_2TiO_5)$ powder was synthesized by a simple mixed-oxide ceramics process using ethylene glycol (EG). Ethylene glycol, as the organic carrier for the metal cations, was used for polymerization mechanism. The successful used of a non-chelating polymer for the mixed-oxide ceramic process indicated that cation chelation is not the only route for creating stable ceramic precursors. Characterization of the powders by various thermal analysis, microscopy, and diffraction methods has been carried out.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.683-688
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• 1997

원전의 중대사고 발생시 형성될수 있는 노심용융물의 고화피막층을 동반하는 용융물의 자연대류 열절달 특성에 대한 실험결과를 정밀 분석하고, 이에 대한 해석적 연구를 수행하였다. 본 연구대상 실험은 종횡비가 작은 경우와 큰 경우에 대하여 용융물을 자연대류와 강제대류로서 냉각하는 조건에서 경계조건에 따른 용융물의 피막층 두께를 측정하였고, 피막층 주변의 열전달량을 측정ㆍ분석한 것이다. 실험결과를 정밀 분석한 결과, 용융물의 고화 피막층 형성이 용융물의 자연대류 열전달양에 많은 영향을 미쳤으며, 종횡비가 큰 경우는 냉각 조건도 자연대류 열전달 양에 다소 영향을 미치는 것으로 나타났다. 또한 고화층 두께 증가에 따른 종횡비 감소는 자연대류 열전달양 감소율을 작게하는 것으로 나타났다. 피막층 형성이 있는 용융물의 자연대류 열전달 해석 결과, 실험에서의 열손실 때문에 용융물의 고화 피막층 두께가 실험결과보다 다소 작게 나타났으며, 자연대류 열전달 흐름이 피막층 형성에 미치는 것으로 나타났다.

• Journal of Energy Engineering
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• v.22 no.4
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• pp.399-405
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• 2013

The gas motion inside the engine cylinder plays a very important role in determining the thermal efficiency of an internal combustion engine. A precise information of in-cylinder three dimensional complex gas motion is crucial in optimizing engine design. Homogeneous charge compression ignition (HCCI) engine is a combustion concept, which is a hybrid between Otto and Diesel engine. The turbulent diffusion leads to increased rates of momentum, heat and mass transfer. The in-cylinder turbulence flow was found to affect the present HCCI combustion mainly through its influence on the wall heat transfer. This study investigates the effect of piston geometry shape on the turbulent flow characteristics of in-cylinder from the numerical analysis using the LES model and the results obtained can offer guidelines of the combustion geometries for better combustion process and engine performance.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.1
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• pp.37-44
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• 1997

The Purpose of this study was to evaluate the effect of cooking methods and reheating on texture characteristics of sausage. Sausage samples were cooked(microwaving, gas-broiling and frying), reheated on day 3 and 6 after refrigeration and put to evaluation of sensory and texture characteristics. The results of sensory evaluation showed that hardness, salty taste, rancid flavor and after-taste were increased but wetness and chewiness were decreased by reheating after refrigeration. Overall acceptability was the highest when the samples were gas broiled and reheated on day 3 after refrigeration. As for the estimation of texture changes by rheometer, hardness, cohesiveness, elasticity, gum-miness and chewiness tended to increase by reheating after refrigeration. Hardness, cohesiveness, gumminess and chewiness were the highest when the samples were gas-broiled and reheated on day 3 after refrigeration.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.600-605
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• 1999

Methyl linoleate was oxidized at 60, 90, 120 and $150^{\circ}C$, respectively, with sparging oxygen for different periods of time. On the basis of the peroxide values determined at four temperatures, four heating times were chosen for the analysis of physicochemical parameters, such as peroxide value, total oxidation products, polymer content, viscosity, refractive index and characteristics of thermal degradation by DSC (Differential Scanning Calorimeter). The content of peroxide linkage (C-O-O-C) polymer and ether or carbon to carbon linkage (C-O-C/C-C) polymer were analyzed by High Performance Size Exclusion Chromatography (HPSEC). The polymer formed at four temperatures was qualitatively identified as dimer. The polymer with peroxide linkage (C-O-O-C) were detected from methyl linoleate oxidized at $60^{\circ}C\;and\;90^{\circ}C$, but they were not detected from methyl linoleate oxidized at $120^{\circ}C\;and\;150^{\circ}C$. The enthalpy changes increased as peroxide value increased whereas maximum degradation temperature decreased. The highest correlation coefficients were obtained between maximum degradation temperature $(T_m)$, exothermic enthalpy changes and peroxide value, peroxide linkage (C-O-O-C) polymer content.

• Korean Journal of Food Science and Technology
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• v.49 no.4
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• pp.360-368
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• 2017

The objective of this research was to elucidate the physicochemical, structural, pasting and rheological properties of potato starch isolated from a foreign potato cultivar ('Atlantic') and new domestic potato cultivars ('Goun', 'Sebong', and 'Jinsun'). Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and one-dimensional nuclear magnetic resonance (1D NMR) showed that the structural properties of potato starch did not vary significantly with cultivars. RVA analysis demonstrated that the 'Atlantic' starch had the highest breakdown viscosity among all potato starches. In steady shear rheological analysis, all potato starch dispersions showed shear-thinning behaviors (n =0.63-0.72) at $25^{\circ}C$. The highest apparent viscosity (${\eta}_{a,5}$), consistency index (K), and yield stress (${\sigma}_{oc}$) were observed in the 'Goun' starch dispersion. In dynamic shear rheological analysis, storage modulus (G') and loss modulus (G") values of new domestic potato starch dispersions were higher than those of the 'Atlantic' starch dispersion.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.84-84
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• 2018

참억새(Miscanthus sienesis)는 화본목 벼과 억새속에 속한 다년생 단자엽식물로 동아시아와 오세아니아 동쪽 해역에 자생하고 있으며, 국내에서는 관상가치가 높아 정원용이나 조경용 소재로 이용되고 있는 대표적인 산림식물이다. 억새속(Miscanthus)은 물억새(M. sachariflorus), 참억새(M. sinensis), 억새아재비(M. longiberbis), 장억새(M. changii)로 분류하고 있으며, 이는 종을 구분하는 화기구조가 작고, 변이가 다양하기 때문이다. 그 중 참억새는 이러한 변이를 이용하여 다양한 초장과 엽 무늬를 가진 재배품종이 많이 개발되었으며, 내한성 또한 강해 정원용 관상식물로서의 가치가 높이 평가되고 있다(Lewandowsik et al, 1964). 지금까지 참억새 재배품종은 엽 무늬를 중심으로 개발되어 품종간 높은 유사성을 가지고 있어 구별하는데 어려움이 있었다. 본 연구에서는 새로운 참억새 품종개발시 기존품종과의 차이를 구별할 수 있는 기준을 제시하고자 기존 참억새 재배품종들에 대해 형태적 특성을 조사 분석하여 고찰해 보았다. 조사결과 가로무늬를 가진 'Strictus'와 'Zebrinus' 품종은 형태적으로 매우 유사하였으나 전체적인 모습에서 'Zebrinus'가 'Strictus' 품종에 비해 잎의 끝부분이 늘어지는 정도가 커 처진 특성을 나타내었다. 또한, 세로무늬를 가진 'Cosmopolitan'과 'Carbaret' 품종의 경우 초장 및 엽신의 길이가 유사하였으나 엽 무늬 위치에 차이가 있는 것으로 나타났다. 엽 폭이 좁은 세엽종인 'Morning Light'와 'Little Kitten' 품종은 형태적 차이는 없지만 가장자리 엽 무늬 유무로 구분이 가능하였다. 반면에 'Adagio'와 'Little Kitten, 품종은 형태적으로 매우 유사하여 좀 더 세밀한 조사가 필요할 것으로 보인다. 앞으로 더 많은 참억새 재배품종의 형태적 특성을 조사한 자료를 이용한다면 신품종 개발시 기존 재배품종과의 차이를 비교하는데 효율적으로 이용될 것으로 기대된다.