• Korean Journal of Food Science and Technology
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• v.22 no.7
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• pp.833-839
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• 1990

To examine the effects of nitrogen flushing on the storage stability of red pepper powders, the color and capsanthin and capsaicin contents were investigated. Capsanthin and capsaicin contents of red pepper powders during their storage decreased as the increase of temperature. Nitrogen flushing packaging was good for the retention of capsanthin and capsaicin than air packaging. Brown color of red pepper powders during their storage differed with storage temperature and packaging condition, thus low temperature and nitrogen reduced the brown color substantially, L and b values by Hunter's color were almost not changed during 10 months storage of red pepper powders, and a value was decreased as the increase of temperature. Therefore, nitrogen flushing packaging for the storage of red pepper powders was good than air packaging.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.58-64
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• 2007

Propellant pressurization system in liquid rocket propulsion system plays a role supplying pressurant gas at a controlled pressure into the ullage space of propellant tanks. The most important design parameter for such propellant pressurization system is the temperature of pressurant gas fed from pressurant tank, which is placed inside of cryogenic propellant tank. Such pressurant is gaseous state, of which density is very sensitive to the temperature of pressurant. Previous investigation dealt with thermal correlation of pressurant and external fluid at room temperature. This study investigates the temperature variation of cryogenic pressurant (GHe) at the time when the pressurant is coming out of pressurant tank, which is submerged in a liquid oxygen, experimentally as well as numerically.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1121-1126
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• 2010

This study is to investigate the effects of aromatics and T90 for low cetane number (CN) fuels on combustion and exhaust emissions in low-temperature diesel combustion. We use a 1.9-L common rail direct injection diesel engine at 1500 rpm and 2.6 bar BMEP. Low temperature diesel combustion was achieved via a high external EGR rate and strategic injection control. The tested fuels four sets: the aromatic content was 20% (A20) or 45% (A45) and the T90 temperature was $270^{\circ}C$ (T270) or $340^{\circ}C$ (T340) with CN 30. Given the engine operating conditions, the T90 was the stronger factor on the ignition delay time, resulting in a longer ignition delay time for higher T90 fuels. All the fuels produced nearly zero PM because of the extension of the ignition delay time induced by the low cetane number. The aromatic content was the main factor that affected the NOx and the NOx increased with the aromatic content.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.566-573
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• 1994

The diamond synthesis by combustion flame method is considerably affected by the substrate surface temperature and its distribution which are mainly controlled by the ratio of mixed gas, $O_2/C_2H_2$. In order to elucidate the role of gas ratio in the diamond synthetic process by combustion flame, under various gas ratios (R=0.87~0.98; R=ratio of flow-rate of $O_2/C_2H_2$ gas) the substrate temperature was measured by using thermal video system and the morphological change of diamond crystals was analysed by using SEM, Raman spectroscope, and X-ray diffraction method. With increasing the gas ratio, i.e., decreasing the hydrocarbon content, the nucleation rate of diamond crystal was lowerd. It was also found that the morphology of diamond crystals changed from the cubo-octahedron type consisting of (100), (111) plane to the octahedron type of (111) plane. The increase of the substrate temperature consistently resulted in the increase of the nucleation rate as well as the growth rate of diamond crystals in which the surface of diamond crystal dominantly consisting of (100) plane.

• Clean Technology
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• v.9 no.4
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• pp.169-177
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• 2003

In order to develope a clean technology by liquid-supported membrane of ionic liquid/PVDF, the solubility of R22 and HFP gases using BMIBF4 as ionic liquid were measured at temperatures from 0 to $30^{\circ}C$, at total pressures up to 4 bars. The solubility of R22 in this ionic liquid was shown a rapid increasing tendency with increases of pressure and decreases of temperature, respectively, whereas the solubility of HFP was showed only a little in the same conditions. Based on these results, liquid-supported membranes of ionic liquid/PVDF were prepared by variables of the deposition amount of ionic liquid in polymer matrix, PVDF and were applied to the separation of fluoro-gases(R22, HFP) including $N_2$ gas. The permeability of R22 was rapidly increased by depending on the deposition amounts of ionic liquid, whereas both of HFP and $N_2$ were just showed so little. Especially, the diffusivity coefficient and solubility parameter of R22 were increased by lower operating temperatures and increased deposition amount of ionic liquid in 1iquid membrane. In conclusion, the selectivity of R22 against HFP was changed to 10-45 times depending on both of operating temperatures and the deposition amount of ionic liquid in BMIBF4/PVDF liquid membrane.

• Korean journal of food and cookery science
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• v.14 no.2
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• pp.182-187
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• 1998

The changes in weight, reducing sugar content, sugar composition and enzyme activities (${\beta}$-amylase and invertase) of sweet potato were studied with three kinds of cooking methods, microwave oven, gas oven, and steaming. The weights of sweet potato cooked by microwave oven and gas oven were decreased with increasing cooking time, whereas that of steaming was increased with cooking time. Reducing sugar content of sweet potato cooked by microwave oven was increased till 40 seconds, but decreased thereafter. In the cooking methods using gas oven and steaming, reducing sugar content were increased with cooking time. And reducing sugar content were 334.60 mg/g and 381.29 mg/g, respectively at 100$^{\circ}C$ of cold point in sweet potato cooked by gas oven and steaming. Raw sweet potato consisted of fructose (1.56 mg/g), glucose (1.79 mg/g), sucrose (5.58 mg/g), and maltose (2.22 mg/g). The contents of fructose, glucose, and sucrose were decreased during cooking process. But maltose content was increased with cooking time. Especially, maltose contents were 24.81 mg/g and 28.10 mg/g at 100$^{\circ}C$ of cold point in sweet potato cooked by gas oven and steaming. The activities of ${\beta}$-amylase and invertase were decreased with cooking time. Microwave oven-cooked sweet potato did not show on invertase activity.

• Bulletin of Korea Environmental Preservation Association
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• v.8 no.17
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• pp.32-33
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• 1986

• 기계와재료
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• v.22 no.3
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• pp.96-109
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• 2010

자동차는 다양한 형상과 기능을 가진 부품소재의 집합체라 할 수 있다. 자동차의 고출력화에 의한 연비향상과 각국의 환경규제 강화 요건을 충족시키기 위해 자동차 엔진의 작동온도와 이에 따른 배기가스의 온도가 꾸준히 높아지는 추세이다. 따라서 고온재료의 선택과 사용이 보다 중요해 지고 있다. 자동차에 사용되는 고온 부품은 설계사양에 맞추어 그리고 경제적인 측면을 고려하여 내열재료를 사용하는 방법과 표면처리를 하는 두 가지 방법이 주로 채택되고 있다. 내열재료를 사용하는 대표적인 부품은 엔진을 구성하는 부품과 연소실로부터 나오는 고온 고압의 배기가스가 이동하는 배기계 부품이다. 엔진을 구성하는 부품 중에는 냉각수에 의해 온도가 제어되는 부분은 경제적인 소재가 사용되나 밸브와 같은 부품은 고온재료가 채용된다. 가장 높은 온도에서 사용되는 배기계 부품에는 경제성이 감안되면서도 높은 열적, 기계적 안정성이 동시에 요구되고 있다. 전통적으로 배기부품에는 구상흑연주철이 널리 사용되어 왔고 현재에도 원가 측면의 강점을 이용해 대부분의 차량에 적용되고 있으나 일부 고출력, 고배기량 엔진의 경우에는 주철의 한계온도 이상의 배기온도가 요구되어 스테인리스 강을 도입하고 있다. 또한 내열 타이타늄 합금, 금속간화합물과 같은 고온재료가 개발됨에 따라 고가의 차종에는 신재료가 이들 부품으로 채용되고 있다. 이 글에서는 배기계 부품의 설계적인 요소에 의한 열적, 기계적 측면의 내구 특성을 살펴보고, 이들 부품에 보편적으로 적용되는 고온 금속재료의 종류 및 기계적 특성을 소개하였다. 아울러 미래의 환경친화적 자동차용 고온 부품을 개발하기 위하여 연구되고 있는 Super Si+MO, 스테인리스 강, TiAl, 고온 타이타늄 합금 등과 같은 자동차 내열 부품으로 사용되는 신소재의 연구개발 동향에 관하여 기술하였다.

• Journal of the Korean Institute of Gas
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• v.16 no.2
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• pp.45-51
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• 2012

The MSITs(Minimum Spontaneous Ignition Temperatures) or AITs(Autoignition Temperatures) describe the minimum temperature to which a substance must be heated, without the application of a flame or spark, which will cause that substance to ignite. This study measured the MSITs(Minimum Spontaneous Ignition Temperatures) of n-pentanol+ethylbenzene system by using ASTM E659 apparatus. The MSITs of pure n-pentanol and ethylbenzene were $285^{\circ}C$ and $475^{\circ}C$, respectively. The experimental MSITs of n-pentanol+ethylbenzene system were a in good agreement with the MSIT calculated by the proposed equations with a few A.A.D.(average absolute deviation).

• Journal of the Korean Institute of Gas
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• v.17 no.5
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• pp.69-74
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• 2013

The study was conducted experimentally on characteristic of thermal decomposition and minimum ignition temperature of magnesium dusts. For this purpose, three different Mg dusts of mean diameter (38, 142, $567{\mu}m$) were used. Experimental investigations were conducted by using TGA(Thermo gravimetric analysis) and MIT(Minimum Ignition Temperature) apparatus made in accordance with IEC 61241-2-1 standard. As the results, temperature of weight gain in Mg dust layers increased with increasing of heating rates in air and, under the same heating rate condition, minimum ignition temperature increased with particle size. Also the MIT of suspended Mg dust clouds tended to increase with increasing of mean diameter.