• 한국응용과학기술학회지
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• 제8권2호
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• pp.145-151
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• 1991

Hazadous properties were evaluated for Alkyl nitrates such as hexyl nitrate, decyl nitrate, dodecyl nitrate and 2-methyl pentyl nitrate, 2-hexyl ethyl nitrate. The thermochemical properties such as heat of vaporization, boiling point, flash point and kinetic parameter for aliphatic nitrate were measured to determine the hazadous properties of these compounds. The boiling points and heat of vaporization increase as the increase of alkyl chain length in alkyl nitrates. Flash point is a linear function of boiling point as same as alkanes. The rate equation in isothermal decomposition are 1/2 order and compensation effect is found between logarithm of frequency factor the activation energy, then the decomposition preceeds with simlar reaction mechanism for each nitrate.

• 한국분무공학회지
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• 제28권2호
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• pp.89-96
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• 2023

This study presents a numerical simulation investigating hydrodynamic characteristics of high-temperature hydrocarbon aviation fuel injected through a plain orifice injector. The analysis encompassed the temperature range up to the critical point, and the obtained results were compared with prior experimental observations. The analysis unveiled that the injector's exit pressure remains equivalent to the ambient pressure when the fuel injection temperature is below the boiling point. However, when the fuel temperature surpasses the boiling point, the exit pressure of the injector transitions to the saturated vapor pressure corresponding to the fuel injection temperature. Consequently, the exit pressure of the injector increases in tandem with the rapid increase of the saturation vapor pressure due to escalating fuel temperatures. This rise in the exit pressure necessitates a proportional increase in fuel injection pressure to ensure a fixed fuel mass flow rate. Furthermore, the investigation revealed that the discharge coefficient obtained by applying the exit pressure instead of the ambient pressure did exhibit no decrease, but rather was maintained at a nearly constant value, comparable to its level below the boiling point.

• Nuclear Engineering and Technology
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• 제35권4호
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• pp.274-285
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• 2003

Film boiling heat transfer coefficients for a downward-facing hemispherical surface are measured from the quenching tests in DELTA (Downward-boiling Experimental Loop for Transient Analysis). Two test sections are made of copper to maintain Bi below 0.1. The outer diameters of the hemispheres are 120 mm and 294 mm, respectively. The thickness of both the test sections is 30 mm. The effect of diameter on film boiling heat transfer is quantified utilizing results obtained from the two test sections. The measured heat transfer coefficients for the test section with diameter 120 mm lie within the bounding values from the laminar film boiling analysis, while those for diameter 294 mm are found to be greater than the numerical results on account of the Helmholtz instability. There is little difference observed between the film boiling heat transfer coefficients measured from the two test sections. In addition, the higher thermal conductivity of copper results in the higher minimum heat flux in the tests. For the test section of diameter 120 mm, the Leidenfrost point is lower than that for the test section of diameter 294 mm. Destabilization of film boiling propagates radially inward for the 294 mm test section versus radially outward for the 120 mm Test Section.

• 한국안전학회지
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• 제13권4호
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• pp.192-198
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• 1998

MRSM(modified response surface methodology)-2 model is presented for the prediction of boiling points in combustible solution of quaternary systems. This model requires only normal boiling points of pure substances and group-group parameters which are based on the group-group concepts without the use of experimental data under consideration. By means of this methodology, it is possible to predict the boiling points of the combustible mixture of quaternary systems by plotting of isothermal lines using computer graphics. The proposed methodology has been tested and compared successfully with reported boiling points in journals for the combustible solution of quaternary systems. It is hoped eventually that this methodology will permit prediction of the flash point and flammability limit for the combustible mixture of multicomponent systems.

• Journal of Advanced Marine Engineering and Technology
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• 제32권5호
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• pp.707-716
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• 2008

The objective of this study was to analyze the effect of mixed fuel composition and mass fraction on spray inner structure in evaporating transient spray under the variant ambient conditions. Spray structure and spatial distribution of liquid phase concentration were investigated using a thin laser sheet illumination technique on the three component mixed fuels. A pulsed Nd:YAG laser was used as a light source. The experiments were conducted in a constant volume vessel with optical access. Fuel was injected into the vessel with electronically controlled common rail injector. Used fuel contains i-octane($C_8H_{18}$), n-dodecane($C_{12}H_{26}$) and n-hexadecane($C_{16}H_{34}$) that were selected as low-, middle- and high-boiling point fuel, respectively. Experimental conditions are 42 MPa, 72 MPa and 112 MPa in injection pressure, $5\;kg/m^3$, $15kg/m^3$ and $30kg/m^3$ in ambient gas density, 300 K, 500 K, 600 K and 700 K in ambient gas temperature, 300 K and 368 K in fuel temperature and different fuel mass fraction. Experimental results indicated that the multi-component fuels made two phase region mixed vapor and liquid so that it would are helpful to improve combustion, for the fuels of high boiling point component could accelerate evaporation very much according as low boiling point fuel was added to high boiling point fuel.

• 센서학회지
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• 제22권6호
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• pp.404-409
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• 2013

We devised calibration procedure for industrial thermometers by a comparison method at the boiling point of nitrogen (${\sim}-196^{\circ}C$). The uncertainty of the calibration was 4 mK (k = 2). As experimentally demonstrated in this work, the effect of the atmospheric pressure on the boiling point of nitrogen can be easily detected by the thermometer. Therefore, when the boiling point of nitrogen is used for calibration of thermometer by comparison, either a reference thermometer must be used to provide the reference temperature or the effect of atmospheric pressure should be carefully considered. The use of a copper block with a large thermal mass soaked into the liquid nitrogen was proven to be more reliable, and the stability of the temperature immersed into the copper block was 1.4 mK. The temperatures at the thermometer wells, evaluated by the crossed-measurement method to compensate for the inaccuracy of the thermometers and the linear drift of the temperature of the copper block, were equivalent within 0.23 mK of standard uncertainty.

• 한국과학교육학회지
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• 제26권7호
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• pp.805-812
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• 2006

본 연구에서는 끓는점 오름에 대한 고등학교 화학 교과서의 기술 양식과 고등학생, 예비교사, 고등학교 화학교사의 이해에 대하여 조사하였다. 6차와 7차 교육과정에 근거하여 개발된 고등학교 화학 II 교과서를 분석하였고 고등학생과 예비교사, 화학교사의 개념은 설문지를 통해 얻었다. 끓는점 오름의 원인에 대한 교과서의 설명 유형은 '표면의 용매 입자수의 감소', '용매-용질간의 인력', 그리고 '표면 입자수의 감소와 용매-용질간의 인력'등의 세 가지 유형으로 분석되었다. 개념조사 결과 '용매-용질간의 인력'을 끓는점 오름의 원인으로 인식하는 학생과 예비교사, 화학교사의 비율이 높았다. 대상자들은 끓는점 오름을 설명하기 위하여 엔트로피 개념보다 엔탈피 개념을 선호하는 경향이 있었고, 그 원인을 분석하기 위하여 사후 인터뷰를 실시하였다.

• 한국환경보건학회지
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• 제32권4호
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• pp.262-267
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• 2006

DBPs and T&O(taste-and-odor) compounds in drinking water is one of main source to deteriorate water quality. So, these compounds can cause adverse health effects and result in many consumer complaints aesthetically. This experiments carried out to investigate the effect of boiling water on DBPs and T&O compounds in the tap water. THMs and TCM concentration were reduced by 91.3%, 88.9% after 5 min of boiling, respectively. It is certainly, resulted from volatilization of TCM. TCAA concentration decreased when the water was boiled, too. By contrast, the concentration of DCAA was increased with duration time from boiling-point. The reduction of TCAA from the boiled water can be attributed to chemical transformation like decarboxylation. T&O compounds such as geosmin and 2-MIB was effectively removed by boiling of water, resulting in the removal efficiency of 97.1%, 94.4% after 5 min of boiling, respectively.

• 청정기술
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• 제19권3호
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• pp.233-242
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• 2013

PVC 함유 가연성폐기물의 열분해시 Ca 계열 및 Fe 계열 산화물을 탈염 흡수제로 사용하여 생성물의 분포, 액상 생성물의 비점분포, 생성물의 염소 농도에 미치는 영향을 조사하였다. Fe 계열 산화물 분말을 액상에서 흡수제로 사용시 오일의 수율이 뚜렷하게 감소하였다. 이러한 현상은 산화철이 열분해시 일부 열분해 촉매의 역할을 하였을 가능성을 나타낸다. 반면에 오일의 비점분포가 낮아지는 현상은 발견되지 않았으며 이러한 현상은 산화철의 촉매 반응성이 크지 않기 때문으로 보인다. Ca 계열 산화물 분말을 흡수제로 사용한 경우 오일 수율이 감소하는 현상은 발견되지 않았으며 비점분포도 큰 변화가 없었으나 탈염성능이 산화철 분말 흡수제 보다 더 우수하였다.

• 한국식품과학회지
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• 제23권5호
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• pp.605-609
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• 1991

과일쥬스의 농축공정 중 고려되어야 할 중요한 공학적 물성치로는 비점상승, 밀도, 점도 등이다. 이들 물성치는 식품성분에 따라 고유한 특성을 나타내며 고형분의 함량, 압력, 온도에 따라 변화한다. 따라서 본 논문에 있어서 비점상승에 영향을 미치는 고형분의 함량과 압력에 대한 비점상승을 측정하였고 이에 따른 예측 모델식을 수립 하였다. 비점 상승도는 조작압력 및 고형분 함량을 독립변수로 하여 추정된 몇 가지 함수식으로부터 SPSS 통계 package 중 regression program을 이용하여 단순 회귀시켜 R값이 가장 높은 모델식을 택하였다. 또한 밀도는 고형분 함량에 따라 점도는 온도와 고형분 한량에 따라 예측 모델식을 각각 수립하였다.