• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.46-55
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• 2016

The kinetic analysis of a heavily aluminized cyclotrimethylene-trinitramine(RDX) is conducted using differential scanning calorimetry(DSC), and the Friedman isoconversional method is applied to the DSC experimental data. The pre-exponential factor and activation energy are extracted as a function of the product mass fraction. The extracted kinetic scheme does not assume multiple chemical steps to describe the complex response of energetic materials; instead, a set of multiple Arrhenius factors is constructed based on the local progress of the exothermic reaction. The resulting reaction kinetic scheme is applied to two thermal decomposition tests for validating the reactive flow response of a heavily aluminized RDX. The results support applicability of the present model to practical thermal explosion systems.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.131-138
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• 2003

This paper considered the structural mechanism of transitional boundary layer by the experimental approach. In order to measure the turbulence quantity in the boundary layer, we made a wind tunnel with 400${\times}$190${\times}$2500 mm test section and a flat plate with well fabricated leading edge. Hot wire anemometer was used for acquiring the continuous turbulence signal which is processed by special software. The results of experiment show that the region where turbulence spot is dominant moves from near wall to overall layer and thus the anisotropy of velocity fluctuation shows so large value. Also the turbulence energy originally contained in low frequency band comes up to the high frequency band. Finally the turbulence model needs minimum two length scales to consider the pre-transition region.

• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.820-826
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• 1988

The freezing point$(t_f)$, latent heat of freezing$({\triangle}\;H_f)$ and kinetic constant of fleering$(k_f)$ were determined from DSC thermogram at cooling rate $-2.5^{\circ}C/min{\sim}-10.0^{\circ}C/min$. The freezing point of various starches was decreased with an increase in cooling rate, and that of whole starches were lower than defatted starches. Changes of the latent heat of freezing was not observed at above cooling rate $-2.5^{\circ}C/min$. The latent heat of freezing$({\triangle}\;H_f)$ could be deduced as a function of water content(W) as follows: ${\triangle}\;H_f=0.700W-13.048$, (Kcal/kg) $(35%{\leqq}W{\leqq}70%)\;{\triangle}\;H_f=1.569W-73.861,\;(Kcal/kg)\;(W{\geqq}70%$) In the water content range $35{\sim}90$(wt %), the activation energy of various starches in freezing process was determined $126{\sim}270$ Kcal/mol.

• Journal of the Korean Vacuum Society
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• v.13 no.1
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• pp.14-21
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• 2004

It is essential to increase the switching speed of power devices to reduce the energy loss because high frequency is commonly used in power device operation these days. In this work electron irradiation has been conducted to reduce the lifetime of minority carriers and thereby to increase the switching speed of a$p^+- n^-$ junction diode. Effects of electron irradiation on the electrical properties of the diode are reported The switching speed is effectively increased. Also the junction leakages and the forward voltage drop which are anticipated to increase are found to be negligible in the $p^+- n^-$ junction diodes irradiated with the optimum energy and dose. The analysis results of DLTS and C-V profiling indicate that the defects induced by electron irradiation in the silicon substrate are donor-like ones which have the energy levels of 0.284 eV and 0.483 eV. Considering all the experimental results in this study, it might be concluded that electron irradiation is a very useful technique in improving the switching speed and thereby reducing the energy loss of $p^+- n^-$ junction diode power devices.

• 보일러설비
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• s.58
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• pp.48-61
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• 1998

• Product Safety
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• s.182
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• pp.88-89
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• 2009

• 보일러설비
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• s.46
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• pp.65-78
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• 1997

• Intergrated Energy Industry
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• s.1
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• pp.66-67
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• 2005

• Korea Petroleum Association Journal
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• no.12 s.190
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• pp.71-73
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• 1996

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.05a
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• pp.485-493
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• 2003

2승 저감 형태의 부하특성을 갖는 공조용 팬이나 물을 순환시키는 펌프를 구동하는 전동기는 일반적으로 전원전압을 직입하여 사용한다. 따라서 전원 주파수인 60Hz가 회전속도의 기준이 되어 4극인 유도전동기를 예를 든다면 기준속도가 1800[rpm]이 되며, 이 속도는 부하 조건과 관계없이 운전되면서 경부하 조건에서는 불필요한 에너지를 많이 소모하는 원인이 되어왔다. 이런 문제점은 부하에 맞추어 속도를 제어해 줌으로써 소모전력을 현격히 줄일 수 있는데 이를 위해 일반적으로 인버터를 사용한다. 그런데 인버터에 대해서는 KS 기준이 없어 개인별 또는 기업체별로 가지고 있는 평가기준을 활용하여 인버터를 개발해 왔다. 이에 본 논문에서는 인버터 보급을 촉진시키기 위한 관련 정책을 분석하고 인버터에 대한 기술기준을 제시하여 인버터 평가기준을 보급하고자 한다.