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Cu - Co - Cr 계 촉매에 의한 Alcohol 합성연구
엄태윤,하백현,박건용 한국화학공학회 1983 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.21 No.6
Copper, Cobalt, Chrome 酸化物에 Potassium oxide가 알칼리로서 添加된 觸媒를 製造하였으며, X-線회절분석 결과 結晶性이 낮은 Cupric oxide와 Cobalt chromite의 混合物에 가까운 特性을 나타내었고 BET 表面積은 19.5㎡/g이었다. 이 觸媒는 Carbon monoxide와 Hydrogen으로부터 低溫, 低壓에서 Methanol을 주로 Alcohols의 合成에 좋은 活性을 보여 주었으며 300℃ 이상에서는 많은 higher alcohols을 生成시킬 수 있음을 보여 주었다. 反應의 機構는 Trimolecular surface reaction을 rate determining step으로 한 Langmuir-Hinshelwood mechanism으로 表現했을 때 잘 一致하였으며 280℃에서의 速度式은 다음과 같이 表現할 수 있었다. (수식) 여기서 f^는 各가스成分의 fugacity를 나타내고 K_(eq)는 反應平衡常數, A, B, C, D는 實驗的으로 求해진 常數값을 나타낸다. We came up with a system of catalysts that can be useful in manufacturing methanol and higher alcohols from carbon monoxide and hydrogen at low temperature and pressure. These were prepared by adding alkaline potassium oxide to a mixture of oxides of copper, cobalt and chrome. The BET measurements of the catalysts 9ave 16.5㎡/g for surface area and the X-ray diffraction data indicated the presence of partly crystalline cupric oxide and cobalt chromite mixture. The activity was relatively high for the formation of methanol and, at temperatures higl1erthan 300℃, C₂, C₃ and C₄ alcohols were also produced. The reaction was closely described by the Langmuir-Hinshelwood mechanism, in which the rate determining step was assumed to be the trimolecular surface reaction. Thus we could write the rate of reaction at 280℃ as (수식), where f^ denotes the fugacity of each gas, K_(eq) the equilibrium constant and A, B, C, D empirical constants.
심층신경망과 천리안위성 2A호를 활용한 지상기온 추정에 관한 연구
엄태윤,김광년,조용한,송근용,이윤정,이윤곤 대한원격탐사학회 2023 大韓遠隔探査學會誌 Vol.39 No.2
This study suggests deep neural network models for estimating air temperature with Level1B (L1B) datasets of GEO-KOMPSAT-2A (GK-2A). The temperature at 1.5 m above the ground impactnot only daily life but also weather warnings such as cold and heat waves. There are many studies toassume the air temperature from the land surface temperature (LST) retrieved from satellites becausethe air temperature has a strong relationship with the LST. However, an algorithm of the LST, Level 2output of GK-2A, works only clear sky pixels. To overcome the cloud effects, we apply a deep neuralnetwork (DNN) model to assume the air temperature with L1B calibrated for radiometric and geometricsfrom raw satellite data and compare the model with a linear regression model between LST and airtemperature. The root mean square errors (RMSE) of the air temperature for model outputs are used toevaluate the model. The number of 95 in-situ air temperature data was 2,496,634 and the ratio of datasetspaired with LST and L1B show 42.1% and 98.4%. The training years are 2020 and 2021 and 2022 isused to validate. The DNN model is designed with an input layer taking 16 channels and four hiddenfully connected layers to assume an air temperature. As a result of the model using 16 bands of L1B, theDNN with RMSE 2.22°C showed great performance than the baseline model with RMSE 3.55°C onclear sky conditions and the total RMSE including overcast samples was 3.33°C. It is suggested that the DNN is able to overcome cloud effects. However, it showed different characteristics in seasonal andhourly analysis and needed to append solar information as inputs to make a general DNN model becausethe summer and winter seasons showed a low coefficient of determinations with high standard deviations.
엄태윤,김필성 한국군사과학기술학회 2002 한국군사과학기술학회지 Vol.5 No.3
A target adaptive guidance(TAG) algorithm is proposed employing the near-zone signal that can be measured from an infrared seeker. The guidance order is composed of a conventional PNG command and an additional command to be calculable from an additional LOS rate between a hot point of target and a required intercept point. The characteristic of the near-zone signal is similar to that of LOS rate that is inversely proportional to the square of time-to-go. Hence the proposed scheme can be applied to real systems with no estimator for time-to-go. From analysis results on the miss distance with perfect missile and perfect seeker, it follows that the proposed TAG algorithm guarantees missile to be ideally guided to the required intercept point. And it is less affected by the TAG start time and a proportional navigation ratio than other TAG schemes using a LOS rate such as a step bias or a ramp bias.