• Animal Bioscience
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• v.34 no.1
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• pp.36-47
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• 2021

Objective: This study determined the optimal ratio of whole plant corn silage (WPCS) to corn stover (stems+leaves) silage (CSS) (WPCS:CSS) to reach the greatest profit of dairy farmers and evaluated its consequences with corn available for other purposes, enteric methane production and milk nitrogen efficiency (MNE) at varying milk production levels. Methods: An optimization model was developed. Chemical composition, rumen undegradable protein and metabolizable energy (ME) of WPCS and CSS from 4 cultivars were determined to provide data for the model. Results: At production levels of 0, 10, 20, and 30 kg milk/cow/d, the WPCS:CSS to maximize the profit of dairy farmers was 16:84, 22:78, 44:56, and 88:12, respectively, and the land area needed to grow corn plants was 4.5, 31.4, 33.4, and 30.3 ha, respectively. The amount of corn available (ton DM/ha/yr) for other purposes saved from this land area decreased with higher producing cows. However, compared with high producing cows (30 kg/d milk), more low producing cows (10 kg/d milk) and more land area to grow corn and soybeans was needed to produce the same total amount of milk. Extra land is available to grow corn for a higher milk production, leading to more corn available for other purposes. Increasing ME content of CSS decreased the land area needed, increased the profit of dairy farms and provided more corn available for other purposes. At the optimal WPCS:CSS, MNE and enteric methane production was greater, but methane production per kg milk was lower, for high producing cows. Conclusion: The WPCS:CSS to maximize the profit for dairy farms increases with decreased milk production levels. At a fixed total amount of milk being produced, high producing cows increase corn available for other purposes. At the optimal WPCS:CSS, methane emission intensity is smaller and MNE is greater for high producing cows.

• Tribology and Lubricants
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• v.37 no.6
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• pp.232-239
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• 2021

Petroleum is the most consumed energy source in Korea with a usage rate of 38.7% among the available primary energy sources. The price of liquid petroleum products in Korea includes taxes such as transportation·environment·energy tax. Thus, illegal production and distribution of liquid petroleum is widespread because of its huge price difference from that of the normal product and its tax-free nature. Generally, the illegal petroleum product is produced by mixing liquid petroleum with other similar petroleum alternatives. The two kinds of gasoline, common gasoline and premium gasoline, are being distributed in Korea. The premium gasoline is often adulterated with cheaper common gasoline that lowers the octane number of gasoline. It is possible to distinguish them with their color difference, green and yellow for different grade gasoline. However, when small volume of common gasoline is added to premium gasoline, it is difficult to determine whether premium gasoline contained common grade or not. In this study, we inspect gasoline, which is illegally produced by mixing common gasoline to premium gasoline. When the ratio of mixing common gasoline is increased, premium gasoline shows decreasing absorbance at 600 nm and 650 nm under UV-Vis spectrometer. Moreover, the detected intensity (mV·s) of green dye in high performance liquid chromatography (HPLC) was decreased by common gasoline under 0.99 correlation value. The more the common gasoline is mixed, the more olefin and naphthene are detected by gas chromatography. In addition, trimethyl pentane as octane improver, paraffin and toluene are decreased by common gasoline mixing. The findings of this study suggests that illegal petroleum can be identified by analysis of components and simulated samples.