• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.80-84
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• 1999

$Li_{4/3}Mn_{5/3}O_4$ having a defect structure was prepared by sol-gel process using lithium acetate and manganese acetate as starting materials, and their electrode characteristics in the lithium secondary battery was investigated. The reaction mole ratio was determined as $AA/Mn(OAc)_2$ of 0.2 and $NH_4OH/Mn(OAc)_2$ to $H_2O/Mn(OAc)_2$ of 0.4. The product was obtained through heat treatment at $350^{\circ}C$ for 12hrs after 1'st heat treatment at $150^{\circ}C$ of xerogel under oxygen atmosphere. When the charge and discharge cycles were performed between 2.0 V and 3.2 V, $Li/Li_{4/3}Mn_{5/3}O_4$ cell showed the dicharge capacity of 84.23 mAh/g and the good cycleability was obtained in the plateau region.

• Bulletin of the Korean Chemical Society
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• v.29 no.9
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• pp.1815-1818
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• 2008

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.4
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• pp.275-280
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• 1990

In order to obtain the basic informations on the reasonable fertilization and soil management systems for a high soybean yield, both soybean leaves and soils were collected from 24 soybean-cultivated fields in central area of Korea, and analyzed. For this study, soybean leaves and soil were sampled together in July of 1988(growing season), and soil alone in October of 1988 (harvesting season) and April of 1989(sowing season) at each sampling site. The results might be summarized as follows: 1. The soil pH ranged between 4.8 and 6.8. and the pH after harvest decreased to 5.4 which compared with the pH 5.7 of growing season. 2. Both the 1N KCl extractable Al and the 1N $NH_4OAc$ extractable Al in soils were inversely correlated with the soil pH. the former concentration was negligible above pH 5.8. 3. The soil total-N and Bray 1-P after harvest were lower than those of growing season. The Bray 1-P's of sample soils were very high irrespective of sampling time. 4. The exchangeable Ca and Mg in soils even after harvest varied little whereas the exchangeable K decreased with time. 5. The N content in soybean leaves was not correlated with soil total-N, but highly correlated with the K content in soybean leaves. The Mg content in soybean leaves was also highly correlated with Ca content in suybean leaves and exchangeable Mg in soils.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.2
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• pp.99-105
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• 1976

After investigation of soil characteristics the properties of a reclaimed marine soil (Gupo series) distributed along the southern coastal areas of Korea are summarized as follows: 1. Gupo soils distributed in the southern Ria coastal area are derived from rolling to hilly materials and are poorly sorted with less influences of river fluvial action. These soils have high content of sand compared with the broad fluvio-marine soils in the western coastal areas. 2. The morphological features of the poorly drained Gupo soils are greyish brown sandy loam with a few yellowish mottles in the surface horizon and are grey sandy loam with a few gravel in the sub-strata. The ground water table remains around 10-30cm below the surface. These soils, recently reclaimed younger deposits, do not show any evidence of illuviation. 3. The "n" value (about 0.8) of the Gupo soils indicates physically unripened soils. 4. pH value of these soils shows more than 8.0 throughout the profile. Organic matter contents are extremely low (around 0.5%) except 1.2 percent in the surface horizon. C.E.C. ranges from 7 to 9m.e/100g which is lower than average in the country. The ratios of extractable cations such as Ca, Mg, Na and K of the surface horizon are 20:7:4:1. Base saturation is more than 60%. Available phosphate content is very low that is less than 25 ppm. Electric conductivity of the soils at $25^{\circ}C$ ranges 7 to 12 mmhos/cm and increased with depth. 5. According to classification of soil based on physical ripening, the Gupo soils can be classified into "Unripe soils with half-ripe sub-soils". The soils could be classified into "Hydric Haplaquents" in the original of the 7th Approximation (1960), but into "Typic Haplaqents in the supplement of 7th approximation which the physical ripening condition is not clearly expressed. Soil Taxonomy, apparently the final version of the 7th approximation, defines the soils as "Haplic Hydraquents" that clearly show the condition of physical ripening as well as other properties. Other several classification systems applied do not describe physical ripening condition of the soils.