• Journal of Elementary Mathematics Education in Korea
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• v.20 no.2
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• pp.215-238
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• 2016

The 2015 national revised curriculum was notified officially the last year. The intent and direction of the revision caused more or less change for mathematical contents to be taught and is expected to cause a considerable change in math class. In the level of elementary school mathematics, it turned that several contents were deleted or moved to the upper grades because the revision focused especially both on reducing students' burden of learning and on fostering the mathematical key competences. This study aims to examine the relevance of the change through investigation of the national curriculums for elementary school mathematics since 1946. The mathematical contents to be analyzed in this study were mixed calculation of natural numbers, mixed calculation of fractions and decimal fractions, position and direction of objects, are/hectare and ton, the range of numbers and estimating, surface and volume of cylinders, pattern and correspondence, and direct/inverse proportionality, which were changed in any aspect relative to 2009 national revised curriculum. Based on the results of these analyses, the discussion will provide some suggestions for setting the direction of elementary mathematics curriculum.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.4
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• pp.81-99
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• 2015

The acceleration of global warming has required better understanding of carbon cycles over local and regional areas such as the Korean peninsula. Since forests serve as a carbon sink, which stores a large amount of terrestrial carbon, there has been a demand to accurately estimate such forest carbon sequestration. In Korea, the National Forest Inventory(NFI) has been used to estimate the forest carbon stocks based on the amount of growing stocks per hectare measured at sampled location. However, as such data are based on point(i.e., plot) measurements, it is difficult to identify spatial distribution of forest carbon stocks. This study focuses on urban areas, which have limited number of NFI samples and have shown rapid land cover change, to estimate grid-based forest carbon stocks based on UNFCCC Approach 3 and Tier 3. Land cover change and forest carbon stocks were estimated using Landsat 5 TM data acquired in 1991, 1992, 2010, and 2011, high resolution airborne images, and the 3rd, 5th~6th NFI data. Machine learning techniques(i.e., random forest and support vector machines/regression) were used for land cover change classification and forest carbon stock estimation. Forest carbon stocks were estimated using reflectance, band ratios, vegetation indices, and topographical indices. Results showed that 33.23tonC/ha of carbon was sequestrated on the unchanged forest areas between 1991 and 2010, while 36.83 tonC/ha of carbon was sequestrated on the areas changed from other land-use types to forests. A total of 7.35 tonC/ha of carbon was released on the areas changed from forests to other land-use types. This study was a good chance to understand the quantitative forest carbon stock change according to the land cover change. Moreover the result of this study can contribute to the effective forest management.

• Journal of the Korean Institute of Landscape Architecture
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• v.14 no.2
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• pp.7-16
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• 1986

This study was carried out to investigate the effects of such erosion control measures as sowing, planting and small earth structures on the soil and vegetation. In order to study the changes in soil and vegetation, 36 plots were surveyed from 1981 to 1982 in the large erosion control area which is restored last 20 years. The factors which were measured included vegetation coverage, tree growth, number of species, soil depth, soil consistancy, and Chemical properties of soil. The results were as follows; 1) Maximum coverage of the overstory and understory was attained 7 years after the initiation of erosion control. So the overstory need to be tended and pruned. 2) Diversity of species increased until age 6 after which it began to decrease. 3) In order of tree growth, black locust was the fastest, followed by siberian alder and pitch pine. The initial growth of black locust, though the best among the 3 tree stop., decreased rapidly year by year. At the same time, siberian alder and pitch pine grew well until 12 and 6 years after the initiation of erosion control respectively. 4) Fifty percent of the initially planted trees died within 8 yeard. The mortality of siberian alder occurred until the 20th year while the mortality of pitch pine stopped after 10 years. Thereafter 500 trees per hectare were maintained. 5) The soil depth in A and B horision increased by 2cm annually during 20 years. The soil consistency also decreased rapidly until 7th year. The physical soil properties of the rehabilitated areas were improved after the 14th year. 6) The soil pH tend to decrease from 5.3 during the first year to 5.1 during the twentieth year. 7) The organic matter and nitrogen content in the soil were increased by fertilization but after 20 years these nutrients are still deficient for normal tree growth. 8) The phosphorous content in the soil was high in the first year but the longer the period after the initiation of erosion control the lese the content of phosphorous. 9) The biomass of black locust was the highest and increased continuously. The biomass of siberian alder on the contrary decreased from the 15th year because the number of trees in this place was very low. The total biomass in the twentieth year after erosion control initiation was 105.7 ton per hectare.

• Korean Journal of Breeding Science
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• v.41 no.2
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• pp.158-162
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• 2009

"Wonkwang" is a new sprout-soybean cultivar developed from the cross between Danyeobkong and MS91001 at the Honam Agricultural Research Institute (HARI) and National Institute of Crop Science (NICS), RDA, in 2007. The preliminary, advanced and regional yield trials to evaluate the performance of Iksan 56 were carried out from 2003 to 2007. This cultivar has a determinate growth habit, purple flower, grayish brown pubescence, yellow seed coat, Grayish brown hilum, lanceolate leaflet shape and small seed size (10.9 g/100 seeds). The maturity date of "Wonkwang" is three days later than the check variety, "Pungsan". It has a good seed quality for soybean-sprout and resistance to lodging. The soybean-sprouts grown from "Wonkwang" have high isoflavone ($3,481{\mu}g/g$)contents. This cultivar has resistance to soybean mosaic virus (SMV) and necrotic symptom (SMV-N) and other most troublesome soybean diseases which are bacterial pustule and black root rot. The grain yield of "Wonkwang"in the regional yield trials (RYT) for 3 consecutive years was averaged 3.05 ton per hectare, which was 8% higher than that of the check cultivar "Pungsan".

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.2
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• pp.67-73
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• 1979

The effect of liming on the potassium equilibrium activity ratio ($AR^k_e$) of Chinese cabbage cultivated soil and on the potassium uptake by the plant summarize as follows: 1. $AR^k_e$ is raised by the application of 1.6 ton of $Ca(OH)_2$ per hectare that required amount to adjust pH 6 for the soil. Generally, it could be confirmed that both liming and potassium placement to the soil show the combined effects to raise $AR^k_e$. 2. The exchangeable potassium and the electrical conductivity increase by liming. The mean value of the exchangeable potassium is 0.71 m. equ. per 100g of limed soils while the control give 0.64 m. equ. per 100g. For the electrical conductivity, limed soil show $766{\mu}mho$ and $750{\mu}mho$ is for the control. 3. The reason $AR^k_e$ value increase by liming could be considered that concentrations of $K^+$ and $Ca^{{+}{+}}+Mg^{{+}{+}}$ in the equilibrium solution are increased owing to release both K and $Ca^+$ Mg into the liquid from solid phase in the potassium equilibrium system of the soil. 4. For considering that the energies of exchange of calcium by potassium in the limed soils at different potassium treatment, that is without K, 200 kg $K_2O/ha$ and 350 kg $K_2O/ha$, give -3887 and -3778 and -3737 calories per chemical equivalent respectively. On the other hand in case of the controls which received the same amounts of potassium as mentioned above, energy values are -3983, -4392 and -4228 calories respectively. 5. The absorbed amount of potassium and weights of dry matters of the plant which grown in the limed soils show little higher values than the controls.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.640-644
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• 2009

A new sprout-soybean cultivar, "Sohwang" was developed at the National Institute of Crop Science (NICS) in 2008. "Sohwang" was selected from a cross between Pungsan and Pungsan/Nattosan. The preliminary, advanced, and regional yield trials to evaluate the performance of Iksan 58 were carried out from 2004 to 2008. This cultivar has a determinate growth habit with purple flower, grayish brown pubescence, yellow seed coat, Yellow hilum, lanceolate leaflet shape and small seed size (8.5 grams per 100 seeds). The maturity date of "Sohwang" is 10 days earlier than the check variety, "Pungsan". It has a good seed quality for soybean-sprout. The soybean-sprouts grown from "Sohwang" have high isoflavone ($3,041{\mu}g/g$)contents. This cultivar has resistance to soybean mosaic virus (SMV) and necrotic symptom (SMV-N), and other most troublesome soybean diseases which are bacterial pustule and black root rot. Especially, "Sohwang" has useful characteristics, such as lodging and shattering resistance. The average yield of "Sohwang" was 2.69 ton per hectare in the carried out for three years from 2006 to 2008 regional yield trials(RYT) for double cropping.