• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.514-527
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• 2007

Earth reinforcement techniques are used worldwide and offer proven solutions to a wide range of geotechnical engineering problems. Here in this paper, recent developments of three major reinforced soil retaining wall methods in Japan were introduced in order to show how the current situation of this technique in Japan is. And the statistical data for the volume of the use was also shown, such as the total volume of the use, the scales of the structures, layout of the earth reinforcement, fill materials, and foundation conditions. Some of the case histories were also introduced with photographs and figures. And then, as one of recent research activity by the author, the study on the application of X-ray CT for the problem of earth reinforcement method combined with other method such as piling and soil improvement was introduced. In this study, a series of model test for several reinforced ground with geogrids was conducted using a newly developed test apparatus. Then, the behavior in the soil box was scanned after settlement using X-ray CT scanner. Based on these test results, the reinforcing effect by the geogrids and the soil arching effect over the pile heads was discussed precisely and those are done in 3-D with nondestructive condition. Finally, the effectiveness of the use of X-ray CT scanner in geotechnical engineering was promised.

• Journal of Korea Soil Environment Society
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• v.1 no.1
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• pp.81-88
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• 1996

To study the Cd adsorption in the presence of competing ions in soil-solution interphase, three soil samples from the Bt horizon were taken and analyzed for their physical and chemical properties. Adsorption of ethylene glycol monoethyl ether(EGME) and N, were determined to establish the specific surface area of the soils. We attempted to establish a qeneralizing competitive sorption isotherms for soils of entirely different composition of the solid phase, resulting in the routine use as a guidelines for the fate of reactive solute in soil profiles. Many physicochemical factors including competitive adsorption bettween solutes will affect the general adsorption phenomena as shown in a single not only on the soil:solution ratio used, but also on the surface areas of its respective soil samples. This phenomenon was attributed to competition Cd for sorption sites with Mg by different soil constituents. These adsorption isotherms are able to use as examples to demonstrate that this phenomenon can complicate the development of a standardized batch adsorption procedure as well as interpreting fate and adsorption of toxic inorganic compounds.

• Journal of the Mineralogical Society of Korea
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• v.15 no.2
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• pp.114-121
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• 2002

Buffer capacities for two Bo horizon soils or Andisols developed from different parent materials have been investigated. The titration curves from column leaching experiment show that buffering occurred at pH 4.0 and 6.0. The buffer intensity or soil developed from pyroclastic materials (P-soil) is higher than that from basalts (B-soil). From batch test we have found that proto-imogolite and/or imogolite may control Al solubility as well as $Al(OH) _3$in the moderate acid condition. The buffer intensities ($\beta$) of P-soils were plotted on the theoretical buffering curve of $Al(OH)_3$, while $\beta$ of B-soils approached to that of proto-imogolite, which shows the solubility of short-range-order materials in P-soil control the buffer capacity. Buffering at pH 6.0 is thought to be the result of dissolution of some silicate clays and exchange reactions between $H^{+ }$and base-forming cations. Considering the amount of annual acid precipitation, aluminum solubility of Andisols, and the low BS (Base Saturation percentage), it can be predicted that prolonged acid precipitation will reduce the buffer capacity of soils and lead to soil acidification.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.2
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• pp.97-104
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• 1979

According to Soil Taxonomy which has been developed over the past 20 years in the soil conservation service of the U. S. D. A, Soils in Korea are classified. This system is well suited for the classification of the most of soils. But paddy field soils have some difficulties in classification because Soil Taxonomy states no proposals have yet been developed for classifying artificially irrigated soils. This paper discusses some problems in the application of Taxonomy and suggestes the classification of paddy field soils in Korea. Following is the summary of the paper. 1. Anthro aquic, Aquic Udipsamments : The top soils of these soils are saturated with irrigated water at some time of year and have mottles of low chroma(2 or less) more than 50cm of the soil surface. (Ex. Sadu, Geumcheon series) 2. Anthroaquic Udipsamments : These sails are like Anthroaquic, Aquic Udipsamments except for the mottles of low chroma within 50cm of the soil surface. (Ex. Baegsu series) 3. Halic Psammaquents : These soils contain enough salts as distributed in the profile that they interfere with the growth of most crop plants and located on the coastal dunes. The water table fluctuates with the tides. (Ex. Nagcheon series) 4. Anthroaquic, Aquic Udifluvents : They have some mottles that have chroma of 2 or less in more than 50cm of the surface. The upper horizon is saturated with irrigated water at sometime. (Ex. Maryeong series) 5. Anthro aquic Udifluvents : These soils are saturated with irrigated water at some time of year and have mottles of low chroma(2 or less) within 50cm of the surface soils. (Ex. Haenggog series) 6. Fluventic Haplaquepts : These soils have a content of organic carbon that decreases irregularly with depth and do not have an argillic horizon in any part of the pedon. Since ground water occur on the surface or near the surface, they are dominantly gray soils in a thick mineral regolith. (Ex Baeggu, Hagseong series) 7. Fluventic Thapto-Histic Haplaquepts : These soils have a buried organic matter layer and the upper boundary is within 1m of the surface. Other properties are same as Fluventic Haplaquepts. (Ex. Gongdeog, Seotan series) 8. Fluventic Aeric Haplaquepts : These soils have a horizon that has chroma too high for Fluventic Haplaquepts. The higher chroma is thought to indicate either a shorter period of saturation of the whole soils with water or some what deeper ground water than in the Fluventic Haplaquepts. The correlation of color with soil drainage classes is imperfect. (Ex. Mangyeong, Jeonbug series) 9. Fluventic Thapto-Histic Aeric Haplaquepts : These soils are similar to Fluventic Thapto Histic Haplaquepts except for the deeper ground water. (Ex. Bongnam series) 10. Fluventic Aeric Sulfic Haplaquepts : These soils are similar to Fluventic Aeric Haplaquepts except for the yellow mottles and low pH (<4.0) in some part between 50 and 150cm of the surface. (Ex. Deunggu series) 11. Fluventic Sulfaquepts : These soils are extremely acid and toxic to most plant. Their horizons are mostly dark gray and have yellow mottles of iron sulfate with in 50cm of the soil surface. They occur mainly in coastal marshes near the mouth of rivers. (Ex. Bongrim, Haecheog series) 12. Fluventic Aeric Sulfaquepts : They have a horizon that has chroma too high for Fluventic Sulfaquepts. Other properties are same as Fluventic Sulfaquepts. (Ex. Gimhae series) 13. Anthroaquic Fluvaquentic Eutrochrepts : These soils have mottles of low chroma in more than 50cm of the surface due to irrigated water. The base saturation is 60 percent or more in some subhroizon that is between depth of 25 and 75cm below the surface. (Ex. Jangyu, Chilgog series) 14. Anthroaquic Dystric Fluventic Eutrochrepts : These soils are similar to Anthroaquic Fluvaquentic Eutrochrepts except for the low chroma within 50cm of the surface. (Ex. Weolgog, Gyeongsan series) 15. Anthroaquic Fluventic Dystrochrepts : These soils have mottles that have chroma of 2 or less within 50cm of the soil surface due to artificial irrigation. They have lower base saturation (<60 percert) in all subhorizons between depths of 25 and 75cm below the soil surface. (Ex. Gocheon, Bigog series) 16. Anthro aquic Eutrandepts : These soils are similar to Anthroaquic Dystric Fluventic Eutrochrepts except for lower bulk density in the horizon. (Ex. Daejeong series) 17. Anthroaquic Hapludalfs : These soils' have a surface that is saturated with irrigated water at some time and have chroma of 2 or less in the matrix and higher chroma of mottles within 50cm of the surface. (Ex. Hwadong, Yongsu series) 18. Anthro aquic, Aquic Hapludalfs : These soils are similar to Anthro aquic Hapludalfs except for the matrix that has chroma 2 or less and higher chroma of mottles in more than 50cm of the surface. (Ex. Geugrag, Deogpyeong se ries)

• Korean Journal of Environmental Agriculture
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• v.17 no.4
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• pp.341-345
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• 1998

Soil solutions were collected by zero-tension lysimeters at Kwangju, Kyunggi Province to estimate differences in ion concentration among species and horizons. Zero-tension lysimeters were installed in O, A, and B horizons in Larix leptolepis, Pinus koraiensis, and Quercus mongolica stands. Soil solution samples were collected from September 1996 through August 1998 and analyzed for $K^+$, $NA^+$, $NH_4^+$, $Mg^{2+}$, $Ca^{2+}$, $Al^{3+}$, $Cl^-$, $SO_4^{2-}$, $NO_3^-$, and $PO_4^{3-}$. The experimental site had high nitrogen loading from the atmosphere, and $NO_3^-$ was positively correlated with $K^+$ and $Mg^{2+}$. However, $NO_3^-$ and $NH_4^+$ showed a positive correlation only in the O horizon of Q. mongolica stand. Mg^(2+) deficit in the soil was predicted owing to the positive relationship of $Mg^{2+}$ with $NO_3^-$. Concentrations of $K^+$ and $Ca^{2+}$in soil solution were estimated higher in L. leptolepis than in other stands because of high leaching from the plant. Concentration of $Al^{3+}$ in soil solution was negatively correlated with soil solution pH. Mean soil solution pH of A and B horizons in P. koraiensis was lower than 4.7, however the $Al^{3+}$ concentration was lower than the toxic level to plants.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.655-661
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• 2016

Relationships between saturated conductivity (Ks) and separate contents were evaluated from 44 soil series of arable lands: 18 for paddy fields and 26 for upland crop fields. Saturated hydraulic conductivities of A, B, and C horizons were determined with tension infiltrometer and Guelph permeameter in situ. Sand, silt, clay, and organic matter content of each horizon were analyzed. Based on correlation analysis, sand separate had a positive relationship with Ks for both paddy (r=0.27, p=0.017) and upland fields (r=0.24. p=0.030). Clay content had a negative relationship with Ks for paddy soils (r=-0.32, p=0.005) while significant correlation between them was not found for upland crop fields (r=-0.20, p=0.07). Organic matter content showed a positive relationship with Ks only for upland crop fields (r=0.33, p=0.002). Due to low correlation coefficients between separate contents and Ks, performance of pedotransfer functions was not enough to estimate Ks. It implies that hydraulic properties of arable lands were affected by other factors rather than particle characteristics. Platy structure and plow pan were suggested to limit Ks of paddy fields. Soil compaction and diversity of parent materials were proposed to influence Ks of upland crop fields. It suggests that genetic processes and artificial managements should be included in pedotransfer functions to estimate hydraulic properties appropriately.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.359-367
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• 1998

In order to determine the nitrogen supplying capabilities (NSC) of corn fields, 47 field experiments were performed in Pennsylvania over 3 year from 1986 and NSCs were estimated by the regression analysis with chemical properties and soil attributes. Although the content of $NO_3-N$ in soil showed the best correlation with NSC ($R^2=0.518$), the standardized partial regression coefficient of $NO_3-N$ for NSC was 0.52, with some variations over the years. This value was slightly higher than those of the other properties which ranged from 0.001 to 0.351. Multiple linear regression with soil attributes for the evaluation of NSC was better than simple regression with $NO_3-N$. The coefficient of determination ($R^2$) for the evaluation of NSC was gradually increased; 0.599 with selected chemical properties, 0.698 with quantitative attributes(chemical properties and depth of Ap horizon), and 0.839 with quantitative and selected qualitative soil attributes. Consequently, in order to evaluate NSC, analysis by multiple linear regression with soil attributes was more reliable and better model than by the simple regression model.

• 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.

• Journal of Forest and Environmental Science
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• v.34 no.6
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• pp.472-480
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• 2018

This study was conducted to estimate carbon storage in Quercus mongolica stands based on stand age class, and to provide basic data on the carbon balance of broad-leaved forests of Korea. The research was conducted at the experimental forest of Kangwon National University, Hongcheon-gun County, Gangwon-do Province, Korea. Three plots were set up in each of three Q. mongolica forest stands (III, V, and VII) to estimate the amount of carbon stored in Q. mongolica aboveground vegetation, coarse woody debris (CWD), organic layer, mineral soil, and litterfall. The carbon storage of the aboveground vegetation increased with an increase in stand age, while the carbon storage ratio of stems decreased. The carbon storage of the organic layer, CWD, and litterfall did not show any significant differences among age classes. In addition, the carbon concentration and storage in the forest soils decreased with depth, and there were no differences among age classes for any soil horizon. Finally, the total carbon storage in the III, V, and VII stands of Q. mongolica were 132.2, 241.1, and $374.4Mg\;C\;ha^{-1}$, respectively. In order to predict and effectively manage forest carbon dynamics in Korea, further study on deciduous forests with other tree species in different regions will be needed.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.2
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• pp.105-118
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• 2015

This study was carried out to investigate the effects of profile disturbance with different artificial accumulation history on physico-chemical properties of soil under plastic film house. The investigations included soil profile description using soil column cylinder auger F10cm x h110cm, in situ and laboratory measurements of soil properties at five sites each at the cucumber (Site Ic ~ Vc) and grape (Site Ig ~ Vg) plastic film houses with artificial soil accumulation. The sites except sites Ic, IVc, IVg and Vg, belong to ex-paddy area. The types of accumulates around root zone included sandy loam soil for 3 sites, loam soil for 1 site, saprolite for 2 sites, and multi-layer with different accumulates for 3 sites. Especially, Site IIg has mixed plow zone (Ap horizon) with original soil and saprolite, whereas disturbed soil layers of the other sites are composed of only external accumulates. The soil depth disturbed by artificial accumulation ranged from 20 cm, for Site IIg, to whole measured depth of 110 cm, for Site IVc, Vc, and Site IVg. Elapsed time from artificially accumulation to investigation time ranged from 3 months, Site IIc, to more than 20 years, Site Vg, paddy-soil covering over well-drained upland soil during land leveling in 1980s. Disturbed top layer in all sites except Site Vg had no structure, indicating low structural stability. In situ infiltration rate had no correlation with texture or organic matter content, but highest value with highest variability in Site IIIc, the shortest elapsed time since sandy loam soil accumulation. Relatively low infiltration rate was observed in sites accumulated by saprolite with coarse texture, presumably because its low structural stability in the way of weathering process could result in relatively high compaction in agro-machine work or irrigation. In all cucumber sites, there were water-transport limited zone with very low permeable or impermeability within 50 cm under soil surface, but Site IIg, IIIg, and Vg, with relatively weak disturbance or structured soil, were the reverse. We observed the big change in texture and re-increase of organic matter content, available phosphate, and exchangeable cations between disturbed layer and original soil layer. This study, therefore, suggest that the accumulation of coarse material such as saprolite for cultivating cash crop under plastic film house might not improve soil drainage and structural stability, inversely showing weaker disturbance of original soil profile with higher drainage.