• Korean Journal of Soil Science and Fertilizer
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• v.42 no.1
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• pp.46-52
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• 2009

Deposition of atmospheric N that is depleted in $^{15}N$ has shown to decrease N isotope ratio ($^{15}N/^{14}N$,expressed as ${\delta}^{15}N$) of forest samples such as tree rings, foliage, and total soil-N. However, its effect on ${\delta}^{15}N$ of mineral soil-N which is biologically active N pool has never been tested. In this study, ${\delta}^{15}N$ of mineral N($NH{_4}^+$ and $NO_3{^-}$) in forest soils from organic and two depths of mineral soil layers (0 to 20 cm and 20 to 40cm depth) of Pinus densiflora stands located at two distinct areas (rural and industrial areas) in southern Korea was analyzed to investigate if there is any difference in ${\delta}^{15}N$ of mineral N between these areas. We also evaluated potential N loss of the study sites using ${\delta}^{15}N$ of mineral N. Across the soil layers, the ${\delta}^{15}N$ of $NH{_4}^+$ ranged from +8.9 to +24.8‰ in the rural area and from +4.4 to +13.8‰ in the industrial area. Soils from organic layer (+4.4‰) and mineral layer between 0 and 20 cm (+13.8‰) of industrial area showed significantly lower ${\delta}^{15}N$ of $NH{_4}^+$ than those of rural area (+8.9 and +24.3‰, respectively), probably indicating the greater contribution of $^{15}N$-depleted $NH{_4}^+$ from atmospheric deposition to forest in the industrial area than in the rural area. Meanwhile, ${\delta}^{15}N$ of $NO_3{^-}$ was not different between the rural and industrial areas, probably because ${\delta}^{15}N$ of $NO_3{^-}$ is more likely to be altered by the N loss that causes $^{15}N$ enrichment of the remaining soil N pool. Compared with the ${\delta}^{15}N$ of soil mineral N reported by other studies (from -10.9 to +15.6‰ for $NH{_4}^+$ and -14.8 to +5.6‰ for $NO_3{^-}$), the ${\delta}^{15}N$ observed in our study was substantially high, suggesting that the study sites are more subject to the N loss. It was concluded that $NH{_4}^+$ rather than $NO_3{^-}$ can conserve the ${\delta}^{15}N$ signature of atmospheric N deposition in forest ecosystems.

• Korean Journal of Soil Science and Fertilizer
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• v.5 no.2
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• pp.1-38
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• 1972

This study, designed to establish a classification system of paddy soils and suitability groups on productivity and management of paddy land based on soil characteristics, has been made for the paddy soils on the Gimje-Mangyeong plains. The morphological, physical and chemical properties of the 15 paddy soil series found on these plains are briefly as follows: Ten soil series (Baeggu, Bongnam, Buyong, Gimje, Gongdeog, Honam, Jeonbug, Jisan, Mangyeong and Suam) have a B horizon (cambic B), two soil series (Geugrag and Hwadong) have a Bt horizon (argillic B), and three soil series (Gwanghwal, Hwagye and Sindab) have no B or Bt horizons. Uniquely, both the Bongnam and Gongdeog series contain a muck layer in the lower part of subsoil. Four soil series (Baeggu, Gongdeog, Gwanghwal and Sindab) generally are bluish gray and dark gray, and eight soil series (Bongnam, Buyong, Gimje, Honam, Jeonbug, Jisan, Mangyeong and Suam) are either gray or grayish brown. Three soil series (Geugrag, Hwadong and Hwagye), however, are partially gleyed in the surface and subsurface, but have a yellowish brown to brown subsoil or substrata. Seven soil series (Bongnam, Buyong, Geugrag, Gimje, Gongdeog, Honam and Hwadong) are of fine clayey texture, three soil series (Baeggu, Jeonbug and Jisan) belong to fine loamy and fine silty, three soil series (Gwanghwal, Mangyeong and Suam) to coarse loamy and coarse silty, and two soil series (Hwagye and Sindab) to sandy and sandy skeletal texture classes. The carbon content of the surface soil ranges from 0.29 to 2.18 percent, mostly 1.0 to 2.0 percent. The total nitrogen content of the surface soil ranges from 0.03 to 0.25 percent, showing a tendency to decrease irregularly with depth. The C/N ratio in the surface soil ranges from 4.6 to 15.5, dominantly from 8 to 10. The C/N ratio in the subsoil and substrata, however, has a wide range from 3.0 to 20.25. The soil reaction ranges from 4.5 to 8.0. All soil series except the Gwanghwal and Mangyeong series belong to the acid reaction class. The cation exchange cpacity in the surface soil ranges from 5 to 13 milliequivalents per 100 grams of soil, and in all the subsoil and substrata except those of a sandy texture, from 10 to 20 milliequivalents per 100 grams of soil. The base saturation of the soil series except Baeggu and Gongdeog is more than 60 percent. The active iron content of the surface soil ranges from 0.45 to 1.81 ppm, easily-reduceable manganese from 15 to 148 ppm, and available silica from 36 to 366 ppm. The iron and manganese are generally accumulated in a similar position (10 to 70cm. depth), and silica occurs in the same horizon with that of iron and manganese, or in the deeper horizons in the soil profile. The properties of each soil series extending from the sea shore towards the continental plains change with distance and they are related with distance (x) as follows: y(surface soil, clay content) = $$-0.2491x^2+6.0388x-1.1251$$ y(subsoil or subsurface soil, clay content) = $$-0.31646x^2+7.84818x-2.50008$$ y(surface soil, organic carbon content) = $$-0.0089x^2+0.2192x+0.1366$$ y(subsoil or subsurface soil, pH) = $$-0.0178x^2-0.04534x+8.3531$$ Soil profile development, soil color, depositional and organic layers, soil texture and soil reaction etc. are thought to be the major items that should be considered in a paddy soil classification. It was found that most of the soils belonging to the moderately well, somewhat poorly and poorly drained fine and medium textured soils and moderately deep fine textured soils over coarse materials, produce higher paddy yields in excess of 3,750 kg/ha. and most of the soils belonging to the coarse textured soils, well drained fine textured soils, moderately deep medium textured soils over coarse materials and saline soils, produce yields less than 3,750kg/ha. Soil texture of the profile, available soil depth, salinity and gleying of the surface and subsurface soils etc. seem to be the major factors determining rice yields, and these factors are considered when establishing suitability groups for paddy land. The great group, group, subgroup, family and series are proposed for the classification categories of paddy soils. The soil series is the basic category of the classification. The argillic horizon (Bt horizon) and cambic horizon (B horizon) are proposed as two diagnostic horizons of great group level for the determination of the morphological properties of soils in the classification. The specific soil characteristics considered in the group and subgroup levels are soil color of the profile (bluish gray, gray or yellowish brown), salinity (salic), depositonal (fluvic) and muck layers (mucky), and gleying of surface and subsurface soils (gleyic). The family levels are classified on the basis of soil reaction, soil texture and gravel content of the profile. The definitions are given on each classification category, diagnostic horizons and specific soil characteristics respectively. The soils on these plains are classified in eight subgroups and examined under the existing classification system. Further, the suitability group, can be divided into two major categories, suitability class and subclass. The soils within a suitability class are similar in potential productivity and limitation on use and management. Class 1 through 4 are distinguished from each other by combination of soil characteristics. Subclasses are divided from classes that have the same kind of dominant limitations such as slope(e), wettness(w), sandy(s), gravels(g), salinity(t) and non-gleying of the surface and subsurface soils(n). The above suitability classes and subclasses are examined, and the definitions are given. Seven subclasses are found on these plains for paddy soils. The classification and suitability group of 15 paddy soil series on the Gimje-Mangyeong plains may now be tabulated as follows.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.157-165
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• 1986

This experiment was conducted to find out the some physiological characteristics and nitrogen fixation activities under free-living conditions of indigenous rhizobia isolated from soybean-cultivated (30 fields) and un-cultivated (30 fields) soil. The results were summerized as follows: 1. In free-living condition, only 12.8% and 6.4% of the indigenous rhizobia isolated from soybean cultivated (133 strains) and un-cultivated (125 strains) soils were nitrogenase positive as more than 4 n mole $C_2H_4$ per tube per hour by acetylene reduction assay. 2. The acid-producing rhizobia on litmus milk test was observed to be 20% of the total 160 strains isolated from soybean cultivated soil but about 34% of 166 strains isolated from un-cultivated soil. And the serum zone positive strains were higher in the soybean un-cultivated soil than cultivated soil. 3. The population ratio of fast-to slow-growing indigenous rhizobia based on growth pattern of AMA medium was 35.6% to 64.4% of the total 346 strains. 4. The population of indigenous Rhizobium japonicum counted by MPN method was ranged from $9.2{\times}10^2$ cells per gram of soil in soybean un-cultivated soil to $2.3{\times}10^4$ cells per gram of soil soybean cultivated soil. The number of indigenous R. japonicum in 0-10cm depth of surface layer was higher than low layer.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.2
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• pp.103-110
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• 1993

This study was made to evaluate the chemical properties of 481 farmers' orchard fields in An-Seong area. And the reasonable ferilizer rates were recommended utilizing the result of soil analysis. The results are summarized as follows : 1. As the soil fertility status of collected soil samples were evaluated on the basis of temporary optimal range for each soil chemical properties, 12.7 to 49.6% of the total 481 farmers' fields were range for soil improvement. 2. The contents of chemical component have a tendancy to decrease with depth gradually from surface to subsoil. 3. According to the relationship between the contents of soil component in subsoil and those in surface soil, the fertility condition of subsoil could be estimated on the basis of analysis data of surface soil. 4. The multiple regression equation for pear yield prediction to the organic matter and exchangable calcium contents in the soil were obtained. 5. Referring the average value, distribution ratio compared to the optimum level for each soil chemical properties and standard fertilizer rate, the soil fertility status could be categorized as "High" "Medium" and "Low". For each category, the recommended amounts for NPK and organic matter application were established. 6. The recommended rates through soul fertility diagnosis were less than farmer's dosage in the range 7.1~7.7 kg/10a for N, 0.8~11.5 kg/10a for $P_2O_5$, 7.1~19.9 kg/10a for $K_2O$ and 90~116 kg/10a for lime.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.245-253
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• 2009

The importance of chloride ions in the corrosion of steel in concrete has led to the concept for chloride threshold level (CTL). The CTL can be defined as the content of chlorides at the steel depth that is necessary to sustain local passive film breakdown and hence initiate the corrosion process. Despite the importance of the CTL, due to the uncertainty determining the actual limits in various environments for chloride-induced corrosion, conservative values such as 0.4% by weight of cement or 1.2 kg in 1 $m^3$ concrete have been used in predicting the corrosion-free service life of reinforced concrete structures. The paper studies the CTL for blended cement concrete by comparing the resistance of cementitious binder to the onset of chloride-induced corrosion of steel. Mortar specimens were cast with centrally located steel rebar of 10 mm in diameter using cementitious mortars with ordinary Portland cement (OPC) and mixed mortars replaced with 30% pulverized fuel ash (PFA), 60% ground granulated blast furnace slag (GGBS) and 10% silica fume (SF), respectively, at 0.4 of a free W/B ratio. Chlorides were admixed in mixing water ranging 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 2.0, 2.5 and 3.0% by weight of binder(Based on $C1^-$). Specimens were curd 28 days at the room temperature, wrapped in polyethylene film to avoid leaching out of chloride and hydroxyl ions. Then the corrosion rate was measured using the polarization resistance method and the order of CTL for binder was determined. Thus, CTL of OPC, 60%GGBS, 30%PFA and 10%SF were determined by 1.6%, 0.45%, 0.8% and 2.15%, respectively.

• Korean Journal of Environment and Ecology
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• v.27 no.2
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• pp.241-252
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• 2013

This study investigated plant community structure of Dongbaekdongsan(Mt.) in Jeju-do to identify character as evergreen broad-leaved forest. 20 plots(size is $20m{\times}20m$) were set up and plant communities were divided into 5 communities of Quercus glauca-Castanopsis cuspidata var. sievoldii-Ilex integra(Camellia japonica), Quercus glauca-Castanopsis cuspidata var. sievoldii-Camellia japonica, Quercus glauca-Camellia japonica, Quercus glauca-Camellia japonica-Pinus thunbergii and Pinus thunbergii-Quercus glauca by using TWINSPAN, DCA ordination, mean importance value and environmental condition. Area of Evergreen broad-leaved forest with stonny ground is covered with Quercus glauca and Castanopsis cuspidata var. sievoldii in canopy layer and Camellia japonica in the subordinate layer. Area of remaining soil's depth is covered with Pinus thunbergii. It has been alleged that Pinus thunbergii planted by human when Dongbaekdongsan(Mt.) is not selected local monuments. All of communities is predicted success to community of Quercus glauca-Camellia japonica. Shannon's diversity ranged from 1.0268 to 1.0717 in area of Evergreen broad-leaved forest and 1.2102 in area of Pinus thunbergii. 10 species of broad-leaved tree's constancy ratio is over the 80%. In future, Castanopsis cuspidata var. sievoldii and Cinnamomum japonicum can cover canopy layer, but it has low importance value. Specially high aged Camellia japonica is appeared everywhere. It has been alleged that it was touched by divinity since past. Dongbaekdongsan(Mt.) has different plant structure with another evergreen broad-leaved forest. It is hard that knowing its successional sere because it was damaged when it isn't degignate local monument. Accordingly continuous monitoring was required, successional direction and community's character is identified after forest become steady.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.137-142
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• 1998

Assessment of N release pattern from hairy vetch (Vicia villosa Roth) residue is an important step for the efficient use of the residue as a green manure and the specific management strategy development. Objective of this research was to determine the changes of chemical composition, especially in light of the N release, when the residues of hairy vetch were applied in the soil. hairy vetch was harvested at different growth stages (April 23, May 9, and May 28) and the residues were encapsulated in the nylon mesh (1 mm) bag. The bags were placed on the surface of no-tillage plots and buried at 15cm in depth in conventional tillage plots of the corn field in early June. The bags were removed for measurements of dry matter and N content at 1, 2, 3. 5, 8 and 12 weeks after placement. Dry matter and N content of hairy vetch were higher when harvested closer to maturity, as also found in C/N ratio, cellulose and hemicellulose contents. The rate of N releases from hairy vetch residue under conventional tillage condition was greater than that under no-tillage condition. Percentages of N remaining in residue over the initial N contents under conventional tillage condition were in average 40, 23, and 15% for 1, 2, and 3 weeks after placement of mesh bag, respectively, compared with respective values of 71, 31, and 21% under no-tillage condition. The rate of N release was slower as the harvest time was closer to maturity of hairy vetch under both tillage conditions. Most of N in residue was released within 3 and 5 weeks, under conventional and no-tillage conditions, respectively. Results indicated that amounts of N released from hairy vetch residue were more closely related to the variability of N contents in residue due to the harvest time than changes of chemical composition of plant or soil management.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.2
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• pp.1-11
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• 2015

This study sheds light on a pond design process which is a core facility of Hwaseol-dang in Muan, the Jeonnam. The plasticity of the pond was analyzed and interpreted for the design process using methods such as "literature search, interview, site visits, aerial pictures, aerial photographing, drawing figures of configuration plane via measurements, internet search, etc.", to trace the developing process of the design and the implications therein. The study results being centered on the developing process of the pond design are summarized herein below. The position of the Hwaseol-dang, being formed on a low hill having low competence as a place for a pavilion, draws more attention regarding its implications from the aspect of inner design. The pond Hwaseol-dang is in a rectangular shape of 1 : 1.2 ratio, in which the depth is a bit higher on the pond edge of the Hwaseol-dang thus being slanted, and Crape Myrtle, which is not known whether introduced during the formation of the pond, is cultivated on the island in the center widespread toward the southeast region. The planar design of the pond is interpreted as "rectangular pond" but it has a smooth half-moon shape where a part is excluded to remove edge. In particular, the three islands in rectangular pond, due to the narrow area, put one island and two half-moon-shaped islands in juxtaposition, and thus, although only being one island, resultantly exhibits the existence effect of proliferated three islands. This is allegedly due to the intentional formation aiming at the effect of hybrid while minimizing the overlap due to merging and adding from the aspect of constituting a design. Furthermore, the pond Hwaseol-dang is extended northwest along with Hwaseol-dang, and also the island in the center is thought to additionally have one or two, but the widespread phenomenon of the island in the center appears to consider the effect of "sit view on the floor of the pavilion of Hwaseol-dang". Considering that even a few examples of ponds having the three islands among the private house gardens in the nation are all curved ponds, the characteristics of the rectangular Hwaseol-dang pond establishing the garden effect of the three islands by modifying the one island in rectangular pond is highly notable. Considering that the three islands of "Yeongju, Bangjang, and Bongrae" is the original shape of the pond garden gestating Taoist ideology, as a symbolic design of a pond, it is regarded as the characteristics of the pond shape in Jeonnam area, and the so-called three treasures "Hwaseol-dang, Camellia, and oddly shaped stones, etc." are concentrated as the symbolism of Hwaseol-dang pond.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.1
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• pp.41-53
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• 1997

Geochemical data of soil and water samples were presented in order to assess the environmental impart for drinking water sites. Microscopic observation of rock samples and physical and chemical analysis of soil and water samples were undertaken. The geology of study areas are classified into three groups such as granitic rocks, meta-sedimentary rocks and sedimentary rocks. Enrichment of heavy metals derived from those rocks is not found in this study areas. Soils were analyzed for Cu, Pb, Zn, Cd and Cr using AAS extracted by HNO$_3$+HClO$_4$ and 0.1 N HCl. Heavy metal concentrations in soils are within the range of those in uncontaminated soils. In comparison of metal contents extracted by 0.1 N HCl and HNO$_3$+HC1O$_4$, less than 10% of the heavy metals are present in the exchangeable fraction. In particular, an pollution index has been proposed to assess the degree of soil contamination. Pollution index in soils are between 0.03 and 0.47 therefore, soils are not polluted with heavy metals. Deep groundwaters within granitic rocks have been evolved into Na$\^$＋/-HCO$_3$$\^$-/ type, whereas other deep groundwaters evolved into Ca$\^$2＋/-HCO$_3$$\^$-/ type. The predominance of Na$\^$＋/ over Ca$\^$2＋/ in deep groundwaters within granitic rocks is a result of dissolution of plagioclase, but for sedimentary and meta-sedimentary rocks, dissolution of calcite is a dominant factor for their hydrogeochemistry. The pH, conductivity and contents of the most dissolved ions in the water increase with depth. Shallow groundwaters, however, are highly susceptible to pollution owing to agricultural activities, considering the fact that high contents of nitrate, chloride and potassium, and high K/Na ratio are observed in some shallow groundwaters. In a thermodynamic approach, most natural water samples are plotted within the stability fields of kaolinite and smectite. Therefore, microcline and other feldspars will alter to form clay minerals, such as kaolinite and smectite. From the modelling for water-rock interactions based on mass balance equation, models accord well with behavior of the ions and results of thermodynamic studies are derived.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.145-159
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• 2004

The conventional method for assessment of liquefaction potential proposed by Seed and Idriss has been widely used in most countries because of simplicity of tests. Even though various data such as stress, strain, stress path, and excess pore water pressure can be obtained from the dynamic test, especially, two simple experimental data such as the maximum deviatoric stress and the number of cycles at liquefaction have been used in the conventional assessment. In this study, a new detailed assessment for liquefaction potential to reflect both characteristics of real earthquake motion and dynamic soil resistance is proposed and verified. In the assessment, the safety factor of the liquefaction potential at a given depth of a site can be obtained by the ratio of a resistible cumulative plastic shear strain determined through the performance of the conventional cyclic test and a driving cumulative plastic shear strain calculated from the shear strain time history through the ground response analysis. The last point to cumulate the driving plastic shear strain to initiate soil liquefaction is important for this assessment. From the result of cyclic triaxial test using real earthquake motions, it was concluded that liquefaction under the impact-type earthquake loads would initiate as soon as a peak loading signal was reached. The driving cumulative plastic shear strain, therefore, can be determined by adding all plastic shear strains obtained from the ground response analysis up to the peak point. Through the verification of the proposed assessment, it can be concluded that the proposed assessment for liquefaction potential can be a progressive method to reflect both characteristics of the unique soil resistance and earthquake parameters such as peak earthquake signal, significant duration time, earthquake loading type, and magnitude.