• Journal of Korean Society of Forest Science
• /
• v.104 no.3
• /
• pp.352-359
• /
• 2015

This study was conducted to evaluate how the special protection area designations of degraded trails effect on the soil and vegetation recovery of degraded trails. The study areas were established on an opened trail and a 16-year closed trail, which was prohibited to enter after the designation as a special protection area for recovery, at Bukhansan National Park. Soil core sampling and measurements of vegetation cover were performed to compare soil and vegetation properties of the trails. Soil bulk density increased and soil water total nitrogen decreased on the opened trail, while no significant differences were found on bulk density, soil water, total nitrogen, acidity, and organic matter on the closed trail. On the opened trail, vegetation cover was seemed to be degraded, because vegetation litter cover ratio was low and barren rock cover ratio was high. On the closed trail, litter rock barren cover ratio of the closed trail was recovered, but only limited recovery was found on vegetation cover by applying environmental damage condition rating class. In conclusion, the closed trail was recovered by designation of special protection area, while difference in recovery progress of soil and vegetation was found. Therefore, designation of special protection area of degraded area should be based on scientific basis of recovery characteristics of the area. In order to improve the effectiveness of special protection area system, further specific standards for special protection area designation and management would be needed, considering ecological and social importance of target areas.

• Economic and Environmental Geology
• /
• v.54 no.4
• /
• pp.483-494
• /
• 2021

This study was carried out to investigate the feasibility of reducing clean cover soil using a flooded column test in arsenic-contaminated farmland reclamation of abandoned coal mine area that shows generally low or about worrisome level (25 mg/kg) of Korea soil environment conservation act unlike abandoned metal mine. During the monitoring period of soil solution for 4 months, chemical properties (pH, EC, ORP, Fe, Mn, Ca, and As) in each layer (clean soil cover and contaminated/stabilized soil) showed different variation. This result revealed that soil solution in stabilized or contaminated soil rarely affected that in cover soil. Whether stabilized or not, arsenic concentrations in the rice roots grown in the soil covers with the thickness of 40 cm decreased by 98% in compared with the that grown in the control soil. In case of the soil covers with 20 cm thickness on stabilized soil, it decreased by 80% and this was 22 percentage point higher than when the soil of lower layer was not stabilized. Thus, reducing clean cover soil could be possible in contaminated farmland soil reclamation if appropriate stabilization of contaminated soil is carried.

• Journal of Forest and Environmental Science
• /
• v.38 no.1
• /
• pp.21-37
• /
• 2022

The present study was carried out to evaluate the chemical properties of soil in relation to forest structure and composition at different altitudes (900-2,600 m asl) in a part of Western Himalaya. The composite soil samples were taken from three (viz. upper, middle and lower) depths. The soils of the whole study area were acidic in nature (pH=4.90-5.51). Contents of Nitrogen (N), Phosphorus (P), Potassium (K), Carbon (C) and soil organic matter (SOM) showed much fluctuation during different seasons of year. Nitrogen content showed significant positive correlations with altitude (r=0.924, p<0.05) and different community parameters like species diversity (r=0.892, p<0.01) and species richness (r=0.941, p<0.05). Phosphorus exhibited direct correlations with carbon (r=0.637) while weak negative correlations with different community parameters like species richness & diversity, total basal cover (TBC), density and canopy cover. Carbon content and hence SOM showed direct correlations with Nitrogen (r=0.821, p<0.01); Phosphorus (r=0.637, ns) and Potassium (r=0.540, ns). But no significant relationship was observed between K content and species richness (p=0.30, r=-0.504); between K content and species diversity (p=0.14, r=-0.672); between P content and species diversity (p=0.29, r=-0.513) and species richness (p=0.23, r=-0.575). Among the different soil nutrients, only N showed a significant positive correlation with altitude while all others exhibited negative (but non-significant) correlation with it. The study revealed that the chemical properties affect and are reciprocally affected by forest structure and composition and that N rich soils of higher altitudes are best for the growth and development of forests.

• East Asian mathematical journal
• /
• v.30 no.1
• /
• pp.63-67
• /
• 2014

Observing that for any P'-space X, ${\Lambda}vX$ is a P'-space if vX is a weakly Lindel$\ddot{o}$f space, (${\Lambda}vX{\times}{\Lambda}Y$, ${\Lambda}_X{\times}{\Lambda}_Y$) is the minimal basically disconnected cover of $X{\times}Y$ for a countably locally weakly Lindel$\ddot{o}$f space Y.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.7 no.2
• /
• pp.71-78
• /
• 1987

This experiment was carried out to examine the effects of sowing method and summer management on the dry matter yield, dead matter, weed development and ground cover of orchardgrass (Dactylis glomerata L.) meadow. The experiment was allocated as a split-split plot design with three replications. The main plots were sowing method of drilling and broadcasting, sub plots were drainage of experimental field, adequate and inadequate, and sub-sub plots were cutting timeof orchardgrass, cutting before rainy season started and cutting after rainy season ended. The experiment was undertaken over a period of 14 months from September, 1983 to October, 1984. The results obtained are summarized as follows: 1. There were no significant differences in dry matter yield among treatments at the first cutting, but cutting before rainy season produced significantly more forage yield ($P{\le}0.01$) than cutting after rainy season at the second and third cuts. At the third cutting, drilled orchardgrass meadow showed a significant dry matter yield ($P{\le}0.05$) than broadcast orchardgrass meadow, 2. The dead matter of orchardgrass was accumulated only at the second cutting when orchardgrass meadow cut after rainy season. Orchardgrass produced in the adequate and inadequate drainage plots consisted 20.4 and 35.9% of dead material, respectively, but no significant difference was found between two drainage treatments. 3. Drilled orchardgrass meadow produced significantly less weeds ($P{\le}0.05$) than broadcast orchardgrass meadow, but the plots cut after rainy season produced significantly more weeds ($P{\le}0.01$) than the plots cut before rainy season. 4. The percent ground cover of orchardgrass in the plots cut before rainy season was significantly higher ($P{\le}0.01$) than that in the plots cut after rainy season at the second cutting. Drilled plots showed a slight increase in the ground cover than the broadcast, but the difference was not significant. The same trend of ground cover of the meadow estimated at the second cutting was sustained after the third cutting. 5. Based on the results of the experiment, it indicates that the second cut of orchardgrass should be made before rainy season related for maintaining high yield of the meadow. Drilling as a sowing method of orchardgrass meadow could be adopted in the view point of reducing weed development.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.2
• /
• pp.185-191
• /
• 2023

To the exact cover problem that remains NP-complete to which no polynomial time algorithm is made available, this paper proposes a linear time algorithm that yields an optimal solution. The proposed algorithm makes use of the set cover problem's major feature which states that "no identical element shall be included in more than one covering set". To satisfy this criterion, the proposed algorithm initially selects a subset with the minimum cardinality and deletes those that contain the cardinality identical to that of the selected subset. This process is repeatedly performed on remaining subsets until the final solution is obtained. Provided that the solution is unattainable, it selects subsets with the maximum cardinality and repeats the same process. The proposed algorithm has not only obtained the optimal solution with ease but also proved its wide applicability on N-queens problems, hence disproving the NP-completeness of the exact cover problem.

• Asian Journal of Turfgrass Science
• /
• v.23 no.1
• /
• pp.123-132
• /
• 2009

This study was designed to investigate the effect of the late fall fertilization applied with methyl urea(MU), compound chemical fertilizer(CF), humate(HM), and organic compost fertilizer(NS) on spring greenup of creeping bentgrass at following year. The plots were treated with various snow cover periods before transforming to ski slopes from golf holes during 2007 fall to 2008 spring. The highest visual quality and greenup rate were shown on MU or HM applications at 10 days before snow cover treatment. The CF treatment which had a highest phosphorus rate was most effective with a 13 cm of root length at the reconversion date to golf hole from ski slope of the following spring. However, the application of CF followed by immediate snow cover showed the worst results on visual quality and green color caused by a leaf burning damage from the residual effect of CF. At least 10 days were required to avoid phytotoxicant from undissolved granular of CF before snow cover practise. The application of NS showed the highest result on leaf dry weight at no snow cover plot in next spring, but not on green color and visual quality. Therefore, the proper interval period of snow cover after late fall fertilization should be an important management skill on the spring greenup of creeping bentgrass on following year transforming from ski slope to golf hole.

• Korean Journal of Plant Resources
• /
• v.28 no.5
• /
• pp.641-647
• /
• 2015

This study was conducted to select native ground cover plants for sod culture in an organic apple orchard by estimating the effect of three native ground cover plants, Glechoma hederacea, Thymus magnus, and Ixeris stolonifera, on the soil coverage, time-periodic weed occurrence, fruit characteristics, and soil chemical properties. The plant height of G. hederace, T. magnus and I. stolonifera were 15.0 ㎝, 13.4 ㎝ and 7.2 ㎝, respectively. The dry weight of G. hederace, T. magnus and I. stolonifera were 463 ㎏/10a, 247 ㎏/10a, and 255 ㎏/10a, respectively. The plant height and dry weight of G. hederacea were higher than in the other species. T. magnus and I. stolonifera having relatively lower soil cover rate during their life cycle produced a lot of weeds in the orchard as compared with the control. In contrast, G. hederacea showed 100 percentage of ground cover in the first year, and maintained high percentage of ground cover in the growing season of ‘Tsugaru’ apple for another 2 years. When the soil was covered with G. hederacea in the orchard for 3 years, the amount of weed was only 114 ㎏/10a and number of weeding was also reduced about 33% compared with control as well as the other species. There were no differences in the tree growth and fruit characteristics between the native ground cover plants and the control; however, positive effects of native ground cover plants on soil chemical properties were found. In G. hederacea, available P₂O₄content in soils remarkably increased and was a significant difference among native species. In addition, cation (Ca, Mg and K) content in soils increased by 39% in Ca, 6% in Mg, and 11% in K at G. hederacea compared with control. These results suggest that G. hederacea could be advantageous in terms of reducing the amount of herbicide applied and the labor required for weed control, and controlling soil chemical properties; therefore, it is a good candidate for sod culture in an organic apple orchard.

• Journal of Korean Society of Forest Science
• /
• v.112 no.3
• /
• pp.267-279
• /
• 2023

This research assessed the feasibility of using high-resolution aerial images and deep learning algorithms for estimating the land-use and land-cover areas at the Approach 3 level, as outlined by the Intergovernmental Panel on Climate Change. The results from different sampling densities of high-resolution (51 cm) aerial images were compared with the land-cover map, provided by the Ministry of Environment, and analyzed to estimate the accuracy of the land-use and land-cover areas. Transfer learning was applied to the VGG16 architecture for the deep learning model, and sampling densities of 4 × 4 km, 2 × 4 km, 2 × 2 km, 1 × 2 km, 1 × 1 km, 500 × 500 m, and 250 × 250 m were used for estimating and evaluating the areas. The overall accuracy and kappa coefficient of the deep learning model were 91.1% and 88.8%, respectively. The F-scores, except for the pasture category, were >90% for all categories, indicating superior accuracy of the model. Chi-square tests of the sampling densities showed no significant difference in the area ratios of the land-cover map provided by the Ministry of Environment among all sampling densities except for 4 × 4 km at a significance level of p = 0.1. As the sampling density increased, the standard error and relative efficiency decreased. The relative standard error decreased to ≤15% for all land-cover categories at 1 × 1 km sampling density. These results indicated that a sampling density more detailed than 1 x 1 km is appropriate for estimating land-cover area at the local level.

• Communications of the Korean Mathematical Society
• /
• v.27 no.4
• /
• pp.665-668
• /
• 2012

For a given graph G we consider a set S(G) of all symmetric matrices A = [$a_{ij}$] whose nonzero entries are placed according to the location of the edges of the graph, i.e., for $i{\neq}j$, $a_{ij}{\neq}0$ if and only if vertex $i$ is adjacent to vertex $j$. The minimum rank mr(G) of the graph G is defined to be the smallest rank of a matrix in S(G). In general the computation of mr(G) is complicated, and so is that of the maximum multiplicity MaxMult(G) of an eigenvalue of a matrix in S(G) which is equal to $n$ - mr(G) where n is the number of vertices in G. However, for trees T, there is a recursive formula to compute MaxMult(T). In this note we show that this recursive formula for MaxMult(T) also computes the path cover number $p$(T) of the tree T. This gives an alternative proof of the interesting result, MaxMult(T) = $p$(T).