• Journal of the Korean Society for Railway
• /
• v.19 no.2
• /
• pp.204-212
• /
• 2016

The soils used as trackbed in Korea are selected using USCS utilizing basic soil properties such as Grain Size Distribution(GSD), % passing of #200 sieve ($P_{200}$), % passing of #4 sieve ($P_4$), Coefficient of uniformity ($C_u$), and Coefficient of curvature ($C_c$). Degree of compaction of the soils adapted in the code by KR should be evaluated by maximum dry density (${\gamma}_{d-max}$) and deformation modulus $E_{v2}$. The most important influencing factor that is critical to stability and deformation of the compacted soils used as trackbed is stiffness. Thus, it is necessary to construct a correlation between the modulus and the basic soil properties of trackbed soil in order to redefine a new soil classification system adaptable only to railway construction. To construct the relationship, basic soil test data is collected as a database, including GSD, maximum dry unit weight (${\gamma}_{d-max}$), OMC, $P_{200}$, $P_4$, $C_u$, $C_c$, etc.; deformation modulus $E_{v2}$ and $E_{vd}$ are obtained independently by performing a Repeated Plated Bearing Test (RPBT) and Light Weight Deflectometer Test (LWDT) for ten different railway construction sites. A linear regression analysis is performed using SPSS to obtain the relationship between the basic soil properties and the deformation modulus $E_{v2}$ and $E_v$. Based on the constructed relationship and the various obtained mechanical test data, a new soil classification system will be proposed later as a guideline for the design and construction of trackbed foundation in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.68 no.3
• /
• pp.207-215
• /
• 2023

This study was compared the soil environment and growth and yield of onion (Allium cepa L.) treated with non-mulching (NM) and mulching polyethylene film (PEF) and two biodegradable films (BFI and BFII) commonly used in farmhouses. Visual observation confirmed the degradation of BFI and BFII films after 150 days after tansplanting (DAT). BFII increased light penetration into the films and reduced the weight maintenace after 180 DAT, with a high decompostion at 30 days after soil tilling. Soil moisture contents much fluctuated between -14 kP and - 0 kPa in NM plots, increasing the minimum soil temperature of BFI plots. Mulching treatments decreased soil organic matter contents but did not subtantially increase soil mineral nutrients, soil bulk density, and number of bacteria compared to those of NM plots. Onion root growth was increased by PEF and BFI treatments at an early growth stage, 60 DAT, with the most remarkable stem extension observed for PEF and BFI treatments after 150 DAT. PEF and BFI treatments increased the bulb's diameter, length, weight, and lodging at 180 DAT. BFI treatments exhibited a high portion of the "very large" category producing with 55.3 tons ha^-1 based on the classification into bulb size, followed by PE (49.3 tons), NM (9.4 tons), and BFII treatments (2.7 tons) at 230 DAT.

• Journal of the Korean Geosynthetics Society
• /
• v.10 no.3
• /
• pp.33-41
• /
• 2011

In this study, it conducted a compaction quality control test in 29 domestic construction sites and investigated the relationship between classical method (Cyclic Plate bearing test) and LFWD test with subgrade materials which consist in sandy soil and gravelly soil. According to the test results, the most of soil types were mostly satisfied with specification criterion and gravelly soils were easily satisfied with values over 3 times greater than specification criterion. In term of the correlation relation of soil modulus with the two compaction quality control test methods, it is shown that the sandy soil types were a good correlation, while gravelly soil types with a high stiffness materials were indicated less correlation. After the compensation for stress condition, a linear regression for elastic modulus were higher correlation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.4
• /
• pp.1373-1380
• /
• 2010

The plate loading test(PLT) and the field density test are mainly used on the construction of embankments to control the compaction of a limited layer thickness. These two test methods are very time consuming and inefficient, but they are still commonly used as the methods of quality control for soil compaction. In the last 3 decades, many devices such as geogauge, light falling weight deflectometer(LFWD) and dynamic cone penetrometer(DCP) etc., have been introduced into the engineering market with the objective of acquiring in situ stiffness properties of the compacted soil layers. Recently, a new type of sensor, called compactometer, which in mounted on the drum of a roller and measures impact forces continuously with GPS, called as Continuous Compaction Control(CCC), has come into use in many countries such as America, Germany, Japan and so on. The main objective of this paper is to assess the potential use of these new devices as quality control and assurance devices for compacted soil layers. Based on this study, compactometer and the LFWD results werestrongly correlated with the result obtained from the PLT and the field density test.

• The Korean Journal of Ecology
• /
• v.26 no.5
• /
• pp.247-250
• /
• 2003

The investigation of ecological characteristics of Lycoris radiata was carried out in flooding (site I), half flooding (site II) and dry stands (site III). Seasonal change of air temperature showed similar patterns and that of light intensity showed quite difference among three L. radiata stands. Seasonal change of soil water content showed a great difference among three L. radiata stands. The study area was dominated by Pinus densiflora, P. thunbergii and L. radiata communities. The number of bulb in 1. radiata increased in September with bulb formation and decreased in January. Bulb weight in L. radiata was different from each site. The numbers of blossom were 23, 13 and 9, respectively in site I, II and III. The length of wreath were 17.0, 13.0 and 11.0cm, respectively, the length of stamen were 7.0, 6.4 and 6.5 cm, respectively and the length of stalk were 60.0, 45.0 and 42.0 cm, respectively in site I, II and III. The leaf of L. radiata developed rapidly in site I with sufficient water supply and lower light intensity, the number and the length of rootlets increased considerably in site III with insufficient water supply and higher light intensity, and the ecological characteristics in site II was intermediate between site I and site III. There was no great difference between the numbers of rootlets in site I and site II, which were due to sufficient water supply in two stands.

• Korean Journal of Medicinal Crop Science
• /
• v.8 no.4
• /
• pp.327-333
• /
• 2000

This study was carried out to obtain the basic information for effective conservation and cultivation of Atractylodes japonica Koidz. The soil texture was sandy loam with low pH and high organic matter content compared to general cultivative land. Aerial part growth such as plant height, number of leaf, leaf length and leaf width was the highest in Tongyong indigenous species, but fresh rhizome weight was the highest in Pyongchang. Frequency of light penetration rate was high at $60{\sim}80%$ of full sun-light, but growth was better in high light penetration rate. The correlation between growth characteristics and habitat environment were investigated in 59 districts. Correation among growth characteristics in habitat, fresh rhizome weight was significant with plant height, number of leaf and stem diameter.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.2 no.4
• /
• pp.183-189
• /
• 2000

This study was carried out to analyze ecophysiological responses for seedling of Quercus serrata, Quercus mongolica and Quercus variabilis that are the typical species of deciduous broadleaved forests in Korea. And executed experiments in the climatic control room to provide necessary information to ecological forest management and methods of natural regeneration through the analysis of seedling responses. The details of experimental analysis were growth processes of 4 months after seeding that vary with the condition of three light intensity[relative light intensity(RLI) 8%, 20%, 52%] and three soil moisture[water suction(WS) Ψ=100 hPa, Ψ=280 hPa, Ψ=330 hPa] gradient, growth factors after harvesting and the nutrition condition of leaves. The results of this study are followings: 1) Early growth was prosperous after germination for the species which have more weight of acorn. 2) The formation of lammas shoot was favourable with Q. variabilis and Q. mongolica. And the rate of the occurrence was the highest in the RLI 20%, and it was remarkably reduced in the RLI 8%. 3) As the height growth of seedling of all 3 species were greater in the RLI 20% and 8% than that of the RLI 52%, they showed strong shade tolerance. 4) The increase of light intensity promoted the diameter at root collar growth, and development of main and lateral roots with all 3 species. 5) It showed that the increase of light intensity in the experimental radiation condition raised special leaf area weight(mg/cm$^2$) and leaf area productivity(mg/cm$^2$). Consequently, these resulted in the increase of leaf thickness and total dry biomass per the unit area of leaf. 6) As the increase of light intensity, the minerals contents of leaves such as N, P and K were lowered, and the increase of soil moisture resulted in the increase of P, K, Ca and Mg.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.52-52
• /
• 2022

Recently, PE (polyethylene) film has been used increasingly in com cultivation. However, PE films often cause soil and environment contamination. In order to reduce this problem, many researches have been carrying out studies on biodegradable films (BF) that are easily decomposed by soil microorganisms. Therefore, this study was conducted to determine which BF is optimal for growth and yield of com crops while also having the highest rates of film decomposition. BFs Farmsbio (Farm Hannong), Heulgro Film (Sejin Bio), Vonto Film (Eco-Hansung) as well as a selected PE film were used in this study. For the control, we used crops grown without any kind of mulching. Experimental fields were fertilized according to conventional cultivation methods, tilled, and then covered by either BF or PE. After 1 week, com (cv. MIBECK2ho) at the 3-leaf stage (16 days after seeding) was transplanted. Plant height was measured at 18 and 32 days after transplanting and heading stages. Yield components and yield were also measured at harvest. In addition, pH, EC, and decomposition and light transmittance levels of films were investigated during the experimental period. Daily average temperature, relative humidity and organic matter in soils were also measured during the experimental period. There was no significant difference in plant height, heading date, and silking between crops with BFs and PE, but the crops grown with BFs and PE films reached higher growth parameters in a shorter amount of time than the crops in the non-mulching control. Additionally, there were no significant differences in yield components such as length of ears, ear width, ear weight, and yield in crops that were grown using films or crops in the control plot. Light transmittance and decomposition levels of films generally increased with time after transplanting, and was highest in the Heulgro film than other BFs. Soil pH and organic matter in crops using BFs and PE films were significantly higher than in the control plot at 99 and 113 days after transplanting. In general, the EC contents in the control plot was lower than in crops using BFs and PE films. The average daily moisture in soil was higher when BFs and PE films were used than in the control plot. However, the daily average soil temperature was higher in crops using BFs and PE films than in the control plots at the beginning of the experimental period, but there was no consistent difference in soil temperature towards the later part of the experimental period. Therefore, the BFs used in this study were shown to be helpful without causing negative impacts on the growth and yield of com.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.8 no.4
• /
• pp.23-31
• /
• 2005

Green spaces in cities were insufficient and decreased as artificial structures increase. Accordingly, greening rooftop space contributed to urban ecosystems as green space. Especially, since 2002 Seoul supported rooftop greening and introduced 'Ecology-area rates'. Thus rooftop greening had the potentiality of extension. This prepared the extensive rooftop greenings within planting-base for extensive management rooftop greening system to be easily popularized. The extensive rooftop greening conducted from 1997-2005 reported that soil depth was 8cm and soil mixtures were 5 types. And plant were Crysanthemum zawaskii var. latilobum, Aster hayatae, Crysanthemum zawaskii herb. ssp. coreanum, Sedum sarmentosum, Sedum rotundifolium, Sedum oryzifolium, Sedum takemensis, Sedum middendorffianum, Sedum telerium var. purpureum, Sedum spectabile, Carypteris incana, Dianthus superbus, Hosta minor. As a result, for nine years after the modular type rooftop greening established, survival plants were Sedum takemensis, Sedum sarmentosum, Sedum spectabile, Sedum middendorffianum, Carypteris incana, Crysanthemum zawaskii var. latilobum, Sedum telerium var. purpureum, Sedum rotundifolium, Dianthus superbus. Also effect of greening was possibled soil depth 8cm. And growth of plants from 1997 to 2005 were fine on two soil mixtures of 'perlite+peatmoss+vermicompost+moisturizer' and 'perlite+moisturizer+bark(mulching)'. Invasive plants are Ixeris dentata Nakai, Ixeris chinensis var. strigosa, Youngia sonchifolia, Eragrostis ferruginea, Aster pilosus Willd., Ixeris japonica Nakai, Valpia myuros, and Setaria viridis. In conclusion, selection of suitable native plants was possible extensive management rooftop greening with effect of continuous greening. The extensive rooftop greening were lightweight and simple preparation without management and can popularize readily.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.154-154
• /
• 2019

Characterization of reliable field-scale root-zone soil moisture (RZSM) variability contribute to effective hydro-meterological monitoring. Although a promising cosmic-ray neutron probe (CRNP) holds the pontential for field-scale RZSM measurement, it is often restricted at deeper depths due to the non-unique sensitivity of CRNP-measured fast neutron signal to other hydrogen pools. In this study, a merging framework relied on coupling cosmic-ray soil moisture with a representative additional RZSM, was introduced to scale shallower CRNP effective depth to represent root-zone layer. We tested our proposed framework over a densely vegetated region in South Korea covering a network of one CRNP and nine in-situ point measurements. In particular, cosmic-ray soil moisture and ancillary RZSM retrieved from the most time stable location were considered as input datasets; whereas the remaining point locations were used to generate a reference RZSM product. The errors between these two input datasets and the reference were forecasted by a linear autoregressive model. A linear combination of forecasts was then employed to compute a suitable weight for merging two input products from the predicted errors. The performance of merging framework was evaluated against reference RZSM in comparison to the two original products and a commonly used exponential filter technique. The results of this study showed that merging framework outperformed other products, demonstrating its robustness in improving field-scale RZSM. Moreover, a strong relationship between the quality of input data and the performance merging framework in light of CRNP effective depth variation has been also underlined via the merging framework.