• Research in Plant Disease
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• v.28 no.2
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• pp.61-68
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• 2022

Powdery mildew and two-spotted spider mite are detrimental to strawberry plants and are controlled with traditional pesticides. To accommodate consumer demand, eco-friendly methods of pest control are required. Strawberries were cultivated (in soil and in a hydroponic system) for two years, and ultraviolet B (UV-B) irradiation was used as an alternative pest control during the harvesting season. Three varieties were grown (Seolhyang, Kingsberry, and Durihyang), and four UV-B lamp/mulch (black, green, and light reflection sheet [LRS]) combinations were used during harvesting: UV-B+black or green mulch, UV-B+black or green+LRS, no UV-B+black or green, and no UV-B+black or green+LRS. In all varieties, powdery mildew was 65% more controlled when UV-B irradiation was used. The adult two-spotted spider mite density was lowest in the UV-B lamp+black or green+LRS treatments. Therefore, UV-B irradiation during the strawberry harvesting season could effectively control powdery mildew and two-spotted spider mite with little side effect on the plants.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.2
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• pp.247-253
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• 1997

Development of soybean cultivars with great nodulation and high nitrogen fixation activity, derived mostly from mutagenesis, may decrease inputs of chemical fertilizer nitrogen into the soil-plant system. Soybean seeds (cv. Jangyupkong, Hwanggeumkong, and Geomjungkong 1) were treated with three different levels of EMS (ethyl methanesulfonate) concentration(30, 50, and 70mM). Increasing the doses of EMS resulted in decreased field emergence rate of seeds, whereas it did not increase M$_2$ mutation frequencies. This indicated that the most efficient concentration of EMS was 30mM for generating mutants. Extensive mutagenesis of Sinpaldalkong 2 with 30mM EMS was undertaken to isolate soybean mutants with greater nodulation. Approximately 8, 200 M$_2$ families were screened for greater nodulation on 5 mM nitrate after inoculation with Bradyrhizobium japonicum strain YCK213-KFCC-10728. Mutant SS-2 nodulated more than the wild type. Comparison of supernodulation between SS-2 and two nts mutants(nts 1007 and nts 1116) revealed that SS-2 showed the supernodulation character at an earlier growth stage than the two nts mutants. Further studies should be needed to characterize the difference in timing of nodulation between SS-2 and nts mutants.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.409-419
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• 2023

Acid mine drainage(AMD) treatment is classified as both passive and active treatment. During the treatment, about 5,000 tons of neutralization sludge is generated as a by-product per year in Korea. This study was conducted to evaluate the characteristics of sludge generated from physico·chemical treatment processes as an active treatment from 5 different sources (D, H, S, T, Y) and the possibility of the sludges being recycled. The sludges have a pH range of 5.86 ~ pH 7.89, and a water content range of 51% ~ 82%. Most of particle sizes were less than 25 ㎛. In analysis of inorganic elements, the concentration of Al, Fe, and Mn were between 1,189 mg/kg ~ 129,344 mg/kg, 106,132 mg/kg ~ 338,011 mg/kg, and 3,472 mg/kg ~ 11,743 mg/kg, respectively. The concentration of As and Zn in sludge-T, Cd in sludge-D, Ni in sludge-H, Zn in sludge-S, and Cd in sludge-Y exceeded the soil contamination standards of Korea. The results from 2 separate kinds of leaching test, the Korea Standard Leaching Test(KSLT) and Toxicity Characteristic Leaching Procedure(TCLP), showed that all the sludges met the Korea groundwater standards. From the XRD and SEM-EDS analysis, the peaks of calcite and quartz were found in the sludges. The sludge also had a high proportion of Fe and O, and the majority of the composition was amorphous iron hydroxide.

• Journal of the Korean GEO-environmental Society
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• v.24 no.1
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• pp.5-14
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• 2023

In this study, the load transfer characteristics of the base and skin of drilled shafts were analyzed and the load sharing ratio was calculated by performing a load transfer large-scale model test and three-dimensional numerical analysis considering the similarity of drilled shafts, which is the design target. From the linear behavior of drilled shafts shown in the large-scale model test and 3D numerical analysis results, the skin load transition curve for the design conditions of this study was proposed by Baquelin et al., and the base load transition curve was proposed by Baquelin et al. For the horizontal load transition curve, the formula proposed by Reese et al. was confirmed to be appropriate. The test value was slightly larger than the numerical analysis value for the axial load at the rock socketing, but the load sharing ratio at the rock socketing increased, on average, about 27.8% as the vertical load increased. The analysis value of the vertical settlement of the pile head under the vertical load was evaluated to be slightly smaller than the test value, and the maximum vertical settlement of the pile head in the model test and analysis maximum vertical load was 10.6 mm in the test value and 10.0 mm in the analysis value, and the maximum vertical settlement value at the base of the pile was found to be a test value of 2.0 mm and an analysis value of 1.9 mm. The horizontal displacement at the head of the column (ground surface) and the head of the pile during the horizontal load was found to agree relatively well with the test value and the analysis value. As a result of the model soil test, the horizontal load measured at the maximum horizontal displacement of 38.0 mm was evaluated to be 24,713 kN, and the horizontal load in the numerical analysis was evaluated to be 26,073 kN.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.111-122
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• 2009

Dissolution of some of geo-materials may yield the loss of the soil strength and the settlement of earth structures. The goal of this study is to monitor the several physical behaviors of soluble mixtures during dissolution. Sand-salt mixtures are used to monitor the meso to macro response including the settlements and shear waves. The mixtures of photoelastic and ice disks are used to monitor micro to meso behavior of soluble mixture including the void ratio, force chain, coordination number and horizontal force changes. In the sand-salt mixtures, shear waves are measured by using bender elements in conventional oedometer cells. In the photoelastic disk - ice disk mixtures, micro to meso response are measured by digital images and load cells. The shear wave velocity decreases at the initial stage of the dissolution, and then increases and approaches to asymptotic value. The larger dissoluble particle and the more random packing produces the severe horizontal fore change. After dissolution, the void increases and the coordination number decreases. This study demonstrates that the particle level behavior such as the changes of the force chain, void ratio, and coordination number affects the global behavior such as the change of the shear wave velocity and horizontal force of the system.

• Journal of the Korean Geotechnical Society
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• v.24 no.9
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• pp.41-48
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• 2008

The aim of this study is to present a graphical method in order to evaluate stages in shrinkage cracking. Firstly, the distribution of crack openings is established by sorting the openings of individual cracks in the soil cracking system. Secondly, it is normalized in a range of 0 to 1 to obtain the normalized crack opening distribution. Thirdly, three S-shape curve models introduced by Brooks and Corey(1964), Fredlund and Xing(1994) and van Genuchten(1980) are chosen to fit the normalized crack opening distribution using a curve fitting method. The accuracy of fitting which is described through fitting parameters by the van Genuchten equation is much higher than that by the Brooks and Corey equation and slightly higher than that by the Fredlund and Xing equation; thus the van Genuchten model is used. Finally, the stages of shrinkage cracking are graphically evaluated by drawing three separate straight lines corresponding to three linear parts of the fitted normalized crack opening distribution. The proposed method is tested with different sample thicknesses. The measured data are fitted by the selected model with the fairly high regression coefficient and small root mean square error. The results show graphically that shrinkage cracking comprises three stages; namely, primary, secondary and residual stages. Subsequently, the ranges of evaluated crack opening for each of these stages are presented.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.57-67
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• 2008

Two test methods, nonrepetitive plate loading test (NPLT) and repetitive plate loading test (RPLT) are being used to control the quality of compaction through the evaluation of the stiffness of subgrade soils in the Korea railway industry. Subgrade reaction modulus ($k_{30}$) from the NPLT and strain modulus ($E_v$) from the RPLT are the index values to check them. The methods have similar aspects, but they differ in the modulus evaluation method, the numbers of loading stage, termination procedures, etc. This paper analyses the differences of the two test methods and evaluates the relationship between subgrade reaction modulus and strain modulus. In order to develop the relationship, total 22 tests were performed including the NPLT and the RPLT at the 6 original grounds, and 5 upper or lower subgrades in Kyungbu High Speed Railway II stage construction sites. According to the soil conditions, the relationship between subgrade reaction modulus and strain modulus was proposed with corrections by considering strain states, mean confining pressures, and Poisson's ratio.

• Journal of agriculture & life science
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• v.50 no.5
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• pp.111-120
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• 2016

The objective of this study was to provide basic information for selecting the right timing and the right place of erosion control of stream on Gyeongsangnam-do. In order to achieve this objective, a total of 526 erosion control dams and 230 mountains stream conservation facilities on the constructed places and construction planned places for the erosion control were investigated on site, forest physiognomy, and hydrologic conditions. The erosion control dams and mountain stream conservation facilities were mostly constructed in the area, which has the sedimentary rock, 200-400m of altitude, a slope of 21~30°, and II of landslide hazard map. Among the forest environmental factors, it was only similar to the construction frequency in the areas that have small diameter class, III age class. Also, we investigated the hydrological environmental factors that determine the size and numbers of erosion control dam. The places constructed to the highest frequency were below 50ha in the area, 2.1~4.0km/㎢ of drainage density, longitudinal water system, 61~90mm of maximum precipitation per hour, and 201~300mm of day maximum precipitation. As the results, the sites and floodgate conditions between the constructed places and stream conservation facilities for the erosion control showed to be very similar. Therefore, these results indicate that the erosion control of the stream of the areas, which have the disruption of mountain peaks and the high erosion risk areas, should be used on both the erosion control dam and stream conservation facilities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.145-151
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• 2009

Recently, the rapid development of GIS technology has made it possible to handle a various data associated with spatially hydrological parameters with their attribute information. Therefore, there has been a shift in focus from lumped runoff models to distributed runoff models, as the latter can consider temporal and spatial variations of discharge. This research is to evaluate the feasibility of GIS based distributed model using radar rainfall which can express temporal and spatial distribution in actual dam watershed during flood runoff period. K-DRUM (K-water hydrologic & hydaulic Distributed flood RUnoff Model) which was developed to calculate flood discharge connected to radar rainfall based on long-term runoff model developed by Kyoto- University DPRI (Disaster Prevention Research Institute), and Yondam-Dam watershed ($930km^2$) was applied as study site. Distributed rainfall according to grid resolution was generated by using preprocess program of radar rainfall, from JIN radar. Also, GIS hydrological parameters were extracted from basic GIS data such as DEM, land cover and soil map, and used as input data of distributed model (K-DRUM). Results of this research can provide a base for building of real-time short-term rainfall runoff forecast system according to flash flood in near future.

• Research in Plant Disease
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• v.29 no.2
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• pp.188-192
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• 2023

Abiotic and biotic stresses have been a serious threat to crop growth and productivity in the agricultural system. In this study, four strains (HS1, H30-3, KJ40, and BC42), which have biological activities related to disease suppression or alleviation of salinity and drought stresses, were tested for broad-spectrum biocontrol activity against anthracnose caused by Colletotrichum orbiculare, a bacterial fruit blotch caused by Acidovorax citrulli, and Fusarium wilt caused by Fusarium oxysporum in cucumber plants. As a result of test, when the four strains were drenched into the soil, anthracnose in cucumber leaves significantly decrease; strain KJ40 suppressed disease incidence by A. citrulli; strain BC42 significantly reduced bacterial fruit blotch and Fusarium wilt compared to control. Therefore, strain KJ40 could be a biocontrol candidate for controlling anthracnose through induced systemic resistance and the disease caused by A. citrulli as well as alleviating drought stress; strain BC42 has broad-spectrum biocontrol activity against anthracnose, Fusarium wilt, and bacterial fruit blotch.