• Biomolecules & Therapeutics
• /
• v.14 no.4
• /
• pp.246-252
• /
• 2006

1,2-Dibromoethane(DBE) has been widely used as a soil fumigant, an additive to leaded gasoline and an industrial solvent. In this study, we have carried out in vitro genetic toxicity test of 1,2-dibromoethane and microarray analysis of differentially expressed genes in response to 1,2-dibromoethane. 1,2-Dibromoethane showed mutations in base substitution strain TA1535 both with and without exogenous metabolic activation. 1,2-Dibromoethane showed mutations in frame shift TA98 both with and without exogenous metabolic activation. 1,2-Dibromoethane showed DNA damage based on single cell gel/comet assay in L5178Y cells both with and without exogenous metabolic activation. 1,2-Dibromoethane increased micronuclei in CRO cells both with and without exogenous metabolic activation. Microarray analysis of gene expression profiles in L5178Y cells in response to 1,2-dibromoethane selected differentially expressed 241 genes that would be candidate biomarkers of genetic toxic action of 1,2-dibromoethane.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.214-214
• /
• 2015

Rainfall induced landslides is one of the most devastating natural disasters acting on mountainous areas. In Korea, landslide damage areas increase significantly from 1990s to 2000s due to the increase of both rainfall intensity and rainy days in addition with haphazard land development. This study was carried out based on the application of TRIGRS unsaturated (Transient Rainfall Infiltration and Grid-based Regional Slope stability analysis), a Fortran coded, physically based, and numerical model that can predict landslides for areas where are prone to shallow precipitation. Using TRIGRS combining with the geographic information system (GIS) framework, the landslide incident happened on 27th, July 2011 in Mt. Umyeon in Seoul was modeled. The predicted results which were raster maps showed values of the factors of safety on every pixel at different time steps show a strong agreement with to the observed actual landslide scars in both time and locations. Although some limitations of the program are still needed to be further improved, some soil data as well as landslide information are lack; TRIGRS is proved to be a powerful tool for shallow landslide susceptibility zonation especially in great areas where the input geotechnical and hydraulic data for simulation is not fully available.

• Journal of the Korea Safety Management & Science
• /
• v.18 no.4
• /
• pp.1-9
• /
• 2016

In recent years, urban areas occurred several times a sinkhole. In Korea, this limestone area where the sink hole sink holes occur based on not much was seen as a very rare phenomenon. However, the occurrence of accidents in recent Subsidence and urban areas is occurring in the limestone sinkhole may yet see another one called artificial Subsidence phenomenon. Subsidence in urban areas can have various causes, such as depression groundwater level changes due to the influence of soil, underground, etc. underground utilities by anthropogenic actions. But a lot of research on natural sinkhole by geological experts continued steadily since the past Subsidence that occurred in recent years the city has become an urgent problem to formulate a countermeasure to be very concerned about the human and material damage. In this study, the city by analyzing existing research on the causes and countermeasures of Subsidence recently released look at the announced sinkhole, published statistics and cases of Subsidence data, and overseas corresponding practices in each relevant agencies and to suggest measures for local Subsidence.

• Geomechanics and Engineering
• /
• v.16 no.6
• /
• pp.635-642
• /
• 2018

Braced excavation systems are commonly required to ensure stability in construction of basements for shopping malls, underground transportation and other habitation facilities. For excavations in deposits of soft clays or residual soils, stiff retaining wall systems such as diaphragm walls are commonly adopted to restrain the ground movements and wall deflections in order to prevent damage to surrounding buildings and utilities. The ground surface settlement behind the excavation is closely associated with the magnitude of basal heave and the wall deflections and is also greatly influenced by the possible groundwater drawdown caused by potential wall leakage, flow from beneath the wall, flow from perched water and along the wall interface or poor panel connections due to the less satisfactory quality. This paper numerically investigates the influences of excavation geometries, the system stiffness, the soil properties and the groundwater drawdown on ground surface settlement and develops a simplified maximum surface settlement Logarithm Regression model for the maximum ground surface settlement estimation. The settlements estimated by this model compare favorably with a number of published and instrumented records.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.18 no.6
• /
• pp.9-18
• /
• 2019

This study derives load characteristics and analyzes the safety of plowshares operating in dry fields. We mounted a three-blade, reversible plow on a 23.7 kW tractor and measured the plow's tractive force as well as the torque from the engine output shaft on the rear axle under various working speeds (L4, M1, M2, M3). We chose a Korean test site of Seomyeon, Chuncheon with sandy soil texture, as determined using the USDA method. We constructed the load spectrum for torque and tractive force using measured data and derived the fatigue life of the plowshare from a stress-cycle (S-N) curve of the plow material. Our results show that the M3 gear maximizes the driving shaft torque loads and, applying the tractive force load spectrum, creates a cumulative damage sum of $4.14{\times}10^{-5}$. Considering sampling time, we estimate a fatigue life of 805 hours while using the M3 gear. When using the other working speeds, however, all of the stress levels fell within the endurance limits and, therefore, our model predicts infinite plowshare lifetimes. For this analysis, we used a yield strength of 1,079 MPa for the plowshare and static safety factors, analyzed using the maximum stress, between 6.83 and 8.63 under each working speed.

• Geomechanics and Engineering
• /
• v.17 no.5
• /
• pp.421-427
• /
• 2019

Coastal erosion is becoming a significant problem in Greece, Bangladesh, and globally. For the prevention and minimization of damage from coastal erosion, combinations of various structures have been used conventionally. However, most of these methods are expensive. Therefore, creating artificial beachrock using local ureolytic bacteria and the MICP (Microbially Induced Carbonate Precipitation) method can be an alternative for coastal erosion protection, as it is a sustainable and eco-friendly biological ground improvement technique. Most research on MICP has been confined to land ureolytic bacteria and limited attention has been paid to coastal ureolytic bacteria for the measurement of urease activity. Subsequently, their various environmental effects have not been investigated. Therefore, for the successful application of MICP to coastal erosion protection, the type of bacteria, bacterial cell concentration, reaction temperature, cell culture duration, carbonate precipitation trend, pH of the media that controls the activity of the urease enzyme, etc., are evaluated. In this study, the effects of temperature, pH, and culture duration, as well as the trend in carbonate precipitation of coastal ureolytic bacteria isolated from two coastal regions in Greece and Bangladesh, were evaluated. The results showed that urease activity of coastal ureolytic bacteria species relies on some environmental parameters that are very important for successful sand solidification. In future, we aim to apply these findings towards the creation of artificial beachrock in combination with a geotextile tube for coastal erosion protection in Mediterranean countries, Bangladesh, and globally, for bio-mediated soil improvement.

• Geomechanics and Engineering
• /
• v.30 no.1
• /
• pp.27-44
• /
• 2022

Gravelly soil is a kind of special geotechnical material, which is widely used in the subgrade engineering of railway, highway and airport. Its mechanical properties are very complex, and will greatly influence the stability of subgrade engineering. To investigate the mechanical properties and failure mechanism of gravelly soils, this paper introduced and verified a new discrete element method (DEM) of gravelly soils in large scale direct shear test, which considers the actual shape and broken characteristics of gravels. Then, the stress and strain characteristics, particle interaction, particle contact force, crack development and energy conversion in gravelly soils during the shear process were analyzed using this method. Moreover, the effects of gravel content (GC) on the mechanical properties and failure characteristics were discussed. The results reveal that as GC increases, the shear stress becomes more fluctuating, the peak shear stress increases, the volumetric strain tends to dilate, the average particle contact force increases, the cumulative number of cracks increases, and the shear failure plane becomes coarser. Higher GC will change the friction angle with a trend of "stability", "increase", and "stability". Differently, it affects the cohesion with a law of "increase", "stability" and "increase".

• Journal of the Korean Society of Safety
• /
• v.37 no.6
• /
• pp.148-157
• /
• 2022

Every year, particularly during the monsoon rainy season, landslides at the Chuncheon province of South Korea cause tremendous damage to lives, properties, and infrastructures. More so, the high rainfall intensity and long rainfall days that occurred in 2020 have increased the water content in the soil, thereby increasing the chances of landslide occurrences. Besides this, the rainfall thresholds and characteristics responsible for the initiation of landslides in this region have not been properly identified. Therefore, this paper addresses the rainfall thresholds responsible for the initiation of landslides at Chuncheon from a regional perspective. Using data obtained from rainfall measurements taken from 2002 to 2011, we identify a threshold relationship between rainfall intensity and rainfall duration for the initiation of landslides. In addition, we identify the relationship between the rainfall intensity using a 3-day, 7-day, and 10-day antecedent rainfall observation. Specifically, we estimate the rainfall data at 8 sites where debris flow occurred in 2011 by kriging. Following this, the estimated data are used to construct the relationship between the intensity (I), duration (D), and frequency (F) of rainfall. The results of the intensity-duration-frequency (IDF) analysis show that landslides will occur under a rainfall frequency below a 2-year return period at two areas in Chuncheon. These results will be effectively used to design structures that can prevent the occurrence of landslides in the future.

• Journal of Environmental Science International
• /
• v.31 no.6
• /
• pp.461-470
• /
• 2022

When an agricultural soil dam collapses, the extent of inundation and the rate of diffusion vary depending on where the collapse occurs in the dam body. In this study, a dam collapse scenario was established and a two-dimensional numerical model FLO-2D was used to closely examine the inundation pattern of the downstream residential area according to the dam collapse point. The results were presented as a flood risk map showing the changes and patterns of the extent of inundation spread. The flood level and the time to reach the maximum water level vary depending on the point of collapse, and the inundation of the downstream area proceeds rapidly in the order of the midpoint, left point, and right point collapse. In the left collapse point, the submergence appeared about 0.5 hour slower than the middle point, and the right collapse point appeared about 1 hour slower than the middle point. Since the relative damage pattern is different depending on the dam collapse point, insurance and disaster countermeasures will have to be established differently.

• International Journal of Computer Science & Network Security
• /
• v.22 no.9
• /
• pp.403-413
• /
• 2022

Classification and analysis are improved factors for the realtime automation system. In the field of agriculture, the cultivation of different paddy crop depends on the atmosphere and the soil nature. We need to analyze the moisture level in the area to predict the type of paddy that can be cultivated. For this process, Ensemble Modulation Pattern system and Block Probability Neural Network based classification models are used to analyze the moisture and temperature of land area. The dataset consists of the collections of moisture and temperature at various data samples for a land. The Ensemble Modulation Pattern based feature analysis method, the extract of the moisture and temperature in various day patterns are analyzed and framed as the pattern for given dataset. Then from that, an improved neural network architecture based on the block probability analysis are used to classify the data pattern to predict the class of paddy crop according to the features of dataset. From that classification result, the measurement of data represents the type of paddy according to the weather condition and other features. This type of classification model assists where to plant the crop and also prevents the damage to crop due to the excess of water or excess of temperature. The result analysis presents the comparison result of proposed work with the other state-of-art methods of data classification.