• The Journal of Engineering Geology
• /
• v.31 no.3
• /
• pp.333-342
• /
• 2021

In this study was conducted to measure the water content and dry unit weight of the ground using TDR (Time Domain Reflectometry) in order to supplement the problems of the conventional compaction management method. The Flat TDR system is a device that does not cause ground disturbance, and in order to verify the measured values, the dry density and water content were measured for samples of the ground subject at 7 sites other than Jumunjin Standard Temple. The water content section was divided into 6 sections of 3, 6, 9, 12, 15, and 18%, and the experimental results were confirmed according to the unified classification method. As a result of the indoor experiment, the water content showed an error of about 0.7% for the SP sample and about 1.3% for the SM sample. In addition, the dry unit weight confirmed an error of about 7% for the SP sample and about 5% for the SM sample. It was confirmed that stable values were derived in sandy or silty sandy ground except for clay or gravel. Through the experimental results, it was confirmed that the measured values of the flat TDR system derive similar values to the existing traditional compaction management method, and it was determined that the flat TDR equipment was suitable for construction sites that require quick constructability and economic feasibility.

• Korean Journal of Environment and Ecology
• /
• v.35 no.5
• /
• pp.503-524
• /
• 2021

A largemouth bass (Micropterus salmoides) is an ecosystem disturbance fish species at the highest rank in the aquatic ecosystem, causing a serious imbalance in freshwater ecosystems. Although various attempts have been made to eradicate and control largemouth bass, no effective measures were found. Therefore, it is necessary to find an approach to maximize the effective population reduction based on the unique characteristics of largemouth bass. This study used the transcriptome analysis to derive 182,887 unigene contigs and select 12 types of final target sequences for applying the CRISPR/Cas9 system in the genes of IZUMO1 and Zona pellucida sperm-binding protein, which are proteins involved in sperm-egg recognition. After synthesizing 12 types of sgRNA capable of recognizing each target sequence, 12 types of Cas9-sgRNA ribonucleoprotein (RNP) complexes to be used in subsequent studies were prepared. This study searched the protein-coding gene of sperm-egg through the Next Generation Sequencing (NGS) and edited genes through the CRISPR/Cas9 system to induce infertile individuals that produced reproductive cells but could not form fertilized eggs. Through such a series of processes, it successfully established a composition development process for largemouth bass. It is judged that this study contributed to securing the valuable basic data for follow-up studies to verify its effect for the management of ecological disturbances without affecting the habitat of other endemic species in the same water system with the largemouth bass.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.7
• /
• pp.930-938
• /
• 2018

Underwater noise radiated from submarines is directly related to the probability of being detected by the sonar of an enemy vessel. Therefore, minimizing the noise of a submarine is essential for improving survival outcomes. For modern submarines, as the speed and size of a submarine increase and noise reduction technology is developed, interest in flow noise around the hull has been increasing. In this study, a noise analysis technique was developed to predict flow noise generated around a submarine shape considering the free surface effect. When a submarine is operated near a free surface, turbulence-induced noise due to the turbulence of the flow and bubble noise from breaking waves arise. First, to analyze the flow around a submarine, VOF-based incompressible two-phase flow analysis was performed to derive flow field data and the shape of the free surface around the submarine. Turbulence-induced noise was analyzed by applying permeable FW-H, which is an acoustic analogy technique. Bubble noise was derived through a noise model for breaking waves based on the turbulent kinetic energy distribution results obtained from the CFD results. The analysis method developed was verified by comparison with experimental results for a submarine model measured in a Large Cavitation Tunnel (LCT).

• Journal of the Korean GEO-environmental Society
• /
• v.12 no.1
• /
• pp.51-60
• /
• 2011

Electrical resistivity is applied for understanding details about layers and obtaining basic properties of soils to various measurement devices. The objective of this study is development of TRP(Temperature-compensated Resistivity Probe), analysis about effects of temperature changes during cone penetration test, and observation of characteristics of cone penetration. In order to observation of temperature changes according to a diameter difference of resistivity cone probe, the cone which has wedge type cone tip is made to two types, 2mm and 5mm. Temperature sensor is attached at 15mm below from cone tip because of an electrical interference with elecrical resistance probe. Delectrical connector is used to prevent electric disturbance between motor type penetrating machine and electrical resistivity cone probe. Application tests are carried out in acrylic cell whose diameter is 30cm with uniform Jumunjin sand according to densification caused by blows. The test results indicate that the temperature is increased uniformly during penetration and a tendency, characteristics of cone penetration, is discovered during altering state of soils. This study suggests that the temperature effects and characteristics of penetration should be considered in penetrating tests in order to conduct an accurate ground investigation using TRP(Temperature-compensated Resistivity Probe).

• Economic and Environmental Geology
• /
• v.54 no.6
• /
• pp.615-627
• /
• 2021

The Baekildo fault, a dextral strike-slip fault developed in Baekil Island, Goheung-gun, controls the distribution of tuffaceous sandstone and lapilli tuff and shows a complex fracture system around it. In this study, we examined the spatial variation in the geometry and connectivity of the fracture system by using circular sampling and topological analysis based on a detailed fracture trace map. As a result, both intensity and connectivity of the fracture system are higher in tuffaceous sandstone than in lapilli tuff. Furthermore, the degree of the orientation dispersion, intensity, and average length of fracture sets vary depending on the along-strike variation in structural position in the tuffaceous sandstone. Notably, curved fractures abutting the fault at a high angle occur at a fault bend. Based on the detailed observation and analyses of the fracture system, we conclude as follows: (1) the high intensity of the fracture system in the tuffaceous sandstone is caused by the higher content of brittle minerals such as quartz and feldspar. (2) the connectivity of the fracture system gets higher with the increase in the diversity and average length of the fracture sets. Finally, (3) the fault bend with geometric irregularity is interpreted to concentrate and disturb the local stress leading to the curved fractures abutting the fault at a high angle. This contribution will provide important insight into various geologic and structural factors that control the development of fracture systems around faults.

• Journal of Practical Agriculture & Fisheries Research
• /
• v.23 no.1
• /
• pp.13-26
• /
• 2021

This study was conducted to identify various types of activities of payment contract for ecosystem services. As supporting services, 12 types of activities were derived: fallow, eco-friendly crop cultivation, shelter creation management, etc. As regulating services, 5 types of activities were derived: stream environment purification, creation and management of riparian vegetation, creation and management of forests for responding to climate change, etc. As cultural services, five types of activities were derived: creation and management of landscape forests, creation and management of ecological trails, managing ecosystem conservation, etc.

• Journal of agricultural medicine and community health
• /
• v.47 no.4
• /
• pp.229-241
• /
• 2022

Purpose: This study was attempted to identify the demographic characteristics, depression, and dietary quality of elderly patients with type 2 diabetes, and to identify the difference in food quality according to these variables. Methods: The subjects of the study were 216 elderly patients with type 2 diabetes over the age of 65 visiting elderly welfare centers and senior citizens' centers in G city and H districts. Data were collected from December 2020 to July 2021. The collected data were analyzed by descriptive statistics, t-test and one-way ANOVA using IBM SPSS Statistics 21 program. Results: There were significant differences in dietary quality according to the subject's gender, education level, residential area, spouse or not, family living together or not, subject of meal preparation, calorie requirement recognition or not, exercise practice for diabetes management or not, and depression. Depression and Fasting Blood Sugar management were important influencing factors on dietary quality, and Residence and Gender were also verified as influencing factors. Conclusions: The results of this study can be provided as basic data to establish a program to improve the quality of meals for diabetic elderly patients.

• Economic and Environmental Geology
• /
• v.55 no.1
• /
• pp.111-125
• /
• 2022

Since landslide can cause huge damages to many facilities, close characterization of slopes is needed for appropriate reinforcements for the unstable ones in order to prevent the damages. Geophysical surveys, which can characterize a large area at a relatively low cost without disturbing slopes, have been widely employed for the assessment of slope stability in other countries. However, only conventional direct investigation methods are mainly used in Korea. In this paper, we analyzed various cases, which evaluated slope stabilities by characterizing slopes using geophysical exploration. First, we introduced changes in geophysical properties due to unstable media of slope like fracture location, fracture connectivity and distribution of groundwater level, and subsequently discussed the applicability of geophysical methods to the detection of the changes; the methods include electrical resistivity survey, seismic survey, self-potential survey, induced polarization survey and ground penetrating radar. Based on this description, we analyzed how geophysical surveys were performed on various slopes.

• Journal of Korean Society of Forest Science
• /
• v.112 no.1
• /
• pp.11-22
• /
• 2023

This study was established to provide basic information necessary for ecological management to restore the naturalness of black locust (Robinia pseudoacacia L.) plantations located in the mountains of Gyeongbuk, Korea. Using vegetation data collected from 200 black locust stands, vegetation types were classified using the TWINSPAN method, the spatial arrangement status according to the environmental gradient was identified through DCA analysis, and a synoptic table of communities was prepared based on the diagnostic species determined by determining community fidelity (Φ) for each vegetation type. The vegetation types were classified into seven types, namely, Quercus mongolica-Polygonatum odoratum var. pluriflorum type, Castanea crenata-Smilax china type, Clematis apiifolia-Lonicera japonica type, Rosa multiflora-Artemisia indica type, Quercus variabilis-Lindera glauca type, Ulmus parvifolia-Celtis sinensis type, and Prunus padus-Celastrus flagellaris type. These types usually reflected differences in complex factors such as altitude, moisture regime, successional stage, and disturbance regime. The mean relative importance value of the constituent species was highest for black locust(39.7), but oaks such as Quercus variabilis, Q. serrata, Q. mongolica, Q. acutissima, and Q. aliena were also identified as important constituent species with high relative importance values, indicating their potential for successional trends. In addition, the total percent cover of constituent species by vegetation type, life form composition, species diversity index, and indicator species were compared.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.6
• /
• pp.77-84
• /
• 2008

The existing equations for radial consolidation cannot account for the changes of well resistance with time and cannot predict the appropriate in-situ consolidation curve. In this study, small cylinder cell tests are performed to evaluate the discharge capacity of PVD. Also, a block sample of 1.2 m in diameter and 2.0 m in height was consolidated to observe the change in the drainage capacity with time for three types of PVD. From the test results on a block sample, the drainage curves normalized with initial drainage of each PVD are similar, regardless of the PVD type and the consolidation curve, which is predicted using solutions of radial consolidation based on the discharge capacity measured in a small cylinder cell tests, significantly overestimates the degree of consolidation. The term of well resistance in the radial consolidation solution was back-calculated to fit the consolidation curve of a large block sample and it is defined as the time dependent well resistance factor, L(t). The L(t) was found to be linearly proportional to the dimensionless time factor, Th. It was also shown that the consolidation curve evaluated by using L(t) provides more accurate prediction than the existing solution.