• Journal of the Korean GEO-environmental Society
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• v.24 no.8
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• pp.5-11
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• 2023

Due to frequent occurrences of concentrated heavy rainfall caused by abnormal climate conditions in recent years, collapses of steep slopes have been occurring frequently due to surface erosion and increased pore water pressure. Various methods are being applied to prevent slope collapses, such as increasing the resistance to movement and reducing pore water pressure. Research on these methods has been consistently conducted as they provide an efficient response to slope collapses by satisfying both the conditions of resistance to movement and pore water pressure simultaneously. Therefore, in this study, we propose an upward slope reinforcement method by burying drainage materials with an upward slope inclination, instead of the conventional horizontal application. This approach aims to satisfy both slope reinforcement and drainage functions effectively, offering a comprehensive solution for slope stabilization. Furthermore, to determine the optimal burial angle that exhibits the most effective reinforcement and drainage effects of the proposed method, we investigated the reinforcement and drainage effects under conditions where the horizontal drainage materials were set at angles ranging from 0° to 60° in increments of 10° on a representative cross-section. Additionally, indoor model experiments were conducted under the conditions of 40°, which showed the most outstanding drainage effect, and 20°, which exhibited the highest safety factor, to validate the numerical analysis results. The results showed that the burial angle of 40° exhibits a relatively higher drainage effect as with the numerical analysis results, while the angle of 20° results in inadequate drainage and observed slope collapse.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.133-142
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• 2006

Many methods have been tried to more correctly measure rock joint roughness. However, true roughness may be distorted and underestimated due to the sampling interval and measurement method. Thus, currently used measurement methods produce a dead zone and distort roughness profiles. The purpose of this study is to suggest new roughness measurement method by a camera-type 3D scanner as an alternative of currently used methods. First, the underestimation of artificial roughness is analyzed by using the current measurement method such as laser profilometry. Second, we replicate eight specimens from two rock joint surfaces, and digitize by a 3D scanner. Then, the roughness coefficient values obtained from eight numbers of 3D surface data and from three hundred twenty numbers of 2D profiles data are analyzed by using current and new measurement methods. The artificial simulation confirms that the sampling interval is one of main factors for the distortion of roughness and shows that inclination of waviness may not be considered any current methods. The experimental results show that the camera-type 3D scanner produces 10% larger roughness values than current methods. As the proposed new method is a fast, high precision and more accurate method for the roughness measurement, it should be a promising technique in this area.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1C
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• pp.45-51
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• 2010

In urban area, design and construction of civil engineering structures such as subway tunnel, underground space and deep excavation is impeded by unreliable site investigation. Variety of embedded objects, electric noises and traffic vibrations degrades the quality of site investigation, whatever the site-investigation technique would be. In this research, a preliminary research was performed to develop a dedicated site investigation technique for urban geotechnical sites, which can overcome the limitations of urban sites. HiRAS (Hybrid Integration of Surface Waves and Resistivity) technique which is the first outcome of the preliminary research was proposed in this paper. The technique combines surface wave as well as electrical resistivity. CapSASW method for surface-wave technique and PDC-R technique for electrical resistivity survey were incorporated to develop HiRAS technique. CapSASW method is a good method for evaluating material stiffness and PDC-R technique is a reliable method for determination of underground stratification even in a site with electrical noise. For the inversion analysis of HiRAS techniuqe, a site-specific relationship between stress-wave velocity and resistivity was employed. As for outgrowth of this research, the 2-D distribution of Poisson's ratio could be also determined.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1C
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• pp.37-44
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• 2010

Recently, urban retrofit and extension, development of new buildings and facilities, and construction of underground structures like subway tunnels in urban areas give rise to significance of site investigation at urban areas. However, ambient electric noises, traffic vibrations, embedded objects work as obstacles to high-quality and accuracy in site investigation at urban areas. In this paper, a new technique called the pseudo-DC resistivity survey (in brief, PDC-R) was proposed to minimize the adverse effect of ambient electrical noises in resistivity survey. PDC-R technique utilizes an AC current with frequency range of 0.1 to 1.0 Hz rather than DC current, which is used for conventional resistivity survey. The motivation of using low-frequency AC current is to avoid 60-Hz components or its multiples in the resistivity survey which ambient noises are mostly composed of. The implementation of PDC-R technique also included the parametric study on skin effect, frequency effect and current-level effect, which led to the determination of optimal values of frequency and current level for PDC-R survey. The reliability and feasibility of PDC-R technique was verified through field tests, accompanied by the comparison with DC resistivity survey and CapSASW tests.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4B
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• pp.363-369
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• 2006

A simple and an improved methods for the economic analysis of the flood control project has been in previous studies in Korea. In 2004, the Multi-Dimensional Flood Damage Analysis (MD-FDA) was developed and now it is widely used for the economic analysis of flood control project. However, the MD-FDA was developed for general damage assessment and analysis without consideration of specific regional characteristics such as urban and rural areas. To compensate the MD-FDA for the application in urban area, a part of damage estimation components is modified and a component for the flood damage estimation is suggested. The component we suggest is for the consideration of the capability of stormwater pump stations in the study area. When flood is occurred in the urban area, the damage potential is larger than the rural area because of the concentration of human lives and properties. So, many stormwater pump stations are located in the urban area and the inundation depth is estimated by considering the capabilities of pump stations. We also compensate the damage components such as the damages of industrial area, and public facilities for the flood damage estimation of the urban area. The results by the compensated MD-FDA for the urban area application with those by original MD-FDA are compared. As a result the B/C ratio showed 6.75 and 5.51 respectively for the modified and original MD-FDA. This difference might be largely affected by the damage rate of the public facilities.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.12
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• pp.937-946
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• 2017

Recently, urban structures including buildings are becoming increasingly large and super high-rise in order to make human life more convenient. As the number of super high-rise buildings increases, however, the risk of fire and other disasters is increasing. Especially, it is expected that deaths and injuries will be tremendous than imagined if the evacuation guidance is not provided promptly and precisely for the occupants in case of a fire in super high-rise buildings. Therefore, rapid rescue should be done for those who are in need of residence or rescue in the building. To do this, identification of the size and location of people inside the building should be preceded. To do this, first, we conduct a preliminary study on existing location tracking technologies to identify occupants. Based on this, in this paper, we will study how to improve evacuation time in case of a fire in super high-rise buildings. For this purpose, we utilize the location tracking technology to identify the number of people in real time and improve the density when a disaster such as a fire occurs.

• Smart Media Journal
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• v.12 no.10
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• pp.102-109
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• 2023

This study aimed to investigate the growth parameters and antioxidant activity of Cnidium officinale under controlled temperature and carbon dioxide levels during the cultivation period. The plants were cultivated for four months, each group being set at the average temperature of the cultivation area +1.8℃/445ppm(SSP1), +3.6℃/872ppm(SSP3), and +4.4℃/1,142ppm(SSP5), respectively. During the cultivation period, the growth, Top/Root ratio, and leaf weight ratio(LWR) of C. officinale slightly decreased in SSP3 and SSP5 compared to SSP1, while the root weight ratio(RWR) increased. The antioxidant activity and related phenolic compound content in the aerial parts of C. officinale increased proportionally with temperature and CO₂ concentration. However, an adverse effect was observed in the high-concentration SSP5 group. Conversely, in the roots, the SSP5 group exhibited the highest antioxidant activity. This study suggests that it can be utilized as fundamental data necessary for understanding the correlation between environmental conditions and the growth as well as physiological activities of medicinal plants.

• Smart Media Journal
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• v.12 no.10
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• pp.93-101
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• 2023

Climate change has emerged as a global problem, with frequent temperature increases, droughts, and floods, and it is predicted that it will have a great impact on the characteristics and productivity of crops. Cnidium officinale is used not only as traditionally used herbal medicines, but also as various industrial raw materials such as health functional foods, natural medicines, and living materials, but productivity is decreasing due to threats such as continuous crop damage and climate change. Therefore, this paper proposes a model that can predict the physiologically active ingredient index according to the climate change scenario of Cnidium officinale, a representative medicinal crop vulnerable to climate change. In this paper, data was first augmented using the CTGAN algorithm to solve the problem of data imbalance in the collection of environment information, physiological reactions, and physiological active ingredient information. Column Shape and Column Pair Trends were used to measure augmented data quality, and overall quality of 88% was achieved on average. In addition, five models RF, SVR, XGBoost, AdaBoost, and LightBGM were used to predict phenol and flavonoid content by dividing them into ground and underground using augmented data. As a result of model evaluation, the XGBoost model showed the best performance in predicting the physiological active ingredients of the sacrum, and it was confirmed to be about twice as accurate as the SVR model.

• Journal of the Korean earth science society
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• v.44 no.6
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• pp.629-642
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• 2023

Currently, low and intermediate level radioactive waste is being disposed of at the Gyeongju disposal site for permanent isolation. Since 2006, the Korea Radioactive Waste Agency has been conducting site characteristics surveys continuously verifying changes in the site based on the site monitoring and investigation plan. The hydrogeochemical environment of the disposal site is considered for the evaluation of natural barriers. However, the seawater must be considered because of the regional characteristics of Gyeongju, which is near the East Sea. Therefore, this study, collected 30 samples for deriving the groundwater quality data from seven wells and compared with two seawater samples collected from October 2017 to June 2022. Additionally, the study explores the groundwater monitoring method using statistical tools such as clustering and background concentration analysis. The groundwater samples in the study area were classified into two to four clusters depending on their chemical constituents-especially, EC, HCO₃, Na, and Cl-using statistical analysis, molar ratio, and K-means clustering.

• Geophysics and Geophysical Exploration
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• v.26 no.4
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• pp.229-237
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• 2023

The use of artificial sources such as explosives and mechanical vibrations for seismic exploration in urban areas poses challenges, as the vibrations and noise generated can lead to complaints. As an alternative to artificial sources, the surface waves generated by traffic noise can be used to investigate the subsurface properties of urban areas. However, traffic noise takes the form of plane waves moving continuously at a constant speed. To apply existing surface wave processing/inversion techniques to traffic noise, the recorded data need to be transformed into a virtual shot gather format using seismic interferometry. In this study, various seismic interferometry methods were applied to traffic noise data, and the optimal method was derived by comparing the results in the Radon and F-K domains. Additionally, the data acquired using various receiver arrays were processed using seismic interferometry, and the results were compared and analyzed to determine the most optimal receiver array direction for exploration.