• Journal of the Korean Geosynthetics Society
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• v.21 no.2
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• pp.31-38
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• 2022

Recently, irregular torrential rainfall have frequently occurred due to abnormal climate, and landslide damage is increasing. In Korea, more than 70% of the total land is mountainous areas, appropriate measures are needed to prevent landslides by heavy rainfall. When improved soil is applied to the surface of the slope, it is possible to suppress an increase in groundwater level due to rainfall penetration and secure stability of the slope. In this study, the appropriate depth of improved soil that can confirm the increase in groundwater level and secure stability by applying improved soil to the weathered soil slope was studied. A total of three cases were analyzed for the slope of the cross-section: standard slope for weathered soil (1:1.5, 1:1.8, and 1:2.0). For rainfall conditions, referring to the regional frequency probability rainfall provided by the Water resource Management Information System, the increase in groundwater level by stage was confirmed by assuming a 500-year frequency precipitation maximum duration of 48 hours. As a result of the study, in the case of natural slopes, the slope was completely saturated before 48 hours the rainfall duration, and there was a possibility of collapse. the improvement depth in the slope of 1:1.5 was appropriate for more than 1m from the surface regardless of the rainfall duration, and in the the slope of 1:1.8 was appropriate of 1m for more than 36 hours. in the slope of 1:2.0, it was appropriate for that safety when improved soil of 0.5m for rainfall duration 48 hours or more.

• Korean Journal of Acupuncture
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• v.39 no.4
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• pp.152-171
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• 2022

Objectives : This study was designed to investigate the effects of Sunbanghwalmyung-eum gamibang on Monosodium iodoacetate-induced osteoarthritis rats. Methods : Forty Sprague-Dawley (SD) rats were divided into 5 groups of 8 rats each. Osteoarthritis (OA) was induced by injecting MIA (2 mg/50 µl) into the joint cavity of the left knee of SD rats belonging to the experimental group, and normal saline was injected into the joint cavity of the left knee instead of MIA in the normal group. To the normal group and the controlled group (OA group), 2 ml of distilled water was orally administered. To the positive control group (Indomethacin group), indomethacin 2 ml at a concentration of 2 mg/kg, to the low concentration group of SHG (Low group), 2 ml of SHG at a concentration of 2 mg/kg, and to the high concentration group of SHG (High group), 2 ml of SHG at a concentration of 4 mg/kg ml was orally administered. The drug was administered for a total of 4 weeks, and histological changes were analyzed by Hematoxylin-Eosin staining and Safranin-O staining. In addition, inflammatory cytokines such as TNF-α, IL-1β, and IL-6, and MMP-13, TIMP-1, and GAGs were immunohistochemically analyzed. Finally, hematological examination, blood biochemical examination, and liver and kidney biopsy were performed. Results : SHG groups (Low and High) inhibited the matrix destruction and damage of the knee joint cartilage in SD rat model, and significantly prevented the reduction in cartilage thickness. In SHG groups, the expressions of TNF-α, IL-1β, IL-6 and MMP-13 were significantly decreased, and the expressions of TIMP-1, GAGs were significantly increased compared with OA group. The safety indicators had no significant differences among five groups. Conclusions : These results show that SHG has cartilage protection capacity, anti-inflammatory effect.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.665-672
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• 2023

Purpose: Underground utility tunnel is facility that is jointly house infrastructure such as electricity, water and gas in city, causing condensation problems due to lack of airflow. This paper aims to prevent electricity leakage fires caused by condensation by detecting whether the control panel door in the underground utility tunnel is open using a deep learning model. Method: YOLO, a deep learning object recognition model, is trained to recognize the opening and closing of the control panel door using video data taken by a robot patrolling the underground utility tunnel. To improve the recognition rate, image augmentation is used. Result: Among the image enhancement techniques, we compared the performance of the YOLO model trained using mosaic with that of the YOLO model without mosaic, and found that the mosaic technique performed better. The mAP for all classes were 0.994, which is high evaluation result. Conclusion: It was able to detect the control panel even when there were lights off or other objects in the underground cavity. This allows you to effectively manage the underground utility tunnel and prevent disasters.

• Clean Technology
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• v.16 no.4
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• pp.258-264
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• 2010

This study estimated the possibility of phosphate removal characteristics to utilize EAF(electric arc furnace) slag as submarine cover material. The major phosphate removal mechanism was a certain formation of HAP precipitation occurred by the ionization reaction between $Ca^{2+}$ and $OH^-$, which were leached from the EAF Slag. Another phosphate removal mechanism was the adsortion of EAF slag surface. As a result of $PO_4{^-}-P$ removal characteristics using continuous column reactor, $PO_4{^-}-P$ concentration decreased rapidly after 3 days and 10 days later, it show under 0.5 ppm. The result as applied in real sea water, shows that the phosphate removal effects were 93~98% by the subaqueous sediment removal using the EAF slag. In conclusion, EAF slag is useful in $PO_4{^-}-P$ removal and control and it is possible to use without additional process like crush and selection.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.295-303
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• 2023

South Korea has recently witnessed an increasing number of seismic events, leading to a surge in studies focusing on seismic earth pressures, as well as the attributes of geological layers and ground where foundations are established. Consequently, earthquake-resistant design has become imperative to ensure the safety of subterranean structures. The slurry wall method, due to its superior wall rigidity, excellent water resistance, and minimal noise and vibration, is often employed in constructing high-rise buildings in urban areas. However, given the separation between panels that constitute the wall, slurry walls possess limited resistance to seismic loads in the longitudinal direction. As a solution, several studies have probed into the possibility of interconnecting slurry wall panels to augment their seismic performance. In this research, we developed and evaluated a method for linking slurry wall panels using mechanical joints, including concrete-confined steel pipes and headed bars, through mock-up tests. We also assessed the constructability of the suggested method and compared it with other analogous methods. Any challenges identified during the mock-up test were discussed to guide future research in resolving them. The results of this study aid in enhancing the seismic performance of slurry walls through the development of an interconnected panel method. Further research can build on these findings to address the identified issues and improve the efficacy and reliability of the proposed method.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4571-4584
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• 2022

The analysis of rapid flow transients in Reactor Coolant Pumps (RCP) is essential for a reactor safety study. An accurate and precise analysis of the RCP coastdown is necessary for the reactor design. The coastdown of RCP affects the coolant temperature and the colloidal crud in the primary coolant. A realistic and kinetic model has been used to investigate the behavior of activated colloidal crud in the primary coolant and steam generator that solves the pump speed analytically. The analytic solution of the non-dimensional flow rate has been determined by the energy ratio β. The kinetic energy of the coolant fluid and the kinetic energy stored in the rotating parts of a pump are two essential parameters in the form of β. Under normal operation, the pump's speed and moment of inertia are constant. However, in a coastdown situation, kinetic damping in the interval has been implemented. A dynamic model ACCP-SMART has been developed for System Integrated Modular and Advanced Reactor (SMART) to investigate the corrosion due to activated colloidal crud. The Fickian diffusion model has been implemented as the reference corrosion model for the constituent component of the primary loop of the SMART reactor. The activated colloidal crud activity in the primary coolant and steam generator of the SMART reactor has been studied for different equilibrium corrosion rates, linear increase in corrosion rate, and dynamic RCP coastdown situation energy ratio b. The coolant specific activity of SMART reactor equilibrium corrosion (4.0 mg s^-1) has been found 9.63×10^-3 µCi cm^-3, 3.53×10^-3 µC cm^-3, 2.39×10^-2 µC cm^-3, 8.10×10^-3 µC cm^-3, 6.77× 10^-3 µC cm^-3, 4.95×10^-4 µC cm^-3, 1.19×10^-3 µC cm^-3, and 7.87×10^-4 µC cm^-3 for ²⁴Na, ⁵⁴Mn, ⁵⁶Mn, ⁵⁹Fe, ⁵⁸Co, ⁶⁰Co, ⁹⁹Mo, and ⁵¹Cr which are 14.95%, 5.48%, 37.08%, 12.57%, 10.51%, 0.77%, 18.50%, and 0.12% respectively. For linear and exponential coastdown with a constant corrosion rate, the total coolant and steam generator activity approaches a higher saturation value than the normal values. The coolant and steam generator activity changes considerably with kinetic corrosion rate, equilibrium corrosion, growth of corrosion rate (ΔC/Δt), and RCP coastdown situations. The effect of the RCP coastdown on the specific activity of the steam generators is smeared by linearly rising corrosion rates, equilibrium corrosion, and rapid coasting down of the RCP. However, the time taken to reach the saturation activity is also influenced by the slope of corrosion rate, coastdown situation, equilibrium corrosion rate, and energy ratio β.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.27-40
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• 2006

Damage of cut-and-cover tunnel lining can be attributed to physical and mechanical factors. Physical factors include material property, reinforcement corrosion, etc. while mechanical factors include underground water pressure, vehicle loads, etc. This study is limited to the modeling of rigid circular cut and cover tunnel constructed at a depth of $1.0{\sim}1.5D$ in loose sandy ground and subjected to a vibration frequency of 100 Hz. In this study, only damages due to mechanical factors in the form of additional loads were considered. Among the different types of additional, excessive earth pressure acting on the cut-and-cover tunnel lining is considered as one of the major factors that induce deformation and damage of tunnels after the construction is completed. Excessive earth pressure may be attributed to insufficient compaction, consolidation due to self-weight of backfill soil, precipitation and vibration caused by traffic. Laboratory tunnel model tests were performed in order to determine the earth pressure acting on the tunnel lining and to investigate the applicability of existing earth pressure formulas. Based on the difference in the monitored and computed earth pressure, a factor of safety was recommended. Soil deformation mechanism around the tunnel was also presented using the picture analysis method.

• Journal of the Korean Geotechnical Society
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• v.25 no.1
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• pp.65-76
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• 2009

The unsaturated characteristics of Korean weathered granite soils have been studied to investigate the influence of saturated permeability, rainfall intensity and soil-water characteristic curve (SWCC) on the slope stability. The upper, average and lower SWCCs were estimated from the publication and experimental results using the statistical concept. The roughly estimated SWCC can be used for the soils without experimental results by relating SWCC with the particle size distribution curve. An appropriate ratio between the saturated permeability and the rainfall intensity ($k_s$/i) was also suggested for practical use in designing the slopes by investigating the time-dependent variation of slope instability during the rainfall. The slope stability was deteriorated from the initiation of rainfall and recovered again after the factor of safety reached the critical value. The FS of the slope decreased at first and then increased after reaching the critical value during the rainfall. As a result, the slope instability was not related with an absolute rainfall intensity but with the ratio between the saturated permeability and the rainfall intensity. In case of the upper SWCC, the critical condition occurred when the ratio between the saturated permeability and the rainfall intensity was in the range of $1.0{\sim}2.0$.

• Journal of the Korean GEO-environmental Society
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• v.23 no.4
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• pp.5-10
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• 2022

Recently, ground subsidence has been continuously occurring in downtown areas, threatening the safety of citizens. Various underground facilities such as water and sewage pipelines and communication pipelines are buried under the road. It is reported that the cause of ground subsidence is the deterioration of various facilities and the reckless development of the underground. In particular, it is known that the biggest cause of ground subsidence is the aging of sewage pipelines. As an existing study related to this, several representative factors of sewage pipelines were selected and a study to predict the risk of ground subsidence through statistical analysis has been conducted. In this study, a data SET was constructed using the characteristics of OO city's sewage pipe characteristics and ground subsidence data, The data set constructed from the characteristics of the sewage pipe of OO city and the location of the ground subsidence was used. The goal of this study was to present a classification model for the occurrence of ground subsidence according to the characteristics of sewage pipes through machine learning. In addition, the importance of each sewage pipe characteristic affecting the ground subsidence was calculated.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.57-67
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• 2023

Slope failures during rainfall have been observed in mountainous areas of South Korea as a result of the presence of solar power facilities. The seepage behavior and pore pressure distribution differ from typical slopes due to the presence of impermeable solar panels, and the load imposed by the solar power structures also affects the slope behavior. This study aims to develop a method for evaluating the stability of slopes with solar power facilities and to analyze vulnerable points by considering the maximum slope displacement. To assess the slope stability and predict behavior while considering rainfall seepage, a combined seepage analysis and finite difference method numerical analysis were employed. For the selected site, various variables were assumed, including parameters related to the Soil Water Characteristic Curve, strength parameters that satisfy the Mohr-Coulomb failure criterion, soil properties, and topographic factors such as slope angle and bedrock depth. The factors with the most significant influence on the factor of safety (FOS) were identified. The presence of solar power facilities was found to affect the seepage distribution and FOS, resulting in a decreasing trend due to rainfall seepage. The maximum displacement points were concentrated near the upper (crest) and lower (toe) sections of the slope.