• Tunnel and Underground Space
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• v.29 no.4
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• pp.262-279
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• 2019

In the engineering barriers of high-level radioactive waste disposal, gases could be generated through a number of processes. If the gas production rate exceeds the gas diffusion rate, the pressure of the gas increases and gases could migrate through the bentonite buffer. Because people and the environment can be exposed to radioactivity, it is very important to clarify gas migration in terms of long-term integrity of the engineered barrier system. In particular, it is necessary to identify the hydro-mechanical mechanism for the dilation flow, which is a very important gas flow phenomenon only in medium containing large amounts of clay materials such as bentonite buffer, and to develop and validate new numerical approach for the quantitative evaluation of the gas migration phenomenon. Therefore, in this study, we developed a two-phase flow model considering the mechanical damage model in order to simulate the gas migration in the engineered barrier system, and validated with 1D gas flow modelling through saturated bentonite under constant volume boundary conditions. As a result of numerical analysis, the rapid increase in pore water pressure, stress, and gas outflow could be simulated when the dilation flow was occurred.

• Laboraroty Animal Research
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• v.34 no.4
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• pp.317-328
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• 2018

Cognitive impairment responses are important research topics in the study of degenerative brain diseases as well as in understanding of human mental activities. To compare response to scopolamine (SPL)-induced cognitive impairment, we measured altered parameters for learning and memory ability, inflammatory response, oxidative stress, cholinergic dysfunction and neuronal cell damages, in Korl:ICR stock and two commercial breeder stocks (A:ICR and B:ICR) after relevant SPL exposure. In the water maze test, Korl:ICR showed no significant difference in SPL-induced learning and memory impairment compared to the two different ICRs, although escape latency was increased after SPL exposure. Although behavioral assessment using the manual avoidance test revealed reduced latency in all ICR mice after SPL treatment as compared to Vehicle, no differences were observed between the three ICR stocks. To determine cholinergic dysfunction induction by SPL exposure, activity of acetylcholinesterase (AChE) assessed in the three ICR stocks revealed no difference of acetylcholinesterase activity. Furthermore, low levels of superoxide dismutase (SOD) activity and high levels of inflammatory cytokines in SPL-treated group were maintained in all three ICR stocks, although some variations were observed between the SPL-treated groups. Neuronal cell damages induced by SPL showed similar response in all three ICR stocks, as assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, Nissl staining analysis and expression analyses of apoptosis-related proteins. Thus, the results of this study provide strong evidence that Korl:ICR is similar to the other two ICR. Stocks in response to learning and memory capacity.

• Journal of the Korean GEO-environmental Society
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• v.12 no.12
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• pp.79-88
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• 2011

Adfreeze bond strength develops upon freezing of pore water within soil and at foundation surface. It has been reported that various factors like temperature, soil type, and pile surface roughness affect adfreeze bond strength. Especially, pile surface roughness has been considered as a primary factor to design pile foundation in frozen ground. It has usually been estimated with fixed correction factors for pile materials. However, even if the pile foundation material is the same, the surface roughness could vary depending on the production circumstances. In this study, laboratory test was carried out to quantitatively analyze the effects of surface roughness on the adfreeze bond strength, and fractal dimension was used as a measure for surface roughness. Test results showed that adfreeze bond strength increased with decreasing temperature, increasing vertical stress and surface roughness. The adfreeze bond strength varies sensitively with surface roughness in the early freezing section of $-2^{\circ}C$, but its sensitivity decreased in the temperature ranging between $-2^{\circ}C$ to $-5^{\circ}C$. The results conclude that the roughness highly affects the frictional resistance of pile surface in frozen ground; however, the roughness does not affect considerably when the temperature drops below about $-2^{\circ}C$.

• Journal of Korean Medicine Rehabilitation
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• v.31 no.1
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• pp.17-32
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• 2021

Objectives The present study was designed to find out the therapeutic effects and possible underlying mechanism of Buja-tang, a herbal complex formula on experimental monosodium iodoacetate (MIA)-induced osteoarthritis. Methods Osteoarthritis models were created via intra-joint injection of MIA (50 μL with 80 mg/mL) in rats. Rats were divided into five groups and each group consisted of seven. Normal group was not injected MIA and did a normal diet. Control group injected MIA and received distilled water. Indo injected MIA and oral administration of 5 mg/kg of indomethacin. BJTL injected MIA and oral administration of 100 mg/kg of Buja-tang. BJTH injected MIA and oral administration of 200 mg/kg of Buja-tang. We analyzed weight-bearing ability of hind paws, oxidative stress related factor, antioxidant protein, inflammatory protein, inflammatory messenger and cytokine in joint tissue. Pathological observation of knee cartilage tissue structures was also performed with hematoxylin & eosin and safranin-O chromosomes. Results Weight-bearing ability of hind paws showed a tendency to reduce pain. The incidence of nicotinamide adenine dinucleotide phosphate oxidase and p22phox in articular tissue was significantly reduced, and the incidence of nuclear factor-erythroid 2-related factor 2 and heme oxygenase-1 and superoxide dismutases was significantly increased. The incidence of phosphorylated inhibitor of κBα, nuclear factor-kappa B p65, inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis factor alpha, interleukin (IL)-6, and IL-1β decreased significantly. In pathological observation, cartilage tissue damaged by MIAs in biopsy has significantly recovered from Buja-tang administration. Conclusions Buja-tang has anti-inflammation, antioxidation and pain relief effects. So this is thought to inhibit the progress of osteoarthritis in rat caused by the MIA.

• The Journal of Engineering Geology
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• v.31 no.2
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• pp.199-209
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• 2021

This paper is written to evaluate the ground stability according to the construction of Jeju 2nd airport. Sumgol is the unique characteristics of Jeju soil, which is used to evaluate the ground stability of the airport. The research contents are as follows. 1) The geotechnical characteristics for Jeju 2nd airport was analyzed, and the Sumgol and geotechnical properties were calculated based on the existing geotechnical survey data. 2) The divided sections of Jeju 2nd airport were modeled to evaluate the ground stability after determining the section (runway and airport facilities) which have the different soil and loading properties. 3) The stability and deformation ranges of the airport ground were identified through numerical analysis. The entire airport was divided into three sections to analyze the stability of Jeju 2nd airport, and calculated the stresses, settlements, and strains of each section by computer numerical analysis modeling. For modeling, the ground and load conditions were examined, also pavement conditions for each airport ground section were examined. From the analysis results of each section according to the ground conditions, the vertical settlements were analyzed as 0.11~0.18 m and the sum of effective stress and pore water pressure were 92.75~445 kPa. These results were made by taking into account the Sumgol of the bottom ground without reinforcement, also the soil strength parameters of the airport ground were reduced for computer modeling, Therefore, if proper reinforcements are applied to the ground of Jeju 2nd airport, sufficient airport ground stability can be secured.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.632-638
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• 2022

As Korean coastal activity is high, the incidence of accidents caused by marine waste is extensive. An accident in which marine floating waste ropes and fishing nets are wound around the propeller of a sailing ship is termed "Rope wrapped accident." To prevent such accidents, this study applied the Finite Element Method (F.E.M.) for performance evaluation of the shaver type cutter, commercialized in Korea, through a structural safety review and water tank test. The results demonstrate that all parts constituting the rope cutter were damaged before reaching 0.5s, and the safety factor of each part was found to be at least 2 based on the maximum stress generated compared to the tensile strength. In the basin test, the cutting process of the shaver type rope cutter was reviewed, and the installation angle was set for each case considering that the rope floating in the sea actually enters at various angles. Consequently, as it was successful at cutting in all the cases, it can be concluded that there will be no problem in cutting the rope regardless of the mounted angle of the cutting blade.

• Journal of the Korean Geotechnical Society
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• v.38 no.4
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• pp.59-70
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• 2022

There is a growing interest in evaluating earthquake damage and determining disaster prevention measures due to the magnitude 5.8 earthquake in Pohang, Korea. Since the liquefaction phenomena occurred extensively in the residential area as a result of the earthquake, there was a demand for research on liquefaction phenomenon evaluation and liquefaction disaster prediction. Liquefaction is defined as a phenomenon where the strength of the ground is completely lost due to a sudden increase in excess pore water pressure caused due to large dynamic stress, such as an earthquake, acting on loose sand particles in a short period of time. The liquefaction potential index, which can identify the occurrence of liquefaction and predict the risk of liquefaction in a targeted area, can be used to create a liquefaction hazard map. However, since liquefaction assessment using existing field testing is predicated on a single borehole liquefaction assessment, there has been a representative issue for the whole targeted area. Spatial interpolation and geographic information systems can help to solve this issue to some extent. Therefore, in order to solve the representative problem of geotechnical information, this research uses the kriging method, one of the geostatistical spatial interpolation techniques, and constructs a geotechnical information database for liquefaction and spatial interpolation. Additionally, the liquefaction hazard map was created for each return period using the constructed geotechnical information database. Cross validation was used to confirm the accuracy of this liquefaction hazard map.

• Journal of Ecology and Environment
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• v.45 no.4
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• pp.277-286
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• 2021

Background: As trade increases, the influx of various alien species and their spread to new regions are prevalent and no longer a special problem. Anthropogenic activities and climate changes have made the distribution of alien species out of their native range common. As a result, alien species can be easily found anywhere, and they have nothing but only a few differences in intensity. The prevalent distribution of alien species adversely affects the ecosystem, and a strategic management plan must be established to control them effectively. To this end, hot spots and cold spots were analyzed according to the degree of distribution of invasive alien plants, and major environmental factors related to hot spots were found. We analyzed the 10,287 distribution points of 126 species of alien plants collected through the national survey of alien species by the hierarchical model of species communities (HMSC) framework. Results: The explanatory and fourfold cross-validation predictive power of the model were 0.91 and 0.75 as AUC values, respectively. The hot spots of invasive plants were found in the Seoul metropolitan area, Daegu metropolitan city, Chungcheongbuk-do Province, southwest shore, and Jeju island. Generally, the hot spots were found where the higher maximum temperature of summer, precipitation of winter, and road density are observed, but temperature seasonality, annual temperature range, precipitation of the summer, and distance to river and sea were negatively related to the hot spots. According to the model, the functional traits accounted for 55% of the variance explained by the environmental factors. The species with higher specific leaf areas were more found where temperature seasonality was low. Taller species preferred the bigger annual temperature range. The heavier seed mass was only preferred when the max temperature of summer exceeded 29 ℃. Conclusions: In this study, hot spots were places where 2.1 times more alien plants were distributed on average than non-hot spots (33.5 vs 15.7 species). The hot spots of invasive plants were expected to appear in less stressful climate conditions, such as low fluctuation of temperature and precipitation. Also, the disturbance by anthropogenic factors or water flow had positive influences on the hot spots. These results were consistent with the previous reports about the ruderal or competitive strategies of invasive plants instead of the stress-tolerant strategy. The functional traits are closely related to the ecological strategies of plants by shaping the response of species to various environmental filters, and our result confirmed this. Therefore, in order to effectively control alien plants, it is judged that the occurrence of disturbed sites in which alien plants can grow in large quantities is minimized, and the river management of waterfronts is required.

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.493-506
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• 2021

Liquefaction refers to a phenomenon in which excessive pore water pressure occurs when a dynamic load such as an earthquake rapidly acts on a loose sandy soil saturated with soil, and the ground loses effective stress and becomes liquefied. The indoor repeated test for liquefaction evaluation can be confirmed through the repeated triaxial compression test and the repeated shear test. In this regard, this study tried to confirm the liquefaction resistance strength according to the relative density and particle size distribution of sand using the repeated triaxial compression test. As a result of the experiment, it was confirmed that the liquefaction resistance strength increased as the relative density increased regardless of the soil classification, and the liquefaction resistance strength according to the particle size distribution of the sand was confirmed that the liquefaction resistance strength of the SP sample close to SW was significantly higher. In addition, as a result of analyzing 30% of fine powder compared to 0% of fine powder, as the relative density increased to 40~70%, the liquefaction resistance strength decreased by 5~20%, and the domestic weathered soil ground had a fine liquefaction resistance strength compared to Jumunjin standard sand. When the minute was 10%, it was measured to be 30% or more, and when the fine particle was 30%, it was measured to be less than 50%.

• The Korea Journal of Herbology
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• v.33 no.6
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• pp.19-28
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• 2018

Objectives : The objective of this study was to investigate the protective effect of Flaxseed oil and Chrysanthemi Indici Flos 50% ethanol extract in an HCl/ethanol induced acute gastritis model. Methods : ICR mice were divided into 6 groups; normal mice (Nor), gastritic mice with distilled water (Veh), gastritic mice with 10 mg/kg sucralfate (SC), gastritic mice with 16 g/㎏ Flaxseed oil (FO), gastritic mice with FO + 50 mg/kg Chrysanthemi Indici Flos (FCL), and gastritic mice with FO + 100 mg/kg Chrysanthemi Indici Flos (FCH). Then, mice were orally administered with 150 mM HCl/60% ethanol and caused acute gastritis. After 1 hr, mice were sacrificed, and blood and stomach tissue were collected. Results : Administration of FCL and FCH to mice prior to the induction of gastritis was found to reduce gastric injury. reactive oxygen species (ROS) and peroxy nitrite ($ONOO^-$) levels of stomach tissues were significantly decreased in FO, FCL, and FCH compared to Veh group. As results of stomach protein analyses, FCL and FCH effectively reduce inflammatory-related factors such as inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), and interleukin 1 beta ($IL-1{\beta}$) in gastric lesion mice. In addition, nuclear factor kappa B p65 ($NF-{\kappa}B$ p65) and phosphorylation inhibitor of nuclear factor kappa $B{\alpha}(p-I{\kappa}B{\alpha})$ were down-regulated in FCL and FCH administrated gastric lesion mice. Conclusions : These results suggest that FCL and FCH has an inhibitory effect against gastric injury. Therefore, FCL and FCH has the potential to be used as a natural therapeutic drug.