• Korean Journal of Soil Science and Fertilizer
• /
• v.43 no.6
• /
• pp.776-781
• /
• 2010

Estimating the electrical conductivity of the saturation-paste (SP) is a common method to assess soil salinity. To assess soil salinity realistically, it is important to extract soil solution under field capacity. However, few studies on salinity assessment have been conducted for soil solution extracted under field capacity (-33 kPa; FC) moisture condition due to difficulty in soil solution extraction. This study was conducted to evaluate whether saturation-paste can represent field condition. Soil solutions were extracted from 22 soils in the plastic film house (PFH) and 18 soils in the reclaimed land (RL) at saturation and field capacity moisture conditions. Those were analyzed for pH, EC, cations ($K^+$, $Ca^{2+}$, $Mg^{2+}$, $Na^+$) and anions ($Cl^-$, ${NO_3}^-$, ${PO_4}^{3-}$, ${SO_4}^{2-}$). Both cations and anions of soil solution extracted from FC showed high correlations with ions extracted from SP in the PFH and the RL, except for ${NO_3}^-$, ${PO_4}^{3-}$ in the RL. Results of the t-test, the ECe and $EC_{FC}$ were not significant at significance level 0.05. The slopes of the equations between $EC_{FC}$ and ECe at more than sand 50% soils were higher than less than sand 50% soils, and differences of saturation percentage between SP and FC showed larger as increasing sand percentage. EC was related to soil water retention by soil texture. To determine the EC, soil texture and other soil properties which effect the soil moisture should be considered.

• Korean Journal of Soil Science and Fertilizer
• /
• v.40 no.1
• /
• pp.12-17
• /
• 2007

This study was conducted to evaluate the characteristics of nonpoint source pollutants discharge from a small rural watershed. A typical rural area in Gongju City, Korea, was selected as the research site. Water quality and quantity in streams and rainfall samples were analyzed periodically from May to October 2005. Pollutant loads were estimated from a nonpoint source pollution model (AvSWAT, Arcview Soil and Water Assessment Tool). During the rainy season, from June 26 to 30 September 2005 and the dry season, before 26 June and after 30 September 2005, biological oxygen demands and chemical oxygen demands accounted for 91.3% and 93.7% of annual load, respectively, while total-N and total-P were 97.1% and 91.1% of annual load, respectively. The observed stream flow was $66.5m^3sec^{-1}$, while simulation stream flow was $66.2m^3sec^{-1}$. That can be assumed that simulation can be used to estimate the stream flow without practical measurement. However, the runoff trend following the occurrence of a storm event was not recorded properly.

• Journal of the Korean Society of Radiology
• /
• v.13 no.2
• /
• pp.185-192
• /
• 2019

DXA is the most commonly used BMD examination equipment with the best performance on reflecting the biological alteration with tiny change of bone density. In spite of the importance of the quality control to maintain the accuracy and precision of the examination, considerable number of hospitals are not conducting QC due to the difficulty and high cost of the phantom product. This study develops the cross revision phantom with 3D printer and the change of the degree of infilling filaments which can be readily secured, and provides the usefulness assessment of the developed phantom by comparing with existing products. The Hounsfield Units of ABS, TPU, PLA, 30% Cu-PLA, and 30% Al-PLA are assessed. The Hounsfield Units result at infilling rate 100% was $-149.74{\pm}2.36$, $-55.62{\pm}7.14$, $-7.68{\pm}3.82$, $87.53{\pm}1.07$, and $1795.20{\pm}16.15$. The L1, L2, L3 BMD of 3D printing phantom with linear regression model were $0.620{\pm}0.010g/cm^2$, $1.092{\pm}0.025g/cm^2$, $1.554{\pm}0.026g/cm^2$ which are statistically relevant to the existing phantom products. This result provides the base line data for various medical phantom produce and capability of proper quality control of DXA equipment.

• Korean Journal of Heritage: History & Science
• /
• v.45 no.1
• /
• pp.70-85
• /
• 2012

Uiseong Tamni-ri Five-storied Stone Pagoda is composed of andesitic tuff and partially combined with tuff breccia and fine-grained granite. The andesitic tuff is identical to basement rock of Geumseongsan Mountain based on lithological, mineralogical and geochemical characteristics. The pagoda has suffered physical weathering such as crack and scaling, discoloration and biological colonization with complex reaction. Expecially, dark gray and brown discoloration appeared whole over the surface of the pagoda, and three to five-layered exfoliation and granular disintegration dominantly occurred in the fourth and fifth roof stones. It is assuming that the stone elements of the pagoda are evaluated as third to forth grades (average third grade) of weathering compared to fresh rock in Geumseongsan Mountain. The physical strength of the stone elements shows low values in the south and west sides of the pagoda that corresponds high weathering degree of the west side due to exfoliation, crack and granular disintegration. It is necessary to investigate the pagoda for precise deterioration assessment, monitoring and conservation treatment.

• Journal of Wetlands Research
• /
• v.21 no.2
• /
• pp.181-190
• /
• 2019

Recently, Low impact development techniques, a form of nature-based solutions (NBS), were seen cost-efficient alternatives that can be utilized as alternatives for conventional stormwater management practices. This study evaluated the effectiveness of an infiltration trench (IT) and a small constructed wetland (SCW) in treating urban stormwater runoff. Long-term monitoring data were observed to assess the seasonal performance and cite the advantages and disadvantages of utilizing the facilities. Analyses revealed that the IT has reduced performance during the summer season due to higher runoff volumes that exceeded the facility's storage volume capacity and caused the facility to overflow. On the other hand, the pollutant removal efficiency of the SCW was impacted by the winter season as a result of dormant biological activities. Sediment data also indicated that fine and medium sand particles mostly constituted the trapped sediments in the pretreatment and media zones. Sediments in SCW exhibited a lower COD and TN load due to the phytoremediation and microbiological degradation capabilities of the system. This study presented brief comparison LID facilities equipped with pre-treatment zones. The identified factors that can potentially affect the performance of the systems were also beneficial in establishing metrics on the utilization of similar types of nature-based stormwater management practices.

• Journal of Biomedical Engineering Research
• /
• v.43 no.5
• /
• pp.331-340
• /
• 2022

Early afterdepolarization (EAD), a significant cause of fatal ventricular arrhythmias including Torsade de Pointes (TdP) in long QT syndromes, is a depolarizing afterpotential at the plateau or repolarization phase in action potential (AP) profile early before completing one pace. AP duration prolongation is related to EAD but is not necessarily accounted for EAD. Several computational studies suggested EAD can form from an abnormality in the late plateau and/or repolarization phase of AP shape. In this sense, we hypothesized the slope during repolarization has the characteristics to predict TdP risk, mainly focusing on the maximum slope during repolarization (dVm/dt_{max_repol}). This study aimed to predict the sensitivity of dVm/dt_{max_repol} to ion channel conductances as a TdP risk metric through a population simulation considering multiple effects of simultaneous reduction in six ion channel conductances of g_NaL, g_Kr, g_Ks, g_to, g_K1, and g_CaL. Additionally, we verified the availability of dVm/dt_{max_repol} for TdP risk prediction through the correlation analysis with qNet, the representative TdP metric. We performed the population simulations based on the methodology of Gemmel et al. using the human ventricular myocyte model of Dutta et al. Among the sixion channel conductances, dVm/dt_{max_repol} and qNet responded most sensitively to the change in g_Kr, followed by g_NaL. Furthermore, dVm/dt_{max_repol} showed a statistically significant high negative correlation with qNet. The dVm/dt_{max_repol} values were significantly different according to three TdP risk levels of high, intermediate, and low by qNet (p<0.001). In conclusion, we suggested dVm/dt_{max_repol} as a new biomarker metric for TdP risk assessment.

• Journal of Conservation Science
• /
• v.37 no.6
• /
• pp.778-790
• /
• 2021

The Stone Seated Buddha Triad and Stone Standing Buddha in Bijung-ri are state-designated heritage (treasure) statues having the Buddha style of the Goryeo dynasty from the 6th century. Conservation scientific investigations were conducted to understand the preservation status of these stone Buddha statues and to establish a conservation plan. The Stone Seated Buddha Triad and Stone Standing Buddha are composed of fine-medium grained biotite granite, which is considered to be of the same origin owing to their low magnetic susceptibility distribution of less than 0.2 (×10^-3 SI unit) and similar mineral characteristics. The Stone Seated Buddha Triad has highly homogenous mineral composition and particle size, whole-rock magnetic susceptibility, and geochemical characteristics very similar to those of the nearby outcrop. It was confirmed that a combination of physical, chemical, and biological factors affects the Stone Buddha statues. In particular, both the Stone Seated Buddha Triad and Stone Standing Buddha tend to be chipped off from the front and cracked and scaled from the back. The Stone Standing Buddha located outdoors experiences granularity decomposition and black algae formation, which accelerate the weathering under unfavorable conservation environments. The result of non-destructive physical property diagnosis using ultrasonic velocity showed that both the Stone Seated Buddha Triad and Stone Standing Buddha have been completely weathered (CW), indicating very poor physical properties.

• Journal of Biomedical Engineering Research
• /
• v.43 no.1
• /
• pp.52-60
• /
• 2022

Purpose: For now, cognitive load is assessed based on survey-based methods, which can be difficult to track the amount of cognitive load in real-time. In this study, we investigated the difference in electrophysiological activation due to different levels of cognitive load not only at sensor-level but also at source-level using electroencephalogram that might be potentially used for quantitative cognitive load evaluation. Materials and Methods: In this study, ten healthy subjects (mean age 24.3 ± 2.1, three female) participated the experiment. All participants performed 4 sessions of n-back task in different difficulties: 0-, 1-, 2-, and 3-back during electroencephalogram recording. For sensor-level analysis, we calculated the event-related potential and event-related spectral perturbation while low resolution brain electromagnetic tomography (LORETA) to estimate the source activation. Each result was compared between different workload conditions using statistical analysis. Results: Statistical results revealed that the accuracy of the task performance was significantly different between different cognitive loads (p = 0.018). The post-hoc analysis confirmed that the accuracy of the 3-back task was significantly decreased compared to 1-back condition (p = 0.018), but not with 2-back condition (p = 0.180). ERP results showed that P300 target amplitude between 1-back and 3-back had a marginal difference in Cz (p = 0.059) and Pz(p = 0.093). A significant inhibition in Cz high-beta activation (p = 0.017) and decrease in source activation of right parahippocampal gyrus was found in 3-back condition compared to 1-back condition (p < 0.05). Conclusion: In this study, we compared the sensor- and source-level differences in electroencephalogram between different levels of cognitive load, that were found to be in line with the previous reports related to cognitive load evaluation. We expect that the outcome of the current study can be used as a feature to establish a quantitative cognitive load assessment system.

• Journal of Nutrition and Health
• /
• v.55 no.4
• /
• pp.430-440
• /
• 2022

Selenium is an important trace mineral that plays an essential role in maintaining the body's immunity with oxidative stress defense and antioxidant activity, immunity, thyroid hormone control, defense against drug or heavy metal harm, and reducing the risk of chronic diseases. A selenium deficiency increases the risk of various chronic diseases, such as cancer, cardiovascular disease, diabetes, neurological disease, osteoarthritis, muscle necrosis and weakness, thyroid disease, and inflammatory diseases. This paper explains the criteria for establishing and revising selenium in the 2020 Dietary Reference Intake for Koreans (KDRIs) and reviews the current status of the selenium database and suggestions for setting the 2025 KDRIs in the future. In the 2020 KDRIs, the selenium intake with the maximum plasma selenoprotein P level was used as the criteria. The weight and coefficient of the variation were applied to the Chinese' reported values. Compared to 2015 KDRIs, there were some revisions in the selenium dietary reference intakes by gender and age according to the change in reference weight. To improve and revise selenium dietary reference intakes in the future, a selenium intervention study is needed to determine the maximum level of plasma selenoprotein P in Koreans. In addition, a revision of the selenium database of the nutritional assessment program (CAN-Pro 5.0) is needed. An analysis of the selenium content of foods should be expanded to assess the selenium intake accurately. In addition, research on the relationship between selenium intake and the biological indicators in the body is required for healthy people and subjects of special environments, such as patients and athletes with various oxidative stress.

• Restorative Dentistry and Endodontics
• /
• v.46 no.2
• /
• pp.21.1-21.12
• /
• 2021

Objectives: This study compared the cytotoxicity, biocompatibility, and tenascin immunolabeling of a new ready-to-use hydraulic sealer (Bio-C Sealer) with MTA-Fillapex and white MTA-Angelus. Materials and Methods: L929 fibroblasts were cultivated and exposed to undiluted and diluted material extracts. Polyethylene tubes with or without (the control) the materials were implanted into the dorsa of rats. At 7 days and 30 days, the rats were euthanized, and the specimens were prepared for analysis; inflammation and immunolabeling were measured, and statistical analysis was performed (p < 0.05). Results: MTA-Fillapex exhibited greater cytotoxicity than the other materials at all time points (p < 0.05). The undiluted Bio-C Sealer exhibited greater cytocompatibility at 6 and 48 hours than white MTA-Angelus, with higher cell viability than in the control (p < 0.05). White MTA-Angelus displayed higher cell viability than the control at 24 hours, and the one-half dilution displayed similar results at both 6 and 48 hours (p < 0.05). At 7 days and 30 days, the groups exhibited moderate inflammation with thick fibrous capsules and mild inflammation with thin fibrous capsules, respectively (p > 0.05). At 7 days, moderate to strong immunolabeling was observed (p > 0.05). After 30 days, the control and MTA-Fillapex groups exhibited strong immunolabeling, the white MTA-Angelus group exhibited moderate immunolabeling (p > 0.05), and the Bio-C Sealer group exhibited low-to-moderate immunolabeling, differing significantly from the control (p < 0.05). Conclusions: Bio-C Sealer and white MTA-Angelus exhibited greater cytocompatibility than MTA-Fillapex; all materials displayed adequate biocompatibility and induced tenascin immunolabeling.