• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.1
• /
• pp.83-89
• /
• 2000

Bentonite has been considered as a liner material to restrict the release of hazardous heavy metals from the landfill. The adsorption of copper onto a domestic bentonite was studied to provide the adsorption isotherm and the effect of solution chemistry and temperature. The copper adsorption was fitted well to a Freundlich isotherm, in which Freundlich constants and correlation coefficient were calculated to be $K_F=1.18$, n=1.65, and $r^2=0.97$, respectively. The distribution coefficients ($K_d$) for the adsorption of copper decreased with increasing initial copper concentration. The $K_d$ increased with increasing the pH of solution, and drastically increased at pH > 5.3 because of precipitation of most copper species. As the ion strength of $Na^+$ in solution increased the $K_d$ decreased, while it increased with increasing the concentration of $SO_4{^{2-}}$ in solution. An increase in the temperature of experimental solution decreased the $K_d$ values.

• Economic and Environmental Geology
• /
• v.41 no.4
• /
• pp.453-464
• /
• 2008

This study is to examine a relation between coal mining subsidence occurrence at abandoned underground coal mines and underground goaf with respect to surface geology, subsurface structure, depth and thickness of coal beds and the distribution of drifts. A study is carried out at the site where susceptibility of coal mining subsidence was proven high in a previous study. In that previous study, the susceptibility of coal mining subsidence was spatially analyzed by GIS using digitized geological maps, investigation reports, digitized mining tunnel maps without consideration of subsurface structure and the multi-level arrangement of drifts. Here we analyze geological characteristics around the goaf and the distribution of coal seam based upon digitized geological maps and investigation reports on the study area. And digitized mining tunnel maps are also used to analyze the depth and multi-level arrangement of drifts. The results show that weakened surface rock strength, relatively shallow depth and large thickness of coal seam below the surface are closely related to the coal mining subsidence occurrence. Complicatedly inter-connected drifts, shallow depth of drifts and surface rock fractures are revealed as additional control factors affecting coal mining subsidence. These factors examined in this study as well as original factors should be taken into account for the quantitative estimation of coal mining subsidence occurrence at abandoned underground coal mine.

• Journal of Biomedical Engineering Research
• /
• v.24 no.4
• /
• pp.355-361
• /
• 2003

In the present study, a new Real Time Subjective Evaluation (RTSSE) system was developed. The system is composed of two parts: a sensibility input part and sensibility evaluation part. The sensibility input part receives values, which are recorded on an input board using a stylus and digital tablet, from each subject's evaluation of his/her own subjective sensibility towards a particular stimulus. The sensibility evaluation part displays the level of pleasantness and arousal on one or two dimensions in real time. An experiment was conducted in order to investigate the feasibility and effectiveness of the RTSSE system. The present study compared Galvanic Skin Response (GSR) with the RTSSE by presenting 28 subjects in their 20s with pictures arousing either positive or negative sensibility. Following the experiment, an off-line subjective assessment using a questionnaire was given to the same subjects. According to the correlation coefficients, changes in subjective sensibility caused by the positive visual stimulus were related more closely to GSR, from the positive visual stimulus, and changes in subjective sensibility caused by the negative visual stimulus were related more closely to GSR from the negative visual stimulus. The questionnaire results showed marked similarity to the average responses of the RTSSE. In conclusion, the most remarkable characteristic of the present system is that it not only assesses the average sensibility when stimuli are presented, but also shows the changing strength of sensibility over time.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.4
• /
• pp.1165-1175
• /
• 2021

The purpose of this study was to analyze the correlation between pulmonary function, basic physical fitness (PF), and physical activity (PA), and to compare the differences by gender in Korean college students. Measurements of body composition, basic PF, PA (questionnaire), and pulmonary function tests of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) using a Quark pulmonary function test were carried out on 312 healthy participants (150 males [mean age: 19.29±1.72 years] and 162 females [mean age: 19.05±1.17 years]). The pulmonary function of male students was related to right-handedness, left-handedness, and back strength, and the pulmonary function of female students was related to all basic PF. The pulmonary function of male students was related to all PA variables, whereas the pulmonary function of female students was related to middle-intensity PA. The findings of this study suggest that male students need to increase PA, and female students need to improve basic PF to sustain a healthy pulmonary function. Understand gender differences for pulmonary function-related factors and the gender-specific educational efforts are needed to improve and maintain pulmonary capacity in college students.

• Journal of the Korean Geotechnical Society
• /
• v.37 no.10
• /
• pp.13-25
• /
• 2021

The most widely used method for determining the blast effects of explosives is the Trauzl test. This test is used to measure the explosive power (strength) of a substance by determining volume increase, which is produced by the detonation of a tested explosive charge in the cavity of a lead block with defined quality and size. In this paper, Trauzl lead block test and High speed 3D-DIC (Digital Image Correlation) system were conducted to evaluate the stemming effect of the blast hole. The effects of stemming materials can be expressed as the expansion of the cavity in a standard lead block through explosion of the explosives. The blasting experiment was conducted with emulsion explosives. The stemming material in the blast hole of lead block, which was adopted in this study, were using sand and stone chips. Results of blasting experiment and numerical analysis showed that the expansion rates of lead block were most affected by stone chips followed by sand. Also, as result of dynamic strain measurement on the lead block surface of High speed 3D-DIC system, the displacement and surface strain on the block were the highest in the experiment case of stone chips stemming.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.4
• /
• pp.514-520
• /
• 2021

In this study, EMP shielding performance was evaluated using electric furnace oxidized slag to give EMP shielding performance to concrete among the most used materials in construction sites. As a result of the evaluation, the component of the electric furnace oxidation slag was found to have an Fe₂O₃ content of 34%, and it was also found to contain an MgO component of about 4.8%. In addition, as a result of conducting an aggregate stability evaluation due to concerns about expansion due to MgO components, it is considered to be suitable for the KS standard. EMP shielding performance evaluation result showed that there was no correlation in EMP shielding performance according to compressive strength, and that general aggregates did not have EMP shielding. However, it was found that the aggregate using the furnace oxidized slag had excellent EMP shielding performance, and the shielding performance improved as the thickness increased. As a result of the durability evaluation, it was found that the EMP shielding concrete has the durability of abortion compared to the general concrete. Through this, it is thought that it will be good to improve the shielding rate if concrete is manufactured using electric furnace oxide slag when constructing EMP shielding structures in the future.

• 한국노년학
• /
• v.36 no.3
• /
• pp.727-749
• /
• 2016

This systematic review was performed to investigate relationship between sarcopenia and cognitive function among community-dwelling older adults. Studies which reported prevalence rates of sarcopenia in community-dwelling older adults, relationships between sarcopenia and cognitive dysfunction, or effective interventions in alleviated symptoms of sarcopenia were selected. Of 43 studies reviewed, prevalence rate of sarcopenia ranged from 2.5-42.4% in 25 studies, and 4 studies revealed a significantly positive correlation between sarcopenia and cognitive dysfunction. Among 12 randomized-control trials (RCTs), exercise intervention was used in 2 studies; nutrition intervention in 6; and 4 studies included both the exercise and nutrition interventions. All interventional studies reported positive effects on muscle mass, muscle strength, or physical function. However, only 6 studies met the high quality criteria of Risk of Bias, and there was no study which evaluated cognitive function as an outcome measure. Therefore, this study draws attention to the lack of high-quality RCTs and exclusion of cognitive function as an outcome measure in the research of sarcopenia. A comprehensive and sustained system including standardized sarcopenia screening, assessments of cognitive functioning, and evidence-based intervention programs is needed in order to prevent and manage sarcopenia amongst older adults in the community.

• Journal of Conservation Science
• /
• v.34 no.6
• /
• pp.493-502
• /
• 2018

Currently, the fabrication of a high-tin bronze spoon by traditional manufacturing techniques involves 10 steps in the bronze ware workshop. Hot forging has a major influence on manufacturing and involves two to three steps. The dendritic ${\alpha}$-phase in the microstructure of the high-tin bronze spoon is refined and finely dispersed through hot forging. In addition, twinning is observed in the ${\alpha}$-phase of the hammered part, and the ${\alpha}$-phase microstructure gradually transform from a polygon to a circular shape due to hammering. In this process, the adjacent ${\alpha}$-phases overlap with each other and remain combined after quenching. The microstructure with the overlapping is also observed in bronze artifacts, and this shows the correlation with technical system. The results of the experimental hot forging of Cu-22%Sn alloys show that the decrease in in the amount of the dendritic microstructure, which forms during casting, is in proportion to the number of processing steps and that the refined grain obtained by hammering contributes to the improvement in the strength of the material. From the hammering marks, which are observed on both the bronze artifact excavated from archaeological sites and on the high-tin bronze spoon produced in the traditional workshop, it is presumed that the knowledge regarding the unrecorded manufacturing system of bronze ware in ancient times has been passed down in a traditional way up to the system used currently.

• Science of Emotion and Sensibility
• /
• v.22 no.1
• /
• pp.35-44
• /
• 2019

Individuals with problematic hypersexual behavior (PHB) evince the inability to control sexual impulses and arousal. Previous studies have identified that these characteristics are related to structural and functional changes in the brain region responsible for inhibitory functions. However, very little research has been conducted on the functional connectivity of these brain areas during the resting state in individuals with PHB. Therefore, this study used functional magnetic resonance imaging devices with the intention of identifying the deficit of the functional connectivity in the executive control network in individuals with PHB during the resting state. Magnetic resonance imaging data were obtained for 16 individuals with PHB and 19 normal controls with similar demographic characteristics. The areas related to the executive control network (LECN, RECN) were selected as the region of interest, and the correlation coefficient with time series signals between these areas was measured to identify the functional connectivity. Between groups analysis was also used. The results revealed a significant difference in the strength of the functional connectivity of the executive control network between the two groups. In other words, decreased functional connectivity was found between the superior/middle frontal gyrus and the caudate, and between the superior/middle frontal gyrus and the superior parietal gyrus/angular gyrus in individuals with PHB. In addition, these functional Connectivities related to the severity of hypersexual behavior. The findings of this study suggest that the inability to control sexual impulses and arousal in individuals with PHB might be related to the reduced functional connectivity of executive control circuits.

• Korean Journal of Clinical Laboratory Science
• /
• v.51 no.3
• /
• pp.379-385
• /
• 2019

Osteoporosis is a disease that increases the risk of fractures by inducing a decrease in bone strength by the changes in hormones and a decrease in minerals. Recent reports have indicated that the long-term administration of Adefovir dipivoxil (ADV), which is used as a treatment for the hepatitis virus and AIDS, may have osteoporotic side effects. On the other hand, there are few studies on the cytopathic correlation of these causes. In this study, the biological relevance of ADV was evaluated using osteoblast hFOB1.19 and vascular endothelial cell HUVEC. First, the cells were treated with ADV at different concentrations, and DAPI and crystal violet staining were performed for morphological analysis of each cell and nucleus. A CCK-8 assay, real-time PCR, alkaline phosphatase (ALP) staining, and activity was performed to evaluate the drug effects on cell proliferation, gene expression, and osteoblast differentiation. As a result, ADV induced cell hypertrophy in hFOB1.19 cells and HUVEC cells. Furthermore, ADV not only inhibited cell proliferation and TGF-${\beta}$ expression but was also involved in osteoblast differentiation. Overall, these results provide basic data to help better understand the mechanism of ADV-induced osteoporosis and its clinical implications.