• Journal of the Mineralogical Society of Korea
• /
• v.15 no.3
• /
• pp.195-204
• /
• 2002

Mineralogy and the exposed surface area are two of the most important factors controlling dissolution and weathering rates of soils. The mixture of inorganic and organic materials of various size distributions and structures that constitute soils makes the calculation of weathering rates difficult. The surface area of soil minerals plays an important role in most of programs for calculating the weathering rates and critical loads. The Brunauer-Emmett-Teller (BET) measurement is recommended for the measurement of specific surface area. However, BET values measured without organic matter removal are in fact those far all the N2-adsorbed surface areas, including the surfaces covered and aggregated with organisms. Surfaces occupied by organisms are assumed to be more reactive to weathering by organic activities. Therefore, the BET surface area difference before and after organic removal depicts the area occupied by organisms. The present study shows that the BET values after organic matter removal using $H_2$O$_2$ are larger than those without removal by 1.68~4.87 $m^2$/g. This implies that BET measurement without organic removal excludes the reactive area occupied by organisms and that the area occupied by organisms in soils is much larger than expected. It is suggested that specific surface area measurement for calculating weathering rates of mineral soils should be made before and after organic matter removal. The results of a column experiment are presented to demonstrate the potential retarding influence that this organic matter may have on mineral dissolution and weathering.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.5 no.1
• /
• pp.71-88
• /
• 2003

The DRASTIC system is widely used for assessing regional groundwater pollution susceptibility by using hydrogeological factors such as depth to water, net recharge, aquifer media, soil media, topography, vadose zone media, hydraulic conductivity. This study is providing Modified Drastic Model to which lineament density, land use, influence of groundwater drawdown caused by tunnel excavation are added as additional factors using geographic information system, and then to evaluate groundwater contamination potential of ${\bigcirc}{\bigcirc}$ area. For statistical analysis, vector coverage per each factor is converted to grid layer and after each correlation coefficient between factors, covariance, variance, eigenvalue and eigenvector by principal component analysis of 3 direction, are calculated, correlation between factors is analyzed. Also after correlation coefficients between general DRASTIC layer and rated lineament density layer, between general DRASTIC layer and rated land use layer, between general DRASTIC layer and rated tunnel excavation influence layer are calculated, final modified DRASTIC model is constructed by using them with each weighting. When modified DRASTIC model was compared with general DRASTIC model, contamination potential in modified DRASTIC model is fairly detailed and consequently, vulnerable area which has high contamination potential could be presented concretly.

• Economic and Environmental Geology
• /
• v.20 no.3
• /
• pp.159-168
• /
• 1987

Some physico-chemical properties such as surface area, moisture content, cation exchange capacity, swelling rate, pH, viscosity and liquid limit have been determined for evaluation of Cabentonite deposit occurring in four localities; Yonil, Gampo, Haseo and Pohang, in Gyeongsang-do. Montmorillonite contents can be derived from surface area measurement. Enhancement of liquid limit values and swelling volume were observed in the samples which had higher exchangeable Na ion and finer particle-size distribution. Identical results were observed even in the Na-exchanged samples. This suggests that aggregation effects have a great influence on physico-chemical properties. Aggregation of montmorillonite were controlled not only burial depth but also composition of exchangeable cation. Consequently, sample occurred in Yonil area where has the greatest burial depth in the area show somewhat lower physico-chemical properties than those of samples occurred in the other localities. However, the basic test applied in this study provides very useful preliminary information relating to its commercial potential.

• Annals of Clinical Neurophysiology
• /
• v.8 no.2
• /
• pp.125-134
• /
• 2006

Among the various physiological factors that affect nerve conduction velocity (NCV), temperature is the most important. Because the influence of temperature is the most important source of error. It is known from animal experiments that conduction is eventually completely blocked at low temperatures, the myelinated A fibers being the first affected and the thin fibers of group C the last. Many studies showed that the NCV decreases linearly with lowering temperature within the physiological range. The distal motor latency increased by $0.2msec/^{\circ}C$ drop in temperature between $25^{\circ}C$and $35^{\circ}C$ in the median, ulnar and peroneal nerves. The temperature affect the neuromuscular transmission; The miniature endplate potential (MEPP) and endplate potential (EPP) are increase with increasing temperature. In myasthenia gravis, the reduction in the decremental response is observed following cooling. The lowering temperature make increase the amplitude of sensory compound action potential; make enlarge the surface area of compound muscle action potential with very little increase in amplitude; make diminish the fibrillation potential and increase the myotonia in needle electromyography (EMG). Because of these findings mentioned above, the skin temperature should be routinely monitored and controlled during nerve conduction tests and needle EMG and should be taken into account when interpreting the findings.

• Asian Journal of Atmospheric Environment
• /
• v.8 no.3
• /
• pp.126-139
• /
• 2014

In order to estimate the influence of sources on $PM_{2.5}$ in the industrial area of Japan, we carried out a source analysis using chemical component data of $PM_{2.5}$. $PM_{2.5}$ samples were collected intermittently at an industrial area in Japan from July 2010 to November 2012. Water soluble ions ($Cl^-$, $NO_3{^-}$, $SO{_4}^{2-}$, $Na^+$,$NH_4{^+}$, $K^+$, $Mg^{2+}$, $Ca^{2+}$), elements (Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Sb, Pb), and carbonaceous species (OC, EC) of the $PM_{2.5}$ (a total of 198 samples) were analyzed. Positive Matrix Factorization (PMF) model was applied to the data of those chemical components to identify the source of $PM_{2.5}$. At this observation site, nine factors were extracted. The major contributors of $PM_{2.5}$ were secondary sulfate 1, in which loading factors of $SO{_4}^{2-}$ and $NH_4{^+}$ were large (percentage source contribution: 20.9%), traffic, in which loading factors of OC (organic carbon) and EC (elemental carbon) were large (20.8%), secondary sulfate 2, in which loading factors of K and $SO{_4}^{2-}$ were large (8.0%), steel mills (7.8%), secondary chloride and nitrate (7.0%), soil (5.0%), heavy oil combustion (3.8%), sea salt (3.8%), and coal combustion (2.3%). The conditional probability function (CPF) and the potential source contribution function (PSCF) were carried out to examine the influence of a regional source and a broad-based source, respectively. CPF results supported local source influences such as steel mills, sea salt, traffic, coal combustion, and heavy oil combustion. PSCF results suggested that ships in the East China Sea, an industrial area of the east coastal region of China, and an active volcano in the Kyushu region of Japan were potential regional sources of secondary sulfate 1. Secondary sulfate 2 was affected by the burning of biomass fields and by coal combustion in Chinese urban areas such as Beijing, Hebei, and western Inner Mongolia. Source characterization using continuous data from one site showed a potential source representing fossil fuel combustion is affected both by regional and broad-based sources.

• Journal of Environmental Science International
• /
• v.26 no.2
• /
• pp.211-220
• /
• 2017

For areas with the diverse contamination sources, the change of 4-nitrophenol contamination and impact of potential contamination sources have been evaluated using monitoring data and a numerical model (HydroGeoSphere). The model considered several parameters including land cover, precipitation, and flow rate. And, the model has been performed to investigate the effect of decay rate of 4-nitrophenol. The results of the simulations showed that the influence on 4-nitrophenol in downstream was mainly greater than that in upstream, and the tributaries did not significantly affect the mainstream because of their low flow rates. In addition, the effect of contamination sources was simulated for each section, then the measured data were higher than the corresponding simulated data in most sections of the Geumho river. In particular, the impact of the potential contamination sources in the upstream area was much higher than that in the other area, thus more monitoring data for the upstream area is required.

• Asia-Pacific Journal of Business
• /
• v.14 no.4
• /
• pp.129-150
• /
• 2023

Purpose - This study is based on the Theory of Planned Behavior and aims to explore the decision-making mechanisms of consumers participating in value co-creation activities within virtual brand communities. Methodology - The research involved a comprehensive survey of 405 participants from various virtual brand communities. Structural Equation Modeling (SEM) was used for data analysis, applying SPSS and AMOS to test the hypotheses. The study focused on community rules and regulations, community experience and community trust. Results - The research found that community rules and regulations significantly impact subjective norms and perceived behavioral control, but not directly influence consumer attitudes. Community experience positively affected consumer attitudes, subjective norms and perceived behavioral control. Community trust was found to positively influence these aspects of consumer decision-making. However, a gap was identified in the direct influence of perceived behavioral control on actual consumer behavior. Implications - The findings of this study contribute to a more comprehensive understanding of factors affecting consumer behavior in virtual brand communities. It underscores the necessity for community managers to develop strategies that consider these internal decision-making mechanisms, facilitating more effective community engagement. The study also identifies a potential area for future research in the direct influence of perceived behavioral control on actual consumer behavior.

• Journal of Korean Society of Rural Planning
• /
• v.11 no.2 s.27
• /
• pp.9-19
• /
• 2005

The purpose of this study is to analyze the potential soil loss and hazard zone by the Revised Universal Soil Loss Equation(RUSLE) for preservation and management of land resources which is the base of ecosystem, and to grasp the relationship between RUSLE factors in the Nakdong River Basin. All thematic maps used in RUSLE are constructed through GIS and spatial analysis method derived from digital topographic maps, detailed soil maps, land-cover maps, and mean annual precipitation of 30 years collected respectively from National Geographic Information Institute, National Institute of Agricultural Science and Technology, and Ministry of Environment. The slope length of LS-factor that takes much times by the study area's wideness was calculated automatically through AML(Arc Macro Language) program developed by Van Remortel et al.(2001, 2003). The results are as follows; First, according to the soil loss estimation by the RUSLE, it shows that approximately 82% of the study area have relatively lower possibility of soil loss which is the 1 ton/ha in annual soil loss. While, 9.4% ($2,228km^2$) needed intensive and continuous management for soil loss. Because the amount of their annual soil loss was greater than 10 ton/ha that is optimum level suggested by Morgan(1995). For these areas, the author believe that a new approach which can minimize environmental impacts from soil loss through improvement of cultivation process and buffer forest zone should be applied. Second, according to the relationship between the RUSLE factors, topographical(LS-factor) and cover management(C-factor) conditions have a lot of influence on soil loss in case of the Nakdong River Basin. However, because of RUSLE factor's influence that affect to soil loss might be different based on the variety of spatial hierarchy and extent, it is necessary to analyze and evaluate factor's relationship in terms of spatial hierarchy and extent through field observations and further studies.

• Journal of the Korean institute of surface engineering
• /
• v.49 no.2
• /
• pp.172-177
• /
• 2016

In this paper, various electrochemical experiments were conducted in seawater solution to evaluate corrosion damage behavior of arc thermal sprayed Inconel 625 coating on SS400 steel in marine environment. As a result, corrosion damages of thermal sprayed Inconel 625 coating preferentially occurred at the defect area, and they were observed as a form of pitting corrosion in the galvanostatic experiments. In Tafel analysis, corrosion current density of Inconel 625 coating was relatively high due to influence of interconnected pores and Cr oxides in the thermal spray coating layer. On the other hand, the result of the potential measurement, thermal sprayed Inconel 625 coating should need the post-treatment which can compensate the defects like pores and cracks because Inconel 625 coating presented a higher potential of about 290 mV than that of the SS400 steel.

• Advances in Energy Research
• /
• v.4 no.3
• /
• pp.203-211
• /
• 2016

A good understanding of the chemical composition and structural characteristics of a carbonaceous material is essential in conversion processes. Understanding how the composition and structural changes influence the burning behaviour of coal is important when assessing a coal's potential for utilization. To explore the potentials of a typical Nigerian coal, both conventional and advanced analytical techniques such as proximate analysis, ultimate analysis, calorific value, surface area analyser, SEM, FTIR, XRD and SAXS were employed. The results obtained from these characterizations agree favourable well with a typical South African coal that is of enormous contribution to the gross domestic product (GDP) of the nation economy.