• Journal of Environmental Science International
• /
• v.20 no.2
• /
• pp.241-249
• /
• 2011

In this research, equilibrium of adsorption and kinetics of As(V) removal were investigated. The coal mine drainage sludge(CMDS) was used as adsorbent. To find out the physical and chemical properties of CMDS, XRD (X-ray diffraction), XRF (X-ray fluorescence spectrometer) analysis were carried out. The CMDS was consist of 70% of goethite and 30% of calcite. From the results, an adsorption mechanism of As(V) with CMDS was dominated by iron oxides. Langmuir adsorption isotherm model was fitted well more than Freundlich isotherm adsorption model. Adsorption capacities of CMDS 1 was not different with CMDS 2 on aspect of amounts of arsenic adsorbed. The maximum adsorption amount of two CMDS were respectively 40.816, 39.682 mg/g. However, the kinetic of two CMDS was different. The kinetic was followed pseudo second order model than pseudo first order model. Concentrations of arsenic in all segments of the polymer in CMDS 2 does not have a constant value, but the rate was greater than the value of CMDS 1. Therefore, CMDS 2, which is containing polymer, is more effective for adsorbent to remove As(V).

• 한국경영정보학회:학술대회논문집
• /
• 2008.06a
• /
• pp.35-51
• /
• 2008

This study is to investigate factors that affect preference to CMDS(convergence mobile data service) on institutionalization of MDS. A research model was proposed and subsequent hypotheses were empirically tested with partial least square (PLS) based on 400 responses from the users of CMDS(DMB: 200 / m-Banking: 200). It was learned that institutionalization of technology related building MDS was positively associated with assimilation of MDS(represent a institutionalization of MDS) rather than service quality and use gratification. It means that users decided use of MDS refereed from its level of assimilation to MDS channel. Also, attractiveness of alternatives to CMDS is negatively associated with continuous use of CMDS and preference to CMDS. Lastly, their association strength was partially moderated by the type of motivation for using CMDS.

• Journal of Soil and Groundwater Environment
• /
• v.26 no.6
• /
• pp.18-26
• /
• 2021

Soil aggregation begins with flocculation of clay particles triggered by interfacial reactions of polyvalent cation such as Ca²⁺ and Fe³⁺, and they are also known as important elements to control the mobility of arsenic in soil environment. The objective of this study was to investigate the feasibility of CMDS (coal mine drainage sludge) for soil loss reduction and stabilization of arsenic-contaminated soil in a 37% sloped farmland under rainfall simulation. The amount of soil loss decreased by 43% when CMDS was applied, and this result was not significantly different from the case of limestone application, which yielded 46% decrease of soil loss. However, the relative amount of dispersed clay particles in the sediment CMDS-applied soil was 10% lower than that of limestone-applied soil, suggesting CMDS is more effective than limestone in inducing soil aggregation. The concentrations of bioavailable arsenic in CMDS amended soil decreased by 46%~78%, which was lower than the amount in limestone amended soil. Therefore, CMDS can be used as an effective amendment material to reduce soil loss and stabilize arsenic in sloped farmland areas.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.5
• /
• pp.713-714
• /
• 2005

• Journal of Soil and Groundwater Environment
• /
• v.25 no.1
• /
• pp.53-61
• /
• 2020

This study assessed the feasibility of coal mine drainage sludge (CMDS) as a stabilizing agent for mercury contaminated soil through pot experiments and batch tests. In the pot experiments with 43 days of lettuce growth, the bioavailability of mercury in the amended soil and mercury content of the lettuce were decreased by 46% and 50%, respectively. These results were similar to those of the soil amended with the sulfide compound (FeS) generally used for mercury stabilization. Thus, CMDS could be an attractive mercury stabilizer in terms of industrial by-product recycling. Batch tests were conducted to examine mercury fractionation including reactions between the soil and acetic acid. The result showed that some elemental fraction changed to strongly bounded fraction rather than residual (HgS) fraction. This made it possible to conclude that mercury adsorption on oxides in CMDS was the major mechanism of stabilization.

• Korean Journal of Soil Science and Fertilizer
• /
• v.41 no.5
• /
• pp.324-329
• /
• 2008

A coal mine drainage sludge(designated as CMDS) is mainly generated during physicochemical treatment or electrical purification of the drainage abandoned mine that include dissolved heavy metal. To understand the possibility of an application of the dehydrated CMDS as the landfill cover medium of hygienic a reclaimed ground, an laboratory experiment was performed to investigate the physicochemical and geoengineering characteristics of the dehydrated CMDS. To improve the geoengineering characteristics of the dehydrated CMDS, the liquid limit, plasticity limit test, compaction method test, strength test, and hydraulic conductivity test ware performed with the lithification material mixed sludge. When the mixed ratio of the sludge and the lithification material was more than 1:06, the compaction method was A method, the moisture content less than 33.5%, the strength of mixed sludge was $8.2kg\;cm^{-2}$, the hydraulic conductivity was $2.7\times10^{-6}cm\;sec^{-1}$, the sludge was up to the landfill standard of US Environmental Protection Agency (US EPA).

• Journal of Astronomy and Space Sciences
• /
• v.15 no.2
• /
• pp.277-289
• /
• 1998

We report V-(B - V) CCD Color Magnitude Diagrams (CMDs) for 23 southern Galactic globular clusters. Limiting magnitudes for each cluster are between 18 and 20 magnitudes in V. Most CMDs show subgiant starts, red giant stars, and horizontal branch stars. From the CMDs, we have determined the horizontal branch magnitudes, V(HB), reddenings, E(B - V), and distances of each cluster.

• Economic and Environmental Geology
• /
• v.56 no.2
• /
• pp.125-138
• /
• 2023

Most of previous cesium (Cs) sorbents have limitations on the treatment in the large-scale water system having low Cs concentration and high ion strength. In this study, the new Cs sorbent that is eco-friendly and has a high Cs removal efficiency was developed by improving the coal mine drainage treated sludge (hereafter 'CMDS') with the addition of Na and S. The sludge produced through the treatment process for the mine drainage originating from the abandoned coal mine was used as the primary material for developing the new Cs sorbent because of its high Ca and Fe contents. The CMDS was improved by adding Na and S during the heat treatment process (hereafter 'Na-S-CMDS' for the developed sorbent in this study). Laboratory experiments and the sorption model studies were performed to evaluate the Cs sorption capacity and to understand the Cs sorption mechanisms of the Na-S-CMDS. The physicochemical and mineralogical properties of the Na-S-CMDS were also investigated through various analyses, such as XRF, XRD, SEM/EDS, XPS, etc. From results of batch sorption experiments, the Na-S-CMDS showed the fast sorption rate (in equilibrium within few hours) and the very high Cs removal efficiency (> 90.0%) even at the low Cs concentration in solution (< 0.5 mg/L). The experimental results were well fitted to the Langmuir isotherm model, suggesting the mostly monolayer coverage sorption of the Cs on the Na-S-CMDS. The Cs sorption kinetic model studies supported that the Cs sorption tendency of the Na-S-CMDS was similar to the pseudo-second-order model curve and more complicated chemical sorption process could occur rather than the simple physical adsorption. Results of XRF and XRD analyses for the Na-S-CMDS after the Cs sorption showed that the Na content clearly decreased in the Na-S-CMDS and the erdite (NaFeS₂·2(H₂O)) was disappeared, suggesting that the active ion exchange between Na⁺ and Cs⁺ occurred on the Na-S-CMDS during the Cs sorption process. From results of the XPS analysis, the strong interaction between Cs and S in Na-S-CMDS was investigated and the high Cs sorption capacity was resulted from the binding between Cs and S (or S-complex). Results from this study supported that the Na-S-CMDS has an outstanding potential to remove the Cs from radioactive contaminated water systems such as seawater and groundwater, which have high ion strength but low Cs concentration.

• Journal of the Korean Geosynthetics Society
• /
• v.10 no.2
• /
• pp.67-72
• /
• 2011

CMDS (Coal Mine Drainage Sludge) is mainly generated from acid mine drainage during physicochemical treatment or electrical purification. CMDS is well worth considering on recycling possibilities in various areas. This research applies the liner and cover materials using waste disposal landfill generally to treat acid mine drainage sludge. In this Part I of the two parts paper, physico-chemical characteristics of CMDS, bentonite and cement to prepare the liner have been identified using XRD, XRF, FESEM. In addition, combining their physicochemical characteristics, the optimum mixing ratio has been determined to be 1: 0.5: 0.3 for CMDS: bentonite: cement by the batch tests. Initial permeability of CMDS was $7.10{\times}10^{-7}cm/s$. Through the leaching test, it was confirmed that its mixture was environmentally safe. In the Part 2, a large-scale Lysimeter was used to simulate the effects of the layer on the freeze/thaw for evaluation on field applicability and stability.

• Journal of Aerospace System Engineering
• /
• v.10 no.4
• /
• pp.84-89
• /
• 2016

Electronic Warfare (EW) is the mission area responsible to establish and maintain a favorable position in the electromagnetic domain. Testing and Evaluation of EW devices on modern military aircraft to pursue this critical mission area require the use of a wide range of techniques and analytical methods to assure users of the readiness of EW system to meet the challenge of a combat environment. This paper is intended as an introductory text dedicated to EW systems (especially RWR, CMDS) test and evaluation techniques and will serve experienced engineers and program managers, as well as novice engineers, as a concise reference for EW systems' test and evaluation processes and testing resources.