• Resources Recycling
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• v.15 no.3 s.71
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• pp.38-45
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• 2006

The thermal filter press dewatering(TFPD) technology to improve the dewaterability through increasing the inner vapor pressure, lowering the filtration viscosity and forming the porosity easily within cake as applying the heat at the sludge layer was developed in this study. The hot water with temperature of $95^{\circ}C$ and pressure of $1.2kg_f/cm^2$ was supplied to the heating plate equipped between filter plates with plate size of $470{\times}470mm$ and material of polypropylene. Sludge was dewaterd by supplying pressure of $5kg_f/cm^2$ and then by squeezing pressure of $15kg_f/cm^2$. As a results of estimating the characteristics of thermal dewatering to consider the initial water content and organic content to be influenced by a period of water shortage and rainwater, the dewatered cake water content was about 35 wt% and dewatering velocity was $4DSkg/m^2{\cdot}hr$ under the rainwater period, and the dewatered cake water content was about 50 wt% and dewatering velocity was $1.5DSkg/m^2{\cdot}hr$ in the case of sludge of water shortage season. These results was superior to the mechanical dewatering performance with water content of 70wt% and dewatering velocity of $0.9DSkg/m^2{\cdot}hr$. On the base of the results of TFPD, energy consumpted to deal with DS(Dry Solid) of 1kg was estimated by 300 kJ. It was analyzed that the energy consumption of TFPD was decreased about one third with comparison to the dryer system. Dewatering velocity of this technology was faster than the one of mechanical dewatering equipment and it was easier to product low water content cake. Therefore, this technology was recognized that dewaterability was predominant because of the fast of dewatering velocity and production of low water content cake, and also this known as economical efficiency was excellent because of low energy consumption in comparison with dryer.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.699-710
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• 2006

Batch scale experiments to investigate the efficiency of the solidification process for metal mine tailing treatment were performed. Portland and MSG (micro silica pouting) cements were used as solidifier and three kinds of mine tailings (located at Gishi, Daeryang, and Aujeon mine) were mixed with cements to paste solidified matrices. Single axis com-pressible strengths of solidified matrices were measured and their heavy metal extraction ratios were calculated to investigate the solidification efficiency of solidified matrices created in experiments. Solidified matrices ($5cm{\times}5cm{\times}5cm$) were molded from the paste of tailing and cements at various conditions such as different tailing/cement ratio, cement/water ratio, and different cement or tailing types. Compressible strengths of solidified matrices after 7, 14, and 28 day cementation were measured and their strengths ranged from 1 to $2kgf/mm^2$, which were higher than Korean limit of compressible strength for the inside wall of the isolated landfill facility ($0.21kgf/mm^2$). Heavy metal extractions from intact tailings and powdered matrices by using the weak acidic solution were performed. As concentration of extraction solution for the powdered solidified matrix (Portland cement + Gishi tailing at 1:1 w.t. ratio) decreased down to 9.7 mg/L, which was one fifth of As extraction concentration for intact Gishi tailings. Pb extraction concentration of the solidified matrix also decreased to lower than one fourth of intact tailing extraction concentration. Heavy metal extraction batch experiments by using various pH conditions of solution were also performed to investigate the solidification efficiency reducing heavy metal extraction rate from the solidified matrix. With pH 1 and 13 of solution, Zn and Pb concentration of solution were over the groundwater tolerance limit, but at pH $1{\sim}13$ of solution, heavy metal concentrations dramatically decreased and were lower than the groundwater tolerance limit. While the solidified matrix was immerged Into very acidic or basic solution (pH 1 and 13), pH of solution changed to $9{\sim}10$ because of the buffering effect of the matrix. It was suggested that the continuous extraction of heavy metals from the solidified matrix is limited even in the extremely high or low pH of contact water. Results of experiments suggested that the solidification process by using Portland and MSG cements has a great possibility to treat heavy metal contaminated mine tailing.

• Economic and Environmental Geology
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• v.45 no.6
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• pp.661-672
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• 2012

Lab scale experiments to investigate the dissolution reaction among supercritical $CO_2$-sandstone-groundwater by using sandstones from Gyeongsang basin were performed. High pressurized cell system (100 bar and $50^{\circ}C$) was designed to create supercritical $CO_2$ in the cell, simulating the sub-surface $CO_2$ storage site. The first-order dissolution coefficient ($k_d$) of the sandstone was calculated by measuring the change of the weight of thin section or the concentration of ions dissolved in groundwater at the reaction time intervals. For 30 days of the supercritical $CO_2$-sandstone-groundwater reaction, physical properties of sandstone cores in Gyeongsang basin were measured to investigate the effect of supercritical $CO_2$ on the sandstone. The weight change of sandstone cores was also measured to calculate the dissolution coefficient and the dissolution time of 1 g per unit area (1 $cm^2$) of each sandstone was quantitatively predicted. For the experiment using thin sections, mass of $Ca^{2+}$ and $Na^+$ dissolved in groundwater increased, suggesting that plagioclase and calcite of the sandstone would be significantly dissolved when it contacts with supercritical $CO_2$ and groundwater at $CO_2$ sequestration sites. 0.66% of the original thin sec-tion mass for the sandstone were dissolved after 30 days reaction. The average porosity for C sandstones was 8.183% and it increased to 8.789% after 30 days of the reaction. The average dry density, seismic velocity, and 1-D compression strength of sandstones decreased and these results were dependent on the porosity increase by the dissolution during the reaction. By using the first-order dissolution coefficient, the average time to dissolve 1 g of B and C sandstones per unit area (1 $cm^2$) was calculated as 1,532 years and 329 years, respectively. From results, it was investigated that the physical property change of sandstones at Gyeongsang basin would rapidly occur when the supercritical $CO_2$ was injected into $CO_2$ sequestration sites.

• Economic and Environmental Geology
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• v.50 no.2
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• pp.171-180
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• 2017

This study performed the analysis on the volcanic gases and hot spring waters from the Julong hot spring at Mt. Baekdu during the period from July 2015 to August 2016. Also, we confirmed the errors that $HCO_3{^-}$ concentrations of hot spring waters in the previous study (Lee et al. 2014) and tried to improve the problem. Dissolved $CO_2$ in hot spring waters was analyzed using gas chromatograph in Lee et al. (2014). Improving this, from 2015, we used TOC-IC to analysis dissolved $CO_2$. Also, we analyzed the $Na_2CO_3$ standard solutions of different concentrations using GC, and confirmed the correlation between the analytical concentrations and the real concentrations. However, because the analytical results of Julong hot spring water were in discord with the estimated values based on this correlation, we can't estimate the $HCO_3{^-}$ concentrations of 2014 samples. During the period of study, $CO_2/CH_4$ in volcanic gases are gradually decreased, and this can be interpreted in two different ways. The first interpretation is that the conditions inside the volcanic edifice are changing into more reduction conditions, and carbon in volcanic gases become more favorable to distribute into $CH_4$ or CO than $CO_2$. The second interpretation is that the interaction between volcanic gases and water becomes greater than past, and the concentrations of $CO_2$ which have much higher solubility in water decreased, relatively. In general, the effect of scrubbing of volcanic gas is strengthened during the quiet periods of volcanic activity rather than active periods. Meanwhile, the analysis of hot spring waters was done on the anion of acidic gases species, the major cation, and some trace elements (As, Cd, Re).

• Korean Journal of Plant Resources
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• v.19 no.2
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• pp.218-222
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• 2006

This experiment was conducted to investigate the effects of climatic factors varied due to the type of plastic house, cultural season and location in the house on the growth of cucumber plants grown by nutrient solution. There were two growing periods, summer culture and retarding culture, two types of plastic houses, 1-2W type house and post-less house. Air temperature, relative humidity and amount of solar radiation in the plastic houses were measured. Also, dry weight of leaves and stems, plant height, number of leaves per plant, leaf area per plant and fresh weight of fruits per plant were observed. Plant growth analysis were conducted and interrelationships between climatic factors and physiological characteristics were investigated. The results were as follows. There were no differences between the type of plastic houses in the average air temperature and average relative humidity in the plastic house, but amount of solar radiation in 1-2W type house was significantly higher than that of postless house. Daily cumulative solar radiation were highest in southwest side of 1-2W type house and northwest side of postless house. Plant height and number of leaves per plant were higher in summer culture than retarding culture, while leaf area per plant was higher in retarding culture than summer culture. Relative growth rate (RGR) showed highly significantly positive correlations with net assimilation rate (WAR) and leaf area ratio (LAR). Contribution of NAR to RGR was much higher than that of LAR. Crop growth rate (CGR) showed highly significantly positive correlations with leaf area index (LAI). It appeared that increase of LAI was important to increase productivity of cucumber. Average daily air temperature for the whole growing period showed highly significantly positive correlations with RGR and NAR. Furthermore, cumulative solar radiation for the whole growing period in retarded culture showed significantly positive correlation with RGR and NAR.

• Economic and Environmental Geology
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• v.40 no.2 s.183
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• pp.209-221
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• 2007

Numerical analysis was performed to investigate the effect of heavy metal contamination on neighboring environment in case a dam is constructed by using rockfill materials contaminated by heavy metals. The numerical simulation carried out in this research includes both subsurface flow and contaminant transport in the inside of the CFRD(Concrete Faced Rockfill Dam), using two commercial programs, SEEP2D and FEMWATER. The three representative cases of scenarios were chosen to consider a variety of cases occurring in a dam site; (1) Scenario 1 : no crack in the concrete face slab, (2) Scenario 2 : a crack In the upper part of face slab, and (3) Scenario 3 : a crack between plinth and face slab in the lower part of face slab. As a result of seepage analysis, the amount of seepage in scenario 2 was calculated as $14.31\sim14.924m^3/day$ per unit width, corresponding to the 1,000 times higher value than that in other scenarios. Also, in the simulation of contaminant transport by using FEMWATER, specified contaminant concentration of 13 ppb in main rockfill zone was set to consider continuous leakage from the rock materials. Through the analysis of contaminant transport, we found that elapsed times to take for the contaminant concentration of about 2 ppb to arrive at the end of a dam are as follows. Scenario 1 has the elapsed time of 55,000 years. In Scenario 2. it is 50 years. Finally, scenario 3 has 27,000 years. The rapid transport of the contaminant in scenario 2 was attributed to greater seepage flow by 500 times than other scenarios. Although, in case of upper crack in the face slab, it was identified that the contaminant might transport to the end of a dam within 100 years with about 2 ppb concentration, however, it happened that the contaminant was hardly transported out of the dam in other scenarios, which correspond to either no crack or a crack between plinth and face slab. In conclusion, the numerical analysis showed that the alternative usage of the contaminated sand and gravel as the dam embankment material can be one of the feasible methods with the assumption that the cracks in a face slab could be controlled adequately.

• Economic and Environmental Geology
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• v.48 no.1
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• pp.51-63
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• 2015

I produced a secular variation model of geomagnetic field by using the magnetic component data from four geomagnetic observatories located in Northeast Asia during the years between 1997 and 2011. The Earth's magnetic field varies with time and location due to the dynamics of fluid outer core and the magnetic observatories on the surface measure in time series. To adequately represent the magnetic field or secular variations of the Earth, a spatio-temporal model is required. In making a global model, satellite observations as well as limited observatory data are necessary to cover the regions and time intervals. However, you need a considerable work and time to process a huge amount of the dataset with complicated signal separation procedures. When you update the model, the same amount of chores is demanded. Besides, the global model might be affected by the measurement errors of each observatory that are biased and the processing errors in satellite data so that the accuracy of the model would be degraded. In this study, as considered these problems, I introduced a localized method in modeling secular variation of the Earth's magnetic field over Northeast Asia region. Secular variation data from three Japanese observatories and one Chinese observatory that are all in the INTERMAGNET are implemented in the model valid between 1997 to 2011 with the interval of 6 months. With the resulting model, I compared with the global model called CHAOS-4, which includes the main, secular variation and secular acceleration models between 1997 to 2013 by using the three satellites' databases and INTERMAGNET observatory data. Also, the geomagnetic 'jerk' which is known as a sudden change in the time derivatives of the main field of the Earth, was discussed from the localized secular acceleration coefficients derived from spline models.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.5
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• pp.14-28
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• 2017

Mt. Seunghak's Miscanthus sinensis community is not only a landscape resource in terms of cultural services within the Ecosystem Services but also a site that is visited by many mountaineers in autumn. As the current Miscanthus sinensis community has been experiencing a rapid decline due to Korean forest succession characteristics, ongoing artificial management is thought to be needed for landscape resource use. The purpose of this study was to determine growth environment characteristics and the cause of the rapid decline of the Miscanthus sinensis community in Mt. Seunghak, which is located inside a large city with a large scale and outstanding accessibility. As the Miscanthus sinensis community is the representative early vegetation that appears temporarily in dry, barren soil, the Miscanthus sinensis community in Korean forest succession tends to be unsustainable. As the current soil on Mt. Seunghak is inappropriately fertile for the Miscanthus sinensis community, other wetland woody plant communities are anticipated to succeed it. If Miscanthus sinensis community maintenance is needed for Miscanthus sinensis landscape scenery, various alternatives apart from overall Miscanthus sinensis community maintenance should be determined for cost-effective management. For example, while many byways toward the inside of the Miscanthus sinensis community have affected the Miscanthus sinensis community growth environment, the installation of wooden fences and ropes has been a control in approach. As a result of this positive effect, many byways toward the inside of Miscanthus sinensis community have been restored naturally. Through viewable range analysis, as good scenery sites on the observatory have a good viewable range on the main trail as well, if these scenery sites are intensively managed, effective Miscanthus sinensis ccommunity management will be done despite maintenance budget cutbacks. This study is expected to be used as a basic material regarding the alternatives for a sustained Miscanthus sinensis community and the possibility of cultivating other growth in poor soils of fallow fields and unused land.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.3
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• pp.213-220
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• 2014

This is the study to conduct the topographical analysis using the orthophotographic data from the waypoint flight using the UAV and constructed the system required for the automatic waypoint flight using the multicopter.. The results of the waypoint photographing are as follows. First, result of the waypoint flight over the area of 9.3ha, take time photogrammetry took 40 minutes in total. The multicopter have maintained the certain flight altitude and a constant speed that the accurate photographing was conducted over the waypoint determined by the ground station. Then, the effect of the photogrammetry was checked. Second, attached a digital camera to the multicopter which is lightweight and low in cost compared to the general photogrammetric unmanned airplane and then used it to check its mobility and economy. In addition, the matching of the photo data, and production of DEM and DXF files made it possible to analyze the topography. Third, produced the high resolution orthophoto(2cm) for the inside of the river and found out that the analysis is possible for the changes in vegetation and topography around the river. Fourth, It would be used for the more in-depth research on landscape analysis such as terrain analysis and visibility analysis. This method may be widely used to analyze the various terrains in cities and rivers. It can also be used for the landscape control such as cultural remains and tourist sites as well as the control of the cultural and historical resources such as the visibility analysis for the construction of DSM.

• Economic and Environmental Geology
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• v.49 no.5
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• pp.349-360
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• 2016

This study determined mineralogical characteristics and discussed the meaning of mineralogical changes of the lower Choseon Supergrouop in the Weondong area based on the field geological investigation and the drilling core description using X-ray diffraction (XRD) mineral quantification and Scanning Electron Microscopy (SEM) observation. 100 samples with depth were collected from the core (250 m long) at a site in the study area. Especially, to investigate the changes from the upper Daegi Formation to the lower Hwajeol Formation, the samples were collected closely with the interval of about 0.3 m at this section. All samples were made into power using mortar for XRD. Mineral quantitative analysis was executed using Relative Intensity Ratio (RIR) method with corundum as an internal standard phase. Calcite, $2M_1$ illite and quartz are main constituents in most of samples. Dolomite and siderite are significantly observed in the Sesong Formation. As the results of quantitative analysis for the major minerals, the upper Daegi Formation is dominated by calcite with over 80%. The Sesong Formation includes high percentage of dolomite and siderite with the intercalation of thin layers containing high calcite and $2M_1$ illite contents. Hwajeol Formation is characterized by the alternation between thin layers of $2M_1$ illite and quartz-dominated layer (IQDL) and calcite-dominated layer (CDL). IQDL is more frequent in the lower part, whereas CDL is more common in the upper part. The boundary between Daegi Formation and the Sesong Formation is distinct, whereas the boundary between the Sesong Formation and the Hwajeol Formation tends to be changed gradually in mineralogy. The result of SEM observation shows that quartz and $2M_1$ illite are detrital, and a significant amount of calcite also shows detrital form with some recrystallized one, indicating that the repeated influx of terrestrial materials had changed the mineralogy of the shallow sea depositional environment in the early Paleozoic era.