• Resources Recycling
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• v.14 no.2
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• pp.19-27
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• 2005

The recycling possibility of aluminum waste dross(AWD) as a ceramic raw material of porous light-weight material was examined. A aluminum waste dross was washed 4-7 consecutive times and roasted at 900$^{\circ}% for 1hour as pre-treatments. The properties of the pre-treatment of aluminum waste dross was investigated. It was conformed by XRD result that the spinel crystalline was grown in AWD, after roasting. After the roasted AWD was ground in aqueous state, the sodium hexaphosphate(SHP) as a dispersant which is used for stabilizing the concentrated slurry was added to the AWD slurry. The porous material was prepared by slurry foaming method with surfactant at room temperature. The foamed slurry volumes were 2 and 3 times of the original slurry volume. The properties of porous material with extended volume of 3 times was following: the porosity was about 84%, bulk density was 0.59 g/cm$^3$, the range of pore was from 50 ${\mu}m$ to 500 ${\mu}m$ and mean pore size was about 200 ${\mu}m$. AWD porous material was sintered at 1150$^{\circ}C-1250$^{\circ}C. It was colcluded that AWD was sintered well at 1200$^{\circ}C from material surface observation by SEM.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.1
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• pp.112-130
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• 2006

In order to improve the waste management system for the unit of small villages, we visited 14 counties nationwide and investigated the present conditions of the farming and fishing villages on waste management. First, we selected one concentrated residential type village and one separated residential type village. Then we investigated the quantities and the characteristics of the domestic wastes generated from the 2 sample villages that we chose early on. The concentration of 7 heavy metals in open burned residuals was analyzed. The results are as follows: (1) We distributed the 799 questionnaires to public servants (83 Gun, 716 Myon) and 337 questionnaires to residents. In accordance with a result of questionnaire on the Volume-Based Waste Fee System, the rate of participated questionnaire was 70.3% from public servants and 31.8% from residents. (2) From the survey on two chosen villages, the generation of municipal waste was 48.6g/person/day in A Village, 54.3g/person/day in B Village. This amount was smaller than that of national average of 1.05kg because of excluding recyclable wastes and some of incinerated combustible waste. (3) The 14 counties entered the aged society. There were 2 aging societies, 8 aged societies and 4 super-aged societies. And the average ratios of Public financial independence and waste budget of financial independence were 16.1% and 17.9% respectively. These are lower than that of national average of 57.2% and 31.4%. This indicates that these factors seemed to be operated with the hindrance insettling Volume-Based Waste Fee System in the small villages.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.3
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• pp.47-54
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• 2018

This study examined the improvement of anaerobic digestion rate and sludge reduction as a result of the addition of anaerobic digestion with thickened sludge and solution of VFAs obtained from food waste. The methane production rate of the digestion system was 2.21 times higher when anaerobic digestion reactor injected into anaerobes with VFAs from food wastes of 5 percent. Also, The reduction of the amount of concentrated sludge injected will proceed rapidly because of the TCOD concentration in the digestion reactor was more than twice higher. Indirectly it was shown that the increased production system contributed significantly to the methane production efficiency.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.4
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• pp.371-375
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• 1988

Tubular ultrafiltration membranes were used to investigated mass transfer characteristics of waste cheese whey. The effects of bulk concentration and flow velocity on permeat flux, mass transfer coefficient and apparent rejection coefficient were measured. Mass transfer coefficient was increased linearly with increasing flow velocity, and following relationship between mass transfer coefficient(k) and linear velocity(u) was obtained. $k=0.87{\times}10^{-5}u^{1-1}$ It is interjecting to note that plots for all linear velocity tend to converge to the same point for zero permeating flux, and the maximum bulk concentration that can be achieved with cheese whey extracts was 38(w/v %). In general, membrane rejection coefficient increased with increasing flow velocity and the rejection coefficients of cheese whey solution and that of lactose in cheese whey solution were obtained $0.40{\sim}0.65$, $0.15{\sim}0.30$, respectively.

• Resources Recycling
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• v.23 no.5
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• pp.21-27
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• 2014

A study on the solvent extraction for the recovery of Li from lithium-containing waste solution was investigated using $D_2EHPA$ as an extractant. The experimental parameters, such as the pH of the aqueous solution, concentration of extractant and phase ratio were observed. Experimental results showed that the extraction percentage of Li was increased with increasing the equilibrium pH. More than 50% of Li was extracted in eq. pH 6.0 by 20% $D_2EHPA$. From the analysis of McCabe-Thiele diagram, 95% of Li was extracted by four extraction stage at phase ratio(O/A) of 3.0. Stripping of Li from the loaded organic phases can be accomplished by sulfuric acid as a stripping reagent and 90 ~ 120 g/L of $H_2SO_4$ was effective for the stripping of Li. Finially, Li was concentrated about 11.85 g/L by continuous stripping process, and then lithium carbonate was prepared by precipitation method.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.125-130
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• 2012

In these days, there has been increased focus on global warming and the exhaustion of resources recently caused by the heavy consumption of fossil resources. In order to resolve these problems, biomass is increasingly gaining international attention as a renewable energy source. Biogas derived from various biomass is environmental friendly alternative fuel for power generation, heating and vehicle fuel. Large amounts of sewage sludge, food waste and manure are generated from human activity, but these organic wastes contain high levels of organic matter and thus they are potential substrates for producing methane of biogas. The biogas contains 60% of highly concentrated methane, which is expected to be used effectively as energy. In this paper, we investigate the status of biogas in Korea as an alternative energy.

• Journal of the Korean GEO-environmental Society
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• v.18 no.9
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• pp.5-9
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• 2017

On the flow of groundwater, the effect of consecutive column-wall in underground as a hydraulic barrier could be identified by conventional geotechnical methods ((1)visualiy identification of wall mass after underground excavating, (2)uniaxial compressive strength test for core of wall mass in underground, (3)in-situ permeability test in the hole after coring wall mass). However, for the cut off the leakage or infiltration of very high concentrated leachate from the waste landfill or the contaminated groundwater, the waterproof effect of consecutive column-wall in underground should be verified more objectively, by in-situ measuring of pH, temperature and salinity. and by evaluating of their consistency and similarity throughout analyzing the characteristics of basic components and their profiles through the series of chemical experiments. Furthermore, its waterproof effect could be verified additionally throughout deciding the similarity more simply by comparing the general distribution patterns including the difference of high and low peaks from the chromatograms using GC-MS for surrounding groundwater.

• Resources Recycling
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• v.28 no.3
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• pp.53-58
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• 2019

Pb dross has been generated from recycling processes of waste acid lead batteries, and proper treatment of Pb dross was required because it contains As component, which has been found to be toxic. This study is aimed at concentrating As component by magnetic separation of ground product obtained from ball and mixer milling of Pb dross. No arsenic component was detected in the non-magnetic product of 10000 G magnetic separation using ground product with $-150{\mu}m$ by ball milling, and As could be concentrated upto 18.87 % by further 2000 G magnetic separation. The ball mill ground product with over $300{\mu}m$ was ground again by mixer mill to less than $150{\mu}m$, and then magnetic-separated by 4000 G followed by 2000 G magnet. The As component was concentrated upto 21.021 % in the magnetic fraction of 2000 G. It was confirmed that As component exsit as $Fe_2As$ by XRD measrument. These results indicate that As component could be concentrated from 0.6 % in the Pb dross to 21.021 % in the magnetic fraction by milling followed by magnetic separation.

• The Journal of Engineering Geology
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• v.28 no.3
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• pp.411-429
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• 2018

Daeyoung mine (also called "Daema mine") produced gold and silver from mainly gold- and silver-bearing quartz veins. The mine tailings are a waste hazard, but most of the tailings were swept away or dispersed throughout the area around the mine long before the tailing dump areas were transformed into agricultural land. Soil liner and protection facilities, such as retaining walls, were constructed in the mine area to prevent the loss of tailings. The content of the tailings is 3,424.41~3,803.61 mg/kg, which exceeds the safety standard by a factor of 45. In addition, contamination was detected near agricultural areas and in the sediments in downstream drainage channels. A high level of As contamination was concentrated near the waste tailings yard; comparaable levels were detected in agricultural areas close to streams that ran through the waste dump yard, whereas the levels were much lower in areas far from the streams. The contamination in stream sediments showed a gradual decrease with distance from the mine waste yard. Based on these contamination patterns, we concluded that there are two main paths that affect the spread of contaminants: (1) loss of mine waste, and (2) the introduction of mine waste into agricultural areas by floods after transportation by streams. The agricultural areas contaminated by mass inflow of mine waste can act as contamination sources themselves, affecting other agricultural areas through the diffusion of contaminants. At present, although the measured effect in minimal, sediments in streams are contaminated by exposed mine waste and surface liners. It is possible for contaminants to diffuse or spread into nearby areas if heavy elements trapped in soil grains in contaminated agricultural areas leach out as soil solution or contaminant particles during diffusion into the water supply.

• Korean System Dynamics Review
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• v.17 no.1
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• pp.5-24
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• 2016

This study structurally analyzes major inefficiency of Korea's healthcare delivery system by utilizing the systems thinking. In particular, the phenomenon of patient's concentrated visits to large hospitals, waste of resource due to competitions between clinics and large hopitals, and the structure of oversupply were visualized using the causal loop diagram. The inefficient structure of healthcare delivery system can be understood more clearly by utilizing the major system archetypes of 'success to the successful', 'tragedy of commons', 'escalation' and 'limits to growth'. This study also finds solution from archetypal structure suggested by Wolstenholme. The inefficient status of healthcare delivery system might be explained by the 'out of control' archetype. In conclusion, the public resources such as the national health insurance need to be acknowledged as the entire achievement. All the participants should cooperate with each other in order to improve the inefficiency of the healthcare delivery system. In addition, the arrangement of incentive system for cooperation, acceleration of health information technology, and development of innovative business models make the sustainable healthcare delivery system.