• Journal of Energy Engineering
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• v.24 no.3
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• pp.67-73
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• 2015

Almost base-loaded power plants such as flaming coal and nuclear energy require large-scale transmission facilities (LTFs) in order to send electricity to remote consumption areas. As well known, LTFs incur various social costs. However, a decentralized generation source such as integrated energy business (IEB)-based combined heat and power (CHP) plant is located in nearby electricity-consuming area, and thus it does not demand LTFs, providing the benefits from avoiding the damages caused by them. This study attempts to measure the benefits of avoiding the damages from the LTFs by the use of the contingent valuation (CV) method. To this end, a national survey of randomly chosen 1,000 households was implemented and the public's willingness to pay (WTP) for substituting consumption of electricity generated from flaming coal-fired power plant, currently a dominant generation source in Korea, with that produced from IEB-based CHP plant. The results show that the WTP for the substitution is estimated to be about 41.4 won per kWh. Considering that this value amounts to 33% of the average price of residential electricity in 2014, the external benefit of the IEB-based CHP as a decentralized generation appears to be large.

• Journal of Soil and Groundwater Environment
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• v.13 no.3
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• pp.52-58
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• 2008

Mn-impregnated activated carbon (Mn-AC) prepared at different conditions was applied in the treatment of synthetic wastewater containing both organic and inorganic contaminants. Phenol and As(III) was used as the representative organic and inorganic contaminants, respectively. After evaluation of the physicochemical characteristic and stability of Mn-AC, oxidation of As(III) as well as adsorption of phenol by activated carbon(AC) and Mn-AC were investigated in a batch reactor. To investigate the stability of Mn-AC, dissolution of Mn from each Mn-AC was measured pH ranging from 2 to 4. Although Mn-AC was unstable at a strong acidic condition, the dissoluted Mn was below 3 ppm at pH 4. XRD analysis of Mn-AC indicated that the mineral type of the impregnated manganese was $Mn_2O_3$. From the simultaneous treatment of As(III) and phenol by AC and Mn-AC, As(III) oxidation by Mn-AC was greater than that by AC at lower pH, while the reverse order was observed at higher pH. After impregnation of Mn onto AC, 13% decrease of the surface area was observed, causing 8% reduction of phenol removal. Considering removal properties of As(III) and phenol, Mn-AC could be applied in the simultaneous treatment of wastewater contaminated with multi-contaminants.

• Journal of Environmental Impact Assessment
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• v.32 no.3
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• pp.157-165
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• 2023

In Korea, a major contaminant of farmland soils in the vicinity of abandoned mines is arsenic, for which the general soil reclamation method is contaminated soil stabilization and cover the stabilized soil with clean soil at a thickness of 40 cm. In a previous pot experiment study we confirmed the feasibility of a lower thickness (20 cm) of covering soil for such reclamation in abandoned coal mines, where arsenic contamination levels are generally lower than in metal mines. In this subsequent study a field experiment including rice plant cultivation in field test plots was conducted. For over 4 months, the transfer of arsenic from the contaminated soil to the unpolished rice grains was reduced by 44% when a clean soil covering with a thickness of 20 cm was applied. The maximum decrease (56%) was shown when the stabilization process was performed before the covering. These results reveal a lower thickness of clean soil covering has a high feasibility and it can increase cost-efficiency in the reclamation of an abandoned coal mine.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.591-610
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• 2020

Concrete with activated carbon and titanium dioxide (TiO₂) has been used to reduce the particulate matter (PM) in underground structures (e.g., tunnels) due to the high performance of nitrogen oxides (NOx) abatement. Damage (e.g. crack, spalling, or detachment) can be caused by the environmental and ageing effects on the surface of the particulate matter reduction concrete, installed on the tunnel lining. Therefore, it is important to evaluate the existence of spalling on the concrete surface for maintaining performance of NOx reduction. In this study, a basic research was performed for feasibility of spalling evaluation using electrical resistivity characteristics. Given the test results, the electrical resistivity was decreased as the ratios of activated carbon (0~15%) and TiO₂ (0~25%) were increased for specimens. Under a dry condition, electrical resistivity of cement specimens, mixed with activated carbon and TiO₂, was decreased up to 2.3 times, compared with the normal cement specimen. In addition, under saturation conditions (degree of saturation: 85~98%), electrical resistivity of cement specimens with activated carbon, was decreased up to 3.5 times, compared with the normal cement specimen. Regardless of the condition (dry or saturated), the difference of electrical resistivity values shows the range of 2.3~2.8 times between the mixing specimen (with activated carbon (15%) and TiO₂ (25%)) and the normal cement specimen. This study can help to provide basic knowledge for spalling evaluation using the electrical resistivity on the surface of the particulate matter reduction concrete in tunnels.

• Environmental and Resource Economics Review
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• v.24 no.3
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• pp.573-605
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• 2015

This study proposed scenarios of tax reform regarding taxation on bituminous coal for power generation since July 2015 and July 2014, estimated its impact on SMP, settlement price, tax revenue from year 2015 to year 2029. These scenarios are compared with those of the standard scenario. To estimate them, the power system simulation was performed based on the government plan, such as demand supply program and the customized model to fit Korea's power system and operation. Imposing a tax on bituminous coal for power generation while maintaining tax neutrality reducing tax rate on LNG, the short-term SMP is lowered than the one of the standard scenario. Because the cost of nuclear power generation is still smaller than costs of other power generation, and the nuclear power generation rarely determines SMPs, the taxation impact on SMP is almost nonexistent. Thus it is difficult to slow down the electrification of energy consumption due to taxation of power plant bituminous coal in the short term, if SMP and settlement price is closely related. However, in the mid or long term, if the capacity of coal power plant is to be big enough, the taxation of power plant bituminous coal will increase SMP. Therefore, if the tax reform is made to impose on power plant bituminous coal in the short term, and if the tax rate on LNG is to be revised after implementing big enough new power plants using bituminous coal, the energy demand would be reduced by increasing electric charges through energy tax reform. Both imposing a tax on power plant bituminous coal and reducing tax rate on LNG increase settlement price, higher than the one of the standard scenario. In the mid or long term, the utilization of LNG complex power plants would be lower due to an expansion of generating plants, and thus, the tax rate on LNG would not affect on settlement price. Unlike to the impact on SMP, the taxation on nuclear power plants has increased settlement price due to the impact of settlement adjustment factor. The net impact of energy taxation will depend upon the level of offset between settlement price decrease by the expansion of energy supply and settlement price increase by imposing a tax on energy. Among taxable items, the tax on nuclear power plants will increase the most of additional tax revenue. Considering tax revenues in accordance with energy tax scenarios, the higher the tax rate on bituminous coal and nuclear power, the bigger the tax revenues.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.291-300
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• 2013

The potential mineral resources in North Korea are magnesite, limestone, coal, graphite, iron, gold, silver, lead, and zinc. North Korea is mainly exporting coal and iron to China(70%) and EU countries. Gold ore reserves(or resources) in North Korea are about 2,000 tons and annual production is 2 tons based on metal. Major gold mines are Sooan, Holdong, and Daeyoodong mines and six smelters are operating. Fe ore reserves (or resources) are 4.3 billion tons and annual production is about 5 million tons based on 63.5% Fe. Major iron mines are Moosan, Leewon, Eunryul, Shinwon, and Jaeryong and 7 smelters are operating. Pb and Zn ore reserves(or resources) are Pb 470,000 tons and Zn 15 million tons, and annual productions are about Pb 26,000 tons and Zn 50,000 tons based on metal respectively. Major Pb-Zn mines are Gumdock and Seongcheon mines. Magnesite ore reserves(or resources) are 2.8 billion tons (95% MgO) and annual production is about 150,000 tons. Major magnesite mines are Ryongyang, Daeheung Youth and Ssangryong mines, and 5 magnesium refractory factories are operating. Apatite ore reserves(or resources) are 340 million tons(30% $P_2O_5$) and annual production is about 300,000 tons(crude ore). Major apatite mines are Daedaeri, Dongam and Poongnyen mines. Coal is established as an important strategic fuel mineral resources and is a major energy source in North Korea. Coal ore reserves(or resources) are 18.6 billion tons and annual production is about 20 million tons. The main coal fields is located in southern Pyongan and the Jigdong mine is the biggest in North Korea.

• Journal of the Korean GEO-environmental Society
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• v.11 no.8
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• pp.25-32
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• 2010

Contamination of soil and groundwater by the compounds of hydrocarbon petroleum has been widely accepted as the main cause that harms the environments and health. To remove those pollutants, absorbing clothes, activated carbons, or oil-water separation devices with the gravity method are employed for treatment. However, those materials and devices cannot remove the emulsion pollutants despite of their efficiency for removing free products. Therefore, we investigated the problems which occur during the groundwater treatment for the highly concentrated suspended solid particles, which can be resulted from excavation, and to propose methods to remove TPH(Total Petroleum Hydrocarbon). After coagulation experiment with high molecular polymers, the concentration of SS(Suspended Solids) and COD(Chemical Oxygen Demand) turned to satisfy the groundwater quality criteria within 5 minutes while the concentration of TPH failed to meet the water quality standard of effluent. Consequently, the water quality criteria for effluent could not be met by single DAF(Dissolved Air Flotation) process. However all water quality criteria could be satisfied after 20 minutes when coagulation reactions are carried out simultaneously in the DAF reactor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.549-556
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• 2010

In general, materials that can be used to form elastic pads, such as urethane and rubber, are often used in flexible forming processes by inserting the pads between a blank and flexible die for smoothing the forming surface that is formed by a reconfigurable die. In this study, the effects of the elastic pad on formability in the flexible forming process for sheet metals are investigated by performing numerical simulations. In the simulation, the hyperelastic material model is used, where the urethane elastic pads serve as elastic cushions. Case studies are carried out for elastic materials with different hardness values and thicknesses. The results are used to evaluate formability by comparing the configuration of the deformed blank and its major cross-sectional profiles. It is verified that the elastic pad used in the flexible forming process for sheet materials should be hard and that its thickness should be chosen appropriately.

• Journal of Energy Engineering
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• v.19 no.3
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• pp.156-162
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• 2010

3-D CFD(Computational Fluid Dynamics) work were carried out to investigate the combustion characteristics in a boiler depending on the variations in air supply condition. For the gas temperature, $O_2$, NO, SOx at the outlet of economizer, the predicted values were been compared with the measured data. With the verified CFD model, the effects of air flow rates through SOFA(Separated Over Fire Air) and CCOFA(Closed Coupled Over Fire Air) on the combustion behavior in a boiler were simulated, and the distributions of NOx and gas temperature were mainly compared each other. The change in SOFA air flow rate gave the more sensitive effect on NOx than that in CCOFA. The distributions of gas temperature at convection path are differed with the changes in SOFA and CCOFA flow rate, so the combustion modification such as yaw anlge adjustment are required to get an enhanced gas temperature distribution.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.913-924
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• 1996

In this study HDS(hydrodesulfurization) of thiophene was researched over nickel catalysts added with small amounts of neodymium which were prepared by different methods such as unsupported coprepricipitated NdNi catalysts, unsupported intermetallic $NdNi_5$ catalysts, and carbon supported NdNi catalyst. The HDS activity was remarkably increased when a small amounts of neodymium was added to unsupported coprecipitated Ni catalysts. Thus it was known that the role of Nd is important in HDS of thiophene of Ni catalysts. For the case of unsupported intermetallic $NdNi_5$, the intermetallic crystallinity was destroyed to oxide and sulfide after calcination and presulfidation respectively. The HDS activity of thiophene can be explained by surface area of unsupported catalysts. And Nd acts like as structural promoter keeping the high surface area of unsupported catalysts. The HDS activity was increased by each ten times based on 1 gr. of nickel in the order of unsupported intermetallic $NdNi_5$, unsupported coprecipitated NdNi, and carbon supported NdNi catalysts according to different preparation method of catalysts.