• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.660-667
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• 2018

This study examined the optimal manufacturing conditions of RDF using heat-dried sludge from sewage treatment plant in Cheonan with the oil-drying method. The amounts of oil evaporation and oil drying of the heat-dried sludge were measured at different temperatures to evaluate the value of the product. The performance of the product was then measured using a calorimeter and TGA. In addition, the concentration of odor, NH3, H2S, and TVOC during drying was determined using a portable odor-meter. Ingredient analysis was performed by EDS. Considering mass-production, the oil to heat-dried sludge weight ratio was fixed to 4:1. At $130^{\circ}C$, only physical mixing occurred after the instantaneous drying of internal water. Considering the eco-friendly aspects, there was no significant difference in the drying efficiency between $160^{\circ}C$ and $190^{\circ}C$. Therefore, the optimal conditions were a drying temperature of $160^{\circ}C$ within 5 minutes. Finally, the RDF manufactured in this study and fuel used in the thermal power plants were compared. The calorific value was 4,449kcal/kg, the water content was 2% and the ash content was 34%, which is higher than the fuel of thermal power plants. Therefore, it is believed that coal energy as well as wood pellets can be replaced.

• Journal of Energy Engineering
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• v.25 no.3
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• pp.1-8
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• 2016

North Korea is currently undergoing an economic crisis of industrial productivity reduction, which resulted from decreased energy production and economic sanctions due to conflicts with the international society. This paper examined the technological status of North Korea's natural gas and coal industries which are essential sectors for recovery of the economy and North-South cooperation on energy industry. This paper also analyzed investment strategies in North Korean energy industries and calculated the size of economic ripple effect of the investment on North and South Korea. In order to analyze the effect of the investment on North Korean economy, we constructed an inter-industry relation table of North Korea for year 2014 and used an input-output model. The ripple effect of the investment in natural gas and coal industries turned out to be 1.012 billion dollars and 2.742 billion dollars respectively. In order to analyze the ripple effect of the investment on South Korean economy, we constructed an inter-industry relation table of South Korea for year 2013 and used a demand-driven model for inter-industry analysis. As a result, production, added-value and employment inducement coefficients of the investment were calculated as 2.02073, 0.62697 and 8.99409 for the natural gas industry and 2.02130, 0.62701 and 9.00413 for the coal industry respectively.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.7-14
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• 2016

The economic crisis in North Korea has reduced its capacity to invest in the energy industries. The country is going through a vicious cycle of decreased investment in the energy industries and reduced energy production. This suggests that the energy industries would come to the top priority of investment once the economy improves. This paper calculated the economic ripple effect of the investment on North and South Korean economies based on the assumption that 390 billion won was invested in the construction of a natural gas combined-cycle power plant in Gaesong Industrial Complex. In order to analyze the economic ripple effect of the investment on North Korean economy, we constructed the inter-industry relation table of North Korea for year 2014 and used the input-output model. The ripple effect of the investment in the natural gas industry turned out to be 1.012 billion dollars. In order to analyze the effect of the investment on South Korean economy, we constructed the inter-industry relation table of South Korea for year 2013 and used the demand-driven model for inter-industry analysis. As a result, production, added-value and employment inducement coefficients of the investment in the natural gas industry were calculated as 2.02073, 0.62697 and 8.99409 respectively.

• Journal of the Korean GEO-environmental Society
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• v.11 no.7
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• pp.57-63
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• 2010

The necessity of effective and economical improvement for soft ground is required more and more as mountains form 70% of country. The soft ground improvement methods for ocean development are sand compaction pile method, displacement method are applied to the soft ground improvement from ocean development pre-loading method, air pressure method, well point method, pack drain method, quicklime pile method etc. Among them, the sand compaction pile method, has many problems such as the economical problem on importing materials due to the lack of sand and destroying the nature while collecting sand. To replace the sand with other alternative materials, a study on the bottom ash compaction pile method because the bottom ash has the similar engineering properties with sand. Therefore, in this study, after compose the complex soil with a replacement rate of 10~80% and a large direct shear test, shear test, consolidation test with replacement rates of bottom ash are performed to estimate whether its shear and consolidation characteristics are suitable for the alternative material of compaction pile method. As a result of test, Shear Strength Parameters tend to be increased in accordance with the increase of replacement ratio of bottom compaction pile, and Settlement Reduction Factor and $t_{90}$ tend to be decreased.

• Journal of the Korean GEO-environmental Society
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• v.13 no.3
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• pp.53-58
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• 2012

In general, sand compaction pile(SCP) method and gravel compaction pile(GCP) method have been mainly used to reinforce soft soils such as soft clay or loose sandy ground. But the sand compaction pile method has problems such as lack of sand supply and destroying the nature while collecting sand, the gravel compaction pile method has a problem such as decreased permeability of the drainage material due to clogging. Recently, the study to replace sand with bottom ash which has similar engineering properties with sand is in active. As a fundamental research on bottom ash mixture compaction pile utilizing bottom ash, its behavioral characteristics depending on granular materials and replacement ratio has been simulated numerically. In particular, Settlement Reduction Ratio(SRR) according to the distance from the center of pile was calculated. The main findings were as follows. Change values of Mixture Compaction Pile's SRR according to granular materials showed similar patterns and stiffness of the composite soil is increased depending on the replacement ratio so SRR showed decreased patterns. Especially, when the replacement ratio is in 20~40%, it increase significantly. When the replacement ratio is over 40%, it increase slowly. When considering the economics, 30~40% replacement ratio is appropriate.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1287-1293
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• 2008

In this study, a blend of 2-amino-2-methyl-1-propanol (AMP) and ammonia (NH$_3$) was used to achieve high absorption rates for carbon dioxide (CO$_2$) as suggested at several literatures. The absorption rates of aqueous AMP and blended AMP+NH$_3$ solutions with CO$_2$ and nitrogen dioxide (NO$_2$) were measured using a stirred-cell reactor at 303 K. The effect of the added NH$_3$ to enhance absorption characteristics of AMP was studied. The performances were evaluated under various operating conditions. The absorption rates increased following the increase of the concentration of NH$_3$. The absorption rate of NH$_3$ blended into 30 wt.% AMP solution with NO$_2$ at 303 K was 12.6$\sim$32.6% higher than that of aqueous AMP solution without NH3. Also, the addition of 3 wt.% NH$_3$ to 30 wt.% AMP increased 48.2$\sim$41.6% values for the reactions with CO$_2$ and NO$_2$ at 303 K. Therefore, it clearly shows that the reaction rate of AMP with CO$_2$ and NO$_2$ can be increased by the addition of NH$_3$.