• Membrane Journal
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• v.29 no.5
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• pp.237-245
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• 2019

Ammonia nitrogen is well known as a substance that causes the eutrophication with a phosphorus in the water, because it is contained in the industrial wastewater, agricultural and the stockbreeding wastewater. In addition, manganese (Mn) and arsenic (As) are included in the mine treated water, etc., and are known as a source of water pollution. Natural zeolites are used to remove ammonia nitrogen in water but it have a low adsorption capacity. In order to improve the low adsorption capacity of the natural zeolite, ion substitution was carried out with $Na^+$, $Ca^{2+}$, $K^+$ and $Mg^{2+}$. The adsorption capacity and removal rate of ammonia nitrogen ($NH_4-N$) were the highest at 0.66 mg/g and 89.8% in $Na^+$ ion exchanged zeolite. Adsorption experiments of Mn and As were performed using ion exchanged zeolites. Ion exchanged zeolite with $Mg^{2+}$ showed high adsorption capacity and removal rates of Mn and As.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.565-580
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• 2023

In this study, we reviewed and summarized comprehensive roles and importance of natural analogue studies for demonstrating the safety and improving the reliability of the safety for the deep geological disposal of high-level radioactive waste. We also investigated domestic and foreign status of natural analogue studies in order to study and substantiate complex and various radionuclide behaviors in subsurface disposal environments. In addition, we investigated and uranium behaviors in groundwater and rock in uranium deposits including domestic uranium deposits in Ogcheon Metamorphic Belt and biogeochemical interactions in geological environments. Although there are many limitations and uncertainties in directly using the information and data for uranium behaviors obtained from uranium deposits in the disposal safety assessment, the information and data can be utilized in the disposal safety assessment and safety case construction both in qualitative and partly quantitative ways.

• Journal of the Korean Society for Marine Environment & Energy
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• v.20 no.1
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• pp.18-25
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• 2017

Damage of both life and property has been increased by natural disaster under the influence of climate change, thus many natural disaster vulnerability researches have been carried out to make adaptation policy and impact assessment of climate change recently. Their method for assessing vulnerability usually have used proxy variables for making vulnerability indices. However, because their results were too qualitative and relative it tends to be hard to make absolute comparison and establish standard of prevention or adaptation ability. Accordingly, this study aimed at quantifying natural disaster vulnerability using emergy through recognizing disaster as the relations between order and disorder by system approach. As a result, ordering energy (4.66E+22 sej/yr) and ordered structure (1.98E+22 sej) of Busan in 2003 and disordering energy (7.80E+18 sej), disordered parts (4.55E+20 sej) and rebuilding energy (3.87E+20 sej) by typhoon Maemi were analysed. And then, this was compared with Hurricane Andrew in Dade County. Through this comparison, if the prevention ability of Busan increases, disordered parts can be reduced against the more powerful disordering energy. Also, prevention for additional damages by disaster is needed to practical rebuilding action. In conclusion, it was able to figure out the impact of disaster quantitatively by natural systems and urban systems showing as common measure. Based on this study and further research to make effective prevention for how much prevention ability should be increased will contribute to producing the scientific data for disaster management policy in future.

• Journal of the Korean Institute of Gas
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• v.19 no.3
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• pp.9-17
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• 2015

Almost all of the natural gas consumed in South Korea is compressed into very high pressure for the transportation through the underground pipelines, then reduced in pressure regulation stations before delivery to the consumer. For pressure reduction, expansion valves have been used due to the simple and effective installation, but recover none of the energy in the gas during compression. Hence, turbo-expanders are proposed instead of the valves to accomplish the same pressure letdown function and recover some of the compression energy in the form of shaft work converting into electric powers. Here we have theoretically calculated the electric powers at the pressure reduction from 68.7 bar to 23 bar (which are the average values taken at the inlet and outlet points of the expansion valve in medium-pressure regulation stations) according to the inlet conditions of temperature and flow rate. The natural gas is considered as two cases of a pure methane and the mixture of hydrocarbons with a very small amount of nitrogen, and the Peng-Robinson equation of state is employed for the calculation of required thermodynamic properties. The electric energy is recovered as much as 1596 MW(methane) and 1567 MW(mixture) based on the total supply of natural gas in 2013.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2008.04a
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• pp.223-237
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• 2008

• Journal of Bio-Environment Control
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• v.1 no.1
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• pp.14-20
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• 1992

For the high quality and low cost agricultural crops in greenhouse cultivation, it is necessary to use natural energy as much as possible. In order to reduce the fossil fuel consumption and maximize the solar energy utilization in greenhouse heating, a latent heat storage material was developed as a relatively highly concentrative solar energy storage medium. And a solar energy-latent heat storage system was designed and constructed. The experimental research on greenhouse heating effect of the system was performed.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.711-712
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• 2005

• The Korean Journal of Petroleum Geology
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• v.7 no.1_2 s.8
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• pp.19-27
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• 1999

Korea, an energy-resources-poor country, imports $100{\%}$ of its, oil and, natural gas supply, which accounts for the greater part of its total primary requirements. One of the important task of the government is diversification of available energy resources such as oil and natural gas. Natural gas hydrate, which is non-conventional types of natural gas, distributes worldwide, especially in marine and permafrost. It would become a target of natural gas resources in the near future. Especially sigrificant amount of hydrates are expected to be located in the East Sea around Korea Peninsular. This paper describes about a multi-year overall project framework of basic research and technological development of natural gas hydrate in Korea focused on the interpretation of the seismic survey, the characteristics and physical properties of the natural gas hydrate, and the utilizable technology of natural gas hydrates from the status of research and development of the world.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.122-130
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• 2016

This study is a numerical study using commercial simulation program GT-Power on 1.5MW diesel engine for power generation. Performance comparison has done for diesel operation with dual fuel operation for different engine load(50%, 75%, 100%) using the target engine model with additional gas injection system. Effect of using Hi-sene, which is actually being used in island area, instead of diesel was also studied. As a result, under 60% natural gas with diesel condition, BSFC was increased by 32% without modifying system. There was almost no change for natural gas/Hi-sene condition compared with natural gas/diesel condition. Decrease of burned fuel fraction was the main reason of these phenomena. After optimizing system, BSFC was improved by 2%.

• Journal of Energy Engineering
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• v.25 no.2
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• pp.29-36
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• 2016

In this study, diesel/natural gas dual-fuel engine was studied numerically using DoE method. The engine is CI engine for power generation and modelled by 1-D simulation GT-power. The combustion and emission characteristics were analyzed as a function of IVO, IVC and the ratio of natural gas to total fuel enegy. As the proportion of natural gas increases, the BSFC(Brake specific fuel consumption) is increased and BSNOx(Brake specific NOx) is decreased. If specific valve timing to improve the BSFC is applied to the engine, the BSFC is decreased by 1% and simultaneously BSNOx is decreased by 36%.