• Journal of Appropriate Technology
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• v.7 no.1
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• pp.59-71
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• 2021

Hybrid hydrothermal carbonization (Hybrid HTC) technology is a proprietary thermochemical process for two or more organic wastes.The reaction time is less than two hours with temperature range 180~250℃ and pressure range 20~40bar. Thanks to accumulation of the carbon of the waste during Hybrid HTC process, the energy value of the solid fuel increases significantly with comparatively low energy consumption. It has also a great volume reduction with odor removal effect so that it is evaluated as the best solid fuel conversion technology for various organic wastes. In this study of the hybrid hydrothermal carbonization, the effect on the calorific value and yield of Cambodian mango waste were evaluated according to changes in temperature and reaction time. Through the study, parameter optimization has been sought with improving energy efficiency of the whole plant. It is decomposed in the Hydro-Carbonation Technology to Generate Gas. At this time, it is possible to develop manufacturing and production technologies such as hydrogen (H₂) and methane (CH₄). Based on the results of the study, a pilot plant (2t/day) has been proposed for future commercialization purpose along cost analysis, mass balance and energy balance calculations.

• Advances in Energy Research
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• v.7 no.1
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• pp.35-52
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• 2020

The paper proposes a hybrid approach of artificial bee colony (ABC) and grey wolf optimizer (GWO) algorithm for multi-objective and multidimensional engine optimization of a converted plug-in hybrid electric vehicle. The proposed strategy is used to optimize all emissions along with brake specific fuel consumption (FC) for converted parallel operated diesel plug-in hybrid electric vehicle (PHEV). All emissions particulate matter (PM), nitrogen oxide (NOx), carbon monoxide (CO) and hydrocarbon (HC) are considered as optimization parameters with weighted factors. 70 hp engine data of NOx, PM, HC, CO and FC obtained from Oak Ridge National Laboratory is used for the study. The algorithm is initialized with feasible solutions followed by the employee bee phase of artificial bee colony algorithm to provide exploitation. Onlooker and scout bee phase is replaced by GWO algorithm to provide exploration. MATLAB program is used for simulation. Hybrid ABC-GWO algorithm developed is tested extensively for various values of speeds and torque. The optimization performance and its environmental impact are discussed in detail. The optimization results obtained are verified by real data engine maps. It is also compared with modified ABC and GWO algorithm for checking the effectiveness of proposed algorithm. Hybrid ABC-GWO offers combine benefits of ABC and GWO by reducing computational load and complexity with less computation time providing a balance of exploitation and exploration and passes repeatability towards use for real-time optimization.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.1-6
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• 2019

The objective of this study was to investigate performance characteristics of thermal management system(TMS) in a fuel cell electric vehicle with 100kW Fuel Cell(FC) system. In order to build up analytic modelling for TMS, each component was installed and tested under various operating conditions, such as water pump, radiator, 3-Way valve, COD heater, and FC stack etc. and as the results of them, correlations reflecting component's characteristics with flow rate, air velocity were developed. Developed analytic modelling was carried out under various operating conditions on the road. To verify modelling's accuracy, after prediction for optimum coolant flow rate was fulfilled under certain operating conditions, such as FC system, water pump speed, opening of 3-way valve, and pipe resistance, analytic and experimental values were compared and good agreement was shown. In order to predict cold-start operating performance for analytic modelling, coolant temperature variation was analyzed with $-20^{\circ}C$ ambient temperature and duration was predicted to rise in optimum temperature for FC. Because there is appropriate temperature difference between inlet and outlet of FC stack to operate FC system properly, related analysis was performed with respect to power consumption for TMS and heat rejection rate and performance map was depicted along with FC operating conditions.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2002.10a
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• pp.53-67
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• 2002

As in the past, we are concerned today with the magnitudes of mineral resources and the adequacy of these resources to meet future needs. In looking at global resource issues, we should consider the need for the resource, its supply, and the environmental consequences of using it. The need for a resource can become a resource dependency, especially as the global population expands and each of us becomes increasingly dependent upon hundreds of natural materials. Therefore, our great mineral consumption makes the human population a true 'Geologic Force', which will be even more significant in the future when the global population is projected to reach alarming proportions. Although our supplies of mineral resources probably will be sufficient for the 21s1 century, the uneven distribution of minerals in the Earth's crust almost certainly will continue to be a major problem The most likely result will be major shifts in both prices and sources of supply of many mineral resources. As for energy resources, we must avoid an obsessive dependency on one fuel and expand instead to thor energy resources. Finally, because the use of resources affects the environment, we need to focus on resource exploitation and global pollution, particularly in regard to ground water and arable land. We must manage our resources so as to be in balance with our environment. And the accelerated industrialization of South Korean economy over the last three decades has resulted in the mass consumption of nuneral commodities. South Korea has around 50 useful mineral commodities for the mineral industry, among 330 kinds of minerals described. The component ratio of the mining industry sector of the gross national production(GNP) in South Korea dropped from $1.2\%\;in\;1971\;to\;0.34\%$ in 1997 due to the rapid growth of other industries In the countxy. During the period from 1971 to 1997, the average growth rate of mineral consumption in South Korea was $9.13\%$ yearly and that of GNP per capita was $14.97\%$. The mineral consumptions per capita showed a continual Increase during the last 30 years as follows(parenthesis. GNP per capita): 0.99 metric tons in 1971($\$289$), 3.83 metric tons in 1989($\$5,210$), 6.11 metric tons in 1995 ($\$10,037$), and 6.66 metric tons in 1997($9,511). The total amount of mineral consumption in South Korea was 33 million tons of 32 mineral commodities in 1971, and 306 million metric tons of 47 mineral commodities In 1997.

• Proceedings of the KSEEG Conference
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• 2002.10a
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• pp.53-67
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• 2002

As in the past, we are concerned today with the magnitudes of mineral resources and the adequacy of these resources to meet future needs. In looking at global resource issues, we should consider the need for the resource, its supply, and the environmental consequences of using it. The need for a resource can become a resource dependency, specially as the global population expands and each of us becomes Increasingly dependent upon hundreds of natural materials. Therefore, our great mineral consumption makes the human population a true “Geologic Force”, which will be even more significant in the future when the global population is projected to reach alarming proportions. Although our supplies of mineral resources probably will be sufficient for the 21st century, the uneven distribution of minerals in the Earth's crust almost certainly will continue to be a major problem. The most likely result will be major shifts in both prices and sources of supply of many mineral resources. As for energy resources, we must avoid an obsessive dependency on one fuel and expand instead to other energy resources. Finally, because the use of resources affects the environment, we need to focus on resource exploitation and global pollution, particularly in regard to ground water and arable land. We must manage our resources so as to be in balance with our environment. And the accelerated industrialization of South Korean economy over the last three decades has resulted in the mass consumption of mineral commodities. South Korea has around 50 useful mineral commodities for the mineral industry, among 330 kinds of minerals described. The component ratio of the mining industry sector of the gross national production(GNP) in South Korea dropped from 1.2% in 1971 to 0.34% in 1997 due to the rapid growth of other industries in the country. During the period from 1971 to 1997, the average growth rate of mineral consumption in South Korea was 9.13% yearly and that of GMP per capita was 14.97%. The mineral consumptions per capita showed a continual increase during the last 30 years as follows(parenthesis: GW per capita); 0.99 metric tons in 1997($289), 3.83 metric tons in 1989($5, 210), 6.11 metric tons in 1995 ($10, 037), and 6.66 metric tons in 1997($9, 511). The total amount of mineral consumption in South Korea was 33 million tons of 32 mineral commodities in 1971, and 306 million metric tons of 47 mineral commodities in 1997.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.4
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• pp.487-498
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• 2006

Total 438 precipitation samples were collected in Jeju City between 1997 and 2005, and their major ionic components were analyzed. The comparison tests using ion balance, electric conductivity and acid fraction were performed. It was found their correlation coefficients were in the range of 0.977$\sim$0.994, indicating the good quality of collected dam. The volume-weighted mean pH and electric conductivity were 4.8 and 23.0 $\mu$S/cm, respectively. with the ionic strength of 0.23$\pm$0.20 mM. The marine ($Na^+$, $Mg^{2+}$, and $CI^-$), anthropogenic (nss$SO_4{2-}$, $NO_3^-$, and $NH_4^+$) and soil (nss-$Ca^{2+}$) species have contributed to the ionic components of precipitation samples with 43$\sim$74%, 16$\sim$37% and $\sim$5%, respectively. The seasonal variations of $NO_3^-$ and nss-$SO_4^{2-}$ showed a distinct seasonality with higher concentrations in winter than summer, indicating an increase of fossil fuel consumption and a possibility of long-range transport of those pollutants from continental area along the dominant winter westerly. The levels of nss-$Ca^{2+}$ also were appeared the highest in winter and increased comparatively in spring season. possibly due to the soil influences including the Asian Dust. The acidification contribution of nss-$SO_4^{2-}$ and $NO_3^-$ showed 88$\sim$96%, and the free acidity was in the range of 6.0$\sim$40.1%. Interestingly, the backward trajectories for the case of upper 10% nss-$SO_4^{2-}$ and $NO_3^-$ levels have passed through the China continent before their arrival to Jeju. The precipitation of pH below 4.5 has been occurred frequently when the trajectory's path lied over the China continents. On the other hand, the air masses from the North Pacific area were characterized by lower 10% of nss-$SO_4^{2-}$- and $NO_3^-$ concentration, which demonstrated that air mass from the North Pacific was the cleanest among air masses moved to Jeju.