• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.945-952
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• 2019

The International Maritime Organization (IMO) adopted the International Convention on the Control of Ships' Air Pollutants and Discharge as it became interested in environmental issues such as global warming and air pollution. In addition, a special bill on the improvement of air quality, including in port areas, has recently been enacted in Korea to reduce the amount of fine dust generated. As part of such fine dust reduction measures, feasibility studies have been underway on converting diesel engines into battery electric propulsion systems that do not cause fine dust and emissions. Since the battery electric propulsion system can easily utilize renewable energy sources, and does not generate exhaust gas due to combustion of fuel, small coastal ferries with battery electric propulsion systems that use renewable energy have been operating in Europe and the U.S. for several years. However, they have not been introduced in Korea. Therefore, in this study, we selected small coastal ferries in Korea as target ferries, and performed simulations to study the applicability of electric propulsion with batteries linked to solar power systems. Based on the results, we want to confirm the applicability of battery electric propulsion.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.4
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• pp.129-134
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• 2018

Recently, the artificial neural network (ANN) model is a promising technique in the prediction, numerical control, robot control and pattern recognition. We predicted the outside temperature of greenhouse using ANN and utilized the model in greenhouse control. The performance of ANN model was evaluated and compared with multiple regression model(MRM) and support vector machine (SVM) model. The 10-fold cross validation was used as the evaluation method. In order to improve the prediction performance, the data reduction was performed by correlation analysis and new factor were extracted from measured data to improve the reliability of training data. The backpropagation algorithm was used for constructing ANN, multiple regression model was constructed by M5 method. And SVM model was constructed by epsilon-SVM method. As the result showed that the RMSE (Root Mean Squared Error) value of ANN, MRM and SVM were 0.9256, 1.8503 and 7.5521 respectively. In addition, by applying the prediction model to greenhouse heating load calculation, it can increase the income by reducing the energy cost in the greenhouse. The heating load of the experimented greenhouse was 3326.4kcal/h and the fuel consumption was estimated to be 453.8L as the total heating time is $10000^{\circ}C/h$. Therefore, data mining technology of ANN can be applied to various agricultural fields such as precise greenhouse control, cultivation techniques, and harvest prediction, thereby contributing to the development of smart agriculture.

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.26-34
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• 2014

Due to the rapid energy consumption and fossil fuel abundance reduction, the world is progressively in need of alternative and renewable energy sources such as biodiesel. Biodiesel from microalgae offers high hopes to the scientific world for its potential as well as its non-competition with arable lands. Taking consideration to reduce the cost of production as well as to attain twin environmental goals of treatment and use of animal waste material the microalgal cultivation using piggery manure has been tested in this study. Unialgal strains such as Chlorella sp. JK2, Scenedesmus sp. JK10, and an indigenous mixed microalgal culture CSS were cultured for 20 days in diluted piggery manure using Small Scale Raceway Pond (SSRP). Biomass production and lipid productivity of CSS were $1.19{\pm}0.09gL^{-1}$, $12.44{\pm}0.38mgL^{-1}day^{-1}$, respectively and almost twice that of unialgal strains. Also, total nitrogen and total phosphorus removal efficiencies of CSS was 93.6% and 98.5% respectively and 30% higher removal efficiency compared to the use of unialgal strains. These results indicate that the piggery manure can provide microalgae necessary nitrogen and phosphorus for growth thereby effectively treating the manure. In addition, overall cost of microalgal cultivation and subsequently biodiesel production would be significantly reduced.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.465-472
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• 2015

SEEMP (Ship Energy Efficiency Management Plan) guidelines for a ship's GHG reduction include a machinery modification of hull, an installation of energy efficiency enhanced attachment in hardware methods. It is also possible to bring a ship energy efficiency improvement by fuel-efficient operations or in other software methods. Hardware modification or installation on ship can bring financial burdens to a ship company compared to its improvement expectation. On the other hand, Software based energy-saving technology can be applicable on various ship types, and it is also expected high efficiency of ship energy use compared to hardware based technology in perspective of the investment costs and efficiency. In this paper, it is described that the ship handling simulator based evaluation was carried out using representative ship model of bulk, container and VLCC. Simulation environments were separated into 6 conditions according to the sea-state and weather condition, and the operation results were compared with those before and after energy saving system applied The container ship showed the largest FOC save rate after energy saving system applied although the others also showed energy save rate after using the system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.686-686
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• 2013

Automotive turbochargers have become common in gasoline engines as well as diesel engines. They are excellent devices to effectively increase fuel efficiency and power of the engines, but they unfortunately cause several noise problems. The noises are classified into mechanical noises induced from movement of a rotating shaft and aerodynamic noises by air flow in turbochargers. In addition to, there is a mechanical noise caused from movement of an actuator, electronically controlling a wastegate valve. It is called as valve rattle noise. The actuator is connected to a valve through a linkage. The noise occurs only if the valve is open, where the linkage is freely contact to neighbor structures without being constrained by any external forces. This condition allows impacts by the pulsation of exhaust gas, and the vibration from the impacts spreads out through turbine housing, causing the rattle noise. The noise is not in mechanical operating wastegate turbochargers because the linkage of an actuator is strongly connected by actuating force. For the electronic wastegate turbocharger, this paper proposed a test device to show the noise generating mechanism with a small vibration motor having an unbalanced shaft. It also shows how to reduce the noise - reduction of linkage clearances, inserting wave washers into a connection, and applying loose fitting in bushing embracing a valve lever to turbine housing.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.4
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• pp.87-97
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• 2000

A steady state performance simulation and diagnostics program for the turboprop engine (PT6A-62), which is the power plant of the first developed military basic trainer KT-1 in Republic of Korea, was developed. The developed steady state performance analysis program was evaluated with the performance data provided by the engine manufacturer and with analysis results of GASTURB program, which is well known for the performance simulation of gas turbines. Performance parameters were discussed to evaluate validity of the developed program at various cases such as altitude, flight velocity and part load variation. GPA(Gas Pass Analysis) allows engine performance deterioration to be identified at the module level in terms of reduction in component efficiencies and changes in mass flow. In order to find optimal instrument set to detect the physical faults such as fouling, erosion and corrosion, a gas path analysis approach is utilized. This study was performed in two cases for selection of optimal measurement parameters. One case was considered with the effect of instrument number by changing independent parameter number. The other case was performed with selection of independent parameter set. According to the analysis results, the optimal measurement parameters selected were eight dependent variables such as shaft horsepower, fuel flow rate, compressor exit pressure and temperature, compressor turbine inlet pressure and temperature and power turbine inlet pressure and temperature.

• Clean Technology
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• v.24 no.4
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• pp.339-347
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• 2018

In order to cope with environmental problems and climate change caused by fossil fuels, renewable energy supply is increasing year by year. Currently, waste energy accounts for 60% of renewable energy production. However, waste has a lower calorific value than fossil fuels and contains various harmful substances, which causes serious problems when applied to power generation boilers. In particular, the chlorine in the waste fuel increases slagging and fouling of boiler heat exchangers, leading to a reduction in thermal efficiency and the main cause of high temperature corrosion, lowering facility operation rate and increasing operating cost. In this study, the high temperature corrosion experiments of superheater materials (ASME SA213/ASTM A213 T2, T12 and T22 alloy steel) by alkali chlorides were conducted, and their corrosion characteristics were analyzed by the weight loss method and SEM-EDS. Experiments show that the higher the temperature and chloride content, the more corrosion occurs, and KCl further corrodes the materials compared to NaCl under the same condition. In addition, the higher the chromium content of the material, the better the corrosion resistance to the alkali chlorides.

• Environmental and Resource Economics Review
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• v.28 no.2
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• pp.231-276
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• 2019

This paper analyzed the impact of the penetration of EV(electric vehicle) and FCEV(fuel cell electric vehicle) into the automobile industry, using a static CGE approach. There are contrasting view on the economic impact of EV/FCEV penetration: negative economic impact due to shrunken intermediate inputs versus positive impact because of input saving technical progress. Regarding environment, there is no clear consensus whether EV or FCEV will contribute to the reduction of $CO_2$ emissions in Korea. This study attempts to provide an answer to these questions. By giving shocks to the input coefficients of automobile industries and automobile using sectors, as well as to the final demands for energies. we integrated the Bass diffusion model into the CGE framework, The result suggests that the EV penetration has adverse impact on the $CO_2$ emission while the FCEV penetration has positive impact. On the other hand, both EV and FCEV have positive impacts on GDP. When considering automobile manufacturing sectors only, adverse impacts on $CO_2$ are demonstrated both for EV and FCEV. However, since the size of $CO_2$ increase is small, these results does not alter the overall effects.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.127-137
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• 2019

Zr electrorefining is demonstrated herein using Zirlo tubes in a chloride-fluoride mixed molten salt in the presence of $AlF_3$. Cyclic voltammetry reveals a monotonic shift in the onset of metal reduction kinetics towards positive potential and an increase in intensity of the additional peaks associated with Zr-Al alloy formation with increasing $AlF_3$ concentration. Unlike the galvanostatic deposition mode, a radial plate-type Zr growth is evident at the top surface of the salt during Zr electrorefining at a constant potential of -1.2 V. The diameter of the plate-type Zr deposit gradually increases with increasing $AlF_3$ concentration. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) analyses for the plate-type Zr deposit show that trace amount of Al is incorporated as Zr-Al alloys with different chemical compositions between the top and bottom surface of the deposit. Addition of $AlF_3$ is effective in lowering the residual salt content in the deposit and in improving the current efficiency for Zr recovery.

• Journal of Climate Change Research
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• v.2 no.2
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• pp.69-77
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• 2011

While increased use of energy and fossil fuel in the recent years could worsen air quality and climate change, only few studies have been conducted on estimation of greenhouse gas emissions and characterization of emission types by sectors and regions in Korea. In this study, greenhouse gases emissions based on resions(Si, Gun, Gu) and emitted sectors(industry, transport, cemmercial and institutional, residential, waste, agriculture, others) were investigated using GHG-CAPSS(Greenhouse GasClean Air Policy Support System) developed to support to national and regional greenhouse gases reduction strategies. GHG-CAPSS follows IPCC(Intergovernmental Panel on Climate Change) Guideline methodology to categorize the emission sources and estimation of greenhouse gases using bottom-up approach. Estimated total greenhouse gases emissions were 588,011 thousand tons as $CO_2$ equivalent. Industry(50.1%) sector exhibited the highest portion followed by transport(17.6%), commercial and institutional(12.6%), residential(12.6%), waste(2.6%), agriculture(2.5%). Based on regional estimation, Gyeonggi(14.9%) demonstrated the highest emitted greenhouse gases among big cities followed by Jeonnam(12.4%), Gyeongbuk(11.0%), Ulsan(9.2%) and Seoul(8.9%).