• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.9
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• pp.727-734
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• 2015

Recently, because of the increased oil prices globally, there have been studies investigating the improvement of fuel-conversion efficiency in internal combustion engines. The improvements realized in thermal efficiency using lean combustion are essential because they enable us to realize higher thermal efficiency in gasoline engines because lean combustion leads to an increase in the heat-capacity ratio and a reduction of the combustion temperature. Gasoline direct injection (GDI) engines enable lean combustion by injecting fuel directly into the cylinder and controlling the combustion parameters precisely. However, the extension of the flammability limit and the stabilization of lean combustion are required for the commercialization of GDI engines. The reduction characteristics of three-way catalysts (TWC) for lean combustion engines are somewhat limited owing to the high excess air ratio and low exhaust gas temperature. Therefore, in the present study, we assess the reaction of exhaust gases and their production in terms of the development of efficient TWCs for lean-burn GDI engines at 2000 rpm / BMEP 2 bar operating conditions, which are frequently used when evaluating the fuel consumption in passenger vehicles. At the lean-combustion operating point, $NO_2$ was produced during combustion and the ratio of $NO_2$ increased, while that of $N_2O$ decreased as the excess air ratio increased.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.150-150
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• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.639-646
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• 2000

Hot air heater with light oil combustion is the most common heater for greenhouse heating in the winter season in Korea. However, since the heat efficiency of the heater is about 80%, considerable unused heat in the form of exhaust gas heat discharges to atmosphere. In order to capture this exhaust gas heat a heat recovery system for plant bed heating in the greenhouse was built and tested in the hot air heating system of greenhouse. The system consists of a heat exchanger made of copper pipes, ${\phi}\;12.7{\times}0.7t$ located inside the rectangular column of $330{\times}330{\times}900mm$, a water circulation pump, circulation plastic pipe and a water tame The total heat exchanger area is $1.5m^2$, calculated considering the heat exchange amount between flue gas and water circulated in the copper pipes. The system was attached to the exhaust gas path. The heat recovery system was designed as to even recapture the latent heat of flue gas when exposing to low temperature water in the heat exchanger. According to performance test it can recover 45,200 to 51,000kJ/hr depending on the water circulation rates of 330 to $690{\ell}$/hr from the waste heat discharged. The exhaust gas temperature left from the heat exchanger dropped to $100^{circ}C$ from $270^{circ}C$ by the heat exchange between the water and the flue gas, while water gained the difference and temperature increased to $38^{circ}C$ from $21^{circ}C$ at the water flow rate of $690{\ell}$/hr. And, the condensed water amount varies from 16 to $43m{\ell}$ at the same water circulation rates. This condensing heat recovery system can reduce boiler fuel consumption amount in a day by 34% according to the feasibility study of the actual mimitomato greenhouse. No combustion load was observed in the hot air heater.

• Journal of Navigation and Port Research
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• v.40 no.4
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• pp.165-171
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• 2016

SEEMP (Ship Energy Efficiency Management Plan) has entered into force since 2013 for the reduction of GHG emission of operating ships. SEEMP guidelines include the hardware modification or installation of energy-saving device on ship. It also includes software based energy-saving technology such as optimum routing, speed optimization, etc. Hardware based technologies are not easy to apply to ongoing vessel due to the operational restriction. Therefore, IT based energy-saving technology was applied and its energy efficiency was evaluated using before and after energy-saving system applied voyage data. SEEMP advises a voluntary participation of EEOI (Ship Energy Efficiency Operation Indicator) use as an indicator of ship energy efficiency operation, and those results were also shown to evaluate the improvement efficiency of energy-saving system.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.113-121
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• 1994

Since two oil shocks in 1970s, all of engine makers have persevered in their efforts to reduce specific fuel consumption and to increase engine power rate as much as possible in marine diesel engines. As a result, the maximum pressure in cylinders of these engines has been continuously increased. It causes direct axial vibration. The axial stiffness of crank shaft is low compared to old types of engine models by increasing the stroke/bore ratio and its major critical speed might occur within engine operation range. An axial damper, therefore, needs to be installed in order to reduce the axial vibration amplitude of the crankshaft. Usually the main critical speed of axial vibration for the propulsion shafting system with a 4-8 cylinder engine exists near the maximum continuous revolution(MCR). In this case, when the damping coefficient of the damper is increased within the allowance of the structural strength, its stiffness coefficient is also increased. Therefore, the main critical speed of axial vibration can be moved beyond the MCR. It has the same function as a conventional detuner. However, in the case of a 9-12 cylinder engine, the main critical speed of axial vibration for the propulsion shafting system exists below the MCR and thus the critical speed cannot be moved beyond the MCR by using an axial damper. In this case, the damping coefficient of an axial damper should be adjusted by considering the range of engine revolution, the location and vibration amplitude of the critical speed, the fore and aft vibration of the hull super structure. It needs to clarify the dynamic characteristics of the axial vibration damper to control the axial vibration appropriately. Therefore authors suggest the calculation method to analyse the dynamic characteristics of axial vibration damper. To confirm the calculation method proposed in this paper, it is applied to the propulsion shafting system of the actual ships and satisfactory results are obtained.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.161-168
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• 2015

Recently, due to various environmental problems such as global warming, increases of international oil prices, exhaustion of resource, a paradigm of world automobile market is rapidly changing from conventional vehicles using internal combustion engine to eco-friendly vehicles using electric power such as EV, HEV, PHEV and FCEV. Generally, in order to measure fuel consumption and pollutant emissions of cars, chassis dynamometer tests are performed on various driving cycles before actual driving test. There are many driving cycles for performance evaluation of conventional vehicles. However, there is a lack of researches on driving cycle for EV. In this study, the urban driving cycle for performance evaluation of electric vehicles was developed. This study is composed of two parts. In the part 1, the urban driving cycle 'GUDC-EV(Gwacheon-city Urban Driving Cycle for Electric Vehicles)' was developed by using driving data, which were obtained through actual driving experiment, and statistic analysis with chronological table. In this paper part 2, in order to verify the developed driving cycle GUDC-EV, virtual EV platforms were configured and simulations were performed with actual driving data using In addition, simulation results were compared with existing driving cycles such as FTP-72, NEDC and Japan 10-15.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.1
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• pp.8-18
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• 2015

Reduction of the fuel oil consumption and corresponding greenhouse gas exhausted from ships is an important issue for today's ship design and shipping. Several concepts and devices on the superstructure of a container ship were suggested and tested in the wind tunnel to estimate the air drag reduction. As a preliminary performance evaluation, air drag contributions of each part of the superstructure and containers were estimated based on RANS simulation respectively. Air drag reduction efficiency of shape modification and add-on devices on the superstructure and containers was also estimated. Gap-protectors between containers and a visor in front of upper deck were found to be most effective for drag reduction. Wind tunnel tests had been carried out to confirm the drag reduction performance between the baseline(without any modification) configuration and two modified superstructure configurations which were designed and chosen based on the computation results. The test results with the modified configurations show considerable aerodynamic drag reduction, especially the gap-protectors between containers show the largest reduction for the wide range of heading angles. RANS computations for three configurations were performed and compared with the wind tunnel tests. Computation result shows the similar drag reduction trend with experiment for small heading angles. However, the computation result becomes less accurate as heading angle is increasing where the massively separated flow is spread over the leeward side.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1319-1328
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• 2016

Since Ballast Water Management Convention has been effected, BWTS, applied to new-building vessels and existing vessels, have been developed from many countries with various treatment methods. However, BWTS is mainly typed Electrolysis, Ozone and UV type. Approximately 70 products have been type approved by the Flag Administrations. For the new-building vessels, the vessels' design and construction have been considered for arrangements and installations for BWTS. However, existing vessels which already construction had finished have problem with selection of BWTS type for installation and arrangement. The selection of the most economized BWTS system is important though, CAPEX has not been made any significant differences. However, OPEX is more important factor. Consequently, detail analysis of OPEX is the key to the selection of the most economized BWTS system and also it can be the purpose of this study. The feasibility study on the main three type of BWTS (Electrolysis, Ozone and UV type) for 175K Bulk Carrier and 57K Cargo ship has been conducted for this study. Because, these three type of BWTS have been the most frequently installed and used and the two type of object vessels are consist of the 40% of the world merchant ship market. For this study, interest rate, project duration (operation time after installation), maintenance cost and fuel oil price are considered as major factor of feasibility study. In addition, expecting Interest rates to sensitivity analysis conducted for more accurate feasibility study. For 175K Bulk carrier, ozone treatment system is more economical than other types. For 57K cargo ship, UV type is considered more economical than other types. However, it is concluded that electrolysis type is more suitable compare to installation space, total weight and electrical power consumption.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.641-649
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• 2021

Fuel oil consumption (FOC) must be minimized to determine the economic route of a ship; hence, the ship power must be predicted prior to route planning. For this purpose, a numerical method using test results of a model has been widely used. However, predicting ship power using this method is challenging owing to the uncertainty of the model test. An onboard test should be conducted to solve this problem; however, it requires considerable resources and time. Therefore, in this study, a deep feed-forward neural network (DFN) is used to predict ship power using deep learning methods that involve data pattern recognition. To use data in the DFN, the input data and a label (output of prediction) should be configured. In this study, the input data are configured using ocean environmental data (wave height, wave period, wave direction, wind speed, wind direction, and sea surface temperature) and the ship's operational data (draft, speed, and heading). The ship power is selected as the label. In addition, various treatments have been used to improve the prediction accuracy. First, ocean environmental data related to wind and waves are preprocessed using values relative to the ship's velocity. Second, the structure of the DFN is changed based on the characteristics of the input data. Third, the prediction accuracy is analyzed using a combination comprising five hyperparameters (number of hidden layers, number of hidden nodes, learning rate, dropout, and gradient optimizer). Finally, k-means clustering is performed to analyze the effect of the sea state and ship operational status by categorizing it into several models. The performances of various prediction models are compared and analyzed using the DFN in this study.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.1067-1073
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• 2021

Regulations to reduce greenhouse gas emissions from ships are gradually being strengthened. EEXI (Energy Efficiency Existing Index) has been introduced in existing ships, and various studies are aimed at achieving the greenhouse gas emission reduction target are currently underway. In this study, we proposed a method to reduce greenhouse gas emissions through reducing fuel oil consumption by applying a solar power generation system to a pure and truck carrier among existing ships engaged in international voyages. The proposed photovoltaic power generation system consists of a photovoltaic module, an energy storage system, and a power conversion device. To confirm applicability, the system was modeled through a power electronics program, and a simulation was performed. In addition, economic analysis was conducted to check the feasibility of application to real ships, and it was confirmed that significant results were derived in the economical aspect after about 11 years had elapsed.