• Fire Science and Engineering
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• v.22 no.1
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• pp.99-104
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• 2008

It is important to understand thermal characteristic as a method to estimate the new materials, because spontaneous ignition characterized by causing combustion in the low temperature without ignition source. If can not find out the thermal characteristics of materials, it is frequent that causes of fires could not be found. The danger level of spontaneous ignition material should be estimated and by closely studying its thermal characteristic. However, RPF(Refuse Paper & Plastic Fuel) is a solid matter and getting increasesa year by year because it is an economy profit as alternative energy for limited fossil fuels. Some time RPF occur a fire in the cases of its production process and conservation. Therefore study for thermal stability and critical ignition temperature of RPF was so imperative that the experiment by means of Bombe Calorimeter, TG-DTA, MS80, SIT-II, and Wire Basket Test was implemented. As a result, RPF had a caloric value 26.4-28.3 MJ/kg, and its initial pyrolysis temperature was $192^{\circ}C$ at heating rate 2 K/min. With the result of analysis by MS 80 which is an instrument measuring microscopic calory, pure RPF not containing water has higher caloric value than RPF containing 20% water. Also, SIT-II which is an instrument of insulated auto-ignition was ignited by $118.5^{\circ}C$. This temperature is lower than that of Wire Basket Test. The critical ignition temperature was calculated by Frank-Kamenetskii equation can cause ignition at $80^{\circ}C$ when conserved in the height of 10 m by the standard of infinity slab.

• International Journal of Automotive Technology
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• v.6 no.1
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• pp.1-8
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• 2005

Recently, the HSDI (High Speed Direct Injection) diesel engine has been spotlighted as a next generation engine because it has a good potential for high thermal efficiency and fuel economy. This study was carried out to investigate the in-cylinder flow characteristics generated in a HSDI diesel engine with a 4-valve type cylinder head. The four kinds of cylinder head were manufactured to elucidate the effect of intake port geometry on the in-cylinder flow characteristics. The steady flow characteristics such as coefficient of flow rate $(C_{f})$, swirl ratio (Rs), and mass flow rate (m,) were measured by the steady flow test rig and the unsteady flow velocity within a cylinder was measured by PIV. In addition, the in-cylinder flow patterns were visualized by the visualization experiment and these results were compared with simulation results calculated by the commercial CFD code. The steady flow test results indicated that the mass flow rate of the cylinder head with a short distance between the two intake ports is $13\%$ more than that of the other head. However, the non-dimensional swirl ratio is decreased by approximately $15\%$. As a result of in-cylinder flow characteristics obtained by PIV and CFD calculation, we found that the swirl center was eccentric from the cylinder center and the position of swirl center was changed with crank angle. As the piston moves to near the TDC, the swirl center corresponded to the cylinder center and the velocity distribution became uniform. In addition, the results of the calculation are in good agreement with the experimental results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.9
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• pp.1276-1283
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• 2002

Recently, HSDI (High Speed Direct Injection) diesel engine has been spotlighted as a next generation engine because it has a good potential for high thermal efficiency and fuel economy. This study was carried out to investigate the in-cylinder flow characteristics generated in a 4-valve small diesel cylinder head with a tangential and helical intake port. The flow characteristics such as coefficient of flow rate(Cf), swirl ratio (Rs), and mass flow rate (ms) were measured in the steady flow test rig using the impulse swirl meter and the analysis of in-cylinder flow field was conducted by experiment using the PIV and calculation using the commercial CFD code. As the results from steady flow test indicate, the mass flow rate of the cylinder head with a short distance between the two intake ports is increased over 13% than that of the other head. However, the non-dimensional swirl ratio is decreased approximately 15%. From in-cylinder flow characteristics obtained by PIV and CFD calculation, we found that the swirl center was eccentric from the cylinder center and the velocity distribution became uniform near the TDC. In addition, the results of the calculation are good agreement with the experimental results.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.198-204
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• 2016

In this study, a wind tunnel test was conducted to measure the aerodynamic characteristics of a streamline-designed high-speed bus with the change of wind direction and speed and the result is compared with the aerodynamic performance of a commercialized high-speed bus model (Model-0) manufactured by Zyle Daewoo Bus Corp. Aerodynamic performance of the existing rear-spoiler was tested to prove its aerodynamic effect on the test model bus. From the study, it was found that 24.6 % of the total drag of the original bus model (Model-0) was reduced on the streamline-designed model bus(model-1) without the rear-spoiler but only 14.3 % of the total drag was reduced with the spoiler on the streamlined model bus. It means that the rear spoiler does not work properly with the streamlined model bus (model-1) and should be noted that an optimum design of a rear-spoiler of a vehicle is important to reduce the induced pressure drag and increase the driving stability of a vehicle against yaw motion. The experimental outcome was also compared to the previous numerical research result to evaluate the reliability of the numerical algorithm of the aerodynamic performance analysis of a vehicle. The error rate (%) of the numerical result to the experimental output is about 5.4 % and it is due to the simplified body configuration of the numerical model bus. The drag increases at the higher yaw angle because the transparent frontal area of the model vehicle increases and the downward force increases with the yaw angle as well. It has a positive effect to the driving stability of the vehicle but the moderated downward force should be kept for the fuel economy of a vehicle.

• Journal of Welding and Joining
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• v.34 no.1
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• pp.59-67
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• 2016

The automotive manufactures increase their use of lightweight materials to improve fuel economy and energy usage has a significant influence on the choice of developing materials. To meet this requirements manufacturers are replacing individual body parts with lightweight metals, for these the process treating and painting surfaces is changing. The pre-coated steels are newly developed to avoid the conventional complex and non-environmental painting process in the body-in-white car manufacturing. The development of new joining techniques is critically needed for pre-coated steel sheets, which are electrically non-conductive materials. In the present study, dissimilar combination of pre-coated steel and galvanized steel sheets were joined by the self-piercing rivet, adhesive bonding and hybrid joining techniques. The tensile shear test and free falling high speed crash test were conducted to evaluate the mechanical properties of the joints. The highest tensile peak load with large deformation was observed for the hybrid joining process which has attained 48% higher than the self-piercing rivet. Moreover, the hybrid and adhesive joints were observed better strain energy compared to self-piercing rivet. The fractography analyses were revealed that the mixed mode of cohesive and interfacial fracture for both the hybrid and adhesive bonding joints.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.441-445
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• 2000

Considering international status of our country as world class ship builder and geographical characteristics encircled by sea in three facets, controlling of air pollutants emission from marine engines becomes more and more important issue in recent days. Implementation of immediate pollutants emission control regulation and standardization of test and certification procedure are required to reduce air pollution from marine engines. But cost increments due to additional equipment of emission control device and development and certification test expenses as well as depreciation of fuel economy should be considered. To satisfy those air pollution reduction and economic requirements, we should make our own interpretation of IMO standard and implementation schedule depending on our country's status. For this purpose we measured NOx emission from small and middle class marine engines to calculate emission factor and total pollutant emission in our country. With the comparison and analysis of other countries emission control regulation we proposed basic data of total emission from marine engine and future emission control standard in our country. According to our estimation, 62% of total NOx emission of marine engines comes from fishing boat and 38% from commercial vessels. The portion of NOx emission from marine engine is 18.6% of whole country NOx emission. Due to the voyage characteristics of middle and large vessel and necessity of international harmonization of marine engine pollutants emission control standard, it is inevitable to adopt IMO standard for middle and large marine engines. But considering technological and cost effect of fishing boat operating in near sea, it is resonable to set a standard within 80% of measured value at the moment and gradually implement the same IMO standard in near future.

• Journal of ILASS-Korea
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• v.23 no.4
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• pp.212-220
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• 2018

As increase the number of vehicles, the issue of greenhouse gas that was emitted by them became important. As a result, greenhouse gas (GHG) regulations are being strengthened and efforts are being actively made to reduce greenhouse gas emissions in the automotive industry. In the other hand, regulations for harmful emission of vehicles have been reinforced by step. Especially, the lastly applied step, so called Euro 6, not only decreased NOx limit down to half of Euro 5 but also introduced real driving emission limit for NOx and PN. It is a challenge for manufacturers to meet the recent GHG regulation as well as the latest emission regulation. To overcome these regulations a De-NOx after-treatment system is being applied to diesel vehicles that are known emitting the lowest GHG among conventional internal combustion engines. At the time of the introduction of Euro 6 emission standard in Korea, in the domestic fuel economy certification test, some diesel vehicles emitted more $CH_4$ than Euro 5 vehicles. As a result, it was confirmed that LNT-equipped vehicles emitted a high level $CH_4$ and the level exceeded the US emission standard. In order to determine the reason, various prior literature was investigated. However, it was difficult to find a detailed study on the methane increase with LNT. In this paper, to determine whether the characteristics of vehicles equipped with LNT the affects the above issue and other greenhouse gases, 6 passenger cars were tested on several emission test modes and ambient temperatures with a environment chamber chassis dynamometer. 2 cars of these were equipped with LNT only, other 2 cars had SCR only, and LNT + SCR were applied to remaining 2 cars. The test result shown that the vehicles equipped with LNT emitted more $CH_4$ than the vehicles with SCR only. Also, $CH_4$ tended to increase as the higher acceleration of the test mode. However, as the test temperature decreases, $CH_4$ tended to decreased. $CO_2$ was not affected by kinds of De-NOx device but characteristic of the test modes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.25-31
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• 2018

Recently, research on the development of lightweight vehicle bodies is increasing continuously as a response to fuel economy regulations. To reduce the weight of a vehicle body, a conventional steel plate has been substituted by light weight material with high specific strength and the jointing of multi-materials is generally applied. On the other hand, the customer's demand for safety and emotional quality in NVH (Noise, Vibration and Harshness) is becoming increasingly important. Therefore, a light weight with proper strength and NVH quality is needed. In the view of light weighting and NVH quality, the application of a vibration proof steel plate can be an effective solution but the formability of a sandwich panel is different with a conventional steel sheet. Therefore, careful analysis of formability is required. This study aims to characterize the formability of a sandwich high-strength steel plate. The high-strength steel plates of different thicknesses with resistance spot welding and sealer bonding were analyzed using forming limits diagram through a cup drawing test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5156-5163
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• 2011

Electric Motorcycle is one of the most promising candidates for future transportation because of its outstanding fuel economy and environmental pollution. Before prototyping a realistic electric motorcycle, a reliable simulation program is required to test the capacities of the power sources and optimize the parameters of an electric motorcycle. This process can reduce the expenses during the designing of an electric motorcycle system. In this paper, we present an electric motorcycle system simulation program implemented on Matlab, which can model drivetrain and powertrain systems in an easy, natural way within Simulink and PSAT. And the analysis of design parameters such as max power, capacity, state of charge, slope angle is carried out by the simulation and experimental method. The predicted results by the development model were a good agreement with experimentally obtained results.

• Journal of the Korean Institute of Gas
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• v.25 no.5
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• pp.19-29
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• 2021

Due to the climate changing, the world's countries are tightening regulations on CO2 and air pollutants emission to solve them. In addition, eco friendly vehicles is increasing to replace automobiles in internal combustion engine. Recently, the government is supporting the expansion of hydrogen refueling infrastructure and localization of core equipment in refueling facilities according to the hydrogen economy road map. In this study, design of the Excess flow limiting device in FCEV cylinder valve using by finite element analysis and performed performance tests on prototype. Major test results as hydrostatic strength, continued operation, operation, pressure impulse, leakage showed that the excess flow limiting device meets the performance requirements according to ISO 12619-2 and ISO 12619-11.