• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.4
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• pp.351-358
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• 2015

In the recent times, the use of gasoline direct injection (GDI) engines has been regarded as a means of enhancing conformance to emission regulations and improving fuel efficiency. GDI engines have been widely adopted in the recent years for their better engine performance and fuel economy compared to those of conventional MPI gasoline engines. However, they present some disadvantages related to the mass and quantity of particulate matter generated during their use. This study investigated the nanoparticle characteristics of the particulate matter exhausted from a GDI engine vehicle installed with different types of gasoline particulate filters, after subjecting it to ultra-lean burn driving conditions. Three metal foam and metal fiber filters were used for each experimental condition. The number concentrations of particles were analyzed for understanding their behavior, and the reduction characteristics were obtained for each type of filter.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.171-178
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• 2014

From now on, in order to meet more stringer diesel emission standard, diesel vehicle should be equipped with emission after-treatment devices as NOx reduction catalyst and particulate filters. Urea-SCR is being developed as the most efficient method of reducing NOx emissions in the after-treatment devices of diesel engines, and recent studies have begun to mount the urea-SCR device for diesel passenger cars and light duty vehicles. That is because their operational characteristics are quite different from heavy duty vehicles, urea solution injection should be changed with other conditions. Therefore, the number and diameter of the nozzle, injection directions, mounting positions in front of the catalytic converter are important design factors. In this study, major design parameters concerning urea solution injection in front of SCR are optimized by using a CFD analysis and Taguchi method. The computational prediction of internal flow and spray characteristics in front of SCR was carried out by using STAR-CCM+7.06 code that used to evaluate $NH_3$ uniformity index($NH_3$ UI). The design parameters are optimized by using the $L_{16}$ orthogonal array and small-the-better characteristics of the Taguchi method. As a result, the optimal values are confirmed to be valid in 95% confidence and 5% significance level through analysis of variance(ANOVA). The compared maximize $NH_3$ UI and activation time($NH_3$ UI 0.82) are numerically confirmed that the optimal model provides better conversion efficiency of $NH_3$. In addition, we propose a method to minimize wall-wetting around the urea injector in order to prevent injector blocks caused by solid urea loading. Consequently, the thickness reduction of fluid film in front of mixer is numerically confirmed through the mounting mixer and correcting injection direction by using the trial and error method.

• Journal of Korean Society of Transportation
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• v.33 no.1
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• pp.40-49
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• 2015

In this study, the effects of inertial driving on a fuel-cut zone were analyzed by measuring the instantaneous variations of fuel consumption and speed. Thirteen sites with 2-8% downhill slopes were selected for the vehicle experiments. The vehicles were driven on the sites in two different driving modes, and the various vehicle states were measured using OBD under driving. For the analysis of the effects of inertial driving, the characteristics of fuel consumption, speed, and rpm were compared between normal and inertial driving. As a result, the fuel consumption was reduced from 24% to 78% according to the downhill grade. The amount of fuel consumption reduction was about 30cc for driving 500m downhill. Fuel cost savings amounting to 35 billion won can be achieved if inertial driving will be done in the case of Munemi-ro3. It is also believed that the reduced fuel consumption and vehicle speed through inertial driving will have considerable environmental and safety benefits.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.2
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• pp.154-166
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• 2009

In this study, 1-hour integrated $PM_{2.5}$ mass and chemical composition concentrations were monitored at the St. Louis-Midwest Supersite in Illinois. Time-resolved samples were collected one week in each of June 2001 (22 June to 28 June), November 2001 (7 November to 13 November), and March 2002 (19 March to 25 March). A total of 427 samples were collected by CAMM (continuous ambient mass monitor) and 15 compounds were analyzed by AAS, PILS (particle-into-liquid sampler), and TOT (thermal optical transmittance) method. PMF was applied to identify the sources and apportion the $PM_{2.5}$ mass to each source for highly time resolved data. In addition, the nonparametric regression (NPR) was applied to identify the predominant directions of local sources relative to wind direction. Also, this study performed compare the NPR analysis and location of actual local point sources at the St. Louis area. The PMF modeling identified nine sources and the average mass was apportioned to gasoline vehicle, road dust, zinc smelter, copper production, secondary sulfate, diesel emission, secondary nitrate, iron+steel, and lead smelter, respectively. These results suggested that this study results will be help for $PM_{2.5}$ source apportionment studies at similar metropolitan area, establish $PM_{2.5}$ standard, and establish effective emissions reduction strategies in Korea.

• Journal of Environmental Policy
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• v.14 no.2
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• pp.73-99
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• 2015

A subsidy policy on early scrapping of old diesel vehicles has been activated to improve air pollution in Seoul metropolitan area. The benefit-cost analysis on this policy evidently shows cost effective as benefit is greater than cost. The policy currently provides 80% of old diesel vehicle's worth within the maximum amount capped which limited the effects on increasing the level of subsidy. Therefore, to induce more old diesel vehicles scrapped, it is needed to consider that the level of subsidy and the maximum amount are raised at the same time. Meanwhile, taking account of insufficient subsidy amount, granting older vehicles more subsidy would be a good way of extending the policy effect.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.163-170
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• 2016

Regulations for the exhaust gas of diesel vehicles are being strengthened every year. Recently, diesel emission regulations for HC, CO, NOx, and particulate matter (PM) have been subject to very strict standards. In the future, the regulation of PM is expected to become stricter. Accordingly, diesel particulate filters (DPFs) have been applied to most diesel vehicles for PM reduction. With increasing engine mileage, ash and soot from the engine exhaust gas accumulate inside the DPF. This accumulation can damage the DPF or degrade engine performance. Therefore, efficient cleaning of the DPF is critical for the maintenance of the engine. If the DPF is well managed through regular cleaning, it can improve the power and fuel economy of the engine and reduce maintenance costs. Therefore, this study was performed to develop a high-efficiency cleaning method for DPFs and an apparatus that can more effectively clean out the accumulated ash and soot.

• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.7-12
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• 2013

As emission regulation for vehicle has been reinforced, many researches carried out for HCNG(hydrogen-natural gas blends) fuel to the conventional compressed natural gas (CNG) engine. However, abnormal combustion such as backfire, pre-ignition or knocking can be caused due to high combustion speed of hydrogen and it can result in over heating of engine or reduction of thermal efficiency and power output. In the present study, improvement of combustion performance was observed with HCNG fuel since it can extend a flammability limit. Knocking characteristics for CNG and HCNG fuel were investigated. Feasibility of HCNG fuel was evaluated by checking the knock margin according to excess air ratio. The operation of engine with HCNG was stable at minimum advance for best torque(MBT) spark timing and knock phenomena were not detected. However, it is necessary to prepare higher knock tendency since possibility of knock is higher with HCNG fuel.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.161-162
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• 2020

Major advanced ports around the world are preparing for environmental regulations such as increased efficiency of ports and low emission of pollutants in ports by utilizing fourth industrial technologies and ICT technologies such as AI, big data, self-driving cars and connected cars. It is also investing in developing fully unmanned terminals to solve the problem of workforce reduction caused by avoidance of 3D industries. However, the introduction of advanced technology is being delayed in domestic ports, which has led to a drop in port efficiency. In addition, port safety accidents have also occurred frequently, seriously affecting port marketing. Thus, the characteristics and types of each container terminal in Korea were analyzed and the factors for introducing autonomous cooperative driving were classified into five section factors and 15 division factors. Hierarchically classified factors will be surveyed on workers working in shipping lines, port construction, container terminals and related ministries.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.1
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• pp.77-84
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• 2015

In 2011, greenhouse gas emissions of transport sector were 85.04 million $tonCO_2eq$ and road emissions accounted for 95% of total emissions in the transport sector. There are few innovative technologies to reduce greenhouse gas emissions aside from eco-driving education and public relation program. Therefore, this paper focused on analyzing optimal acceleration by certain road grades and suggested fuel-efficient driving method for various uphill sections. Scenarios were established by driving modes. Speed profiles were generated by scenarios and speed variations. Each speed profile applied to Comprehensive Modal Emission Model and then each fuel consumption was estimated. Driving mode and speed variation that minimized fuel consumption were driven according to grade percent and uphill distance. When driving in the eco-friendly mode of the driving and speed variation, reduction rate of fuel consumption was evaluated by comparison between eco-driving and cruise control mode. When a vehicle drove under eco-driving mode at 100kph, 90kph and 80kph on uphill road, fuel consumptions were reduced by 33.9%, 30.8% and 5.3%, respectively.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.439-449
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• 2021

The recent reduction in greenhouse gases, interest in environmental pollution such as low-carbon emission policies is increasing. Accordingly, the penetration rate of eco-friendly vehicles, including hydrogen battery vehicles capable of reducing carbon emission, is increasing, and thus it is required for disaster prevention and safety-related measures. In this study, the degree of risk for the concentration distribution of hydrogen when leaking hydrogen fuel vehicles according to ventilation conditions was analyzed through numerical analysis, limited to places in parking lots. As a result, when only one hydrogen tank was released, the combustible volume ratio of hydrogen in the underground parking lot was up to 8.6%, and as ventilation continued, the volume ratio of combustible hydrogen decreased to less than 1% after 150 seconds, indicating that mechanical ventilation is essential. In the case of simultaneous release or stage release of three hydrogen tanks, the final combustible volume ratio of hydrogen is similar, but the increase in the combustible volume ratio of hydrogen in the early stage of release is low, and further research is expected.