• Journal of Korean Society for Atmospheric Environment
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• v.30 no.4
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• pp.327-338
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• 2014

The objective of this study is to enhance the effectiveness of Korean Inspection and Maintenance (I/M) program. Three main tasks are: to measure pollutant emissions of in-use light-duty diesel vehicles (LDVs); to evaluate the validity of existing smoke control scheme for low-smoke-emitting vehicles, which have diesel particulate filters, DPF, to meet stringent Euro-5 emission limits; and to assess the necessity and the benefit of $NO_x$ inspection, which is not involved in current I/M program. We measured second-by-second smoke, particulate and gaseous emissions of 27 LDVs using opacity smoke meter, photo-acoustic soot sensor, and portable emissions measurement system, respectively, under the Korean I/M test driving cycle, KD-147. We find that the DPF plays a key role in controlling soot, which can be considered as black carbon contained in particulate matter. Thus, from an I/M perspective, we believe smoke inspection strategies for Euro-5 diesel vehicles should be more focused on the capability of detecting DPF malfunctions or failures, in order to keep DPF properly functional. Fleet averaged distance-specific $NO_x$ emissions are consistently higher than corresponding emission limits, and the values are similar among pre-Euro-3, Euro-3, and Euro-4 vehicle fleets. These findings indicate that the $NO_x$ inspection should be incorporated into current I/M program in order to manage urban $NO_x$ emissions. This research allows the Korean I/M program keep pace with developments in vehicle technologies, as well as the increased emphasis on $NO_x$ with respect to air quality and human health.

• Electrical & Electronic Materials
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• v.12 no.7
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• pp.7-11
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• 1999

Fully sealed field emission display in size of 4.5 inch has been fabricated using single-wall carbon nanotubes-organic vehicle com-posite. The fabricated display were fully scalable at low temperature below 415$^{\circ}C$ and CNTs were vertically aligned using paste squeeze and surface rubbing techniques. The turn-on fields of 1V/${\mu}{\textrm}{m}$ and field emis-sion current of 1.5mA at 3V/${\mu}{\textrm}{m}$ (J=90${\mu}{\textrm}{m}$/$\textrm{cm}^2$)were observed. Brightness of 1800cd/$m^2$ at 3.7V/${\mu}{\textrm}{m}$ was observed on the entire area of 4.5-inch panel from the green phosphor-ITO glass. The fluctuation of the current was found to be about 7% over a 4.5-inch cath-ode area. This reliable result enables us to produce large area full-color flat panel dis-play in the near future. Carbon nanotubes (CNTs) have attracted much attention because of their unique elec-trical properties and their potential applica-tions [1, 2]. Large aspect ratio of CNTs together with high chemical stability. ther-mal conductivity, and high mechanical strength are advantageous for applications to the field emitter [3]. Several results have been reported on the field emissions from multi-walled nanotubes (MWNTs) and single-walled nanotubes (SWNTs) grown from arc discharge [4, 5]. De Heer et al. have reported the field emission from nan-otubes aligned by the suspension-filtering method. This approach is too difficult to be fully adopted in integration process. Recently, there have been efforts to make applications to field emission devices using nanotubes. Saito et al. demonstrated a car-bon nanotube-based lamp, which was oper-ated at high voltage (10KV) [8]. Aproto-type diode structure was tested by the size of 100mm $\times$ 10mm in vacuum chamber [9]. the difficulties arise from the arrangement of vertically aligned nanotubes after the growth. Recently vertically aligned carbon nanotubes have been synthesized using plasma-enhanced chemical vapor deposition(CVD) [6, 7]. Yet, control of a large area synthesis is still not easily accessible with such approaches. Here we report integra-tion processes of fully sealed 4.5-inch CNT-field emission displays (FEDs). Low turn-on voltage with high brightness, and stabili-ty clearly demonstrate the potential applica-bility of carbon nanotubes to full color dis-plays in near future. For flat panel display in a large area, car-bon nanotubes-based field emitters were fabricated by using nanotubes-organic vehi-cles. The purified SWNTs, which were syn-thesized by dc arc discharge, were dispersed in iso propyl alcohol, and then mixed with on organic binder. The paste of well-dis-persed carbon nanotubes was squeezed onto the metal-patterned sodalime glass throuhg the metal mesh of 20${\mu}{\textrm}{m}$ in size and subse-quently heat-treated in order to remove the organic binder. The insulating spacers in thickness of 200${\mu}{\textrm}{m}$ are inserted between the lower and upper glasses. The Y\ulcornerO\ulcornerS:Eu, ZnS:Cu, Al, and ZnS:Ag, Cl, phosphors are electrically deposited on the upper glass for red, green, and blue colors, respectively. The typical sizes of each phosphor are 2~3 micron. The assembled structure was sealed in an atmosphere of highly purified Ar gas by means of a glass frit. The display plate was evacuated down to the pressure level of 1$\times$10\ulcorner Torr. Three non-evaporable getters of Ti-Zr-V-Fe were activated during the final heat-exhausting procedure. Finally, the active area of 4.5-inch panel with fully sealed carbon nanotubes was pro-duced. Emission currents were character-ized by the DC-mode and pulse-modulating mode at the voltage up to 800 volts. The brightness of field emission was measured by the Luminance calorimeter (BM-7, Topcon).

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.9-15
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• 2016

Liquefied petroleum gas (LPG) and compressed natural gas (CNG) are often used as fuel for vehicles because they are clean alternative gas fuels. CNG, as a low-carbon fuel, can contribute to the reduction of greenhouse gas emissions. LPG is often used as fuel for taxis because the performance is almost the same as that of gasoline but the price is lower. In the present study, the exhaust gas and the particle number (PN) of particulate matter, which is a recent environmental issue, were compared between LPG and CNG for the same vehicle. A chassis dynamometer was used to conduct the test according to the Federal Test Procedure (FTP)-75 and Worldwide harmonized Light-duty vehicle Test Procedure (WLTC) modes. The PN values of discharged particles having sizes of 5 nm or larger and 23 nm or larger were measured using two condensation particle counters (CPC). The ratio of carbon dioxide was high in the exhaust gas from the LPG vehicle; the ratio of methane was high in the exhaust gas from the CNG vehicle. The PN values of the emitted particles from the two fuels were similar. The PN values of particles having sizes of 23 nm or smaller were high in the high-speed WLTC mode.

• International Journal of Automotive Technology
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• v.4 no.2
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• pp.65-75
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• 2003

A HEV evaluation program, funded by ADEME, was carried out by a group of Laboratories of different specialties in order to evaluate and compare consumption, emission and component technologies of the three first HEVs put on the market (Toyota Prius, Nissan Tino and Honda Insight). This paper presents the results obtained until now. These results show good consumption and emission performance of the tested vehicles compared to conventional ones. The energy management seems to be globally the same for the three vehicles excepting for cold stans where the Insight allows a very earlier stop of the engine compared to the Tino and especially to the Prius. A mapping of the engine consumption of the Prius and the Insight was performed in order to furnish data for the simulation models. The Permanent Magnet motors of the Prius and Tino have different number of pair poles and then different emf at a given speed. The low emf values of the Prius allow operation at high speed with less field weakening control than for the Tino. The inverters of the Prius and the Tino, controlled by a PWM at respectively 5 kHz and 7 kHz switching frequency, are made of IGBTs with high commutation performances.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.183-194
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• 2013

Liquid urea based SCR has been used in the market to reduce NOx in the exhaust emission of the diesel engine vehicle. This system has several problems at low temperature, which are freezing below $-12^{\circ}C$, solid deposit formation in the exhaust, and difficulties in dosing system at exhaust temperature below $200^{\circ}C$. Also, it is required complicated exhaust packaging equipment and mixer due to supply uniform ammonia concentration. In order to solve these issues, solid urea, ammonium carbonate, and ammonium carbamate are selected as ammonia sources for the application of solid SCR. In this paper, basic research on reaction rate of three ammonia-transporting materials was performed. TGA (Thermogravimetric Analysis) and DTA (Differential Thermal Analysis) tests for these materials are carried out for various heating conditions. From the results, chemical kinetic parameters such as activation energy and frequency factor are obtained from the Arrhenius plot. Additionally, from test results of DSC (Differential Scanning Calorimeter) for these materials, chemical kinetic parameters using the Kissinger method are calculated. Activation energies of solid SCR from this experiment are compared with proper data of literature study, then obtained data of this experiment are used for the design of reactor and dosing system for candidate vehicle.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.92-99
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• 2013

High oil price and global warming problem are being continued all over the world. For this reason, fuel economy and emission of greenhouse gas are regulated by law in many countries. Therefore many companies are researching and producing hybrid electric vehicles (HEVs) which substitute conventional internal combustion engine vehicle. However, these researches and productions are restricted to mainly passenger cars. Because of cost and physical problems, commercial vehicles are difficult to evaluate fuel economy. So simulations are important and it is necessary to know how sensitive parameters that enter into simulation affect. In this paper, forward simulations using AVL Cruise were conducted for analysis of fuel economy for parallel hybrid bus and were repeated by changing each parameter. Based on these results, root mean square errors (RMSE) are calculated for analysis of fuel economy sensitivity. The number of target parameters are 15. These parameters were classified with high and low sensitivity parameter relatively.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.407-408
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• 2002

This paper presents a split cooling system for a new inline 4-cylinder automotive engine. The split cooling system circulates coolant to the cylinder head and cylinder block separately. The coolant flow in the cylinder block is controlled by a $2^{nd}$ Thermostat installed at the outlet of cylinder block. The $2^{nd}$ thermostat closes when the coolant temperature is low. And this makes the coolant flow in cylinder block nearly stagnant, thereby reducing the coolant-side heat transfer coefficient and raising cylinder bore temperature. The $2^{nd}$ thermostat starts to open when the coolant temperature reaches a specified temperature. The test results on engine dynamometer show improved fuel economy and lower exhaust emission which result from the decrease in friction works and cooling loss. Also, several vehicle tests, with application of the new engine have been performed. Fuel economy improvement of 0.5{\sim}2.0%$ yields from different test modes and details are discussed in this paper.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.2
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• pp.160-167
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• 1993

As the major methanol fueled vehicle exhaust components, formaldehyde & methanol conversion over the existing commercial 3-way catalyst was examined in a labolatory tains different Ag loadings on commercial 3-way catalyst, and german commercial catalysts for methanol engine exhaust manufactured by a commercial manufacturer. Silver catalysts were prepared by the wet impregnation of silver nitrate solution on commercial 3-way catalyst. These catalysts were characterized with BET Surface area and pore size distribution. In general, the formaldehyde(HCHO) conversion of the tested catalysts was similar to that of methanol$(CH_3OH)$. At 100$^\circ$C, which is equivalent to the cold start condition, 5wt% Ag cat. showed the most excellent HCHO and $CH_3OH$ conversion. The order of activity for conversion of HCHO & $CH_3OH$ to carbon dioxide and water vapor was as follows ; 5wt% Ag/3-way cat.>2wt% Ag/3-way cat.>german cat. front(1) > german cat. rear(2) > 10wt% Ag/3-way cat.> commercial 3-wat catalyst. However there was no significant activity difference between those tested catalysts in the hot run condition of 400$^\circ$C. Therefore, it could be concluded that the Ag-modified 3-way catalyst was the most effective and practical catalyst system which could be capable of removal the HCHO and methanol at the special condition of low temperature such as cold start condition.

• Journal of Power System Engineering
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• v.20 no.4
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• pp.69-74
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• 2016

Recently, in order to meet the stricter emission regulations, the proportion of after-treatments for vehicle and vessel is increasing gradually. The purpose of this study is to investigate the de-$CH_4$ characteristics of NGOC in front of proposed combined system according to additive catalyst and support ratio. In the case of Pd addition, the de-$CH_4$ performance of 2Pt-2Pd-3MgO/$Al_2O_3$ NGOC was improved by approximately 10 to 20% for the HC components. The de-$CH_4$ performance of 2Pt-2Pd-3Cr-3MgO/$Al_2O_3$ NGOC was higher compared to five kinds of NGOC catalysts, because Cr particle was smaller and dispersion of Pd was increased. The NGOC(Zeolite:$Al_2O_3$(80%:20%)｝catalyst according to support ratio, was improved performance at low temperature region on CO and NO conversion rate.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.868-869
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• 2011

Domestic Foreign automaker's are focused on the high-efficiency, low emission cars development. On the way, the hybrid car is the first priority. Hybrid electric vehicle battery pack configurations, EV Relay one of the key components of the engine driving, to assist in the drive motor to supply electrical energy to the battery is a device for opening and closing of the output device. EV Relay determine the longevity and the replacement cycle, The EV Relay environmental conditions and duty cycle considering the reliability tests are essential requirements of many automotive companies to respond to RFQ, this test is essential. This paper using Maxwell Software for Prediction of the Ev Relay impulse, the theoretical data to obtain the impulse to develop methods for mechanical testing after to take advantage of it.