• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.86-92
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• 2003

To analyze the characteristics of ozone formation, measurements of the concentrations of individual exhaust hydrocarbon species have been made under various engine operating parameters in a 2-liter 4-cylinder engine for natural gas and LPG. Tests were performed at constant engine speed, 1800 rpm for two compression ratios of 8.6 and 10.6, with various operating parameters, such as excess air ratio of 1.0~1.6, bmep of 250~800 na and spark timing of BTDC 10~$55^{\circ}$. It was found that the natural gas gave the less ozone formation than LPG in various operating conditions. This was accomplished by reducing the emissions of propylene($C_3H_6$), which has relatively high maximum incremental reactivity factor, and propane($C_3H_8$) that originally has large portion of LPG. In addition, the natural gas show lower values in the specific reactivity and brake specific reactivity. Higher compression ratio of the test engine showed higher non methane HC emissions. However, specific reactivity value decreased since fuel species of HC emissions increase. brake specific reactivity showed almost same values under high bmep, over 500kPa for both fuels. This means that the increase of non methane HC emissions and the decrease of specific reactivity with higher bmep affect each other simultaneously. With advanced spark timing, brake specific reactivity values of LPG were increased while those of natural gas showed almost constant values.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1303-1309
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• 2003

This paper presents the static and dynamic measurements for the strength and motion characteristics as well as the improved procedures to assess strength of wheel loaders. Two scenarios for static measurement were decided by which cylinder was actuating. The dynamic measurement was performed for two types of motion, that is, simple reciprocation of the working devices and actual working motion including traveling, digging and dumping. The measured items were stresses, cylinder pressures and strokes. Stress induced by bucket working showed higher level than that by boom working. The measured cylinder speeds were relatively superior to the design speeds. Working stress histories were thought to be closer to static rather than dynamic. A fully assembled FE model was prepared for structural analysis. In this paper, a more simple method was suggested to avoid nonlinearity caused by heave of rear frame under digging forces. Also how brake affected on structural behavior and digging force was examined closely in relation with tire pressure. It was confirmed that the overall stress level of wheel loader during turning traveling with loaded bucket was far lower than the yield stress of material.

• Smart Structures and Systems
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• v.29 no.5
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• pp.653-660
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• 2022

Gravel scattering that is generated during operation of high-speed railway vehicle is cause to damage of vehicle such as windows, axle protector and so on. Especially, those are frequently occurred in winter season when snow ice is generated easily. Above all, damage of vehicle windows has not only caused maintenance cost but also increased psychological anxiety of passengers. Various methods such as heating system using copper wire, heating jacket and heating air are applied to remove snow ice generated on the under-body of vehicle. However, the methods require much run-time and man power which can be low effectiveness of work. Therefore, this paper shows that large-area heating system was developed based on heating coat in order to fundamentally prevent snow ice damage on high-speed railway vehicle in the winter season. This system gives users high convenience because that can remotely control the heating system using IoT-based wireless communication. For evaluating the applicability to railroad sites, a field test on an actual high-speed railroad operation was conducted by applying these techniques to the brake cylinder of a high-speed railroad vehicle. From the results, it evaluated how input voltage and electric power per unit area of the heating specimen influences exothermic performance to draw the permit power condition for icing. In the future, if the system developed in the study is applied at the railroad site, it may be used as a technique for preventing all types of damages occurring due to snow ice in winter.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.24-31
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• 2002

An experimental study was conducted to investigate the effects of EGR (Exhaust Gas Recirculation) variables on performance and emission characteristics in a 2-liter 4-cylinder spark-ignition LPG fuelled engine. The effects of EGR on the reduction of thermal loading at exhaust manifold were also investigated because the reduced gas temperature is desirable for the reliability of an engine in light of both thermal efficiency and material issue of exhaust manifold. The steady-state tests show that the brake thermal efficiency increased and the brake specific fuel consumption decreased with the increase of EGR rate in hot EGR and with the decrease of EGR temperature in case of cooled EGR, while the stable combustion was maintained. The increase of EGR rate or the decrease of EGR temperature results in the reduction of NOx emission even in the increase of HC emission. Furthermore, decreasing EGR temperature by $180^{\circ}C$ enabled the reduction of exhaust gas temperature by $15^{\circ}C$ in cooled EGR test at 1600rpm/370kPa BMEP operation, and consequently the reduction of thermal load at exhaust. The optimization strategy of EGR application is to be discussed by the investigation on the effect of geometrical characteristics of EGR-supplying pipe line.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.899-905
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• 2000

The characteristics of air flow and engine performance with swirl ratio variance of intake port In a turbocharged DI diesel engine was studied in this paper. The intake port flow is important factor which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. The swirl ratio for ports was modified by hand-working and measured by impulse swirl meter. For the effects on performance and emission, the brake torque and brake specific fuel consumption were measured by engine dynamometer and NOx, smoke were measured by gas analyzer and smoke meter. As a result of steady flow test, when the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. And as the swirl ratio is increased, the mean flow coefficient is decreasing, whereas the gulf factor is increasing. Also, through engine test its can be expected to meet performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.5-10
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• 2005

The effect of ultrasonic energy for diesel fuel and blend oil has been revealed in this paper. The experimental setup consisted of a high speed diesel engine with 4 cylinder, dynamometer and ultrasonic fuel feeding system. Ultrasonic energy was added to diesel fuel and blend oil, which is a blend of diesel fuel and rape-seed oil. As engine speed was changed, engine torque and power, brake specific fuel consumption and thermal efficiency were measured in detail. As the results, by adding ultrasonic energy to diesel fuel and blend oil, the engine performance was improved in range of the experiment. The effect of improvement on brake specific fuel consumption and thermal efficiency for blend oil is higher than that for diesel fuel. When ultrasonic energy was added to diesel fuel or blend oil, a rise in engine torque for diesel fuel was higher than that for blend oil, but the effect of ultrasonic energy was small. From these results, it may be desirable to add ultrasonic energy to blend oil for the use of blend oil to diesel engine.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.769-772
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• 2010

The objective of the current research work is to investigate the usage of biodiesel combined with the use of EGR in order to reduce the emission of all regulated pollutants from diesel engines. A single cylinder, air cooled, constant speed direct injection diesel engine was used for the experimental work and a cold EGR system was developed and fitted to the engine. Concentrations of HCs, NOx, and CO from the exhaust gas along with the smoke opacity were measured. Engine performance parameters such as the brake thermal efficiency (BTE) and the brake specific energy consumption (BSEC) were also calculated from the measured data. The results from the present investigation suggest that 25-30% EGR rate could give excellent NOx reduction without any significance penalty on smoke opacity or BSEC under the engine load of up to 40%. Under the full load condition, 15% EGR rate was found to be an option while higher EGR rate resulted in inferior performance and heavy smoke.

• Journal of Mechanical Science and Technology
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• v.15 no.10
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• pp.1442-1450
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• 2001

The EGR system has been widely used to reduce nitrogen oxides (NO$\_$x/) emission, to improve fuel economy and suppress knock by using the characteristics of charge dilution. However, as the EGR rate at a given engine operating condition increases, the combustion instability increases. The combustion instability increases cyclic variations resulting in the deterioration of engine performance and emissions. Therefore, the optimum EGR rate should be carefully determined in order to obtain the better engine performance and emissions. An experimental study has been performed to investigate the effects of EGR on combustion stability, engine performance,70x and the other exhaust emissions from 1.5 liter gasoline engine. Operating conditions are selected from the test result of the high speed and high acceleration region of SFTP mode which generates more NO$\_$x/ and needs higher engine speed compared to FTP-75 (Federal Test Procedure) mode. Engine power, fuel consumption and exhaust emissions are measured with various EGR rate. Combustion stability is analyzed by examining the variation of indicated mean effective pressure (COV$\_$imep/) and the timings of maximum pressure (P$\_$max/) location using pressure sensor. Engine performance is analyzed by investigating engine power and maximum cylinder pressure and brake specific fuel consumption (BSFC)

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3013-3018
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• 2008

Supercharging system was adopted to investigate the influence of boost pressure on operating range, brake specific fuel consumption (BSFC) and exhaust emissions by using a supercharger at low temperature diesel combustion (LTC) condition in a 5-cylinder 2.7 L direct injection diesel engine. The experimental parameters such as injection quantity, injection timing, injection pressure and exhaust gas recirculation (EGR) rate were varied to find maximum operating range. The result showed that operating range with boost was expanded up to 41.9% compared to naturally aspirated LTC condition due to increased mixing intensity. The boosted LTC engine showed low BSFC value and dramatically reduced soot emission under all operating range compared with high speed direct injection (HSDI) mode. Finally, this paper presents the boosted LTC map of emission and the strategy of improved engine operating range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.1
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• pp.10-17
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• 2007

For the purpose of optimal control of anti-lock brake system, precise dynamic characteristics analysis of the hydraulic modulator, especially solenoid valve is necessary. However, most of researches so law have dealt with dynamic characteristic analysis of valve itself and the results have been restrictive to apply on the actual ABS modulator, where hydraulic pressure is acting. In this study, mathematical modeling and experimental analysis were executed in order to evaluate the valve dynamic characteristics when the hydraulic pressure applied. High pressure on the master cylinder effects on the valve dynamic characteristics have been analyzed quantitatively and performance improvement methods have been suggested varying the design factor. Consequently, results of solenoid valve dynamic characteristics analysis derived in the study can be utilized criteria for the optimal control of anti-lock brake system.