• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.10
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• pp.1427-1434
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• 2003

Turbo- or Super-charging has been used to boost engine power for Gasoline- and Diesel Engine since beginning of 20th century. So far turbo-charger has enjoyed a high reputation in the charging field for its technical advantages such as no demand of operation power from engine and an excellent charging effect in a static operation at mid- and high engine speed. A mechanically driven super-charger, however, is now popular due to the high engine power at quick change of the driving mode - high engine torque even at low engine speed. Since super-charger needs operation power from engine, it is difficult to improve its relatively higher fuel consumption than that of turbo-charger. This negative point is still an obstacle to the wide use of supercharger. Super-charger using screw-type compressor will fulfill the purpose to reduce fuel consumption by minimizing operation power owing to no charge at idling or part load driving condition. This study aims to develop power control concept to achieve the minimization of operation power. A screw type super-charger was modified in design partially and installed with an internal bypass valve and a bypass tube to control charging pressure at part load. The various control concepts show a possibility to reduce operation power of super-charger.

• Journal of Korean Society of Transportation
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• v.5 no.2
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• pp.19-35
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• 1987

Transportation energy saving is a national concern because all national petroleum energy is imported. A number of intersections are operating as semi-protected intersections, which have left-turn signal but not exclusive left-turn lanes, because of limited roadways in urban areas. Since the traffic signal methods for the intersections having left-turn signal/lanes cannot be applied to the semi-protected intersection, it is needed to develop a new technique. The purpose of this study was to develop a traffic signal timing method at semi-protected intersections for energy saving and to computerize the method for the practical use. A probability model which could estimate left-turn utilization factors of through traffic during green signal was developed based on field studies. Employing the factors, macro-models to estimate vehicular average delay and proportions of vehicles stopped at the semiprotected intersections were developed. The calculated values of the delay model agreed well with the simulated values of a simulation model using SLAM Ⅱ, a simulation language. Using the two models and the idling fuel consumption rate and the excess fuel consumption per stop-go speed change of vehicles. a traffic signal timing method at semi-protected intersections for energy saving was developed and computerized. The method can be used for other measures of effectiveness such as minimum delay, minimum stop ratio, etc.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.231-234
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• 2003

This paper presents a novel high frequency transformer linked full-bridge type soft-switching phase-shift PWM control scheme DC-DC power converter, which can be used as power conditioner fur small-scale fuel cell power generation system. Using full-bridge soft-switching DC-DC converter topology makes possible to use low voltage high performance MOSFETs to achieve high efficiency of the power conditioner. A tapped inductor filter is implemented in the proposed soft-switching converter topology to achieve soft-switching PWM constant high frequency operation for a wide load variation range. to minimize circulating and idling currents without using additional resonant circuit and auxiliary power switching devices. The practical effectiveness of the proposed soft-switching DC-DC converter is verified in laboratory level experiment with 1 kW 100kHz breadboard setup using power MOSFETs. Actual efficiency of 94-96$\%$ is obtained for the wide load range

• Journal of Energy Engineering
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• v.18 no.3
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• pp.156-162
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• 2009

Cylinder-pressure based combustion analysis provides a mechanism through which a combustion researcher can understand the combustion process. This paper was to identify the most significant sources of cycle-to-cycle combustion variability in a spark ignition engine at idle. To analyse the cyclic variation in the test engine, the burn parameters are determined on a cycle-to-cycle basis through analysis of the engine pressure data. The burn rate analysis program was used in the analysis of the data. Burn parameters were used to determine the variations in the input parameter-i.e., fuel, air, residual mass, and so on.

• Journal of Biosystems Engineering
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• v.32 no.3
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• pp.137-144
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• 2007

An anti-backlash gear was developed to reduce the rattle noise generated from the gearbox of a direct-engine PTO driveline of agricultural tractors under idling. A pair of gears using the anti-backlash gear as driven part was modeled and verified. Using the verified model, a computer simulation was conducted to investigate the effects of design parameters of the anti-backlash gear on the reduction of rattle noise. The optimum values of the design parameters were also determined by the computer simulation. The optimized anti-backlash gear was then manufactured and installed on the experimental PTO driveline for the performance test. Measurement of rattle noise was made to evaluate its performance before and after the driven gear of the PTO gearbox was replaced by the optimized anti-backlash gear. Results of the study were as follows: The optimum values of the design parameters, spring constant and deformation, may be determined by a relationship: $$k{\ge}\frac{4364.7}{150{\delta}-23.564}$$ The optimized anti-backlash gear reduced the rattle noise maximally by 16.9 dBA. This concluded that it would be most effective to use the optimized anti-backlash gear to eliminate the rattle noise in the PTO driveline.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.21-29
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• 2003

Boosting of engine power by using Turbo- or Super-charger is a solution to comply with $CO_2$-regulation in Europe. Turbo-charger is now playing a major role in the field of charging system thank to its technical advantages such as no demand of operation power from engine. A mechanically driven Super-charger, however, is now popular due to quick speed response to change of the driving mode-high engine torque even at low engine speed. Since Super-charger needs operation power from engine, it is difficult to improve its relatively higher fuel consumption than that of Turbo-charger. This negative point is still an obstacle to the wide use of Super-charger. This study aims to develop power control concept to achieve the minimization of operation power when it is not necessary to charge at idling or part load driving condition. A screw type Super-charger was modified in design partially and adapted an internal bypass valve and a bypass tube to control charging pressure at part load. The various control concepts show a possibility to reduce operation power of Super-charger and result in improvement of fuel consumption.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.1
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• pp.57-67
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• 1989

Acoustic intensity method is applied to a 4-cylinder gasoline engine in order to identify the noise sources and the response characteristics. Acoustic intensity is analyzed by 1/3 octave band filter for each center frequency. Radiational characteristics of acoustic intensity at overall and the maximum intensity level are represented by using the contour and three-dimensional plot. It is verified that this method is effective to the assessment of engine noise. It can be found that the maximum intensity is radiated from the front side of the engine under idling condition and the right side of it under 2, 000 rpm running with no loading condition at overall level, and also that the maximum intensity is radiated from the oil pan and the intake and exhaust manifold at the center frequency of 100 Hz.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.90-98
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• 1998

A Dual Mass Flywheel(D.M.F.) system is an evolution to the reduction of torsional vibration and impact noise occurring in powertrain when a vehicle is either moving or idling. The D.M.F. system has two flywh-eels, which is different from the conventional clutch system. One section belongs to the mass moment of in-ertia of the engine-side. The other section increases the mass moment of inertia of the transmission-side. These two masses are connected via a spring/damping system. This reduces the speed at which the dreaded resonance occurs to below idle speed. Since 1984m D.M.F. system has been developed. However, the processes of development of D.M.F. system don't have any difference from the trial and error method of conventional clutch system. This paper present the method for systematical design of D.M.F. system with dimensionless design varia-bles of D.M.F. system, mass ratio between two flywheels, natural frequency rate of two flywheels, and visc-osity coefficient. And expermental results are used to prove these theoretical results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.8
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• pp.102-106
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• 2012

This paper was carried out to survey fire hazard and improvement at the drain pump in air-conditioners. Based on the results of analysis, the proposal of electrical accidents prevention and a construction improvement are as follows. A power connection of the drain pump has two types, an electrical outlet type and direct connection type at control board of air-conditioner. The electrical outlet types need a bulletin sign or education as malfunction of the drain pump include an additional accidents, current leakage and overflowing with water on the floor from breaker trip by exterior cause and breaker off by mistake of worker. On the other hand, the direct connection types prevent a power interruption as exterior cause, but it has some trouble, cut of ground cable and without protection device. Usually it doesn't work by electrician when air-conditioner and the drain pump power work. Therefore an education or countermeasures are recommended for not electrician. Generally malfunction of the drain pump causes accumulated materials into the tank. Even though the accumulated materials lead to an overheating and burning as failure of detector occur an idling, periodic inspection of the air-conditioner filter and the drain pump tank prevent the trouble.

• Journal of Korean Society of Transportation
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• v.8 no.1
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• pp.25-40
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• 1990

This study was undertaken to develop a traffic signal timing method for interconnected and semi-protected-left-turn intersections(the intersections which have left-turn signal but not exclusive left-turn lanes) on four-lane streets for energy saving and to computerize the method for the practical use. For this study, a probability model which could estimate the utilized time of the shared left-turn lane by through traffic during green period was developed based on field studies. The two left-turn treatments, leading and lagging left-turns, were tested for the intersections, and it can be concluded that the leading left-turn was more efficient for the normal urban streets on which through traffic is major traffic. Adopting the leading left-turn macro-models to estimate vehicular average delay and proportions of vehicles stopped at the intersections were developed. Using the two models as well as the idling fuel consumpution rate and the excess fuel consumption per stop-go speed change, a traffic signal timing method for the intersections for energy saving was developed and computerized. The method can be used for more than four-lane streets and for other measures of effectiveness such as minimum delay, minimum stop rates, etc.