• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3044-3048
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• 2008

It is well known that Premixed Charge Compression Ignition (PCCI) diesel engines according to many technologies such a change in injection timing, multiple injection strategy, cooled EGR, intake charging and SCV have the potential to achieve homogeneous mixture in the cylinder which result in lower NOx and PM as well as performance improvements. This may generate merely the infinite number of experimental conditions. The use of Response Surface Methodology (RSM) technique can considerably pull down the number of experimental set and time demand. This paper presents the effects of both fuel injection and engine operation conditions on the combustion and emissions in the PCCI diesel engine system. The experimental results have revealed that a change in fuel injection timing and multiple injection strategy along with various operating conditions affect the combustion, emissions and BSFC characteristics in the PCCI engine.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.1
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• pp.1-6
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• 2014

In this paper, controller propose to prevent compressor surge and improve the transient response of the fuel flow control system of turbojet engine. Turbojet engine controller is designed by applying Artificial Neural Network PID control algorithm and make an inference by applying Levenberg-Marquartdt Error Back Propagation Algorithm. Artificial Neural Network inference results are used as the fuel flow control inputs to prevent compressor surge and flame-out for turbojet engine for UAV. High Gain Observer is used to estimate to compressor rotation speed of turbojet engine. Using MATLAB to perform computer simulations verified the performance of the proposed controller. Response characteristics pursuant to the gain were analyzed by simulation.

• Journal of Mechanical Science and Technology
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• v.19 no.12
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• pp.2321-2329
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• 2005

One means of fulfilling $CO_2$ emission legislation is to downsize engines by boosting their power using turbochargers or mechanical superchargers. This reduces fuel consumption by decreasing the engine displacement. When a turbocharger, which is preferable to a mechanical supercharger in terms of fuel efficiency, is used, there is insufficient availability of exhaust gas energy at low engine speeds, resulting in an unfavorable engine response. Therefore, mechanically driven superchargers have increased in popularity due to their quick response to changing speeds in the transient phase. However, since a mechanical supercharger obtains its driving power from the engine, it is difficult to decrease its fuel consumption. This remains a large negative factor for superchargers, despite their excellent dynamic performance. This study aims to develop a power control concept to improve the fuel economy of a mechanical screw supercharger, which could then be used for engine downsizing.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.1-6
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• 2016

A fuel supply system of heavy-duty CNG engine is composed as a module structure which is integrated by about 6 injectors. There are only one input and output passage for gas fuel supply in this injector module. The response performance for transient operation of an CNG engine is very poor because only one output fuel supply line is connected to the intake pipe after a throttle valve. In this study, a new guideline and internal flow design for the CNG injector module is suggested for the improvement of response performance by fluid dynamic simulations. As a result, the response performance of gas fuel supply can be improved by decreasing the total volume of internal flow passages and a same distance design from each injector to the exit of module shows good response performance and acquirement of linearity of fuel supply. But the injection order has little influence to injection performances.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.1
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• pp.98-105
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• 2017

In recent years, compression ignition engine has been equipped with some control devices such as common rail injection system and turbocharger. In order to control the large number of input parameter appropriately in consideration of $NO_x$, HC and engine power as the engine output objectives. The model construction which reproduces the characteristic value of $NO_x$, HC and engine power from input parameter is needed. In this research, the stepwise method was applied to construct the compression ignition engine model. By using the preliminary experimental data of single cylinder compression ignition engine, the prediction model of $NO_x$, HC and engine power on single injection compression ignition engine was built and compared with the main experimental data.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.16-25
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• 2009

Testing engine performance using an engine dynamometer requires high technical researchers and many facilities. Nowadays, different variables of CAE program are used for identifying the engine performance instead of engine dynamometer test. This is more convenience, as it does not necessitate an abundance of engine dynamometer experiments and, in addition, produces better results. However, CAE programs also contain various variables which can affect engine performance. Those are coupled with each other, thus making it difficult to determine the effectiveness of different variables on engines. DoE (Design of Experiments) methodology is an efficient way to verify the magnitude of effectiveness on engine performance as well as making responses to be optimized at once without trial & error. This study used data from WAVE simulations, which modeled the DOHC SI engine with in-line 4 cylinders at 1500, 3000 and 4500rpm. DoE methodology is designed properly to determine the effectiveness of five variables on power, BSFC, and volumetric efficiency, as well as to find the optimal response conditions at each rpm through a minimized number of experiments. After finishing DoE process, all the results are examined concerning the reliability of test through a verification experiment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1195-1199
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• 2008

In this paper, peak detector of generator's output voltage and variable gain controller are introduced for a fast dynamic response. The conventional r,m.s, signal detected has inherent time delay, and the dynamic response of generator using conventional PID controller has some problem in sudden load change. In this paper, the peak detector and signal selector with variable gain controller is used to overcome this problem. The main controller can check the voltage state from the peak detector. When a sudden load change, the over-voltage and under-voltage signal from peak detector change the controller's gain and exciter's current reference. The proposed scheme can improve the dynamic response, which is verified from experimental test of 200kW diesel engine-generator.

• Journal of Biosystems Engineering
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• v.16 no.2
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• pp.111-117
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• 1991

An empirical model for diesel engine control was obtained using a system identification method. A pseudo-random binary sequence was used as an input signal. Spectral anaylsis was used to find the frequency response of system. Model parameters of transfer functions were obtained using nonlinear regression.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.24-27
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• 2010

This paper presents the design optimization of a linear actuator for fast response of electromagnetic engine valve. The optimization is performed using generic algorithm which is one of global search techniques and not highly dependent on either initial conditions or constraints in the solution domain to maximize the mechanical frequency of the armature mass and valve spring stiffness for fast response of the engine valve. In the results, the mechanical frequency is improved by 30 %.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.1128-1133
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• 2003

A gas driven heat pump (GHP) core design comprises internal combustion engine, compressors incorporated to a cooling/heating system, rubber mountings and belt transmissions. Main excitation farces are generated by an engine, compressors themselves and belt fluctuation. It leads to high vibration level of the mount that can cause damage of GHP elements. Therefore an appropriate design of the mounting system is crucial in terms of reliability and vibration reduction. In this paper oscillation of the engine mount is explored both experimentally and analytically. Experimental analysis of natural frequencies and operational frequency response of the GHP engine mounting system enables to create simplified model for numerical and analytical investigations. It is worked out criteria f3r vibration abatement of the isolated structure. Influence of bracket stiffness between engine and compressors, suspension locations and damper performance is investigated. Ways to reduce excitation forces and improve dynamic performance of the engine-compressor mounting system are considered from these analyses. Implementation of the proposed approach permits to choose appropriate rubber mountings and their location as well as joining elements design A phase matching technique can be employed to control forces from main exciters. It enables to changing vibration response of the structure by control of natural modes contribution. Proposed changes lead to significant vibration reduction and can be easily utilized in engineering practice.