• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.11
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• pp.943-956
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• 2003

A numerical program has been developed for the simulation of automotive engine cooling system. The program determines the mass flow rate of engine coolant circulating the engine cooling system and radiator cooling air when the engine speed is adopted by appropriate empirical correlation. The program used the method of thermal balance at individual element through the model for radiator component in radiator analysis. This study has developed the program that predicts the coolant mass flow rate, inlet and outlet temperatures of each component in the engine cooling system (engine, transmission, radiator and oil cooler) in its state of thermal equilibrium. This study also combined the individual programs and united into the total performance analysis program of the engine cooling system operating at a constant vehicle speed. An air conditioner system is also included in this engine cooling system so that the condenser of the air conditioner faces the radiator. The effect of air conditioner to the cooling performance, e.g., radiator inlet temperature, of the radiator and engine system was examined. This study could make standards of design of radiator capacity using heat rejection with respect to the mass flow rate of cooling air. This study is intended to predict the performance of each component at design step or to simulate the system when specification of the component is modified, and to analyze the performance of the total vehicle engine cooling system.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.2
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• pp.128-134
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• 2008

The variable speed engine generator set is interested for an isolated power system due to reduced fuel consumption and less emission. However, because of sluggish dynamic behavior of the internal combustion engine the power quality would be degraded during the sudden load power surge, where the power required by the load is not available by the engine due to the reduced engine speed. An isolated power system based on variable speed engine with a super-capacitor bank can improve dynamic characteristics under such a sudden load change, and power quality, fuel consumption, and pollutants can be improved remarkably. Also, it is verified by the computer simulation that the inverter of 3phase-4leg is compatible to the isolated power system with unbalanced load. In this paper, the feasibility of the system has been verified based on a 26kw commercial diesel engine system.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.617-628
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• 2023

This study aimed to evaluate the engine load factor (LF) of a 90 kW agricultural combine harvester. The combine harvester used in this study is equipped with an electronic engine, and real-time engine data (torque and speed) was collected through a controller area network. The speed of the combine harvester during harvesting operation was divided into three levels (4, 5, and 6 km/h) for the representative operation speed range of 4 to 6 km/h. The LF was calculated using the engine load data measured in real time during harvesting. A weight was applied to the LF for each condition based on a survey of the usage. Results of the field test showed that the LF was 0.53, 0.64, and 0.87 at working speeds of 4, 5, and 6 km/h, respectively. The highest engine load factor was recorded at 6 km/h. Finally, based on the weight for the usage applied, the integrated engine LF was analyzed to be 0.69, which is approximately 144% higher than the currently applied LF of 0.48. A study on LF analysis for the entire work cycle, including idling and driving of the combine harvester, will be addressed in a future study.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.896-907
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• 1995

Titanium 6242(.alpha. + .betha.) alloy has a good strength/weight ratio and is used for aircraft components such as engine disks and compressor blades. When this material is forged at an elevated temperature, the process parameters should be carefully controlled because the process window of this material is quite narrow. In the present investigation, a rigid-thermoviscoplastic finite element method is used to predict the deformation behavior and temperature/strain distributions in an engine disk during near-net shape hot forging. The purpose of the investigation is to obtain a proper ram speed profile, assuming the hydraulic press used in the forging is capable of varying ram speed during loading. In result, it was found that the ram speed at constant strain-rate of 0.5/sec shows a sound deformation behavior, a relatively uniform deformation and a good temperature distribution. This information is also valuable in predicting resulting microstructures in the disk.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.1-5
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• 2000

The conventional PID controller has been extensively used to speed control of marine diesel engines. However one of drawbacks is that its control performance can be degraded if the parameters are fixed on whole operating points. In this paper a scheme for integrating PID control and the fuzzy technique is presented to control speed of a marine diesel engine on whole operating points. At first the PID controller is designed at each speed mode whose parameters are optimally adjusted using a genetic algorithm, Then fuzzy "if-then" rules combine the controllers as a consequence part. To demonstrate the effectiveness of the proposed fuzzy controller a set of simulation works on a marine diesel engine are carried out.rried out.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.57-65
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• 2016

The power flow of an 8-speed automatic transmission was analyzed using a lever analogy for the manufacturing of planetary gears. From the analysis, we found that the engine power was split between the first and second double-pinion planetary gears (DPPG1 and DPPG2), and was then passed to the DPPG3 for the fourth speed. For the fifth speed, the engine power was split between the DPPG1 and DPPG3. For the speeds 6-8, the engine power was passed only to SPPG2, while the seventh speed contained the power circulation.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.63-70
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• 1993

In 1980's to 1990's the marine propulsion diesel engines have been developed into lower speed and longer stroke for the energy saving(small S.F.O.C.). As these new trends the convetional mechnical-hydraulic governors were not adapted to the new requirements and the digital governors have been adopted in the marine use. The digital governors usually use the control algorithms such as the PID control, optimal control, adaptive control and etc. While the engine has delay time and parameter variations these control algorithms have difficulty in considering the stability and the robustness for the model uncertainty. In this study, the $H_{\infty}$ controller design method are applied to the speed control of the low speed marine diesel engine. By comparison the $H_{\infty}$ control results with the PID control results, the validity of the $H_{\infty}$ controller under the delay time and parameter variations is confirmed.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.51-56
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• 2022

In this study an efficient method for detecting and monitoring engine misfiring, focusing on minute speed changes in the crankshaft is proposed., Its validity is verified using various misfiring cases. Typically, the crankshaft speed fluctuates around the normal value depending on the engine misfiring status. Even a minute speed change in the crankshaft can be estimated by measuring the rotation time of each tooth of the 118-tooth flywheel attached to the crankshaft with a 2-MHz timer. Therefore, a speed pattern for an in-line six-cylinder engine consists of 236 tooth rotation speeds corresponding to the two rotations of the crankshaft, in which all the cylinders complete four-stroke cycle. FFT analysis can reduce the number of components of a speed pattern from 236 to just four major components: - fundamental frequency_(f), 2f, 3f, 6f., - This makes the comparison of the misfiring cases simpler and faster. In the experiment, five engine status cases (one normal firing and, four misfiring cases) were simulated. While the 6f component was the largest for the normal case, the f component increased as misfiring occurred one, two apart, and two consecutive times. The 3D FFT pattern comprising the ratio of f, 2f, and 3f, 6f showed that the distance between the misfiring and normal states was larger

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.6
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• pp.87-94
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• 2003

This paper presents results of the development of the turbo generator system with structure which is HSG(High Speed Generator) installed directly to gas-turbine engine. Turbo generator with a high speed motor-generator directly has many advantages aspects of weight, size, lubrication system and complexity of the system compared of conventional turbo generator system with a gear box. But because of direct high speed operation of the high speed generator, we have to need stable high speed motor driving algorithm for perfect engine ignition when engine start. Also we have to need the design of the Power conditioning unit(PCU) for converting high speed AC output power to conventional AC power or needed DC power.

• 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)