• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.1
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• pp.47-52
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• 2016

Miller timing is one of the promising ways which can improve the fuel consumption of internal combustion engines. Indeed, Miller timing employing an early intake valve close is widely applied to large diesel and gas engines to enhance performance and reduce NOx emissions. In this study, performance evaluation is carried out by 1-D cycle simulation in order to estimate the effect of Miller CAM timing before BDC for a 32 L turbocharged diesel engine. To optimize Miller CAM timing, a single stage turbocharger is matched with an early intake valve close since boost pressure is a significant parameter that can control compression work in a turbocharged engine. The engine simulation result shows that there is enough potential to improve fuel consumption rate and also reduce NOx emissions at the same time.Abstract here.

• Journal of the Korea Society for Simulation
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• v.22 no.4
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• pp.57-66
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• 2013

The needs for reusable 3D visualization tool has been being raised in various industries. Especially in the defense modeling and simulation (M&S) domain, there are abundant researches about reusable and interoperable visualization system, since it has a critical role to the efficient decision making by offering diverse validation and analyzing processes. To facilitate the effectiveness, states-of-the-arts M&S systems are applying VR (Virtual Reality) or AR (Augmented Reality) technologies. To reduce the work burden authors design a collaborative visualization environment based on a commercial game engine Unity3D. We define the requirements of the warfare simulation by analyzing pros and cons of existing tools and engines such as SIMDIS or Vega, and apply functionalities of the commercial game engine to satisfy the requirements. A prototype has been implemented as the collaborative visualization environment of iCAVE at KAIST, which is a facility for immersive virtual environment. The facility is intraoperative with smart devices.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.45-53
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• 1998

Traction control systems(TCS) improve vehicle acceleration performance and stability, particularly on slippery roads through engine torque and/or brake torque control. This research mainly deals with the engine control algorithm based on adjustment of the engine throttle valve opening. Hardware-in-the-loop simulation(HWILS) is carried out where the actual hardware is used for the engine/automatic transmission and TCS controller, while various vehicle dynamics are simulated on real-time basis. Also, use of the dynamometer is made in order to implement the tractive force that a road applies to the tire. Although some restrictions are imposed mainly due to the capability of the synamometer, simplified HWILS results show that the slip control algorithm can improve the vehicle acceleration performance for low-friction roads.

• International Journal of Air-Conditioning and Refrigeration
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• v.14 no.3
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• pp.85-93
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• 2006

The present study has been conducted to simulate dynamics of a gas engine-driven heat pump (GHP) for the design of control algorithm. The dynamic model of a GHP was based on conservation laws of mass and energy. For the control of refrigerant pressures, actuators such as an engine throttle valve, outdoor fans, coolant three-way valves and liquid injection valves were controlled by P or PI algorithm. The simulation results were found to be realistic enough to be applied for the control algorithm design. The model could be applied to build a virtual real-time GHP system so that it interfaces with a real controller for the purpose of developing control algorithm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1183-1194
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• 1998

This paper describes a theoretical model developed for analyzing the heat transfer of automotive cooling systems. From the model, heat transfer rate of automotive cooling systems can be predicted, providing useful information at the early stages of the design and development. The aim of the study is to develop a simulation program for automotive cooling system analysis and a performance analysis program for analyzing heat exchanger. Heat release rate from combustion gas to coolant through cylinder wall in engine cylinder was analyzed by using a two zone combustion model. This paper studied how cooling condition would affect engine heat release rate and measured temperature distribution of coolant in water jacket.

• Journal of KSNVE
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• v.4 no.3
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• pp.319-325
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• 1994

The flucturation of the engine torque appears to be the major source of the torsional vibration of the automotive driveline. The reduction of this torsional vibration has become a significant problem, due to an increase in the flucturation of the torque of recent light weighted powered engines, along with the requirements of higher performance. The torsional vibration of the automotive driveline can be reduced by soothing the fluctuation by adjusting the torsional characteristics of the clutch-disc. Computer simulation of the engine- input gear train is a useful investigative tool on studying the torsional characteristics of the clutch-disc. In this paper, a dynamic model for the automotive driveline was developed, and the engine torque and drag torque of the model were evaluated withe experimental data. By executing a simulation using the model, it has become possible to obtain the clutch-disc torsional characteristics when the engine is idling and the clucth-disc torsional characteristics for reducing the torsional vibration has been suggested.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.165-173
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• 1999

HILS system consists of hardwares which are engine and dynamometer and softwares which is vehicle model without the engine. It is well-known that because of engines's nonlinearity it is difficult to describe an engine exactly and not to lose it reality coincidently. But HILS system is the high technology that can compensate this weakness by using a real engine instead of model. The various experiments regarding the ACC which are not normally available for real vehicle tests have been performed by the HILS system. From the results , the HILS system is expected to decrease the experimental accident rate and save costs and time. Compared with simulation, HILS experimental results show similarities and expected to increase road capacity.

• International Journal of Automotive Technology
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• v.8 no.3
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• pp.289-298
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• 2007

A nonlinear dynamic simulation model from cranking to idle speed is developed to optimize the cold start process of a diesel engine. Physically-based first order nonlinear differential equations and some algebraic equations describing engine dynamics and starter motor dynamics are used to model the performance of cold starting process which is very complex and involves many components including the cold start aiding method. These equations are solved using numerical schemes to describe the starting process of a diesel engine and to study the effects of cold starting parameters. The validity of this model is examined by a cold start test at $-20^{\circ}C$. Using the developed model the effects of the important starting variables on the cold starting processes were investigated. This model can be served as a tool for designing computer aided control systems that improve cold start performance.

• International Journal of Automotive Technology
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• v.5 no.3
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• pp.165-172
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• 2004

Phenomenological models for direct injection diesel engine emissions including NO, soot, and HC were implemented into a full engine cycle simulation and validated with experimental data obtained from representative heavy-duty DI diesel engines. The cycle simulation developed earlier by Jung and Assanis (2001) features a quasi-dimensional, multi-zone, spray combustion model to account for transient spray evolution, fuel-air mixing, ignition and combustion. In this study, additional models for HC emissions were newly implemented and the models for NO, soot, and HC emissions were validated against experimental data. It is shown that the models can predict the emissions with reasonable accuracy. However, additional effort may be required to enhance the fidelity of models across a wide range of operating conditions and engine types.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.12-23
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• 1994

In order to investigate the effect of turbulent intensity on combustion characteristics, new flame factor model was developed. The principal study is the evaluation of interaction of swirl, tumble and unstrutural component of flow characteristics and correlation between turbulent intensity and flame factor. Computational and experimental study has been, performed such as quasi-dimensional cycle simulation, three dimensional flow analysis, engine performance test and diagnostic simulation. From these studies, it was found that flame factor was a function of engine speed and turbulent intensity.