• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.286-290
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• 2004

This paper deals with tipping over of hydraulic excavator's crane work. If the excavator lifts too heavy weight, the excavator will be tipped up. This is account for 38% of whole excavator accidents. In this paper, tipping-over load which is maximum load of excavator can lift with displacement of excavator links, real load and tipping-over rate are computed with Zero Moment Point theory. ZMP is verified with simulation and experiment.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.607-613
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• 2005

In this study, a simplified approach to modeling the dynamic characteristics of passive constrained layer damping treatments in finite element models is presented. The basic concept is to represent multi-layered composite structures using an equivalent single layer. The equivalent properties are obtained by using the RKU (Ross, Kerwin and Ungar) equations. Comparisons are given between results obtained by the dynamic analysis of the simple models implemented in MSC/NASTRAN and by test measurements. Surface damping treatments are applied to automotive panels as well as simple structures. Using the proposed equivalent modeling technique, higher computational efficiency for the damped composite structures has been obtained.

• International Journal of Automotive Technology
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• v.7 no.7
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• pp.813-819
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• 2006

As the vehicle becomes bigger and faster, the importance of vehicle stability in an extreme driving condition caused by sudden steering, road condition or unexpected case has been emphasized. The ESP system is being utilized to improve the handling performance and the vehicle stability. In this study, we implemented various tests and proposed estimation methods for ESP characteristics in extreme driving situations. The estimation methods for ESP proposed in this paper are expected to facilitate developing the control logic and improving the performance of the ESP system.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.1
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• pp.51-64
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• 1994

Analytical study on the thermodynamical cyclic behabiour and characteristics of HFC-l34a refrigerant for automotive air conditionser system for the replacement of existing CFC-12 has been carried out in this paper through development of system performance simulation program, expecially in the view point of system design considerations. The results indicate that HFC-l34a system will give a greater refrigerating capacity than CFC-12 if appropriate engineering measures such as proper codensers, flow controllers, etc., taken for certain operating conditions. The results, however, also show that the operating power for compression process increases over entire temperature range as a result of decreasing volumetric efficiency due to larger specific volume and increased discharging pressure. The present study results indicate that proper selection of condensing and evaporating temperature plus refrigerant control is very important performance factor to have better COP in the HFC-134a system design.

• International Journal of Automotive Technology
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• v.7 no.5
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• pp.637-644
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• 2006

The detection of engine misfire events is one of major concerns in engine control due to its negative effect on air pollution and engine performance. In this paper, a misfire detection system based on crankshaft angular speed fluctuation is developed. Synthetic variable method is adopted for the preprocessing of crankshaft angular speed. This method successfully estimates the work output of each cylinder by finding the effect of combustion energy on the crankshaft rotational speed or acceleration after virtually removing the effect of the internal inertia forces from the measured crankshaft speed signals. The detection system is developed using neural network with the revised synthetic angular acceleration as input which is derived from the preprocessing. Mathematical simulation is carried out for developing and verifying the misfire detection system. Finally, the reliability of the developed system is validated through an experiment.

• Journal of Energy Engineering
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• v.19 no.1
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• pp.32-38
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• 2010

The objective of the research was to study the effects a Miller cycle. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. Miller Cycle without supercharging can increase brake thermal efficiency 1.08% and reduce brake specific fuel consumption 4.58%. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.248-251
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• 2014

As more vehicles become equipped with advanced electronic control systems, more consideration is needed with regards to automotive safety issues related to the effects of electromagnetic waves. Unwanted electromagnetic waves from the antenna, electricity and other electronic devices cause the performance and safety problem of automotive components. In general, Power Integrity and Signal Integrity analysis have been widely used, but these analyses have stayed PCB level. PCB base analysis is different from radiated emission TEST condition so its results are used just for reference. This paper proposes EMC optimization technology using module level 3-dimensional radiation simulation process closed to fundamental test conditions. If module level EMC analysis, which is proposed in this study, is applied to all automotive electronics systems, unexpected EMC noise will be prevented.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.996-997
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• 2008

본 논문에서는 마일드 하이브리드 자동차에 적용 가능한 복합형 에너지 저장 장치의 운용 효율 및 수명 개선이 가능한 스위치 제어 알고리즘을 제안하였다. 제안한 제어 알고리즘은 복합형 에너지 저장 장치를 구성하는 축전지와 울트라커패시터의 전압, 전류, 전력 및 SOC의 변화에 따라 스위치를 적절히 제어함으로써, 시스템 전체의 운용 효율을 개선하고, 또한 축전지에 대전류 충/방전 상황 발생을 제한시켜 축전지의 수명저하 현상을 둔화시킨다. 본 논문에서는 마일드 하이브리드 자동차의 운행 조건을 모사한 사이클 프로파일과 차량 시뮬레이터 장비를 활용하여, 단순병렬 구성의 에너지 저장장치와 스위치 제어 알고리즘이 적용된 에너지 저장장치의 운용효율을 비교함으로써 제안한 알고리즘의 유용성을 확인하였다.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.235-238
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• 2009

To study the relationship between spark ignition and the gap in the nano-scale region, the electric potential was applied to between a Pt-Ir tip and a gold substrate. The tip was sharpened by electro-chemical etching process in the solution of $CaCl_2;H_2O$ and acetone. The radius of tip was measured to be around 200nm and attached to the scanning probe microscope to control the gap between the tip and the substrate. The electric potential of 10V to 80V was applied to initialize the spark. The gaps and the current profile were measured to analyze the characteristics of spark ignition. A spark sustaining time was measured to be between 50ns and 200ns depending on the applied electric potential and the gap between the electrodes. The continuous electric discharge was successfully sustained up to 1 second of spark or arc time. The developed process can be applicable to the micro-scale fabrication of automotive sensors as a similar concept of GTAW.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.129-140
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• 1998

A numerical method is proposed to optimize automotive cam profiles. An acceleration curve of a cam follower motion is described by Hermite spline curves. Because of the intrinsic characteristics of the Hermite curve, it is possible to design an acceleration curve with arbitrary shape. Design variables in the optimization problem are location of control points which define the acceleration curve. Objective function includes dynamic performances as well as kinematic properties of a valve train. Similar optimization procedure was also performed using Polydyne cam profile synthesis method. Optimized profiles using the Hermite curve are proved to be superior to those using the Polydyne method.