Seungjae Yun

Development and Validation of Wheel Loader Simulation Model

건설기계를 이용한 대규모 토목공사에서 휠로더Key Words: Driving Powertrain(주행부 동력전달), Hydraulic Powertrain(유압부 동력전달), Hydraulic Cylinder Model(유압 실린더 모델), Main Relief Valve(메인 릴리프 밸브), Main Control Valve(메인 릴리프 밸브), Check Valve(체크밸브), Parallel Axis Theorem(평행축 정리) 초록: 본 논문은 Matlab/simulink 기반 휠로더 시뮬레이션 모델의 개발과 검증에 대한 논문이다. 휠로더 시뮬레이션 모델의 개발 및 검증은 실제 휠로더의 생산단계에 앞서 휠로더의 성능을 평가하고 개선하기 위한 목적을 두고 있다. 휠로더 시뮬레이션 모델은 전체적으로 주행부/유압부 동력전달계 모델, 주행부/작업장부 동역학 모델을 포함한4가지 모델로 나뉘어져 있다. 휠로더의 주행 및 작업성능을 평가하고 개선하기 위해서는 언급된 4 가지 모델의 통합 시뮬레이션이 필요하며 통합된 시뮬레이션 모델은 성능평가 외의 연료효율의 최적화, 하이브리드 시스템 및 지능형 휠로더 모델의 개발로써 작업효율 향상에 기여할 수 있을 것이다. 본 논문에 제안된 시뮬레이션 모델은 주행부와 작업부 실험 데이터와의 비교를 통해 검증 되었다. Abstract: This paper presents the development and validation of a wheel loader simulation model. The objective of doing so is to evaluate the performance of the wheel loader and improve its overall performance using Matlab/Simulink. The wheel loader simulation model consists of 4 parts: mechanical/hydraulic powertrain model and vehicle/working dynamic model. An integrated simulation model is required to evaluate and improve the performance of the wheel loader. It is expected that this model will be applied to fuel economizing, improving the pace of operation by using the hybrid system, and the intelligent wheel loader. The performance of the proposed simulation model has been validated by using Matlab/Simulink to compare the driving and the working experimental data.

Effect of Base Layers beneath Ni Catalyst on the Growth of Carbon Nanofibers Using Plasma Enhanced Chemical Vapor Deposition

The relationship between base layers beneath a Ni catalyst and carbon nanofiber (CNF) growth was investigated at a deposition temperature of about 480 °C using a direct-current plasma-enhanced chemical vapor deposition system. Amorphous carbon was deposited on some base layers such as Pt, Ni, Cr, and W, while CNFs were grown on other base layers such as Ag, Mo, Cu, Al, and Ti. In order to explain why CNF growth on some base layers such as Pt, Ni, Cr, and W is absent, a new model unlike existing ones, related to the charge transfer rates of materials, was proposed on the basis of results of scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, and phase diagram analysis.

Driving control architecture for six-in-wheel-driving and skid-steered series hybrid vehicles

This paper presents a driving control method including torque distribution, slip control and regenerative-hydraulic brake control to maximize maneuverability for six-in-wheel-drive and skid-steered series hybrid vehicles. Wheel torque command to each wheel, to track both net longitudinal force and net yaw moment, is distributed based on control allocation method. Because regenerative brake torque does not satisfy desired deceleration under certain speed condition, hydraulic brake system is controlled to obtain suitable brake force rapidly. The maneuvering performance of the six-wheeled and skid-steered vehicle with the proposed driving controller has been compared to that of an Ackerman-steered vehicle with even-distribution controller via TruckSim & Matlab-Simulink co-simulations.