With aggravation of environmental contamination and energy resource exhaustion, Hybrid Electric Vehicles (HEV) that can be economically operated with low fuel consumption are receiving greater attention. For performance improvement of such HEV, the development of efficient transmission can be seen as one of core technologies such as performance of components and driving strategy. Dual clutch transmission (DCT) is actively studied as a transmission type for HEV due to its advantages of having excellent power transmission efficiency based on manual transmission characteristic, resolving the problem of power interruption, and realizing driving convenience of automatic transmission (AT). In this paper, one diesel HEV equipped with 6-Speed DCT, modelled using MATLAB/Simulink, and a performance simulator developed for this vehicle are introduced. Driving simulation with driving cycles such as FTP75 and NYCC was performed using the developed performance simulator, and the simulated results regarding state of charge and fuel economy, when AT and DCT are applied to this diesel hybrid vehicle respectively, are compared. This performance simulator can be utilized to develop a control algorithm for improving the fuel economy of HEV with DCT.

A tractor is a farm vehicle that is designed to provide a high tractive effort at low speed. It is used for versatile agricultural tasks such as hauling a trailer, tillage, mowing and construction work. As the intensity of work increases, tractors equipped with automatic transmission become popular due to the work convenience. Though manual and power shuttle transmissions are produced by domestic corporations, development for full-automatic power shift transmissions has never been challenged, and so related technology level is quite low. This paper gives a survey of the automatic transmissions from advanced foreign company, which includes layout of gear train, the way hydraulics controls clutches and brakes, electronic control system. The results are expected to be utilized as a basis in the development of original power train design for tractor.

The numerical analysis of the automatic ship mooring system which was equipped in the ship for trying to berth at the pier was performed in this study. The automatic ship mooring using hydraulic winch was a new method that had not need to change the existing devices and to help a pilot ship of outside. The numerical results of the proposed mooring system including ship motion were that the speed and rolling phenomenon of ship was affected by changing in the ship weight and affected the slope maintenance and yaw degree of ship if there has a trim of stern. Also, a static force of ship at the initial movement was important to calculate the mooring power. The moving force and inertial force of ship on the vertical direction was confirmed for the mooring stability. Therefore, the power and velocity of hydraulic mooring winch should be determined by considering the significant characteristics such as weight, velocity, inertial force and moving force of ship.

Mechanical and electrical properties of a DDV(Direct Drive servo Valve) with electric feedback are analysed via reverse analysis technique in this work. The DDV is disassembled and mechanical parameters, such as spool mass, spring stiffness and port size are identified. The servo amplifier, which is built in the valve, is reversely analysed and the control scheme and gains for several control actions are also identified. The electrical feedback for spool displacement improves much better the valve performance, such as hysteresis and dynamic bandwidth frequency, than an ordinary mechanical feedback valve. Integrating control action with very large gain was adopted in the valve amplifier, and it seemed to give high performance.

Pneumatic system is widely applied in various industry because it have a many advantage(low cost, high safety, etc..). For design of pneumatic system, accurate flow measurement is required. In this study, compressible fluid flow measurement apparatus was designed and built. It uses an isothermal chamber that can approximate isothermal condition. Therefore, it can be measured for flow-rate using pressure response of isothermal chamber. As a result, this apparatus can be measured for sonic conductance and critical pressure ratio of pneumatic components and it required less time and energy than conventional flow meter. The effectiveness of the designed apparatus is proved by experimental result.

The transmission control method of small forklift is classified into pilot control method and direct control method. In pilot control method, the hydraulic circuit which consists a lot of components is very complex so the production process is too costly and time consuming. The direct control method contains fewer components that can be configured to simple hydraulic circuit. It has more advantages because the shift sensitivity of transmission is changed easily via the input profile. In this paper, the controller design and the input profile for system are studied to apply to the direct control method. The input profile consists of Fill section, Hold section and Ramp section. The characteristic of each section is obtained through experiment. As the result, the shift sensitivity and starting performance are effected by Fill section and Hold section.