Passenger ride comfort is an integral component of any road vehicle. Ride comport is impacted by vibration resulting from road roughness of low frequency, and also engine vibration of high frequency. The engine mount is an essential component, which acts as a vibration isolator from unwanted vibration. However, vibration isolation requires conflicting design criterion, such as high damping in low frequency range, and low damping in high frequency range. The purpose of this study was to develop a new optimal damping design method for engine mounts based on minimizing H_∞-norm. The damping minimizes H_∞-norm of displacement and force transmissibilities in the wide-frequency vehicle operating range. The proposed optimal damping control was applied to a Magnetorheological (MR) engine mount, to investigate the vibration isolation performance. The feasibility of the proposed method is verified, with some numerical simulation examples.

An optimal design was developed for housing of a 50-ton hydraulic breaker. A four-factor, two-level design was created using the full factorial design, and it was confirmed that the safety factor, the response value, exhibited a curvature. As the curvature was confirmed, a higher-order experiment, a response surface analysis was performed. Based on the Minitab"s optimized prediction of the safety factor and weight, the actual analysis was performed using ANSYS Workbench, the finite element analysis program. As a result, the safety factor was 2.03 and the weight was 3222.2 kg, which was almost consistent with the Minitab’s prediction. The safety factor decreased from 2.33 to 2.03 compared to that in the initial model, but the optimization model can also be judged as being safe because the safety factor was set to 2.00. The weight was reduced by 119.1 kg, from 3341.3 to 3222.2 kg.

In this study, we developed a hydraulic manipulator to assist firefighters and rescue personnel at disaster sites. In the design procedure, we analyzed the manipulator considering the hydraulic actuators as well as the manipulator kinematics and dynamics. For the user interface, a macro/manual operation concept was proposed to provide an effective response in emergency and disaster situations. To cope with abnormalities of the disaster site operator, a protocol for switching local/remote operations was developed. The effectiveness of the hydraulic manipulator and operating system was verified through task implementation experiment.

For years, crane, a chain block, an elevator and a forklift truck have been developed and used to carry heavy loads, but manpower needed where heavy equipment use is not practical. Aging workers suffer from musculoskeletal disorders, and are helped by developing various muscle assisting wearable robots. Industrial wearable robots must meet the payload capacity required for the pilot"s overall operation to ensure safety and operational performance. However, the payload capacity of wearable robot using rotary actuator or linear actuator at the knee joint decreases dramatically in the knee-flexion posture, with reduced moment arms. To solve this problem, the author recommends using Single Acting Hydraulic Telescopic Cylinder Electro Hydrostatic Actuator (SAT-EHA) to increase the torque of the knee in the knee flexion position. The characteristic of telescopic cylinder is high speed in 1st stage and high force in 2nd stage. The Human Universal Mobility Assist-Hybrid (HUMA-H) was developed by designing and fabricating the waist joint to balance the front and rear directions using an electric motor driver. As the payload capacity increases, the robot pilots can squat and stand up with heavy loads. The performance was verified through the operation test and respiratory gas analysis test of the manufactured HUMA-H.

In the gas turbine, the clearance between the blade tip of the rotor and the inside of the stationary casing varies depending on the rotation of the rotor and the heat output of the combustor. Accordingly, the assembly clearance is determined, and the leakage of the gas occurs because of the gap during operation, affecting the efficiency of the system. Thus, designers use a variety of techniques to optimize this clearance, a typical method that reduces the relative variation of the clearance using heating and cooling mechanisms. In this study, we developed a method to control the blade tip clearance through the axial movement of the inclined blade without using heating and cooling mechanisms. Recently, we designed an advanced blade tip clearance control system that can control multi-step, not on-off control, to apply to large gas turbines developed by Doosan. The designed system is hydraulic and can be used with a maximum thrust of 100 tons, and the desired displacement can be moved in multiple stages as required. We have completed the reliability verification of the entire lifecycle level and applied it to the newly developed gas turbine.

This paper presents a robot hand inspired from grasp and grip mechanism of human hand. In human hand, grasp and grip are different terms: Human hand can grasp an object adaptively by individual pulling of each finger’s tendon. Once the fingers make contact with the object, the human hand can grip the object with a larger force by simultaneous pulling of the tendon of each finger. Inspired from this, we propose a mechanism decoupling flexion drive and force-magnification drive for a wire-driven robot hand. The flexion drive consists of electric motors pulling the wire of each finger to make adaptive movement of the robot hand (grasp). The force-magnification drive consist of a hydraulic cylinder that pulls the wire of each finger simultaneously (grip). We also propose adaptive grasp mechanism using spring linkage. It is possible to grasp the irregular objects of limited size without a complex control algorithm or sensor system. We experimentally verified that the grip force of the prototype robot hand exceeds 300N which is 10 times larger than the electric motor alone.

Due to the characteristics of domestic mountainous terrain, the tunnels are increasing. Therefore, an increased budget and more advanced equipment are required to maintain the tunnels cleanliness. As a study on shape optimization using the design of experiment, this paper assessed the design parameters affecting the maximum stress of an articulated hydraulic crane boom. As a result, the maximum stress of an optimized boom was 223.94 MPa at optimal factors. It showed an accuracy of 99.38% compared with the finite element analysis.