This paper presents a preliminary study on the development of a Light-Emitting Diode (LED) fishing lamp system that can maintain a stationary irradiation region despite ship rolling motions. The proposed system is composed of three modules which include a main control module, a fishing lamp module, and a sensor module. The main control module collects both the operating condition setting of the fishing lamp via the input panel and the tilt angle information of a fishing boat from the sensor module. It provides the conditions and information to the fishing lamp module for controlling the LED modules that maintain a stationary irradiation region. One fishing lamp module is composed of 22 LED modules, a lamp controller, and a temperature sensor. The sensor module is used for measuring the tilt angle of the fishing boat. Tests were carried out to verify the reliability of the LED module driver and the sensor module. The tests showed that the LED modules were reliably controlled, in accordance with the rolling motion of a fishing boat.

This paper presents a scheme for experimentally analyzing bounce, roll and pitch frequencies of major systems of a large truck using a multi-axial road simulator. The excitation input (amplitude and frequency range) for a frequency response test with the multi-axial road simulator is selected in order that bounce, roll and pitch modes are not coupled each other, the excitation amplitude can be reproduced in a specified excitation frequency range, and tires do not lose contact with posters. Three accelerometers, one gyroscope and four displacement meters are used in the frequency response test using the multi-axial road simulator. The reliability of the presented bounce mode frequency response test scheme is validated by comparing the result from a test using the multi-axial road simulator with the result from a road driving test. The road driving test is performed with velocities of 20㎞/h and 30㎞/h, and in an unladen state. The vertical accelerations at the cab and the front axle are measured in the road driving test. The roll and pitch mode frequency response tests are also performed with the presented frequency response test scheme. Roll and pitch frequencies of major systems of a large truck that are hard to acquire from a road driving test are analyzed as well as bounce frequency.

This paper presents an analytical modeling technique for representing a hysteretic behavior of a multi-leaf spring used for a large truck. It divides a nonlinear hysteretic curve of the multi-leaf spring into four parts; loading part, unloading part and two transition parts. It provides conditions for branching to a part of the curve corresponding to a current multi-leaf spring status. This paper also presents a computational modeling technique of the multi-leaf spring. It models the multi-leaf spring with three links and a shackle. It assumes those components as rigid bodies. The links are connected by rotational joints, and have rotational springs at the joints. The spring constants of the rotational springs are computed with a force from the analytical model of the hysteretic curve of the multi-leaf spring. Static and dynamic tests are performed to verify the reliability of the presented techniques. The tests are performed with various amplitudes and excitation frequencies. The hysteretic curves from the tests are compared with those from the simulations. Since the presented techniques reproduce the hysteretic characteristic of the multi-leaf spring faithfully, they contribute on improving the reliability of the computational model of a large truck.