• Journal of Welding and Joining
• /
• v.30 no.5
• /
• pp.22-26
• /
• 2012

Butt-joints of A6061-T6 and AZ31 plates were successfully manufactured by using a friction stir welding method. Off-set free joints and off-set joints were fabricated to investigate the effect of the tool plunge position on the mechanical properties of the joints. Hardness test, tensile test and charpy impact test was performed to evaluate the mechanical properties of the joints. Off-set condition resulted in increase of mechanical properties of the joints. The variation of the hardness distribution in the SZ was also stabilized in the off-set condition. Tensile strength of the off-set joint was about 85% against to that of the AZ31 base metal. Impact absorption energy by Charpy-Impact-Test of the off-set joint also increased by almost 2 times against to that of the AZ31 base metal.

• Laser Solutions
• /
• v.7 no.2
• /
• pp.1-10
• /
• 2004

This work was attempted to join SCP sheet and STS304 sheet by using Nd:YAC laser beam. SCP sheet has good formability and low cost, while STS304 has excellent corrosion resistance and mechanical properties in high temp. In this experiment, butt joint type was used to develop the tailored blank welding for dissimilar steel. Sheets which have different thermal properties. Computer simulation was conducted to obtain the off-set position for efficient welding by considering laser power, scanning speed, focal length and basic properties. The result showed that the optimum thermal distribution was obtained when the laser beam was irradiated at $0.05{\sim}0.1$ mm off-set toward the SCP sheet side. The experiment was conducted based on the result of computer simulation to show the same optimum conditions. Optimum conditions were 3KW in laser beam power, 6m/min in scanning speed, -0.5mm in focal position, 0.1mm off-set toward SCP. Microhardness test, tensile test, bulge test, optical microscopy, EDS, and XRD were performed to observe the microstructure around fusion zone and to evaluate the mechanical properties of optimum conditions, The weld zone had high microhardness values by the formation of the martensitic structure. Tensile test measured the strength of welded region by vertical to strain direction and the elongation of welded region by parallel to strain direction. Bulge test showed $52\%$ formability of the original materials. Bead shape, grain size, and martensitic structure were observed by the optical microscopy in the weld zone. Detailed results of EDS, XRD confirmed that the welded region was connected of martensitic structure.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.34 no.2
• /
• pp.231-237
• /
• 1998

Generally, the three position solenoid valve has veen used for the hydraulic steering gear on account of it’s low cost, simplicity in device, etc. But, there is some off-set because of dead-zone which exists in on-off valves. In this paper, we proposed a combined controller which was added an integral controller to an only on-off one in hydraulic steering gear control system used low speed three position solenoid valve. Experimental results show that the off-set is removed, and the number of valve switching is reduced considerable. The validity of proposed method comparing with an only on-off control was proved by the response experiments.

• Journal of Advanced Marine Engineering and Technology
• /
• v.16 no.1
• /
• pp.27-34
• /
• 1992

In eliminating the nonlinear characteristics such as piston displacement dift and difference in speeds of the reciprocating motion due to their nonsymetrical structure of single rod cylinder, the linear model can be given by equivalent outside disturbance, etc. The position control method of single rod cylinder servosystem using the sliding mode control of VSS was suggested and the good results without off-set are compared with PD control of fixed structure system.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.2
• /
• pp.92-97
• /
• 2011

Vehicle lightings are very important for safe driving during night time. Since the eye recovery time after an exposure to oncoming headlights would take after several seconds, the aiming point of vehicle head lamps have to pass safety requirements. Despite the fact that vehicle inclination is variable with vehicle load conditions, the head lamps aiming point is usually fixed at a constant position which is set by car manufacturer. Consequently, vehicle head lamps under varying load conditions often make people in the opposing vehicle uncomfortable, and even worse, can cause an accident. This paper presents an active vehicle lighting mechanism to automatically adjust its aiming point, or cut-off line, in order to compensate the change in vehicle inclination resulting from load variations. The effectiveness of the proposed method is demonstrated through a set of simulations and experiments with a real vehicle.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.3
• /
• pp.105-115
• /
• 2005

This study was investigated the kinematic factors of the last approach strides and. take off motion for the skill improving of BKH elite male athlete. 'The subjects chosen for the study were BKH and. KASZCZYK Emillian male athletes who were participated in 2003 Dae-Gu Universiad Games. Three high speed video cameras set in 60frames/s setting were used. for recording from the last approach strides to the apex position. After digitizing motion, the Direct Linear Transformation(DLT) technique was employed to obtain 3-D position coordinates, The kinematic factors of the distance, velocity and angle variable were calculated for Kwon3D 3.1. The following conclusions were drawn; 1. It showed longer stride length, as well as faster horizontal and lateral velocity than the success trial during the approach phase. For consistent of the approach rhythm, it appeared that the subject should a short length for obtain the breaking force by the lower COG during the approach phase. 2. The body lean angle showed a small angle by a high COG during the take-off phase. For obtain the vertical displacement of the COG and a enough space form the bar after take-off, it appeared that the subject should increase the body lean angle. 3. For obtain the vertical force during the takeoff phase, it appeared that the subject should keep straight as possible the knee joint. Therefor, the subject can be obtain a enough breaking force at the approach landing.

• Journal of Biosystems Engineering
• /
• v.32 no.5
• /
• pp.284-291
• /
• 2007

This study was to investigate performance of position, basic controls and additional control for man-machine interface on a 3-point hitch of a tractor. The developed additional control was one-touchup, backup, turnup, liftarm limited, PTO on/off and an external control. As a result of experiment, maximum steady state error of response system was lower than $0.8^{\circ}$ and this result showed the function operated normally because the dead band of system set was ${\pm}1^{\circ}$. There was no abnormal situation by switch operation and sensor signal during the performance test. The results of experiment showed the characteristics of the response was sufficient to be used as the position and additional control system for tractors.

• International Journal of Precision Engineering and Manufacturing
• /
• v.9 no.3
• /
• pp.82-84
• /
• 2008

A surface encoder based on the Half-shaded square pattern (HSSP) is presented. The HSSP working as reference grid is composed of the straight lines which are easy to be fabricated and make measuring time short. Since the periodic cell is separated in ON/OFF by the $45^{\circ}$ straight line, the duration from the starting point of scanning to the first rising edge and the duty cycle of the pulse train vary with respect to the position of the starting point. And the relationship between X and Y position and the duration, and duty cycle is described in the simple linear equation. Therefore, it is possible to measure X and Y position with the measured duration and duty cycle without calculating load. Through the test set-up, the feasibility of the proposed surface encoder was verified. Also the future works for improvement of performance were suggested.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.2 no.2
• /
• pp.8-13
• /
• 2005

This paper investigates a fast, accurate and inexpensive hydraulic motor speed control system using high speed on-off solenoid valves. In order to retain the advantages of the two position valve and obtain better performance, the valves are operated by pulse width modulation(PWM) control. PWM signal is generated from a LabWIEW program in microcomputer in order to set up various duty ratio and frequency of carrier wave in PWM signal with varying system parameters. As the results of experiments, the speed control of a hydraulic motor was successfully implemented using on-off solenoid valves. In order to attenuate the pressure ripple and speed variation due to discontinuously controlled flow through the on-off valves, a resonator hose fabricated for automobile power steering system was connected between the valve and a hydraulic motor. From experimental results obtained in the hydraulic motor system with a resonator hose, it was ascertained that the resonator hose showed excellent performances in reducing pressure ripple and motor speed variation.

• Korean Journal of Applied Biomechanics
• /
• v.16 no.1
• /
• pp.139-149
• /
• 2006

This study is to analyze the kinematic variables of inward $1{\frac{1}{2}}$ somersault in platform diver. For the manner, 3 people form the national diving team in the year 2000were chosen as the subjects and two S-VHS video cameras set in 60frames/sec were used for recording their motions. Coordinated raw positions data through digitizing are smoothing by butter-worth's low-pass filterin method at a cut off frequency 6.0Hz. and the direct linear transformation(DLT) method was employed to obtain 3-D position coordinates. The conclusions were as follows. However, horizontal distance which is the change of the COG, form the point of the jump to the point of Event 3 where the player is out of the board range completely, Subject B showed 105.1cm and 71.1cm of the vertical distance which are shorter horizontal distance and higher vertical distance, thus, took a great advantage of the position to prepare for the entry. Therefore, if a player takes higher position by speeding up the vertical velocity at the moment of the jumping off the board, and stays in the air longer, the player can have more time to show his skill. Because of the use of the characteristics of the inward somersault, keeping the safe distance form the board is important but in order to higher the completeness, it is ideal to keep the horizontal distance little over 100cm. Also, the angles of shoulder and elbow from Event 1 to 4, depending on swing of the arms, motions in the air, getting ready for the entry, showed some difference individual by individual, according to the velocity of the thigh and shank showed much difference while getting ready and take-off, and it's because of the individual's different bending and straightening for horizontal and vertical distance.