• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.66-72
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• 1999

Robot calibration is very important to improve the accuracy of robot manipulators. However, the calibration procedure is very time consuming and laborious work for users. In this paper, we propose a method of relative error compensation to make the calibration procedure easier. The method is completed by a Pi-Sigma network architecture which has sufficient capability to approximate the relative relationship between the accuracy compensations and robot configurations while maintaining an efficient network learning ability. By experiment of 4-DOF SCARA robot, KIRO-3, it is shown that both the error of joint angles and the positioning error of end effector are drop to 15$\%$. These results are similar to those of other calibration methods, but the number of measurement is remarkably decreased by the suggested compensation method.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.4
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• pp.449-454
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• 2012

The method for spraying of liquid through an electrical filed has become a printing method since it can make very small droplet. To increase the reliability using the electro-hydrodynamic (EHD) jet printing, the jetting status needs to be monitored. Vision measurement techniques using high speed camera has been used to visualize the jet images. However, it requires image processing of a lot of images after image acquisitions. So, it is difficult to understand jet behavior such as jetting frequency, jet repeatability etc. In this work, a low cost electrical current measurement method was developed to measure electrical current from EHD jet printing. To verify the jetting monitoring capability of developed circuit, images from high speed camera were processed for comparison purpose.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1085-1089
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• 2007

An acoustic topology optimization method is developed to optimize the acoustic attenuation capability of a muffler. The transmission loss of the muffler is calculated by using the three-point method based on finite element analysis. Each element of the finite element model is assumed to have the variable acoustic properties, which are penalized by a carefully-selected interpolation function to yield clear expansion chamber shapes at the end of topology optimization. The objective of the acoustic topology optimization problem formulated in this work is to maximize the transmission loss at a target frequency. The transmission loss value at a deep frequency of a nominal muffler configuration can be dramatically increased by the proposed optimization method. Optimal muffler configurations are also obtained for other frequencies.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.3
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• pp.220-226
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• 2011

This paper presents the novel work for source localization of serial multiple impacts in a plate sructure. It is difficult to identify the source of serial multiple impacts with the current source localization techenology(SLT) because of the overlapping of dispersive wave induced by multiple impacts and the reflaction from the edge of the plate. In this paper, the new method is suggested for source localization. The method is developed based on the SLT with pre-signal processing such as some limitation for the selection of three sensors, the frequency range for TFA and impact time interval. Results from numerical simulation and experiment in isotropic plate structure are presented, which show the capability of the proposed method.

• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.1941-1948
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• 2004

This paper presents a novel design of indoor airship having a passive wheeled mechanism and its stationary position control. This wheeled blimp can work both on the ground using wheeled vehicle part and in the air using the floating capability of the blimp part. The wheeled blimp stands on the floor keeping its balance using a caster-like passive wheel mechanism. In tele-guidance application, stationary position control is required to make the wheeled blimp naturally communicate with people in standing phase since the stationary blimp system responds sensitively to air flow even in indoor environments. To control the desired stationary position, a computed torque control method is adopted. By performing a controller design through dynamic analysis, the control characteristics of the wheeled blimp system have been found and finally the stable control system has been successfully developed. The effectiveness of the controller is verified by experiment for the real wheeled blimp system.

• Korean Management Science Review
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• v.13 no.2
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• pp.95-126
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• 1996

Information technology's potential for changing processes is widely acknowledged and various information technologies exist as a tool making business reengineering possible. Groupware is one of information technology that typically work in concert to bring out change in processes. This paper attempts to explain the importance of groupware as a critical information technology for business reengineering by developing a methodology of applying groupware to business reengineering. In order to understand the applicability of groupware to business reengineering, this paper has the following objectives. 1) Examines how the capability of groupware can play as a chang lever or enabler of process innovation explicitly. 2) Propose a integrated business reengineering methodology that incorporates process, process environment and information technologies specifically. A case study was used to provide the insight how groupware can play as a enabler of process innovation. The case was analyzed according to the reengineering methodology we proposed.

• International Journal of Automotive Technology
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• v.5 no.2
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• pp.95-108
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• 2004

Lanekeeping assistance has the potential to save thousands of lives every year by preventing accidental road departure. This paper presents experimental validation of a potential field lanekeeping assistance system with quantitative performance guarantees. The lanekeeping system is implemented on a 1997 Corvette modified for steer-by-wire capability. With no mechanical connection between the hand wheel and road wheels the lanekeeping system can add steering inputs independently from the driver. Implementation of the lanekeeping system uses a novel combination of a multi-antenna Global Positioning System (GPS) and precision road maps. Preliminary experimental data shows that this control scheme performs extremely well for driver assistance and closely matches simulation results, verifying previous theoretical guarantees for safety. These results also motivate future work which will focus on interaction with the driver.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.41-49
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• 2007

More diversified and strengthened safety regulations require higher safety vehicle with less weight. The structural foam can play a role for restraining section distortion of main body members undergoing bending collapse at vehicle crash. In this study, using structural foam modeling technology, validated in previous work, the bending collapse characteristics were evaluated for two types of circular and actual vehicle body frame sections. With changing the foam filling method, outer panel thickness and section shape, load carrying capability and absorbed energy were observed. The results indicate valuable design strategy for effectively elevating bending collapse performance of body members with foam filled.

• Structural Engineering and Mechanics
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• v.56 no.1
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• pp.1-25
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• 2015

The main goal of this study was to develop a convenient strengthening technique for retrofitting of reinforced concrete members. For this purpose a new retrofitting material so-called prefabricated-HSPRCC (high performance steel plate reinforced cementitious composite) panel was developed by using high performance concrete and perforated steel plate. Prefabricated-HSPRCC composes advantages of steel and high performance concrete. The prefabricated-HSPRCC panels were either only bonded on the specimens using epoxy mortar or anchored to the specimen by steel bolts as well as bonding. Effect of different variations such as prefabricated-HSPRCC panel thicknesses, steel plate thicknesses, puncture orientation of perforated steel plate, existence of anchorage etc. were studied through a simple experimental work. The behaviour of the specimens under vertical point load was also studied by using simple mechanics. The retrofitted specimens were found to exhibit much better performance both in terms of strength and deformation capability. The anchorage application was found to positively affect this improved performance. Furthermore, as a result of the tests the best parameters of prefabricated-HSPRCC plate for improving strength and deformation capacities were determined.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.3
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• pp.62-74
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• 1994

This paper addresses on the model synthesis and performance analysis of an engine mount featuring electro-rheological(ER) fluids which undergo a phase change when subjected to electric fields. A novel type of ER fluid-filled engine mount is devised and its hydraulic model is constructed. An equivalent mechanical model is subsequently obtained from the governing equation of the hydraulic model. The model parameters associated with the ER fluids are distilled from experimental investigations on the Bingham properties of the fluids. The distilled data are then incorporated into the governing model to undertake feasible work through computer simulations,. It is shown that the proposed engine mount has an inherent capability of controlling both the damping force and the resonance frequency. Other superior performance characteristics accrued from the proposed methodology are also evaluated.