• Journal of Institute of Control, Robotics and Systems
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• v.12 no.8
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• pp.834-841
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• 2006

Recently, many enterprises are installing AMSs(Automated Manufacturing Systems) for their competitive advantages. As the level of automation increases, proper design and validation of control logic is a imperative task for the successful operation of AMSs. However, current discrete event simulation methods mainly focus on the performance evaluation. As a result, they lack the modeling capabilities for the detail logic of automated manufacturing system controller. Proposed in this paper is a method of validation of the controller logic for automated material handling system using an object-oriented design and simulation. Using this method, FA engineers can validate the controller logic easily in earlier stage of system design, so they can reduce the time for correcting the logic errors and enhance the productivity of control program development Generated simulation model can also be used as a communication tool among FA engineers who have different experiences and disciplines.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2735-2737
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• 2000

In this paper, we deal with modeling and analysis for mobile manipulator systems. In order to avoid the difficulties occurring due to slippage or unevenness of the terrain, we propose the utilization of minimum actuators. In this case, the resulting systems typically possess kinematic redundancies which can be beneficially employed for correcting the position error. A simple PD control method along with kinematic redundancy is employed to recover position errors for trajectory control in task space. Several primary and secondary criteria utilizing kinematic redundancy of the mobile manipulator system are tested through graphic animation.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.628-632
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• 2002

Low voltage circuit breakers which interrupt rapidly and raise the reliability of power supply are widly used in power distribution systems. In the paper, it was investigated how much Interrupting capability was improved by correcting the shape of the contact system in molded case circuit breaker(below MCCB), especially arc runner. Prior to the interrupting testing, it was necessary for the optimum design to analyze electromagnetic forces on the contact system, generated by current and flux density. This paper presents both our compuational analysis and test results on contact system in MCCB

• Journal of Positioning, Navigation, and Timing
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• v.6 no.2
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• pp.59-70
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• 2017

Since GPS signals are vulnerable to interference and obstruction, many alternate aiding systems have been proposed to integrate with an inertial navigation system. Among these alternate systems, the vision-aided method has become more attractive due to its benefits in weight, cost and power consumption. This paper proposes a loosely-coupled vision/INS integrated navigation method which can work in GPS-denied environments. The proposed method improves the navigation accuracy by correcting INS navigation and sensor errors using position and attitude outputs of a landmark based vision navigation system. Furthermore, it has advantage to provide redundant navigation output regardless of INS output. Computer simulations and the van tests have been carried out in order to show validity of the proposed method. The results show that the proposed method works well and gives reliable navigation outputs with better performance.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.109-112
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• 1996

The more integrated and smaller SMD are needed, new solder joints packaging technologies are developed in these days such as BGA(Ball Grid Array), Flip Chip, J-lead etc. But, it's unable to inspect solder joints in those devices by visual inspection methods, because they are hided by it's packages. To inspect those new SMD packages, an X-ray system for acquiring a cross-sectional image of a arbitrary plane is necessary. In this paper, an analysis for designing X-ray cross sectional imaging system is presented including the way for correcting the distortion of image intensifier. And we show computer simulation of that system with a simple PCB model to show it's usefulness in applying PCB solder joint inspection.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.2
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• pp.37-42
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• 2006

In this paper, we study a problem of providing reliable data transmission in wireless sensor network(WSN). A system with forward error correction9FEC) can provide an objective reliability while using less transmission power than a system without FEC. We propose the use of LDPC codes of various code rate (0.53, 0.81, 0.91) of FEC for WSN. Node-node-node interference is considered in the simulation in addition to AWGN in the channel. It is shown that the rate of 0.91 LDPC coded system obtained 7dB gain in signal to noise ratio over a system without FEC.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.47-48
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• 2006

A roughness measuring system which comprises an integrating sphere and a stabilized laser has been fabricated with the aim of measuring the roughness correction value which is necessary in gauge block measurement by optical interferometry. To calibrate the system, a Newton's ring interferometer has been introduced. The method how to calibrate the roughness measurement system has been described.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.132-139
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• 2001

In this research, we have developed a load/unload device capable of correcting the position automatically. Characteristic technologies such as compensation, control, guidance and communication have been modified and implemented on an existing electromagnetic guided AGV, helping to realize open system and distributed cooperation. We have applied the developed AGV with remote control and heterogeneous load/unload mechanisms in a machining system composed of various equipment such as machining centers, CMN and AS/RS and found that the AGV provided position error within $\pm$2mm.

• Journal of electromagnetic engineering and science
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• v.17 no.1
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• pp.39-43
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• 2017

In this paper, a systematic and statistical calibration technique was implemented to calibrate a high-speed signal converting system containing multiple digital-to-analog converters (DACs). The systematic error (especially the imbalance between DACs) in the current combining network of the multi-DAC system was modeled and corrected by calculating the path coefficients for individual DACs with wideband reference signals. Furthermore, by applying a Kalman filter to suppress noise from quantization and clock jitter, accurate coefficients with minimum noise were identified. For correcting an arbitrary waveform generator with two DACs, a co-simulation platform was implemented to estimate the system degradation and its corrected performance. Simulation results showed that after correction with 4.8 Gbps QAM signal, the signal-to-noise-ratio improved by approximately 4.5 dB and the error-vector-magnitude improved from 4.1% to 1.12% over 0.96 GHz bandwidth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.4
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• pp.324-330
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• 1990

In this paper, the hybrid ARQ system involving the single error correcting and double error detection (127, 119) cyclic Hamming codes and the SR(selective repeat) ARQ schemes with a finite receiver buffer has been designed and constructed. The system performance has been analyzed and simulated. As a result of the simulation, it has been shown that the transmitter retransmitted those data blocks that were detected in errors especially the request signal errors using two retransmission. The system performance was measured by throughput efficiency due to channel error effects.