• Journal of Positioning, Navigation, and Timing
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• v.12 no.1
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• pp.67-73
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• 2023

As interest in underwater structures and ocean exploration increases, many researchers are proposing methods for modeling and controlling various remotely operated vehicles (ROVs). Recently, hybrid systems composed of an autonomous underwater vehicle and an ROV capable of remote control and autonomous navigation are being developed. In this study we introduce a method that models Ariari-aROV, an ROV consisting of five thrusters, and performs navigation. The proposed ROV can be controlled manually and by autonomous navigation when given a target point. An extended Kalman filter is utilized for sensor measurement correction for more precise navigation. The proposed method is verified through a simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2382-2386
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• 2003

The Global Positioning System(GPS) is a satellite based precise positioning system avaliable worldwide. The GPS have many error sources. The earth's ionosphere and atmosphere cause delays in the GPS signal that translate into position errors. Some errors can be factored out using mathematics and modeling. The configuration of the satellites in the sky can magnify other errors. The problem of accuracy on GPS measurement data can be meaningful. In this study, we propose the method for GPS positioning accuracy improvement. The FUZZY set theory on PDOP(Position Dilution of Precision) and SNR(Signal to Noise Ratio) provide improved for measured positioning data. The accuracy of positioning has been improved by selecting data from original using the FUZZY set theory on PDOP and SNR.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.772-775
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• 2005

Most engineers, related to soil and civil dynamic field, have been interested in the direct dynamic design of building transmitted from soil and rock to structure due to blasting. However it is not easy to estimate the dynamic response of structures due to blasting by using analytical method because of difficulties of soil modeling, prediction of excitation force and so on. In this paper, dynamic analysis have been performed to predict vibration level and evaluate dynamic safety of structure adjacent to tunnel blast and the semi empirical method, which is based on vibration measurement data, has been employed to consider blast vibration characteristics.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2516-2520
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• 2005

In this paper, finite impulse response (FIR) smoothers are proposed for discrete-time systems. The proposed FIR smoother is designed under the constraints of linearity, unbiasedness, FIR structure, and independence of the initial state information. It is also obtained by directly minimizing the performance criterion with unbiased constraints. The approach to the MVF smoother proposed in this paper is logical and systematic, while existing results have heuristic assumption, such as infinite covariance of the initial state. Additionally, the proposed MVF smoother is based on the general system model that may have the singular system matrix and has both system and measurement noises. Thorough simulation studies, it is shown that the proposed MVF smoother is more robust against modeling uncertainties numerical errors than fixed-lag Kalman smoother which is infinite impulse response (IIR) type estimator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.431-434
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• 2004

The design, simulation, modeling and measurement of a RF switch module for GSM applications were presented in this paper. switch module were simulated by ADS and constructed using a LTCC multi-layer switching circuit and integrated low pass filter, designed to operate in the GSM band. Insertion and return losses at 900 MHz of the low pass filters were designed to lower than 0.3 dB and higher than 12.7 dB respectively. The switch module constructed, contained 10 embedded passives and 3 surface mounted components integrated on $4.6{\times}4.8{\times}1.2$ m volume, 6-layer integrated circuit. The insertion loss of switch module at m MHz were around 11 dB.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.419-424
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• 1996

As track density increases, the effects of nonlinearity in pivot bearing of hard disk drive on the servo performance are becoming more important in considering the range of inertia force and the input torque during settling and tracking mode. Recently, an increasing attention is given to more precise experimental observations and modelings of pivot nonlinearity for achieving higher performance of servo control. In this paper, we propose a new model that shows an improved prediction of the pivot nonlinearity than existing preload-plus-two-slope model at matching simulations and experimental results in both time and frequency domains. Experimental measurements are carried out to validate and identify the specific nonlinearity presents in the pivot bearing when its in fine motion. Using the experimental results new model along with the existing one are characterized and compared for relevancies.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.10
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• pp.1751-1768
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• 2011

Falls are one of the most concerned accidents for elderly people and often result in serious physical and psychological consequences. Many researchers have studied fall detection techniques in various domain, however none released to a commercial product satisfying user requirements. We present a systematic modeling and evaluating procedure for best classification performance and then do experiments for comparing the performance of six procedures to get a statistical classifier based wrist-type fall detector to prevent dangerous consequences from falls. Even though the wrist may be the most difficult measurement location on the body to discern a fall event, the proposed feature deduction process and fall classification procedures shows positive results by using data sets of fall and general activity as two classes.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.2
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• pp.178-184
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• 2002

This paper deals with the transfer alignment problem of SDINS(StrapDown Inertial Navigation System) subjected to roll and pitch motions of the ship. In order to reduce alignment errors induced by ship body flexure, a linearized error model for the velocity and attitude matching transfer alignment system is first derived by linearizing the nonlinear measurement equation with respect to the dominant y axis component and defining the flexure state of random constant type. And then a robust state estimation scheme is introduced to account for modeling uncertainty of the flexure. By interpreting the simulation results and comparing with the velocity and DCM(Direction Cosine Matrix) partial matching method, it is shown that the proposed method is effective enough to improve the azimuth alignment performance.

• Transactions on Electrical and Electronic Materials
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• v.6 no.2
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• pp.39-45
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• 2005

Numerical and visualization procedures are used in a finite difference grid to analyze and better understand the heat transfer in the MEMS based air micro-jet array (MIA) impingement cooling device. The Navier-Stokes (NS) equations with incompressible flow are solved using an implicit procedure. The temperature contour and velocity vector visualization diagrams are used for illustration. The computed temperature distribution at the bottom of the MIA is in good agreement with the experimental measurement data. The parameters are investigated to improve the efficiency of heat transfer in the MIA. The optimum configuration of the MIA is suggested. The present modeling explains the flow phenomenon and yields valuable information to understand the flow and heat transfer in MIA.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.567-574
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• 2013

An optical model is proposed in the white LED using phosphor and LED chip. In this paper a new model that describes the absorption rate and quantum efficiency with increasing the mixing ratio of phosphor in silicone, and the allotment of the phosphor absorption optical power in the several phosphor mixing in the silicone. Single phosphor in silicone from the optical measurement data before and after molding, the solution to get the blue optical power and the phosphor emission optical power is proposed. By these solution the absorption rate and the quantum efficiency was obtained. The model with single phosphor mixing in the silicone the validity was confirmed.