• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1423-1426
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• 2005

Map building is the most important thing for the mobile robots navigation. It requires specific vision system such as CCD camera, range finding system, and many other things. Laser range finder has highly collimated beams can be obtained easily, thus achieving lateral resolution. Laser Diode is used for a continuous laser source. The Automatic Current Control Circuit and the Bias-T is used for mix AC signal with DC bias. This signal is used for driving Laser Diode. The main idea of the calculating distance is detecting phase shift between reference signal and detected signal by photo detector. For the signal processing, the Lock-in amplifier system is addressed in this paper. We used a diffused reflected beam to detect phase shift in this system. But this beam is minuteness signal so it can be easily buried in nose. Lock-in amplifier is used to measure the amplitude and phase of signals which are buried in noise.

• Steel and Composite Structures
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• v.6 no.6
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• pp.493-512
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• 2006

The present paper summarizes the experimental research carried out at the "Politehnica" University of Timisoara, Romania, with the scope of investigating the influence of different column web stiffening solutions on the performance of beam-to-column joints of Moment Resisting Steel Frames. The response parameters, such as resistance, rigidity and ductility were examined. Five different types of panel web stiffening were compared with regard to a reference test. A quasi-linear relationship between the moment capacity and the total shear area of the web panel was observed from the experimental tests while the initial rigidity increased non-proportionally with the same area. Comparisons are presented of the experimental tests with the mathematical model developed by Krawinkler and with the model stipulated in Eurocode 3 Part 1.8. These comparisons showed a generally good agreement in the case of moment capacity, while the computed rigidities were always greater than the experimental rigidities.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.353-356
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• 2002

Planar laser induced fluorescence(PLIF) has been widely used to obtain two dimensional fuel distribution. Preliminary investigation was performed to measure quantitative air excess ratio distribution in an engine fueled with LPG. It is known that fluorescence signal from acetone as a fluorescent tracer is less sensitive to oxygen quenching than other dopants. Acetone was excited by KrF excimer laser (248nm) and its fluorescence image was acquired by ICCD camera with a cut-of filter to suppress Mie scattering from the laser light. For the purpose of quantifying PLIF signal, an image processing method including the correction of laser sheet beam profile was suggested. Raw images were divided by each intensity of laser energy and profile of laser sheet beam. Inhomogeneous fluorescence images scaled with the reference data, which was taken by a calibration process, were converted to air excess ratio distribution. This investigation showed instantaneous quantitative measurement of planar air excess ratio distribution for gaseous fuel.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.1
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• pp.54-58
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• 2008

Time reversal (TR) of body waves in fluids and isotropic solids has been used in many applications including ultrasonic NDE. However, the study of the TR method for anisotropic materials is not well established. In this paper, the full reconstruction of the input signal is investigated for anisotropic media using an analytical formulation, called a modular Gaussian beam (MGB) model. The time reversal operation of this model in the frequency domain is done by taking the complex conjugate of the Gaussian amplitude and phase received at the TR mirror position. A narrowband reference signal having a particular frequency and number of cycles is then multiplied and the whole signal is inverse Fourier transformed. The original input signal is seen to be fully restored by the TR process of MGB model and this model can be more generalized to simulate the spatial and temporal focusing effects due to TR process in anisotropic materials.

• International journal of advanced smart convergence
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• v.2 no.1
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• pp.21-23
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• 2013

The antenna pattern in this case has a main beam pointed in the desired signal direction, and has a null in the direction of the interference.The conventional antenna pattern concepts of beam width, side lobes, and main beams are not used, as the antenna weights are designed to achieve a set performance criterion such as maximization of the output SNR.A new direction of arrival estimation method using effects of model errors and sensitivity analysis is proposed. Two subspaces are used to form a signal space whose phase shift between the reference signal and its effects of model error signal. Through simulation, the performance showed that the proposed method leads to increased resolution and improved accuracy of DOA estimation relative to those achieved with existing method. Since a desired signal is obtained after interference rejection through correction effects of model error, the effect of channel interference on the estimation is significantly reduced.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.8
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• pp.392-399
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• 2001

This paper presents an auxiliary beam-assisted adaptive compensation technique applied to alleviate the problem of LDV's body vibration. The LMS algorithm is applied to adaptively compensate the body vibration utilizing the reference signal provided by the auxiliary beam. The usefulness of the proposed technique is verified via computer simulations performed for diverse types of target signals and body vibration.

• Journal of the Optical Society of Korea
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• v.15 no.2
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• pp.111-117
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• 2011

Full-range spectral domain optical coherence tomography (SD-OCT) with a 1-${\mu}m$ band light source is shown here. The phase of the reference beam is continuously stepped while the probing beam scans the sample laterally (B-scan). The two dimensional spectral interferogram obtained is processed by a Fourier transform method to obtain a complex spectrum leading to a full-range OCT image. A detailed mathematical explanation of the complex conjugate resolving method utilized is provided. The system's measurement speed was 7.96 kHz, the measured axial resolution was $9.6{\mu}m$ in air and the maximum sensitivity 99.4 dB. To demonstrate the effect of mirror image elimination, In vivo human eye pathology was measured.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.274-281
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• 1995

The new method of recording and reconstructing a synthetic object, which was called as scannedobject holography (SOH), was proposed and its feasibility was demonstrated theoretically and experimentally. The hologram was recorded by interfering the fixed reference beam with spherical waves emitting from a moving point source, whose trajectory determined the shape of the synthetic object to be recorded. The end face of an optical fiber and the output from a pulsed laser were utilized in order to implement a moving point source experimentally. tally.

• Transactions of the Society of Information Storage Systems
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• v.3 no.1
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• pp.13-16
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• 2007

The purpose of this paper is real time tilt servo control of the holographic data storage system. Holographic data storage device is a next generation data storage device with high storage density, high transfer rate and short access time. This device is very sensitive to a disturbance due to the enormous storage density. As to the recording material changed disc type, the media continuously vibrates as the disc rotates. When disc rotates, deviation, eccentricity and unbalance disturbance are occurred. This disturbances cause disc tilt, finally reference beam does not illuminates to correct incidence angle. Therefore real time tilt servo control is essential. In this paper, the algorithm is proposed to make real time tilt detection in angle multiplexing of the holographic data storage system with an additional servo beam and the experiments are performed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.2
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• pp.161-169
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• 2002

Based on the analytic expression for the elasto-dynamic behavior of rotating shaft, the transfer matrix is formulated for the shaft element with uniform cross-section. Timoshenko beam theory is Introduced for modeling the behavior of shaft. Complex variables representing the displacement, slope, moment and shear force are used for deriving the transfer matrix between both ends of the shaft element. Simulation result obtained by applying the transfer matrix to a general rotor model is compared with the reference result and proved to be exact. Natural frequencies and the corresponding modes are analyzed with varying the bearing: stiffness. The generally used bearings are considered for discussions. and the bearing stiffness is shown to affect the vibration characteristics of rotor.