• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.1
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• pp.1-15
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• 1986

Optic flow is 2D velocity projected on the image plane of 3D velocity of a moving surface element. In this paper, we survey techniques computing optic flows from an image time sequence of moving objects and techniques determining 3D velocities and surface structures of the moving objects from the optic flows determined.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1149-1152
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• 1996

Recently visual servo control is an important feature of an intelligent robot system. In this paper, we presents a Kalman filter approach for estimation of the linear optic flow model which is utilized in the visual servoing of a mobile robot. The proposed method is also compared with the conventional least mean square method via computer simulation.

• Physical Therapy Rehabilitation Science
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• v.1 no.1
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• pp.33-39
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• 2012

Objective: The objective of this study is to investigate the effect of treadmill training with real optic flow scene on functional recovery of balance and balance self-efficacy in stroke patients. Design: Single blind, Randomized controlled trial. Methods: Nine patients following stroke were divided randomly into the treadmill with optic flow group (n=3), treadmill with virtual reality group (n=3), and control group (n=3). Subjects in the treadmill with optic flow group wore a head-mounted display in order to receive a speed modulated real optic flow scene during treadmill training for 30 minutes, while those in the treadmill with virtual reality group and control group received treadmill training with virtual reality and regular therapy for the same amount of time, five times per week for a period of three weeks. Timed up and go test (TUG) and activities-specific balance confidence scale (ABC scale) were evaluated before and after the intervention. Results: TUG in the treadmill training with optic flow group showed significantly greater improvement, compared with the treadmill training with virtual reality group and control group (p<0.05). Significantly greater improvement in the ABC scale was observed in the treadmill training with optic flow group and the tread mill training with virtual reality group, compared with the control group (p<0.05). Conclusions: Findings of this study demonstrate that treadmill training with real optic flow scene can be helpful in improving balance and balance self-efficacy of patients with chronic stroke and may be used as a practical adjunct to routine rehabilitation therapy.

• 대한공업교육학회지
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• v.34 no.1
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• pp.274-286
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• 2009

Fiber optic sensor is widely used in measuring acoustic and vibration. Especially interferometric sensors are more suitable to measure the acoustic signal. In this paper, a Fabry-Perot interferometric fiber optic sensor was used to measure flow induced vibration. This vibration also measured using an accelerometer, and the data was compared to one other. The venture, nozzle, drop barrel, and rapid expansion in the pipeline are the measuring objects. The flow rate is changed from 50 L/min to 150 L/min and the average flow velocity was about 7 m/s. Based on the experimental results the suggested fiber optic sensor detects flow induced vibration effectively. Therefore, this kind of fiber optic sensor can be applied to the monitoring the flow induced noise and vibration such as pipelines, cables, buildings.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.451-454
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• 2006

Fiber optic distributed temperature sensing and thermal line sensor are applied in an observation borehole and a loom deep borehole heat exchanger. For the case of permanently installed system fiber optic DTS is very useful. By comparing with TLS, fiber optic DTS shows good accuracy and reliability. Ground water flow can give influences at heat exchange rate of the heat pump system. According to the hydraulic characteristics and temperature-depth profile, we consider that temperature-depth profile do not seem to be dependent on ground water flow. A permanent installation of fiber optic cable is expected as a reliable temperature measurement technique in a borehole heat exchanger system.

• Journal of the Korean Society of Visualization
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• v.11 no.1
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• pp.34-40
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• 2013

Gas/liquid two-phase ejector is a device without moving parts, in which liquid is used to drive gas of a low-pressure source. In this paper, the hydrodynamic characteristics of a vertical down type two-phase ejector were studied using an air-water loop system. Entrained air flow rates were measured with inlet and outlet pressures of the ejector with varying water flow rate. Homogeneous bubbly flows in the discharge pipe were confirmed by the high speed flow visualization method. Quantitative measurements of void fraction were made using a newly developed fiber optic probe system.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.34-36
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• 1990

The flow direction in a glass tube is measured by using a forward scatering dual beam laser Doppler velocimeter with an acousto-optic modulator. We can determine the flow direction by measuring the shifted Doppler frequency which is dependent on the order of modulation of the laser frequency shifting moves only the Doppler signal, enabling complete separation of the Pedestal and Doppler singal.

• Analytical Science and Technology
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• v.8 no.4
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• pp.1101-1108
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• 1995

Acousto-optic tunable filter is a compact, all solid state electronic dispersive device. It is based on the acousto-optic interaction in an anisotropic crystal. Compared to conventional grating monochromators. the AOTF has no moving parts, wider spectral tuning range (from UV through visible and near-IR to IR), higher throughput, higher resolution, faster scanning (${\mu}s$) and random wavelength access. These features make it possible to use the filter to develop novel instruments which are not possible otherwise. The instrument development and unique advantages of such AOTF based instruments including the multidimensional fluorimeter, the multiwavelength thermal lens spectrometer, and the detectors for HPLC and flow injection analysis are described.

• Journal of Ocean Engineering and Technology
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• v.26 no.3
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• pp.61-65
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• 2012

Air-water flow measurements are of importance for the coastal and ocean engineering fields. Although kinematic investigations of the multi-phase flows have been conducted for long time, velocity measurements still are concerned with many researchers and engineers in coastal and ocean areas. In the present study, an imaging technique using shadowgraphy and fiber optic probe for velocity measurements of air bubbles is introduced. The shadow graphy image technique is modified from the typical image velocimetry methods, and optical fibers are used for the well-known intrusive coupled phase-detection probe system. Since the imaging technique is a non-intrusive optical method from the air, it is usually applied for 2D flows. On the other hand, the double fiber optic probes touch flows regardless of flow patterns. The results of the flow measurements by both methods are compared and discussed. The methods are also applied to the measurements of overtopping flows by a breaking wave over the structure fixed on the free surface.

• Korean Journal of Optics and Photonics
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• v.1 no.1
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• pp.58-64
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• 1990

The flow direction in a glass tube is measured by using a forward scattering dual beam laser Doppler velo$.$ cimeter with an acousto-optic modulator. We can determine the flow direction by measuring the shifted Doppler frequency which is dependent on the order of modulation of the laser beam and the fluid flow direction. Also. an electronic amplification circuit which has a bandwidth of 0 . 300 MHz and a gain of 38 dB is designed and fabricated to amplify the high frequency signal.signal.