• Korean Journal of Optics and Photonics
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• v.31 no.3
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• pp.134-141
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• 2020

Optical three-dimensional (3D) measurement systems based on digital fringe projection are used in many contactless measurement applications. The system which can measure a dozen micrometers uses a liquid-crystal display (LCD) as the projection unit for generating a digital fringe pattern, because a flexible fringe pattern can be easily made by computer software. According to the gamma nonlinearity of the LCD projection unit, the digital fringe projection error on the object affects the accuracy of 3D object measurement. An improved method of LCD gamma-nonlinearity error reduction is proposed, by using the inverse function of the intensity transfer function to improve the accuracy. The improvement due to the proposed method is shown by measuring the difference in precision between a computer-generated sine wave and a camera-obtained sine wave for a standard semiconductor specimen.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1990.10a
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• pp.35-40
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• 1990

Temperature distribution of high pressure mercury lamp has been mesured as a function of time using spectroscopic method. Sampling signal which is synchronized by lamp voltage was used to mesure temporal line intensity at each radius. To obtain radial temprature distribution, the mesured intensity was transformed into radial line intensity by Abel's formula. Absolute temperature profile was calculater from relative intensities of spectral lines as a function of line and tube radius. The temperature profile is very similar to the electrical tube current profile.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.388-391
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• 2004

A sol-gel fiber-optic biosensor with encapsulated pH-sensitive fluorophore and immobilized genetically modified toluene-o-xylene monooxygenase was developed to detect TCE and PCE, which are carcinogenic chlorinate organic compounds prevailing in ground water. The sensitivity was characterized for the composition of sol-gel, and manufacturing procedure. The intensity curve reveals a linear range of intensity for pollutant concentration range of 0.01ppm and 1ppm. The change in intensity was appeared to be larger at each of L for same condition, and, therefore, the wavelength of λ was chosen for the analytical measurement.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1157-1159
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• 2003

The effect of the scan velocity modulation is studied. The effect of the velocity modulation on the picture image is judged from the intensity profile of the image. The intensity profile is obtained as time integral of moving Gaussian beam. To confirm the applicability of this integral formula, the measurement and simulation data is compared. And by calculating the intensity profile for different amounts of velocity modulation, the optimum modulation displacement that gives the best image quality is obtained. This optimum modulation displacement can be used in designing scan velocity modulation system.

• Journal of the Korean Society of Combustion
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• v.1 no.1
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• pp.75-82
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• 1996

Laser induced incandescence, LII, recently developed technique for measuring soot concentration in flames, can overcome most of limitations of conventional laser extinction measurement. In this study, experiments were performed to investigate the effect of laser intensity, detection wavelength, and also laser beam quality on both LII signal at a particular position and peak-to-centerline LII signal ratio. The results of LII signal with increasing laser intensity shows its near-independence of laser intensity once threshold level of laser intensity has been reached. However, this near-independence depends on laser beam quality and the incident optical setup. The peak-to-centerline LII signal ratio slowly but continuously increases with laser power. This fact is due to the dependence of LII signal on particle mean diameter. LII signal is attenuated during it passes through the flame containing soot particles. The attenuation rate is inversely proportional to detection wavelength. In this study, LII signal at 680 nm band is 10% greater than the signal at 400 nm band.

• Journal of the Korean Institute of Telematics and Electronics
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• v.8 no.6
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• pp.1-7
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• 1971

This paper describes concerning the method of measurement for the intensity of ultrasonics in liquid. The probe which is added two sensive point of thermocople which is surrounded by the absorbed material of sonic wave on the both side of the refleftite plate have measured the intensity of ultrasonics indirectly by the difference of the temperature of two sensive point which had raised the temperature by the sonic wave and its reflective wave which transmitted the ultrasonic energy. This minify the influence from the temparature of liquid and time constant. Consequently, this is the basic industrial method which is with in the bounds of possibility on the simple measurement of the intensity of the local ultrasonics concerning direction of its propagation.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.525-528
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• 2002

The objective of this study is to investigate characteristics of flow by the Rod shape and the choice of the turbulent intensity enhancement section. The Rod was setup vertically to the way of a nozzle exit flow and nozzle diameter is 17mm. Rod height is 5mm and its shapes are square, triangle, and circle. Characteristics of fluid such as velocity vector distribution, kinetic energy, turbulent intensity, and etc. were visualized, observed, and considered at 3 kinds of Re No. such as 2000, 3000, and 4000. The characteristics of flow field were investigated in each case of the distance rate from the nozzle exit to impinging plate(H/B=8, 10). The temperature of water is $20^{\circ}E$ and the measurement region divided by 3 sections(I, II, III). The nozzle diameter is 17mm. As the experimental result by PIV measurement, scale of the vector profile showed a tendency to an unbalance parabola distribution as increasing of the Re No. When the impinging plates such as square, triangle, and circle shape are installed respectively in front of the flow accelerated, rod shape of the highest velocity vector is circle shape and rod shape of the highest turbulent Intensity is square shape.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1540-1548
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• 2000

Sound intensity techniques and ODS(Operational Deflection Shape) techniques are applied to identify the acoustic noise source of a hard disk drive and its control system. The sound intensity is used to visualize the noise source locations, and the ODS information to visualize the vibration pattern and to obtain the dynamic characteristics of the noise sources. The measurement systems are customized to accurately measure the sound intensity and ODS distributions of HDD system in space domains as well as frequency domains. The measurement systems for the sound absorption and transmission loss of materials are also used to support the background data for the efficient noise control. Using the visual information of source locations and its dynamic characteristics, the partial noise barrier structure and optimum absorption are designed and its controlled sound power level is proved to be under 3.1 Bel(Idle)/3.3Bel (Seek) which is the lowest level in the disk drive industry.

• Journal of Sensor Science and Technology
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• v.32 no.5
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• pp.267-274
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• 2023

LiDAR, one of the most important sensing methods used in mobile robots and cars with assistive/autonomous driving functions, is used to locate surrounding obstacles or to build maps. For real-time path generation, the detection of potholes or puddles on the driving surface is crucial. To achieve this, we used the coordinates of the reflection points provided by LiDAR as well as the intensity information to classify water areas, which was achieved by applying a linear regression method to the intensity distribution. The rationale for using the LiDAR index as an input variable for linear regression is presented, and we demonstrated that it is not affected by errors in the distance measurement value. Because of LiDAR vertical scanning, if the reflective surface is not uniform, it is divided into different groups according to the intensity distribution, and a mathematical basis for this is presented. Through experiments in an outdoor driving area, we could distinguish between flat ground, potholes, and puddles, and kinematic analysis was performed to calculate the maximum width that could be crossed for a given vehicle body size and wheel radius.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.91-94
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• 2012

Arrayed waveguide grating (AWG) phase errors are normally assessed from the Fourier transform of the interference intensity data in the frequency domain method. However it is possible to identify the phases directly from the intensity data if one adopts a trial-and-error method. Since the functional form of the intensity profile is known, the intensities can be calculated theoretically by assuming arbitrary phase errors. Then we decide the phases that give the best fit to the experimental data. We verified this method by a simulation. We calculated the intensities for an artificial AWG which is given arbitrary phases and amplitudes. Then we extracted the phases and amplitudes from the intensity data by using our trial-and-error method. The extracted values are in good agreement with the originally given values. This approach yields better results than the analysis using Fourier transforms.