• Journal of Sensor Science and Technology
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• v.18 no.5
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• pp.365-371
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• 2009

In this study, we have fabricated a fiber-optic pH sensor which is composed of a light source, plastic optical fibers and a spectrometer. As an indicator, a phenol red is used, and a pH liquid solution is prepared by mixing of phenol red and various kinds of pH buffer solutions in these experiments. The emitting light from a light source is guided by plastic optical fibers to the pH liquid solution, and the optical characteristic of a light is changed in the pH liquid solution according to its color change. Therefore, we have measured the intensities and wavelength shifts of the modulated lights, which are changed due to the color variations of phenol red at different pH values, by using of a spectrometer for spectral analysis. Also, the relationships between the pH values of liquid solutions and the optical properties of modulated light according to the change of color of phenol red are obtained.

• Journal of Sensor Science and Technology
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• v.25 no.2
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• pp.103-109
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• 2016

Recent light-enhanced metal oxide gas sensors are reviewed in this article. The basic mechanisms of a light-enhanced metal oxide gas sensor are discussed. Many literatures reveal that the standalone sensitivity and the response/recovery time enhancements enabled by the exposing light are not as high as the performance enhancement provided by external heating. Therefore, both optimal amount of external heating and exposed light intensity are necessary to increase the performance of these light-enhanced gas sensors. The development of highly light sensitive materials and structures is important to lower the overall power consumptions of the sensors.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.145-150
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• 2015

We introduce a new method of time-division visible light communication (VLC) using LED lamp light for the generation of synchronizing pulses. The LED lamp, driven by an AC 220-V power line, radiates light that has a 120-Hz frequency component. The pulse generator in each VLC system receives the LED lamp light and generates the synchronizing pulses that are required for time-division transmission of multiple VLC channels. The pulse period is subdivided into several time slots for VLC channels. In experiments, 120-Hz synchronizing pulses were generated using LED lamp light, and three VLC channels were transmitted independently without interfering with each other in a condition where the VLC signals overlapped in space. This configuration is useful in constructing multiple wireless sensor networks that are safe and without interference in locations where LED lamps are used for illumination.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.315-319
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• 2021

Recent impact of 4th industrial revolution is increasing usage of IoT technology along with smartphones and tablet PC. However blue light emitted from electronic devices such as smartphones and tablet PC causes detrimental change to human bodies. As the controversy over the harmfulness of blue light became known through the media and various communities, related markets were formed, and various blocking films, software, and vision protection monitors were released. In this paper focuses on utilizing IoT technology to protect human organizations from blue light. It presents anti-blue light system which prevents excessive exposure to blue light through Arduino module such as ultrasound, piezo buzzer and blue light measurement module.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1513-1518
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• 2012

This paper is implemented media transmission system of VLC transmitter and receiver module using LED of White lighting that is based on PC module and to transmission technology for performance analysis. To realize LED visible light communication receiver is used 1~12 LED light-emitting device and transmitter is used a variable sensor. Developed initial distance of the tranceiver is more than 0~1m for LED VLC and the overall system transmission speed is achieved on variable having Visible light media transmission system. Composition to PC module with LED module and infrared sensor for performance analysis, predict and analyze the communication distance, check about the possibility of application methods. Measure each performance when the lens wearing and not wearing in order to increase the overall efficiency of the LED module, can know that increase efficiency of approximately 20%.

• Journal of Power System Engineering
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• v.8 no.3
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• pp.52-57
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• 2004

A new non-destructive inspection technique has been developed. One characteristic of the technique is that defects are visualized by laser ray. Magnetic domains and domain walls of a magneto-optical sensor(MO sensor) are varied by the magnetic flux leaked by defects, and the variations are observed by the reflected light of the laser ray. The information of defect can remotely be inspected by this technique in a real time. This paper describes the results estimated on the 2-dimensional surface defects and opposite-side defects in a ferromagnetic material and the natural surface defect in a clutch disk wheel. The light region of a visible image and the magnitude of a reflected light increases as the input current of the magnetizer increases. The natural surface defect, that has not the width of crack's open mouth, can be also visualized like as 2-dimensional artificial defects.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.583-585
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• 2004

In this paper we will deal with a calibration method for low cost motion capture system using psd(position sensitive detection) optical sensor. To measure the incident direction of the light from LED emitted marker, the PSD is used the output current ratio on the electrode of PSD is proportional with the incident position of the light focused by lens. In order to defect the direction of the light, the current output is converted into digital voltage value by opamp circuits peak detector and AD converter with the digital value the incident position is measured. Unfortunately, due to the non-linearly problem of the circuit poor position accuracy is shown. To overcome such problems, we compensated the non-linearly by using least-square fitting method. After compensated the non-linearly in the circuit, the system showed more enhanced position accuracy.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.133-142
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• 1999

We introduce the algorithms of 2-D and 3-D position estimation using 2-D vision sensors. The sensors used in this research issue red laser slit light to the body. So, it is very convenient to obtain the coordinates of corner point or edge in sensor coordinate. Since the measured points are normally not fixed in the body coordinate, the additional conditions, that corner lines or edges are straight and fixed in the body coordinate, are used to find out the position and orientation of the body. In the case of 2-D motional body, we can find the solution analytically. But in the case of 3-D motional body, linearization technique and least mean squares method are used because of hard nonlinearity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.134-137
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• 2010

An LED sensor luminaire for visual function improvement necessitates the control algorithm for light level adjustment and the appropriate lens design. The control algorithm adapts to surround lighting condition, and thus has the advantages of energy saving and glare reduction. The multi-cell lens design improves color temperature uniformity and spatial light distribution of the luminaire. Experimental and simulated results show that this approach contributes noticeably to energy saving and color temperature uniformity of the LED sensor luminaire.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.98-105
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• 2008

In this paper, the system for monitoring process of aluminum laser welding was developed using the light signal emitted from the plasma which comes from interaction between material and laser. Photodiode for monitoring system was selected based on the spectrum analysis of light from plasma and keyhole. Behavior of plasma and keyhole was analyzed through the sensor signals. Value of sensor signal represented the light intensity and fluctuation of signal indicated the stability of plasma and keyhole. For the relation between welding condition and sensor signals, the input power and weld geometry greatly effected on the average of each sensor signals. Using the feature values of signals, estimation model for tensile strength of weld was formulated with neural network algorithm. Performance of this model was verified through coefficient of determination and average error rate.