• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.5
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• pp.967-974
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• 2024

This paper propose a method for detecting defects in 3D printer outputs using a transmissive photo sensor. The transmissive photo sensor measures the transmittance of the material and is used to detect defects that may occur during the printing process. To this end, the transmissive photo sensor is integrated into the 3D printer platform, and an algorithm that processes the data obtained from the sensor in real time to judge the presence of defects was developed. The results of the experiment confirmed that the propoesd system can quickly detect a variety of defects that occur during the manufacturing process. Not only can these results play a crucial role in quality control and productivity enhancement of 3D printers, but they also have potential for application in the manufacturing industry. In the future, it is expected that the defect detection system based on the proposed method will improve the stability and efficiency fo the manufacturing process.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.562-565
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• 1996

The photoreactivity of twelve anthraquinone derivatives was examined to evaluate its usefulness as a photo-reagent for the analysis of ginsenosides using photoreduction fluorescence (PRF) detection method. Among the tested compounds, 2-tert-butylandthraquinone (TBAQ), 2-chloroanthraquinone (CAQ) and anthraquinone (AQ) showed good characteristics as photoreagents. The detection limits of ginsenoside $Rg_{1}$PRF-HPLC method using TBAQ, CAQ or AQ as a photo-reagent were found to be ca. 35 ng, 50 ng and 50 ng, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.354-359
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• 1994

On-line process control equipment for CO $_{2}$ laser cutting is unavailable for industrial application. The major part of the industrial cutting machines are regulated off-line by highly educated engineers. The quality inspection of the sample is visual and referred to different quality scales. Due to lack of automation potential laser users hesitate to implement the cutting method. The first step toward an automation of the process is development of a process monitoring system and the research is concentrated on the area of on-line quality detection during CO $_{2}$ laser cutting. The method bases on the detection of the emitted light from the cut front by photo diode. the signal from photo diode has been undertaken from Fourier analysis and statistical analysis. As a result, it is possible to estimate striation pattern according to beam travel speed.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.252-253
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• 2002

원적외선 영역에서 혈중성분들의 분광 특성이 존재함이 확인되면서 이 영역의 빛을 이용한 혈중 성분의 정량 분석을 통한 진단기술 개발이 활발히 진행되고 있다1). 특히 원적외선 영역에서 특정 파장에서의 반응성을 이용한 여러 방법들 중 photo-Acoustic을 이용한 방법이 여러 가지로 연구되어지고 있다. (2) 현재 수용액 상태의 혈중 성분들의 원적외선 분광 특성을 연구하였으며, 이를 이용한 혼합 성분들의 흡수 spectrum 정량-정성 분석이 가능하며, 이러한 특성을 이용하여 non-invasive로 이용 가능한 분광법을 연구 진행 중이다. (중략)

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.85-89
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• 2004

This paper represents the development of high sensitivity photo-sensor for the fluorescence detection in the integrated biological analysis system. The finger-type PIN photodiodes were fabricated as the photo-sensor, and had a high sensitivity ($I_{light}/I_{dark}$ = 8720). The interference filter consisted of $TiO_{2}$ and $SiO_{2}$ was directly deposited on the photodiodes. Deposited filter with 95.5% reflection under 532 nm and 98% transmission over 580 nm exceedingly decreased the magnitude of background signal in the detection. The PDMS micro-fluidic channels are bonded on the photodiode by $O_{2}$ plasma treatment. The detection current was proportional to two primary parameters (light intensity, concentration), and the on-chip detection system could detect fluorescence signals down to 100 nM concentration (LOD = Limit of detection of rhodamine).

• Journal of Sensor Science and Technology
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• v.21 no.5
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• pp.339-344
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• 2012

This article describes a novel method for the detection of amyloid-${\beta}$($A{\beta}$) peptide that utilizes a photo-sensitive field-effect transistor (p-FET). According to a recent study, $A{\beta}$ protein has been known to play a central role in the pathogenesis of Alzheimer's disease (AD). Accordingly, we investigated the variation of photo current generated from p-FET with and without intracellular magnetic beads conjugated with $A{\beta}$ peptides, which are placed on the p-FET sensing areas. The decrease of photo current was observed due to the presence of the magnetic beads on the channel region. Moreover, a similar characteristic was shown when the Raw 264 cells take in magnetic beads treated with $A{\beta}$ peptide. This means that it is possible to simply detect a certain protein using magnetic beads and a p-FET device. Therefore, in this paper, we suggest that our method could detect tiny amounts of $A{\beta}$ for early diagnosis of AD using the p-FET devices.

• Journal of Sensor Science and Technology
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• v.15 no.2
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• pp.112-119
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• 2006

Resolution of an image sensor is very significant parameter to improve. It is hard to improve the resolution of the CMOS vision chip for edge detection based on a biological retina using a resistive network because the vision chip contains additional circuits such as a resistive network and some processing circuits comparing with general image sensors such as CMOS image sensor (CIS). In this paper, we proved the problem of low resolution by separating photo-sensing and signal processing circuits. This type of vision chips occurs a problem of low operation speed because the signal processing circuits should be commonly used in a row of the photo-sensors. The low speed problem of operation was proved by using a reset decoder. A vision chip for edge detection with $128{\times}128$ pixel array has been designed and fabricated by using $0.35{\mu}m$ 2-poly 4-metal CMOS technology. The fabricated chip was integrated with optical lens as a camera system and investigated with real image. By using this chip, we could achieved sufficient edge images for real application.

• Tunnel and Underground Space
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• v.20 no.3
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• pp.207-216
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• 2010

Rockfall monitoring systems generally used in the country are mainly based on the detection of tension of protection wire or tilting of protection post due to rock fall. However, rock fall protection net must be installed prior to the monitoring system and continual maintenance work after each rock fall event is required for a normal operation of these detection systems. To solve these problems, we suggested and implemented a non-contact rock fall detection system using multiple photo sensors and additional camera. After a laboratory experiment and field application, we can conclude that this system is effective and reliable for detecting, collecting and analyzing the rock fall information. In addition, lighten and difference operations on two captured images were able to yield rough estimation of size and direction of rock fall.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.100-103
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• 2003

Signal detection technologies such as fluorescence, charge and electrochemical detection used in the monolithic capillary electrophoresis system to convert the biochemical reaction into the electrical signal. The fluorescence detection using photodiodes that measure fluorescence emitted from eluting molecules is widely used for the monolithic capillary electrophoresis system. In this paper, in order to fabricate a photosensor has the increased sensitivity, we investigated on the sensitivity of general type and p-i-n type diode. The p-i-n diode has higher sensitivity than photodiode. Considering these results, we fabricated p-i-n diodes on the high resistive$(4k{\Omega}{\cdot}cm)$ wafer into rectangle and finger pattern and compared internal resistance of each pattern. The internal resistance of p-i-n diode can be decreased by the application of finger pattern has parallel resistance structure from $571{\Omega}$ to $393{\Omega}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.377-377
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• 2007

A simplified integration process including packaging is presented, which enables the realization of the portable fluorescence detection system. A fluorescence detection microchip system consisting of an integrated PIN photodiode, an organic light emitting diode (OLED) as the light source, an interference filter, and a microchannel was developed. The on-chip fluorescence detector fabricated by poly(dimethylsiloxane) (PDMS)-based packaging had thin-film structure. A silicon-based integrated PIN photo diode combined with an optical filter removed the background noise, which was produced by an excitation source, on the same substrate. The active area of the finger-type PIN photo diode was extended to obtain a higher detection sensitivity of fluorescence. The sensitivity and the limit of detection (LOD S/N = 3) of the system were $0.198\;nA/{\mu}M$ and $10\;{\mu}M$, respectively.