• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.8
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• pp.27-33
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• 2001

The performance of the ordinary Fiber Bragg Grating(FBG) sensor strain measurement system, which uses Fabry-Perot filter for scanning wavelength, has limitation for application because of hysteresis characteristics of PZT element in the filter, slow scan rate of the filter and the high cost of system. We proposed and experimented a multiple FBG sensor system using light emitting diode(LED) as a light source and adapting Code Division Multiplexing(CDM) method to separating out individual sensor signal. Output signals for a applied static and dynamic strain and crosstalk levels between sensor signals were measured. The price of the system is very loss and the response speed is very fast. Crosstalk levels between sensor signals below - 30 dB were demonstrated.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.834-837
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• 2005

In this paper, we describe the method of non-invasive blood pressure measurement using pulse wave transit time(PWTT). PWTT is a new parameter involved with a vascular that can indicate the change of BP. PWTT is measured by continuous monitoring of ECG and pulse wave. No additional sensors or modules are required. In many cases, the change of PWTT correlates with the change of BP. We measure pulse wave using the photo plethysmograph(PPG) sensor in an earlobe and we measure ECG using the ECG monitoring device our made in the chest. The measurement device for detecting pulse wave consists of infrared LED for transmitted light illumination, pin photodiode as light detector, amplifier and filter. We composed 0.5Hz high pass, 60Hz notch and 10Hz low pass filter. ECG measurement device consists of multiplexer, amplifier, filter, micro-controller and RF module. After amplification and filtering, ECG signal and pulse wave is fed through micro-controller. We performed the initial work towards the development of ambulatory BP monitoring system using PWTT. An earlobe is suitable place to measure PPG signal without the restraint in daily work. From the results, we can know that the dependence of PWTT on BP is almost linear and it is possible to monitoring an individual BP continuously after the individual calibration.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.1-7
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• 2004

This study has been numerically conducted to investigate the removal efficiency of Volatile Organic Compound (VOC) for different photocatalytic honeycomb filters. Recently, the photocatalysis is being applied to air-cleaner, air-conditioner and vacuum-cleaner with the capability of air-purification, sterilization and antibiosis. However, photocatalysis is less efficient than other methods for removing VOC except in the case of low concentration. So far most of studies have focused on an improvement of the photocatalytic materials, but this study have placed emphasis on the improvements of shape of photocatalytic honeycomb filter. UV irradiation, concentration profile and pressure drop have been investigated for different cross sections of filters and for different filter lengths. Light intensity is dropped sharply with increasing distance from the UV-lamp, and becomes very low in the middle of the filters. Since photocatalytic reaction rate is a function of light intensity, VOC concentration gradient might be small in the middle of long filters. Thus, most of reaction have risen within only three times of dimensionless axial distance. These results can be used effectively for the design of advanced photocatalytic honeycomb filters.

• 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).

• Korean Journal of Food Science and Technology
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• v.13 no.2
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• pp.114-120
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• 1981

A rapid and simple method for detecting colors was attempted on the basis of absorption and emission spectra of reflected light at $45^{\circ}$ angle from color-adsorbed filter paper illuminated by ultraviolet light through interference filter. Absorption spectra of prepared samples revealed more characteristic patterns than emission spectra. Detection of colors was readily accomplished by the investigation of wave length range, distribution pattern, the number of absorption bands and the degree of quenching.

• Journal of Sensor Science and Technology
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• v.30 no.1
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• pp.56-60
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• 2021

In this study, the relationship between the transmitted light intensity and full-width-at-half-maximum (FWHM) of a Fabry-Perot filter was investigated. The measured refractive indices and absorption coefficients of the fabricated thin films were applied to the Fabry-Perot filter via simulations using optical software. Although considerable research has been conducted on Fabry-Perot filters, this study focused on the usefulness of 4.26-㎛ infrared filtering in carbon dioxide detection. Optical analysis was performed considering the effects of the thickness, refractive indices, and number of thin films in a distributed Bragg reflector. Ultimately, a clear trade-off relationship was observed wherein the transmitted light intensity decreased as the number of multilayers increased; however, the FWHM was observed to be narrower.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.5
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• pp.494-499
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• 2023

In this paper, in order to apply the CF (color filter) type of the micro light emitting device (Micro LED) display method, a study on the manufacturing process of red and green phosphor inks for the inkjet process was conducted. The blue light-emitting KSF and LuAG phosphors were respectively used to control the phosphor particle size to about 1㎛, and a phosphor ink was prepared by synthesizing with a low-viscosity solution (IPA/Eg). A chemical dispersion method was applied to selectively control the dispersion characteristics in the manufacture of phosphor inks, and in particular, phosphor inks with a dispersant applied a dispersant secured stable dispersion characteristic compared to phosphor inks without a dispersion process. Therefore, it seems possible to manufacture CF for Micro LED through an inkjet process capable of controlling the dispersion characteristics of phosphor ink.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.4
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• pp.330-336
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• 1996

An real-time active beacon localization system for mobile robots is developed and implemented. This system permits the estimation of robot positions when detecting light sources by PSD(Position Sensitive Detector) sensor which are placed sparsely over the robots work space as beacons(or landmarks). An LSE(Least Square Estimation) method is introduced to calibrate the internal parameters of a model for the beacon and robot position. The proposed system has two operational modes of position estimation. One is the initial position calculation by the detection of two or more light sources positions of which are known. The other is the continuous position compensation that calculates the position and heading of the robot using the IEKF(Iterated Extended Kalman Filter) applied to the beacon and dead-reckoning data. Practical experiments show that the estimated position obtained by this system is precise enough to be useful for the navigation of robots.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.916-919
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• 1996

An real-time active beacon localization system for mobile robots is developed and implemented. This system permits the estimation of robot positions when detecting light sources by PSD(Position Sensitive Detector) sensor which are placed sparsely over the robot's work space as beacons(or landmarks). An LSE(Least Square Estimation) method is introduced to calibrate the internal parameters of a model for the beacon and robot position. The proposed system has two operational modes of position estimation. One is the initial position calculation by the detection of two or more light sources positions of which are known. The other is the continuous position compensation that calculates the position and heading of the robot using the IEKF(Iterated Extended Kalman Filter) applied to the beacon and dead-reckoning data. Practical experiments show that the estimated position obtained by this system is precise enough to be useful for the navigation of robots.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.37-53
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• 1993

The polynuclear hydrocarbons (PAHs) emitted from coke oven standpipe were sampled using three sampling systems, including glass fiber filter+silver membrane filter, glass fiber filter+silver membrane filter+XAD-2 adsorbent tube, PTFE membrane filter+XAD-2 adsorbent tube, extracted by methylene chloride and analysed by gas chromathography using flame ionization detector. The results of this study were as follows. 1. Because the amounts of coke oven emissions(COE) were large, the analyses of PAHs were simple and possible without evaporation and concentration. Although the generation of COE was high during early stage of coking, the airborne concentration of PAHs was low and increased during late coking. 2. The contents of PAHs in COE were 1.35-2.81%. 3. The index components of PAHs were fluoranthene and pyrene. Their correlation coefficient to total PAHs were 0.96, 0.95, respectively. 4. The particulate PAHs were sampled by filter and gaseous PAHs by adsorbent tube. The collection efficiency of glass fiber filter+silver membrane filter was 20% of total amount sampled by filters+adsorbent and PTFE membrane filter 50%. Adsorbent tube must be attached to the filter to collect light and small PAH components. 5. The generation of acenaphthene and indeno (1,2,3-cd) pyrene were low and concentrations of fluorene and anthracene were $20-40ug/m^3$ throughout coking time. Other PAH eoncentrations were sometimes high. The generation of PAHs was low at 4-6 hours of coking time. The gaseous PAHs were generated earlier than particulate PAHs.