• Journal of agriculture & life science
• /
• v.45 no.3
• /
• pp.89-96
• /
• 2011

The objective of this study is to evaluate reduction efficiency of various air purifiers on airborne microorganism causing air infected animal disease according to sample collection method. Collection efficiencies of MS2 virus and Pseudomonas fluorescens by biosampler was significantly higher than those by button sampler (p<0.05). Regardless of types of air purifier and sample collection method, temporal reduction efficiencies of MS2 virus and P. fluorescens compared to initial background concentration were >50% and >45% on 5 minutes, >70% and >50% on 15 minutes, >80% and >70% on 30 minutes and >90% and >75% on 60 minutes after operating air purifier, respectively. The air purifier of ionizer type showed the highest reduction efficiency on MS2 virus followed by air purifier of electronic precipitation, water filter and dry filter while the reduction efficiency of air purifier on P. fluorescens was highest in the electronic precipitation type followed by ionizer type, dry filter type and water filter type (p<0.05). Based on the results obtained from this study, temporal reduction efficiency of air purifier on MS2 virus was relatively higher than P. fluorescens.

• Korean Journal of Optics and Photonics
• /
• v.19 no.4
• /
• pp.287-293
• /
• 2008

The collimator which makes a collimated beam, is an essential instrument for assembly and evaluation of telescopes. Recently, the Cassegrain type collimator has been widely used for its compact size as the focal length of high resolution cameras becomes longer. However, this kind of collimator has a disadvantage in that the secondary mirror is a heat source which can degrade the evaluation accuracy for an IR camera system. In this paper, we present the fabrication and measurement process for an off-axis parabolic mirror with the physical diameter pf 1 m, effective diameter 930 mm, and the focal length 6 m. After four months of works we obtained the final surface wave-front error of 30.4 nm rms ($\lambda$/138, ${\lambda}=4.2\;{\mu}m$), which is capable of evaluation of an IR camera as well as a visible camera.

• Science of Emotion and Sensibility
• /
• v.25 no.1
• /
• pp.67-78
• /
• 2022

Interest in bio-signal monitoring of wearable devices is increasing significantly as the next generation needs to develop new devices to dominate the global market of the information and communication technology industry. Accordingly, this research developed a resistive textile strain sensor through a wetting process in a single-wall carbon nanotube dispersion solution using an E-Band with low hysteresis. To measure the resistance signal in the E-Band to which electrical conductivity is applied, a universal material tester, an Arduino, and LCR meters that are microcontroller units were used to measure the resistance change according to the tensile change. To effectively handle various noises generated due to the characteristics of the fabric textile strain sensor, the filter performance of the sensor was evaluated using the moving average filter, Savitsky-Golay filter, and intermediate filters of signal processing. As a result, the reliability of the filtering result of the moving average filter was at least 89.82% with a maximum of 97.87%, and moving average filtering was suitable as the noise filtering method of the textile strain sensor.

• Membrane Journal
• /
• v.33 no.4
• /
• pp.222-232
• /
• 2023

In this study, a hollow fiber support membrane was prepared by a non-solvent induced phase separation (NIPS) method using a polysulfone (PSf). The prepared hollow fiber support membrane was coated with PDMS and Pebax to prepare a hollow fiber composite membrane. The prepared composite membrane was measured for permeance and selectivity for pure CO₂, H₂, O₂ and N₂. Gas separation performance of the module having the highest selectivity (CO₂/H₂) among the prepared composite membrane modules was measured according to the change in stage cut using simulated gas. The composition of the simulated gas used at this time was 70% CO₂ and 30% H₂. In the 1 stage experiment, it was possible to obtain values of about 60% of H₂ concentration and 12% of H₂ recovery. In order to overcome the low H₂ concentration and recovery, 2 stage serial test was performed, and through this, it was possible to achieve 70% H₂ concentration and 70% recovery. Through this, it was possible to derive a separation process configuration for CO₂/H₂ separation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.28 no.1
• /
• pp.41-50
• /
• 2023

Dissolved oxygen sensors have characteristics in which data drift occurs over time. Therefore, in-situ calibration of the dissolved oxygen sensor is essential to accurately measure the concentration of dissolved oxygen in seawater. In order to provide a method for in-situ calibration, appropriate number of samples for calibration, and laboratory calibration interval of the dissolved oxygen sensor, the dissolved oxygen sensor values were compared with the measured values by titration on a total of 133 samples from three different cruises in the Indian Ocean, Pacific Ocean, and East Sea over a period of about one year. As a result, it is preferable to calibrate the sensor value using the correlation of a straight line obtained by directly comparing the final concentration value given by the sensor and the measured value. For the accurate calibration, at least 30 samples must be used to enable in-situ calibration within an accuracy range of about 1%. In addition, it is recommended that a laboratory calibration should perform within 1 year for the membrane type dissolved oxygen sensor for CTD to achieve a performance of 70% or more.

• The Journal of the Convergence on Culture Technology
• /
• v.10 no.1
• /
• pp.585-590
• /
• 2024

In this study, rail surface defects are increasing due to the aging of urban railway rails, but in the detailed guidelines for track performance evaluation established by the country, rail surface damage is inspected with the naked eye of engineers and simple measuring tools. With the recent enactment of the Track Diagnosis Act, a large budget has been invested and the volume of rail diagnosis is rapidly increasing, but it is difficult to secure the reliability of diagnosis results using labor-intensive visual inspection techniques. It is very important to discover defects in the rail surface through periodic track tours and visual inspection. However, evaluating the severity of defects on the rail surface based on the subjective judgment of the inspector has significant limitations in predicting damage inside the rail. In this study, the rail internal crack characteristics due to rail surface damage were studied. In field measurements, rail surface damage locations were selected, samples of various damage types were collected, and the rail surface damage status was evaluated. In indoor testing, we intend to analyze the correlation between rail surface defects and internal defects using a electron scanning microscope (SEM). To determine the crack growth rate of urban railway rails currently in use, the Gaussian probability density function was applied and analyzed.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.20 no.1
• /
• pp.47-51
• /
• 2016

Purpose By ingestion of 18F-FDG of kidney of PET/CT during the inspection, if additional examination is required, depending on whether you want to water intake, we want to confirm a change in the rate of decrease of F-18 FDG of the kidney. Materials and Methods The 80 patients without kidney disease were performed PET/CT examination. Device was analyzed after setting the kidney to a three-dimensional region of interest. In patients require additional examination, and inspection after 30 minutes, a PET/CT torso examination after the water of the 500 cc ingested at a time. After the addition of both water intake group and no hydration group of kidney of SUV, it was compared with PET/CT torso scan. Results High and low of the kidney SUV did not show a significant difference in the rate of decrease. Reduction rates of background (BKG) of additional examination was 2.8% and reduction rates of SUV was 49.7% (Hydration) : -6.8% (No hydration), so did show a significant difference. In the image blind test, the average point score of hydration and no hydration was 34.25 : 17.25. Conclusion An undercurrent of 18F-FDG in the kidney at the time of torso examination, it was confirmed that the reduction rate after the addition of water intake is high. It is considered that can be expected to improve the quality of an image due to a decrease in elongation through the kidneys examination with additional fluid intake as needed intake.

• Korean Chemical Engineering Research
• /
• v.45 no.2
• /
• pp.160-165
• /
• 2007

The synthesis and the characterization of Low Silica X (LSX) zeolite for nitrogen adsorption have been studied. The performance of LSX zeolite for nitrogen adsorption was compared to that of the commercial zeolite. The $Na_2O/(Na_2O+K_2O)$ ratio in the gel and the crystallization time were fixed as the synthetic factor. The LSX zeolite was formed at the $Na_2O/(Na_2O+K_2O)$ ratio of 0.75. The formation of LSX zeolite was confirmed by XRD and SEM. The Si/Al ratio was investigated by using XRF and FT-IR. The synthesized LSX zeolite showed a lower Si/Al ratio than the NaY and NaX zeolites although they have a same faujasite structure. The Si/Al ratio of the LSX zeolite converged close to 1. 1A (Li, Na, K) and 2A (Mg, Ca, Ba) group elements were ion-exchanged to the LSX zeolite. As the charge density of cation rises, the amount of nitrogen adsorbed increased. $Li^+$ ion-exchanged LSX zeolite showed the highest nitrogen adsorption weight. When the Li/Al ratio was over 0.65, nitrogen adsorption increased remarkably. $Li^+$ ions located on the supercage (site III, III') in the LSX zeolite played a role as nitrogen adsorption sites. When the $Ca^{2+}$ ions were added to the LiLSX zeolite by ion-exchange method, the performance for nitrogen adsorption increased more. The performance for the nitrogen adsorption was the highest at the Ca/Al ratio of 0.26. Nitrogen adsorption capacity of LiCaLSX (Ca/Al=0.26) zeolite was superior to the commercial NaX zeolite.

• Radiation Oncology Journal
• /
• v.18 no.4
• /
• pp.337-344
• /
• 2000

Purpose :To design and test test CT simulator phantom for geometrical test. Materials and Methods : The PMMA phantom was designed as a cylinder which is 20 cm in diameter and 24 cm in length, along with a 25$\times25\times31cm^{3}$ rectangular parallelepiped. Radio-opaque wires of which diameter is 0.8 mm are attached on the other surface of the phantom as a spiral. The rectangular phantom was made of four 24$\times24\times0.5 cm^{3}$ square plates and each plate had a 24$\times24 cm^{2}$, 12$\times12cm^{2}$, 6$\times6 cm$^{2}$ square line. The squares were placed to face the cylinder at angles 0 $^{\circ}$ , 15 $^{\circ}$ , 30 $^{\circ}$ ,respectively. The rectangular phantom made it possible to measure the field size, couch angle, the collimator angle, the isocenter shift and the SSD, the measurements of the gantry angle from the cylindrical part. A virtual simulation software, AcOSim, offered various conditions to perform virtual simulations and these results were used to perform the geometrical Quality assurance of CT simulator. Results : A 0.3$\~$0.5 mm difference was found on the 24 cm field size which was created with the DRR measurements obtained by scanning of the rectangular phantom. The isocenter shift, the collimator rotation, the couch rotation, and the gantry rotation test showed 0.5$\~$1 mm, 0.5$\~$l$^{\circ}$ 0.5$\~$ 1$^{\circ}$ , and 0.5-1 $^{\circ}$ differences, respectively. We could not find any significant differences between the results from the two scanning methods. Conclusion :The geometrical test phantom developed in the study showed less than 1 mm (or 1 $^{\circ}$ ) differences. The phantom could be used as a routine geometrical QC/QA tools, since the differences are within clinically acceptable ranges.

• Journal of IKEEE
• /
• v.23 no.4
• /
• pp.1461-1464
• /
• 2019

In this paper, we propose the development of embedded board for integrated radiation exposure protection fireman's life-saving alarm capable of location tracking and radiation measurement. The proposed techniques consist of signal processing unit, communication unit, power unit, main control unit. Signal processing units apply shielding design, noise reduction technology and electromagnetic wave subtraction technology. The communication unit is designed to communicate using the wifi method. In the main control unit, power consumption is reduced to a minimum, and a high performance system is formed through small, high density and low heat generation. The proposed techniques are equipment operated by exposure to poor conditions, such as disaster and fire sites, so they are designed and manufactured for external appearance considering waterproof and thermal endurance. The proposed techniques were tested by an authorized testing agency to determine the effectiveness of embedded board. The waterproof grade has achieved the IP67 rating, which can maintain stable performance even when flooded with water at the disaster site due to the nature of the fireman's equipment. The operating temperature was measured in the range of -10℃ to 50℃ to cope with a wide range of environmental changes at the disaster site. The battery life was measured to be available 144 hours after a single charge to cope with emergency disasters such as a collapse accident. The maximum communication distance, including the PCB, was measured to operate at 54.2 meters, a range wider than the existing 50 meters, at a straight line with the command-and-control vehicle in the event of a disaster. Therefore, the effectiveness of embedded board for embedded board for integrated radiation exposure protection fireman's life-saving alarm has been demonstrated.