• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.5
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• pp.63-71
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• 2003

In this paper we dicuss the dither-stripping methods by V-F(voltage to frequency) conversion of the output of angular velocity sensor which is for detecting the dither motion of the ring laser cavity. In this case, it is very important to evaluate the pulse-to-pulse scale factor between the ring lase output pulse and V-F output pulse, and also to compensate the zero offset of the V-F output pulse. In the case of the dither-stripping by the V-F conversion of angular velocity sensor output, there is a big angle uncertainty in the process of compensating the zero offset due to the dither noise for compensating the V-F output. By differential, the phase of the V-F output is changed. So, to compensate it, we change 90deg of the phase of angular velocity sensor output and delay half sampling time of the phase of ring laser output in advance. In this case the pulse-to-pulse scale factor can be evaluated by the standard deviation of each pulse. We can get the good result of the dither-stripping output by this angle differential method.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.694-696
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• 2003

The KOMPSAT/OSMI remote sending data of 800 km swath are collected by whisk broom method employing 96 charge coupled devices (CCDs). The stripping noise in the OSMI imageries, which arise mainly due to the non-uniform sensitivities of 96 CCDs, are the major hindrance for oceanographic applications of the OSMI data. The OSMI images are corrected by 'Ensemble Smoothness' method which is based on an assumption that the series of the averages and variances of digital numbers in each line should vary smoothly. The data of each line are corrected by linear regression model of which coefficients are obtained by Ensemble Smoothness method. Our algorithm can be applied not only to OSMI data but also for other remote sensing date collected by whisk broom or push broom.

• Journal of Korean Critical Care Nursing
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• v.8 no.1
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• pp.41-49
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• 2015

Purpose: The purpose of this study was to measure the noise levels in intensive care units (ICUs) and to analyze the causes of the noise and patient perceptions of the noise. Methods: Noise levels were recorded in adult ICUs for 24 h over a week from the patients' bedside with a sound level meter. Noise sources were categorized into three groups: medical equipment, health care providers, and the environment. Noises from the environment were recorded in an empty ICUs side room. Perceptions of the noise of 125 patients admitted to the ICUs were recorded using a questionnaire. Results: The mean level of noise in the ICUs was 58.5 dBA (range: 34.2-80.2 dBA). The causes of noise higher than 70 dBA were nebulizers and infusion/syringe pumps among medical equipment, and drawer slamming, phone ringing, and stripping packages of medical fluids among environmental noises. According to the questionnaire, 64.0% of the patients responded that the ICUs were noisy and that they suffered from sleep disturbance because of the noise. Conclusion: Noise is considerably high in ICUs and is an annoying factor for the patients. Most noise sources are adjustable, and we should try to reduce noise whenever possible to make the ICUs environment more pleasant.

• Journal of Powder Materials
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• v.15 no.5
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• pp.393-398
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• 2008

Trace analysis of Cd and Pb at surface modified thick film graphite electrode with Bi nanopowder has been carried out using square-wave anodic stripping voltammetry (SWASV) technique. Bi nanopowder synthesized by gas condensation (GC) method showed the size of $50{\sim}100$ nm with BET surface area, $A_{BET}=6.8m^{2}g^{-l}$. For a strong adhesion of the Bi nanopowder onto the screen printed carbon paste electrode, nafion solution was added into Bi-containing suspension. From the SWASV, it was found that the Bi nanopowder electrode exhibited a well-defined responses relating to the oxidations of Cd and Pb. The current peak intensity increased with increasing concentration of Cd and Pb. From the linear relationship between Cd/Pb concentrations and peak current, the sensitivity of the Bi nanopowder electrode was quantitatively estimated. The detection limit of the electrode was estimated to be $0.15{\mu}g/l$ and $0.07{\mu}g/l$ for Cd and Pb, respectively, on the basis of the signal-to-noise characteristics (S/N=3) of the response for the $1.0{\mu}g/l$ solution under a 10 min accumulation.

• Journal of Powder Materials
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• v.19 no.4
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• pp.297-303
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• 2012

In this study, voltammetry system for realizing high sensitivity nano-labeled sensor of detecting heavy metals was designed, and optimal system operating conditions were determined. High precision digital to analog converter (DAC) circuit was designed to control applied unit voltage at working electrode and analog to digital converter (ADC) circuit was designed to measure the current range of $0.1{\sim}1000{\mu}A$ at counter electrode. Main control unit (MCU) circuit for controlling voltammetry system with 150 MHz clock speed, main memory circuit for the mathematical operation processing of the measured current value and independent power circuit for analog/digital circuit parts to reduce various noise were designed. From result of voltammetry system operation, oxidation current peaks which are proportional to the concentrations of Zn, Cd and Pb ions were found at each oxidation potential with high precision.

• International Journal of Highway Engineering
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• v.18 no.6
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• pp.123-130
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• 2016

OBJECTIVES : The objective of this research is to determine the moisture resistance of the freeze-thaw process occurring in low-noise porous pavement using either hydrated-lime or anti-freezing agent. Various additives were applied to low-noise porous asphalt, which is actively paved in South Korea, to overcome its disadvantages. Moreover, the optimum contents of hydrated-lime and anti-freezing agent and behavior properties of low-noise porous asphalt layer are determined using dynamic moduli via the freeze-thaw test. METHODS : The low-noise porous asphalt mixtures were made using gyratory compacters to investigate its properties with either hydrated-lime or anti-freezing agent. To determine the dynamic moduli of each mixture, impact resonance test was conducted. The applied standard for the freeze-thaw test of asphalt mixture is ASTM D 6857. The freeze-thaw and impact resonance tests were performed twice at each stage. The behavior properties were defined using finite element method, which was performed using the dynamic modulus data obtained from the freeze-thaw test and resonance frequencies obtained from non-destructive impact test. RESULTS : The results show that the coherence and strength of the low-noise porous asphalt mixture decreased continuously with the increase in the temperature of the mixture. The dynamic modulus of the normal low-noise porous asphalt mixture dramatically decreased after one cycle of freezing and thawing stages, which is more than that of other mixtures containing additives. The damage rate was higher when the freeze-thaw test was repeated. CONCLUSIONS : From the root mean squared error (RMSE) and mean percentage error (MPE) analyses, the addition rates of 1.5% hydrated-lime and 0.5% anti-freezing agent resulted in the strongest mixture having the highest moisture resistance compared to other specimens with each additive in 1 cycle freeze-thaw test. Moreover, the freeze-thaw resistance significantly improved when a hydrated-lime content of 0.5% was applied for the two cycles of the freeze-thaw test. Hence, the optimum contents of both hydrated-lime and anti-freezing agent are 0.5%.

• Toxicological Research
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• v.29 no.3
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• pp.211-215
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• 2013

The trace toxic metal copper was assayed using mercury immobilized on a carbon nanotube electrode (MCW), with a graphite counter and a reference electrode. In this study, a macro-scale convection motor was interfaced with a MCW three-electrode system, in which a handmade MCW was optimized using cyclic- and square-wave stripping voltammetry. An analytical electrolyte for tap water was used instead of an expensive acid or base ionic solution. Under these conditions, optimum parameters were 0.09 V amplitude, 40 Hz frequency, 0.01 V incremental potential, and a 60-s accumulation time. A diagnostic working curve was obtained from 50.0 to 350 ${\mu}g/L$. At a constant Cu(II) concentration of 10.0 ${\mu}g/L$, the statistical relative standard deviation was 1.78% (RSD, n = 15), the analytical accumulation time was only 60 s, and the analytical detection limit approached 4.6 ${\mu}g/L$ (signal/noise = 3). The results were applied to non-treated drinking water. The content of the analyzed copper using 9.0 and 4.0 ${\mu}g/L$ standards were 8.68 ${\mu}g/L$ and 3.96 ${\mu}g/L$; statistical values $R^2$ = 0.9987 and $R^2$ = 0.9534, respectively. This method is applicable to biological diagnostics or food surveys.

• Korean Journal of Remote Sensing
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• v.37 no.2
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• pp.359-365
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• 2021

GEO-KOMPSAT-2A (GK2A) AMI (Advanced Meteorological Imager) Best Detector Select (BDS) map is pre-determined and uploaded before the satellite launch. After the launch, there is some possibility of a detector performance change driven by an abrupt temperature variation and thus the status of BDS map needs to be evaluated and updated if necessary. To investigate performance of entire elements of the detectors, AMI BDS analyses were conducted based on a technical note provided from the AMI vendor (L3HARRIS). The concept of the BDS analysis is to investigate the stability of signals from detectors while they are staring at targets (deep space and internal calibration target). For this purpose, Long Time Series (LTS) and Output Voltage vs. Bias Voltage (V-V) methods are used. The LTS for 30 secs and the V-V for two secs are spanned respectively for looking at the targets to compute noise components of detectors. To get the necessary data sets, these activities were conducted during the In-Orbit Test (IOT) period since a normal operation of AMI is stopped and special mission plans are commanded. With collected data sets during the GK2A IOT, AMI BDS map was intensively examined. It was found that about 1% of entire detector elements, which were evaluated at the ground test, showed characteristic changes and those degraded elements are replaced by alternative best ones. The stripping effects on AMI raw images due to the BDS problem were clearly removed when the new BDS map was applied.