• 한국항공우주학회지
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• 제31권5호
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• pp.63-71
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• 2003

본 논문에서는 몸체진동형 링레이저 자이로에서 몸체진동을 검출하기 위한 각속도 센서 출력을 V-F 변환하여 링레이저 출력에서 몸체진동에 의한 출력을 제거하는 dither-stripping 방법에 대하여 논의하였다. Dither-stripping에서는 V-F 출력펄스와 링레이저 출력펄스간의 환산계수를 산출하는 방법과 V-F 출력펄스의 offset를 보정해주는 방법이 중요하다. 각속도 센서의 출력을 V-F 변환하여 dither-stripping하는 경우에는 offset을 보정하는 과정에서 몸체진동의 진폭잡음에 의한 자이로 출력의 오차가 크게 발생한다. 우리는 V-F 출력펄스를 미분하여 offset을 제거하는 방법을 고안하였다. 이를 위해서는 각속도 센서의 출력을 90deg 위상 이동시켜서 각도신호를 만들고 V-F 변환해야 하며 링레이저 출력의 위상도 샘플링의 반주기만큼 이동시켜야 한다. 그리고 두 펄스간의 환산계수는 분산을 이용하여 산출하였다. 이러한 각도신호 미분방식의 dither-stripping에 의하여 개선된 결과를 얻을 수 있었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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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.

• 중환자간호학회지
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• 제8권1호
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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.

• 한국분말재료학회지
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• 제15권5호
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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.

• 한국분말재료학회지
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• 제19권4호
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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.

• 한국도로학회논문집
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• 제18권6호
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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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• 제29권3호
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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.

• 대한원격탐사학회지
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• 제37권2호
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• pp.359-365
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• 2021

천리안위성2A호 기상탑재체 AMI(Advanced Meteorological Imager) 센서 검출기의 최상의 요소들로 구성된 Best Detector Select (BDS) 맵은 발사 전 확정되어 AMI에 업로드 되어 있다. 위성 발사 이후 급격한 온도 변화 환경에 노출되면 검출기의 성능에 변화가 생길 수 있으며, 발사 및 탑재체 아웃개싱 이후에 BDS맵의 성능을 다시 분석하고 필요시 업데이트가 필요하다. 검출기 요소 전체에 대한 성능을 검증하기 위한 분석 작업이 탑재체 개발업체(미 L3HARRIS사)가 제공한 BDS맵 분석 기술 문서를 기반으로 진행되었다. BDS맵 분석이란 탑재체 검출기가 기준 목표물(심우주와 탑재체 내부 보정 타겟)을 응시하는 동안 얼마나 안정적인 신호를 보이는 지를 평가하는 것이다. 이러한 목적으로 LTS(Long Time Series) 및 V-V(Output Voltage vs. Bias Voltage)라 부르는 검증법이 이용된다. LTS는 30초 동안, V-V는 2초 동안 목표물을 응시하고 이 때의 검출기 노이즈 성분을 계산한다. 자료를 획득하기 위해서는 탑재체의 운영을 멈추고 특별 관측을 실시하여야 하기 때문에, 정상 운영 전인 궤도상 시험기간 중에 해당 작업이 이루어지게 된다. 천리안위성2A호 기상탑재체 궤도상 시험 기간 동안 획득한 자료를 바탕으로 BDS맵의 상태를 평가하였다. 발사 전 지상 시험에서 평가된 BDS맵의 전체 성분들 중에 약 1%에 해당하는 요소들이 성능 변화를 보였으며, 이를 다른 요소들 중 최상의 성능을 보이는 성분으로 교체하였다. 새로운 BDS맵을 적용한 결과 BDS문제로 인해 야기된 기상탑재체 원시영상에 나타나는 노이즈 성분(줄무늬)이 완전하게 제거되었다.