• Title/Summary/Keyword: Calibration Interval

Search Result 97, Processing Time 0.025 seconds

A Study on the Treatment of Uncertainty in Linear Regression Method for Chemical Analysis (회귀식 사용에 따른 화학 분석 과정의 불확도 처리 연구)

  • Woo, Jin-Chun;Suh, JungKee;Lim, MyungChul;Park, MinSu
    • Analytical Science and Technology
    • /
    • v.16 no.3
    • /
    • pp.185-190
    • /
    • 2003
  • We applied modified least square method (MLS) and ordinary least square method (OLS) to 1st order equation for the comparison of the uncertainties calculated by these methods. The uncertainty calculated by OLS covered statistically safe interval because it was over-estimated in many cases of measurement and concentration level. But, if the uncertainty of the concentration as a reference value was comparably large (about 5% of the relative standard deviation of random scattering from the regression line and about 7% of relative standard uncertainty of reference values), then uncertainty calculated by OLS was seriously under-estimated at high concentration level. It was revealed that the calculated uncertainty didn't cover statistically safe interval at the stated confidence level. It was found that the method, MLS, described in the previously article would be valid for this calculation of uncertainty.

Prediction of Venous Trans-Stenotic Pressure Gradient Using Shape Features Derived From Magnetic Resonance Venography in Idiopathic Intracranial Hypertension Patients

  • Chao Ma;Haoyu Zhu;Shikai Liang;Yuzhou Chang;Dapeng Mo;Chuhan Jiang;Yupeng Zhang
    • Korean Journal of Radiology
    • /
    • v.25 no.1
    • /
    • pp.74-85
    • /
    • 2024
  • Objective: Idiopathic intracranial hypertension (IIH) is a condition of unknown etiology associated with venous sinus stenosis. This study aimed to develop a magnetic resonance venography (MRV)-based radiomics model for predicting a high trans-stenotic pressure gradient (TPG) in IIH patients diagnosed with venous sinus stenosis. Materials and Methods: This retrospective study included 105 IIH patients (median age [interquartile range], 35 years [27-42 years]; female:male, 82:23) who underwent MRV and catheter venography complemented by venous manometry. Contrast enhanced-MRV was conducted under 1.5 Tesla system, and the images were reconstructed using a standard algorithm. Shape features were derived from MRV images via the PyRadiomics package and selected by utilizing the least absolute shrinkage and selection operator (LASSO) method. A radiomics score for predicting high TPG (≥ 8 mmHg) in IIH patients was formulated using multivariable logistic regression; its discrimination performance was assessed using the area under the receiver operating characteristic curve (AUROC). A nomogram was constructed by incorporating the radiomics scores and clinical features. Results: Data from 105 patients were randomly divided into two distinct datasets for model training (n = 73; 50 and 23 with and without high TPG, respectively) and testing (n = 32; 22 and 10 with and without high TPG, respectively). Three informative shape features were identified in the training datasets: least axis length, sphericity, and maximum three-dimensional diameter. The radiomics score for predicting high TPG in IIH patients demonstrated an AUROC of 0.906 (95% confidence interval, 0.836-0.976) in the training dataset and 0.877 (95% confidence interval, 0.755-0.999) in the test dataset. The nomogram showed good calibration. Conclusion: Our study presents the feasibility of a novel model for predicting high TPG in IIH patients using radiomics analysis of noninvasive MRV-based shape features. This information may aid clinicians in identifying patients who may benefit from stenting.

Management of Severe Trauma Patients in the Emergency Intensive Care Unit (응급중환자실에서의 중증외상환자 치료)

  • Kim, Ji-Ju;Suh, Gil-Joon;Jeong, Ki-Young;Kwon, Woon-Yong;Kim, Kyung-Su;Lee, Hui-Jai;Kim, Yeong-Cheol;Choi, Seok-Ho;Lee, Young-Ho;Lee, Kyung-Hag;Han, Kook-Nam;Jae, Hwan-Jun;Kim, Hyo-Cheol
    • Journal of Trauma and Injury
    • /
    • v.24 no.2
    • /
    • pp.98-104
    • /
    • 2011
  • Purpose: The aim of this study was to evaluate the quality of the trauma care system of our hospital, in which emergency physicians care for major trauma patients in the emergency intensive care unit (ICU) in consultation with intervention radiologists and surgeons. Methods: This was a retrospective observational study conducted in an emergency ICU of a tertiary referral hospital. We enrolled consecutive patients who had been admitted to our emergency ICU with major trauma from March 2007 to September 2010. We collected data with respect to demographic findings, mechanisms of injury, the trauma and injury severity score (TRISS), emergency surgery, angiographic intervention, and 6-month mortality. Then, we compared the observed and predicted survivals of the patients. The Hosmer-Lemeshow test and calibration plots by using 10 groups, one for each decile, of predicted mortality were used to evaluate the fitness of TRISS. P-values of greater than 0.05 represent a fair calibration. Results: Among 116 patients, 12 (10.34%) were dead within 6 months after admission to the ICU, and 29 (25.00%) and 38 (32.80%) patients received emergency surgery and angiographic intervention, respectively. The mean injury severity score and revised trauma score were $36.97{\pm}17.73$ and $7.84{\pm}6.75$, respectively. The observed survival and the predicted survival of the TRISS were 89.66% (95% confidence interval [CI]: 84.03~95.28%) and 69.85% (95% CI: 63.80~75.91%), respectively. The calibration plots showed that the observed survival of our patients was consistently higher than the predicted survival of the TRISS ($p$ <0.001). Conclusion: The observed survival for the trauma care system of our hospital, in which emergency physicians care for major trauma patients in the emergency ICU in consultation with intervention radiologists and surgeons, was higher than the predicted survival of the TRISS.

Induction of the High Order Calibration Equation of Metal Oxide Semiconductor Gas Sensors (산화물 반도체식 가스센서의 입출력 고차 캘리브레이션 방정식 도출)

  • Park, Gyoutae;Kim, Kangmin;Lee, Hyeonggi;Yoon, Myeongsub
    • Journal of the Korean Institute of Gas
    • /
    • v.24 no.2
    • /
    • pp.44-49
    • /
    • 2020
  • In this paper, a measuring circuit is designed through analyzing manufacture specification of the sensor based on MOS. And the best input-output polynomial are induced that really gas sensors are used in gas safety management industrial fields. Response characteristics of a MOS gas sensor is analysed by through sensor's output voltages are measured after standard gases with six kinds of concentrations are manufactured and are injected to the sensor. A lookup table is created by relations of sensor's output voltages by injecting gases with other concentrations. Because data of the formed lookup table are equal interval, a polynomial can be induced of method of approximation function. So the 5th polynomial of input-output for a sensor is defined, coefficients are calculated by using least squares method, and the 5th polynomial is completed for representing characteristics of the sensor. If the proposed polynomial is applied to gas leak detectors, an inverse transformation of polynomial and programing of array codes are recreated. In this research, polynomial is implemented with array types that intervals of values of a lookup table are one-fifth sampled and interpolated. The performance of proposed 5th calibration equation is verified that errors are reduced than a linear expression when tests are performed by measurement of concentrations against injection of standard gases.

Analysis on Food Waste Compost by Near Infrared Reflectance Spectroscopy(NIRS) (Near Infrared Reflectance Spectroscopy(NIRS)에 의한 음식물 쓰레기 퇴비 분석에 관한 연구)

  • Lee Hyo-Won;Kil Dong-Yong
    • Korean Journal of Organic Agriculture
    • /
    • v.13 no.3
    • /
    • pp.281-289
    • /
    • 2005
  • In order to find out an alternative way of analysis of food waste compost, the Near Infrared Reflectance Spectroscopy(NIRS) was used for the compost assessment because the technics has been known as non-detructive, cost-effective and rapid method. One hundred thirty six compost samples were collected from Incheon food waste compost factory at Namdong Indurial Complex. The samples were analyzed for nitrogen, organic matter (OM), ash, P, and K using Kjedahl, ignition method, and acid extraction with spectrophotometer, respectively. The samples were scanned using FOSS NIRSystem of Model 6500 scanning mono-chromator with wavelength from $400\~2,400nm$ at 2nm interval. Modified partial Least Squares(MPLS) was applied to develop the most reliable calibration model between NIR spectra and sample components such as nitrogen, ash, OM, P, and K. The regression was validated using validation set(n=30). Multiple correlation coefficient($R^2$) and standard error of prediction(SEP) for nitrogen, ash, organic matter, OM/N ratio, P and K were 0.87, 0.06, 0.72, 1.07, 0.68, 1.05, 0.89, 0.31, 0.77, 0.06, and 0.64, 0.07, respectively. The results of this experiment indicates that NIRS is reliable analytical method to assess some components of feed waste compost, also suggests that feasibility of NIRS can be Justified in case of various sample collection around the year.

  • PDF

VALIDATION OF ON-LINE MONITORING TECHNIQUES TO NUCLEAR PLANT DATA

  • Garvey, Jamie;Garvey, Dustin;Seibert, Rebecca;Hines, J. Wesley
    • Nuclear Engineering and Technology
    • /
    • v.39 no.2
    • /
    • pp.133-142
    • /
    • 2007
  • The Electric Power Research Institute (EPRI) demonstrated a method for monitoring the performance of instrument channels in Topical Report (TR) 104965, 'On-Line Monitoring of Instrument Channel Performance.' This paper presents the results of several models originally developed by EPRI to monitor three nuclear plant sensor sets: Pressurizer Level, Reactor Protection System (RPS) Loop A, and Reactor Coolant System (RCS) Loop A Steam Generator (SG) Level. The sensor sets investigated include one redundant sensor model and two non-redundant sensor models. Each model employs an Auto-Associative Kernel Regression (AAKR) model architecture to predict correct sensor behavior. Performance of each of the developed models is evaluated using four metrics: accuracy, auto-sensitivity, cross-sensitivity, and newly developed Error Uncertainty Limit Monitoring (EULM) detectability. The uncertainty estimate for each model is also calculated through two methods: analytic formulas and Monte Carlo estimation. The uncertainty estimates are verified by calculating confidence interval coverages to assure that 95% of the measured data fall within the confidence intervals. The model performance evaluation identified the Pressurizer Level model as acceptable for on-line monitoring (OLM) implementation. The other two models, RPS Loop A and RCS Loop A SG Level, highlight two common problems that occur in model development and evaluation, namely faulty data and poor signal selection

Statistical Analysis on the Temperature Dependence and Long-Term Change of Relative Humidity Sensors (상대습도계의 온도 의존성과 경년변화의 통계적 분석)

  • Kim, Jong Chul;Choi, Byung Il;Woo, Sangbong;Yang, Inseok
    • Journal of Sensor Science and Technology
    • /
    • v.21 no.6
    • /
    • pp.420-424
    • /
    • 2012
  • We have investigated temperature dependence and long-term change of humidity measurement from 32 relative humidity sensors. The readings of the humidity sensors depended not only the reference humidity, but also temperature of the chamber. Approximately, the temperature dependence of the humidity sensor in average was 0.05 %R.H./$^{\circ}C$ in the temperature range from $5^{\circ}C$ to $55^{\circ}C$. For humidity sensors that have an internal temperature compensation circuit, the resulting temperature dependence was weaker by 20%. It should be also noted that for the humidity sensors used in this work underwent ${\pm}3$ %R.H. change per year for level of confidence of 95%. The users of relative humidity sensors may refer this value as a minimum change when they set the calibration interval of the humidity sensors.

Disturbance Effects of Field $V_S$ Probe (현장 전단파 속도 프로브의 교란효과)

  • Yoon, Hyung-Koo;Lee, Chang-Ho;Lee, Woo-Jin;Lee, Jong-Sub
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2008.03a
    • /
    • pp.605-612
    • /
    • 2008
  • The shear wave velocity ($V_s$) has been commonly used to evaluate the dynamic properties of soil. The field $V_s$ probe (FVP) was already developed to assess the shear stiffness of a soft clay. The objective of this study is to investigate the disturbance effects of the FVP due to the penetration. The laboratory tests are conducted in a large-scale consolidometer (calibration chamber). The reconstituted clay is mixed at the water content of 110% using a slurry mixer. The FVP and down-hole test are carried out every 1cm interval to compare the data. In addition, two square rods with transducers are also implemented to get the reference value. The shear waves evaluated by the FVP, dow-hole tests, and reference rods are closely matched. This study suggests that the disturbance effect of the FVP due to the penetration into the soft clay soils is small enough and the $V_s$ evaluated by the FVP reflects well the in-situ characteristics. Furthermore, the combination of the FVP and down-hole test shows the possibility of hybrid equipment.

  • PDF

Assessing sample disturbance of shelby tube using shear waves (전단파를 이용한 쉘비 튜브의 샘플 교란 효과 평가)

  • Yoon, Hyung-Koo;Lee, Jong-Sub;Kim, Joon-Han;Cho, Yong-Soon
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2008.03a
    • /
    • pp.134-141
    • /
    • 2008
  • To evaluate the engineering properties of soil, the laboratory test always is carried out using samples obtained from the field. There are many studies to estimate the effect of sampling disturbance. The objective of this study appraises the disturbance using the shear wave velocity. The new shelby tube which three transducers are installed every 20cm interval is used. To laboratory tests, the large-scale consolidometer (calibration chamber) is used. During 1cm penetration, the shear wave velocity is measured by every transducer. The initial sampling disturbance is assessed through the velocity difference from bottom to right upside transducer. After finishing the sampling, the velocity is still measured every time to assess the soil disturbance in shelby tube itself. Through the measured velocity, the effect of disturbance is appraised. This study suggests that the sampling disturbance of shelby tube is effectively evaluated using shear wave velocity.

  • PDF

SI Engine Closed-loop Spark Advance Control Using Cylinder Pressure (실린더 압력을 이용한 SI엔진의 페루프 점화시기 제어에 관한 연구)

  • Park, Seung-Beom;Yun, Pal-Ju
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.9 s.180
    • /
    • pp.2361-2370
    • /
    • 2000
  • The introduction of inexpensive cylinder pressure sensors provides new opportunities for precise engine control. This paper presents a control strategy of spark advance based upon cylinder pressure of spark ignition engines. A location of peak pressure(LPP) is the major parameter for controlling the spark timing, and also the UP is estimated, using a multi-layer feedforward neural network, which needs only five pressure sensor output voltage samples at -40˚, -20˚, 0˚, 20˚, 40˚ after top dead center. The neural network plays an important role in mitigating the A/D conversion load of an electronic engine controller by increasing the sampling interval from 10 crank angle(CA) to 20˚ CA. A proposed control algorithm does not need a sensor calibration and pegging(bias calculation) procedure because the neural network estimates the UP from the raw sensor output voltage. The estimated LPP can be regarded as a good index for combustion phasing, and can also be used as an MBT control parameter. The feasibility of this methodology is closely examined through steady and transient engine operations to control individual cylinder spark advance. The experimental results have revealed a favorable agreement of individual cylinder optimal combustion phasing.