• Title/Summary/Keyword: Determination of Parameters

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Application of Inference Models for Estimating Parameters of a Catchment Modelling System (추론모델을 통한 강우-유출모형 매개변수의 간접추정법 적용)

  • Choi, Kyung-Sook
    • Journal of Korea Water Resources Association
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    • v.36 no.4
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    • pp.587-596
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    • 2003
  • Application of a catchment modelling system requires recorded information to ascertain the reliability and robustness of the predicted flow conditions. Where this recorded information is not available, the necessary information for reliable and robust predictions must be obtained from other available information sources. The alternative approach presented in this paper used inference models for getting this necessary information that is required to calibrate and validate the catchment modelling system for both an ungauged and a gauged catchments. In this study, inference models were developed for determination of control parameters of the Storm Water Management Model (SWMM), mainly based on landuse component of the catchment, which is a major factor to impact on quantity and quality of catchment runoff. Results from the study show that the new approach for determination of the spatially variable control parameters produced more accurate estimates than a traditional approach. Also, the number of control parameters estimated can be reduced significantly as the proposed method only requires determination of control parameters associated with each land use of the catchment while a traditional approach needs to assign a number of control parameters for a number of subcatchment.

Real-Time Determination of Relative Position Between Satellites Using Laser Ranging

  • Jung, Shinwon;Park, Sang-Young;Park, Han-Earl;Park, Chan-Deok;Kim, Seung-Woo;Jang, Yoon-Soo
    • Journal of Astronomy and Space Sciences
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    • v.29 no.4
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    • pp.351-362
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    • 2012
  • We made a study on real-time determination method for relative position using the laser-measured distance data between satellites. We numerically performed the determination of relative position in accordance with extended Kalman filter algorithm using the vectors obtained through nonlinear equation of relative motion, laser simulator for distance measurement, and attitude determination of chief satellite. Because the spherical parameters of relative distance and direction are used, there occur some changes in precision depending on changes in relative distance when determining the relative position. As a result of simulation, it was possible to determine the relative position with several millimeter-level errors at a distance of 10 km, and sub-millimeter level errors at a distance of 1 km. In addition, we performed the determination of relative position assuming the case that global positioning system data was not received for long hours to see the impact of determination of chief satellite orbit on the determination of relative position. The determination of precise relative position at a long distance carried out in this study can be used for scientific mission using the satellite formation flying.

A Method for Determination of 3D-Electrical Discharge Machining Parameters Using Z-map (Z-map을 이용한 3차원 방전가공조건의 결정방법)

  • 주상윤;이건범
    • Korean Journal of Computational Design and Engineering
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    • v.4 no.4
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    • pp.355-359
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    • 1999
  • This paper presents a method for determining machining parameters in electrical discharge machining process (EDM) based on discharge area. The parameters are the peak value of currents, the pulse-on time, and the pulse-off time, on which the EDM performance depends chiefly. The optimal machining parameters are closely related on discharge area, which can be calculated from a tool electrode and a discharge height. In the paper the discharge area is obtained from NC code for machining the tool electrode instead of its geometric model. The method consists of following three steps. First a Z-Map model is constructed from the NC code. Secondly, the discharge area is obtained from the Z-Map model and a Z-height. Finally, the machining parameters are calculated from the discharge area. An introduced example shows that the machining parameters are calculated by the using a Z-map model obtained from the machining data for a tool electrode.

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Gaussian mixture model for automated tracking of modal parameters of long-span bridge

  • Mao, Jian-Xiao;Wang, Hao;Spencer, Billie F. Jr.
    • Smart Structures and Systems
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    • v.24 no.2
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    • pp.243-256
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    • 2019
  • Determination of the most meaningful structural modes and gaining insight into how these modes evolve are important issues for long-term structural health monitoring of the long-span bridges. To address this issue, modal parameters identified throughout the life of the bridge need to be compared and linked with each other, which is the process of mode tracking. The modal frequencies for a long-span bridge are typically closely-spaced, sensitive to the environment (e.g., temperature, wind, traffic, etc.), which makes the automated tracking of modal parameters a difficult process, often requiring human intervention. Machine learning methods are well-suited for uncovering complex underlying relationships between processes and thus have the potential to realize accurate and automated modal tracking. In this study, Gaussian mixture model (GMM), a popular unsupervised machine learning method, is employed to automatically determine and update baseline modal properties from the identified unlabeled modal parameters. On this foundation, a new mode tracking method is proposed for automated mode tracking for long-span bridges. Firstly, a numerical example for a three-degree-of-freedom system is employed to validate the feasibility of using GMM to automatically determine the baseline modal properties. Subsequently, the field monitoring data of a long-span bridge are utilized to illustrate the practical usage of GMM for automated determination of the baseline list. Finally, the continuously monitoring bridge acceleration data during strong typhoon events are employed to validate the reliability of proposed method in tracking the changing modal parameters. Results show that the proposed method can automatically track the modal parameters in disastrous scenarios and provide valuable references for condition assessment of the bridge structure.

HPLC Method for the Determination of Nicorandil in Human Plasma

  • Park, Sun-Hee;Shin, In-Chul
    • Biomolecules & Therapeutics
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    • v.16 no.2
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    • pp.168-172
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    • 2008
  • The present study is to determine of sensitive nicorandil analysis method using HPLC and measure the pharmacokinetics parameters (bioavailability, $C_{max}$, $T_{max}$, Ke, $T_{1/2}$) of nicorandil (5 mg, Tab; Choongwae Pharma Corporation). Plasma (500 ul) was mixed with furosemide (internal standard, 500 ug/ml). Detection wavelength was 256 nm. The mixture of 0.01 M ammonium acetate and acetonitrile 80:20 (v/v) was used mobile phase. The HPLC separation was accomplished on ODC reverse HPLC column. The nicorandil was analyzed by a HPLC system, which consists of CAPCELL PAK C18 column (5 ${\mu}$m, 4.6 × 150 mm) and a chromatography data analysis S/W, using a isocratic mobile phase (mixture of 0.01 M ammonium acetate and acetonitrile 80:20 ) at 1.0 ml/min. Its sensitivity, selectivity, accuracy and precision must be adequate for the bioavailabilty study of nicorandil, and the linearity ($r^2$ ≥ 0.9994) of nicorandil was also proved in the range of 0.05 ug/ml . 3 ug/ml. The pharmacokinetic parameters of nicorandil (5 mg) tablets were measured as the follow. AUC: 0.19 ug/ml·hr, $C_{max}$: 0.14 ug/ml, $t_{max}$: 0.58 hr, Ke: 0.11 hr., $t_{1/2\beta}$: 6.76 hrs. This method is simple and sensitive HPLC method using UV detector for determination of nicorandil in human plasma.