• 제목/요약/키워드: Model over-fitting

검색결과 151건 처리시간 0.022초

ALL POSSIBLE HIERARCHICAL QUADRATIC REGRESSIONS FOR RESPONSE SURFACES

  • KIM SUNG-SOO;KWON SOON-SUN;PARK SUNG-HYUN
    • Journal of the Korean Statistical Society
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    • 제34권3호
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    • pp.209-218
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    • 2005
  • In response surfaces analysis, we often proceed by supposing that, over a limited region of factor space, a polynomial of only first or second degree might adequately approximate the true function. To find the best subset model, all possible quadratic regressions for response surfaces can be very valuable to get optimum solutions under some reasonable experimentations. However, there is a very hard computational burden to get all possible quadratic regressions. In practice, it is sufficient to consider only hierarchical models. In this paper, we propose an algorithm to get all possible hierarchical quadratic regressions for fitting response surfaces.

Non-linear Responses of Hordeum vulgare Germs to Low Doses of Ionizing Radiation

  • Kim, Jin-Kyu;Alla A. Oudalova;Vladimir G. Dikarev
    • 환경생물
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    • 제21권4호
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    • pp.384-391
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    • 2003
  • The induction of chromosome aberrations in Hordeum vulgare germs after irradiation is studied for the dose range of 10 to 1,000 mGy. The relationship between the frequency of aberrant cells and the absorbed dose is shown to be non -linear and has a dose-independent plateau within the range of 56-467 mGy where the level of cytogenetic damage is statistically significantly distinguished from the spontaneous level. The comparison of the goodness of the experimental data fitting with mathematical models of different complexities, using the most common quantitative criteria, demonstrates the benefit of the piecewise linear model over the linear and polynomial ones in approximating the cytogenetical disturbance frequency. The results of our study support the conclusion about indirect mechanism of chromosome aberrations induced by low doses or dose rates mutagenesis.

림프구의 미소핵을 지표로 영광 원자력발전소 주변 사육 돼지의 방사선 생물학적 평가 (Radiobiological Evaluation in Pig Bred in the Vicinity of Yeonggwang Nuclear Power Station Using Micronuclei in Cytokinesis-blocked Lymphocyte)

  • 김세라;강창모;김성호
    • 한국임상수의학회지
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    • 제21권3호
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    • pp.286-290
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    • 2004
  • Cytogenetic and hematological analysis was performed in peripheral blood of pig in the vicinity of Yeonggwang nuclear power station and control area. The frequency of micronuclei (MN) in peripheral blood lymphocytes from pig was used as a biomarker of radiobiological effects resulting from exposure to environmental radiation. An estimated dose of radiation was calculated by a best fitting linear-quadratic model based on the radiation-induced MN formation from the swine lymphocytes exposed in vitro to radiation over the range from 0 Gy to 4 Gy. MN rates in lymphocytes of pig from Yeonggwang nuclear power station and control area were 10.60/1,000 and 11.10/1,000, respectively. There were no significant differences in MN frequencies and hematological values in pig between Yeonggwang and control area. The study indicates that the MN assay in lymphocyte of pig is a rapid, sensitive and accurate method that can be used to monitor a large population exposed to radiation.

Electrogravimetric and Electrochemical Ac Response of Polypyrrole Films

  • Yang, Haesik;Lee, Hochun;Kwak, Juhyoun
    • 분석과학
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    • 제8권4호
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    • pp.663-668
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    • 1995
  • Ion transport of a polypyrrole/chloride (PPy/Cl) film and a polypyrrole/poly(styenesulfonate) (PPy/PSS) film as a function of applied dc potential was investigated by employing electrogravimetric impedance technique and electrochemical impedance technique. The cation and anion contribution to the whole charge capacitance and the diffusion coefficients of cation and anion in a PPy/PSS film were calculated by fitting the electrogravimetric impedance data with proposed model circuit. The diffusion coefficients of $Na^+$ in a 1 M $NaClO_4$ solution are over 1 order of magnitude larger than those of $ClO{_4}^-$, and $ClO{_4}^-$ contribution to charge compensation decreases as dc potential lowers. The charge compensation of a PPy/Cl film ir a 1 M CsCl solution is carried out largely by $Cl^-$ at 0.2 V vs. Ag/AgCl and by $Cs^+$ as well as $Cl^-$ at -0.4 V.

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림프구 미소핵 측정법을 이용한 원자력발전소 주변 소의 이상산에 대한 방사선 생물학적 평가 (The Radiobiological Evaluation on Abnormal Delivery of Cattle around Nuclear Power Plant using Micronucleus Assay in Lymphocyte)

  • 김세라;김성호
    • 한국임상수의학회지
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    • 제20권3호
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    • pp.364-368
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    • 2003
  • Cytogenetic and hematological analysis was performed in peripheral blood from the cattle associated with abnormal delivery around nuclear power plant area. The frequency of micronuclei (MN) in peripheral blood lymphocytes from cattle was used as a biomarker of radiobiological effects resulting from exposure to environmental radiation. An estimated dose of radiation was calculated by best fitting linear-quadratic model based on the radiation-induced MN data over the range from 0 Gy to 4 Gy from the bovine lymphocytes with in vitro irradiation. MN rates in live malformed calf, dams of malformed calves and other cattle living in the same barn from the regions around nuclear power plant, and cattle in control area were 9/1000, 10.8/1000, 13.3/1000 and 10.0/1000, respectively. There were no significant differences in MN frequencies and hematological values between the cattle associated with abnormal delivery around nuclear power plant area and those of control area. This study indicates that the congenital abnormalities near nuclear power plant seemed to be caused by other aetiology.

세포질 분열 차단 림프구를 이용한 울진원자력발전소 주변 소의 미소핵 발생 평가 (Evaluation of micronucleus frequency in cytokinesis-blockedlymphocytes of cattle in the vicinity of Uljin nuclear power station)

  • 김세라;강창모;김성호
    • 대한수의학회지
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    • 제44권3호
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    • pp.343-348
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    • 2004
  • Cytogenetic and hematological analysis was performed in peripheral blood of cattle in the vicinity of Uljin nuclear power station and control area. The frequency of micronuclei(MN) in peripheral blood lymphocytes from cattle was used as a biomarker of radiobiological effects resulting from exposure to environmental radiation. An estimated dose of radiation was calculated by a best fitting linear-quadratic model based on the radiation-induced MN formation from the bovine lymphocytes exposed in vitro to radiation over the range from 0 Gy to 4 Gy. MN ratio in lymphocytes of cattle from Uljin nuclear power station and control area were 8.90/1,000 and 9.60/1,000, respectively. There were no significant differences in MN frequencies and hematological values in cattle between Uljin and control area.

Kinematics of the Envelope and Two Bipolar Jets in L1157

  • 권우진
    • 천문학회보
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    • 제41권1호
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    • pp.72.3-72.3
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    • 2016
  • A massive envelope and a strong bipolar outflow are the two most distinct structures of youngest protostellar systems. We present observational results from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) toward the youngest (Class 0) protostellar system L1157. At an angular resolution of 5 arcseconds, we mapped its well-developed outflow in CO 2-1 over a span of approximately 5 arcminutes. Additionally, we imaged the central envelope with CO isotopes, CS, CN, and N2H+ with an angular resolution of about 2 arcseconds. We show that the bipolar outflow may be represented with a two jet model and constrain its physical properties such as precession/rotation directions, velocities, inclinations, and position angles via cube data fitting. In addition, we discuss the kinematic features of the envelope detected in CO isotopes and N2H+ and present the radius-dependent dust opacity spectral index.

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Discriminative Training of Sequence Taggers via Local Feature Matching

  • Kim, Minyoung
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • 제14권3호
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    • pp.209-215
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    • 2014
  • Sequence tagging is the task of predicting frame-wise labels for a given input sequence and has important applications to diverse domains. Conventional methods such as maximum likelihood (ML) learning matches global features in empirical and model distributions, rather than local features, which directly translates into frame-wise prediction errors. Recent probabilistic sequence models such as conditional random fields (CRFs) have achieved great success in a variety of situations. In this paper, we introduce a novel discriminative CRF learning algorithm to minimize local feature mismatches. Unlike overall data fitting originating from global feature matching in ML learning, our approach reduces the total error over all frames in a sequence. We also provide an efficient gradient-based learning method via gradient forward-backward recursion, which requires the same computational complexity as ML learning. For several real-world sequence tagging problems, we empirically demonstrate that the proposed learning algorithm achieves significantly more accurate prediction performance than standard estimators.

Structural Dynamic System Reconstruction for Model Parameter Estimation

  • Kim, H. Y.;W. Hwang
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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    • pp.527-527
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    • 2000
  • Wean modal parameter estiimation technique by developing a residual based system reconstruction and using the system matrix coordinate transformation. The modal parameters can be estimated from and residues of the system transfer functions expressed in modal coordinate basis, derived from the state space system matrices. However, for modal parameter estimation of mllltivariable and order structural systems over broad frequency bands, this non-iterative algorithm gives high accuracy in the natural fre and damping ratios. From vibration tests on cross-ply and angle-ply composite laminates, the natural frequencies and damping ratios can be estimated using the coordinates of the structural system reconstructed from the experimental frequency response. These results are compared with those of finite element analysis and single-degree-of-freedom curve-fitting..

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