• Title/Summary/Keyword: ill-condition

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On the ill - condition of reverse process from structural dynamic response data (구조계의 동적응답을 이용한 역해석에서의 악조건)

  • 양경택
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1998.04a
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    • pp.390-397
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    • 1998
  • An approach to identifying input forces is proposed using measured structural dynamic responses and its analytical model. The identification of input forces is a reverse process and ill-conditioned problem. Its solution is unstable and generally case dependent. In this paper, the ill-condition is described considering characteristic matrix which is defined by reduced dynamic stiffness matrix. Special attention is focused on the condition number of a characteristic matrix used in the solution algorithm of this reverse process. Simple example is presented in support of the ill-condition of a reverse process.

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IMPROVING THE SOLVABILITY OF ILL-CONDITIONED SYSTEMS OF LINEAR EQUATIONS BY REDUCING THE CONDITION NUMBER OF THEIR MATRICES

  • Farooq, Muhammad;Salhi, Abdellah
    • Journal of the Korean Mathematical Society
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    • v.48 no.5
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    • pp.939-952
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    • 2011
  • This paper is concerned with the solution of ill-conditioned Systems of Linear Equations (SLE's) via the solution of equivalent SLE's which are well-conditioned. A matrix is rst constructed from that of the given ill-conditioned system. Then, an adequate right-hand side is computed to make up the instance of an equivalent system. Formulae and algorithms for computing an instance of this equivalent SLE and solving it will be given and illustrated.

AN EVALUATION OF PRECISION FIT OF IMPLANT-SUPPORTED PROSTHESIS USING THE PERIOTEST ($Periotest^{(R)}$를 이용한 임프란트지지 보철물의 적합도 평가에 관한 연구)

  • Kim, Young-Min;Bae, Jeong-Sik
    • The Journal of Korean Academy of Prosthodontics
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    • v.36 no.4
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    • pp.587-597
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    • 1998
  • In this study, the Periotest value was measured with Periotest to evaluate precision fit of the 2-unit and 3-unit implant-supported prosthesis by modifying the size and location of ill-fitted conditions. The 2-unit prosthesis was fabricated with the right implant fitted incorrectly and the 3-unit prosthesis with the right and center implant fitted incorrectly. To evaluate the effects of the ill-fitted sizes, 4 groups were divided.:The control group being the accurately fabricated sample group fitted properly. Group 1 was constructed with $40{\mu}m$ ill-fitted conditions, group 2 with $70{\mu}m$ and group 3 with $100{\mu}m$ ill-fitted conditions. The Periotest value was measured at each implant site after tightening 10Ncm. The result was follows : 1. The PTV on the ill-fitted area in the 2-unit implant-supported prosthesis increased as the ill-fitted conditions increased. There was a statistically significant difference among groups(p<0.05). In the same ill-fitted sample, the PTV depending on the measured location demonstrated a statistically significant difference (p<0.05) 2. The PTV on the ill-fitted area of the 3-unit implant-supported with an ill-fitted condition in the right implant increased as the ill-fitted conditions increased. There was a significant difference among groups (p<0.05). In the same ill-fitted sample, the PTV depending on the measured location demonstrated a statistically significant difference (p<0.05). 3. In the 3-unit implant-supported prosthesis with ill fitting conditions in the center implant, the PTV on the ill-fitted area demonstrated a statistically significant difference between the control group, group 1 and group 2 (p<0.05). In the same ill-fitted sample, the PTV depending on the measured location demonstrated significant difference between the gap side and the adjacent side with over $70{\mu}m$ ill-fitted conditions (p<0.05). The results suggest that Periotest is a valuable objective method for evaluating the precision fit of an implant superstructure.

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Study on Pretreatment of Giant Miscanthus Using Ionic Liquid and Structural Change of Lignin (이온성 액체에 의한 거대억새 전처리 특성 및 리그닌의 구조적 변화 관찰)

  • Park, Shin Young;Hwang, Hyewon;Jang, SooKyeong;Choi, In Gyu;Choi, JoonWeon
    • Journal of the Korean Wood Science and Technology
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    • v.43 no.3
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    • pp.344-354
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    • 2015
  • To investigate the effects of ionic liquid pretreatment on biomass, giant miscanthus was treated with 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) and 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) at three temperature conditions ($90^{\circ}C$, $110^{\circ}C$, and $130^{\circ}C$). As temperature condition increased, yield of the cellulose-rich product (CP) was reduced from 87.2% to 67.6%, while yield of the ionic liquid lignin (ILL) increased from 2.2% to 9.9%. Compared to the ILL, CP had lower carbon contents and higher oxygen contents. Enzymatic hydrolysis of CPs showed that conversion ratio of CP treated with [Emim][OAc] at $110^{\circ}C$ was 56.7%, the highest digestibility. Thermogravimetric analysis indicated that the maximum degradation rate decreased as temperature condition increased. In addition, maximum degradation temperature of ILL treated with [Emim][OAc] ranged from 274 to $279^{\circ}C$ which was lower than that of ILL treated with [Bmim][OAc]. Analytical date for ${\beta}$-O-4 linkage frequency in the ILL revealed that ${\beta}$-O-4 linkage frequency in the ILL decreased as the temperature rose. Furthermore, the highest S/G ratio of the ILL was determined to ca. 1.2 obtained from [Bmim][OAc] treatment at $110^{\circ}C$.

An alleviant technique for solving III-Conditioned Linear Systems Using Spectral Adaptive Mapping (스펙트럼 적응 사상을 이용한 선형시스템의 불량조건 완화기법)

  • Chun, Jae-Woong;Cho, Ki-Seon;Park, Jong-Bae;Shin, Joong-Rin
    • Proceedings of the KIEE Conference
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    • 2003.07a
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    • pp.110-112
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    • 2003
  • This paper presents an alleviant technique for solving ill-conditioned linear systems using spectral adaptive mapping, which is based on spectral mapping theorem. The conventional approaches to solve the ill-conditioned linear systems are divided into reformulation and alleviant technique. So far, the alleviant technique is evaluated the most effective one. In this paper, an adaptive mapping of spectrum is adopted to alleviate the condition number of ill-conditioned linear systems. A shift constant, which is a dominant factor of the spectral adaptive mapping that are proposed, is assessed by the system spectrum. The proposed spectral adaptive mapping technique is tested to demonstrated the validation on several size Hilbert matrices and small scale power systems, which are provide the promising results.

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A Quantitative Performance Input for an Input Observer ( I ) - Analysis in Transient State - (입력관측기의 정량적 성능지표 (I) -과도상태 해석-)

  • Jung, Jong-Chul;Lee, Boem-Suk;Huh, Kun-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.10
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    • pp.2060-2066
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    • 2002
  • The closed-loop state and input observer is a pole-placement type observer and estimates unknown state and input variables simultaneously. Pole-placement type observers may have poor transient performance with respect to ill-conditioning factors such as unknown initial estimates, round-off error, etc. For the robust transient performance, the effects of these ill-conditioning factors must be minimized in designing observers. In this paper, the transient performance of the closed-loop state and input observer is investigated quantitatively by considering the error bounds due to ill-conditioning factors. The performance indices are selected from these error bounds and are related to the observer robustness with respect to the ill -conditioning factors. The closed-loop state and input observer with small performance indices is considered as a well-conditioned observer from the transient perspective.

The Analysis of Risk Exposure and Ill Health Symptom by Difference Depending on the Special Type of Employment (특수형태근로 종사 여부에 따른 작업위험요인과 건강상 문제의 차이 분석)

  • Shin, Saemi;Byeon, Sang Hoon
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.28 no.3
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    • pp.319-329
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    • 2018
  • Objectives: The object of this paper is to analyze difference of general and occupational characters, risk exposure and ill health symptom depending on the special type of employment. Methods: 50,007 participants from Fourth Korean Working Condition Survey conducted in 2014 was analyzed. Cross-tabulation analysis was conducted for deriving difference in general and occupational characters, mulitvariate logistic regression analysis was conducted after controlling general and occupational characters for deriving difference in risk exposure and ill health symptom depending on the special type of employment. Results: In the special type of employment, female, ages of 50, education levels of high school, monthly income of 2,000-3,000 thousand won, job types of sales person, enterprises of less than 100 workers, working duration of 2-10 years and long working hours worker's proportion was higher than general employment. Physical(OR: 0.84, 95% CI: 0.76-0.94) and ergonomic (OR: 0.48, 95% CI: 0.42-0.55) risk exposure was lower, psychological(OR: 1.77, 95% CI: 1.54-2.04) risk exposure was higher than general employment, and there was no significant difference between the special type of employment and general employment in chemical/biological risk exposure(OR: 1.06, 95% CI: 0.94-1.20) and ill health symptom(OR: 0.98, 95% CI: 0.89-1.09). Conclusions: This article offers the analysing difference between the special type of employment and general employment using huge size cross sectional data represent Korean employees.

Real-Time Traffic Sign Detection Using K-means Clustering and Neural Network (K-means Clustering 기법과 신경망을 이용한 실시간 교통 표지판의 위치 인식)

  • Park, Jung-Guk;Kim, Kyung-Joong
    • Proceedings of the Korean Information Science Society Conference
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    • 2011.06a
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    • pp.491-493
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    • 2011
  • Traffic sign detection is the domain of automatic driver assistant systems. There are literatures for traffic sign detection using color information, however, color-based method contains ill-posed condition and to extract the region of interest is difficult. In our work, we propose a method for traffic sign detection using k-means clustering method, back-propagation neural network, and projection histogram features that yields the robustness for ill-posed condition. Using the color information of traffic signs enables k-means algorithm to cluster the region of interest for the detection efficiently. In each step of clustering, a cluster is verified by the neural network so that the cluster exactly represents the location of a traffic sign. Proposed method is practical, and yields robustness for the unexpected region of interest or for multiple detections.

COMPUTATIONAL INTELLIGENCE IN NUCLEAR ENGINEERING

  • UHRIG ROBERT E.;HINES J. WESLEY
    • Nuclear Engineering and Technology
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    • v.37 no.2
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    • pp.127-138
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    • 2005
  • Approaches to several recent issues in the operation of nuclear power plants using computational intelligence are discussed. These issues include 1) noise analysis techniques, 2) on-line monitoring and sensor validation, 3) regularization of ill-posed surveillance and diagnostic measurements, 4) transient identification, 5) artificial intelligence-based core monitoring and diagnostic system, 6) continuous efficiency improvement of nuclear power plants, and 7) autonomous anticipatory control and intelligent-agents. Several changes to the focus of Computational Intelligence in Nuclear Engineering have occurred in the past few years. With earlier activities focusing on the development of condition monitoring and diagnostic techniques for current nuclear power plants, recent activities have focused on the implementation of those methods and the development of methods for next generation plants and space reactors. These advanced techniques are expected to become increasingly important as current generation nuclear power plants have their licenses extended to 60 years and next generation reactors are being designed to operate for extended fuel cycles (up to 25 years), with less operator oversight, and especially for nuclear plants operating in severe environments such as space or ice-bound locations.

Robust Observer Design for Multi-Output Systems Using Eigenstructure Assignment (고유구조 지정을 이용한 다중출력 시스템의 강인한 관측기 설계)

  • Huh, Kun-Soo;Nam, Joon-Chul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.11
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    • pp.1621-1628
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    • 2004
  • This paper proposes a design methodology for the robust observer using the eigenstructure assignment in multi-output systems so that the observer is less sensitive to the ill-conditioning factors such as unknown initial estimation error, modeling error and measurement bias in transient and steady-state observer performance. The robustness of the observer can be achieved by selecting the desired eigenvector matrix to have a small condition number that guarantees the small upper bound of the estimation error. So the left singular vectors of the unitary matrix spanned by space of the achievable eigenvectors are selected as a desired eigenvectors. Also, this paper proposes how to select the desired eigenvector based on the measure of observability and designs the observer with small gain. An example of a spindle drive system is simulated to validate the robustness to the ill-conditioning factors in the observer performance.