• Title/Summary/Keyword: Approach Analysis

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Analysis of DGPS Approach and Landing Accuracy using Air Base Precision Approach Radar (비행기지 PAR을 이용한 DGPS 공항 접근 및 착륙 정확도 분석)

  • Koo, Jung;Pyo, Sang-Ho;Kang, Kyeong-Sung;Kim, Ki-Hyung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.5
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    • pp.788-797
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    • 2011
  • This paper analyzes the accuracy on the approach and landing of aircraft to an airport through comparison with airbase Precision Approach Radar and aircraft track data of DGPS equipped in aircraft. The proposed analysis result could be a basis for verifying the possibility that DGPS can be utilized in Airbase precision approach and landing. Position identification capability of widely used commercial DGPS is fairly accurate on latitude and longitude, while there is a slight error for being used in an airbase accurate approach and landing of Category I precision when it comes to altitude. Thus, we tested accuracy by analyzing actual flight track data of high performance aircraft to verify the accuracy of the airbase approach and landing using DGPS. Through the research, we developed instrumentation to compare PAR track data with DGPS track data, which can be used in reducing the number of PAR verification Flight utilizing it as a system measuring PAR accuracy at PAR installation phase.

Nonlinear damage detection using linear ARMA models with classification algorithms

  • Chen, Liujie;Yu, Ling;Fu, Jiyang;Ng, Ching-Tai
    • Smart Structures and Systems
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    • v.26 no.1
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    • pp.23-33
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    • 2020
  • Majority of the damage in engineering structures is nonlinear. Damage sensitive features (DSFs) extracted by traditional methods from linear time series models cannot effectively handle nonlinearity induced by structural damage. A new DSF is proposed based on vector space cosine similarity (VSCS), which combines K-means cluster analysis and Bayesian discrimination to detect nonlinear structural damage. A reference autoregressive moving average (ARMA) model is built based on measured acceleration data. This study first considers an existing DSF, residual standard deviation (RSD). The DSF is further advanced using the VSCS, and then the advanced VSCS is classified using K-means cluster analysis and Bayes discriminant analysis, respectively. The performance of the proposed approach is then verified using experimental data from a three-story shear building structure, and compared with the results of existing RSD. It is demonstrated that combining the linear ARMA model and the advanced VSCS, with cluster analysis and Bayes discriminant analysis, respectively, is an effective approach for detection of nonlinear damage. This approach improves the reliability and accuracy of the nonlinear damage detection using the linear model and significantly reduces the computational cost. The results indicate that the proposed approach is potential to be a promising damage detection technique.

Welding Deformation Analysis of Plates Using the Inherent Strain-based Equivalent Load Method (고유변형률 기반 등가하중법을 이용한 판의 용접변형 해석)

  • Lee, Joo-Sung
    • Journal of Welding and Joining
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    • v.28 no.2
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    • pp.39-46
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    • 2010
  • IIn this study, used is the equivalent loading method based on the inherent strain to predict the welding deformation of panel members. Equivalent loads are computed from the inherent strain distribution around weld line, and then applied for the linear finite element analysis. Thermal deformation of panel members can be, of course, carried out through the rigorous thermal elasto-plastic analysis procedure but it is not practical in applying to predicting the welding deformation of large structures such as blocks found in a ship structure from view of computing time. The present equivalent load approach has been applied to flat plate model to verify the present approach, and to several curved plate models having the curvature in the welding direction to investigate the effect of the longitudinal curvature upon the weld-induced deformation. The results are compared with those by thermal elasto-plastic analysis. As far as the present results are concerned, it can be said that the present approach shows good agreement with the results by welding experiment and the rigorous thermal elasto-plastic analysis. The present approach has been also applied to predict the welding deformation of panel block as for application illustration to practical model.

Self-adaptive sampling for sequential surrogate modeling of time-consuming finite element analysis

  • Jin, Seung-Seop;Jung, Hyung-Jo
    • Smart Structures and Systems
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    • v.17 no.4
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    • pp.611-629
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    • 2016
  • This study presents a new approach of surrogate modeling for time-consuming finite element analysis. A surrogate model is widely used to reduce the computational cost under an iterative computational analysis. Although a variety of the methods have been widely investigated, there are still difficulties in surrogate modeling from a practical point of view: (1) How to derive optimal design of experiments (i.e., the number of training samples and their locations); and (2) diagnostics of the surrogate model. To overcome these difficulties, we propose a sequential surrogate modeling based on Gaussian process model (GPM) with self-adaptive sampling. The proposed approach not only enables further sampling to make GPM more accurate, but also evaluates the model adequacy within a sequential framework. The applicability of the proposed approach is first demonstrated by using mathematical test functions. Then, it is applied as a substitute of the iterative finite element analysis to Monte Carlo simulation for a response uncertainty analysis under correlated input uncertainties. In all numerical studies, it is successful to build GPM automatically with the minimal user intervention. The proposed approach can be customized for the various response surfaces and help a less experienced user save his/her efforts.

The Relationship between Autonomy and Achievement Motivation of University Players (대학선수들의 자율성과 성취동기와의 관계)

  • Hwang, Sung-Geun
    • Journal of Digital Convergence
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    • v.14 no.3
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    • pp.465-471
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    • 2016
  • This study intends to figure out the relationship between autonomy and achievement motivation of the university players. For this purpose, Survey was performed to Seoul and Metropolitan area's 25 sports 396 Players., And using SPSS 18 and AMOS program descriptive statistics, exploratory factor analysis, confirmatory factor analysis, reliability analysis were conducted. Based on purified data through the process, the relationship between autonomy and achievement motivation was verified with correlation analysis and regression analysis. As a result, autonomy was recognized by male player higher than female player, and in goal-orientation of the access tendency of achievement goal orientation, male player showed higher scores. And in mastery-avoidance of avoidance, female player showed higher scores and in performance-avoidance, male player showed higher scores. According to regression analysis, autonomy affects mastery-approach and achievement goal orientation of the performance-approach.

Multilevel approach for the local nanobuckling analysis of CNT-based composites

  • Silvestre, N.;Faria, B.;Duarte, A.
    • Coupled systems mechanics
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    • v.1 no.3
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    • pp.269-283
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    • 2012
  • In the present paper, a multilevel approach for the local nanobuckling analysis of carbon nanotube (CNT) based composite materials is proposed and described. The approach comprises four levels, all of them at nanoscale. The first level aims to propose the potential that describes the interatomic forces between carbon atoms. In the second level, molecular dynamics simulations are performed to extract the elastic properties of the CNT. The third level aims to determine the stiffness of the material that surrounds the CNT (matrix), using the annular membrane analysis. In the fourth level, finite strip analysis of the CNT elastically restrained by the matrix is performed to calculate the critical strain at which the CNT buckles locally. In order to achieve accurate results and take the CNT-matrix interaction into account, the $3^{rd}$ and $4^{th}$ steps may be repeated iteratively until convergence is achieved. The proposed multilevel approach is applied to several CNTs embedded in a cylindrical representative volume element and illustrated in detail. It shows that (i) the interaction between the CNT and the matrix should be taken into account and (ii) the buckling at nanoscale is sensitive to several types of local buckling modes.

Prediction of post fire load deflection response of RC flexural members using simplistic numerical approach

  • Lakhani, Hitesh;Singh, Tarvinder;Sharma, Akanshu;Reddy, G.R.;Singh, R.K.
    • Structural Engineering and Mechanics
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    • v.50 no.6
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    • pp.755-772
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    • 2014
  • A simplistic approach towards evaluation of complete load deflection response of Reinforced Concrete (RC) flexural members under post fire (residual) scenario is presented in this paper. The cross-section of the RC flexural member is divided into a number of sectors. Thermal analysis is performed to determine the temperature distribution across the section, for given fire duration. Temperature-dependent stress-strain curves for concrete and steel are then utilized to perform a moment-curvature analysis. The moment-curvature relationships are obtained for beams exposed to different fire durations. These are then utilized to obtain the load-deflection plots following pushover analysis. Moreover one of the important issues of modeling the initial stiffness giving due consideration to stiffness degradation due to material degradation and thermal cracking has also been addressed in a rational manner. The approach is straightforward and can be easily programmed in spreadsheets. The presented approach has been validated against the experiments, available in literature, on RC beam subjected to different fire durations viz. 1hr, 1.5hrs and 2hrs. Complete load-deflection curves have been obtained and compared with experimentally reported counterparts. The results also show a good match with the results obtained using more complicated approaches such as those involving Finite element (FE) modeling and conducting a transient thermal stress analysis. Further evaluation of the beams during fire (at elevated temperatures) was performed and a comparison of the mechanical behavior of RC beams under post fire and during fire scenarios is made. Detailed formulations, assumptions and step by step approach are reported in the paper. Due to the simplicity and ease of implementation, this approach can be used for evaluation of global performance of fire affected structures.

Polymorphic Wonn Detection Using A Fast Static Analysis Approach (고속 정적 분석 방법을 이용한 폴리모픽 웹 탐지)

  • Oh, Jin-Tae;Kim, Dae-Won;Kim, Ik-Kyun;Jang, Jong-Soo;Jeon, Yong-Hee
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.19 no.4
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    • pp.29-39
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    • 2009
  • In order to respond against worms which are malicious programs automatically spreading across communication networks, worm detection approach by generating signatures resulting from analyzing worm-related packets is being mostly used. However, to avoid such signature-based detection techniques, usage of exploits employing mutated polymorphic types are becoming more prevalent. In this paper, we propose a novel static analysis approach for detecting the decryption routine of polymorphic exploit code, Our approach detects a code routine for performing the decryption of the encrypted original code which are contained with the polymorphic exploit code within the network flows. The experiment results show that our approach can detect polymorphic exploit codes in which the static analysis resistant techniques are used. It is also revealed that our approach is more efficient than the emulation-based approach in the processing performance.

Identifying Promising Service Areas for Technology-based Firms (기술기반 기업의 유망 서비스 영역 탐색)

  • Kim, Chulhyun
    • Journal of the Korea Safety Management & Science
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    • v.15 no.4
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    • pp.407-416
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    • 2013
  • This paper proposes an approach to analyzing the relationship between technology and services, and to identifying promising service areas for technology-based firms with the analysis of business model (BM) patents. First, BM patents and technology patents are collected and classified into their relevant categories, respectively. Second, patent citation analysis is conducted to analyze the linkage and impacts between each technology and service field at macro level. Third, as a micro level analysis, patent co-classification analysis is employed to identify the interrelationships among specific technology and service areas. Finally, the promising service areas for technology-based firms seeking service areas for diversification is investigated with portfolio analysis. The working of the proposed approach is provided with the help of a case study of IT and mobile services. The proposed approach could guide and help managers of technology-based firms to discover the opportunity of the diversification to new areas in emerging service fields.

An Interval Approach for Design and Analysis of Mechanical Systems with Uncertainties

  • Shin, Jae-Kyun;Li Chen;Jang, Woon-Geun
    • International Journal of Precision Engineering and Manufacturing
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    • v.3 no.4
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    • pp.5-14
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    • 2002
  • This paper addresses the challenges of dealing with uncertainties based on interval analysis. An interval approach is proposed on the basis of Boundary Selection Method (BSM) for treating systems of linear interval equations in the presence of columnwise dependencies. An iterative procedure is developed for the problem solving where uncertainties are characterized in the form of interval quantities. An applied example is used to illustrate effectiveness and usefulness of the proposed approach. This new method can be applied for such circumstances that involve finite element analysis of structures, inverse dynamic analysis of mechanisms, and worst case design studies in the presence of the uncertainties.