• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.677-680
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• 2004

This study investigates the buckling evaluation of connecting rods used in the diesel engine through finite element analysis. The Rankine formula, which is modified from classical Euler‘s formula, has been widely accepted in automotive industry to evaluate the buckling of connecting rods. Apparently, this formula is most suitable for the straight and idealized rod shape, and over-simplifies the geometric complexity associated with connecting rods. The subspace iteration method in FEA is used to predict the critical buckling stress of a connecting rod with certain slenderness ratio. To create models with various slenderness ratios for shank portion in the rod, the automatic meshing preprocessor was implemented. Results from FEA were verified by the experiments, in which the embedded strain gages measured for the connecting rod running at 4000rpm. The result indicates that the buckling prediction curve through FEA and experiment is effectively different from the curve of classical Rankine formula.

• Journal of International Society for Simulation Surgery
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• 제2권2호
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• pp.64-66
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• 2015

Purpose : In this paper we proposed cascade feature filter and projection method for rapid human face recognition for the large-scale high-dimensional face database. Materials and Methods : The relevant features are selected from the large feature set using Fast Correlation-Based Filter method. After feature selection, project them into discriminant using Principal Component Analysis or Linear Discriminant Analysis. Their cascade method reduces the time-complexity without significant degradation of the performance. Results : In our experiments, the ORL database and the extended Yale face database b were used for evaluation. On the ORL database, the processing time was approximately 30-times faster than typical approach with recognition rate 94.22% and on the extended Yale face database b, the processing time was approximately 300-times faster than typical approach with recognition rate 98.74 %. Conclusion : The recognition rate and time-complexity of the proposed method is suitable for real-time face recognition system on the large-scale high-dimensional face database.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.75-78
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• 1997

In this paper we present new sound spectral analysis methods or prosthetic heart valve sounds. Phonocardiograms(PCG) of prosthetic heart valve were analyzed in order to derive frequency domain feature suitable or the classification of the valve state. The fast orthogonal search method and MUSIC (MUltiple SIgnal Classification) method are described or finding the significant frequencies in PCG. The fast orthogonal search method is effective with short data records and cope with noisy, missing and unequally-spaced data. MUSIC method's key to the performance is the division of the information in the autocorrelation matrix or the data matrix into two vector subspaces, one a signal subspace and the other a noise subspace.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.262-267
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• 1998

In Synthetic Aperture Radar(SAR) imaging, the echoed data are collected by moving radar's position with respect to the target area, and this operation actually gives effect of synthesizing aperture size, which in turn gives better cross range resolution of reconstructed target scene. Among several inversion scheme for SAR Imaging, we uses an inversion scheme which uses no approximation in wave propagation analysis, and try to verify whether the collected data with synthesized aperture actually gives the same support as that with physical aperture in the same size. To do this, we make a signal subspace comparison of two imaging models with physical and synthesized arrays, respectively. Theoretical comparison and numerical analysis using Gram-Schmidt procedures had been performed. The results showed that the synthesized array data fully span the physical array data with the same system geometry and strongly support the proposed inversion scheme valuable in high resolution radar imaging.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.1090-1093
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• 1993

In this paper, the design technique of fuzzy controller using pole placement method and the stability analysis of the system are discussed. The consequent parts of the fuzzy model representing the fuzzy control system are descrived by linear stated equations. It cannot be guaranteed that the total fuzzy system is stable even if all subsystems are stable. The range of the consequent parameters of fuzzy feedback controller which is stable for each fuzzy subspace of the input space are derived, using a rather simplified stability criterion. Then, the consequent parameters of fuzzy controller is determined with the sufficient condition that the fuzzy feedback controller maintain robust stability for the model of other subspace.

• Smart Structures and Systems
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• 제7권2호
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• pp.133-152
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• 2011

System identification is a fundamental step towards the application of structural health monitoring and damage detection techniques. On this respect, the development of evolved identification strategies is a priority for obtaining reliable and repeatable baseline modal parameters of an undamaged structure to be adopted as references for future structural health assessments. The paper presents the identification of the modal parameters of the Guangzhou New Television Tower, China, using a data-driven stochastic subspace identification (SSI-data) approach complemented with an appropriate automatic mode selection strategy which proved to be successful in previous literature studies. This well-known approach is based on a clustering technique which is adopted to discriminate structural modes from spurious noise ones. The method is applied to the acceleration measurements made available within the task I of the ANCRiSST benchmark problem, which cover 24 hours of continuous monitoring of the structural response under ambient excitation. These records are then subdivided into a convenient number of data sets and the variability of modal parameter estimates with ambient temperature and mean wind velocity are pointed out. Both 10 minutes and 1 hour long records are considered for this purpose. A comparison with finite element model predictions is finally carried out, using the structural matrices provided within the benchmark, in order to check that all the structural modes contained in the considered frequency interval are effectively identified via SSI-data.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권7호
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• pp.3268-3283
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• 2018

With the advent of the Information Age, the source identification of digital images, as a part of digital image forensics, has attracted increasing attention. Therefore, an effective technique to identify the source of digital images is urgently needed at this stage. In this paper, first, we study and implement some previous work on image source identification based on sensor pattern noise, such as the Lukas method, principal component analysis method and the random subspace method. Second, to extract a purer sensor pattern noise, we propose a sample selection method to improve the random subspace method. By analyzing the image texture feature, we select a patch with less complexity to extract more reliable sensor pattern noise, which improves the accuracy of identification. Finally, experiment results reveal that the proposed sample selection method can extract a purer sensor pattern noise, which further improves the accuracy of image source identification. At the same time, this approach is less complicated than the deep learning models and is close to the most advanced performance.

• Structural Monitoring and Maintenance
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• 제4권4호
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• pp.331-350
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• 2017

Based on the alternative stabilization diagram by varying the time lag parameter in the stochastic subspace identification analysis, this study aims to investigate the measurements from several cases of civil structures for extending the applicability of a recently noticed criterion to ensure stable identification results. Such a criterion demands the time lag parameter to be no less than a critical threshold determined by the ratio of the sampling rate to the fundamental system frequency and is firstly validated for its applications with single measurements from stay cables, bridge decks, and buildings. As for multiple measurements, it is found that the predicted threshold works well for the cases of stay cables and buildings, but makes an evident overestimation for the case of bridge decks. This discrepancy is further explained by the fact that the deck vibrations are induced by multiple excitations independently coming from the passing traffic. The cable vibration signals covering the sensor locations close to both the deck and pylon ends of a cable-stayed bridge provide convincing evidences to testify this important discovery.

• 한국지능시스템학회논문지
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• 제21권5호
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• pp.569-574
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• 2011

이 논문에서는 마이크로어레이 데이터에 대한 분석 문제로서 부공간 대조집단 식별 문제를 소개하고, 이를 해결하는 방법을 제안한다. 제안한 방법은 부공간에서 속성값이 대조적인 집단의 쌍들을 식별하기 위해, 먼저 각 속성에 대해서 분석자가 지정한 대조영역의 값을 갖는 두 개의 샘플집단을 선택한 다음, 연관규칙 마이닝과 유사한 형태의 방법으로 부공간의 차원을 점진적으로 확대해 가면서 대조집단을 추출한다. 마이크로어레이 데이터는 수천개 이상의 유전자에 대한 발현정보를 포함할 수 있는 다차원 데이터이기 때문에, 대조적인 발현특성을 갖는 유전자집합에 대한 샘플집단의 쌍을 모두 부차원에 대해서 질의를 통해 식별하는 것은 부담이 되지만, 제안한 방법을 사용하면 분석자가 지정한 대조영역 값의 범위를 기준으로 하여 모든 가능한 부공간에서의 대조집단을 효과적으로 추출할 수 있다.

• 한국통신학회논문지
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• 제30권6C호
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• pp.551-559
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• 2005

센서 배열을 이용하여 모르는 신호 매개변수들을 추정하는 것에 대한 연구가 광범위하게 진행되어 왔다. 또한 최근에는 셀룰러 시스템의 이동통신 이용자 수가 폭발적으로 증가되어, 다중 사용자로 인한 간섭이 매우 커지고 있다. 이러한 문제를 해결하기 위한 방법으로 채널 용량을 더 증가시키기 위한 안테나 배열기술의 응용이 연구되고 있다. 이 논문에서는 이동국 근처의 국소적 산란 신호의 새로운 모형을 평균 조정 벡터를 이용하여 만들고, 몇 가지 분포에 대한 수학적 유도를 하였다. 이 모델에서 신호 도래각의 추정은 weighted subspace fitting(WSF) 기법에 바탕을 두었고, 통계적 분석과 모의실험을 통해 성능을 보였다.