• Smart Structures and Systems
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• 제30권3호
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• pp.273-286
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• 2022

In recent years, vision-based monitoring has received great attention. However, structural identification using vision-based displacement measurements is far less established. Especially, simultaneous identification of structural systems and unknown excitation using vision-based displacement measurements is still a challenging task since the unknown excitations do not appear directly in the observation equations. Moreover, measurement accuracy deteriorates over a wider field of view by vision-based monitoring, so, only a portion of the structure is measured instead of targeting a whole structure when using monocular vision. In this paper, the identification of structural system and excitations using vision-based displacement measurements is investigated. It is based on substructure identification approach to treat of problem of limited field of view of vision-based monitoring. For the identification of a target substructure, substructure interaction forces are treated as unknown inputs. A smoothing extended Kalman filter with unknown inputs without direct feedthrough is proposed for the simultaneous identification of substructure and unknown inputs using vision-based displacement measurements. The smoothing makes the identification robust to measurement noises. The proposed algorithm is first validated by the identification of a three-span continuous beam bridge under an impact load. Then, it is investigated by the more difficult identification of a frame and unknown wind excitation. Both examples validate the good performances of the proposed method.

• Wind and Structures
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• 제9권2호
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• pp.159-178
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• 2006

For the slender and flexible cable supported bridges, identification of all the flutter derivatives for the vertical, lateral and torsional motions is essential for its stability investigation. In all, eighteen flutter derivatives may have to be considered, the identification of which using a three degree-of-freedom elastic suspension system has been a challenging task. In this paper, a system identification technique, known as covariance-driven stochastic subspace identification (COV-SSI) technique, has been utilized to extract the flutter derivatives for a typical bridge deck. This method identifies the stochastic state-space model from the covariances of the output-only (stochastic) data. All the eighteen flutter derivatives have been simultaneously extracted from the output response data obtained from wind tunnel test on a 3-DOF elastically suspended bridge deck section-model. Simplicity in model suspension and measurements of only output responses are additional motivating factors for adopting COV-SSI technique. The identified discrete values of flutter derivatives have been approximated by rational functions.

• Journal of Biosystems Engineering
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• 제33권3호
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• pp.196-203
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• 2008

Hybrid robust image processing algorithm to extract visual features of melon during the cultivation was developed based on a wireless tele-operative interface. Features of a melon such as size and shape including position were crucial to successful task automation and future development of cultivation data base. An algorithm was developed based on the concept of hybrid decision-making which shares a task between the computer and the operator utilizing man-computer interactive interface. A hybrid decision-making system was composed of three modules such as wireless image transmission, task specification and identification, and man-computer interface modules. Computing burden and the instability of the image processing results caused by the variation of illumination and the complexity of the environment caused by the irregular stem and shapes of leaves and shades were overcome using the proposed algorithm. With utilizing operator's teaching via LCD touch screen of the display monitor, the complexity and instability of the melon identification process has been avoided. Hough transform was modified for the image obtained from the locally specified window to extract the geometric shape and position of the melon. It took less than 200 milliseconds processing time.

• 인지과학
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• 제15권2호
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• pp.17-22
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• 2004

순간 노출된 형태의 판단 과제에서 균질 연결성의 효과를 체계적으로 검증하기 위해 두실험이 수행되었다. 상하로 연결되거나 분리되어 배치된 두 괄호의 정체 판단에서 관찰된 부적 반복효과가 분리된 자극판을 예상하는 지각 태세에 기인할 가능성(실험 1)과 반응 편중 및 짧은 노출시간에 기인할 가능성(실험 2)을 검토하였다. 실험 1은, 연결된 자극판만을 사용하여, 도형의 한 부분으로 지시된 표적만을 보고하는 조건과 전체 도형을 보고하는 조건 모두에서 부적 반복효과를 관찰하였다. 실험 2는, 노출시간을 늘여 정확 보고율을 높이는 동시에, 애매한 도형을 이용하여 반응 편중의 정도를 계산하였는데, 반응 편중 효과의 제거 후에도 여전히 부적 반복효과를 관찰하였다. 본 연구의 결과는, 과제의 요구가 없어도 균질 연결된 형태들이 분석적으로 처리될 수 있음을 가리키며, 나아가 균질 연결성이 지각 조직화의 원리라는 가설을 부정하는 것으로 보인다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제7권2호
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• pp.73-87
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• 2007

In this paper, based on the American weapon acquisition management framework in DoD Instruction 5000.2 "Operation of the Defence Acquisition System" and the contents of "DoD Guide for Achieving Reliability, Availability, and Maintainability" published by Defense Acquisition University, the kinds and roles of technical reviews are introduced and the identification of RAM related tasks which are performed at levels of technical reviews during acquisition process are considered. And the task allocations for developers, development managers, and users are proposed. Finally the relationships of acquisition management framework, technical reviews and RAM tasks are tabulated.

• 수완나부미
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• 제14권1호
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• pp.193-228
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• 2022

This study investigates the production and perception of Vietnamese tones by Japanese, Lao, and Taiwanese second language (L2) learners [n=30], comparing their performance in an Imitation task to that of Identification and Read-Aloud tasks. The results show that the Imitation task is generally easier for L2 speakers than the Identification and Read-Aloud tasks, suggesting that imitation is performed without some of the skills required by the other two tasks. It is also found that Lao and Taiwanese speakers outperform Japanese speakers, suggesting that prior experience with one tone language facilitates the acquisition of tone in another language. The result on speakers' tonal range show that L2 leaners have significantly narrower tonal F0 range than control Vietnamese speakers [n=11]. The results of error pattern analysis and tonal transcription also suggest that non-modal voice (glottal stop and creakiness) and contour tones (bidirectional fall-rise) are more difficult for L2 learners than modal voice tones (e.g., unidirectional contours: rising, falling, and level).

• 인지과학
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• 제33권1호
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• pp.1-22
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• 2022

지각부하 이론(Lavie, 1995)에 따르면 지각부하가 높을수록 방해자극의 영향이 감소한다. 지각부하를 다룬 연구들은 문자열에서 표적 문자의 탐지에 걸린 반응시간을 측정하는 Eriksen과 Eriksen(1974)의 측면자극 과제(flanker task)를 주로 사용하였다. 한편, 순간 노출되고 사라진 문자열 중 보고해야 할 표적이 후단서로 지시되는 후단서 강제선택 과제에서는 부적 반복효과(negative repetition effect; NRE)가 관찰된다. 이 효과는 나란히 제시된 두 문자가 서로 다른 경우보다 동일할 때, 표적의 식별률이 더 떨어지는 것을 말한다. 후단서 강제선택 과제는 정보처리의 초기지각 단계와 관련한 처리 과정을 잘 보여준다. 본 연구는 지각부하가 후단서 강제선택 과제에서 표적의 정확 식별률과 NRE에 어떤 영향을 미치는지를 검토하고자 하였다. 지각부하는 후단서에 의한 강제선택 대상인 두 문자(표적 후보) 사이에 삽입되는 제3의 문자의 유사성(실험 1; 'ㄹ', 'ㅅ', '·')과 개수(실험 2; 0개, 2개-왼쪽 대각선 배치와 오른쪽 대각선 배치, 4개, 실험3; 2개, 4개)로 조작했다. 실험 1에서 NRE의 경향성이 관찰되었으나 지각부하의 효과는 관찰되지 않았다. 실험 2에서는 NRE가 유의하였으며, 지각부하는 유의하였으나, NRE와의 상호작용은 관찰되지 않았다. 실험 3은 부하자극의 위치 변동성을 도입하여 강화된 지각부하의 수준에 따라 NRE가 변화할 것인지를 다시 확인하였는데, 지각부하의 효과가 관찰되지 않았다. 본 연구의 결과는 순간 노출된 표적에 대한 분리주의과정으로 인해 지각부하가 지각 정보처리의 초기 단계에 영향을 미치지 못하였을 가능성이 있음을 시사한다.

• 한국언어정보학회:학술대회논문집
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• 한국언어정보학회 2002년도 Language, Information, and Computation Proceedings of The 16th Pacific Asia Conference
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• pp.28-35
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• 2002

Automatic identification of Chinese personal names in unrestricted texts is a key task in Chinese word segmentation, and can affect other NLP tasks such as word segmentation and information retrieval, if it is not properly addressed. This paper (1) demonstrates the problems of Chinese personal name identification in some If applications, (2) analyzes the structure of Chinese personal names, and (3) further presents the relevant processing strategies. The geographical differences of Chinese personal names between Beijing and Hong Kong are highlighted at the end. It shows that variation in names across different Chinese communities constitutes a critical factor in designing Chinese personal name Identification algorithm.

• 대한음성학회지:말소리
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• 제57호
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• pp.165-174
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• 2006

In this paper we use a training algorithm, MCE (Minimum Classification Error), to improve the performance of a text-independent speaker identification system. The MCE training scheme takes account of possible competing speaker hypotheses and tries to reduce the probability of incorrect hypotheses. Experiments performed on a small set speaker identification task show that the discriminant training method using MCE can reduce identification errors by up to 54% over a baseline system trained using Bayesian adaptation to derive GMM (Gaussian Mixture Models) speaker models from a UBM (Universal Background Model).

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1997년도 추계학술대회 학술발표 논문집
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• pp.115-120
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• 1997

System identification is the task of inferring a mathematical description of a dynamic system from a series of measurements of the system. There are several motives for establishing mathematical descriptions of dynamic systems. Typical applications encompass simulation, prediction, fault diagnostics, and control system design. The paper demonstrates that neural networks can be used effective for the identification of nonlinear dynamical systems. The content of this paper concerns dynamic neural network models, where not all inputs to and outputs from the networks are measurable. Only one model type is treated, the well-known Innovation State Space model(Kalman Predictor). The identification is based only on input/output measurements, so in fact a non-linear Extended Kalman Filter problem is solved. Even for linear models this is a non-linear problem without any assurance of convergence, and in spite of this fact an attempt is made to apply the principles from linear models, an extend them to non-linear models. Computer simulation results reveal that the identification scheme suggested are practically feasible.