• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2001년도 Proceedings of 2001 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.14-22
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• 2001

The frequency responses on the sub-pixel evaluation technique were investigated using the Monte-calro Simulation technique. The frequency response by the FFT based cross-correlation gives very good results, however, the gain loss does exist for the small displacement, (less than 0.5 pixel). While, the no gain loss is observed in the Direct Cross-correlation, however, the sub-pixel accuracy was limited to be about 0.1 pixel, i.e., it could not detect the small displacement. To detect the higher accurate sub-pixel displacement, the gradient based technique is the best. For the small interrogation area (e.g., 4x4), only the gradient technique can detect the small displacement correctly.

• 한국통신학회논문지
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• 제21권8호
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• pp.1885-1896
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• 1996

This paper describes the implementation of the AVT(Automatic video Tracker) using ASIC. The basic tracking algorithm is based on the spatio-temporal gradient method, and adaptive window sizing, track state decision algorithm were also realized. Newly developed ASIC performs recursive image filtering, extraction of spatio-temporal gradient/gradient functions of image in field rate. Using the FPGA/ASIC, the tracker was simply realized in one board type which can be easily applied to various image system. We conformed ASIC operation by computer simulation and tested the system in real tracking situations. From the result, the system can track the moving target which has a velocity of 2-3 pixel/field and a size of varying from 2 to 128 pixes. Also fast refresh rateof motion estimation(60Hz) improves the characteristics of servoing system which forms feedback loop with the tracker.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(4)
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• pp.47-49
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• 2000

In this paper we propose the multiple local search method(MLSM) based on the motion information of the neighbor blocks. In the proposed method motions are estimated from the multiple searches of many candidate local search regions. To reduce the additional search points we avoid to search the same candidate regions previously visited using the distance from the initial search point to the recently found vector points. In the simulation the proposed method shows more excellent results than that of other gradient based method especially in the search of motion boundary.

• 한국통신학회논문지
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• 제21권11호
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• pp.2776-2788
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• 1996

A new feature-based motion parameter estimation for arbitrary-shaped regions is proposed. Existing motion parameter estimation algorithms such as gradient-based algorithm require iterations that are very sensitive to initial values and which often converge to a local minimum. In this paper, the motion parameters of an object are obtained by solving a set of linear equations derived by the motion of salient feature points of the object. In order to estimate the displacement of the feature points, a new process called the "bi-directional correspondence scheme" is proposed to ensure the robjstness of correspondence. The proposed correspondence scheme iteratively selects the feature points and their corresponding points until unique one-to-one correspondence is established. Furthermore, initially obtained motion paramerters are refined using an iterative method to give a better performance. The proposed algorithm can be used for motion estimationin object-based image coder, and the experimental resuls show that the proposed method outperforms existing schemes schemes in estimating motion parameters of objects in image sequences.sequences.

• 한국도로학회논문집
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• 제17권5호
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• pp.123-133
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• 2015

PURPOSES : This study aimed to develop a new highway capacity estimation method and provide comparative results among traditional capacity estimation methods and the recommended values in the latest version of KHCM. METHODS : The limitations of the existing methods, such as inconsistency and underestimation of the capacity value, are summarized through an extensive literature review. To overcome these limitations, a new method is introduced by adopting a definition of capacity and traffic flow characteristics at or near breakdown points. This method can produce the capacity value by searching a point corresponding to the maximum traffic flow through analysis of gradient changes (point of inflection) of the traffic flow and speed distribution. Comparative results of capacity values from each method are also presented to validate the new method by using data collected from detectors on freeways. RESULTS: From the analysis results, it is shown that a consistent capacity value can be estimated by applying the new method. In addition, the resulting capacity values are 3%-4% higher than those recommended in KHCM. CONCLUSIONS : The capacity values listed in the current KHCM tend to produce underestimated results. The new method presented in this paper may be included in the future edition of KHCM.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.2172-2177
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• 2015

상수 모듈러스 오차의 확률을 영으로 줄이는 등화 알고리듬에 결정 궤환 방식이 도입된 DF-MZEP-CME (decision feedback - maximum zero-error probability for constant modulus errors) 알고리듬은 채널 왜곡 보상에서 보다 향상된 성능을 보인다. 그러나 이 DF-MZEP-CME 알고리듬은 기울기 계산에서 샘플 사이즈에 비례하는 계산량을 가지게 되어 구현상 장애요인으로 작용한다. 이 논문에서는 DF-MZEP-CME 알고리듬의 기울기를 반복적으로 추정하도록 하여 계산량이 샘플 사이즈와 무관하게 함으로서 계산량 문제를 해결한다. 샘플 사이즈 N 에 대해 기존 알고리듬이 10N 의 곱셈량을 가지지만 제안한 방식은 샘플 사이즈와 무관하게 단지 20 번의 곱셈을 수행한다. 또한 제안한 방식의 기울기 계산이 초기상태로부터 안정 상태로 넘어갈 때 연속성을 유지하는 것으로 나타나 오차 전파에 예민한 결정 궤환 방식에 매우 적합한 알고리듬으로 판단된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.175-180
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• 2003

An inverse problem to determine two-dimensional total heat exchange factor is studied for the prediction of the billet temperature in the reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. This inverse analysis employs the conjugate gradient method. The total heat exchange factors for 12-zones of the cross-section of the billet are estimated. The estimated temperatures at measurement locations are in good agreements with the measured temperatures.

• 대한기계학회논문집B
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• 제29권11호
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• pp.1257-1264
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• 2005

An inverse problem to determine two-dimensional total heat exchange factor is studied for the prediction of the slab temperature in the reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. This inverse analysis employs the conjugate gradient method. The overall heat absorptances for 12-zones of the cross-section of the slab are estimated. The estimated temperatures at measurement locations are in good agreements with the measured temperatures.

• 전자공학회논문지B
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• 제31B권8호
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• pp.87-98
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• 1994

Object-oriented analysis-synthesis coding subdivides each image of a sequence into moving objects and compensates the motion of each object. Thus it can reconstruct real motion better than conventional motion-compensated coding techniques at very-low-bit-rates. It uses a mapping parameter technique for estimating motion information of each object. Since a mapping parameter technique uses gradient operators it is sensitive to redundant details and noise. To accurately determine mapping parameters, we propose a new analysis method using integral projections for estimation of gradient values. Also to reconstruct correctly the local motion the proposed algorithm divides an image into segmented objects each of which having uniform motion information while the conventional one assumes a large object having the same motion information. Computer simulation results with several test sequences show that the proposed image analysis method in object-oriented analysis-synthesis coding shows better performance than the conventional one.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.494-504
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• 2008

Successful design, construction and maintenance of NATM tunnel demands prediction, control, stability estimation and monitoring of surface settlement, gradient and ground displacement with high accuracy. Back analysis using measured data and forward analysis have been and are indispensable tools to achieve this goal. Sakurai provided the hazard warning levels for assessing the stability of tunnels using the relation of critical strain and apparent Young's modulus. This paper performed the estimation of tunnel stability on construction. Firstly, the apparent Young's modulus concept and back analysis method is introduced for the assessment of tunnel safety during excavation a brief framework. Secondly, this paper deals with case study using "Apparent Young's modulus" and "Back analysis" for the purpose of estimating the stability of NATM tunnel in Korea. Finally, a general method that can be estimated the tunnel stability discussed by a flow chart.