• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.53-62
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• 2004

In this study, an improved post-processing technique for correcting MRI artifact due to the unknown respiratory motion in the imaging plane is presented. Respiratory motion is modeled by a two-Dimensional linear expending-shrinking movement. Assuming that the body tissues are incompressible fluid like materials, the proton density per unit volume of the imaging object is kept constant. According to the introduced model, respiratory motion imposes phase error, non-uniform sampling and amplitude modulation distortions on the acquired MRI data. When the motion parameters are known or can be estimatead a reconstruction algorithm based on biliner superposition method was used to correct the MRI artifact. In the case of motion parameters are unknown, first, the spectrum shift method is applied to find the respiratory fluctuation function, x directional expansion coefficient and x directional expansion center. Next, y directional expansion coefficient and y directional expansion center are estimated by using the minimum energy method. Finally, the validity of this proposed method is shown to be effective by using the simulated motion images.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.6
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• pp.599-607
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• 2001

In Conventional BMA, the motion vector can describe only translational movement and blocking noise is generated. To overcome this defect, motion estimation using triangular mesh has been proposed. The regular mesh is the method of dividing the image area into equal size triangle and haying the same node connection. It has no additional information about mesh structure, but do not reflect the real motion because it represents the regions by equal mesh structure regardless of the amount of motion. In this paper, motion estimation using dynamic regular mesh is proposed, In this method, the mesh structure is varied from the amount of motion and maintain the form of regular mesh. By the simulation, proposed method have better performance in PSNR and is superior to the other method in convergence rate.

• Tunnel and Underground Space
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• v.29 no.2
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• pp.89-107
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• 2019

Rock joints have an extremely important role in analyzing the mechanical stability and hydraulic characteristics of rock mass structures. Most rock joint parameters are generally indicated as a distribution by statistical techniques. In this research, calculation technique of Joint Center Volume (JCV) is analyzed, which is required for estimating the size distribution having the largest uncertainty among the joint parameters, then a new technique is proposed which is applicable regardless of the shape of survey window. The existing theoretical JCV calculation technique can be applied only to the plane window, and the complete enumeration techniques show the limitations in joint trace type and analysis time. This research aims to overcome the limitations in survey window shape and joint trace type through calculating JCV by using Monte Carlo simulation. The applicability of proposed technique is validated through the estimation results at non-planar survey windows such as curved surface and tunnel surface.

• Journal of Broadcast Engineering
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• v.27 no.4
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• pp.487-498
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• 2022

Depth map is an image that contains distance information in 3D space on a 2D plane and is used in various 3D vision tasks. Many existing depth estimation studies mainly use narrow FoV images, in which a significant portion of the entire scene is lost. In this paper, we propose a technique for generating 360° omnidirectional RGBD images from a sparse set of narrow FoV images. The proposed generative adversarial network based image generation model estimates the relative FoV for the entire panoramic image from a small number of non-overlapping images and produces a 360° RGB and depth image simultaneously. In addition, it shows improved performance by configuring a network reflecting the spherical characteristics of the 360° image.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.84-88
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• 2023

This study proposes an automated tilt measurement method using point cloud for buildings. The proposed method consists of two main steps: 1) exterior wall plane extraction, and 2) edge estimation and angle calculation. To validate the performance of the proposed method, the algorithm is applied to a target building, of which the estimated tilt values are compared with those obtained from a total station, a commonly used tool for tilt measurement. The result shows that most estimated tilt values are within the maximum and minimum ranges of the total station measurement, suggesting that the proposed algorithm provides sufficient measurement accuracy. Furthermore, the proposed method is shown to be automated and reliable as well as free from human-induced errors compared to the total station.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.12
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• pp.1126-1133
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• 2013

For providing personalized intelligent services to users, 3 dimensional indoor positioning technology to recognize the position of person and equipment becomes important. In this paper, the acoustic signal generated from the proliferated smart phone is received from the 5 microphones equipped in the front panel of 3D positioning system, and the two proposed methods estimate the 3D coordinate of the smart phone, and finally it is verified using the implemented experimental system.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.253-256
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• 2007

본 논문은 로봇이 영상을 통해 획득한 특정물체의 기하학적 정보를 이용하여 이족로봇이 안정적으로 보행할 수 있게 하기 위한 균형제어기법을 제안한다. 영상은 핀 홀 카메라 모델을 통해 획득하였으며, 영상에 포함되는 특정물체의 특징성분에 대한 변위와 로봇의 자세와의 상관관계는 핀 홀 카메라 모델을 이용하여 공간좌표계의 특징정보를 평면좌표계의 영상정보에 매칭시킨 후, 특징들의 변위에 따른 로봇 관절 좌표계의 변위를 추정하는 방법으로 구할 수 있었다. 본 논문에서 제안하는 균형제어기법은 별도의 센서없이 카메라만을 이용하여 이족보행 로봇의 균형제어가 가능하다는 장점을 가지며, 소형이족로붓을 이용한 실험을 통해 그 효율성을 검증하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.853-857
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• 2009

2차원 흐름해석 모형인 SMS(Surface-Water Modeling System)와 RAMS(River Analysis Modeling System)를 이용한 유속장 모의를 통해 Manning 조도계수와 와점성계수에 대한 민감도 분석을 수행하여 흐름특성은 Manning 조도계수에 큰 영향을 받음을 알 수 있었다. 본 연구에서는 Manning 조도계수의 변화를 통하여 실측치에 근사한 유속 분포의 모의결과를 도출하고자 현장실측을 통해 취득한 자료를 이용하여 2차원 수치모형의 모의결과와 비교하였다. 국가하천 형산강 본류 중 안강수위관측소에서 부조수위관측소 사이 약 4.3 km 의 구간을 모의구간으로 선정하였으며, $2006{\sim}2007$년에 걸쳐 취득된 현장실측자료를 바탕으로 매개변수 추정 및 모의결과와 비교하였다. 대상구간에 대한 모의결과의 정확도를 개선하기 위하여 하도의 지형특성 등을 고려하여 모의구간을 다수의 구획으로 구분한 후 수심 및 하도 평면선형을 고려한 Manning 조도계수를 차등적으로 할당하여 모의하였다. 이상의 과정을 통해 모의결과의 정확도 제고가 가능함을 관찰할 수 있었다.

• Journal of KSNVE
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• v.8 no.6
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• pp.1023-1029
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• 1998

When one attempts to construct a hologram. one finds that there are many sources of measurement errors. These errors are even amplified if one predicts the pressures close to the sources. The pressure estimation errors depend on the following parameters: the measurement spacing on the hologram plane. the prediction spacing on the prediction plane. and the distance between the hologram and the prediction plane. This raper analyzes quantitatively the errors when these are distributed irregularly on the hologram plane The sensor mismatch and inaccurate measurement location. position mismatch. are mainly addressed. In these cases. one can assume that the measurement is a sample of many measurement events. The bias and random error are derived theoretically. Then the relationship between the random error amplification ratio and the parameters mentioned above is examined quantitatively in terms of energy.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.600-603
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• 2007

We propose a method to estimate the asymptotic stability region(ASR) of a mismatched uncertain variable structure system with a bounded controller. The uncertain system under consideration may have mismatched parameter uncertainties in the state matrix. Using linear matrix inequalities(LMIs) we estimate the ASR and we show the quadratic stability of the closed-loop control system in the estimated ASR. We also give a simple LMI-based algorithm for estimating the ASR. Finally, we give a numerical example in order to show the effectiveness of our method.