• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.568-570
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• 2003

비월주사(interlaced)에서 순차주사(progressive)로의 변환을 디인터레이싱(de-interlacing)이라 한다. 제안하는 방식은 움직임 검출을 통해 움직임이 없는 영역에서는 앞선 필드정보를 이용하여 별도의 계산량 없이 디인터레이싱을 하게 되며, 움직임이 있는 영역에서는 공간정보(spatial information)를 이용하여 디인터레이싱하는 ELA(Edge based line average) 방식과 양방향 움직임 추정(bi-directional motion estimation)을 통한 시간정보(temporal information)를 이용하여 디인터레이싱하는 움직임 보상방법 간의 가중합산(weighted summation)을 이용하여 디인터레이싱을 수행하는 방법을 제안한다. 이 때 가중치(weight)는 공간 및 시간 정보 모두를 사용하여 결정되어지며, 이렇게 결정되어진 가중치를 통해 각 방식의 단점을 극복하게 된다. 이러한 가중합산을 이용한 방법은 높은 계산복잡도 없이 단순한 구현을 통해 다양한 조건에서 높은 성능의 디인터레이싱이 가능토록 해주며, 그 하드웨어 구현을 용이하게 해준다.

• Proceedings of the Korea Contents Association Conference
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• 2018.05a
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• pp.53-54
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• 2018

This paper introduces an approach to detect motion areas of stationary objects when the camera slightly moves in the scene by computing optical flow. The flow field is computed by two pyramidal architectures of 5 levels which are built by down-sampling the size of the images by half at each level. Two pyramids of images are built and then optical flow is computed at each level. A warping process combines the information and generates a final flow field after applying edge smoothness and outliers reduction steps. Moreover, we convert the flow vectors in order of magnitude and angle to a color map using a pseudo-color palette. Experimental results in the Middlebury optical flow dataset demonstrate the effectiveness of our method compared to other approaches.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.43-51
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• 2004

A method for form error prediction in side wall machining with a flat end mill is suggested. Form error is predicted directly from the tool deflection without surface generation by cutting edge locus with time simulation. Developed model can predict the surface form error about three hundred times faster than the previous method. Cutting forces and tool deflection are calculated considering tool geometry, tool setting error and machine tool stiffness. The characteristics and the difference of generated surface shape in up milling and down milling are discussed. The usefulness of the presented method is verified from a set of experiments under various cutting conditions generally used in die and mold manufacturing. This study contributes to real time surface shape estimation and cutting process planning for the improvement of form accuracy.

• Journal of Biomedical Engineering Research
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• v.14 no.2
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• pp.177-183
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• 1993

Medical imagies with high resolution are coded to be archived and communicated in MPACS. In this paper, we have studied on coding of Cardio-Angiography. Our coding technique is Subband-Vector Quantization. This techniques is irreversible coding method. This technique's advantages are removing blocking artifact and edge degradation, adapting for drastic image change because of dye injection, and fast decoding. We achieved good results for Cardio-Angiography data, but the study on more sophiscated motion estimation techniques and VQ techniques must be performed.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.45-50
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• 2021

The adjustment of lens magnification can make the degree of precision in pattern measurement be improved, but several problems such as high cost, smaller field of view and stage error accumulation are followed. In this paper, a method for precisely measuring patterns is proposed based on gradient transition vector, in order to solve these problems. The performance of our method is evaluated using pattern images with several directions. Also, it is compared with previous methods based on edge and gray-level moment. It is judged that the proposed method outperforms consistent pattern width results, and so could be applied to automation processes for measurement and inspection of precise and complexed patterns in IT, BT industry products.

• Steel and Composite Structures
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• v.42 no.3
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• pp.353-361
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• 2022

In this study, an estimation regarding nonlocal shell model based on wave propagation approach has been considered for vibrational behavior of the double walled carbon nanotubes with distinct nonlocal parameters. Vibrations of double walled carbon nanotubes for chiral indices (8, 3) have been analyzed. The significance of small scale is being perceived by developing nonlocal Love shell model. The influence of changing mechanical parameter Poisson's ratio has been investigated in detail. The dominance of boundary conditions via nonlocal parameter is shown graphically. It is found that on increasing the Poisson's ratio, the frequencies increases. It is noted that the frequencies of clamped-clamped frequencies are higher than that of simply-supported and clamped-free edge conditions. The outcomes of frequencies are tested with earlier computations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.195-199
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• 2021

본 논문에서는 재귀 신경망을 통해 동적 비전 센서 (DVS: Dynamic Vision Sensor)의 출력에서 엣지를 추정하는 방법을 제안한다. 동적 비전 센서는 기존의 일반적인 카메라들과 달리 급격한 움직임이나 밝기 변화에 강인하게 동작한다. 그러나 동적 비전 센서에서 획득한 출력은 각각이 독립적이기 때문에 화소들의 상관관계를 이용한 알고리즘을 사용함에 어려움이 따른다. 제안하는 방법은 센서에서 획득한 출력을 일정한 시간단위로 분할하고 2차원 평면에 투영함으로써 출력의 정보량 및 상관관계를 향상시키고, 이를 재귀 신경망에 통과시켜 엣지 정보를 추정한다. 이 방법은 센서의 출력에 의해 형성된 패턴을 학습하여 엣지를 잘 추출하였으며, 기존의 컴퓨터 비전 알고리즘의 적용 및 시각 관성 측위 등의 분야에서 활용될 수 있다.

• Journal of Broadcast Engineering
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• v.19 no.3
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• pp.362-371
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• 2014

Blur variation caused by camera de-focusing provides a proper cue for depth estimation. Depth from Defocus (DFD) technique calculates the blur amount present in an image considering that blur amount is directly related to scene depth. Conventional DFD methods use two defocused images that might yield the low quality of an estimated depth map as well as a reconstructed infocused image. To solve this, a new DFD methodology based on infocused and defocused images is proposed in this paper. In the proposed method, the outcome of Subbaro's DFD is combined with a novel edge blur estimation method so that improved blur estimation can be achieved. In addition, a saliency map mitigates the ill-posed problem of blur estimation in the region with low intensity variation. For validating the feasibility of the proposed method, twenty image sets of infocused and defocused images with 2K FHD resolution were acquired from a camera with a focus control in the experiments. 3D stereoscopic image generated by an estimated depth map and an input infocused image could deliver the satisfactory 3D perception in terms of spatial depth perception of scene objects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.851-857
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• 2015

In this paper, we estimate the time-dependent C(t) integrals under elastic-plastic-creep conditions. Finite-element (FE) transient creep analyses have been performed for single-edge-notched-bend (SEB) specimens. We investigate the effect of the initial plasticity on the transient creep by systematically varying the magnitude of the initial step load. We consider both the same stress exponent and different stress exponents in the power-law creep and plasticity to elastic-plastic-creep behavior. To estimate the C(t) integrals, we compare the FE analysis results with those obtained using formulas. In this paper, we propose a modified equation to predict the C(t) integrals for the case of creep exponents that are different from the plastic exponent.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.6
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• pp.649-655
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• 2015

In this paper, we propose a defogging algorithm for a single image. Dark channel prior (DCP), which is a well-known defogging algorithm, can cause halo artifacts on boundary regions, low-contrast defogging images, and requires a large computational time. To solve these problems, we use histogram information with DCP on transmission estimation regions and a multi-resolution method. Local histogram information can reduce the low-contrast problem on a defogging image, and the multi-resolution method with edge information can reduce the total computational time and halo artifacts. We validate the proposed method by performing experiments on fog images, and we confirm that the proposed algorithm is more efficient and superior than conventional algorithms.