• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.429-432
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• 2000

We propose a new frame rate up-conversion algorithm for high quality video. In the proposed scheme bidirectional motion estimation (ME) is performed to construct the motion vector. (MV) field for the frame to be interpolated. Unlike conventional motion-compensated interpolation (MCI) algorithms, the proposed technique does not produce any overlapped pixel and hole region in the interpolated frame, and thus can utilize the overlapped block motion compensation technique to reduce the blocking artifacts. The proposed algoritm is very simple to implement on consumer products when compared to conventional MCI methods. Computer simulation shows a high visual performance of the proposed frame rate up-conversion algorithm.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.64-72
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• 2016

The coverage area of a GNSS regional ionospheric delay model is mainly determined by the distribution of GNSS ground monitoring stations. Extrapolation of the ionospheric model data can extend the coverage area. An extrapolation algorithm, which combines observed ionospheric delay with the environmental parameters, is proposed. Neural network and least square regression algorithms are developed to utilize the combined input data. The bi-harmonic spline method is also tested for comparison. The IGS ionosphere map data is used to simulate the delays and to compute the extrapolation error statistics. The neural network method outperforms the other methods and demonstrates a high extrapolation accuracy. In order to determine the directional characteristics, the estimation error is classified into four direction components. The South extrapolation area yields the largest estimation error followed by North area, which yields the second-largest error.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1911-1914
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• 2003

This paper proposes efficient system for multiview images using backward quadtree disparity estimation. Previous quadtree method usually divides current image. In this work, backward quadtree divides reference image. So, it does not need to code quadtree data. For backward quadtree, quadtree information map is generated. By using this map, adaptive dividing is possible. And, conventional bi-directional matching method is used with backward quadtree. These methods increase subject and object quality of decoded test images. For multiview images, panorama synthesizing method was used. Panorama image and right-most image are used for reference image for intermediate view images coding.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.268-271
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• 2015

본 논문에서는 고해상도 비디오를 위한 프레임 레이트 변환 방법을 제시한다. 서로 다른 방식이나 포맷을 가진 영상 신호를 변환할 때에는 시각적으로 거슬리는 움직임 지터(motion jitter)나 영상의 모서리에서의 블러링(blurring) 현상이 일어날 수 있다. 제시하는 방법에서는 이러한 문제점을 해결하기 위해 양방향 움직임 추정/보상을 이용하여 프레임 레이트를 증가 변환한다. 또한 보다 정확한 움직임 벡터를 찾기 위해 다중 프레임을 통한 양방향 탐색 방법을 제안한다. 먼저, 픽셀 값을 알고 있는 현재 프레임과 이전 프레임간의 움직임 벡터를 이용하여 양방향 움직임 벡터를 얻는다. 얻은 움직임 벡터는 벡터 스무딩 블록을 거친다. 그 후 OBMC(Overlapped Block Motion Compensation)를 이용하여 보간 프레임을 구성한다. 실험 결과는 기존 방법들보다 제안 방법이 주관적 화질 면에서 우수함을 나타낸다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.6
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• pp.333-351
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• 2008

Transmission control protocols have to overcome common problems in wireless networks. TCP employing both packet loss discrimination mechanism and available bandwidth estimation algorithm, known as the good existing solution, shows significant performance enhancement in wireless networks. For instance, TCP New Jersey which exhibits high throughput in wireless networks intends to improve TCP performance by using available bandwidth estimation and congestion warning. Even though it achieves 17% and 85% improvements in terms of goodput over TCP Westwood and TCP Reno, respectively, we further improve it by exploring maximized available bandwidth estimation, handling bit-error-rate error recovery, and effective adjustment of sending rate for retransmission timeout. Hence, we propose TCP NJ+, showing that for up to 5% packet loss rate, it outperforms other TCP variants by 19% to 104% in terms of goodput when the network is in bi-directional background traffic.

• Journal of the Korean Geosynthetics Society
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• v.18 no.1
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• pp.39-53
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• 2019

Bi-directional pile load test (briefly called 'BDH PLT') cannot be performed at loading levels where ultimate bearing capacity could be assessed in field, it is not possible to precisely determine both ultimate load and yield load and under loading. Since the load is transmitted separately to the skin and the end unlike the static pile load test (briefly called 'SPLT') and the direction of loading on the skin is opposite, such methods could have a result different from actual movements of shafts. In this study, three-dimensional finite element method (briefly called '3D FEM') analysis was conducted from results of the BDH PLT, made with barret piles, which were large-diameter cast-in-place concrete piles, and the calculated design constants were applied to the 3D FEM analysis of the SPLT to interpret them numerically and then, actual behaviors of cast-in-place concrete piles were estimated. First, using the results of the BDH PLT with cast-in-place concrete piles, behaviors of the piles made by loading upwards and downwards were analyzed to calculate load-displacement. Second, the design constants, calculated by the 3D FEM analysis and the back analysis, were applied on the 3D FEM analysis for the SPLT, and from these results, behaviors of the SPLT through the BDH PLT was analyzed. Last, the results of the 3D FEM analysis of the SPLT through the BDH PLT was expressed in relationships as {A ratio of bearing capacity of the SPLT and of the BDH PLT (y)} ~ {A ratio of reference displacement and pile circumference (x)}, and they were all classified by reference displacement at 10.0 mm, 15.0 mm, and 25.4 mm.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.8
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• pp.961-967
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• 2014

In onshore and offshore plant engineering, a broad use of pipe system have been achieved and accordingly related technologies has been developed especially in the field of flow control valves. The aim of this study is to suggest the quadruple offset butterfly valve for bi-directional applications which show equivalent operating torque characteristics of the triple offset butterfly valve. Seat design parameters for the quadruple offset butterfly valve are determined by the proposed method utilizing both ANOVA (analysis of variance) and the orthogonal array. Through additive model considering the effect of design parameters on seating torque, mean estimation is performed and thus its optimization results are verified by design of experiment results. The insight obtained from the present study is beneficial for valve design engineers to develop reliable and integrated design of the quadruple offset butterfly valve.

• 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 Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.133-135
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• 2013

The most difficult process in the construction of free-form buildings is to manufacture and construct exterior panels designed in a complex way. The façade of the free-form buildings include flat-panels, one-way curvature-panels, and bi-directional curvature panels. To construct these forms, it is necessary to go through the process of optimizing. But as for the optimizing technologies, BIM-specializing companies exclusively protect those technologies, so small construction companies have difficulty in rough estimates. Therefore, this study was aimed to provide the basic data in making the rough estimates of free-form buildings by carrying out the optimizing process for the façade of Dongdaemun Design Plaza and conducting the rough estimates according to the stage of production methods and optimization.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.310-319
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• 2016

This paper proposes an effective FRUC (Frame Rate Up-Conversion) technique, which is based on ROI (Region Of Interest) separations and adaptive motion vector refinement. In this paper, in order to overcome the weakness of the EBME (Extended Bi-lateral Motion Estimation) algorithm, which is widely known in FRUC techniques, first, the proposed algorithm performs a bi-directional motion estimation for the complementary asymmetric region. Then, the proposed algorithm classifies each block into ROI or non-ROI block and refine motion vectors in accordance with their block characteristics to have a higher accuracy than the conventional EBME algorithm, specially, for the occlusion regions. The experimental results show that the proposed algorithm can improves 0.59dB on average PSNR as compared to the conventional method.