• Korean Journal of Remote Sensing
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• v.27 no.5
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• pp.535-542
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• 2011

We extracted a surface displacement map of Canisteo Peninsula and the surrounding area in West Antarctica by applying 4-pass DInSAR technique to two ERS-1/2 tandem pairs and analyzed the surface displacement of glaciers and sea ice. In the displacement map, glaciers showed fast motion pushing the adjoining land-fast sea ice which has the displacement in the same direction as the glacier. Cosgrove ice shelf showed large displacement pushing the adjoining land-fast sea ice as well. Some sea ice indicated the displacement that is opposite to the land-fast sea ice. This was because the type of the sea ice is drift ice that is affected by ocean current. Therefore, we could confirmed the boundary between land-fast sea ice and drift ice. It was difficult to distinguish ice shelf from ice sheet because they showed similarities both in brightness of the SAR images and in fringe rates of the interferograms. However, a boundary between fast-moving ice shelf and stable ice sheet was easily confirmed in the displacement map after the phase unwrapping process.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.3
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• pp.177-182
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• 2007

The effects of three fuselage head shapes and nonplanar ground surface on the aerodynamic characteristics of FAST fuselages are investigated using a boundary element method. Wind tunnel test is also performed to validate the present method and to identify the wall effect on the frictional drag which cannot be analyzed using the present method. It is found that the channel has an effect of increasing the lift of those investigated fuselages. The optimal head shape depends on the design conditions of the FAST and its guideway channel. Comparing the calculated induced drag with the measured total drag, it can be concluded that the profile drag is independent of the ground height. Thus, the present numerical method can be applied to the conceptual design of the high-speed ground transporters if only the profile drag of the vehicle in free flight is assumed to be known.

• The KIPS Transactions:PartC
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• v.19C no.2
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• pp.153-166
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• 2012

Multicast service will be required to be an important form of communication without interruption to the delivery of multicast service in mobile networks increasing MNs. In this paper, we review current status of PMIPv6(Proxy Mobile IPv6) multicast listener support being standardized in the IETF and point out limitations of the current approach and we proposed a fast multicast handover procedure in inter domain PMIPv6 network of network-based mobility management. The proposed Fast multicast handover procedure in inter domain optimizes multicast management by using the context of the MNs. We evaluate the proposed fast multicast handover procedure compared to the based one through the developed analytical models and confirm that introduced fast multicast handover procedure provides the reduced service interruption time and total network overhead compared to the based one during handovers.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04c
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• pp.353-355
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• 2003

본 논문은 유전자 알고리즘의 다양성(diversity)을 유지하면서 동시에 수렴(convergence) 속도를 향상시키기 위한 새로운 선택기법을 제안한다. 이를 위해 적합도가 높은 염색체를 다음 세대로 전달하면서 동시에 적합도가 낮은 염색체에 대해서도 일정 수준 전달되게 하였다. 또한 기존의 설러 선택기법 중 가장 일반적으로 사용되는 토너먼트 선택 기법의 문제점을 고찰하고, 제안 알고리즘의 최적도 밀 수렴속도를 모의 실험을 통해 비교 및 분석한다. 실험 결과로부터 제안 알고리즘은 기존의 토너먼트 선택기법에 비해 우수함을 확인하였다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1996.11a
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• pp.145-150
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• 1996

정보보호기법을 적용한 다양한 서비스의 구현에 있어서는 적용기법에서 채택한 암호학적 연산에 의해 그 실용성이 종속하게 되며 이러한 실용화를 위한 하드웨어 또는 소프트웨어적 구현기법에 관한 많은 연구가 진행되고 있다. 본 논문에서는 유한체 GF(2$^{m}$ )상에서의 역원계산을 효율적이며 신속하게 처리할 수 있는 방법에 관해서 다루고 있다. 본 논문에서 제안하는 방법은 정규기저를 이용하여 임의의 유한체위에 적용 가능하도록 설계된 기법이다. 본 논문에서의 제안 방법은 이미 알려진 Itoh의 방법보다 대부분의 정수에 대하여 효율적임을 보인다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2465-2473
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• 2012

Recently, as one of low complexity video encoding methods, DVC (Distributed Video Coding) scheme has been actively studied. Most of DVC schemes exploit feedback channel to achieve better coding performances, however, this causes these schemes to have high decoding delay. In order to overcome these, this paper proposes a new fast DVC decoding method using parity-bit request model, which can be obtained by using bit-error rate, sent by encoder with motion vector, which is transmitted through feedback channel by decoder after generating side information. Through several simulations, it is shown that the proposed method improves greatly the decoding speed, compared to the conventional schemes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.13-20
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• 2010

We proposed a new technique to perform fast video stabilization using integral image in this article. In the proposed technique, it evaluate local and global motion by the block matching using the generated integral image for each frame and compensate the motion like jitter. We made the various experimental jitter patterns to evaluate the effectiveness of the proposed technique and evaluated stabilization capability and execution time with the existing ones. Through the experiment, we found that the execution time of proposed technique was faster than that of existing techniques and the compensation of jitter was well done.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.847-856
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• 2013

This paper presents an AP placement technique considering indoor location-awareness and examines its performance. The proposed AP placement technique is addressed from three performance metrics: location-awareness and AP-based wireless network performance as well as its cost. The proposed AP placement technique consists of meta-heuristic algorithms that yield a near optimal AP configuration for given performance metrics, and deterministic algorithms that improve the fast convergence of the near optimal AP configuration. The performance of the AP placement technique presented in this paper is measured under the environments simulating indoor space, and numerical results obtained by experimental evaluation yield the fast convergence of a near-optimal solution to a given performance metric.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8C
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• pp.764-771
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• 2009

In this paper, we propose a fast multiple reference frame selection method using neighboring motion vectors and the correlation of inter-mode blocks in H.264 video coding. Using the property that an optimal reference frame has the statistical characteristics, the motion estimation of small Inter-block size is estimated from the motion estimation of the larger Inter-block size. Simulation results show that the proposal method decreased the computations about 91%. Without the sacrifice of coding performance, comparing to the H.264 multiple reference picture coding.

• Journal of Broadcast Engineering
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• v.25 no.3
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• pp.338-345
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• 2020

Versatile Video Coding (VVC), which has been developing as a next generation video coding standard, has adopted various techniques to achieve more than twice the compression performance of HEVC (High Efficiency Video Coding). The recently released VVC Test Model (VTM) shows 38% Bjontegaard Delta bitrate (BD-rate) improvement and 9x/1.6x encoding/decoding complexity over HEVC. In order to reduce such increased complexity, various fast algorithms have been proposed. In this paper, gradient-based methods of fast intra mode decision and block splitting are presented. Experimental results show that, compared to VTM6.0, the proposed method gives up to 65% encoding time reduction with 3.54% BD-rate loss in All-Intra (AI) configuration.