• Journal of information and communication convergence engineering
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• v.7 no.4
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• pp.501-506
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• 2009

In the H.264/ AVC video coding standard, the intra-prediction coding with various block sizes offers a considerably high improvement in coding efficiency compared to previous standards. In order to achieve this, H.264/AVC uses the Rate-distortion optimization (RDO) technique to select the best intraprediction mode for a macroblock, and it brings about the drastic increase of the computation complexity of H.264 encoder. To reduce the computation complexity and stabilize the coding performance on visual quality, this paper proposed a fast intra-prediction mode decision algorithm using non-parametric thresholds and simplified directional masks. The use of nonparametric thresholds makes the intra-coding performance not be dependent on types of video sequences and simplified directional masks reduces the compuation loads needed by the calculation of local edge information. Experiment results show that the proposed algorithm is able to reduce more than 55% of the whole encoding time with a negligible loss in PSNR and bitrates and provides the stable performance regardless types of video sequences.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.119-126
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• 2004

In order to elucidate the modes of double-droplet combustion speed in premixed spray flame, the difference between flame propagation speed and droplet cluster disappearance speed are experimentally investigated using a premixed spray burner system, It was confirmed that flame speed concerned with premixed-mode combustion in the spray flame was approximately 2.0 m/s in average while mean disappearance speed of droplet clusters, which were dominated by diffusion-mode combustion in downstream of the flame, was evaluated as much as 0.45 m/s. It was clarified that both characteristics of premixed-mode and diffusion-mode combustion in spray flames are of much difference in nature, even though both speed, which are supposed to depend on local properties of the spray itself and flow conditions surrounding droplet clusters, are scattered in experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.928-936
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• 2012

The microgrid concept assumes a cluster of loads and microsources operating as a single controllable system that provides a new paradigm for defining the operation of distributed generation. This system can be operated as both grid-connected mode and islanded mode. In other words, the microgrid can be operated to meet their special need; such as economics in steady state and local reliability in islanded mode due to the grid fault. This paper presents the AGC (Automatic Generation Control) method for microgrid with EMS (Energy Management System).

• Proceedings of the KSRS Conference
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• 2000.04a
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• pp.79-84
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• 2000

해양 영역에 대한 SAR(Synthetic Aperture Radar) 자료는 좋은 해상도로 기상조건이나 주야에 상관없이 wind vector를 구할 수 있는 장점이 있다. 해안지역의 scatterometer 자료는 육지의 영향으로 인하여 정확한 자료를 얻을 수 없지만, SAR자료를 이용하면, Scatterometer에 비해 좋은 해상도로 해안지역의 wind vector 추출이 가능하다. 본 연구에서는 SAR 자료로부터 풍속을 추출할 수 있는 CMOD_4와 CMOD_IFR2 알고리즘을 사용하였다. 이 알고리즘들은 정확한 sigma-naught 값과, 풍향, 그리고 local incidence angle을 입력변수로 요구한다. CMOD 알고리즘들은 ERS-1/2와 같이 C-band, VV-polarization을 위해 개발된 알고리즘이므로, C-band, HH-polarization을 가진 RADARSAT 자료에 바로 적용할 수가 없다. 이것을 해결하기 위해 본 연구에서는 두 CMOD 알고리즘을 몇 가지 polarization ratio와 같이 적용하여 보았다. 각 연구지역에 해당하는 자료에는 제주도 주변의 Fine mode 자료, 서해안과 제주도 근해의 Standard mode 자료, 그리고 동해안 지역의 ScanSAR 자료 등이다. 여러 가지 Polarization ratio와 CMOD 알고리즘의 조합, 그리고 2-DFFT로부터 추출된 풍향으로부터 각 연구지역의 풍속은 가까운 기상관측소 및, 부이의 관측값과 비교하였다. 그 결과 Fine mode 자료로부터 추출된 풍속은 실제 관측 값보다 항상 상당히 높게 나타났지만, Standard mode 나 ScanSAR 자료로부터 추출된 풍속은 현지 기상관측소 관측 값과 잘 일치한다.

• Journal of Korean Society of Rural Planning
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• v.20 no.4
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• pp.55-66
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• 2014

This study analyzed the recognition of local residents surrounding farmland conversion area. The details of the survey on the residents included recognition of farmland conversion, the usage and reason of farmland conversion in the surrounding area, impacts of farmland conversion on the local region and agricultural production, and change in farmland prices. According to the analysis, the aging of the local residents progressed, and the ratio of farming population was high in the case study area. There were many warehouse facilities and small scale factories in terms of farmland conversion in the case study area, due to the surrounding area characteristics of industrial complex and relatively cheaper land prices. The farmland conversion affected the local area and residents both positively and negatively, and the surrounding area's land prices rose. The policy implications, based on the findings in this study, indicate the following need to be carried out: the consolidation of action on farmland pollution upon farmland conversion, review of planned collective conversion mode, and return of the land price hike profits to the affected local area and residents. Actually, farmland conversion should be conducted, after a comprehensive and systematic review, because it affects the local area and residents in a complex way.

• Journal of the Korean Geographical Society
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• v.44 no.2
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• pp.176-186
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• 2009

Transportation policy to facilitate the public mode use is of the foremost importance to the local governments of Metropolitan Seoul, regarding the economic and environmental consequences of the increasing use of car. Understanding the travel behaviour is essential to the establishment of proper policy to guide more people to the use of public modes instead of private. The paper reports a result of sequential analysis of individual travel behaviour in Metropolitan Seoul, using a multi-dimensional motif search technique applied to Smart Card data that integrates individuals' different public mode uses. Groups of travel patterns with similar sequential information identified distinctive travel behaviour between Seoul north and south and between metro and bus uses. Travel patterns are more bounded within north Seoul and south Seoul respectively than crossing Han River between north and south. Within north and south, travel patterns visiting northern CBD and southern CBD, respectively, as well as their local neighbour in north and south, often use metro and metro-local bus combination, while travel patterns visiting only the north and south locals without CBDs more use only the local bus line and even only the areal bus line.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.700-702
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• 2004

A local-step optimization method is proposed to supplement the global-step optimization methods which adopt online update mode of internal weights and error energy as stop criterion in learning of multilayer perceptrons (MLPs). This optimization method is applied to the standard online error backpropagation(EBP) and the performance is evaluated for a speaker verification system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1925-1932
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• 2000

Damage detection methods using vibration modes are investigated on ring structures and. modal behavior of the slightly asymmetric rings is examined. Mode shapes changes, MSER(modal strain energy ratio) and MCR(modal curvature ratio) are applied to identify the locations of faults or damages. Parameters are calculated and compared by finite element analysis on rings with designed local damages. Damages are modeled as reduced stiffness in the analysis. The results show MSER and MCR can be proper factors to detect local damages in ring structures.

• Computational Structural Engineering
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• v.7 no.3
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• pp.167-176
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• 1994

A local remeshing algorithm using Delaunay property is developed for the analysis on the phenomenon of quasi-static crack propagation, which is a typical problem of accompanying constantly varying geometry. The algorithm performs both remeshing and refinement. The use of M-integral is demonstrated to simulate crack propagation under mixed mode with the edge spalling problem.

• Smart Structures and Systems
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• v.3 no.4
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• pp.423-437
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• 2007

The empirical mode decomposition (EMD) method is well-known for its ability to decompose a multi-component signal into a set of intrinsic mode functions (IMFs). The method uses a sifting process in which local extrema of a signal are identified and followed by a spline fitting approximation for decomposition. This method provides an effective and robust approach for decomposing nonlinear and non-stationary signals. On the other hand, the IMF components do not automatically guarantee a well-defined physical meaning hence it is necessary to validate the IMF components carefully prior to any further processing and interpretation. In this paper, an attempt to use the EMD method to identify properties of nonlinear elastic multi-degree-of-freedom structures is explored. It is first shown that the IMF components of the displacement and velocity responses of a nonlinear elastic structure are numerically close to the nonlinear normal mode (NNM) responses obtained from two-dimensional invariant manifolds. The IMF components can then be used in the context of the NNM method to estimate the properties of the nonlinear elastic structure. A two-degree-of-freedom shear-beam building model is used as an example to illustrate the proposed technique. Numerical results show that combining the EMD and the NNM method provides a possible means for obtaining nonlinear properties in a structure.