• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.177-177
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• 2015

개수로에서 식생은 항력을 발생하여 평균유속을 감소시킬 뿐만 아니라, 식생영역과 비식생영역의 경계에서 유속 차를 발생시켜 일반 개수로 흐름보다 복잡한 흐름구조를 형성한다. 또한, 식생은 개수로 흐름에서 부피를 차지하여 식생영역의 유량을 감소시킨다. 일반적으로 식생이 식재된 개수로 흐름을 수치모의 할 경우 체적비를 고려하지 않을 때가 많다. 하지만 물과 식생의 체적비가 높을 경우, 식생에 의한 부피를 고려하지 않으면 실제 유속을 과다산정 하여 흐름모의가 정확하지 않다. 그러므로 식생이 있는 흐름을 정확히 수치모의하기 위해 식생의 체적비를 고려하여 실제 유속을 산정하는 것은 매우 중요하다. 본 연구에서는 식생된 개수로 흐름의 수치모의에서 체적비 도입의 필요성을 분석하였다. $k-{\varepsilon}$ 난류모형을 이용하여 수치모의를 수행하였고, 지배방정식에 식생항을 추가하여 식생이 식재된 개수로 흐름을 모의하였다. 식생 체적비를 고려하기 위해 지배방정식에 식생 체적비에 관한 항을 추가하였다. 체적비 도입의 필요성을 알아보기 위해 선행연구의 침수식생 실험수로를 대상으로 수치모의하였다. 식생밀도가 낮은 경우 식생 체적비의 고려 유 무가 모의결과에 미치는 영향이 작았으나, 식생밀도가 높은 경우에는 식생 체적비를 고려한 경우가 보다 정확한 모의결과를 도출 할 수 있었다.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.1
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• pp.73-79
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• 2009

The hydraulic conductivity of porous media is the most important property in soil characteristics. The hydraulic conductivity is determined by outdoor and indoor methods. Indoor methods normally use soil columns for flow test. Assumption of the column test is that fluid one-dimensionally flows through the column. However, fluids may flow toward the wall of the column, resulting in "boundary flow". This study investigated the effect of boundary flow on the hydraulic conductivity by using a permeameter excluding boundary flow. The results showed that the hydraulic conductivity excluding boundary flow was much smaller than the hydraulic conductivity employing the conventional determination method. This study also investigated the effects of particle size and surfactant on the hydraulic conductivity. As the particle size increased, the hydraulic conductivity was increased. The hydraulic conductivity was reduced by increasing surfactant concentration. The result showed that the viscosity of fluid significantly affected the determination of hydraulic conductivity.

• The Journal of Engineering Geology
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• v.19 no.2
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• pp.205-215
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• 2009

The conventional numerical models to analyze flow in subsurface porous media under the transient state usually generate numerical oscillation and unstability due to local flux domain for critical cases such as infiltration into initially dry soil during rainfall period. In this case, it is required refined mesh and small time step, but it decrease efficiency of computation. In this study, numerical unstability in discontinuity domain is removed by applying particle tracking algorithm to simulate unsteady subsurface flow with inflow boundary condition. Finally the hybrid LE FEM improving numerical stability is proposed. The hypothetical domains with unsteady uniform and nonuniform flow field were used to demonstrated algorithm verification. In comparison with analytic solution, we obtained reasonable results and conducted simulation of hypothetical 3-D recharge/pumping area. The proposed algorithm can simulate saturated/unsaturated porous media with more practical problems and will greatly contribute to accuracy and stability of numerical computation.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.567-575
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• 2017

In this study, when diagnosis pancreatic cancer by dual time point PET/CT, we propose SUVm 2.52 as the threshold value for performing the dual time point PET/CT exam. The hypothesis of normal distribution was adopted through data conversion of 60 pancreatic diseases. The proposed SUVm2.52 boundary value showed a significance level that could be applied to both 120 and 180 minutes of delay time scan for pancreatic cancer determination (p<0.05). C-value variation shows that delay time 2 hour test is more useful than delay time 3 hour test. When the SUVm 2.52 is set to the boundary value and the double-time point PET/CT exam is performed, the probability of distinguishing cancer from inflammation in the delayed image is 95%. When the delayed test is performed with the proposed boundary value SUVm 2.52, Compared with general PET / CT scans, it is thought that it may be helpful to distinguish pancreatic cancer.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.6
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• pp.778-786
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• 2002

Scene boundary detection is important in the understanding of semantic structure from video data. However, it is more difficult than shot change detection because scene boundary detection needs to understand semantics in video data well. In this paper, we propose a new approach to scene segmentation using contextual information in video data. The contextual information is divided into two categories: local and global contextual information. The local contextual information refers to the foreground regions' information, background and shot activity. The global contextual information refers to the video shot's environment or its relationship with other video shots. Coherence, interaction and the tempo of video shots are computed as global contextual information. Using the proposed contextual information, we detect scene boundaries. Our proposed approach consists of three consecutive steps: linking, verification, and adjusting. We experimented the proposed approach using TV dramas and movies. The detection accuracy of correct scene boundaries is over than 80%.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.5
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• pp.28-34
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• 2007

A histogram-based road border line extractor is proposed for an efficient road extraction from the high-resolution satellite imagery. The road border lines are extracted from an edge strength map based on the directional histogram difference between the road and the non-road region. The straight and the curved roads are extracted hierarchically from the edge strength map of the original image and the segmented road cluster images, and the road network is constructed based on the connectivity. Unlike the conventional approaches based on the spectral similarity, the proposed road extraction method is more robust to noise because it extracts roads based on the histogram, and is able to extract both the location and the width of roads. In addition, the proposed method can extract roads with various spectral characteristics by identifying the road clusters automatically. Experimental results on IKONOS multi-spectral satellite imagery with high spatial resolution show that the proposed method can extract the straight and the curved roads as well as the accurate road border lines.

• Journal of the Korean Geophysical Society
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• v.3 no.2
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• pp.77-90
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• 2000

Five electrical resistivity dipole-dipole and two seismic reflection surveys were performed in the southeastern margin of the Yongdong basin to delineate the shallow basin architecture. To investigate the intra-basin structure, twenty four resistivity sounding points and three dipole-dipole lines were selected especially in the vicinity of volcanic masses. The basin-fault boundaries are identified in electrical dipole-dipole resistivity section as high resistivity-contrast of approximately $1,500\;{\Omega}{\cdot}m$, characterized as a band of high standard-deviation. They are also effectively clarified in the seismic reflection data: amplitude and continuity contrasts in the common shot gather, first-arrival profiles, complex attribute plots. The intra-basin resistivity structures are constructed by interpolating vertical electrical sounding data and dipole-dipole profiles. The high-resistivity anomalies most likely originate from the northsouth-trending and northeast-dipping volcanic masses, which are to be further quantitatively investigated with geomagnetic and magnetotelluric surveys.

• Journal of the Korea Convergence Society
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• v.10 no.4
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• pp.153-163
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• 2019

The importance and necessity of convergence research to solve complexity and diversity of research problems is more increasing. For successful convergence research, connectivity beyond the boundary and distance between disciplines is a key factor. To understand the current status and characteristics of connectivity among researchers, we investigated the interdisciplinary relationships among 487 researchers' disciplines in a university by using network anaylsis. The results showed that (1) connectivity between similar disciplines were higher than different disciplines, (2) the density and cohesion level of connectivity within the same campuses were higher, and (3) network centrality was concentrated in engineering and medicine. Based on these results, the necessity of overcoming boundaries and distances as obstacles to convergence research and the necessity of diversification of centrality were proposed. While previous studies mainly analyzed the research outcomes, this study is meaningful because it analyzed researchers' connectivity and collaborative structures in the actual convergence research procedures.

• Korean Journal of Cognitive Science
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• v.23 no.2
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• pp.249-267
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• 2012

Individual differences in working memory predict qualitative differences in language processing. High span comprehenders are better able to integrate probabilistic information such as plausibility and animacy, the use of which requires the computation of real world knowledge in syntactic parsing (e.g.,[1]). However, it is unclear whether similar individual differences exist in the use of informative prosodic cues. This study examines whether working memory modulates the use of prosodic boundary information in attachment ambiguity resolution. Prosodic boundaries were manipulated in globally ambiguous relative clause sentences. The results show that high span listeners are more likely to be sensitive to the distinction between different types of prosodic boundaries than low span listeners. The findings suggest that like high-level constraints, the use of low-level prosodic information is resource demanding.

• Composites Research
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• v.12 no.4
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• pp.25-32
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• 1999

A method of calculating the natural frequency corresponding to the first mode of vibration of beams and tower structures, with irregular cross sections and with arbitrary boundary conditions was developed and reported by Kim, D. H. in 1974. In this paper, the result of application of this method to the special orthotropic plates on elastic foundation with free boundaries is presented. Such plates represent the concrete highway slab and hybrid composite pavement on bridges. Any method may be used to obtain the deflection influence surfaces needed for this vibration analysis. Finite difference method is used for this purpose, in this paper. The influence of the modulus of the foundation and the aspect ratio of the plate on the natural frequency is thoroughly studied. The effect of neglecting the mass of the plates on the natural frequency, as the ratio of the point mass/masses to the plate mass increases, is also studied, in deep.