• Title/Summary/Keyword: 근사화 기법

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Determination of coagulant input rate in water purification plant using K-means algorithm and GBR algorithm (K-means 알고리즘과 GBR 알고리즘을 이용한 정수장 응집제 투입률 결정 기법)

  • Kim, Jinyoung;Kang, Bokseon;Jung, Hoekyung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.25 no.6
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    • pp.792-798
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    • 2021
  • In this paper, an algorithm for determining the coagulant input rate in the drug-injection tank during the process of the water purification plant was derived through big data analysis and prediction based on artificial intelligence. In addition, analysis of big data technology and AI algorithm application methods and existing academic and technical data were reviewed to analyze and review application cases in similar fields. Through this, the goal was to develop an algorithm for determining the coagulant input rate and to present the optimal input rate through autonomous driving simulator and pilot operation of the coagulant input process. Through this study, the coagulant injection rate, which is an output variable, is determined based on various input variables, and it is developed to simulate the relationship pattern between the input variable and the output variable and apply the learned pattern to the decision-making pattern of water plant operating workers.

Stereo Image-based 3D Modelling Algorithm through Efficient Extraction of Depth Feature (효율적인 깊이 특징 추출을 이용한 스테레오 영상 기반의 3차원 모델링 기법)

  • Ha, Young-Su;Lee, Heng-Suk;Han, Kyu-Phil
    • Journal of KIISE:Computer Systems and Theory
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    • v.32 no.10
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    • pp.520-529
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    • 2005
  • A feature-based 3D modeling algorithm is presented in this paper. Since conventional methods use depth-based techniques, they need much time for the image matching to extract depth information. Even feature-based methods have less computation load than that of depth-based ones, the calculation of modeling error about whole pixels within a triangle is needed in feature-based algorithms. It also increase the computation time. Therefore, the proposed algorithm consists of three phases, which are an initial 3D model generation, model evaluation, and model refinement phases, in order to acquire an efficient 3D model. Intensity gradients and incremental Delaunay triangulation are used in the Initial model generation. In this phase, a morphological edge operator is adopted for a fast edge filtering, and the incremental Delaunay triangulation is modified to decrease the computation time by avoiding the calculation errors of whole pixels and selecting a vertex at the near of the centroid within the previous triangle. After the model generation, sparse vertices are matched, then the faces are evaluated with the size, approximation error, and disparity fluctuation of the face in evaluation stage. Thereafter, the faces which have a large error are selectively refined into smaller faces. Experimental results showed that the proposed algorithm could acquire an adaptive model with less modeling errors for both smooth and abrupt areas and could remarkably reduce the model acquisition time.

Efficient Bitrate Control Scheme for Scalable Video Codec (Scalable Video Codec을 위한 효율적인 비트율 제어기법)

  • Park Nae-Ri;Jeon Dong-San;Kim Jae-Gon;Han Jong-Ki
    • Journal of Broadcast Engineering
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    • v.10 no.4 s.29
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    • pp.488-504
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    • 2005
  • In this paper, we propose a new bitrate control scheme to improve the quality of image encoded by SVC and to resolve the problems of conventional scheme. In JSVM2.0, bitrate of a frame is controlled by an initial quantization parameter and scaling factor that it hasdifferent value according to frame. Itis difficult to get the best of video quality at arbitrary bitrate because the conventional scheme has two defects. One is that we have to know proper initial QP's fur all sequences. Another is that QP's control skill for macroblocks is very inefficient. In this paper, we propose an efficient bit allocation algorithm to reduce the effect of the initial QP and to increase the efficiency of bit allocation by using proper QP's for macroblocks. In simulation results, it can be seen that using the proposed scheme enables the SVC encoder to control the bitrate by the macroblock unit and outperforms the conventional schemes in the respect of rate-distortion.

Estimation of Shaft Resistance of Drilled Shafts Based on Hoek-Brown Criterion (Hoek-Brown 공식을 이용한 현장타설말뚝의 주면마찰력 산정)

  • 사공명;백규호
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.209-220
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    • 2003
  • Modification of general Hoek and Brown criterion is carried out to estimate the shaft resistance of drilled shaft socketed into rock mass. Since the general Hoek-Brown criterion can consider the in-situ state of the rock mass, the proposed method, estimating the unit shaft resistance of drilled shafts based on the Hoek-Brown criterion, has increased flexibility compared to other methods exclusively considering uniaxial compressive strength of intact rocks. The proposed method can form the upper and lower bounds, and most culled data (from 21 pile load tests) from the literature can be found between these two bounds. A comparison between the estimated and observed unit shaft resistances shows quite a good correlation even with crude assumptions for the input parameters. The best-fit line drawn from this analysis shows that at the lower strength of intact rocks (up to 10MPa), Horvath and Kenney's equation shows a good correlation with the measured values, and fur strong rocks Rosenberg and Journeaux's equation provides a close estimation with colleted data. The results of parametric studies for GSI and confining stress show that the normalized unit shaft resistance increases with these two factors. In addition, coefficient of the equational form of the estimation can vary with GSI and confining stresses.

Hydraulic Characteristics of Dam Break Flow by Flow Resistance Stresses and Initial Depths (흐름저항응력 및 초기수심에 따른 댐붕괴류의 수리특성)

  • Song, Chang Geun;Lee, Seung Oh
    • Journal of Korea Water Resources Association
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    • v.47 no.11
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    • pp.1077-1086
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    • 2014
  • The flood wave generated due to dam break is affected by initial depth upstream since it is related with hydraulic characteristics propagating downstream, and flow resistance stress has influence on the celerity, travel distance, and approaching depth of shock wave in implementing numerical simulation. In this study, a shallow water flow model employing SU/PG scheme was developed and verified by analytic solutions; propagation characteristics of dam break according to flow resistance and initial depth were analyzed. When bottom frictional stress was applied, the flow depth was relatively higher while the travel distance of shock wave was shorter. In the case of Coulomb stress, the flow velocity behind the location of dam break became lower compared with other cases, and showed values between no stress and turbulent stress at the reach of shock wave. The value of Froude number obtained by no frictional stress at the discontinuous boundary was the closest to 1.0 regardless of initial depth. The adaption of Coulomb stress gave more appropriate results compared with turbulent stress at low initial depth. However, as the initial depth became increased, the dominance of flow resistance terms was weakened and the opposite result was observed.

Methodological Improvement of the Cumulative Risk Assessment of Health Impact Assessment in Environmental Impact Assessment - Focused on the Industrial Complex Development Projects in the Last Decade - (환경영향평가서 내 건강영향평가의 누적위해성평가 방법론적 개선 - 과거 10년 국내 산업단지 개발 사례를 중심으로 -)

  • Kim, Eunchae;Ha, Jongsik
    • Journal of Environmental Impact Assessment
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    • v.30 no.6
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    • pp.413-424
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    • 2021
  • Health impact assessment in the environmental impact assessment is conducted to determine whether to exceed the standard of each single substance and to establish appropriate reduction measures. In some development projects, although all substances in risk assessment meet the standard, exposure concentration is very close to it. However, considering the cumulative exposure of all substances, health effects are likely to occur considerably severer than those of individual substances, so it is necessary to prepare a concrete and improved methodology for integrating evaluation of emissions to identify the health effects actually exposed to receptors of living things. This study established the definition of cumulative risk assessment through overseas advanced cases and domestic and foreign literature reviews, and proposed a methodology for utilizing cumulative risk assessment considering health effects on multiple substances when developing industrial complexes. Applied by the proposed methodology, integrated indicators forfourtypes of hazardous heavy metals (Ni, Cr6+, Cd, As) emitted from industrial complexes were calculated, and applicability was tested with case of the industrial complex development projects conducted over the last decade (2011-2020).

Gridding of Automatic Mountain Meteorology Observation Station (AMOS) Temperature Data Using Optimal Kriging with Lapse Rate Correction (기온감률 보정과 최적크리깅을 이용한 산악기상관측망 기온자료의 우리나라 500미터 격자화)

  • Youjeong Youn;Seoyeon Kim;Jonggu Kang;Yemin Jeong;Soyeon Choi;Yungyo Im;Youngmin Seo;Myoungsoo Won;Junghwa Chun;Kyungmin Kim;Keunchang Jang;Joongbin Lim;Yangwon Lee
    • Korean Journal of Remote Sensing
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    • v.39 no.5_1
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    • pp.715-727
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    • 2023
  • To provide detailed and appropriate meteorological information in mountainous areas, the Korea Forest Service has established an Automatic Mountain Meteorology Observation Station (AMOS) network in major mountainous regions since 2012, and 464 stations are currently operated. In this study, we proposed an optimal kriging technique with lapse rate correction to produce gridded temperature data suitable for Korean forests using AMOS point observations. First, the outliers of the AMOS temperature data were removed through statistical processing. Then, an optimized theoretical variogram, which best approximates the empirical variogram, was derived to perform the optimal kriging with lapse rate correction. A 500-meter resolution Kriging map for temperature was created to reflect the elevation variations in Korean mountainous terrain. A blind evaluation of the method using a spatially unbiased validation sample showed a correlation coefficient of 0.899 to 0.953 and an error of 0.933 to 1.230℃, indicating a slight accuracy improvement compared to regular kriging without lapse rate correction. However, the critical advantage of the proposed method is that it can appropriately represent the complex terrain of Korean forests, such as local variations in mountainous areas and coastal forests in Gangwon province and topographical differences in Jirisan and Naejangsan and their surrounding forests.

Acceleration of computation speed for elastic wave simulation using a Graphic Processing Unit (그래픽 프로세서를 이용한 탄성파 수치모사의 계산속도 향상)

  • Nakata, Norimitsu;Tsuji, Takeshi;Matsuoka, Toshifumi
    • Geophysics and Geophysical Exploration
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    • v.14 no.1
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    • pp.98-104
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    • 2011
  • Numerical simulation in exploration geophysics provides important insights into subsurface wave propagation phenomena. Although elastic wave simulations take longer to compute than acoustic simulations, an elastic simulator can construct more realistic wavefields including shear components. Therefore, it is suitable for exploration of the responses of elastic bodies. To overcome the long duration of the calculations, we use a Graphic Processing Unit (GPU) to accelerate the elastic wave simulation. Because a GPU has many processors and a wide memory bandwidth, we can use it in a parallelised computing architecture. The GPU board used in this study is an NVIDIA Tesla C1060, which has 240 processors and a 102 GB/s memory bandwidth. Despite the availability of a parallel computing architecture (CUDA), developed by NVIDIA, we must optimise the usage of the different types of memory on the GPU device, and the sequence of calculations, to obtain a significant speedup of the computation. In this study, we simulate two- (2D) and threedimensional (3D) elastic wave propagation using the Finite-Difference Time-Domain (FDTD) method on GPUs. In the wave propagation simulation, we adopt the staggered-grid method, which is one of the conventional FD schemes, since this method can achieve sufficient accuracy for use in numerical modelling in geophysics. Our simulator optimises the usage of memory on the GPU device to reduce data access times, and uses faster memory as much as possible. This is a key factor in GPU computing. By using one GPU device and optimising its memory usage, we improved the computation time by more than 14 times in the 2D simulation, and over six times in the 3D simulation, compared with one CPU. Furthermore, by using three GPUs, we succeeded in accelerating the 3D simulation 10 times.