• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권11호
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• pp.4065-4083
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• 2021

Super-resolution can improve the clarity of low-resolution (LR) images, which can increase the accuracy of high-level compute vision tasks. Portable devices have low computing power and storage performance. Large-scale neural network super-resolution methods are not suitable for portable devices. In order to save the computational cost and the number of parameters, Lightweight image processing method can improve the processing speed of portable devices. Therefore, we propose the Enhanced Information Multiple Distillation Network (EIMDN) to adapt lower delay and cost. The EIMDN takes feedback mechanism as the framework and obtains low level features through high level features. Further, we replace the feature extraction convolution operation in Information Multiple Distillation Block (IMDB), with Ghost module, and propose the Enhanced Information Multiple Distillation Block (EIMDB) to reduce the amount of calculation and the number of parameters. Finally, coordinate attention (CA) is used at the end of IMDB and EIMDB to enhance the important information extraction from Spaces and channels. Experimental results show that our proposed can achieve convergence faster with fewer parameters and computation, compared with other lightweight super-resolution methods. Under the condition of higher peak signal-to-noise ratio (PSNR) and higher structural similarity (SSIM), the performance of network reconstruction image texture and target contour is significantly improved.

• 한국분무공학회지
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• 제8권1호
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• pp.1-8
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• 2003

The flow analysis of the axial fan of rotary burner was performed by SIMPLE(Semi Implicit Method for Pressure Linked Equations) algorithm and finite volume mothod performed in the case of 3-D, incompressible, turbulent flow. In this study, the coordinate transformation was adapted for the complex geometry of axial fan, and the standard $k-{\varepsilon}$ model and wall function method were used for analysis of turbulent flow. Multi-block grid system was used for flow field and divided into four domains such as the inlet, outlet, flow field of rotating vane, and tip clearance. Fan rotation was simulated by rotational motion using MRF(Multiple Rotating Reference Frame) in steady, incompressible state flow.

• 천문학회보
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• 제44권1호
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• pp.33.3-33.3
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• 2019

Automatic, yet reliable methods to find and classify barred galaxies are going to be more important in the era of large galaxy surveys. Here, we introduce a new approach to classify barred galaxies by analyzing the butterfly pattern that Buta & Block (2001) reported as a bar signature on the potential map. We make it easy to find the pattern by moving the ratio map from a Cartesian coordinate to a polar coordinate. Our volume-limited sample consists of 1698 spiral galaxies brighter than Mr = -15.2 with z < 0.01 from the Sloan Digital Sky Survey/DR7 visually classified by Ann et al. (2015). We compared the results of the classification obtained by four different methods: visual inspection, ellipse fitting, Fourier analysis, and our new method. We obtain, for the same sample, different bar fractions of 63%, 48%, 36%, and 56% by visual inspection, ellipse fitting, Fourier analysis, and our new approach, respectively. Although automatic classifications detect visually determined, strongly barred galaxies with the concordance of 74% to 86%, automatically selected barred galaxies contain different amount of weak bars. We find a different dependence of bar fraction on the Hubble type for strong and weak bars: SBs are preponderant in early-type spirals, whereas SABs are in late-type spirals. Moreover, the ellipse fitting method often misses strongly barred galaxies in the bulge-dominated galaxies. These explain why previous works showed the contradictory dependence of the bar fraction on the host galaxy properties. Our new method has the highest agreement with visual inspection in terms of the individual classification and the overall bar fraction. In addition, we find another signature on the ratio map to classify barred galaxies into new two classes that are probably related to the age of the bar.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제25권3호
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• pp.107-116
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• 2021

We introduce optimization algorithms using Bregman Divergence for solving non-negative matrix factorization (NMF) problems. Bregman divergence is known a generalization of some divergences such as Frobenius norm and KL divergence and etc. Some algorithms can be applicable to not only NMF with Frobenius norm but also NMF with more general Bregman divergence. Matrix Factorization is a popular non-convex optimization problem, for which alternating minimization schemes are mostly used. We develop the Bregman proximal gradient method applicable for all NMF formulated in any Bregman divergences. In the derivation of NMF algorithm for Bregman divergence, we need to use majorization/minimization(MM) for a proper auxiliary function. We present algorithmic aspects of NMF for Bregman divergence by using MM of auxiliary function.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권7호
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• pp.2010-2026
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• 2024

This work investigates the hybrid precoder scheme in a millimeter wave (mmWave) multi-user MIMO system. We study a sum rate maximization scheme by jointly designing the digital precoder and the analog precoder. To handle the non-convex problem, a block coordinate descent (BCD) method is formulated, where the digital precoder is solved by a bisection search and the analog precoder is addressed by the penalty dual decomposition (PDD) alternately. Then, we extend the proposed algorithm to the sub-connected schemes. Besides, the proposed algorithm enjoys lower computational complexity when compared with other benchmarks. Simulation results verify the performance of the proposed scheme and provide some meaningful insight.

• Spatial Information Research
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• 제19권2호
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• pp.37-46
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• 2011

최근 GIS 분야에서 공간 정보를 효과적으로 사용하기 위하여 다양한 원천 자료를 통합하는 것이 중요한 화두로 대두되고 있다. 일반적으로 공간 정보의 통합은 대응 공간 객체를 탐색하고 각 객체와 연동되어 있는 정보를 결합함으로써 수행된다. 하지만 어떤 공간 객체에 대응되는 다른 공간 객체를 탐색하는 것은 매우 어려운 문제로, 서로 다른 공간 객체를 탐색하기 위한 매칭 방법이 많이 연구되고 있다. 따라서 본 연구는 서로 다른 건물 데이터 셋의 통합 과정에서 좌표 변환 이후에도 잔존하는 국지적 위치 오차를 고려하여 대응 공간 객체를 탐색할 수 있는 방법을 개발하는 것을 목적으로 한다. 이러한 목적을 위해 두 지도를 좌표 변환하고 중첩 및 위치 오차가 유사한 단위 구역을 생성한 후, 위치 오차가 유사한 단위 구역 내의 건물들을 매칭하기 위하여 유사도와 ICP(iterative closest point) 알고리즘을 이용하였다. 그리고 이러한 제안된 방법의 활용 가능성을 실험을 통하여 알아보았다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권1호
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• pp.20-39
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• 2020

This paper considers a downlink multi-carrier cooperative non-orthogonal multiple access (NOMA) transmission, where no direct link exists between the far user and the base station (BS), and the communication between them only relies on the assist of the near user. Firstly, the BS sends a superimposed signal of the far and the near user to the near user, and then the near user adopts simultaneous wireless information and power transfer (SWIPT) to split the received superimposed signal into two portions for energy harvesting and information decoding respectively. Afterwards, the near user forwards the signal of the far user by utilizing the harvested energy. A minimum data is required to ensure the quality of service (QoS) of the far user. We jointly optimize power allocation, subcarrier allocation, time allocation, the power allocation (PA) coefficient and the power splitting (PS) ratio to maximize the number of data bits received at the near user under the energy causality constraint, the minimum data constraint and the transmission power constraint. The block-coordinate descent method and the Lagrange duality method are used to obtain a suboptimal solution of this optimization problem. In the final simulation results, the superiority of the proposed NOMA scheme is confirmed compared with the benchmark NOMA schemes and the orthogonal multiple access (OMA) scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권4호
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• pp.1373-1391
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• 2022

We investigate mobile multiple-input multiple-output (MIMO) molecular communication via diffusion (MCvD) system which is consisted of two source nodes, two destination nodes and one relay node in the mobile three-dimensional channel. First, the combinations of decode-and-forward (DF) relaying protocol and network coding (NC) scheme are implemented at relay node. The adaptive thresholds at relay node and destination nodes can be obtained by maximum a posteriori (MAP) probability detection method. Then the mathematical expressions of the average bit error probability (BEP) of this mobile MIMO MCvD system based on DF and NC scheme are derived. Furthermore, in order to minimize the average BEP, we establish the optimization problem with optimization variables which include the ratio of the number of emitted molecules at two source nodes and the initial position of relay node. We put forward an iterative scheme based on block coordinate descent algorithm which can be used to solve the optimization problem and get optimal values of the optimization variables simultaneously. Finally, the numerical results reveal that the proposed iterative method has good convergence behavior. The average BEP performance of this system can be improved by performing the joint optimizations.

• 대한치과보철학회지
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• 제37권3호
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• pp.358-374
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• 1999

This study measured the relative displacements of the five-unit fixed partial dentures as cast with the same fixed partial dentures sectioned and assembled by investment-soldering, solder-ing stand-soldering, and cast-joining techniques A total of fifteen specimens using a type IV gold alloy were one-piece cast as control and then sectioned and assembled five test specimens for each method were prepared. A computerized three dimensional coordinate measuring machine and specially designed cylinder for this study were used. Displacement was defined by six displacement variables for the each of cylinders incorporated in each casting: three component displacements(${\Delta}Lx,\;{\Delta}Ly,\;and\;{\Delta}Lz$) and rotational displacements(${\Delta}{\theta}x,\;{\Delta}{\theta}y,\;{\Delta}{\theta}z$). The global displacement was computed using the mathematical formula ${\Delta}R$ = Global displacement =$\sqrt{{(x'-x)}^2+{(y'-y)}^2+{(z'-z)}^2}$ Under the conditions of this study, the following conclusions were drawn: 1. The investment-soldering group showed the largest mean value of final global displacements, followed by stand-soldering group, cast-joining group and one-piece cast group. However, between the mean values of final global displacement for the cast-joining group and one-piece cast group, there was no significant difference. 2. For investment-soldering and stand-soldering groups, the greater global displacements were recorded in soldering phase than in indexing or investing phase. 3. For one-piece cast group, the displacements occured mostly in the casting phase. And for cast-joining group, there was no significant difference in global displacements among the fabricating procedures. 4. Intercentroidal distance decreased in framework-patterning, solder-indexing, solder-standing, and soldering phases, but increased in investment block-investing and casting phases. 5 Specially designed cylinder for touch-trigger type coordinate measuring machine was validated.

• 자원환경지질
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• 제53권3호
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• pp.271-285
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• 2020

본 연구는 절리의 기하학적 속성이 절리성 암반의 변형 특성에 미치는 영향을 평가하기 위하여 삼차원 불연속절리망(DFN; discrete fracture network) 시스템에 대한 개별요소법 기반의 응력-변형 해석과 관련된 수치실험을 수행하였다. 1~2 개의 확정적 방향성을 갖는 절리군을 사용하여 절리의 빈도와 길이분포를 달리하며 추계론적으로 생성한 총 12개의 1000㎥ 정육면체 DFN 블록에 대하여 삼차원 직교좌표계의 축 방향에 따른 변형계수가 산정되었다. 또한, 일부 DFN 블록은 삼차원상에서 매 30° 간격의 선주향 및 선경사 방향을 축차응력 방향으로 설정하고 변형계수를 산정하였다. 절리의 길이가 증가할수록 DFN 블록의 변형계수는 더욱 저감되는 것으로 평가되었다. 절리의 빈도 증가는 절리의 길이가 짧아서 상대적으로 암교 효과가 큰 경우 DFN 블록의 변형계수 저감에 유의미한 영향을 미치지 못 할 가능성도 있지만 절리길이가 길수록 절리빈도의 증가가 DFN의 이방적 변형계수에 지대한 영향을 미치는 것으로 평가되었다. 절리의 길이와 빈도 변화에 따른 이방적 변형계수의 변화는 DFN에 분포하는 절리군의 개수 및 방향성에 크게 좌우된다. DFN 블록의 변형 특성은 삼차원상의 방향에 따라 다르게 발현되는 것으로 평가되었다. 마지막으로 본 연구는 절리의 기하학적 속성이 고려된 응력-변형 해석을 위한 수치해석 절차를 제시하였으며 현장규모의 실무 적용을 위한 방법론에 대하여 토의하였다.