• The Pure and Applied Mathematics
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• v.17 no.1
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• pp.93-106
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• 2010

We employ the methods of Lattice Dynamical System to establish a global model extending the Walrasian evolutionary cobweb model in an independent single local market to the global market evolution over an infinite chain of many local markets with interaction of each other through a diffusion of prices between them. For brevity of the model, we assume linear decreasing demands and logistic supplies with naive predictors, and investigate the traveling wave behaviors of global price dynamics and show that their dynamics are conjugate to those of H$\acute{e}$non maps and hence can exhibit complicated behaviors such as period-doubling bifurcations, chaos, and homoclic orbits etc.

• Journal of Korea Multimedia Society
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• v.11 no.12
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• pp.1649-1657
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• 2008

In this paper, to overcome the failure of binarization for the characters suffered from low contrast and non-uniform illumination in license plate character recognition system, we improved the binarization method by combining local thresholding with global thresholding and edge detection. Firstly, apply the local thresholding method to locate the characters in the license plate image and then get the threshold value for the character based on edge detector. This method solves the problem of local low contrast and non-uniform illumination. Finally, back-propagation Neural Network is selected as a powerful tool to perform the recognition process. The results of the experiments i1lustrate that the proposed binarization method works well and the selected classifier saves the processing time. Besides, the character recognition system performed better recognition accuracy 95.7%, and the recognition speed is controlled within 0.3 seconds.

• Communications of the Korean Mathematical Society
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• v.31 no.4
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• pp.695-701
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• 2016

Let I and J be two ideals of a commutative Noetherian ring R and M, N be two non-zero finitely generated R-modules. Let t be a non-negative integer such that $H^i_{I,J}(N)$ is (I, J)-minimax for all i < t. It is shown that the generalized local cohomology module $H^i_{I,J}(M,N)$ is (I, J)-Cofinite minimax for all i < t. Also, we prove that the R-module $Ext^j_R(R/I,H^i_{I,J}(N))$ is finitely generated for all $i{\leq}t$ and j = 0, 1.

• Journal of Korean Medical classics
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• v.35 no.2
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• pp.17-32
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• 2022

Objectives : To overcome limitations of previous diagnostic systems and constitutional medicine by suggesting a new perspective of constitutional medicine and a system of Yin Yang and Five Phases that is applicable to many diseases untreatable by biomedicine. Methods : The Life Structure Diagram which shows the different distribution of Yin Yang and Five Phases according to constitution, reflects the non-local and simultaneous characteristics of Yin Yang and Five Phases. It overcomes previous diagnostic systems and constitutional medicine which were local and segmented. Each constitutional types were determined through their defining deep fractal pulse patterns, for which appropriate acupuncture methods and formulas were suggested. Results & Conclusions : A more effective differentiation of constitution and treatment could be achieved through the Life Structure Diagram, which could overcome limitations of pre-existing diagnosis and treatments of Korean Medicine.

• Journal of Computational Design and Engineering
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• v.2 no.2
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• pp.113-118
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• 2015

An important problem in low-dose CT is the image quality degradation caused by photon starvation. There are a lot of algorithms in sinogram domain or image domain to solve this problem. In view of strong self-similarity contained in the special sinusoid-like strip data in the sinogram space, we propose a novel non-local filtering, whose average weights are related to both the image FBP (filtered backprojection) reconstructed from restored sinogram data and the image directly FBP reconstructed from noisy sinogram data. In the process of sinogram restoration, we apply a non-local method with smoothness parameters adjusted adaptively to the variance of noisy sinogram data, which makes the method much effective for noise reduction in sinogram domain. Simulation experiments show that our proposed method by filtering in both image and projection domains has a better performance in noise reduction and details preservation in reconstructed images.

• Computers and Concrete
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• v.31 no.5
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• pp.371-384
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• 2023

Precast roofing systems employing prestressed elements often serve as smart structural solutions for the construction of industrial buildings. The precast concrete elements usually employed are highly engineered, and often consist in thin-walled members, characterised by a complex behaviour in fire. The present study was carried out after a fire event damaged a precast industrial building made with prestressed beam and roof elements, and non-prestressed curved barrel vault elements interposed in between the spaced roof elements. As a consequence of the exposure to the fire, the main elements were found standing, although some locally damaged and distorted, and the local collapse of few curved barrel vault elements was observed in one edge row only. In order to understand and interpret the observed structural performance of the roof system under fire, a full fire safety engineering process was carried out according to the following steps: (a) realistic temperature-time curves acting on the structural elements were simulated through computational fluid dynamics, (b) temperature distribution within the concrete elements was obtained with non-linear thermal analysis in variable regime, (c) strength and deformation of the concrete elements were checked with non-linear thermal-mechanical analysis. The analysis of the results allowed to identify the causes of the local collapses occurred, attributable to the distortion caused by temperature to the elements causing loss of support in early fire stage rather than to the material strength reduction due to the progressive exposure of the elements to fire. Finally, practical hints are provided to avoid such a phenomenon to occur when designing similar structures.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1527-1532
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• 2023

The noise reduction algorithm using the non-local means (NLM) approach is very efficient in nuclear medicine imaging. In this study, the applicability of the NLM noise reduction algorithm in single-photon emission computed tomography (SPECT) images with a brain phantom and the optimization of the NLM algorithm by changing the smoothing factors according to various reconstruction methods are investigated. Brain phantom images were reconstructed using filtered back projection (FBP) and ordered subset expectation maximization (OSEM). The smoothing factor of the NLM noise reduction algorithm determined the optimal coefficient of variation (COV) and contrast-to-noise ratio (CNR) results at a value of 0.020 in the FBP and OSEM reconstruction methods. We confirmed that the FBP- and OSEM-based SPECT images using the algorithm applied with the optimal smoothing factor improved the COV and CNR by 66.94% and 8.00% on average, respectively, compared to those of the original image. In conclusion, an optimized smoothing factor was derived from the NLM approach-based algorithm in brain SPECT images and may be applicable to various nuclear medicine imaging techniques in the future.

• Radiation Oncology Journal
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• v.30 no.4
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• pp.153-157
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• 2012

Purpose: There has been no definite consensus on standard treatment, either local or systemic, for the Kaposi's sarcoma (KS). Radiotherapy (RT) can be a good local therapeutic choice especially in non-AIDS associated KS (NAKS) for its indolent behavior. Materials and Methods: Medical records of 17 KS patients treated with RT at the Seoul National University Hospital from February 1998 to January 2012 were retrospectively reviewed. One human immunodeficiency virus (HIV)+ patient with 3 lesions was excluded. The total number of the lesion was 23 among the 16 patients. The median follow-up period was 27.9 months. Correlation between response and variables was analyzed using the logistic regression model. Median age of the patients was 75 years. All the 23 lesions were located at the extremities. Fourteen (61%) of those had pain or local swelling as the initial presentation. Ten patients had possible causes of immunodeficiency and were regarded as iatrogenic, and other 6 were classic KS. Median dose of RT was 36 Gy. Results: No KS-related death was observed. Excluding 2 with short-term follow-up only, complete response and partial response were obtained in 2 (9%) and 19 (73%) lesions, respectively. Of those, 3 lesions underwent local progression. Six had out-of-field recurrence after RT. Symptom improvement was achieved in 13 (93%) of 14 patients. Grade 2 skin toxicities were found in 9 lesions but all got improvement after treatment. When divided into responsive and progressive group, free from progression was not related to any of the possible variables. Conclusion: RT is effective in local control of NAKS resulting great response rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.4
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• pp.153-156
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• 1984

A local area network(LAN) controller is designed according to non-persistent CSMA protocols. By meas of a buffer register, a microcomputer interfaces with the LAN controller. To keep bus utilization near the optimal efficiencies, the transmission intervals are adjusted as a function of $2^n$. A message in the form of a packet consisting of 128bytes is transitted to the bus. The maximum transmission rate of 19.2Kbps is obtained at layer 1.

• ETRI Journal
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• v.34 no.4
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• pp.572-582
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• 2012

The discrete Gaussian-Hermite moment (DGHM) is a global feature representation method that can be applied to square images. We propose a modified DGHM (MDGHM) method and an MDGHM-based scale-invariant feature transform (MDGHM-SIFT) descriptor. In the MDGHM, we devise a movable mask to represent the local features of a non-square image. The complete set of non-square image features are then represented by the summation of all MDGHMs. We also propose to apply an accumulated MDGHM using multi-order derivatives to obtain distinguishable feature information in the third stage of the SIFT. Finally, we calculate an MDGHM-based magnitude and an MDGHM-based orientation using the accumulated MDGHM. We carry out experiments using the proposed method with six kinds of deformations. The results show that the proposed method can be applied to non-square images without any image truncation and that it significantly outperforms the matching accuracy of other SIFT algorithms.