• Coupled systems mechanics
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• v.7 no.6
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• pp.755-774
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• 2018

The Ritz method is known as very successful strategy for discretizing continuous problems, but it has never been used for solving systems of algebraic equations. The Iterated Ritz Method (IRM) is a novel iterative solver based on the discretized Ritz procedure applied at each iteration step. With an appropriate choice of coordinate vectors, the method may be efficient in linear, nonlinear and optimization problems. Additionally, some iterative methods can be explained as special cases of this approach, which helps to understand advantages and limitations of these methods and gives motivation for their improvement in sense of IRM. In this paper, some ideas for generation of efficient coordinate vectors are presented. The algorithm was developed and tested independently and then implemented into the open source program FEAP. Method has been successfully applied to displacement based (even ill-conditioned) models of structural engineering practice. With this original approach, a new iterative solution strategy has been opened.

• Korean Journal of Mathematics
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• v.31 no.4
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• pp.419-431
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• 2023

In this paper, we propose an iterative method for a symmetric interior penalty Galerkin method for heterogeneous elliptic problems. The iterative method consists mainly of two parts based on a non-overlapping domain decomposition approach. One is an intermediate preconditioner constructed by understanding the properties of the discontinuous finite element functions and the other is a preconditioning related to the dual-primal finite element tearing and interconnecting (FETI-DP) methodology. Numerical results for the proposed method are presented, which demonstrate the performance of the iterative method in terms of various parameters associated with the elliptic model problem, the finite element discretization, and non-overlapping subdomain decomposition.

• Food Science and Preservation
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• v.11 no.3
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• pp.304-312
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• 2004

Early harvested Satsuma mandarin (Citrus unshiu) was treated with hot air at 45$^{\circ}C$ for 2, 4, and 6 hours and stored at 5$^{\circ}C$ for 3 weeks and additional one week at 18$^{\circ}C$ (simulated shelf-life) in order to examine the effect of mild heat treatment on the storage quality of the citrus fruits. Quality attributes of the sample fruits evaluated during storage included the respiration rate, internal gas composition, pH, titratable acidity, soluble solids content, flesh weight loss, firmness, peel color, decay ratio, and sensory properties. The initial respiration rates, just after hot air treatment, were significantly higher in the heat-treated fruits compared to the untreated. However, during storage at 5$^{\circ}C$, the respiration rates showed a similar level in all treatments. Internal gas composition exhibited no significant difference between the heat-treated and untreated samples. Hot air treatment also exerted no significant effects on the pH, titratable acidity, soluble solid contents, flesh weight loss, firmness, and peel color of the fruits during the whole storage period. The decay ratio was manifestly lower in the heat-treated fruits than the untreated. For sensory attributes including visual and organoleptic quality, no significant difference was observed among sample fruits. Results suggested that mild heat treatment with hot air at 45$^{\circ}C$ for 4-6 hours could be used as an effective preconditioning method to keep the postharvest quality of Satsuma mandarin by reducing the decay incidence remarkably during storage.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.4
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• pp.201-206
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• 2004

Mitochondrial ATP-sensitive potassium $(mitoK_{ATP})$ channels play a role in early and late ischemic preconditioning. Nevertheless, the subunit composition of $mitoK_{ATP}$ channels remains unclear. In this study, we investigated the subunit composition of $mitoK_{ATP}$ channels in mitochondria isolated from rat cardiac myocytes. Mitochondria were visualized using the red fluorescence probe, Mitrotracker Red, while $mitoK_{ATP}$ channels were visualized using the green fluorescence probe, glibenclamide-BODIPY. The immunofluorescence confocal microscopy revealed the presence of Kir6.1, Kir6.2 and SUR2 present in the cardiac mitochondria. Western blot analysis was carried to further investigate the nature of $mitoK_{ATP}$ channels. For SUR proteins, a 140-kDa immunoreactive band that corresponded to SUR2, but no SUR1 was detected. For Kir6.2, three bands $({\sim}44,\;{\sim}46,\;and\;{\sim}30\;kDa)$ were detected, and a specific ${\sim}46-kDa$ immunoreactive band corresponding to Kir6.1 was also observed. These observations suggest that the subunits of $mitoK_{ATP}$ channels in rat myocytes include Kir6.1, Kir6.2, and a SUR2-related sulfonylurea-binding protein.

• Archives of Plastic Surgery
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• v.34 no.2
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• pp.163-168
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• 2007

Purpose: The flap delay is a widely used technique to increase the flap survival. Dexamethasone is a well-known drug to have a positive impact on the flap survival. The objective of this study is to investigate the dual synergic effect of epinephrine as a chemical delay agent plus dexamethasone on the TRAM flap survival in rat model. Methods: Forty Sparague-Dawley rats were divided into 4 groups evenly and a right inferior epigastic vessel pedicled TRAM flap, sized $5.0{\times}3.0cm$, was elevated on each upper abdomen. In the control group(N=10), 2 ml saline was injected on transverse abdominis muscle for a week before the flap elevation. In surgical delay group(N=10) all superior pedicles and left inferior pedicle were ligated a week before the flap elevation. In epinephrine group (N=10), 1 : 50000 epinephrine mixed saline was injected to transverse abdominis muscle every day for a week before flap elevation. In epinephrine plus dexamethasone group (N=10), the same procedure as that of epinephrine group was conducted for a week and 2.5 ml/kg dexamethasone was injected transverse abdominis muscle 2 hours before the flap elevation. On the seventh day after flap elevation, the survival area of flaps were measured and the vessel numbers in upper dermis of flap were counted through histologic slides. Results: The results were as follows: the mean percentage of the flap survival area of surgical delay group ($60.5{\pm}2.44%$), epinephrine group ($75{\pm}4.43%$), and epinephrine plus dexamethasone group ($87{\pm}1.94%$) were higher than that of the control group ($35{\pm}6.06%$) significantly(p<0.05). In case of the vessel number though histologic slides, epinephrine group ($79.3{\pm}5.57$) and epinephrine plus dexamethasone group ($96.3{\pm}14.05$) were higher than that of the control group ($44.8{\pm}8.82$) significantly(p<0.05), but the surgical delay group ($54{\pm}4.23$) showed no significant difference (p>0.05) compared to that of the control group. Conclusion: The results indicated that epinephrine plus dexamethasone injection before the flap elevation could be used to increase the TRAM flap survival area in rat model.

• The Transactions of the Korea Information Processing Society
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• v.2 no.6
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• pp.960-968
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• 1995

In this paper we present a reordering scheme that could lead to efficient vectorization of the preconditioners for the large sparse linear systems arising from partial differential equations on the CRAY-2, This reordering scheme is a line version of the conventional red/black ordering. This reordering scheme, coupled with a variant of ILU(Incomplete LU) preconditioning, can overcome the poor rate of convergence of the conventional red/black reordering, if relatively large number of fill-ins were used. We substantiate our claim by conducting various experiments on the CRAY-2 machine. Also, the computation of the Frobenius norm of the error matrices agree with our claim.

• Macromolecular Research
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• v.15 no.4
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• pp.370-378
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• 2007

Mechanical stimulation is known to activate several cellular signal transduction pathways, leading to the induction of signaling molecules and extracellular matrix (ECM) proteins, thereby modulating cellular activities, such as proliferation and survival. In this study, primary human dermal fibroblasts (HDFs) were seeded onto chitosan-based scaffolds, and then cultured for 3 weeks in a bioreactor under a cyclic strain of 1 Hz frequency. Compared to control samples cultured under static conditions, the application of a cyclic strain stimulated the proliferation of HDFs in I week, and by week 3 the thickness of the cell/scaffold composites increased 1.56 fold. Moreover, immunohistochemical staining of the culture media obtained from the cell/scaffold samples subjected to the cyclic strain, revealed increases in the expression and secretion of ECM proteins, such as fibronectin and collagen. These results suggest that the preconditioning of cell/scaffold composites with a cyclic strain may enhance the proliferation of HDFs, and even facilitate integration of the engineered artificial dermal tissue into the host graft site.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.42-46
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• 2009

For understanding of high performance liquid rocket engine operating at high pressure, dynamic characteristics of liquid oxygen in a swirl injector operating at supercritical conditions has been numerically investigated. Turbulent numerical model is based on large eddy simulation and contains full conservation laws including Soave modification of Redlich-Kwong equation of state and Chung's model. Preconditioning method is applied to get an effective convergence rate. Numerical analysis results are compared with the one that ideal equation of state applied to. Differences of thermodynamic properties and mixing dynamics are investigated at liquid phase area inside injector and combustion chamber.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.919-921
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• 2015

The edge is widely utilized as a preconditioning process in order to simplify the images in several fields such as the object recognition and detection. The edge detection methods which are generally known include the methods of Sobel, Roberts and Laplacian. However, such current methods have an advantage that the implementation is simple but bring more less an insufficient result since they use the fixed weighting mask. Therefore, an algorithm using the modified morphology is proposed in order to supplement such problems of the current edge detection methods and obtain the excellent edge detection, and also a simulation using this algorithm is conducted to compare with such current methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.267-269
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• 2015

In the modern society, the images provide the most effective information in multi-devices and the edge includes important feature information in such images. This edge is used as an essential preconditioning process in several application fields and many studies have been carried out in order to obtain the excellent images. The methods of Sobel and Roberts which are generally known are simple to implement the images but bring more or less insufficient processing result. Thus, this paper proposed an edge detection algorithm using the area averaging of segmented mask in order to supplement the problems of the current methods and compared it with such current methods.