• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.2
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• pp.141-159
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• 2009

In this article, we consider a weighted CVT-based reduced-order modelling for Burgers equation. Brief review of the CVT (centroidal Voronoi tessellation) approaches to reduced-order bases are provided. In CVT-reduced order modelling, we start with a snapshot set just as is done in a POD (Proper Orthogonal Decomposition)-based setting. So far, the CVT was researched with uniform density ($\rho$(y) = 1) to determine the basis elements for the approximatin subspaces. Here, we shall investigate the technique of CVT with nonuniform density as a procedure to determine the basis elements for the approximating subspaces. Some numerical experiments including comparison of two CVT (CVT-uniform and CVT-nonuniform)-based algorithm with numerical results obtained from FEM(finite element method) and POD-based algorithm are reported.

• Tribology and Lubricants
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• v.22 no.1
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• pp.20-25
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• 2006

The stress behavior analysis of a-rings and packing for a LPG filling unit has been presented using a finite element analysis technique by non-linear MSC/MARC program. The sealing performance and endurance of a-rings and packing are affected by working conditions such as filling pressure, friction coefficient, compression ratio, and material properties. The elastomeric polymers of O-rings and packing are nitrile butadiene rubber (NBR) and polytetrafluoroethylene (PTFE), which are selected as proper materials of a-rings and packing based on the stress analysis results. The calculated FEM results showed that the proper material of O-ring is NBR as a secondary sealing component and the recommended material of packing is PTFE as a primary sealing unit during a LPG filling process.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.197-204
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• 2001

The purpose of this paper is to develope the evaluation technique to find proper elastic constants that characterize the material nonlinearity of structural membrane. The stress-strain curves of membrane material show strong nonlinearity. But generally the analysis is carried out under the assumption on material linear and geometrical nonlinear method. Because, it is very difficult to evaluate proper tangential stiffness. This paper use multi-step-linear approximation method taking the concept of effective stress for the evaluation of stiffness of membrane material, and then compare the results between linear and nonlinear analysis. Also. it shows better results than linear method

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.396-398
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• 2005

At present, fatigue design of welded structures is primarily based on nominal stress or hot spot stress approach with a series of classified weld S-N curves. However, these methods are known to possess drawbacks, such as difficulty associated with defining proper nominal stress and the finite element sue sensitivity etc. Recently, a mesh-size insensitive structural stress definition is proposed by Battelle that gives a stress state at weld toe with relatively large mesh size. The structural stress definition is based on the elementary structural mechanics theory and provides an effective measure of a stress state in front of weld toe. As an experimental validation of the structural stress method in obtaining the fatigue strength of weldments, a series of experiment is carried out for various sizes of weldments. Based on the result from this study, it is expected to develop a more precise fatigue strength evaluation technique and to save time period required in the fatigue design of ship and offshore structures.

• Transactions of Materials Processing
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• v.12 no.5
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• pp.457-464
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• 2003

In the powder compact melting technique, proper precursor fabrication is very important because density distribution after foaming and foamability are determined during precursor fabrication process. The fabrication of the precursor has to be performed very carefully because any residual porosity or other defects will lead to poor results in further processing. In order to evaluate the effect of the compaction parameters on the kinetics of the foaming process, a series of experiments were performed. In this study, aluminium foams with a closed cell structure were fabricated by using both the powder compact method and the induction heating process. A proper induction coil was designed to obtain a uniform temperature distribution over the entire cross sectional area of precursor. To establish the foamable precursor fabrication conditions, effects of process parameters such as the titanium hydride content (0.3∼1.5 wt.%), pressing pressure of the foamable precursor (50∼150kN) on the pore morphology were investigated.

• Journal of the Korean Society of Radiology
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• v.83 no.4
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• pp.783-791
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• 2022

The radiation emitted during radiological examinations can be harmful to the human body, but the technique is still used because it is helpful to the patient. Therefore, radiologic examinations must follow radiation protection principles such as justification and optimization, and only minimal required re-examinations should be performed. Proper use of radiation in the medical field can be achieved by proper education of individuals from multiple medical fields.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.317-324
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• 2000

In this paper, we propose an interpolation technique to rain attenuation data which represents dynamic characteristics by time variations. By using this technique, it is possible to sample the rain attenuation data at an arbitrary time interval, and thus it would play an important role in developing adaptive transmission scheme for countermeasuring rain attenuation. We propose the interpolation technique which can synthesizes rain attenuation data by extracting the most proper parameters required to emulate the dynamic characteristics of rain attenuation. Interpolation results to measured data of I minute time interval will be demonstrated, and it is shown that more exact performance evaluation of adaptive transmission scheme to countermeasure rain attenuation can be achieved.

• The Korean Journal of Pain
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• v.10 no.1
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• pp.89-92
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• 1997

Neurolytic splanchnic nerve block is effective for treatment of intractable upper abdominal cancer pain. Conventional approach for splanchnic nerve block is conducted in the prone position to ensure proper orientation and to allow insertion of needles on each side of the vertebral body. However, the prone position has some technical disadvantages as this position is frequently poorly tolerated by a majority of patients with advanced cancer due to severe abdominal pain, ascites and so on. Male patient, 53-year old with transverse colon cancer, carcinomatosis peritonei and $L_1,\;L_2$ vertebral body metastasis, was admitted for treatment of severe right upper quadrant and right iliac crest pain. We performed neurolytic splanchnic nerve block with transdiscal technique in the lateral decubitus position under fluoroscopic guidance, and well noted the usefulness and the advantage of this technique. The benefits of this technique are safe, simple and effective because the lateral position is better tolerated by patients and makes bony landmarks more accessible during fluoroscopy.

• Archives of Plastic Surgery
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• v.45 no.5
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• pp.484-489
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• 2018

Large and ptotic breast reconstruction in patients who are not candidates for a transverse rectus abdominalis myocutaneous flap and revision surgery for the contralateral breast remains challenging. We developed a novel breast reconstruction technique using a latissimus dorsi myocutaneous (LD m-c) flap set at the posterior aspect of the reconstructed breast, combined with an anatomical silicone breast implant (SBI), following tissue expander surgery. We performed the proposed technique in four patients, in whom the weight of the resected tissue during mastectomy was >500 g and the depth of the inframammary fold (IMF) was >3 cm. After over-expansion of the lower portion of the skin envelope by a tissue expander, the LD m-c flap was transferred to cover the lower portion of the breast defect and to achieve a ptotic contour, with the skin paddle set at the posterior aspect of the reconstructed breast. An SBI was then placed in the rest of the breast defect after setting the LD m-c flap. No major complications were observed during the follow-up period. The proposed technique resulted in symmetrical and aesthetically satisfactory breasts with deep IMFs, which allowed proper fitting of the brassiere, following large and ptotic breast reconstruction.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.577-580
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• 2004

To overcome with large size noise source distribution network design difficulty in interferometric radiometer system, especially for sub-Y-type array, a new on-board calibration technique using noise re-radiation is proposed in this paper. The suggested calibration technique is using noise re-radiation effect of center antenna after noise source injection from matched load. This approach is especially proper to sub-Y-type array interferometric synthetic aperture radiometer in mm-wave frequency band. Compared with noise injection network of a conventional synthetic aperture radiometer, the system mass, volume, and hardware complexity is reduced and cost-effective. Only one internal noise source, matched load, is used for injection using noise re-radiation technique a small set of sub-Y receiver channels is calibrated. Detailed calibration scenario is discussed and simulation results about noise re­radiation effect are presented.