• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.475-482
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• 2001

Stadium stand could be led to significant dynamic response due to rhythmical activities of spectator. The dynamic loads induced by spectators movements are considered as static loads in design standard of many countries but these loads have dynamic characteristics. So, it is desirable to apply measured dynamic loads created by spectator activities and to analyze the dynamic behavior of stadium system. The precise investigation of the dynamic loads on stadium structures and the accurate analysis of dynamic behavior of stadium systems are demanded for effective design. As the floor mesh of stadium stand is refined, the number of nodes increase in numerical analysis. So it is difficult to analyze entire stadium structures and much more computer memory are necessary for vibration analysis of stadium system. In this study, the various dynamic loads induced by spectator movements are measured and analyzed. And new modeling method that reduce the nodal points of stadium systems are introduced. Vibration analysis of stadium system is executed to inspect the accuracy and the efficiency of proposed method in this paper.

• 한국기계가공학회지
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• 제8권3호
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• pp.21-26
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• 2009

The finite element analysis of metal forming processes often fails because of severe mesh distortion at large deformation. As the concept of meshless methods, only nodal point data are used for modeling and solving. As the main feature of these methods, the domain of the problem is represented by a set of nodes, and a finite element mesh is unnecessary. This computational methods reduces time-consuming model generation and refinement effort. It provides a higher rate of convergence than the conventional finite element methods. The displacement shape functions are constructed by the reproducing kernel approximation that satisfies consistency conditions. In this research, A meshless method approach based on the reproducing kernel particle method (RKPM) is applied with metal forming analysis. Numerical examples are analyzed to verify the performance of meshless method for metal forming analysis.

• Steel and Composite Structures
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• 제35권5호
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• pp.641-657
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• 2020

A unique lightweight string truss deployable bridge assembled by thin-walled fiber reinforced polymer (FRP) and metal profiles was designed for emergency applications. As a new structure, investigations into the static structural performance under the serviceability limit state are desired for examining the structural integrity of the developed bridge when subjected to unsymmetrical loadings characterized by combined torsion and bending. In this study, a full-scale experimental inspection was conducted on a fabricated bridge, and the combined flexural-torsional behavior was examined in terms of displacement and strains. The experimental structure showed favorable strength and rigidity performances to function as deployable bridge under unsymmetrical loading conditions and should be designed in accordance with the stiffness criterion, the same as that under symmetrical loads. In addition, a finite element model (FEM) with a simple modeling process, which considered the multi segments of the FRP members and realistic nodal stiffness of the complex unique hybrid nodal joints, was constructed and compared against experiments, demonstrating good agreement. A FEM-based numerical analysis was thereafter performed to explore the effect of the change in elastic modulus of different FRP elements on the static deformation of the bridge. The results confirmed that the change in elastic modulus of different types of FRP element members caused remarkable differences on the bending and torsional stiffness of the hybrid bridge. The global stiffness of such a unique bridge can be significantly enhanced by redesigning the critical lower string pull bars using designable FRP profiles with high elastic modulus.

• Asian Pacific Journal of Cancer Prevention
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• 제15권6호
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• pp.2815-2819
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• 2014

Background: The aim of this study was to evaluate the prognosis of patients with stage IA-IIB cervical carcinoma and to investigate a possible correlation of histology with prognosis. Materials and Methods: Two hundred fifty one patients with adenocarcinoma and squamous cell carcinoma (SCC) histology for FIGO (International Federation of Gynecology and Obstetrics) stage IA-IIB uterine cervical carcinomas at the Radiation Oncology Clinic of GH Okmeydan Training and Research Hospital between January 1996 and December 2006 were selected, analyzed retrospectively and evaluated in terms of general characteristics and survival. Disease-free survival (DFS) and overall survival (OS) was calculated using the Kaplan-Meier method and differences were compared with the log-rank test. Multivariate analysis using a Cox-proportional hazards model was used to adjust for prognostic factors and to estimate hazard ratio (HR) with 95% confidence interval (CI). Results: There was no differences between the two tumour types in age, stage, pelvic nodal metastasis, parametrial invasion, surgical margin status, DSI, LVSI, maximal tumor diameter, grade, and treatment modalities. 5-year OS and DFS were 73% and 77%, versus 64% and 69%, for SCC and adenocarcinoma, respectively (p> 0.05). Multivariate analysis revealed independent prognostic factors including pelvic nodal metastasis and resection margin status for OS (p=0.008, p=0.002, respectively). Conclusions: Prognosis of FIGO stage IA-IIB cervical cancer patients was found to be the same for those with adenocarcinoma and SCC.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.4853-4858
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• 2015

Background: Colorectal cancer is the most common gastrointestinal cancer in Oman with an increasing incidence. We here report the presenting features, treatment outcomes and survival in a University hospital in Oman and compare our data with regional and international studies. Materials and Methods: Medical records of patients with colorectal cancer were reviewed retrospectively between June 2000 and December 2013 and were followed until June 2014. Results: A total of 162 patients were diagnosed with colorectal cancer. The majority were males (58.6%), with a median age of 56 years. Rectum was involved in 29.6% of patients, followed by ascending and sigmoid colon. The majority of patients had stage III (42.6%) and stage IV (32.7%) disease at presentation. K-Ras status was checked for 79 patients, and 41 (51.9%) featured the wild type. Median relapse free survival was 22 months. Median overall survival for all patients was 43 months. Observed 5 year overall survival (OS) for stages I, II and III was 100%, 60% and 60% respectively. On Log rank univariate analysis, age, BMI, diabetes, hypertension, metformin use, stage, clinical nodal status for rectal cancer, pathological T and nodal status, site of metastasis, surgical intervention, chemotherapy, radiotherapy, chemotherapy regimen, no of cycles of chemotherapy, response, RFS, site of recurrence and administration of $2^{nd}$ line chemotherapy were significant factors affecting OS. On Cox regression multivariate analysis none of the factors independently affected the OS. Conclusions: The majority of patients present with advanced disease and at young age. The survival rates are comparable to the published regional and international literature.

• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.887-890
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• 2014

This study was undertaken to compare surgical outcomes and survival rates of patients with the 2009 International Federation of Gynecology and Obstetrics (FIGO) stage IIA1 versus IIA2 cervical cancer treated with radical hysterectomy and pelvic lymphadenectomy (RHPL). Patients with stage IIA cervical cancer undergoing primary RHPL between January 2003 and December 2012 at Chiang Mai University Hospital were retrospectively reviewed. The analysis included clinicopathologic variables, i.e. nodal metastasis, parametrial involvement, positive surgical margins, deep stromal invasion (DSI)), lymph-vascular space invasion (LVSI), adjuvant treatment, and 5-year survival. The chi square test, Kaplan-Meier method and log-rank test were used for statistical analysis. During the study period, 133 women with stage IIA cervical cancer, 101 (75.9 %) stage IIA1, and 32 (24.1 %) stage IIA2 underwent RHPL. The clinicopathologic variables of stage IIA1 compared with stage IIA2 were as follows: nodal metastasis (38.6% vs 40.6%, p=0.84), parametrial involvement (10.9% vs 15.6%, p=0.47), positive surgical margins (31.7% vs 31.3%, p=1.0), DSI (39.6% vs 53.1%, p=0.18), LVSI (52.5% vs 71.9%, p=0.05) and adjuvant radiation (72.3% vs 84.4%, p=0.33). With a median follow-up of 60 months, the 5-year disease-free survival (84.6% vs 88.7%, p=0.67) and the 5-year overall survival (83.4% vs 90.0%, P=0.49) did not significantly differ between stage IIA1 and stage IIA2 cervical cancer. In conclusion, patients with stage IIA1 and stage IIA2 cervical cancer have comparable rates of locoregional spread and survival. The need for receiving adjuvant radiation was very high in both substages. The revised 2009 FIGO system did not demonstrate significant survival differences in stage IIA cervical cancer treated with radical hysterectomy. Concurrent chemoradiation should be considered a more suitable treatment for patients with stage IIA cervical cancer.

• Advances in aircraft and spacecraft science
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• 제3권3호
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• pp.351-366
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• 2016

Macroperforations improve the sound absorption performance of porous materials in acoustic cavities and in waveguides. In an acoustic cavity, enhanced noise reduction is achieved using porous materials having macroperforations. Double porosity materials are obtained by filling these macroperforations with different poroelastic materials having distinct physical properties. The locations of macroperforations in porous layers can be chosen based on cavity mode shapes. In this paper, the effect of variation of macroporosity and double porosity in porous materials on noise reduction in an acoustic cavity is presented. This analysis is done keeping each perforation size constant. Macroporosity of a porous material is the fraction of area covered by macro holes over the entire porous layer. The number of macroperforations decides macroporosity value. The system under investigation is an acoustic cavity having a layer of poroelastic material rigidly attached on one side and excited by an internal point source. The overall sound pressure level (SPL) inside the cavity coupled with porous layer is calculated using mixed displacement-pressure finite element formulation based on Biot-Allard theory. A 32 node, cubic polynomial brick element is used for discretization of both the cavity and the porous layer. The overall SPL in the cavity lined with porous layer is calculated for various macroporosities ranging from 0.05 to 0.4. The results show that variation in macroporosity of the porous layer affects the overall SPL inside the cavity. This variation in macroporosity is based on the cavity mode shapes. The optimum range of macroporosities in poroelastic layer is determined from this analysis. Next, SPL is calculated considering periodic and nodal line based optimum macroporosity. The corresponding results show that locations of macroperforations based on mode shapes of the acoustic cavity yield better noise reduction compared to those based on nodal lines or periodic macroperforations in poroelastic material layer. Finally, the effectiveness of double porosity materials in terms of overall sound pressure level, compared to equivolume double layer poroelastic materials is investigated; for this the double porosity material is obtained by filling the macroperforations based on mode shapes of the acoustic cavity.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.473-480
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• 2005

Geometrical non-linearity due to the flexibility of cables must be considered efficiently in the dynamic analysis of cable structures. In this paper, formulation of tangent stiffness matrix of elastic catenary cable is derived by using relative nodal displacements, self-weight and unstressed cable length. Free vibration analysis of simply supported cable using elastic catenary cable elements is conducted and compared with that using truss elements. The result shows that elastic catenary cable elements are more compatible than truss elements in the case of analysis of cable structures. Furthermore, the characteristic of dynamic behaviors of cable structures by temporary unstability phenomenon is confirmed.

• 소성∙가공
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• 제8권1호
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• pp.108-115
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• 1999

In this paper, the analysis of cold forging in final state has been performed by using rigid-plastic FEM. For the analysis, the geometry and flow stress of the workpiece are required. One method to obtain the geometry is measurement of that made from experimet. To evaluate the flow stress, average effective strain is calculated from the load-stroke diagram by using energy method. The numerical test performed to show the validity of propose method. The analysis of PFIR, the precision forging of spurgear with inside relif, is performed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.486-490
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• 1997

Composite materials have varios complicated characteristics to the ply materials, ply orientations, ply stacking sequences and boundary conditions. Therefore, it is difficult to analysis composite materials. For efficient use of composite materials in engineering applications the dynamic behavior, that is, natural frequencies, nodal patterns should be informed. This study presents the experimental and FEM results for the free vibration of symmetrically and antisymmetrically laminated composite and hybrid composite rectangular plates. In order to demonstrate the validity of the experiment, FEM analysis using ANSYS was performed and natural frequencies experimentally obtined is compared with that calculated by FEM analysis. The results obtained from both experiment and FEM analysis show a good agreement.