• Journal of Korean Association for Spatial Structures
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• v.4 no.2 s.12
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• pp.63-71
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• 2004

The structural space is gradually wide and is wanting agreeable environment by the requirement and necessity of people who lives modem stage. The building coincides with such requirements and is the high rise building actual circumstances which is doing ultra-large. The confirmed report of the technology to organize great merit is becoming currently considerably important issue in constructing a building field. Thus, this paper examine closely for nonlinear unstable taking a picture uneasiness height of prosperity considering to initial imperfection by a numerical method with a space frame structure of discrete system in large space structure. Based on previous investigation method, this paper induce nodal stiffness matrix of solid truss elements considering geometrical nonlinear using finite element method. In this paper, three types of space structure considered; i) 1-free node space structure, ii) 2-free node space structure, iii) multi-free node space structure. It apply the above examples to a nonlinear program, next, grasp the characteristic of an unstable conduct and the result was a clearing low.

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.345-371
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• 1994

Restorative procedures can lead to weakening tooth due to reduction and alteraton of tooth structure. It is essential to prevent fractures to conserve tooth. Among the several parameters in cavity designs, cavity isthmus and depth are very important. In this study, MO amalgam cavity was prepared on maxillary first premolar. Three dimensional. finite element models were made by serial photographic method and cavity depth(1.7mm, 2.4mm) and isthmus (11 4, 1/3, 1/2 of intercuspal distance) were varied. linear, eight and six-nodal, isoparametric brick elements were used for the three dimensional finite element model. The periodontal ligament and alveolar bone surrounding the tooth were excluded in these models. Three types model(B, G and R model) were developed. B model was assumed perfect bonding between the restoration and cavity wall. Both compressive and tensile forces were distributed directly to the adjacent regions. G model(Gap Distance: 0.000001mm) was assumed the possibility of play at the interface simulated the lack of real bonding between the amalgam and cavity wall (enamel and dentin). When compression occurred along the interface, the forces were transferred to the adjacent regions. However, tensile forces perpendicular to the interface were excluded. R model was assumed non-connection between the restoration and cavity wall. No force was transferred to the adjacent regions. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, von Mises stress, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as follows: 1. G model showed stress and strain patterns between Band R model. 2. B model and G model showed the bending phenomenon in the displacement. 3. R model showed the greatest amount of the displacement of the buccal cusp followed by G and B model in descending order. G model showed the greatest amount of the displacement of the lingual cusp followed by B and R model in descending order. 4. B model showed no change of the displacement as increasing depth and width of the cavity. G and R model showed greater displacement of the buccal cusp as increasing depth and width of the cavity, but no change in the displacement of the lingual cusp. 5. As increasing of the width of the cavity, stress and strain were not changed in B model. Stress and strain were increased on the distal marginal ridge and buccopulpal line angle in G and R model. The possibility of the tooth fracture was increased. 6. As increasing of the depth of the cavity, stress and strain were not changed in B and G model. Stress and strain were increased on the distal marginal ridge and buccopulpal line angle in R model. The possibility of the tooth fracture was increased.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.432-461
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• 1995

The basic principles in the design of Class II amalgam cavity preparations have been modified but not changed in essence over the last 90 years. The early essential principle was "extension for prevention". Most of the modifications have served to reduce the extent of preparation and, thus, increase the conservation of sound tooth structure. A more recent concept relating to conservative Class II cavity preparations involves elimination of occlusal preparation if no carious lesion exists in this area. To evaluate the ideal ClassII cavity preparation design, if carious lesion exists only in the interproximal area, three cavity design conditions were studied: Rodda's conventional cavity, simple proximal box cavity and proximal box cavity with retention grooves. In this study, MO amalgam cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method. Linear, eight and six-nodal, isoparametric brick elements were used for the three dimensional finite element model. The periodontal ligament and alveolar bone surrounding the tooth were excluded in these models. Three types model(B option, Gap option and R option model) were developed. B option model was assumed perfect bonding between the restoration and cavty wall. Gap option model(Gap distance: $2{\mu}m$) was assumed the possibility of play at the interface simulated the lack of real bonding between the amalgam and cavity wall (enamel and dentin). R option model was assumed non-connection between the restoration and cavty wall. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as followed. 1. Rodda's cavity form model showed greater amount of displacement with other two models. 2. The stress and strain were increased on the distal marginal ridge and buccopulpal line angle in Rodda's cavity form model. 3. The stress and strain were increased on the central groove and a part of distal marginal ridge in simple proximal box model and proximal box model with retention grooves. 4. With Gap option, Rodda's cavity form model showed the greatest amount of the stress on distal marginal ridge followed by proximal box model with retention grooves and simple proximal box model in descending order. 5. With Gap option, simple proximal box model showed greater amount of stress on the central groove with proximal box model with retention grooves. 6. Retention grooves in the proximal box played the role of supporting the restorations opposing to loads.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.700-704
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• 2010

Background: For staging primary lung cancer, integrated positron emission tomography/computed tomography (PET/CT) imaging is popular. The purpose of this study was to evaluate the accuracy of PET/CT scanning in lymph nodal staging of lung cancer. Material and Method: We studied 48 patients who had received CT, PET/CT and pulmonary resections due to primary non-small cell lung cancer in our hospital between January 2006 and August 2009. Mediastinal lymph nodes were classified as superior mediastinal nodes, aortic nodes, inferior mediastinal nodes, or N1 nodes. We compared the power of CT and PET/CT for diagnosing pulmonary lymph nodes for each of the four types of nodes. Result: PET/CT was more sensitive than CT for all groups except inferior mediastinal nodes. However, the differences were not significant (McNemar's test: superior mediastinal nodes, p=0.109; aortic nodes, p=1.000; inferior mediastinal nodes, p=0.625, N1 nodes, p=0.424). Conclusion: The accuracy of PET/CT is similar to that of CT alone for staging lymph nodes. The two imaging modalities might be used as complementary, cooperative tools. We expect that integrated PET/CT will be found to be significantly mmore sensitive after more trials are done and more data is accumulated.

• Tuberculosis and Respiratory Diseases
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• v.50 no.5
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• pp.557-567
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• 2001

Background : Tumor angiogenesis is required for tumor growth and metastasis. In this study, we investigated the correlation between the intensity of angiogenesis and stage, nodal status, histologic type, metastasis and survival rate of non-small cell lung cancer. Method : Formalin fixed, paraffin embedded surgical specimens of 45 patients who had surgically resected primary non-small cell lung cancers without pre or post operative adjuvant chemotherapy or radiotherapy were examined. The microvessel count(MVC) was demonstrated by immunohistochemical staining for CD31(platelet endothelial cell adhesion molecule, PECAM). Results : Microvessel counts(MVCs) in stage IIIA and IIIB were higher than in stage I and II(p<0.05). The MVC in patients with lymph node metastasis was higher than that in patients without lymph node metastasis, although the difference was not statistically significant(p>0.05). However, in adenocarcinoma, the MVC in patients with lymph node metastasis was significantly higher than that seen in patients without lymph node metastasis(p<0.05). The MVC in adenocarcinoma was higher than that in squamous cell carcinoma(p<0.05). The difference between the MVCs of adenocarcinoma and squamous cell carcinoma was not statistically significant in stage I and II or N0 stage(p>0.05). However, in stage IIIA and IIIB or N1~3 stage, the MVC in adenocarcinoma was higher than that in squamous cell carcinoma(p<0.05). MVC was more increased when metastasis developed within 12 months. In the same histologic type and stage, the duration of survival time in patients with high MVC was shorter than in patients with low MVC, however the difference was not statistically significant(p>0.05). The survival rate in patients with high MVCs was lower than that in patients with low MVCs(P<0.05). Conclusion : In non-small cell lung cancer, MVC correlated relatively well with pathologic stage, nodal status(limited in patients with adenocarcinoma), histologic type, postoperative metastasis and survival rate. However, in the same histologic type and stage, MVC was not significantly related to the duration of survival. Therefore the assessment of the intensity of angiogenesis in non-small cell lung cancer may be helpful in predicting prognosis and in selecting patients for systemic adjuvant therapy of potential metastasis according to the results.

• Korean Journal of Head & Neck Oncology
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• v.23 no.1
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• pp.9-14
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• 2007

Background and Objectives：The prevalence rate of laryngeal cancer, the cancer known as good prognosis in comparison to other malignancy, accounts for 1% of all malignancy in Korea(Korea Central Cancer Registry, 2002). The purpose of this study is to review the treatment experiences of our hospital and find prognostic factors in laryngeal cancer patients. Materials and Method：A retrospective study was conducted on 244 laryngeal cancer patients between January 1987 through December 2003. Age, sex, TNM stage, 5 year survival rate, prognostic factors were analyzed. Results：The overall 5 year survival rate was 57.8%. The 5 year survival rate according to primary site and treatment method showed supraglottis 49.5%, glottis 79.2%, transglottis 28.2% and surgery only 71.4%, radiotherapy only 58.1%, post operative radiotherapy 47.2%, salvage operation 52.0%. There was no statistically significant difference among the results obtained by 4 different methods of treatment. but in supraglottis, surgery only has good 5 year survival rate(75.8%) compare to radiotherapy only(38.3%), postoperative radiotherapy(20.0%), salvage operation(43.7%) and there was statistically significant difference. The 5 year survival rate according to clinical stage and T status showed 84.1%, 37.2%, in stage I & II, III & IV respectively, 72.9%, 37.5% in stage T1 & T2, T3 & T4 respectively. The 5 year survival rate according to nodal status showed N(-)77.1%, N(+)35.6%. Conclusion：Those patient with early T stage, early clinical stage, glottic cancer, negative neck node and surgery only patient in supraglottis showed good treatment results in univariate analysis. The clinical stage and primary site of laryngeal cancer were found to be significant prognostic factors in laryngeal cancer patients in multivariate analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.4
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• pp.109-122
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• 1983

An accurate thick beam element (TB4) which includes the effects of the shear deformation and rotatory inertia has been degenerated from the three dimensional continuum by employing the Timoshenko beam assumptions. The proposed TB4 element has four nodes and two degrees of freedom at each node, totally eight degrees of freedom. The transverse deflection W and plane rotation ${\theta}$ with the cubic interpolation functions are selected as nodal variables. The element characteristics are formulated by discretizing the beam equations of motion, using the Galerkin weighted residual method, and are numerically integrated by the reduced shear integration technique, using the three-point Gauss quadrature with the various shear coefficients. Several numerical examples are analyzed to demonstrate the accuracy and the monotonic convergence behavior of the proposed TB4 beam element. The result indicates that the TB4 element shows the more excellent performance and the monotonic convergence behavior than the other existing Timoshenko beam type elements for the whole range of the beam aspect ratios, in both static and free vibration analyses.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.395-399
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• 2017

The LPI fuel filter housings used in automobiles were made from conventional die castings but have recently been developed by cold forging to improve the weight and durability. On the other hand, a sink may develop at the core of the forged product due to the resulting T-shape, which not only reduces the aesthetics, but also increases the post-processing cost of the product. Therefore, this research focused on methods to predict and mitigate sink development and progression during the T-shape forging process. Finite element analysis of the forging process was first performed to determine the optimal initial workpiece devoid of burrs and underfills. An accurate sink prediction was then obtained via metal flow analysis, which was a result of the finite element simulation. Through finite element analysis, it was confirmed that sink development is a product of the differences in nodal velocities arising from the T-shaped forging process. Consequently, a pad was inserted beneath the sink to minimize these velocity differences. The results yielded significant improvement with regard to the sink defect. This method was practically applied to an industrial site to validate the sink improvement.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.381-391
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• 2008

The eigenvalue technique is introduced to overcome the problem of truncation errors caused by temporal discretization of numerical analysis. The eigenvalue technique is different from simulation in that only the space is discretized. The spatially discretized equation is diagonized and the linear dynamic system is then decoupled. The time integration can be done independently and continuously for any nodal point at any time. The results of eigenvalue technique are compared with the exact solution and FEM numerical solution. The eigenvalue technique is more efficient than the FEM to the computation time and the computer storage in the same conditions. This technique is applied to the solute transport analysis in nonuniform flow fields around underground storage caverns. This method can be very useful for time consuming simulations. So, a sensitivity analysis is carried out by using this method to analyze the safety of caverns from nearly located contaminant sources. According to the simulations, the reaching time from source to the nearest cavern may takes 50 years with longitudinal dispersivity of 50 m and transversal dispersivity of 5 m, respectively.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.143-150
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• 1996

This is an explicit-Implicit, finite element analysis for linear as well as nonlinear hygrothermal stress problems. Additional features, such as moisture diffusion equation, crack element and virtual crack extension(VCE ) method for evaluating J-integral are implemented in this program. The Linear Elastic Fracture Mechanics(LEFM) Theory is employed to estimate the crack driving force under the transient condition for and existing crack. Pores in materials are assumed to be saturated with moisture in the liquid form at the room temperature, which may vaporize as the temperature increases. The vaporization effects on the crack driving force are also studied. The Ideal gas equation is employed to estimate the thermodynamic pressure due to vaporization at each time step after solving basic nodal values. A set of field equations governing the time dependent response of porous media are derived from balance laws based on the mixture theory Darcy's law Is assumed for the fluid flow through the porous media. Perzyna's viscoplastic model incorporating the Von-Mises yield criterion are implemented. The Green-Naghdi stress rate is used for the invariant of stress tensor under superposed rigid body motion. Isotropic elements are used for the spatial discretization and an iterative scheme based on the full newton-Raphson method is used for solving the nonlinear governing equations.