• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.3
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• pp.491-499
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• 2002

A p-version finite element model based on degenerate shell element is proposed tot the analysis of orthotropic laminated plates. In the nonlinear formulation of the model, the total Lagrangian formulation is adopted with large deflection and moderate rotation being accounted tot in the sense of yon Karman hypothesis. The material model is based on the Huber-Mises yield criterion and Prandtl-Reuss flow rule in accordance with the theory of strain hardening yield function, which is generalized lot anisotropic materials by introducing the parameters of anisotropy. The model is also based on extension of equivalent-single layer laminate theory(ESL theory) with shear deformation, leading to continuous shear strain at the interface of two layers. The integrals of Legendre polynomials are used for shape functions with p-level varying from 1 to 10. Gauss-Lobatto numerical quadrature is used to calculate the stresses at the nodal points instead of Gauss points. The validity of the proposed P-version finite element model is demonstrated through several comparative points of iew in terms of ultimate load, convergence characteristics, nonlinear effect, and shape of plastic tone.

• Journal of Yeungnam Medical Science
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• v.7 no.2
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• pp.197-202
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• 1990

Mechanical obstruction of the common hepatic duct includes the following causes ; choledocholithiasis, sclerosis, cholangitis, pancreatic carcinoma, cholangiocarcinoma, postoperative stricture, primary hepatic duct carcinoma, enlarged cystic duct lymph nodes, and metastatic nodal involvement of the porta hepatis. Partial mechanical obstruction of the common hepatic duct caused by impaction of stones and inflammation surrounding the vicinity of the neck of the gallbladder had been reported on the "syndrome del conducto hepatico" in 1948 by Mirizzi. Nowadays, this disease was named by Mirizzi syndrome. Mirizzi syndrome is a rare entity of common hepatic duct obstruction that results from an inflammatory response secondary to a gallstone impacted in the cystic duct or neck of the gallbladder. It results from an almost parallel course and low insertion of the cystic duct into the common hepatic duct. In a varient of Mirizzi's syndrome, the cause of the common hepatic duct obstruction was a primary cystic duct carcinoma rather than gallstone disease. A 71-year-old man was admitted with a four-day history of right upper quadrant abdominal pain. Past medical history was unremarkable. On physical examination, the patient had a temperature of $38^{\circ}C$, icteric sclera and right upper quadrant tenderness. Pertinent laboratory findings included WBC 18,000/$cm^2$;albumin 2.6g/dl(normal 3.9-5.1) ; SGOT 183u/L(normal 0-50) ; SGPT167u/L(normal 0-65) ; bilirubin, 8.2mg/dl(normal 0-1) with the direct bilirubin, 4.4mg/dl(normal 0-0.4). Ultrasonography revealed a dilated extrahepatic biliary tree. ERCP showed that the superior margin was angular and more consistent with a calculus causing partial CHD obstruction(Mirizzi syndrome). At surgery a diseased gallbladder containing calculi was found. In addition, there was two calculi partially eroding through the proximal portion of the cystic duct and compressing the common hepatic duct. A cholecystectomy and excision of common bile duct was performed, with Roux-en-Y hepaticojejunostomy. The postoperative course was uneventful.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.9
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• pp.1041-1050
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• 2011

An elasto-plastic finite element method using the theory of strain gradient plasticity is proposed to evaluate the size dependency of structural plasticity that occurs when the configuration size decreases to micron scale. For this method, we suggest a low-order plane and three-dimensional displacement-based elements, eliminating the need for a high order, many degrees of freedom, a mixed element, or super elements, which have been considered necessary in previous researches. The proposed method can be performed in the framework of nonlinear incremental analysis in which plastic strains are calculated and averaged at nodes. These strains are then interpolated and differentiated for gradient calculation. We adopted a strain-gradient-hardening constitutive equation from the Taylor dislocation model, which requires the plastic strain gradient. The developed finite elements are tested numerically on the basis of typical size-effect problems such as micro-bending, micro-torsion, and micro-voids. With respect to the strain gradient plasticity, i.e., the size effects, the results obtained by using the proposed method, which are simple in their calculation, are in good agreement with the experimental results cited in previously published papers.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.96-104
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• 2010

A comparative study was performed in gnotobiotic and greenhouse conditions to evaluate the effect of exogenous application of indole-3-acetic acid (IAA) and inoculation of Methylobacterium spp. possessing 1-aminocyclopropane-1-carboxylate deaminase (ACCD) and IAA activity on red pepperand tomato seedling growth and development. Application of 1.0 ${\mu}g\;mL^{-1}$ IAA positively influenced root growth while high concentrations (>10.0 ${\mu}g\;mL^{-1}$) suppressed root growth of red pepper and tomato under gnotobiotic condition. On the other hand, inoculation of Methylobacterium strains with ACCD activity and IAA or without IAA enhanced root growth in both plants. Similarly, under greenhouse condition the inoculation of Methylobacterium sp. with ACCD activity and IAA enhanced plant fitness recorded as average nodal length and specific leaf weight (SLW) but the effect is comparable with the application of low concentrations of IAA. Seedling length was significantly increased by Methylobacterium strains while total biomass was enhanced by Methylobacterium spp. and exogenous applications of < 10.0 ${\mu}g\;mL^{-1}$ IAA. High concentrations of IAA retard biomass accumulation in red pepper and tomato. These results confirm that bacterial strains with plant growth promoting characters such as IAA and ACCD have characteristic effects on different aspects of growth of red pepper and tomato seedlings which is comparable or better than exogenous applications of synthetic IAA.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.1
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• pp.1-8
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• 2014

Using the level set and the meshfree methods, we develop a topological shape optimization method applied to linear elasticity problems. Design gradients are computed using an efficient adjoint design sensitivity analysis(DSA) method. The boundaries are represented by an implicit moving boundary(IMB) embedded in the level set function obtainable from the "Hamilton-Jacobi type" equation with the "Up-wind scheme". Then, using the implicit function, explicit boundaries are generated to obtain the response and sensitivity of the structures. Global nodal shape function derived on a basis of the reproducing kernel(RK) method is employed to discretize the displacement field in the governing continuum equation. Thus, the material points can be located everywhere in the continuum domain, which enables to generate the explicit boundaries and leads to a precise design result. The developed method defines a Lagrangian functional for the constrained optimization. It minimizes the compliance, satisfying the constraint of allowable volume through the variations of boundary. During the optimization, the velocity to integrate the Hamilton-Jacobi equation is obtained from the optimality condition for the Lagrangian functional. Compared with the conventional shape optimization method, the developed one can easily represent the topological shape variations.

• Journal of Radiation Protection and Research
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• v.16 no.2
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• pp.41-54
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• 1991

This paper aimed to analyse dose sensitivity to the controllable parameters of indoor radon $(^{222}Rn)$ and its decay products (Rn-D) by applying the input~output linear system theory. Physical behaviors of $^{222}Rn\;&\;Rn-D$ were analyzed in terms of $(^{222}Rn)$ gas -generation, -migation and -infiltration to indoor environments, and the performance output-function, i. e. mean dose equivalent to Tracho-Bronchial (TB) lung region, was assessed to the following extented ranges of the controllable paramenters; a) the ventilation rate $constant({\lambda}_v)\;:\;0{\sim}50[h^{-l}].\;b)$ the attachment rate $constant({\lambda}_a)\;:\;0{\sim}500[h^{-l}].\;c)$ the unattached-deposition rate constant (${\lambda}^u_d)\;:\;0-50[h-l]$. A linear input-output model was reconstructed from the original models in literatures, as follows, which was modified into the matrices consisting of 111 nodal equations; a) indoor $^{222}Rn\;&\;Rn-D$ Behaviour; Jacobi-Porstendoerfer-Bruno model.

• Journal of Korea Port Economic Association
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• v.28 no.3
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• pp.235-257
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• 2012

Recently the role of ports has been changed to satisfy flexibly needs of demands in global economy. A new concept for ports is not just a place for international trade but an important nodal point in logistics chain. The changing environment like this trend creates a high degree of uncertainty and leaves port managers confused with the question how to respond effectively to dynamic market. The latest studies provide that the port must have a good hinterland to achieve competitive advantages in a logistics chain. Korean Government announced "The Master Development Plan for Port Logistics Parks in Korea" in 2006. This contains the plan of hinterland construction of Busan New Port to achieve the status of logistics hub in Asian market. Previous studies rely solely on traditional DCF(discounted cash flow) analysis for investment of hinterland. However DCF method does not include irreversibility, uncertainty and the choice of timing for investment project. This thesis introduces a ROPM(real options pricing model) which overcomes the limitations of traditional valuation methods. The option valuations in this study utilize the Black-Scholes model, the binomial model and the MonteCarlo simulation to value investment opportunity of a port hinterland. In this thesis, an attempt is made to modify the NPV criterion by incorporating the real options approach, and its application is demonstrated in a hinterland construction investment plan. This research has conducted an empirical analysis by calculating economic value of the investment for a hinterland of Busan New Port.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.1
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• pp.98-113
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• 2014

The purpose of this study is to investigate the changes in the accessibility of the Metropolitan Seoul Transit systems since 2000, in which many new subway lines have been constructed as well as other urban transit lines have been connected to the systems. We suggest an accessibility measure model for Un-fixed Transportation Networks. In order to measure the nodal accessibility based on the mobility, we apply path-distance, physical-distance, and time-distance as the distance impedance measurement. Specifically, we develop time-distance algorithms to measure the time-distance between each pairs of transit stations based on the T-card transaction databases. We apply the model to the Metropolitan Seoul Transit systems in two time points(2005 and 2011). We examine the results in terms of three distance accessibility measures. Time-distance accessibility explains better the urban land use patterns in the Metropolitan Seoul area than the other two. We visualize the spatial patterns of time-distance accessibility by applying GIS, and analyze the spatial structures of accessibility in the Metrropolitan Seoul area between two time points.

• Journal of Gastric Cancer
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• v.12 no.2
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• pp.81-87
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• 2012

Purpose: The aim of the present study was to assess the association between the pre-operative plasma fibrinogen level and the adjacent organ involvement in advanced gastric cancer. Materials and Methods: A total of 923 pre-operative plasma samples were obtained from 923 patients diagnosed clinically as having advanced gastric cancer, and fibrinogen levels were measured by immunoassay. Associations between fibrinogen levels and clinicopathologic findings (depth of tumor, adjacent organ involvement, and lymph node metastasis), along with survival were examined by univariate and multivariate analyses. Results: Tumor size, tumor depth, and the presence of lymph node metastasis were found to be positively correlated with the preoperative plasma fibrinogen levels (P<0.001). Fifty (5.4%) patients had adjacent organ involvement. Lymphatic invasion (P<0.001), tumor size (P<0.001), clinical T (depth of invasion) stage (P<0.001), and clinical nodal stage (P=0.018) were found to be associated with adjacent organ involvement. Univariate and multivariate regression analyses showed that a preoperatively elevated plasma fibrinogen level was associated with adjacent organ involvement (P<0.001, 0.028), and Kaplan-Meier analysis showed that it was associated with poorer survival (P<0.001). Conclusions: Plasma fibrinogen was found to be a clinically useful marker of adjacent organ involvement and overall survival. When a high fibrinogen level is encountered, preoperatively, adjacent organ involvement should be suspected in clinically advanced gastric cancer.

• 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.