• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.1041-1063
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• 2014

Some results on the hydroelasticity of ultra large container ships related to the beam structural model and restoring stiffness achieved within EU FP7 Project TULCS are summarized. An advanced thin-walled girder theory based on the modified Timoshenko beam theory for flexural vibrations with analogical extension to the torsional problem, is used for formulation of the beam finite element for analysis of coupled horizontal and torsional ship hull vibrations. Special attention is paid to the contribution of transverse bulkheads to the open hull stiffness, as well as to the reduced stiffness of the relatively short engine room structure. In addition two definitions of the restoring stiffness are considered: consistent one, which includes hydrostatic and gravity properties, and unified one with geometric stiffness as structural contribution via calm water stress field. Both formulations are worked out by employing the finite element concept. Complete hydroelastic response of a ULCS is performed by coupling 1D structural model and 3D hydrodynamic model as well as for 3D structural and 3D hydrodynamic model. Also, fatigue of structural elements exposed to high stress concentration is considered.

• East Asian Economic Review
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• 제25권1호
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• pp.33-71
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• 2021

Many different approaches and databases have been developed for the evaluation of non-tariff measures (NTMs) and free trade agreements (FTAs). This paper is devoted to the EU-South Korea agreement, which is the first 'second-generation' FTA of the EU, addressing a wide array of non-tariff policies. We review the evolution of NTM types applicable to the EU-South Korea trade relationship and the role of NTMs in ex-ante and ex-post analyses of the agreement. Subsequently a structural gravity model is employed to assess the value added of information on different aspects of FTAs and types of NTMs by evaluating their ability to predict the trade effects of the EU-South Korea FTA. Our results show that, when accounting for information on the components common in modern deep trade agreements, no additional trade effect is attributable to the EU-South Korea FTA. The evolution of NTMs differs considerably across indicators used, but trade predictions are hardly affected. Most specifications point towards a negative effect of bilateral differences in the number of technical barriers to trade (TBT) applied and sanitary and phytosanitary measures (SPS) against which trading partners issued complaints at the WTO.

• 인터넷정보학회논문지
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• 제25권4호
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• pp.73-86
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• 2024

With the acceleration of regional economic integration, the agricultural trade network within the RCEP region presents new opportunities and challenges for member countries. This study focuses on agricultural trade among RCEP members from 2011 to 2020, utilizing social network analysis to explore the structural characteristics and evolutionary trends of the trade network. Additionally, an extended gravity model is employed to empirically analyze the key factors influencing South Korea's agricultural trade with other member countries. The findings reveal that: (1) Agricultural trade relationships within the RCEP region are stable and mature, with high interconnectivity in the trade network, indicating a trend towards balanced development. (2) The positions of member countries within the agricultural trade network are characterized by both high density and heterogeneity. (3) South Korea's agricultural trade with RCEP member countries is positively influenced by the economic size, population size, and governance level of its trading partners, while South Korea's own indicators show no significant effect. The trade distance between South Korea and member countries also has a positive impact on agricultural trade. By combining social network analysis with an extended gravity model, this study provides a multi-faceted quantitative analysis of the RCEP agricultural trade network, offering new insights into regional agricultural trade. It also provides empirical evidence for agricultural trade cooperation between South Korea and other RCEP countries.

• Structural Monitoring and Maintenance
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• 제3권2호
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• pp.129-144
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• 2016

We present a methodology to validate with monitoring data finite element models of existing concrete dams: numerical analyses are performed to assess the structural response under the effects of seasonal loading conditions, represented by hydrostatic pressure on the upstream-downstream dam surfaces and thermal variations as recorded by a thermometers network. We show that the stiffness effect of the rock foundation and the surface degradation of concrete due to aging are crucial aspects to be accounted for a correct interpretation of the real behavior. This work summarizes some general procedures developed by this research group at Politecnico di Milano on traditional static monitoring systems and two significant case studies: a buttress gravity and an arch-gravity dam.

• East Asian Economic Review
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• 제22권3호
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• pp.275-306
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• 2018

Amid a general rise in protectionism and a trade war between the world's two largest economies, this paper analyzes changes in gains from trade for the world over a decade marked by rapid global economic integration preceding the global financial crisis of 2007-08. It employs state-of-the-art quantitative trade models based on the gravity equation to estimate autarky gains from trade, as well as a recently introduced ANOVA-type structural estimation of the gravity equation to obtain trade costs free of residual trade cost bias. Between 1995 and 2006, the cost of moving to autarky increased by about 45% on average. A decomposition exercise suggests most of the increase in autarky gains from trade on average was due to increases in import shares in total spending, with a limited role for reallocations of spending across sectors with varied trade elasticities. Changes in trade costs between 1995 and 2006 are found to have increased autarky gains from trade, as measured in 2006, by up to 100%.

• Structural Engineering and Mechanics
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• 제21권5호
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• pp.591-620
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• 2005

A general analytical model for thin-walled composite beams with an arbitrary open/(or/and) closed cross section and arbitrary laminate stacking sequence i.e., symmetric, anti-symmetric as well as un-symmetric with respect to the mid plane of the laminate, is developed in the first paper. All the mechanical properties, mechanical centre of gravity and mechanical shear centre of the cross section are defined in the function of the geometry and the material properties of the section. A program "fungen" and "clprop" are developed in Fortran to compute all the mechanical properties and tested for various isotropic sections first and compared with the available results. The locations of mechanical centre of gravity and mechanical shear centre are given with respect to the fibre angle variation in composite beams. Variations of bending and torsional stiffness are shown to vary with respect to the fibre angle orientations.

• Structural Engineering and Mechanics
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• 제86권1호
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• pp.93-107
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• 2023

In this paper, a density based topology optimization is proposed for generating of supports required in additive manufacturing to maintain the overhanging regions of main structures during layer by layer fabrication process. For this purpose, isogeometric analysis method is employed to model geometry and structural analysis of main and support structures. In order to model the problem two cases are investigated. In the first case, design domain of supports can easily be separated from the main structure by using distinct isogeometric patches. The second case happens when the main structure itself is optimized by using topology optimization and the supports should be designed in the voids of optimum layout. In this case, in order to avoid boundary identification and re-meshing process for separating design domain of supports from main structure, a parameterization technique is proposed to identify the design domain of supports. To achieve this, two density functions are defined over the entire domain to describe the main structure and supporting areas. On the other hand, since supports are under gravity loads while main structure and its stiffness is not completed during manufacturing process, in the proposed method, stiffness of the main structure is considered to be trivial and the gravity loads are also naturally applied to design support structures. By doing so, the results show reasonable supports are created to protect, continuously, overhanging surfaces of the main structure. Several examples are presented to demonstrate the efficiency of the proposed method and compare the results with literature.

• 자원환경지질
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• 제30권4호
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• pp.363-369
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• 1997

As a part of the study to know the deep geological structure of the Ogcheon Zone. gravity survey is performed along the survey line of which direction is roughly perpendicular to major faults of the Zone. Recent studies for petrology. geochemistry. and structural geology in south-western Ogcheon Zone are outlined. Raw gravity data are corrected to obtain Bouguer anomalies and the anomalies are interpreted to obtain subsurface structures along the survey line. The subterranean density discontinuities determined from the power spectrum method are appeared at depths of 15.4 km and 2.8 km. It is considered that the depth of 15.4 km indicates the boundary between upper and lower crust. Probably the depth of 2.8 km represents the boundary between upper volcanic formations and granites. Alternatively. the observed Bouguer anomalies are interpreted in terms of lateral density variation model. Finally. the subterranean geological structure to satisfy the Bouguer anomalies is presented through the iterative forward method in which results obtained from surface geological informations and from the inverse method are adopted as an initial model.

• 한국유체기계학회 논문집
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• 제15권1호
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• pp.46-51
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• 2012

This study is to confirm the deformation of blade when the location of stacking is moving. Also, it desire to determine the most stable location of stacking from the analysis. In the previous study, it is Known that moving the location of stacking is not influence to the aerodynamic performance. In this study SolidWorks premium 2010 SP4 is used for structure analysis. In reference blade and other 3 model analysis, the two mesh type is used, one is standard mesh type in SolidWorks, the other is curvature-based mesh type. The result of curvature-based mesh type is more stable than one of the standard mesh type regardless of mesh size, the number of mesh. The deformation of blade tip is the smallest, when the location of stacking is identical to the center of gravity of the blade section profile. So, if possible is design, this study recommends that the location of stacking is identical to the center of gravity the blade.

• 한국전산구조공학회논문집
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• 제23권5호
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• pp.501-507
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• 2010

본 논문에서는 중력하중 및 풍하중, 지진하중을 받는 지상 8층, 지하 3층의 RC(Reinforced Concrete) 빌딩 시공에 필요한 부재의 재료비를 줄이기 위해 중량을 감소시키는 구조 최적설계를 수행한다. 이를 위해 설계요구사항을 바탕으로 부재의 부피를 최소화하는 설계변수값을 찾기 위한 설계문제를 정식화한다. 최적설계 수행을 위해 상용 PIDO(Process Integration and Design Optimization) 툴인 PIAnO(Process Integration, Automation and Optimization)에서 제공하는 다양한 설계기법들을 이용한다. 먼저 실험계획법(Design of Experiments; DOE)을 이용하여 실험계획을 세우고, 실험점에 따라 건축분야 범용 구조해석 프로그램인 MIDAS Gen을 사용하여 구조해석을 수행한다. 그리고 해석결과를 바탕으로 각 응답에 대한 근사모델을 생성한 후 근사모델의 예측성능을 평가한다. 예측성능이 검증된 근사모델과 최적화기법을 이용하여 최적설계를 수행하고, 설계조건을 만족하면서 부재의 부피를 최소화하는 최적 설계변수값을 도출함으로서 본 논문에서 제안된 설계방법의 유효성을 보이고자 한다.