• 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.

• 지식경영연구
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• 제11권5호
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• pp.1-23
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• 2010

In order to provide a better understanding about the phenomenon of KM assimilation, this study attempts to conceptually develop and empirically compare two different models: (1) the first model, which considers the KM process as the flow of knowledge that plays an intervening role between knowledge stocks (i.e., knowledge worker, technical knowledge infrastructure, external knowledge linkage, knowledge strategy, and internal knowledge climate) and the level of KM assimilation; and (2) the second model is a simple direct effect formulation without any distinction between knowledge stock and flow. These two models were then tested and compared using the responses of 187 Korean organizations that had already implemented enterprise-wide KM systems. The findings indicate that the two models are useful in explaining successful KM assimilation. However, the first causal model with the distinction between knowledge stock and flow assesses the effectiveness of KM more accurately than the second model without the distinction. Interestingly, the KM process was shown to be the most critical factor for the proliferation of KM activities across an organization. The findings of this study are expected to serve not only as early groundwork for researchers hoping to understand KM and its effective assimilation in organizations, but should also provide practitioners with guidelines as to how they can enhance their KM assimilation level so as to improve their organizational performance.

• 한국정보시스템학회지:정보시스템연구
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• 제26권4호
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• pp.189-202
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• 2017

Purpose The purpose of this study is to find the factors for explaining the relationship between the satisfaction of IT consulting and entrepreneurship based on the corporate performance, financial and economic performance. Design/methodology/approach This study made a design of the research model by integrating the factors of entrepreneurship and satisfaction of IT consulting on the basis of ecosystem. In addition, this study, did empirical analysis of the structural equation model by PLS(Partial Least Squares) in order to find out the moderating effect of satisfaction of IT consulting on entrepreneurship. Findings According to the empirical analysis result, this study confirmed that the moderating effect of satisfaction of IT consulting on entrepreneurship, which increase the influence the effect of entrepreneurship on the corporate performance. However, the second order factor of enterprise ecosystem has no effect on the corporate performance. In addition, this study find out that the important role of IT consulting according to the change of business environment.

• Earthquakes and Structures
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• 제11권6호
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• pp.943-966
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• 2016

Recently, magnetorheological elastomer (MRE) material and its devices have been developed and attracted a good deal of attention for their potentials in vibration control. Among them, a highly adaptive base isolator based on MRE was designed, fabricated and tested for real-time adaptive control of base isolated structures against a suite of earthquakes. To perfectly take advantage of this new device, an accurate and robust model should be built to characterize its nonlinearity and hysteresis for its application in structural control. This paper first proposes a novel hysteresis model, in which a nonlinear hyperbolic sine function spring is used to portray the strain stiffening phenomenon and a Voigt component is incorporated in parallel to describe the solid-material behaviours. Then the fruit fly optimization algorithm (FFOA) is employed for model parameter identification using testing data of shear force, displacement and velocity obtained from different loading conditions. The relationships between model parameters and applied current are also explored to obtain a current-dependent generalized model for the control application. Based on the proposed model of MRE base isolator, a second-order sliding mode controller is designed and applied to the device to provide a real-time feedback control of smart structures. The performance of the proposed technique is evaluated in simulation through utilizing a three-storey benchmark building model under four benchmark earthquake excitations. The results verify the effectiveness of the proposed current-dependent model and corresponding controller for semi-active control of MRE base isolator incorporated smart structures.

• Earthquakes and Structures
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• 제7권2호
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• pp.217-231
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• 2014

Ancient masonry towers are regarded as among the most important historical heritage structures of the world. These slender structures typically have orthogonal and circular geometry in plane. These structural forms are commonly installed with adjacent structures. Because of their geometrical shapes and structural constraints, ancient masonry towers are more vulnerable to earthquake damage. The main goal of the paper is to investigate the seismic behavior of Erzurum Clock Tower under earthquake loading and to determine the contribution of the castle walls to the seismic performance of the tower. In this study, four three-dimensional finite element models of the Erzurum Clock Tower were developed and the seismic responses of the models were investigated. Time history analyses were performed using the earthquakes that took place in Turkey in 1983 near Erzurum and in 1992 near Erzincan. In the first model, the clock tower was modeled without the adjacent walls; in the second model, the clock tower was modeled with a castle wall on the south side; in the third model, the clock tower was modeled with a castle wall on the north side; and in the last model, the clock tower was modeled with two castle walls on both the north and south sides. Results of the analyses show that the adjacent walls do not allow lateral movements and the horizontal displacements decreases. It is concluded that the adjacent structures should be taken into consideration when modeling seismic performance in order to get accurate and realistic results.

• Structural Engineering and Mechanics
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• 제8권6호
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• pp.607-622
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• 1999

Being a significant mode of deformation, shear effect in addition to the other modes of stretching and bending have been considered to develop two finite element models for the analysis of beams on elastic foundation. The first beam model is developed utilizing the differential-equation approach; in which the complex variables obtained from the solution of the differential equations are used as interpolation functions for the displacement field in this beam element. A single element is sufficient to exactly represent a continuous part of a beam on Winkler foundation for cases involving end-loadings, thus providing a benchmark solution to validate the other model developed. The second beam model is developed utilizing the hybrid-mixed formulation, i.e., Hellinger-Reissner variational principle; in which both displacement and stress fields for the beam as well as the foundation are approxmated separately in order to eliminate the well-known phenomenon of shear locking, as well as the newly-identified problem of "foundation-locking" that can arise in cases involving foundations with extreme rigidities. This latter model is versatile and indented for utilization in general applications; i.e., for thin-thick beams, general loadings, and a wide variation of the underlying foundation rigidity with respect to beam stiffness. A set of numerical examples are given to demonstrate and assess the performance of the developed beam models in practical applications involving shear deformation effect.

• 한국정보시스템학회지:정보시스템연구
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• 제28권2호
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• pp.73-92
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• 2019

Purpose This study conducted an empirical study on the influence of institutional mechanisms on the formation of customer trust among leading online businesses. This study focused on the construct of PEEIM(Perceived Effectiveness of e-Commerce Institutional Mechanisms) which is the perceived recognition of institutional mechanisms for e-Commerce in general and the construct of PEIS which is the perceived recognition of institutional mechanisms that are implemented by vendors. Design/methodology/approach The online and offline surveys were conducted for the leading online shopping vendors in Korea and 292 data were used for the empirical analysis. The research model was tested using partial least squares structural equation modeling (PLS-SEM) in this study. The full measurement model including the formative second-order constructs was examined with the exploratory factor analysis. The structural model was analyzed via a two-stage approach. To analyze the research model this study used Smart PLS 2.0 program. Findings The findings showed that PEEIM negatively moderates the relationship between satisfaction in vender and trust in vender, but had no moderating effect between trust in vender and repurchase intention. In addition, the institutional mechanisms of vendors(PEIS) have been shown to have a direct impact on the vender's trust.

• 호스피스학술지
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• 제2권1호
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• pp.1-20
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• 2002

The purpose of this study is to develop a management model to effectively provide hospice service of nursing home. In a method of study to achieve this purpose, a positive research and literature study have been performed at the same time. Concerning contents to be examined as a definition of notions and patterns about hospice for the aged, foreign hospice and structural elements of hospice management, a literature study to support a theoretical background has presented leading studies as an analysis form of this study through analyzing domestic and foreign literature, thesis, journal and so on. In order to attain the purpose of this study, the positive research is to carry out a survey of demand and desire of people who have already got hospice service in the first place as a fact-finding survey related to the subject of hospice service, investigate organizations to operate nursing home and hospice and relevant experts in the second place as a survey of supply system to provide hospice service, and develop an appropriate management model to connect the demand and supply of nursing home through it. Therefore, this study has developed a delivery system and a chart of the practical trend to be done minutely, presenting a model to manage a hospice of nursing home based on the above results. The management model externally has connected medical team of hospital with hospice team of home based on a community, and internally is composed centering on five elements such as administrative organization, manpower, program and contents of service, finances. In practical model of hospice management of nursing home, in order to plan a program, provide service and give a high-quality service to the aged, this study has presented a trend chart of service management on the basis of five structural elements, an analysis form of this study. In conclusion, this study could present data to develop a hospice in the field of nursing home for the aged by showing a model concerning a hospice management of nursing home, but in my opinion, a following study to be detailed and developed even more than this study should be continued.

• Wind and Structures
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• 제15권3호
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• pp.189-208
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• 2012

Lock-in and drag amplification phenomena are studied for a flexible cantilever using a simplified fluid-structure interaction approach. Instead of solving the 3D domain, a simplified setup is devised, in which 2D flow problems are solved on a number of planes parallel to the wind direction and transversal to the structure. On such planes, the incompressible Navier-Stokes equations are solved to estimate the fluid action at different positions of the line-like structure. The fluid flow on each plane is coupled with the structural deformation at the corresponding position, affecting the dynamic behaviour of the system. An Arbitrary Lagrangian-Eulerian (ALE) approach is used to take in account the deformation of the domain, and a fractional-step scheme is used to solve the fluid field. The stabilization of incompressibility and convection is achieved through orthogonal quasi-static subscales, an approach that is believed to provide a first step towards turbulence modelling. In order to model the structural problem, a special one-dimensional element for thin walled cross-section beam is implemented. The standard second-order Bossak method is used for the time integration of the structural problem.

• 국제학술발표논문집
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• The 8th International Conference on Construction Engineering and Project Management
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• pp.3-12
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• 2020

Nowadays, as-is BIM generation has been popularly adopted in the architecture, engineering, construction and facility management (AEC/FM) industries. In order to generate a 3D as-is BIM of a structural component, current methods require a registration process that merges different sets of point cloud data obtained from multiple locations, which is time-consuming and registration error-prone. To tackle this limitation, this study proposes a registration-free 3D point cloud data acquisition technique for as-is BIM generation. In this study, small-size mirrors that rotate in both horizontal and vertical direction are used to enable the registration-free data acquisition technique. First, a geometric model that defines the relationship among the mirrors, the laser scanner and the target component is developed. Second, determinations of optimal laser scanner location and mirror location are performed based on the developed geometrical model. To validate the proposed registration-free as-is BIM generation technique, simulation tests are conducted on key construction components including a PC slab and a structural wall. The result demonstrates that the registration-free point cloud data acquisition technique can be applicable in various construction elements including PC elements and structural components for as-is BIM generation.