• Coupled systems mechanics
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• 제4권4호
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• pp.337-364
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• 2015

In this paper we present methodology for parameters identification of constitutive model which is able to present behavior of a connection between two members in a structure. Such a constitutive model for frame connections can be cast in the most general form of the Timoshenko beam, which can present three failure modes. The first failure mode pertains to the bending in connection, which is defined as coupled plasticity-damage model with nonlinear softening. The second failure mode is seeking to capture the shearing of connection, which is defined as plasticity with linear hardening and nonlinear softening. The third failure mode pertains to the diffuse failure in the members; excluding it leads to linear elastic constitutive law. Theoretical formulation of this Timoshenko beam model and its finite element implementation are presented in the second section. The parameter identification procedure that will allow us to define eighteen unknown parameters is given in Section 3. The proposed methodology splits identification in three phases, with all details presented in Section 4 through three different examples. We also present the real experimental results. The conclusions are stated in the last section of the paper.

• 원예과학기술지
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• 제31권2호
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• pp.165-172
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• 2013

This study was conducted to investigate the effect of bulblet size on growth and bulb enlargement of Lilium Oriental hybrids, such as 'Sorbonne', 'Siberia', and 'Casa Blanca', grown in areas of high altitude (780 m), in 2009. The bulblets were oriented from tissue culture and planted to produce virus-free bulblets. All the three cultivars showed high vitality, with more than 93% producing shoots, even from small bulblets with a bulb circumference (BC) of less than 6 cm. Bulblets with BC 9-10 cm showed an increased height and number of leaves rapidly to induce the phase conversation from vegetative growth to reproductive growth. The bulblets of BC 9-10 cm in 'Sorbonne', 'Siberia', and 'Casa Blanca' had 2.0, 2.9, and 2.8 flower bud sets per plant, respectively. However, the flowers from those bulblets were not adequate as standard bulbs to produce cut-flowers for the domestic market. The larger bulblets showed more prosperous characteristics in growth and development of Lilium Oriental hybrids. Small bulblets had a high occurrence of viruses and leaf blight symptoms during cultivation, indicating the aggravated disease symptoms in the previously infected bulbs. 'Sorbonne' cultivars showed a high rate of enlargement of bulbs, and small bulblets under BC 6 cm produced more than 23% of the standard bulbs of BC 14-16 cm, which could produce cut-flowers for export. However, 'Casa Blanca' bulblets with BC 6-9 cm produced low bulbs of BC 14-16 cm at 21% level. 'Casa Blanca' cultivars had more bulb roots, longer root lengths, and higher weights than 'Sorbonne' and 'Siberia' cultivars. 'Casa Blanca' cultivars with BC over 9-10 cm grew rapidly and produced a high quantity of bulbs. In these results, 'Sorbonne' bulblets of BC 9-10, 'Siberia' bulblets of BC 10-12 cm, and 'Casa Blanca' bulblets of BC 10-12 cm produced 89%, 86%, and 93% of the standard bulbs of BC 14-16 cm, respectively. It is recommended that bulblets larger than the above sizes be used to produce cut-flowers for the export market. Experiment results suggest that production of bulbs larger than BC 18 cm requires bulblets that are larger than BC 12-14 cm of the three cultivars for the highest quality cut-flowers.

• 복식문화학회:학술대회논문집
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• 복식문화학회 2006년도 Seoul The Costume Culture Association & Ars Textrina Joint International Conference
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• pp.77-80
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• 2006

• Coupled systems mechanics
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• 제7권1호
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• pp.5-25
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• 2018

A fully-coupled thermodynamic-based transient finite element formulation is proposed in this article for electric, magnetic, thermal and mechanic fields interactions limited to the linear case. The governing equations are obtained from conservation principles for both electric and magnetic flux, momentum and energy. A full-interaction among different fields is defined through Helmholtz free-energy potential, which provides that the constitutive equations for corresponding dual variables can be derived consistently. Although the behavior of the material is linear, the coupled interactions with the other fields are not considered limited to the linear case. The implementation is carried out in a research version of the research computer code FEAP by using 8-node isoparametric 3D solid elements. A range of numerical examples are run with the proposed element, from the relatively simple cases of piezoelectric, piezomagnetic, thermoelastic to more complicated combined coupled cases such as piezo-pyro-electric, or piezo-electro-magnetic. In this paper, some of those interactions are illustrated and discussed for a simple geometry.

• Coupled systems mechanics
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• 제7권2호
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• pp.163-176
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• 2018

The ship hydrodynamics in static and dynamic states were investigated using 3-dimensional numerical simulations. The static case simulated a fixed ship, while the dynamic case considered a ship with free sinkage and trim using the mesh morphing technique. High speed was found to increase the wave elevation around the ship. Compared with the static case, the dynamic case seemed to generate higher waves near the bow and after the stern. The frictional resistance was found be to more dominant. However, the pressure resistance became gradually important with the increase of the ship speed. The trim and sinkage were also analyzed to characterize the ship hydrodynamics in the dynamic state.

• Coupled systems mechanics
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• 제4권2호
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• pp.137-155
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• 2015

This paper presents a simple procedure to obtain a substitute, homogenized mechanical response of single layer graphene sheet. The procedure is based on the judicious combination of molecular mechanics simulation results and homogenization method. Moreover, a series of virtual experiments are performed on the representative graphene lattice. Following these results, the constitutive model development is based on the well-established continuum mechanics framework, that is, the non-linear membrane theory which includes the hyperelastic model in terms of principal stretches. A proof-of-concept and performance is shown on a simple model problem where the hyperelastic strain energy density function is chosen in polynomial form.

• Coupled systems mechanics
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• 제7권6호
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• pp.669-690
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• 2018

This paper deals with numerical modeling of dynamic failure phenomena in rate-sensitive brittle and/or ductile materials. To this end, a two-dimensional continuum viscodamage-embedded discontinuity model, which is based on our previous work (see Do et al. 2017), is developed. More specifically, the pre-peak nonlinear and rate-sensitive hardening response of the material behavior, representing the fracture-process zone creation, is described by a rate-dependent continuum damage model. Meanwhile, an embedded displacement discontinuity model is used to formulate the post-peak response, involving the macro-crack creation accompanied by exponential softening. The numerical implementation in the context of the finite element method exploiting the second-order mid-point scheme is discussed in detail. In order to show the performance of the model several numerical examples are included.

• Coupled systems mechanics
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• 제13권1호
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• pp.73-93
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• 2024

In this work, we propose combining an advanced optimal control algorithm with a geometrically exact beam model. For simplicity, the 2D Reissner beam model is chosen to represent large displacements and rotations. The difficulty pertains to the nonlinear nature of beam kinematics affecting the tangent stiffness matrix, making it non-constant, which compromises direct use of optimal control methods for linear problems. Thus, we seek to accommodate a time varying control using linear-quadratic regulator (LQR) algorithm with the proposed geometrically nonlinear beam model. We provide a detailed theoretical formulation and its numerical implementation in a variational format form. Several illustrative numerical examples are provided to confirm an excellent performance of the proposed methodology.

• Journal of Periodontal and Implant Science
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• 제46권6호
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• pp.362-371
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• 2016

Purpose: The increasing demand for esthetically pleasing results has contributed to the use of ceramics for dental implant abutments. The aim of this study was to compare the biological response of epithelial tissue cultivated on lithium disilicate ($LS_2$) and zirconium oxide ($ZrO_2$) ceramics. Understanding the relevant physicochemical and mechanical properties of these ceramics will help identify the optimal material for facilitating gingival wound closure. Methods: Both biomaterials were prepared with 2 different surface treatments: raw and polished. Their physicochemical characteristics were analyzed by contact angle measurements, scanning white-light interferometry, and scanning electron microscopy. An organotypic culture was then performed using a chicken epithelium model to simulate peri-implant soft tissue. We measured the contact angle, hydrophobicity, and roughness of the materials as well as the tissue behavior at their surfaces (cell migration and cell adhesion). Results: The best cell migration was observed on $ZrO_2$ ceramic. Cell adhesion was also drastically lower on the polished $ZrO_2$ ceramic than on both the raw and polished $LS_2$. Evaluating various surface topographies of $LS_2$ showed that increasing surface roughness improved cell adhesion, leading to an increase of up to 13%. Conclusions: Our results demonstrate that a biomaterial, here $LS_2$, can be modified using simple surface changes in order to finely modulate soft tissue adhesion. Strong adhesion at the abutment associated with weak migration assists in gingival wound healing. On the same material, polishing can reduce cell adhesion without drastically modifying cell migration. A comparison of $LS_2$ and $ZrO_2$ ceramic showed that $LS_2$ was more conducive to creating varying tissue reactions. Our results can help dental surgeons to choose, especially for esthetic implant abutments, the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical dental applications.

• 화훼연구
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• 제16권2호
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• pp.118-123
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• 2008

진한 붉은색을 띤 'Tiny Ghost'를 교배모본으로 Oriental group, Longiflorum group 및 Martagon group을 부본으로 하여 효율적인 종간잡종 생산과 상품성 있는 신품종을 획득하고자 실험을 수행하였다. 개화당일 채취한 화분의 발아율은 Oriental hybrid인 'Sorbonne'이 64%로 가장 높았다. 주두수분법과 화주 절단수분법을 이용하여 수분한 결과, 'Aktiva'를 부본으로 사용한 경우를 제외하고 모두 주두수분법을 사용한 교배에서 자방이 생성되었다. 또한 Longiflorum group인 'Norina'와 'Gelria' 중 화분발아율이 높은 'Norina' 가 모두 수정에 실패하여 같은 group 내에서도 종간의 유전적 친화성에 따라 수정률이 달랐다. 'Aktiva'를 부본으로 한 교배에서 1개의 embryo sac을 적출하여 1개의 구를 생성하였으며, 'Sorbonne'을 부본으로 한 교배에서는 4개의 ovule을 치상하여 1개의 구를 얻었다. 'Gelria'를 부본으로 한 교배에서는 1개의 자방에서 embryo 5개, embryo sac 15개, ovule 7개를 얻었으며 그 중 18개체가 발아하여 66.7%의 발아율을 나타내었다. Martagon group인 L. hansonii를 부본으로 한 교배에서는 5개의 ovule을 얻어 그 중 40%가 발아하였다.