• 한국전산구조공학회논문집
• /
• 제20권2호
• /
• pp.95-103
• /
• 2007

본 논문에서는 포화된 다공성매체에서 파동의 전파속도와 감쇠를 구할 수 있는 해석적 이론해를 유도하여 제시하였다. 이론해의 유도를 위하여 압축성의 고체입자와 간극수를 고려하는 완전 연계 Field모델을 사용하였다. 완전 포화된 다공성 매체의 해석을 위한 공학적인 접근방법이 채택되었으며, 균질 영역에서 1차원 파동의 전파를 위한 이론해가 유도되었다. 본 논문에서 유도한 이론해는 고체입자의 압축성, 간극수의 압축성, 다공성입자의 변형, 공간의 감쇠(Spatial damping) 등을 고려할 수 있어 매우 다양하게 사용될 수 있다. 또한 다양한 지반체에서 두 가지 종류의 파속(Wavespeed)과 감쇠계수를 계산하는데 이용 가능하다. 본 논문에서 제시한 이론해를 전산코드화하여 파동의 전파속도와 감쇠에 대한 파라미터연구를 수행한 결과는 본 연구의 II부에 제시할 예정이다.

• Structural Engineering and Mechanics
• /
• 제75권5호
• /
• pp.571-583
• /
• 2020

Permeation grouting is of great significance for consolidating geo-materials without disturbing the original geo-structure. To dip into the filtration-induced pressure increment that dominates the grout penetration in permeation grouting, nonlinear filtration coefficients embedded in a convection-filtration model were proposed, in which the volume of cement particles in grout and the deposited particles of skeleton were considered. An experiment was designed to determine the filtration coefficients and verify the model. The filtration coefficients deduced from experimental data were used in simulation, and the modelling results matched well with the experimental ones. The pressure drop revealed in experiments and captured in modelling demonstrated that the surge of inflow pressure lagged behind the stoppage of flow channels. In addition, both the consideration of the particles loss in liquid grout and the number of filtrated particles on pore walls presented an ideal trend in filtration rate, in which the filtration rate first rose rapidly and then reached to a steady plateau. Finally, this observed pressure drop was extended to the grouting design which alters the water to cement (W/C) ratio so as to alleviate the filtration effect. This study offers a novel insight into the filtration behaviour and has a practical meaning to extend penetration distance.

• 한국지능시스템학회논문지
• /
• 제21권6호
• /
• pp.718-723
• /
• 2011

본 논문에서는 비젼 카메라를 이용한 비주얼 멀티 터치 입력 장치를 제안한다. 제안된 입력 장치는 비젼 카메라를 이용하므로 기존 스마트 폰에서 사용하는 터치 스크린 입력 장치에 비해 non-touch로 명령을 입력할 수 있다는 장점이 있다. 또한, 제안된 장치는 컴퓨터 계산 시간이 짧아 실시간 구현이 가능하고, 카메라외에 다른 장치가 필요 없으므로 존재하는 입력장치보다 싸다는 장점이 있다. 이를 위해, 먼저, HSV 컬러 모델과 라벨링 방법을 이용한 영상 처리 알고리즘을 제안한다. 그 다음, 손이 움직이는 영역의 정확성을 개선하기위해, 기하학적인 특징점, 동심원, 칼만 필터에 기본한 움직임 인식 알고리즘을 제안한다. 마지막으로, 제안된 장치는 비디오 게임, 스마트 TV, 컴퓨터등을 원격으로 제어할 수 있음을 실험을 통해 보인다.

• 대한두개안면성형외과학회지
• /
• 제12권2호
• /
• pp.86-92
• /
• 2011

Purpose: The purpose of this study was to investigate the possibility that a dynamic facial composite flap with sensory and motor nerves could be made available from donor facial composite tissue. Methods: The faces of 3 human cadavers were dissected. The authors studied the donor faces to assess which facial composite model would be most practicable. A "panorama facial flap" was excised from each facial skeleton with circumferential incision of the oral mucosa, lower conjunctiva and endonasal mucosa. In addition, the authors measured the available length of the arterial and venous pedicles, and the sensory nerves. In the recipient, the authors evaluated the time required to anastomose the vessels and nerve coaptations, anchor stitches for donor flaps, and skin stitches for closure. Results: In the panorama facial flap, the available anastomosing vessels were the facial artery and vein. The sensory nerves that required anastomoses were the infraorbital nerve and inferior alveolar nerve. The motor nerve requiring anstomoses was the facial nerve. The vascular pedicle of the panorama facial flap is the facial artery and vein. The longest length was 78 mm and 48 mm respectively. Sensation of the donor facial composite is supplied by the infraorbital nerve and inferior alveolar nerve. Motion of the facial composite is supplied by the facial nerve. Some branches of the facial nerve can be anastomosed, if necessary. Conclusion: The most practical facial composite flap would be a mid and lower face flap, and we proposed a panorama facial flap that is designed to incorporate the mid and lower facial skin with and the unique tissue of the lip. The panorama facial composite flap could be considered as one of the practicable basic models for facial allotransplantation.

• Nuclear Engineering and Technology
• /
• 제53권9호
• /
• pp.2937-2952
• /
• 2021

A typical three-dimensional finite element model for a fuel assembly is established, which is composed of 16 monolithic U-10Mo fuel plates and Al alloy frame. The distribution and evolution results of temperature, displacement and stresses/strains in all the parts are numerically obtained and analyzed with a self-developed code of FUELTM. The simulation results indicate that (1) the out-of-plane displacements of Al alloy side plates are mainly attributed to the bending deformations; (2) enhanced out-of-plane displacements appear in fuel plates adjacent to the outside Al plates, which results from the occurred bending deformations due to the applied constraints of outside Al plates; (3) an intense interaction of fuel foil with the cladding occurs near the foil edge, which appears more heavily in the fuel plates adjacent to the outside Al plates. The maximum first principal stresses in the fuel foil are similar for all the fuel plates and appear near the fuel foil edge; while, the through-thickness creep strains of fuel foil in the fuel plate near the central region of fuel assembly are larger, and the induced creep damage might weaken the fuel skeleton strength and raise the fuel failure risk.

• Steel and Composite Structures
• /
• 제43권1호
• /
• pp.91-106
• /
• 2022

This paper has focused on presenting a three dimensional theory of elasticity for free vibration of 3D-graphene foam reinforced polymer matrix composites (GrF-PMC) cylindrical panels resting on two-parameter elastic foundations. The elastic foundation is considered as a Pasternak model with adding a Shear layer to the Winkler model. The porous graphene foams possessing 3D scaffold structures have been introduced into polymers for enhancing the overall stiffness of the composite structure. Also, 3D graphene foams can distribute uniformly or non-uniformly in the shell thickness direction. The effective Young's modulus, mass density and Poisson's ratio are predicted by the rule of mixture. Three complicated equations of motion for the panel under consideration are semi-analytically solved by using 2-D differential quadrature method. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. Because of using two-dimensional generalized differential quadrature method, the present approach makes possible vibration analysis of cylindrical panels with two opposite axial edges simply supported and arbitrary boundary at the curved edges. It is explicated that 3D-GrF skeleton type and weight fraction can significantly affect the vibrational characteristics of GrF-PMC panel resting on two-parameter elastic foundations.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제17권2호
• /
• pp.391-411
• /
• 2023

Aggregates play the skeleton and supporting role in the construction field, high-precision measurement and high-efficiency analysis of aggregates are frequently employed to evaluate the project quality. Aiming at the unbalanced operation time and segmentation accuracy for multi-class segmentation algorithms of aggregate images, a Chaotic Sparrow Search Algorithm (CSSA) is put forward to optimize it. In this algorithm, the chaotic map is combined with the sinusoidal dynamic weight and the elite mutation strategies; and it is firstly proposed to promote the SSA's optimization accuracy and stability without reducing the SSA's speed. The CSSA is utilized to optimize the popular multi-class segmentation algorithm-Multiple Entropy Thresholding (MET). By taking three METs as objective functions, i.e., Kapur Entropy, Minimum-cross Entropy and Renyi Entropy, the CSSA is implemented to quickly and automatically calculate the extreme value of the function and get the corresponding correct thresholds. The image adaptive multi-class segmentation model is called CSSA-MET. In order to comprehensively evaluate it, a new parameter I based on the segmentation accuracy and processing speed is constructed. The results reveal that the CSSA outperforms the other seven methods of optimization performance, as well as the quality evaluation of aggregate images segmented by the CSSA-MET, and the speed and accuracy are balanced. In particular, the highest I value can be obtained when the CSSA is applied to optimize the Renyi Entropy, which indicates that this combination is more suitable for segmenting the aggregate images.

• Steel and Composite Structures
• /
• 제49권4호
• /
• pp.441-456
• /
• 2023

Aiming at the development trend of light weight and high strength of engineering structures, this paper experimentally investigated the seismic performance of circular-in-square high-strength concrete-filled double skin steel tubular (HCFDST) stub columns with out-of-code width-to-thickness (B/t) ratios. Typical failure mode of HCFDST stub columns appeared with the infill material crushing, steel fracture and local buckling of outer tubes as well as the inner buckling of inner tubes. Subsequently, the detailed analysis on hysteretic curves, skeleton curves and ductility, energy dissipation, stiffness degradation and lateral force reduction was conducted to reflect the influences of hollow ratios, axial compression ratios and infill types, e.g., increasing hollow ratio from 0.54 to 0.68 and 0.82 made a slight effect on bearing capacity compared to the ductility coefficients; the higher axial compression ratio (e.g., 0.3 versus 0.1) significantly reduced the average bearing capacity and ductility; the HCFDST column SCFST-6 filled with concrete obviously displayed the larger initial secant stiffness with a percentage 34.20% than the column SCFST-2 using engineered cementitious composite (ECC); increasing hollow ratios, axial compression ratios could accelerate the drop speed of stiffness degradation. The out-of-code HCFDST stub columns with reasonable design could behave favorable hysteretic performance. A theoretical model considering the tensile strength effect of ECC was thereafter established and verified to predict the moment-resisting capacity of HCFDST columns using ECC. The reported research on circular-in-square HCFDST stub columns can provide significant references to the structural application and design.

• Structural Engineering and Mechanics
• /
• 제91권5호
• /
• pp.487-502
• /
• 2024

This study introduces a novel 'multi-mushroom' structural system designed to improve seismic performance in lowrise buildings. Traditional low-rise structures tend to favor sliding over rocking due to their smaller aspect ratios despite the rocking system's superior seismic response reduction. Rocking designs allow structures to pivot at their base during seismic events, reducing damage by dissipating energy. The proposed multi-mushroom system divides the building into four equal sections with small gaps in between, each capable of independent rocking. Numerical analyses are conducted using scaled earthquake records from far- and near-source events to evaluate this system's performance. The results indicated that the multimushroom system significantly reduces plastic hinge formation compared to conventional designs. The system also demonstrated enhanced beam performance and a robust base girder, contributing to reduced collapse vulnerability. The 3-story model exhibited the most favorable behavior, effectively mitigating peak roof drift values, where the rocking system achieved a 21% reduction in mean roof displacement for near-field records and 15% for far-field records. However, the 5-story configuration showed increased roof displacement, and the 7-story model recorded higher incidences of collapse prevention (CP) hinges, indicating areas for further optimization. Overall, the multi-mushroom system enhances seismic resilience by minimizing plastic hinge formation and improving structural integrity. While the system shows significant promise for low-rise buildings, challenges related to roof displacement and inter-story drift ratio in taller structures necessitate further research. These findings suggest that the multi-mushroom system offers a viable solution for seismic risk reduction, contributing to safer and more sustainable urban development in earthquake-prone areas.

• 정보처리학회논문지:소프트웨어 및 데이터공학
• /
• 제2권7호
• /
• pp.479-486
• /
• 2013

정보 시스템의 골격이라고도 할 수 있는 데이터 모델은 프로세스 모델과 함께 정보 시스템에 있어서 중요한 두개의 축을 이룬다. 데이터 모델의 핵심요소로는 엔터티, 속성, 관계가 있으며, 이 중에서도 엔터티는 데이터 모델에서 가장 근본적인 요소로서, 엔터티를 명확하게 도출하지 못한다면 데이터 모델 전체가 모호해지게 된다. 본 연구에서는 엔터티 도출에 대해서만 다루었다. 기존의 엔터티를 도출하는 방법은 설계자의 경험과 업무지식에 많이 의존되고 명확한 절차가 제시되지 않아, 초보자나 미숙련자가 접근하기에는 많은 어려움이 있다. 이를 해결하는데 도움이 될 수 있도록 본 연구에서는 선행연구의 제안 절차를 통해 미리 도출된 대상업무에서 체계적인 절차로 엔터티를 도출할 수 있는 업무기반 엔터티 도출 절차를 제안한다. 그리고 데이터 모델링에 경험이 없는 학부생들을 대상으로 가상업무에 대하여 제안 절차를 적용하도록 하였고, 기존 방법과 제안 절차의 비교가 불가능하다는 점을 감안하여 학생들이 도출한 엔터티와 모범 답안 간의 유사도 검사로 제안 절차를 검증하였다. 그 결과, 모범 답안에 상당히 근접하게 엔터티를 도출한 것을 확인하였다. 따라서 본 연구에서 제안한 절차가 데이터 모델링에 경험이 없는 초보자가 익숙하지 않은 업무에 적용하더라도 모범 답안에 근접하게 엔터티를 도출할 수 있음이 확인되었다. 엔터티를 제외한 데이터 모델의 핵심요소인 속성과 관계의 도출에 대한 연구는 차후로 미룬다.