• Structural Engineering and Mechanics
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• 제64권5호
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• pp.591-610
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• 2017

This paper is concerned with the static analysis of variable thickness of two directional functionally graded porous materials (FGPM) circular plate resting on a gradient hybrid foundation (Horvath-Colasanti type) with friction force and subjected to compound mechanical loads (e.g., transverse, in-plane shear traction and concentrated force at the center of the plate).The governing state equations are derived in terms of displacements based on the 3D theory of elasticity, assuming the elastic coefficients of the plate material except the Poisson's ratio varying continuously throughout the thickness and radial directions according to an exponential function. These equations are solved semi-analytically by employing the state space method (SSM) and one-dimensional differential quadrature (DQ) rule to obtain the displacements and stress components of the FGPM plate. The effect of concentrated force at the center of the plate is approximated with the shear force, uniformly distributed over the inner boundary of a FGPM annular plate. In addition to verification study and convergence analysis, numerical results are displayed to show the effect of material heterogeneity indices, foundation stiffness coefficients, foundation gradient indices, loads ratio, thickness to radius ratio, compressibility, porosity and friction coefficient of the foundation on the static behavior of the plate. Finally, the responses of FG and FG porous material circular plates to compound mechanical loads are compared.

• 대한조선학회논문집
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• 제53권4호
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• pp.300-306
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• 2016

The gas ventilated by supercavitation splits into smaller bubbles and follows the water passage of the cavitation tunnel. The bubbles quickly return to the test section by rather high speed flow, and interrupt the observation of the supercavitation. To secure clear observation in the test section, the bubble collecting section(settling chamber) of large volume is prepared to collect bubbles in the water passage ahead of the test section. The bubble collecting section should provide enough buoyancy effect to the bubbles for proper bubble collecting. However, rather high-speed oncoming flow produces non-uniform velocity distribution and deteriorates buoyancy effect in the bubble collecting section. In the present study, the bubble collecting space and three porous plates are designed and analyzed through numerical methods, and the bubble collecting function is experimentally validated by 1/10-scaled model in terms of the formation of uniformly low velocity distribution in the bubble collecting section.

• 대한기계학회논문집A
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• 제20권2호
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• pp.450-460
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• 1996

To investigate the effect of stress wave propagation for crack tip, impact responses of two-dimensional plates with oblique cracks are investigated by a numerical method. In the numerical analysis, the finite element method is used in space domain discretization and the Newmark constant acceleration algorithm is used in time integration. According to the numerical results from the impact response analysis. it is found that the stress fields are bisected at the crack surface and the parts of stress intensity are moved along the crack face. The crack tip stress fields are yaried rapidly. The magnitude of crack tip stress fields are converted to dynamic stress intensity factor. Dynamic sress intensity factor appears when the stress wave has reached at the crack tip and the aspect of change of dynamic stress intensity factor is shown to be the same as the part of the flow of stress intensity.

• 한국안전학회지
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• 제20권1호
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• pp.75-80
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• 2005

In this paper, when CF/EPOXY laminates for high efficiency space structure are subjected to FOD(Foreign Object Damage), the effects of temperature change on the impact damages(inter laminar separation and transverse crack) of CF/EPOXY laminates and the relationship between residual life and impact damages ale experimentally investigated. Composite laminates used in this experiment are CF/EPOXY orthotropic laminated plates, which have two-interfaces $[0^{\circ}_6/90^{\circ}_6]S$ and four-interfaces $[0^{\circ}_3/90^{\circ}_6/0^{\circ}_3]S$. CF/EPOXY specimens with impact damages caused by a steel ball launched from the air gun were observed by the scanning acoustic microscope under room and high temperatures. In this experimental results, various relations were experimentally observed including the delamination area vs. temperature change, the bending strength vs. impact energy and the residual bending strength vs. impact damage of CF/EPOXY laminates. And as the temperature of CF/PEEK laminates increases, the delaminaion areas of impact-induced damages decrease linearly. A linear relationship between the impact energy and the delamination areas were observed. As the temperature of CF/PEEK laminates increases, the delamination areas decrease because of higher initial delaminatin damage energy.

• 대한조선학회논문집
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• 제31권4호
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• pp.109-118
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• 1994

본 연구에서는 쌍동형 표면효과선 선체 구조의 최소 중량 설계를 수행하는 방법을 제시하고, 이에 따르는 전산 프로그램을 개발하고자 한다. 본 방법은 DnV의 설계 하중 및 강도 기준을 이용하며, 격자 구조 해석을 통해 종거어더와 횡늑골의 상호 영향을 반영하여 설계에 활용하고, 쌍동 선체 사이의 연결 구조에 대해 비틂 강도 해석을 수행하여 횡격벽 설계를 수행한다. 또한 부분구조의 최적화를 통해 중앙 단면 전체의 최적화에 도달하는 방법을 적용함으로써 최적화의 효율을 증가시키고 있다. 본 방법을 적용한 결과, 초기 설계 결과에 비해 20% 정도의 선체 중량 감소효과를 확인할 수 있고, 최적의 횡늑골 간격도 계산될 수 있다.

• Computers and Concrete
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• 제20권6호
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• pp.731-738
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• 2017

Reinforced concrete flat plates consist of slabs supported directly on columns. The absence of beams makes these systems attractive due to advantages such as economical formwork, shorter construction time, less total building height with more clear space and architectural flexibility. Punching shear failure is usually the governing failure mode of flat plate structures. Punching failure is brittle in nature which induces more vulnerability to this type of structure. To analyze the flat plate behavior under punching shear, twelve finite element models of flat plate on a column with different parameters have been developed and verified with experimental results. The maximum range of variation of punching stress, obtained numerically, is within 10% of the experimental results. Additional finite element models have been developed to analyze the influence of integrity reinforcement, clear cover and column reinforcement. Variation of clear cover influences the punching capacity of flat plate. Proposed finite element model can be a substitute to mechanical model to understand the influence of clear cover. Variation of slab thickness along with column reinforcement has noteworthy impact on punching capacity. From the study it has been noted that integrity reinforcement can increase the punching capacity as much as 19 percent in terms of force and 101 percent in terms of deformation.

• 한국식생활문화학회지
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• 제24권1호
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• pp.23-32
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• 2009

This study was conducted to generate fundamental data required by food coordinators and food space creators for planning and directing table settings. The results of this study were then used to suggest an ideal model of table settings for Korean-style food equipped with simple, sophisticated, and practical characteristics. Specifically, this study evaluated the importance of hygiene (safety, cleanness, arrangement), decoration (dignity, form, stylishness, presentation of food on plates), naturalness (seasonal beauty, comfortableness, natural beauty), and modernity (modern style, chic style, urban style). These factors were evaluated according to the preference of the table setting and the characteristics of the meeting, which fit various meal cultures, times, places, and objectives. The results of this study indicate that people prefer hygiene and decoration for family meetings (bansang setting), hygiene and modernity for friendly meetings (simple buffet setting), hygiene and decoration for company meetings (simple buffet setting), and hygiene and decoration for academic meetings (tea party). Hygiene and decoration were highly evaluated in most cases, which indicates that individuals at meetings for special purposes give weight to the meeting's atmosphere, but also consider the hygiene and cleanliness of the food.

• Archives of Reconstructive Microsurgery
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• 제23권2호
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• pp.89-92
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• 2014

An 8-year-old girl diagnosed with dilated cardiomyopathy and Russell-Silver syndrome was admitted to our pediatric intensive care unit due to low cardiac output and multiple-organ dysfunction. The patient was placed on the heart transplant waiting list and extracorporeal membrane oxygenation was performed as a bridge to transplantation. After 17 days, heart transplantation was performed. The donor was a 46-year-old female (weight, 50 kg; height, 150 cm). The donor:recipient weight ratio was 3.37:1. Because the dimension and volume of the recipient's thoracic cage were insufficient, the sternum could not be closed. Nine days after transplantation, the patient underwent delayed sternal closure. To obtain adequate space, we left the sternum 4.5 cm apart from each margin using four transverse titanium plates. A transverse rectus abdominis musculocutaneous flap was chosen to cover the wound. Due to the shortage of donors, a size-mismatched pediatric heart transplantation is sometimes unavoidable. Closure of the opened sternum of a transplant recipient can be challenging. Sternal reconstruction after an extremely oversized heart transplantation with transverse titanium plate fixation and a musculocutaneous flap can effectively achieve sternal closure and stability.

• Structural Engineering and Mechanics
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• 제90권4호
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• pp.345-356
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• 2024

This paper aims to investigate the seismic behavior of double steel plate and concrete composite shear wall (DSCW) of shield buildings in nuclear power engineering through experimental study. Hence, a total of 10 specimens were tested to investigate the hysteretic performance of DSCW specimens in detail, in terms of load vs. displacement hysteretic curves, skeleton curves, failure modes, flexural strength, energy dissipation capacity. The experimental results indicated that the thickness of steel plate, vertical load and stiffener have great influence on the shear bearing capacity of shear wall, and the stud space has limited influence on the shear capacity. And finally, a novel simplified formula was proposed to predict the shear bearing capacity of composite shear wall. The predicted results showed satisfactory agreement with the experimental results.

• 한국안전학회지
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• 제30권3호
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• pp.107-113
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• 2015

The goal of this paper is to investigate structural integrity factors of RMI(reflective metal insulation) to confirm the design requirements in nuclear power plant. Currently, a glass wool insulation is using now, but it will gradually be replaced with the reflective metal insulation maded by stainless steel plates. The main function of an insulation is to minimize a heat loss of vessel and pipes in RCS(reactor coolant system). It has to maintain structural a integrity in nuclear power plant life duration. In this study, the structural integrity analysis was carried out both multi-plate and outer shell plate by using a static analysis and experimental test. First, inner multi-plate has a self support structure for being air space. Because the effect of total static weight in multi-layer plate is low, a plate collapse possibility is not high. Considering optimum thin plate pressing process, it has to pre-check the basic physical properties. Second, the outer segment thickness and stiffener shape are verified by the numerical static analysis, and sample test for both type of panel and cylindrical pipe model.