• Structural Engineering and Mechanics
• /
• v.21 no.6
• /
• pp.659-676
• /
• 2005

The novel form of composite walling system consists of two skins of profiled steel sheeting with an in-fill of concrete. The behaviour of such walling under in-plane shear is important in order to utilise this system as shear elements in a steel framed building. Steel sheet-concrete interface governs composite action, overall behaviour and failure modes of such walls. This paper describes the finite element (FE) modelling of the shear behaviour of walls with particular emphasis on the simulation of steel-concrete interface. The modelling of complex non-linear steel-concrete interaction in composite walls is conducted by using different FE models. Four FE models are developed and characterized by their approaches to simulate steel-concrete interface behaviour allowing either full or partial composite action. Non-linear interface or joint elements are introduced between steel and concrete to simulate partial composite action that allows steel-concrete in-plane slip or out of plane separation. The properties of such interface/joint elements are optimised through extensive parametric FE analysis using experimental results to achieve reliable and accurate simulation of actual steel-concrete interaction in a wall. The performance of developed FE models is validated through small-scale model tests. FE models are found to simulate strength, stiffness and strain characteristics reasonably well. The performance of a model with joint elements connecting steel and concrete layers is found better than full composite (without interface or joint elements) and other models with interface elements. The proposed FE model can be used to simulate the shear behaviour of composite walls in practical situation.

• Structural Engineering and Mechanics
• /
• v.41 no.6
• /
• pp.711-734
• /
• 2012

The foundation of a tall building frame resting on settable soil mass undergoes differential settlements which alter the forces in the structural members significantly. For tall buildings it is essential to consider seismic forces in analysis. The building frame, foundation and soil mass are considered to act as single integral compatible structural unit. The stress-strain characteristics of the supporting soil play a vital role in the interaction analysis. The resulting differential settlements of the soil mass are responsible for the redistribution of forces in the superstructure. In the present work, the nonlinear interaction analysis of a two-bay ten-storey plane building frame- layered soil system under seismic loading has been carried out using the coupled finite-infinite elements. The frame has been considered to act in linear elastic manner while the soil mass to act as nonlinear elastic manner. The subsoil in reality exists in layered formation and consists of various soil layers having different properties. Each individual soil layer in reality can be considered to behave in nonlinear manner. The nonlinear layered system as a whole will undergo differential settlements. Thus, it becomes essential to study the structural behaviour of a structure resting on such nonlinear composite layered soil system. The nonlinear constitutive hyperbolic soil model available in the literature is adopted to model the nonlinear behaviour of the soil mass. The structural behaviour of the interaction system is investigated as the shear forces and bending moments in superstructure get significantly altered due to differential settlements of the soil mass.

• Fire Science and Engineering
• /
• v.28 no.5
• /
• pp.37-43
• /
• 2014

In the case of interior fire in an apartment building, contamination of vestibule area by fire smoke before air fan operating when fire doors are open makes the evacuation of people very difficult. In order to investigate the effect of heat release rate (HRR) and interior opening on fire flow velocity, numerical simulations using Fire Dynamics Simulator were carried out. In simulations, actual dimensions and configuration of an apartment building were considered and interior leakage and HRR were varied. From simulation results, it was found that fire flow velocity distribution is significantly influenced by HRR and interior opening resulting in the change of the location of a neutral plane. Also, it is shown that there is a larger difference of the fire flow velocity between upper and lower part of the fire door when the neutral plane becomes closer to the ceiling.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.27 no.3
• /
• pp.58-68
• /
• 1999

Purpose of this thesis is to find out the relationship among the amount of change and the visual cognition, and the visual preference which people like and can feel. Through the investigation of relationships between the amount of change, which indicates the degree of visual variation and the visual preference, the amount of change and the visual cognition, and the visual preference and the visual cognition, basic design data will be supplied, which can satisfy users' desire as much as possible in the most economic way. In order to investigate the relationship between the visually produced the amount of change and preferences, graphic simulation, in which variables other than the visual change are controlled, has been proceeded. Graphic factors of the visual change in the cyber exterior space are determined on the point of location (base plane, vertical plane, overhead plane), shape, size and color. As for the relationship between the amount of change and the preference, only the size is effective. since preferences on the location, shape and color are individual preferences, no common trend can be found. Therefore, we cannot say that which shape or color is better, Since the location, shape and color are qualitative change and the size is the quantitative change, the size can be the measurable change quantity. The relationship between the amount of change of size and the degree of preference is found to be inverse U-shape, i.e., as the amount of change of size increases the degree of preference first increases and, after a certain level, decreases. The same result has been obtained in photo simulation.

• School Mathematics
• /
• v.10 no.3
• /
• pp.423-441
• /
• 2008

The purpose of this study was to examine the Pedagogical Content Knowledge(PCK) of teachers and their educational practice in the category of plane figure, to make a comparative analysis of their PCK and educational practice, and to discuss the relationship between their PCK and the characteristics of their instruction. Instruction of four selected elementary school teachers was analyzed to find out their educational practice. In conclusion, the characteristics of the PCK and actual instruction of the teachers could be listed as below: First, as a result of comparing their PCK and educational practice on plane figure by applying selected analysis criteria, there was a close correlation between their PCK and actual instruction. Second, the teachers had various levels of PCK on different areas. Especially, there was a large disparity in mathematical content knowledge and knowledge of teaching methods. Third, the teachers who had plenty of PCK were more excellent in textbook reconstructing, and those who fell behind in terms of PCK were more reliant on textbooks as if the textbooks had been the Bible.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.5
• /
• pp.563-571
• /
• 2012

In 3D integration package using TSV technology, bonding is the core technology for stacking and interconnecting the chips or wafers. During bonding process, however, warpage and high stress are introduced, and will lead to the misalignment problem between two chips being bonded and failure of the chips. In this paper, a finite element approach is used to predict the warpages and stresses during the bonding process. In particular, in-plane deformation which directly affects the bonding misalignment is closely analyzed. Three types of bonding technology, which are Sn-Ag solder bonding, Cu-Cu direct bonding and SiO2 direct bonding, are compared. Numerical analysis indicates that warpage and stress are accumulated and become larger for each bonding step. In-plane deformation is much larger than out-of-plane deformation during bonding process. Cu-Cu bonding shows the largest warpage, while SiO2 direct bonding shows the smallest warpage. For stress, Sn-Ag solder bonding shows the largest stress, while Cu-Cu bonding shows the smallest. The stress is mainly concentrated at the interface between the via hole and silicon chip or via hole and bonding area. Misalignment induced during Cu-Cu and Sn-Ag solder bonding is equal to or larger than the size of via diameter, therefore should be reduced by lowering bonding temperature and proper selection of package materials.

• Journal of Mechanical Science and Technology
• /
• v.19 no.3
• /
• pp.778-791
• /
• 2005

A novel pneumatic artificial muscle actuator (PAM actuator), which has achieved increased popularity to provide the advantages such as high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks, has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators. However, some limitations still exist, such as the air compressibility and the lack of damping ability of the actuator bring the dynamic delay of the pressure response and cause the oscillatory motion. Then it is not easy to realize the performance of transient response of pneumatic artificial muscle manipulator (PAM manipulator) due to the changes in the external inertia load with high speed. In order to realize satisfactory control performance, a variable damper-Magneto­Rheological Brake (MRB), is equipped to the joint of the manipulator. Superb mixture of conventional PID controller and a phase plane switching control method brings us a novel controller. This proposed controller is appropriate for a kind of plants with nonlinearity, uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control method and without regard for the changes of external inertia loads.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.34 no.2
• /
• pp.49-59
• /
• 1992

In our researches we made mix-design, with the mixing ratio and pre-cracked ratio of steel fibrous different from each other, building the steel fibrous concrete beam which had pre-cracks. To obtain the fracture characteristics of steel fibrous reinforced concrete, series of experiment were conducted on pre-cracked beam subjected to 3-point bending. Thus, we carried out experiments on the destructive characteristics of its pre-crack and post-crack and the result is as follows. 1. The compressive strength of steel fibrous concrete beam increased more slightly than plane beam, and the tensile strength increased 37%, 59%, 94% and 121% respectively when the amount of fibrous was 0.5%, 0.1% 1.5%, and 1.75% respectively. 2. As the amount of steel fibrous mixing increased ant the steel fibrous inhibited the crack growth, the crack condition of steel fibrous concrete beam was retarded irregularly, and this increased fracture load. 3. The defiance of destruction was reduced in the ratio of 1.35 times and 1.22 times respectively when the length of pre-crack was each 2cm and 4cm in comparison with the case of being without the length, and was similar to that of plane beam when the amount of steel fibrous mixing was below 1.0%, and increased linearly when it as above 1.0%. 4. The experimental formula seeking fracture energy was follows and thus we found that the value of fracture energy depended upon tensile strength and the size of speciment. $G_f=K\;{\cdot}\;f_f^'{\cdot}$da/Ec 5. We observed that in the load-strain curve of steel fibrous concrete beam the progress of the crack became slow, compared with plane beam because the crack condition became long to the extent of about 10 times. Concrete was faultiest brittleness fracture through the study, it was known ductile.

• Journal of the Society of Naval Architects of Korea
• /
• v.59 no.5
• /
• pp.288-295
• /
• 2022

In this study, the force and moment acting on a Joubert BB2 submarine model at depths near the free surface were measured through a captive model test with the scale ratio of 1/15. Based on the experiment, the pitch moment and heave force due to the "Tail suction effect", including the change in surge force with depth near the free surface, were quantitatively analyzed. The change of force and moment according to the relative position of the sail and the free surface was reviewed with the free surface waves generated for each depths. As a result, the angle of attack of the hull to counteract the pitch moment induced by the tail suction effect was derived. The effect of the hydrostatic moment component according to the angle of attack on the equilibrium of pitch moment was also taken into account. The control plane performance tests for the X-type rudder and sail plane were conducted in snorkel and surface depth conditions to figure out the control plane angles for the neutral level flight of the submarine at near free surface. The results of this study are expected to be used as a reference data for the neutral level flight of the submarine at near free surface operation in the free running model test as well as numerical studies.

• Journal of the Korean Society of Radiology
• /
• v.9 no.7
• /
• pp.501-508
• /
• 2015

There are various Intercondyloid fossa X-ray taking methods. The methods carried out in clinics are Holmblad method, Camp-Conventry method, and Beclere method. Taking image of Intercondyloid fossa is carried a lot as basic examination for diagnosis related to simple fracture and cruciate ligament. Considering the condition and pains of patients, safe method is chosen but because Holmblad method can cause pains to knee part adhering to cassette, it is not easily used. In this study self-produced plane circular cone was attached to a cassette and in the posture for Holmblad method questionnaires of 100 applicants were analyzed to understand cognition on alleviation of pains, and the concentration of imge quality by scattering rays was measured with densitometer by taking human body phantom with X-ray. As a result, in the posture for Holmblad method, cognition on pains was alleviated by average 99%, and the change of concentration of X-ray film taken using phantom by scattering rays decreased statistically significantly compared to the cassette which did not use self-produced plane cone, therefor it is thought that the method can be valuably used in clinics.