• Structural Engineering and Mechanics
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• v.40 no.1
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• pp.49-64
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• 2011

An analytical method is presented to investigate electromagnetothermoelastic behaviors of a hollow sphere composed of functionally graded piezoelectric material (FGPM), placed in a uniform magnetic field, subjected to electric, thermal and mechanical loads. For the case that material properties obey an identical power law in the radial direction of the FGPM hollow sphere, exact solutions for electric displacement, stresses, electric potential and perturbation of magnetic field vector in the FGPM hollow sphere are determined by using the infinitesimal theory of electromagnetothermoelasticity. Some useful discussion and numerical examples are presented to show the significant influence of material inhomogeneity. The aim of this research is to understand the effect of composition on electromagnetothermoelastic stresses and to design optimum FGPM hollow spheres.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.343-351
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• 2018

Purpose: Recently, As the size of the structure increased, the necessity of reducing its weight was raised. To reduce weight In concrete structures, a hollow slab is proposed as an alternative for weight reduction effect. Method: It is difficult to construct the hollow body due to buoyancy, and the shear performance is insufficient due to the decreased cross section. Slabs were fabricated using unidirectional hollow bodies such as PVC pipes, and experiments were conducted about construction performance and structural performance. Results: The buoyancy preventive device has been improved the construction performance by preventing floating hollow body, it has been confirmed that it has adequate performance to be used as a hollow slab system because it has enough expected shear performance. Coclusion: Hollow ratio has a little connection with bending performance, but after the yielding load, it is necessary to consider the secondary stiffness of structure, and is is supposed that the decrease of shear performance with the increase of hollow core ratio can be complemented with shear reinforcement.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.974-978
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• 2007

In this paper, the requirements of passive levitation for nonmagnetic body in magnetic fluid are investigated. The passive levitation system includes the electromagnetic system composed of two hollow solenoids, the magnetic fluid and the nonmagnetic body made of aluminum. The hollow solenoids generate nonuniform magnetic fields, leading to the gradient of the magnetic field in magnetic fluid. Hence, the resultant magnetic body force in magnetic fluid is used to levitate the nonmagnetic body in the opposite direction of the gravitation. The levitation conditions according to applied current and the mass of the nonmagnetic body are obtained analytically.

• Journal of Mechanical Science and Technology
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• v.16 no.11
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• pp.1470-1476
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• 2002

The goal of this work is to design and build an implantable artificial lung that can be inserted as a whole into a large vein in the body with the least effect on cardiovascular hemodynamics. The experimental results demonstrate that the pressure drop is not entirely related to viscosity effects. The friction factor decreases with an increase in the number of tied-hollow fibers at a constant Reynolds number A uniform flow pattern without stagnation is observed at all numbers of tied hollow fibers tested. The tied hollow fiber module, built in this study with 3 cm of outer diameter of module. 380 m of outer diameter of tied hollow fiber, and 700 number of tied hollow fiber with length of 60 cm, which shows a pressure drop of 13-16 mmHg, satisfies the required pressure drop qualifying 15 mmHg as an intravascular artificial lung.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.3
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• pp.69-75
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• 2010

A hollow flanged spindle is generally used for the assembly of the driving shaft in some vehicles. This part has conventionally been manufactured by both hot forging and machining process, in which case a circular billet is hot-forged into a flanged spindle blank and then its central part is machined for hollow. Therefore, the development of a new forming technology without further machining processes has strongly been in demand. In this study, a new compound forging process of the hollow flanged spindle was proposed through the finite element simulation. By the proposed compound forging process, both extruding of the spindle body part and piercing for the hollow inside it can be performed at the same time. Metal flow patterns, forging defects and forging forces were investigated through the finite element simulation results.

• Journal of the Korean Ceramic Society
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• v.48 no.3
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• pp.228-235
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• 2011

Sintering behavior and lightweight characteristics of porcelain by addition of FAHM (Fly-Ash Hollow Microsphere) were evaluated. Green body of Backja composition (general porcelain) in which FAHM was added(15 and 20 wt%) was made by slip casting method. The green body was sintered at 1270 and $1290^{\circ}C$ and maintained for 1h. The bulk density and linear shrinkage of the sintered body with FAHM (20 wt%) decreased. As the contents of FAHM. increased, mullite and cristobalite phases increased. In the microstructure, FAHM shells remained after sintering, and the generation of mullite fibers around FAHM shells also were confirmed. the weight of porcelain with of 20% FAHM decreased by 40% and residual FAHM shells promoted the mullite of generation in the matrix.

• Journal of Korean Medical classics
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• v.25 no.4
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• pp.57-63
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• 2012

Objective & Method : We investigated the identity of tri-energizer, which was originally described in Huang Di Nei Jing and claimed by traditional scholars, and drew the following conclusions. Result & Conclusion : According to Huang Di Nei Jing tri-energizer is one of the six hollow-organs and is called hollow organs for digestion and elimination, water guffer organ, or solitary hollow organ. It is believed that tri-energizer is regarded as the existing entity based on following several different sources; it functions as the course of channels, regulates wind and link and physiological function-especially intrinsic function of upper, middle, lower internal organs. It also controls syndromes and dysfunction of an illness, the surface of the body, and the cracked surface of the skin. Finally, bold and timidity depend on the tri-energizer. Experts determined the true nature of tri-energizer types. Experts include: Yu Tuan from the Ming dynasty, Tang Jong Hai and Ye Lin from the Qing dynasty, and Zhang Xi Chun from the Zhunghua Minguo period. These experts' claims are based on shape and forms of tri-energizer. Our examinations of anatomical and physiological basis on tri-energizers showed that, in a narrow sense, tri-energizer indicates visceral and parietal peritoneum and omentum surrounding the internal organs, and in a broad sense, indicates the overall membrane wrapping around the whole internal organs including five visceral organs and six hollow organs.

• Transactions of Materials Processing
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• v.9 no.4
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• pp.362-371
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• 2000

In order to reduce weight of a high-speed railroad vehicle, the main body has been manufactured by hollow section extrusion using aluminum alloys. A porthole die has utilized for the hollow section extrusion process, which causes complicated die geometry and flow characteristics. Design of porthole die is very difficult due to such a complexity. The three-dimensional finite element analysis for hollow section is also an arduous job from the viewpoint of appropriate mesh construction and tremendous computation time. In the present work, mismatching refinement, an efficient domain decomposition method with different mesh density for each subdomain, is implemented for the analysis of the hollow section extrusion process. In addition, a modified grid-based approach with the surface element layer is utilized lot three-dimensional mesh generation of a complicated shape with hexahedral elements. The effects of porthole design are discussed through the simulation for extrusion of an underframe part of a railroad vehicle. An experiment has also been carried out for the comparison. Comparing the velocity distribution at the outlet with the thickness variation of the extruded part, it is concluded that the analysis results can provide reliable measures whether the die design is acceptable to obtain uniform part thickness. The analysis results are then successfully reflected on the industrial porthole die design.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.403-409
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• 2015

Porous alumina ceramics are involved in many industrial applications due to the exceptional properties of these products. This study addresses the preparation of porous alumina ceramics using hollow microspheres as a pore-forming agent and slip casting as a green-body-forming technique. A uniform distribution of pores is a basic requirement of a porous material. This study investigates three different slurry systems, i.e., as-prepared alumina slurry, alumina slurry electrostatically dispersed by hydrochloric acid (HCl), and slurry dispersed by the commercial dispersant 'Darvan C-N'. At a low viscosity, the hollow microspheres in the slurry tend to float, which causes a non-uniform pore distribution. To avoid this phenomenon, the viscosity of the slurry was increased to the extent that the movement of hollow microspheres ceased in the slurry. As a result, a uniform pore distribution was achieved.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.954-959
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• 2003

Colonoscopy is an important medical procedure for the diagnosis of various diseases like cancers in the colon and rectum. But it requires a lot of time for a doctor to acquire dexterous skills necessary to perform successful colonoscopy. Moreover, to many patients, conventional colonoscopy simply takes too long time. Therefore, some studies on the development of autonomous and more convenient colonoscope are carried out. In this Paper, we Propose a functional colonoscope robot system that has a locomotive function with a hollow body, a steering system, and other basic functions of typical conventional colonoscope systems. The concept and each component of the functional colonoscope system are described in this paper. In order to evaluate the functional performance of the colonoscope robot, we carried out in -vitro and in-vivo tests.