• Structural Engineering and Mechanics
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• 제14권5호
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• pp.611-624
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• 2002

In this paper, a complete solution is presented for dynamic plastic response of a rigid, perfectly plastic hinged-free beam, of which one end is simply supported or hinged and the other end free, subjected to a transverse strike by a travelling mass at an arbitrary location along its span. The governing differential equations are expressed in non-dimensional forms and solved numerically to obtain the instantaneous deflection of the beam and the plastic dissipated energy in the beam. The dynamic behavior for a hinged-free beam is more complicated than that of a free-free beam. It transpires that the mass ratio and impact position have significant influence on the final deformation. In the aspect of energy dissipation, unlike simply supported or clamped beams for which the plastic deformation consumes almost the total input energy, a considerable portion of the input energy would be transferred as rigid-body motion of hinged-free beam, and the energy dissipated in its plastic deformation is greatly reduced.

• 한국실내디자인학회논문집
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• 제20권6호
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• pp.53-61
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• 2011

As the standard of living has raised and the local self-governing body has enforced, cultural facilities have been increased in local areas. These cultural facilities should be designed to consider various users. However, most facilities were designed to focus on size or visual expressions. Therefore, this study was intended to evaluate common spaces of two cultural centers in local area from the universal design point of view. Two cultural centers located in large apartment complex were selected. The evaluating tool consisted of 46 elements related to universal design. The common space were pathway to entrance, parking lot, entrance, all over building, corridor, and restroom. Each 100 users of these two cultural centers evaluated them using by 5-point Likert scale. The results were as follows; The users rated them positively, but not highly. This means that some improvement were needed. Generally, the consideration for upgrading the quality of design such as material, pattern and color needed, and for various users including wheelchair users and seniors were needed. Also, when considering the users' behavior pattern and purposes, installing canopy over entrance, and providing seating places at corridor or pathway were needed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1991년도 추계학술발표회 논문집 지반공학에서의 컴퓨터 활용 COMPUTER UTILIZATION IN GEOTECHNICAL ENGINEERING
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• pp.362-375
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• 1991

Background and Necessity of the study : For more than 20 years, the soil engineering reserach group of Chonnam National University has been performing the deformation analysis of soft clayey foundation, since the University is located near the south-western coast of Korean Peninsulla, along which tide reclamation works have been under proaressing. Associsted with the fact mentioned above, the researchers have been developing a computer program in order to carry out deformation analysis of soft foundation since early 1980. Case-studies : In this research, the Biot's equation was selected as the governing equation coupled with several constitutive models including original and modified Cam-clay models, elasto-viscoplastic model, Lade's model etc. The anisotropy of soi1 can be considered in this program. To validate the accuracy of the computer program developed a couple of case-studies were performed. These include the pilot banking, sand drain considering smear effect and compound foundation reinforced with sheet pile into soft foundation.i) The pilot banking Good results could be acquired by assuming banking load as the body force composed of finite element mesh rather than equivalent concentrated load.ii) The sand drain Due to smear, the delay of consolidation was remarkable at the early stsge. so safety for the failure of foundation should be checked for the initial step of consolidation. iii) The compound foundation Accurate results were obtained by introducing the joint element method for the soft foundation reinforced with sheet pile into soiㅣ.

• Advances in nano research
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• 제9권3호
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• pp.133-145
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• 2020

In this study, nonlinear vibrations and dynamic instabilities of a smart embedded micro shell conveying varied fluid flow and subjected to the combined electro-thermo-mechanical loadings are investigated. With the aim of designing new hydraulic sensors and actuators, the piezoelectric materials are employed for the body and the effects of applying electric field on the stability of the system as well as the induced voltage due to the dynamic behavior of the system are studied. The nonlocal piezoelasticity theory and the nonlinear cylindrical shell model in conjunction with the energy approach are utilized to mathematically modeling of the structure. The fluid flow is assumed to be isentropic, incompressible and fully develop, and for more generality of the problem both steady and time dependent flow regimes are considered. The mathematical modeling of fluid flow is also carried out based on a scalar potential function, time mean Navier-Stokes equations and the theory of slip boundary condition. Employing the modified Lagrange equations for open systems, the nonlinear coupled governing equations of motion are achieved and solved via the state space problem; forth order numerical integration and Bolotin's method. In the numerical results, a comprehensive discussion is made on the dynamical instabilities of the system (such as divergence, flutter and parametric resonance). We found that applying positive electric potential field will improve the stability of the system as an actuator or vibration amplitude controller in the micro electro mechanical systems.

• 대한기계학회논문집B
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• 제20권8호
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• pp.2681-2692
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• 1996

The finite-volume method for radiation in a three-dimensional non-orthogonal gas turbine combustion chamber with absorbing, emitting and anisotropically scattering medium is presented. The governing radiative transfer equation and its discretization equation using the step scheme are examined, while geometric relations which transform the Cartesian coordinate to a general body-fitted coordinate are provided to close the finite-volume formulation. The scattering phase function is modeled by a Legendre polynomial series. After a benchmark solution for three-dimensional rectangular combustor is obtained to validate the present formulation, a problem in three-dimensional non-orthogonal gas turbine combustor is investigated by changing such parameters as scattering albedo, scattering phase function and optical thickness. Heat flux in case of isotropic scattering is the same as that of non-scattering with specified heat generation in the medium. Forward scattering is found to produce higher radiative heat flux at hot and cold wall than backward scattering and optical thickness is also shown to play an important role in the problem. Results show that finite-volume method for radiation works well in orthogonal and non-orthogonal systems.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.164-169
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• 2009

Study on swimming of microorganisms like, sperm motility, cilia beating, bacterial flagellar propulsion has found immense significance in the field of biological fluiddynamics. Because of the complexity involved, it is challenging for the researchers to model such problems. Immersed boundary method has proved its efficacy in the field of biological fluiddynamics, The present work aims at performing a numerical study on the microorganism locomotion using the immersed boundary method proposed by Peskin[1]. A two-dimensional model of the microorganism is modeled as thin elastic filament described as a sine wave. The neutrally buoyant organism undergoing deformations is immersed in a viscous and incompressible fluid. The fluid quantities are described using Eulerian coordinates and the immersed body is represented by Lagrangian coordinates. The Eulerian and Lagrangian variables are connected by the Dirac delta function. The Navier-Stokes equations governing the fluid flow are solved using the fractional step method on a staggered Cartesian grid system. The developed numerical code in FORTRAN will be validated by comparing the numerical results with the available results.

• 대한가정학회지
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• 제29권2호
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• pp.1-15
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• 1991

The purpose of this study was to understand the diversity and speciality of Aztec dress which has not been well known, and to overcome ethnocentrism in clothing perceptions. From 15 century to early 16 century, the Aztec empire based on the unique view of the world, most flourished in Mesoamerica. Ritualistic and official side of Aztec life was reflected well on dress. Most Aztec garments consisted of unsewn pieces of cloth, draped on the body as loincloth, mantle and wraparound skirt. Slightly more complicated garments such as women's blouses(huipils) and men's simple jackets were created by sewing together two or more pieces of material. In the sharply stratified world of Aztec, strict sumptuary laws controlled dress. The garments of lower classes were made of maguey or yucca fiber, and only the upper classes were allowed to wear cotton clothing. In addition to material, color, elaborateness and even manner of tieing the mantle were carefully controlled by government edict. As the Aztec empire expanded and became wealthier, the sumptuary laws could not actually dictate what people wore everyday but rather provided a set of rules governing clothing for ceremonial occasions. Aztec's warrior costumes, consisted of headdress, towering back devices, feather garments, were sufficient to suggest the theatrical grandeur of what must have been one of the most magnificiently attired armies ever assembled.

• 대한의용생체공학회:의공학회지
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• 제2권2호
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• pp.89-102
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• 1981

The recirculating flows which occur in the prosthetic heart valve have been known to cause several diseases in the human body. And the recent studies show that the shear stress at the wall of the artery is also very important factor in the formation of thrombus. And many studies knave been devoted in obtaining more information about the blood flow through the prosthetic heart valve. In this Paper, the steady axisymmetric flow through the Disc-Type Heart Valve is studied by using the numerical method. The geometry of the Disc-Type Heart Valve is simplified, and the flow is assumed to be steady axisymmetric flow. The vorticity transport equation derived from the Wavier-Stoke's equation is used as the governing equation, and the explicit finite difference method is used to obtain the steady state solution. The results for several Reynolds numbers show that the recirculating flow becomes large as the Remolds number increases. Furthermore, it can be shown that the magnitudes of the vorticity and the stresses are also increased with the Reynolds number, but there is only a little change in their configurations of distribution and in their positions of maximum values.

• 한국콘텐츠학회논문지
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• 제6권9호
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• pp.67-74
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• 2006

최근, 우리는 국가적으로 유비쿼터스 기술을 기반으로 국가를 경영하고 발전시키는 u-Korea 전략을 제시하였다. 이에 따라 많은 지자체들이 자체적으로 자신의 환경에 가장 적합한 미래 도시를 건설하기 위해 u-City 구축 계획을 작성하고 있다. 본 논문에서는 유비쿼터스 관련 계획들의 동향과 특성을 분석한 후 진주에서 국제 청소년 디지털 영화제를 모바일을 이용한 유비쿼터스 기술 기반으로 기획한다. 그리고 디지털 콘텐츠 산업의 한 분야인 디지털 영화산업 전략을 제안한다. 또한, 이를 바탕으로 본 논문은 진주 전역을 유비쿼터스 서비스가 지원되는 도농 복합형 u-진주를 위한 초기 수준의 연구 방안을 제시한다.

• Korea-Australia Rheology Journal
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• 제18권2호
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• pp.109-118
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• 2006

A finite-element method was employed to analyze axisymmetric unsteady motion of a deformable bubble near the wall. In the present study a deformable bubble in a Newtonian medium near the wall was considered. In solving the governing equations a structured mesh generator was used to describe the collapse of highly deformed bubbles with the Arbitrary Lagrangian Eulerian (ALE) method being employed in order to capture the transient bubble boundary effectively. In order to check the accuracy of the present FE analysis we compared the results of our FE solutions with the result of the collapse of spherical bubbles in a large body of fluid in which solutions can be obtained using a 1D FE analysis. It has been found that 1D and 2D bubble deformations are in good agreement for spherically symmetric problems confirming the validity of the numerical code. Non-spherically symmetric problems were also solved for the collapse of bubble located near a plane solid wall. We have shown that a microjet develops at the bubble boundary away from the wall as already observed experimentally. We have discussed the effect of Reynolds number and distance of the bubble center from the wall on the transient collapse pattern of bubble.