• Structural Engineering and Mechanics
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• v.91 no.2
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• pp.123-133
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• 2024

The assessment of seismic behavior and seismic performance of ageing Sarıyar concrete gravity dam constructed on Sakarya River in Türkiye is the main focus of this paper. For this purpose, the impact of sediment domain, ageing of concrete material under the impact of chemical and mechanical actions, and dam-water-sediment interaction are included in the two-dimensional (2D) finite element (FE) model developed in FORTRAN 90 environment. In the FE model, the dam and age dependent sediment domains are modeled by solid elements, while reservoir domain is modeled by Lagrangian fluid elements. The radiation of reflected waves to the unbounded water domain is modeled by infinite Lagrangian fluid elements, while unbounded sediment domain is modeled by infinite solid elements. The coupled system was assumed to be under the simultaneous impact of Vertical (V) and Horizontal (H) ingredients of 1976 Koyna earthquake and the coupled system was analyzed in Laplace domain by direct method. Due to the deterioration of the concrete, the H and V displacement responses together with the fundamental period of the body, elongate throughout the lifetime and this reduce the seismic safety of the dam. It was deduced that the ageing dam body will not experience major damages under the Koyna earthquake both at the earlier and later ages. Furthermore, at the heel of the dam, the hydrodynamic pressure responses are decreased by rising the sediment domain depth.

• Structural Engineering and Mechanics
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• v.48 no.6
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• pp.775-789
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• 2013

The current paper proposes a boundary element formulation, applicable to 2-D and 3-D elastostatics problems using a unified approach for transformations of the domain integrals into boundary integrals. The method is applicable to linear problems encompassing both finite and infinite multi-region domains allowing non-vanishing body forces. Numerical results agree quite well with the analytical solutions; while the present method offers easy formulation with less numerical efforts in comparison to FEM or some BEM which need interior points to treat arbitrary body forces. It is demonstrated that the method has the potential to have profound impact on engineering design, notably in dam-foundation interaction.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.05a
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• pp.157-168
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• 1995

Ignition of a reactive solid with rough surface by constant heat flux is studied. The geometry of surface is represented by a protrusion in shape of cone of infinite length. Ignition time and ignition criterion versus apex angle are determined, with the use of heterogeneous model of ignition. To study the effect of geometry on ignition the results are compared with the known results for the one-dimensional ignition of the semi-infinite body. It is shown, that: a) ignition time depends strongly upon the apex angle and is proportional to the angle to the second power; b) ignition criterion and ignition temperature do not depend strongly on angle. The ignition delay and the energy required for the successful ignition are substantially reduced compared to the one-dimensional case.

• Journal of the Korean Society of Costume
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• v.24
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• pp.143-155
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• 1995

Unlike pure art such as painting and sculpture, dressmaking , a field of special plastic art, is characterized by its physical and functional nature. Having an inseparable relation with form, it is a field of art expressiion the human innersense of beauty in correlation with other various fields of art. In this respect, I think it should be necessary for us to study the forms of art from the past in order to study the forms of art from the past in order to study the correlations and mutual influencies between forms of pure art and dressmaking and to understand modern dressmaking from the standpoint of art. In this context, this study is an attempt to analze how the form and characteristics of OP ART , which represents the trends of the 1960's is embodied in modern dresses. The results are as follows : Fist , the expression of OP ART in dresses have visual effects harmonizing with bodily movements and , also, expanded the range and dynamics of expression which resulted from the introduction of visual phenomena in a fresh new sense by not limiting itself to the suggestion of patterns of OP ART. Second, OP ART paintings expressed the mobility and rhythimicity of a body in a limited space in a two-dimensional plane way of expression . When a dress is worn, however, it expands such mobility and rhythmicity in a cubic , three-dimensional way, maximizing the effects of , and boldly expression, OP ART, it can also create a new silhuette and ability of formation by seeking an open expression of OP ART rather than an expression of OP ART it self , due to the infinite possibility and unpredictability by the dynamics of movements and the elements principle of designs. Third , by applying the patterns of OP ART to dresses, we can obtain special visual effects of design, cover up the body's weak points, and create a desired three -dimensional sense by highlighting the beauty of the body's curved lines. Although modern dresses and OP ART are different genres of art, both have something in common in their pusuits. Since there is a infinite possibility in OP ART, there should be continuous attempts to combine dresses and art satisfying the sense of the times, which will lead dressmaking to a higher-dimensional dressmaking plastic art.

• Journal of the Korean Society of Combustion
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• v.7 no.1
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• pp.31-36
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• 2002

Vortical structures are investigated numerically for both cold and combusting flows from a two-dimensional bluff-body burner in the transitional flow regime from steady to unsteady state. The Reynolds number of the central fuel flow is varied from 10 to 230 at a fixed air Reynolds number of 400. The flame sheet model of infinite chemical reaction and unit Lewis number are assumed in the simulation. The temperature dependence of the viscosity and diffusivity of the gas mixture is also considered. The vortex shedding is observed depending on the fuel flow. For cold flow, four different types of vortical structure are identified. However, for combusting flow of methane-air system the vortical structures change significantly due to a large amount of heat release during the combustion process, in contract to cold flow.

• Journal of Ship and Ocean Technology
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• v.7 no.2
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• pp.1-19
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• 2003

This paper introduces a unified theory for the radiation problem of adjacent multiple floating bodies. The particular case of interest is the multiple slender bodies that their centerlines are parallel. The infinite-and finite-depth unified theories for the single-body problem are extended to solve each sub-problem of multiple bodies. The present method is valid for deep water and moderate water depth, and applicable for individually floating bodies as well as multimaran-type vehicles. For the validation of the present method, the heave and pitch hydrodynamic coefficients for two adjacent ships are compared with the results of a three-dimensional method, and an excellent agreement is shown. The application includes the hydrodynamic coefficients and motion RAOs of four trimarans which have different longitudinal and transverse arrangements for sidehulls.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.238-243
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• 1981

An empirical formula for the mass flow rate in natural convection flume above a spherical heated body which is submerged in a finite fluid contained in a tank was determined. The ratio of depth of submergence to diameter of the sphere for which the sphere sensed as infinite medium was found to be bigger than 7. A dimensionless heat transfer correlation for the natural convection from a sphere was determined for Gr.Prq etween 7x10$\^$7/ and 2x10$\^$8/ also.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.79-81
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• 2008

2차원균열을 포함하고 있는 무한체가 균일한 전단응력을 받고 있는 경우에 대한 복소응력함수를 기존의 응력함수를 이용하여 해석적으로 구하였다. 이는 등각사상과 정칙연속법에 의하여 구하였다. 결과는 극한의 경우에 대하여 검증하였으며 구한 복소응력함수는 맞는다는 것을 보여준다.

• Journal of Advanced Marine Engineering and Technology
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• v.14 no.2
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• pp.48-65
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• 1990

Numerical solutions of the Navier-Stokes equations, governing 2-dimensional, time-dependent, viscous, incompressible fluid flow past a square cylinde in an infinite region, are presented for Reynolds numbers $10^2$, $10^3$and $10^4$. Finite-difference scheme, based on SOLA-VOF is adopted and a discretization of the convection term for irregular grid is newly suggested by altering the original nonconservation form into conservation one. Distribution of finer grids around the body reveals fairly reasonable consistency with the experimental variables : drag coefficient, lift coefficient, Strouhal number, fluctuating pressure coefficient, etc.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.11
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• pp.1146-1154
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• 2008

This paper presents a method for the acceleration analysis of multi-legged walking robots in consideration of the frictional ground contact. This method is based on both unified dynamic equation for finding the acceleration of a robot's body and constraint equation for satisfying no-slip condition. After the dynamic equation representing relationship between actuator torques and body acceleration, is derived from the force and acceleration relationship between foot and body's gravity center, the constraint equation is formulated to reconfigure the maximum torque boundaries satisfying no-slip condition from given original actuator torque boundaries. From application of the reconfigured torques to the dynamic equation, interested acceleration boundaries are obtained. The approach based on above two equations, is adapted to the changes of degree-of-freedoms of legs as well as friction of ground. And the method provides the maximum translational and rotational acceleration boundaries of body's center that are achievable in every direction without occurring slipping at the contact points or saturating all actuators. Given the torque limits in infinite normsense, the resultant accelerations are derived as a polytope. From the proposed method, we obtained achievable acceleration boundaries of 4-legged and 6-legged walking robot system successfully.