• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.75-78
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• 2003

In order to describe the Bauschinger and transient behavior of orthotropic fiber-reinforced composites, a combined isotropic-kinematic hardening law based on the non-linear kinematic hardening rule was considered here, in particular, based on the Chaboche type law. In this modified constitutive law, the anisotropic evolution of the back-stress was properly accounted for. Also, to represent the orthotropy of composite materials, Hill's 1948 quadratic yield function and the orthotropic elasticity constitutive equations were utilized. Furthermore, the numerical formulation to update the stresses was also developed based on the incremental deformation theory for the boundary value problems. Numerical examples confirmed that the new law based on the anisotropic evolution of the back-stress complies well with the constitutive behavior of highly anisotropic materials such as fiber-reinforced composites.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1769-1775
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• 2004

In presence of collision between two rigid bodies, they exhibit impulsive behavior to generate physically feasible state. When the frictional impulse is involved, collision resolution can not be easily made based on a simple Newton's law or Poisson's law, mainly due to possible change of collision mode during collision, For example, sliding may change to sticking, and then sliding resumes. We first examine two conventional methods: the method of mode evolution by differential equation, and the other by linear complementarity programming. Then, we propose a new method for mode evolution by solving only algebraic equations defining mode changes. Further, our method attains the original nonlinear impulse cone constraint. The numerical simulation will elucidate the advantage of the proposed method as an alternative to conventional ones.

• The Korean Journal of Air & Space Law and Policy
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• v.11
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• pp.301-320
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• 1999

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.6 no.1
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• pp.23-37
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• 2011

This paper is brought to carry out an empirical study whether evolution process of venture firm's scale is following the Gibrat's law; random evolution process, or Pareto law; self-organizing process. The empirical test, as attaching theoretical explanation, of this research utilize the serial data samples of 92 KOSDAQ listed companies from the year of 2005 through 2008. Summarizing the research results are as followed. First, Gini Coefficients representing the density of venture firm's scale has been constantly reduced since the year of 2005 in terms of number of employee, while these index increased during the same time period from the perspective of sales volume. Second, the evolution process of Korea venture firm's scale is following the Power Law related to Pareto Law. In particular, estimated Pareto coefficient, ${\alpha}$, is shown lower than 1 which is significant result. Third, the probability of joining in the top tier group of firm starting from the early stage growing is forecasted into 6.9%, the result which emphasize the starting scale of venture firm play an important role in long term evolution of venture firm.

• The KIPS Transactions:PartD
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• v.14D no.3 s.113
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• pp.293-302
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• 2007

The study of the web graph yields valuable insight into web algorithms for crawling, searching and community discovery, and the sociological phenomena which characterize its evolution, also it is useful for understanding the evolution process of web graph and predicting the scale of the Web. In this paper, we report experimental results on properties of the Korea web graph with over 116 million pages and 2.7 billion links. We indicate to study the Korea web properties such as the power law phenomenon and then to analyze the similarity and difference between the global and Korea web graph. Our analysis reveals the Korea web graph have different properties compared with the global web graph from the structure to the evolution of the Web. Finally, a number of measurements of the evolution of the Korea web graph ill be represented.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.947-952
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• 1996

The effect of fluctuating temperature on the respiration of vegetables has been investigated. Spinach was selected as the experimental material because of its high respiratory activity and kept under the condition that temperature changed alternately at low and high levels every 4 hours. The low-high level temperature combination was set in $1-10^{\circ}C,{\;}1-20^{\circ}C{\;}and{\;}1-30^{\circ}C$. Respiration was evaluated in terms of quantity of $CO_2$ evolved from spinach. The evolution rate of $CO_2$ was determined by a change in its concentration. The evaluation rate of $CO_2$ followed closely the temperature change. In the temperature combinations at $1-10^{\circ}C{\;}and{\;}1-20^{\circ}C$, the relationship between $CO_2$ evolution rate and temperature was found to be able to express by Arrhenius law, while at $1-30^{\circ}C$, it did not obey the law.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10B
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• pp.938-946
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• 2003

Studies of Internet algorithms or policies require experiments on the real large-scale networks. But practical problems with large real networks make them difficult. Instead many researchers use simulations on the Internet topology models. Some tried to find out abstract topological properties of Internet. And several models are proposed to reflect Internet's topological characteristics better. But few studies have been performed on how to model the evolution of Internet. We propose algorithms for modeling addition and removal of nodes and accompanied change of topologies. We analyze the topologies generated by our algorithms to observe that they obey the power-laws better than those generated by existing ones. These algorithms are also expected to be helpful in predicting future topologies of Internet.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.701-710
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• 2002

The framework, described in this paper, involves artificial evolutionary systems that re -produce aimed solutions through a simulated Darwinian evolution process. Through this process the framework designs structures of machines innovatively and emergently especially in the stages of conceptual and basic design. Since the framework simulates the evolution of nature, it inevitably involves processes that converse the natural evolution to the artificial evolution. For the conversion, based on several methods as the building block modeling, Artificial Life, evolutionary computation and the law of natural selection, we propose a series of processes that consists of modeling, evaluation, selection, evolution etc. We have demonstrated the implementation of the framework with the design of multi-step gear systems.

• Structural Engineering and Mechanics
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• v.70 no.6
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• pp.781-791
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• 2019

Earthquakes most often induce damage to structures, resulting in the degradation or deterioration of integrity. In this paper, based on the experimental study on 5 RC frames with different span length and different layout of buckling-restrained braces, the seismic damage evaluation law of RC frame with buckling-restrained braces was analyzed, and then the seismic damage for different specimens was calculated using different damage models to study the damage evolution. By analyzing and comparing the observation in test and the calculated results, it could be found that, damage evolution models including Gosain model, Hwang model as well as Ou model could better simulate the development of damage during cyclic loading. Therefore, these 3 models were utilized to analyze the development of damage to better demonstrate the evolution law for structures with different layout of braces and under different axial compression ratios. The results showed that from all layouts of braces studied, the eccentrically braced frame behaved better under larger deformation with the damage growing slowly. It could be deduced that the link beam benefited the seismic performance of structure and alleviated the damage by absorbing high values of energy.

• Journal of applied mathematics & informatics
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• v.41 no.3
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• pp.487-510
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• 2023

We propose a mathematical model which describes the frictional contact between a piezoelectric body and an electrically conductive foundation. The behavior of the material is described with a linearly electro-viscoelastic constitutive law with long term memory. The mechanical process is dynamic and the electrical conductivity coefficient depends on the total slip rate, the friction is modeled with Tresca's law which the friction bound depends on the total slip rate with taking into account the electrical conductivity of the foundation both. The main results of this paper concern the existence and uniqueness of the weak solution of the model; the proof is based on results for second order evolution variational inequalities with a time-dependent hemivariational inequality in Banach spaces.