• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.147-152
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• 2006

This paper presents the dynamic characteristics of MR impact damper for vehicle collision system. Various types of mechanism have been proposed for reduce transmitted force to vehicle chassis and finally protect occupants from injury. In the case of frontal collision, the bumper make main role of isolation material for collision attenuation. In this study, proposed bumper system composed of MR impact damper and structures. The MR impact damper is to adopted MR fluid which has reversible properties with applied magnetic field. MR fluid operates under flow mode with Bingham flow and bellows is used for generation of fluid flow. Mathematical model of MR impact damper incorporated with MR fluid is established. Field dependent damping force is investigated with time and frequency domain. The MR impact damper is then incorporated with vehicle crash system. The governing equation of motion of vehicle model is formulated considering occupant model. Dynamic characteristics of vehicle collision system investigated with computer simulation.

• Journal for History of Mathematics
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• v.28 no.6
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• pp.301-310
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• 2015

Since Jiuzhang Suanshu, the main tools in the theory of right triangles, known as Gougushu in East Asia were algebraic identities about three sides of a right triangle derived from the Pythagorean theorem. Using tianyuanshu up to siyuanshu, Song-Yuan mathematicians could skip over those identities in the theory. Chinese Mathematics in the 17-18th centuries were mainly concerned with the identities along with the western geometrical proofs. Jeong Yag-yong (1762-1836), a well known Joseon scholar and writer of the school of Silhak, noticed that those identities can be derived through algebra and then wrote Gugo Wonlyu (勾股源流) in the early 19th century. We show that Jeong reveals the algebraic structure of polynomials with the three indeterminates in the book along with their order structure. Although the title refers to right triangles, it is the first pure algebra book in Joseon mathematics, if not in East Asia.

• International Journal of Automotive Technology
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• v.2 no.1
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• pp.17-23
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• 2001

Measurements of the initial values lead to an inverse and mathematically unprecisely formulated problem. A precise definition of an inverse problem is possible. It is to state a mathematical model of a physical process with clearly defined initial and exit values for the system behind the process. One can grasp the idea of an inverse problem by considering the tire as a copy of the objects of nature in a room with observations. Interpretation of nature is generally a result of an inverse problem. On one hand, the tire may be represented through the sensory organs and the nervous system as well as the experiences of the developer's existing apparatus of the projection of reality. On the other hand, it may be represented by a physical law or a model that can be confirmed or is to be refuted with the help of suitable measurements. During reconstruction of a measuring signal and the identification of a black box that can be assumed to be linear and causal, the tire becomes a first type Volterra integral equation of the convolution type. But measurements of the initial values are always fuzzy, the errors grow and the system behavior can no longer be forecasted. Thus, we have to deal with a chaotic system. This chaos produces fractals in a natural way. These are self-similar geometric structures. This self-similarity is clearly visible in the design.

• Journal for History of Mathematics
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• v.18 no.3
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• pp.79-90
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• 2005

Before the First World War, French mathematicians were leading mathematical community in the world but after the war, there was a vacuum compared with Germany and England. So it was necessary to make everything new in France. Young mathematicians from Ecole Normale Superieur came together to form the Bourbaki group. Bourbaki advanced the view that mathematics is a science dealing with structures, and that it attains its results through a systematic application of the modern axiomatic method. French culture movements, especially structuralism and potential literature, including the Bourbakist endeavor, emerged together, each strengthening the public appeal of the others through constant interaction. In this paper, we investigate Bourbaki's role and their achievements in the twentieth century mathematics, and the decline of Bourbaki.

• Journal for History of Mathematics
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• v.20 no.2
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• pp.1-18
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• 2007

In the middle of 19th century, Chosun mathematicians Nam Byung Gil(南秉吉) and Lee Sang Hyuk(李尙爀) studied mathematical structures developed in Song(宋) and Yuan(元) eras on top of their early studies on Jiu zhang suan shu(九章算術) and Shu li jing yun(數理精蘊). Their studies gave rise to a momentum for a prominent development of Chosun mathematics in the century. In this paper, we investigate Nam Byung Gil's JipGoYunDan(輯古演段) and MuIHae(無異解) and then study his theory of equations. Through a collaboration with Lee, Sang Hyuk, he consolidated the eastern and western structure of theory of equations.

• Ceramist
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• v.22 no.4
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• pp.350-356
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• 2019

Recently, transition metal dichalcogenide (TMDC) monolayers have been the subject of research exploring the physical phenomenon generated by low dimensionality and high symmetry. One of the keys to understanding new physical observations is the electronic band structure of 2D TMDCs. Angle-resolved photoelectron spectroscopy (ARPES) is, to this point, the best technique for obtaining information on the electronic structure of 2D TMDCs. However, through ARPES research, obtaining the long-range well-ordered single crystal samples always proves a challenging and obstacle presenting issue, which has been limiting towards measuring the electronic band structures of samples. This is particularly true in general 2D TMDCs cases. Here, we introduce the approach, with a mathematical framework, to overcome such ARPES limitations by employing the high level of symmetry of 2D TMDCs. Their high symmetry enables measurement of the clear and sharp electronic band dispersion, which is dominated by the band dispersion of single-crystal TMDCs along the two high symmetry directions Γ-K and Γ-M. In addition, we present two important studies and observations for the direct measuring of the exciton binding energy and charge transfer of 2D TMDCs, both being established by the above novel approach.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2192-2195
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• 2002

Even though, tanks are used at the many industry plants, it is very difficult to control the tank level without any overflow and shortage; moreover, cause of its complication of dynamics and nonlinearity, it's impossible to realize the accurate control using the mathematical model which can be applied to the various operation modes. However, the sliding mode controller(SMC) is known as having the robust variable structures for the nonlinear control systems with the parametric perturbations and with the sudden disturbances. It's difficult to find SMC's parameters, and SMC is bring chattering which injures actuator and increases error. In this paper, Genetic Aloglism based Fuzzy Sliding Mode Controller(GA-FSMC) for the precise control of the coupled tank level was proposed. Genetic Algolism and Fuzzy logic are adapted to find SMC's parameters and reduce the chattering. The simulation result is shown that the tank level could be satisfactorily controlled with less overshoot and steady-state error by the proposed GA-FSMC.

• Smart Structures and Systems
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• v.17 no.4
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• pp.611-629
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• 2016

This study presents a new approach of surrogate modeling for time-consuming finite element analysis. A surrogate model is widely used to reduce the computational cost under an iterative computational analysis. Although a variety of the methods have been widely investigated, there are still difficulties in surrogate modeling from a practical point of view: (1) How to derive optimal design of experiments (i.e., the number of training samples and their locations); and (2) diagnostics of the surrogate model. To overcome these difficulties, we propose a sequential surrogate modeling based on Gaussian process model (GPM) with self-adaptive sampling. The proposed approach not only enables further sampling to make GPM more accurate, but also evaluates the model adequacy within a sequential framework. The applicability of the proposed approach is first demonstrated by using mathematical test functions. Then, it is applied as a substitute of the iterative finite element analysis to Monte Carlo simulation for a response uncertainty analysis under correlated input uncertainties. In all numerical studies, it is successful to build GPM automatically with the minimal user intervention. The proposed approach can be customized for the various response surfaces and help a less experienced user save his/her efforts.

• Asia pacific journal of information systems
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• v.10 no.2
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• pp.51-69
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• 2000

Recently, as business problems become more complicated and require more precise quantitative results, large-scale model management systems are increasingly in demand for supporting the decision-making activities. In addition, as distributed computing over networks gains popularity, departmental computing systems are gradually adopted in an organization to facilitate collaboration of geographically dispersed multiple departments. In departmental collaborative model management systems, multiple departments share common models but approach them with different user-views depending on their departmental needs. Moreover, the shared models become evolved as their structures and the corresponding data sets change due to the dynamic nature of the operating environment and the inherent uncertainty associated with the problems. In such capacity, providing the multiple departmental users with synchronized and consistent views of the models is important to improve the overall productivity. In this paper, we propose a collaborative model management framework for coordinating model change and automatic user-view update in a departmental computing environment. To do so, we describes changes in the model and their effects occurred in departmental model management environments and identifies the constructs and processes for maintaining the consistency between a shared model and its departmental user-views. Especially, in this framework, generic model concept was adopted for accommodating diverse mathematical models in a uniform way in a modelbase and object-oriented database management systems(ODBMS) for combining the model management constructs and automatic user-view update mechanisms in a single formalism. A prototype object-oriented modeling environment was developed using an ODBMS called ObjectStore and $C^{++}$ programming language on Windows NT.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1783-1792
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• 2009

Although overlapping resonances have been studied extensively in conventional resonance theories, there have not been many studies on them in multichannel quantum defect theories (MQDT). In MQDT, overlapping resonances occur between the channels instead of states, which pose far greater difficulty. Their systematic treatment was obtained for cases involving degenerate closed channels by applying our previous theory, which decouples background scattering from the resonance scattering in the MQDT formulation. The use of mathematical theory on con-diagonalization and con-similarity was essential for handling the non-Hermitian symmetric complex matrix. Overlapping resonances in rare gas spectra of Ar, Kr and Xe were analyzed using this theory and the results were compared with the ones of the previous alternative parameterizations of MQDT which make the open-open part $K^{oo}$ and closed-closed part $K^{cc}$ of reactance submatrices zero. The comparison revealed that separation of background and resonance scatterings achieved in our formulation in a systematic way was not achieved in the representation of $K^{oo}\;=\;0\;and\;K^{cc}$ = 0 when overlapping resonances are present.