• Journal of the Korea Society for Simulation
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• v.22 no.4
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• pp.67-82
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• 2013

This paper presents multi-fidelity modeling and simulation (M&S) methodology to enhance simulation performance of engineering-level defense models. In this approach, a set of models with varying degrees of fidelity is exercised to reduce computational expense maintaining a similar level of system effectiveness. For multi-fidelity M&S principles, this paper defines model fidelity from two perspectives (i.e., model behavior and execution), and suggests the Fidelity Change Point (FCP) to specify the fidelity conversion. With these concepts, this paper centers on three ideas: 1) two models' structure which are the Behavioral-Fidelity Interchangeable Model (B-FIM) and the Executional-Fidelity Interchangeable Model (E-FIM), 2) modeling formalism, and 3) a simulation algorithm to support them. From an abstract case study regarding a target tracking scenario with the utilization of the proposed method, we can gain interesting experimental results regarding the enhancement of simulation performance. Finally, we expect that this work will serve various M&S-based analysis areas for enhancing simulation performance.

• Journal of Korea Multimedia Society
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• v.23 no.10
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• pp.1270-1285
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• 2020

As a representative concept of the fourth industrial revolution era where everything is digitized, digital twin means analyzing and optimizing a complex system using a simulation model synchronized with the system. In this paper, we propose a digital twin simulation model for the efficient operation of urban railways in Busan. Due to the geopolitical nature of Busan, where there are many mountains and narrow roads, the railways are more useful than other public transportation. However, this inversely results in a high level of congestion, which is an inconvenience to citizens and may be fatal to the spread of the virus, such as COVID19. Considering these characteristics, the proposed model analyzes the congestion level of the railways in Busan. The model is developed based on a mathematical formalism called discrete-event system specification and deduces the congestion level and the average waiting time of passengers depending on the train schedule. In addition, a new schedule to reduce the congestion level is derived through particle swarm optimization, which helps the efficient operation of the railways. Although the model is developed for the railways in Busan, it can also be used for railways in other cities where a high level of congestion is a problem.

• Journal of architectural history
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• v.14 no.3 s.43
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• pp.103-118
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• 2005

This study is about the meaning of wooden brackets that are distinctive elements of wooden architecture in Korea, Japan, and China. Existing studies about wooden brackets have been limited to the boundary of formalism, so the object of this study is to make a breakthrough in the field of those studies. The Wooden brackets in this study are considered to be decorative elements, and the principles of their design are examined. The specific subject of the study is wooden architecture with Jusimpo-styled brackets that have brackets only on pillars. The definition of Jusimpo is reexamined first, and ChulMok-Ikkong which has not been regarded as a Jusimpo-styled wooden bracket is interpreted as Jusimpo-styled one in this study. Categorized into three types, Jusimpo is examined how it is expressed according to the type of the roof in a building. In view of the results, the wooden bracket system is an effective technique to express the formality, and two designing principles can be seen in Jusimpo; one that wooden brackets observed externally are standardized and regarded as the same ones, and the other that the style of wooden brackets used in the most formal building is Yi-ChulMok. These designing principles mean that the carpenter who was in charge of building the architecture had certain principles when expressing wooden brackets as well as the roofs according to the class of the architecture. In addition, although the styles of wooden brackets that were used in the most formal architecture during the Chosun period were mostly Dapo, Jusimpo in the form of Yi-ChulMok was also adopted in some temples depending on their scale, and that means Jusimpo-styled wooden brackets were never considered to be inferior to Dapo-styled ones. And this point leaves the argument that the reexamination of Jusimpo-styled wooden brackets which have been regarded as the style used in the attached building or small structures since the Choun dynasty should be conducted.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.5 s.311
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• pp.10-18
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• 2006

We propose a new approach to compute possible acceleration boundary, so is called dynamic manipulability, for multiple robotic systems with frictional contacts between robot end-effectors and object. As the frictional contact condition which requires each contact force to lie within a friction cone is based on the nonlinear inequality formalism is not easy to handle the constraint in manipulability analysis. To include the frictional contact condition into the conventional manipulability analysis we approximate the friction cone to a pyramid which is described by linear inequality constraints. And then achievable acceleration boundaries of manipulated object are calculated conventional linear programming technique under constraints for torque capability of each robot and the approximated contact condition. With the proposed method we find some solution to which conventional approaches did not reach. Also, case studies are Presented to illustrate the correctness of the proposed approach for two robot systems of simple planar robots and PUMA560 robots.

• Korea-Australia Rheology Journal
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• v.15 no.3
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• pp.131-150
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• 2003

A new numerical algorithm of finite element methods is presented to solve high Deborah number flow problems with geometric singularities. The steady inertialess planar 4 : 1 contraction flow is chosen for its test. As a viscoelastic constitutive equation, we have applied the globally stable (dissipative and Hadamard stable) Leonov model that can also properly accommodate important nonlinear viscoelastic phenomena. The streamline upwinding method with discrete elastic-viscous stress splitting is incorporated. New interpolation functions classified as rational interpolation, an alternative formalism to enhance numerical convergence at high Deborah number, are implemented not for the whole set of finite elements but for a few elements attached to the entrance comer, where stress singularity seems to exist. The rational interpolation scheme contains one arbitrary parameter b that controls the singular behavior of the rational functions, and its value is specified to yield the best stabilization effect. The new interpolation method raises the limit of Deborah number by 2∼5 times. Therefore on average, we can obtain convergent solution up to the Deborah number of 200 for which the comer vortex size reaches 1.6 times of the half width of the upstream reservoir. Examining spatial violation of the positive definiteness of the elastic strain tensor, we conjecture that the stabilization effect results from the peculiar behavior of rational functions identified as steep gradient on one domain boundary and linear slope on the other. Whereas the rational interpolation of both elastic strain and velocity distorts solutions significantly, it is shown that the variation of solutions incurred by rational interpolation only of the elastic strain is almost negligible. It is also verified that the rational interpolation deteriorates speed of convergence with respect to mesh refinement.

• Korean Institute of Interior Design Journal
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• v.16 no.2 s.61
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• pp.79-86
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• 2007

The recent works of architecture and interior design take on too various aspects to be classified as a trend or tendency. Many subjects, seeking the superiority between form and function in space which was the issue of Modernism, got to face the works which transcend the limitation of architecture due to the development of a variety of media and technology these days. In result, we could see the works which are to be Included into the category of art rather than architecture. This study starts from the thought that the common aspects of these works are based on the strangeness to pursue uniqueness, peculiarities or novelty. 'The subject of this study, $'D\acute{e}paysement'$, creates a new relation, disconnected from customs, to an architecture which became familiar through defragment, fixation and abstraction by the habitual relation and makes it reborn as an architecture which gives us a fantasy and a pleasure, by converting into the shape and image which are different from its original shape when a stimulus is given to an architecture. This study starts from the artistic aspect which has a close correlation with the architecture. The subject, $'D\acute{e}paysement'$ could be historically considered in two aspects - $D\acute{e}paysement$ of Surrealism which developed in paintings and Defamiliarization of Russian Formalism in the area of literature. This study is carried in a category of $D\acute{e}paysement$, focusing on the visual aspect of the architecture. This study is composed as follows: In chapter 2, a theoretical research is performed according to the definition and meaning of the $D\acute{e}paysement$ expression techniques, its origination and evolution, and type classification by the features of expression techniques in the era of Surrealism when $D\acute{e}paysement$ developed most vigorously in the area of art. In chapter 3, the system which formalizes the expression method of the techniques is presented, focusing on the case analysis of the artistic works according to the types of $D\acute{e}paysement$. In chapter 4, the application of the expression techniques of $D\acute{e}paysement$ is discussed by conducting cases analysis of the modern interior design.

• Korean Institute of Interior Design Journal
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• v.18 no.5
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• pp.59-70
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• 2009

Since the emergence of a philosophical theory called deconstructivism, intertextuality has been promote the hybrid phenomenon amongst other jenres in arts. Various research efforts in intertextuality, however, have been more focused on the fields of literature and philosophy, rather than of architecture. This study aims to clarify the intertextuality between architectural design, music and literature as the following analysis of James Joyce's Finnegan's Wake, John Cage's music and Bernard Tschumi's early works. Joyce's Garden of Bernard Tschumi's project and some of John Cage's music works had borrowed from Finnegan's Wake, a novel James Joyce. Hence, the commonality between Bernard Tschumi and John Cage can naturally be related through Finnegan's Wake. Also, Finnegan's Wake had been contextualized by Jacques Derrida before it was used as a mediation by Bernard Tschumi. In this viewpoint, the paper will be able to identify the possibility of intertextuality between musical text and architectural one with a medium of literature. Major findings of the study are as follows: First, Finnegan's Wake played a guiding role to deconstruct the existing formalism and to construct a new concept in John Cage's music and Bernard Tschumi's architecture. Second, John Cage's music and Bernard Tschumi's works are included commonness with indeterminacy concepts. Third, the both artists share a drawing concept as found in John Cage's graphic notation of the 1950s and Bernard Tschumi's early architecture where grids, dots, and curves are used in common. As s result, intertextuality could be possible to make sure between others. Like this interdisciplinary research of relationships among different fields will be of great help in constructing creative design methods in architecture. With continuous research attempts, it is hopeful to intertextualize architectural texts with related art fields.

• Journal of Korea Multimedia Society
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• v.23 no.6
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• pp.772-783
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• 2020

Tsunami is a frightful natural disaster that causes severe damages worldwide. To minimize the damage, South Korea has built a tsunami warning system and designated evacuation sites in the east and south coasts. However, such countermeasures have not been verified whether they are adequate to minimize casualties since tsunami rarely occurs in South Korea. Recently, due to increasing earthquakes in the west coast of Japan, the likelihood of South Korea entering the damage area of tsunami rises; thus, in this paper, we develops a simulator based on Unity game engine to simulate the evacuation from tsunami. In order to increase the fidelity of the simulation results, the simulator applies a tsunami simulation model that analyzes coastal inundation based on cellular automata. In addition, the objects included in tsunami evacuation, such as humans, are modeled as an agent model that determines the situation and acts itself, based on the discrete-event system specification (DEVS), a mathematical formalism for describing a discrete event system. The tsunami simulation model and agent models are integrated and visualized in the simulator using Unity game engine. As an example of the use of this simulator, we verify the existing tsunami evacuation site in Gwangalli Beach in Busan and suggest the optimal alternative site minimizing casualties.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.115-122
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• 2004

Software system modeling has a goal for finding and solving system's problems by describing and analyzing system model in formal notations. Petri nets, as graphical formalism, have been used in describing and analyzing the software systems such as parallel systems, real-time system, and protocols. In the analysis of Petri nets, general system properties such as deadlock and liveness are analyzed by the reachability analysis. On the other side, specific properties such as functional requirements and constraints are checked by model-checking. However, since these analysis methods are based on enumeration of ail possible states, there nay be state explosion problem, which means that system states exponentially increase as the size of system is larger. In this paper, we propose a new method for mechanically checking system properties with avoiding state explosion problem. At first, system properties are described in property nets then the system model and the property net are composed and analyzed. In the compositional analysis, system parts irrelevant to the specific property are reduced to minimize the analysis domain of the system. And it is possible to mechanically check whether a specific property is satisfied or not.

• Journal of KIISE:Software and Applications
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• v.28 no.9
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• pp.681-687
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• 2001

In order to raise a class discrimination power by combining multiple classifiers under the Bayesian decision theory, the upper bound of a Bayes error rate bounded by the conditional entropy of a class variable and decision variables obtained from training data samples should be minimized. Wang and Wong proposed a tree dependence first-order approximation scheme of a high order probability distribution composed of the class and multiple feature pattern variables for minimizing the upper bound of the Bayes error rate. This paper presents an extended high order product approximation scheme dealing with higher order dependency more than the first-order tree dependence, based on the minimization of the upper bound of the Bayes error rate. Multiple recognizers for unconstrained handwritten numerals from CENPARMI were combined by the proposed approximation scheme using the Bayesian formalism, and the high recognition rates were obtained by them.