• 제어로봇시스템학회논문지
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• 제8권5호
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• pp.401-406
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• 2002

As product lifecycles become shorter, factories are pushed to develop small batches of many different products. The highly flexible control systems has become a necessity. The majority of existing automated industrial systems are controlled by programmable logic controllers(PLCs). In most cases, the control programs for PLCs are developed based on ladder diagrams(LDs). However, it is difficult to debug and maintain those LDs because the synthesis of LD itself mainly depends on the experience of the industrial engineer via trial-and-error methods. Hence, in this paper, we propose a discrete event model conversion algorithm for systematic analysis of LDs. The proposed discrete event model conversion algorithm is illustrated by an example of a conveyor system.

• Coupled systems mechanics
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• 제7권1호
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• pp.43-59
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• 2018

The presence of the pore fluid strongly influences the reponse of the soil subjected to external loading and in many cases increases the risk of final failure. In this paper, we propose the use of a discrete beam lattice model with the aim to investigate the coupling effects of the solid and fluid phase on the response and failure mechanisms in the saturated soil. The discrete cohesive link lattice model used in this paper, is based on inelastic Timoshenko beam finite elements with enhanced kinematics in axial and transverse direction. The coupling equations for the soil-pore fluid interaction are derived from Terzaghi's principle of effective stresses, Biot's porous media theory and Darcy's law for fluid flow through porous media. The application of the model in soil mechanics is illustrated through several numerical simulations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.352-355
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• 1995

In this paper, estimation error bounds of the optimal FIR (Finite Impulse Response) filter, which is proposed by Kwon et al.[1, 2], are presented in discrete-time systems with the model uncertainty. Performance bounds are here represented by the upper bounds on the difference of the estimation error covariances between the nominal and real values in case of the systems with the noise or model parameter uncertainty. The estimation error bounds of the discrete-time optimal FIR filter is compared with those of the Kalman filter via a numerical example applied to the simulation problem by Toda and Patel[3]. Simulation results show that the former has robuster performance than the latter.

• 한국멀티미디어학회논문지
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• 제21권1호
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• pp.61-68
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• 2018

In this paper, we present an effective encryption algorithm for 3D printing models in the frequency domain of discrete cosine transform to prevent illegal copying, access in the secured storage and transmission. Facet data of 3D printing model is extracted to construct a three by three matrix that is then transformed to the frequency domain of discrete cosine transform. The proposed algorithm is based on encrypting the DC coefficients of matrixes of facets in the frequency domain of discrete cosine transform in order to generate the encrypted 3D printing model. Experimental results verified that the proposed algorithm is very effective for 3D printing models. The entire 3D printing model is altered after the encryption process. The proposed algorithm is provide a better method and more security than previous methods.

• Advances in nano research
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• 제15권1호
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• pp.25-34
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• 2023

This paper investigates the dynamics and stability of steady states in a continuous and discrete-time single-mode laser system. By using an explicit criteria we explored the Neimark-Sacker bifurcation of the single mode continuous and discrete-time laser model at its positive equilibrium points. Moreover, we discussed the parametric conditions for the existence of period-doubling bifurcations at their positive steady states for the discrete time system. Both types of bifurcations are verified by the Lyapunov exponents, while the maximum Lyapunov ensures chaotic and complex behaviour. Furthermore, in a three-dimensional discrete-time laser model, we used a hybrid control method to control period-doubling and Neimark-Sacker bifurcation. To validate our theoretical discussion, we provide some numerical simulations.

• Journal of the Korean Data and Information Science Society
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• 제15권3호
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• pp.575-584
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• 2004

We propose a Bayesian model-based approach using a mixture of Dirichlet processes model with discrete wavelet transform, for curve clustering in the microarray data with time-course gene expressions.

• 터널과지하공간
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• 제11권2호
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• pp.156-166
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• 2001

균열암반에서의 지하수유동 모사를 위한 추계적 연속테 모델링 기법이 개발되었다. 추계적연속체 모델은 균열수의 제한을 가지는 개별균열연결망 모델의 단점을 극복할 수 있다. 뿐만 아니라 개별균열연결망 모델에서 가능한 확률론적 해석과 전도성이 큰 균열을 통한 지하수 유동을 근접하게 모사할 수 있는 장점을 가진다. 추계적연속체 모델은 개별균열연결망 모델에 근거하여 생성된다. 개별균열연결망 모델은 일정크기의 소블록으로 나누어지며 각 소블록 투수계수의 확률밀도함수와 베리오그램 함수로부터 추계적연속체 모델에서의 투수계수의 공간적 분포를 정의할 수 있다. 이 연구에서 추계적연속체 모델과 개별균열연결망 모델의 적합성을 보여 주기 위하여 수치실험을 통하여 지하수 유동 이동시간을 계산하고 상호 비교하였다. 그리고 추계적연속체 모델은 방사성폐기물 처분장의 확률론적 안전성 펑가를 위해 필요한 지하수 유동속도의 확률분포를 제공할 수 있는 모델임을 제시할 수 있었다.

• 한국농공학회논문집
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• 제51권3호
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• pp.45-52
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• 2009

Generally, structures are analyzed as continuum. However, sometimes it is more efficient to analyze structure as a discrete model rather than as a continuum model in case of the structure has complex shape or loading condition. This study, therefore, suggests an improved analysis discrete model, named Equivalent Truss Model (further as "ETM"), which can obtain similar results with analyzing continuums analysis. ETM adopts a lattice truss to compose the members of the model, and analyses the structures. As a consequence, the ETM produced the identical outcome with the continuums analysis in section force of different structures and loading conditions. Similar results have been shown in internal stress analysis as well. Make use of that ETM is discrete, fractural path of beam was analyzed by ETM and the result was reasonable.

• Computers and Concrete
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• 제5권4호
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• pp.329-342
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• 2008

A local behavior law, which includes elasticity, plasticity and damage, is developed in a three dimensional numerical model for concrete. The model is based on the Discrete Element Method (DEM)and the computational implementation has been carried out in the numerical Code YADE. This model was used to study the response of a concrete slab impacted by a rigid missile, and focuses on the extension of the compacted zone. To do so, the model was first used to simulate compression and hydrostatic tests. Once the local constitutive law parameters of the discrete element model were calibrated, the numerical model simulated the impact of a rigid missile used as a reference case to be compared to an experimental data set. From this reference case, simulations were carried out to show the importance of compaction during an impact and how it expands depending on the different impact conditions. Moreover, the numerical results were compared to empirical predictive formulae for penetration and perforation cases, demonstrating the importance of taking into account the local compaction process in the local interaction law between discrete elements.

• 전력전자학회논문지
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• 제10권3호
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• pp.219-225
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• 2005

본 논문에서는 평균전류모드제어를 이용하는 컨버터의 전류응답을 예측할 수 있는 새로운 이산시간 소신호 모델을 구한다. 평균전류모드제어는 최대전류모드제어와 달리 전류제어를 위해 복잡한 보상기 회로를 사용하므로 컨버터의 동작 특성 해석이 어렵다. 평균전류모드제어를 사용하는 컨버터의 소신호 전류응답을 예측하기 위해 샘플러모델을 제안하고, 이 모델로부터 새로운 이산시간 소신호 모델을 구한다. 제안된 방식은 기존 방식과 달리 복잡한 형태의 보상기를 사용하는 컨버터에도 적용 가능하다. 제안한 새로운 이산시간 소신호 모델을 이용한 예측 결과를 스위칭 모델 시뮬레이션 프로그램인 PSIM을 이용한 시뮬레이션 결과 및 실험결과와 비교하여 제안한 새로운 이산시간 소신호 모델의 우수성을 보인다.