• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1594-1599
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• 2008

Haptic rendering is a process that provides force feedback during interactions between a user and an object. This paper presents a haptic rendering technique for a telemanipulation system of deformable objects using image processing and physically based modeling techniques. The interaction forces between an instrument driven by a haptic device and a deformable object are inferred in real time based on a continuum mechanics model of the object, which consists of a boundary element model and ${\alpha}$ priori knowledge of the object's mechanical properties. Macro- and micro-scale experimental systems, equipped with a telemanipulation system and a commercial haptic display, were developed and tested using silicone (macro-scale) and zebrafish embryos (micro-scale). The experimental results showed the effectiveness of the algorithm in different scales: two experimental systems applied the same algorithm provided haptic feedback regardless of the system scale.

• Water Engineering Research
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• v.1 no.3
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• pp.243-256
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• 2000

This physically-based hydrologic model is developed to calculate the soil-moisture balance on paddy fields. This model consists of three modules; the first is the unsaturated module, the second is the rice evapotranspiration module with SPAC(soil-plant-atmospheric-continuum), and the third is the groundwater and open channel flows based upon the interrehtionship module. The model simulates the hydrlogical processes of infiltration, soil water storage, deep perocolation or echarge to the shallow water table, transpiration and evaporation from the soil surface and also the interrelationship of the groundwater and river flow exchange. To verify the applicability of the developed model, it was applied to the Kimjae Plains, located in the center of the Dongjin river basin in Korea, during the most serious drought season of 1994. The result shows that the estimated water net requirement was 757mm and the water deficit was about 5.9% in this area in 1994. This model can easily evaluate the irrigated water quantity and visualize the common crop demands and soil moisture conditions.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.3
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• pp.147-156
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• 2006

Physically-based simulation modeling is to simulate the real world by using physical laws such as Newton's second law of motion, while other modelings use only geometric Properties. In this paper, we present a real time simulation of stone skipping by using the physically-based modeling. We also describe interaction of a stone on the surface of water, and focus on calculating the path of the stone and the natural phenomena of water The path is decided by velocity of the stone and drag force from the water The motion is recalculated until the stone is immersing into the water surface. Our simulation provides a natural motion of stone skippings in real time. And the motion of stone skippings are generated by give interactive displays on the PC platforms. The techniques presented can easily be extended to simulate other interactive dynamics systems.

• Journal of Korea Multimedia Society
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• v.9 no.5
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• pp.554-563
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• 2006

We present a linear-time algorithm for treating collision response of articulated rigid bodies in physically based modeling. By utilizing the topology of articulated rigid bodies and the property of linear equations, our method can solve in linear time the system of linear equations that is crucial for treating collision response. We also present several new joint condition equations for articulated rigid bodies composed of various joints.

• Transactions of Materials Processing
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• v.22 no.8
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• pp.450-455
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• 2013

In the current study, a new dynamic recrystallization model for predicting high temperature flow stress is developed based on a physical model and the mean field theory. In the model, the grain aggregate is assumed as a representative volume element to describe dynamic recrystallization. The flow stress and microstructure during dynamic recrystallization were calculated using three sub-models for work hardening, for nucleation and for growth. In the case of work hardening, a single parameter dislocation density model was used to calculate change of dislocation density and stress in the grains. For modeling nucleation, the nucleation criterion developed was based on the grain boundary bulge mechanism and a constant nucleation rate was assumed. Conventional rate theory was used for describing growth. The flow stress behavior of pure copper was investigated using the model and compared with experimental findings. Simulated results by cellular automata were used for validating the model.

• Electronics and Telecommunications Trends
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• v.12 no.6 s.48
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• pp.24-38
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• 1997

본 기고에서는 멀티미디어 컨텐트에 등장하는 애니메이션 캐릭터를 개발하는 캐릭터 모델링 시스템의 기본적인 요구기능과 캐릭터 모델링 기법을 분석하고, 상용화된 모델링 시스템 및 라이브러리를 소개, 분석한다. 앞으로 설계되는 캐릭터 모델링 소프트웨어는 모델링 및 애니메이션 시스템을 통합한 환경에서 곡면기반의 기하 모델링 소프트웨어가 주류를 이룰 것으로 전망된다. 또한 캐릭터의 외피와 같이 유연하고 부드러운 물체를 표현하기 위하여 physically based modeling 기법과 음함수 곡면이 많이 사용될 것으로 판단된다.

• International Journal of CAD/CAM
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• v.9 no.1
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• pp.79-83
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• 2010

Tidal bore is a peculiar nature phenomenon which is caused by the lunar and solar gravitation. Based on the physical characters of tidal bores, in this paper we propose a novel method to model and render this phenomenon, especially the tidal waves in Qiantang estuary. According to Boltzmann equation for tidal waves, we solve it with the novel triangle mesh of Kinectic Flux Vector Splitting (KFVS) mode. Then a method combining a curve forecasting wave and particles model is proposed to render the dynamic scenes of overturning tidal waves. Finally, with some rendering technologies, various realistic tidal waves under diversified conditions is rendered in real time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.4
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• pp.416-422
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• 2019

This paper proposes a GPU-based modeling and rendering of 3D clouds using procedural functions. The formation of clouds is based on modified noise function made with fbm(Fractional Brownian Motion). Those noise values turn into densities of droplets of liquid water, which is a critical parameter for forming the three different types of clouds. At the rendering stage, the algorithm applies the ray marching technique to decide the colors of cloud using density values obtained from the noise function. In this process, all lighting attenuation and scattering are calculated by physically based manner. Once we have the clouds, they are blended on the sky, which is also rendered physically. We also make the clouds moving in the sky by the wind force. All algorithms are implemented and tested on GPU using GLSL.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.265-271
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• 1997

A bond graph modeling approach which is equivalent to a finite element method is formulated in the case of the piezoelectric thickness vibrator. This formulation suggests a new definition of the generalized displacements for a continuous system as well as the piezoelectric thickness vibrator. The newly defined coordinates are illustrated to be easily interpreted physically and easily used in analysis of the system performance. Compared to the Mason equivalent circuit model, the bond graph model offers the primary advantage of physical realizability. Compared to circuit models based on standard discrete electrical elements, the main advantage of the bond graph model is a greater physical accuracy because of the use of multiport energic elements. While results are presented here for the thickness vibrator, the modeling method presented is general in scope and can be applied to arbitrary physical systems.

• Korean Journal of Computational Design and Engineering
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• v.4 no.1
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• pp.12-18
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• 1999

A deformable non-Uniform Rational B-Spline (NURBS) based volume is programed for the force reflecting exoskeleton haptic device. In this work, a direct free form deformation (DFFD) technique is applied for the realistic manipulation. In order to implement the real-time deformation, a nodal mapping technique is used to connect points on the virtual object with the NURBS volume. This geometric modeling technique is ideally incorporated with the force reflecting haptic device as a virtual interface. The results in this work introduce details for the complete set-up for the realistic virtual clay modeling task with force feedback. The force reflecting exoskeleton haptic manipulator, coupled with a supporting PUMA 560 manipulator and the virtual clay model are integrated with the graphics display, and results show that the force feedback from the realistic physically based virtual environment can greately enhance the sense of immersion.