• 한국HCI학회:학술대회논문집
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• 2007.02c
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• pp.326-333
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• 2007

To simulate solid dynamics,a we must com-pute the mass, the center of mass, and the products of inertia about the axes of the body of interest. These mass property computations must be continuously re-peated for certain simulations with rigid bodies or as the shape of the body changes. We introduce a GPU-friendly algorithm to approximate the mass properties for an arbitrarily shaped body. Our algorithm converts the necessary volume integrals into surface integrals on a projected plane. It then maps the plane into a frame-buffer in order to perform the surface integrals rapidly on the GPU. To deal with non-convex shapes, we use a depth-peeling algorithm. Our approach is image-based; hence, it is not restricted by the mathematical or geometric representation of the body, which means that it can efficiently compute the mass properties of any object that can be rendered on the graphics hardware. We compare the speed and accuracy of our algorithm with an analytic algorithm, and demonstrate it in a hydrostatic buoyancy simulation for real-time applications, such as interactive games.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1661-1666
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• 2003

The purpose of this study is to develop the simplified model of the crankshaft in the large marine engine for dynamic analysis. Because the actual engine system is under complex dynamic loading condition and it has multi-cylinder, the dynamic analysis is purchased at a high computation cost. In spite of this burden, the dynamic analysis must be perfonned to assure structural integrity of operating marine engine. Therefore, simplification of the analytic model is necessary for dynamic analysis. Beam-mass model, which is generated with the section property method, is the model simplified effectively. Section property method can provide desired section information by optimization technique. By applying beam-mass model to the crankshaft in the large marine engine, the usefulness of the proposed method was proven.

• Preventive Nutrition and Food Science
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• v.8 no.4
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• pp.419-424
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• 2003

The physical properties of food playa significant role in the modeling and computation of the heat and mass transfers in basic food processing operations. With the advent of improved analytical techniques, statistical experiment design applications, computing ability and knowledge of the food physical properties of food, there have been significant advances in our ability to predict the impact of processing on the physical properties of food. This article briefly reviews our current ability to predict the influence of processing on the physical properties of food, such as water activity, moisture, color, and rheological characteristics.

• Journal of the Korea Computer Graphics Society
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• v.18 no.2
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• pp.55-62
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• 2012

This paper presents a new method to represent the secondary deformation effect using simple mass-spring simulation on the vertex shader of the GPU. For each skin vertex of a 3D character, a zero-length spring is connected to a virtual vertex that is to be rendered. When a skin vertex changes its position and velocity according to the character motion, the position of the corresponding virtual vertex is computed by mass-spring simulation in parallel on the GPU. The proposed method represents the secondary deformation effect very fast that shows the material property of a character skin during the animation. Applying the proposed technique dynamically can represent squash-and-stretch and follow-through effects which have been frequently shown in the traditional 2D animation, within a very small amount of additional computation. The proposed method is applicable to represent elastic skin deformation of a virtual character in an interactive animation environment such as games.

• Smart Structures and Systems
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• v.2 no.2
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• pp.127-140
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• 2006

In this study, a wavelet-based covariance-driven system identification technique is proposed for damage assessment of structures under ambient excitation. Assuming the ambient excitation to be a white-noise process, the covariance computation is shown to be able to separate the effect of random excitation from the response measurement. Wavelet transform (WT) is then used to convert the covariance response in the time domain to the WT magnitude plot in the time-scale plane. The wavelet coefficients along the curves where energy concentrated are extracted and used to estimate the modal properties of the structure. These modal property estimations lead to the calculation of the stiffness matrix when either the spectral density of the random loading or the mass matrix is given. The predicted stiffness matrix hence provides a direct assessment on the possible location and severity of damage which results in stiffness alteration. To demonstrate the proposed wavelet-based damage assessment technique, a numerical example on a 3 degree-of-freedom (DOF) system and an experimental study on a three-story building model, which are all under a broad-band excitation, are presented. Both numerical and experimental results illustrate that the proposed technique can provide an accurate assessment on the damage location. It is however noted that the assessment of damage severity is not as accurate, which might be due to the errors associated with the mode shape estimations as well as the assumption of proportional damping adopted in the formulation.

• Journal of the Korean association of regional geographers
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• v.4 no.1
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• pp.121-134
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• 1998

In this study, the satellite images and the GIS technique are used to select the basin characteristics parameters as the basis of water resources management of river basin. The study area is Geum-ho river basin and the hydrologic characteristics data are computed through the database of the basin characteristics parameters classified by subjects with 35 maps correspond to the study basin of 1:25,000 scale as the basic map. As the result, the drawing up of land use map through satellite image processing that provides the quantitative informations for the land is very efficient to analysis the extensive land use information of the basin, and exact analysis of mass surface data is possible and the feasibility of statistic computation between spatial subjects as it superpose on other subject map is ascertained. It is thought also that the analysis of the basin characteristics data can be utilized very effectively for the basin management and the analysis of basin surface area, once it is expressed numerically for database, since the superposition analysis with different subject map and the correlative analysis with the property data are possible although the tracing process of each subject in the basic map is not efficient. Especially, modification and renewal of the data for the change of land surface become easy, therefore more rapid and exact selection of the basin characteristics data and the construction of more efficient basin management plan are possible.