• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.18 no.1
• /
• pp.149-159
• /
• 2008

In this paper, we propose a blind watermarking algorithm of 3d mesh model using spherical parameterization. Spherical parameterization is a useful method which is applicable to 3D data processing. Especially, orthogonal coordinate can not analyse the feature of the vertex coordination of the 3D mesh model, but this is possible to analyse and process. In this paper, the centroid center of the 3D model was set to the origin of the spherical coordinate, the orthogonal coordinate system was transformed to the spherical coordinate system, and then the spherical parameterization was applied. The watermark was embedded via addition/modification of the vertex after the feature analysis of the geometrical information and topological information. This algorithm is robust against to the typical geometrical attacks such as translation, scaling and rotation. It is also robust to the mesh reordering, file format change, mesh simplification, and smoothing. In this case, the this algorithm can extract the watermark information about $90{\sim}98%$ from the attacked model. This means it can be applicable to the game, virtual reality and rapid prototyping fields.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.3
• /
• pp.54-62
• /
• 2017

When gears mesh, shock and noise are produced as results of tooth error and tooth deformation under load. Transmission error (TE) is the most important cause of gear noise and vibration because TEs affect the changes of the force and the speed of gears. Gear tooth modification research plays a positive role in reducing TE and improving the design level and transmission performance of transmission systems. In high-precision manufacturing gear, gear tooth modification is also commonly used to reduce noise in practical applications. In order to study the accuracy of gear transmission, some empirical gear profile micro-modifications are introduced, and a helical gear pair is modeled and analyzed in RomaxDesigner software to investigate the utility of these modification methods. Some of these will be selected as experimental proposals for gear pairs, and these manufactured gears will be tested and compared in a semi-anechoic room later. The final purpose of this study is to find reasonable and convenient empirical formulae to facilitate improved gear production.

• The Journal of the Korea Contents Association
• /
• v.7 no.6
• /
• pp.52-59
• /
• 2007

This paper presents a greedy method for user-steered mesh segmentation, which is based on the merging priority metric defined for representing the geometric properties of meaningful parts. The priority metric is a weighted function composed of five geometric parameters: distribution of Gaussian map, boundary path concavity, boundary path length, cardinality, and segmentation resolution. This scheme can be extended without any modification only by defining more geometric parameters and adding them. Our experimental results show that the shapes of segmented parts can be controlled by setting up the weight values of geometric parameters.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.10a
• /
• pp.338-343
• /
• 2009

In this paper, Verification of the qualitatively identical relationships existing between simulation data and experimental results allowed for a new analysis procedure of a planetary gear set -- in an automatic transmission -- to be conducted. Tooth profiles were found to be crucial to the gear mesh forces of the planetary gear set. Based on Kahraman's Model[8], dynamic resonances of the planetary gear set were found to be out of operating range. Most importantly, a 2DPLANETARY FEM program, an innovative design tool for planetary gear sets, was utilized.

• Proceedings of the KSME Conference
• /
• 2001.06c
• /
• pp.269-274
• /
• 2001

In order to reduce trial-and-errors in the die design and production, CAE systems for analysis of stamping tools have been introduced at the initial design stage recently. For optimal design, the CAE engineers may need to correct the meshes generated by automatic mesh generation programs. However, they may need help of CAD engineers as they are usually not skilled in manipulation of CAD systems. In order to get around these problems, automatic shell mesh modification method is proposed, which utilizes existing CAD/CAE package (in this study, I-DEAS) without user interaction. The developed method and optimization techniques are applied to a stamping die rounding optimization problem. The optimization results show that the manpower and the time required at virtual tryout can be reduced by using the developed systems.

• Nuclear Engineering and Technology
• /
• v.52 no.3
• /
• pp.477-484
• /
• 2020

The control rod drive mechanism needs to be debugged after reactor fresh fuel loading. It is of great importance to monitor the subcriticality of this process accurately. A modified method was applied to the subcriticality monitoring process, in which only a single control rod cluster was fully withdrawn from the core. In order to correct the error in the results obtained by Neutron Source Multiplication Method, which is based on one point reactor model, Monte Carlo neutron transport code was employed to calculate the fission neutron distribution, the iterated fission probability and the neutron flux in the neutron detector. This article analyzed the effect of a coarse mesh and a fine mesh to tally fission neutron distributions, the iterated fission probability distributions and to calculate correction factors. The subcriticality before and after modification is compared with the subcriticality calculated by MCNP code. The modified results turn out to be closer to calculation. It's feasible to implement the modified NSM method in large local reactivity addition process using Monte Carlo code based on 3D model.

• Proceedings of the KIEE Conference
• /
• 2001.07a
• /
• pp.368-370
• /
• 2001

There are various shapes such as square, rectangular, L, and T type in the grounding systems of substations. IEEE St-d suggests the formula considering the characteristics of the various grounding systems but the final value can not be taken, and them the analysis of complicated computer program for obtaining the more accurate value is needed. In his paper, by using CDEGS(Current, Distribution, Electromagnetic and Soil Structure Analysis) the estimated functions derives form the modification coefficient for each of various types above mentioned. The mesh voltage expected can be obtained without the conventional expensive program using compensating methods that multiply IEEE formula by the estimated function.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2001.10a
• /
• pp.19-26
• /
• 2001

Previously, an improved crack analysis technique based on Element-Free Galerkin Method (EFGM) which includes a discontinuity function and a singular basis function was presented. The technique needs neither addition of nodes nor modification of the model, but it shows some dependency on the formulation and modeling parameters such as the class of weight function, the size of compact support, dilation parameter and the range controlled by the singular basis function. For those parameters, a parametric study was performed on the calculation of a discrete error and then, a guideline for the choice of adequate parameters in the technique was proposed.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.3
• /
• pp.242-248
• /
• 2010

In this paper, Verification of the qualitatively identical relationships existing between simulation data and experimental results allowed for a new analysis procedure of a planetary gear set -- in an automatic transmission -- to be conducted. Tooth profiles were found to be crucial to the gear mesh forces of the planetary gear set. Based on Kahraman's Model, dynamic resonances of the planetary gear set were found to be out of operating range. Most importantly, a 2DPLANETARY FEM program, an innovative design tool for planetary gear sets, was utilized.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.8
• /
• pp.3625-3630
• /
• 2013

The modularization accomplished a big contribution in cost down and assembly-time shortening and the quality increase. But few improvements were made to this design largely due to the inflexibility of steel. In recent years, door modules made of PP-LFT material is manufactured using injection molding method. As a result, the plastic door modules allow more flexibility of door shape and become lighter. Warpage is generally large in the molded plastic door carrier plate due to the limitation of gate location and the fiber orientation. So after a few test injection the mold compensation processing for the improvement of an assembly characteristic. This research was performed to determine the factors that contribute to warpage for a injection-molded door carrier plate and presented differences in three mesh types of meshing method and its results. as a result we can improve process of tooling modification can reduce process of trial and error.