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

• Structural Engineering and Mechanics
• /
• v.61 no.1
• /
• pp.65-76
• /
• 2017

Prediction of the characteristics of both in-plane and out-of-plane elastic waves within conducting nanoplates in the presence of bidirectionally in-plane magnetic fields is of interest. Using Lorentz's formulas and nonlocal continuum theory of Eringen, the nonlocal elastic version of the equations of motion is obtained. The frequencies as well as the corresponding phase and group velocities pertinent to the in-plane and out-of-plane waves are analytically evaluated. The roles of the strength of in-plane magnetic field, wavenumber, wave direction, nanoplate's thickness, and small-scale parameter on characteristics of waves are discussed. The obtained results show that the in-plane frequencies commonly grow with the in-plane magnetic field. However, the transmissibility of the out-of-plane waves rigorously depends on the magnetic field strength, direction of the propagated transverse waves, small-scale parameter, and thickness of the nanoplate. The criterion for safe transferring of the out-of-plane waves through the conducting nanoplate immersed in a bidirectional magnetic field is also explained and discussed.

• International Journal of Aerospace System Engineering
• /
• v.2 no.2
• /
• pp.19-23
• /
• 2015

This work deals with the study of buckling and post buckling characteristics of laminated composite plates with and without localized regions of damage. The need of a detailed study on Finite Element Analysis of buckling and post buckling of laminated composite structures considering various aspects enhances the interest among researchers. Mathematical formulation is developed for damaged composite plates using a finite element technique based on Inverse Hyperbolic Shear Deformation Theory. This theory satisfies zero transverse shear stresses conditions at the top and bottom surfaces of the plate and provides a non-linear transverse shear stress distribution. Damage modeling is done using an anisotropic damage formulation, which is based on the concept of stiffness change. The structural elements are subjected to in-plane loading. The computer program is developed in MATLAB environment. The numerical results are presented after through validation of developed finite element code. The effect of damage on buckling and post buckling has been carried out for various parameters such as amount of percentage of damaged area, damage intensity, etc. The results show that the presence of internal flaws will significantly affect the buckling characteristics of laminated composite plates. The outcomes and remarks from this work will assist to address some key issues concerning composite structures.

• Nuclear Engineering and Technology
• /
• v.50 no.3
• /
• pp.453-461
• /
• 2018

Shaft stations of underground uranium mines in China are not only utilized as waiting space for loaded mine-cars queuing to be hoisted but also as the principal channel for fresh air taken to working places. Therefore, assessment of how mine-car queuing processes affect shaft station radon concentration was carried out. Queuing network of mine-cars has been analyzed in an underground uranium mine, located in Quzhou, Zhejiang province of Eastern China. On the basis of mathematical analysis of the queue network, a MATLAB-based quasi-random number generating program utilizing Monte-Carlo methods was worked out. Extensive simulations were then implemented via MATALB operating on a DELL PC. Thereafter, theoretical calculations and field measurements of shaft station radon concentrations for several working conditions were performed. The queuing performance measures of interest, like average queuing length and waiting time, were found to be significantly affected by the utilization rate (positively correlated). However, even with respect to the "worst case", the shaft station radon concentration was always lower than $200Bq/m^3$. The model predictions were compared with the measuring results, and a satisfactory agreement was noted. Under current working conditions, queuing-induced variations of shaft station radon concentration of the study mine are not remarkable.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.10a
• /
• pp.132-138
• /
• 2013

Natural gas as a clean fuel of the world demand for the trend is gradually increasing demand for clean energy in the country and there is growing interest. Therefore, LNG storage tanks and related facilities in the country of the importance of leading a community-based facility has emerged. So common sense that an earthquake with a seismic isolation device LNG storage tank similar to the actual behavior of the analytical model which can describe the development and construction of storage tanks to enhance the safety and economic design techniques need to be developed. In this study, a base isolation system, seismic analysis procedure of LNG storage tanks, and Triple-FPB developed a mathematical model of the present crystallized and complexity factors to the sum over histories model simplifies the complex behavior of the LNG storage tank with base isolation system how to interpret the seismic isolation is proposed.

• Structural Engineering and Mechanics
• /
• v.20 no.1
• /
• pp.1-20
• /
• 2005

The present paper deals with the seismic response analysis and the evaluation of most likely failure modes for a water storage structure. For the stress analysis, a 3-D mathematical model has been adopted to represent the structure appropriately. The structure has been analyzed for both static and seismic loads. Seismic analysis has been carried out considering the hydrodynamic effects of the contained water. Based on the stress analyses results, the most likely failure modes viz. tensile cracking and compressive crushing of concrete for the various structural elements; caused by the seismic event have been investigated. Further an attempt has also been made to quantify the initial leakage rate and average emptying time for the structure during seismic event after evaluating the various crack parameters viz. crack-width and crack-spacing at the locations of interest. The results are presented with reference to peak ground acceleration (PGA) of the seismic event. It has been observed that, an increase in PGA would result in significant increase in stresses and crack width in the various structural members. Significant increase in initial leakage rate and decrease in average emptying time for the structure has also been observed with the increase in PGA.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.21 no.5
• /
• pp.189-195
• /
• 2021

This paper discusses choice of loans problem(CLP) that is to minimize annual payment from which bank's borrows in multi-banks multi-nations with distinct interests. For the CLP, there is impossible to obtain the optimal solution actually without the help of mathematical software package as linear programming(LP). This paper applies the method used in transportation problem(TP) that finds initial feasible solution with selects minimum interest first, least cost method(LCM), to CLP. Result of experiment, the proposed algorithm can be obtains the optimal solution with at most two exchange optimization for LCM's initial feasible solution.

• Safety and Health at Work
• /
• v.12 no.2
• /
• pp.154-166
• /
• 2021

Background: Occupational health and safety (OHS) is a significant interest of all governments to prevent workplace hazards. Although appropriate legislation and regulations are essentials for the protection of workers, they are solely not enough. Application of them in practice should be secured by an efficient inspection system. Fundamental components of an inspection system are inspectors and their audit tasks. Maintaining the fair balanced task assignment among inspectors strictly enhances the efficiency of the overall system. Methods: This study proposes a two-phased goal programming approach for OHS inspectors' task assignments and presents a case study. Results: The solution approach gives the balanced assignment of inspectors to the workplaces in different cities of the country in the planning period. The obtained schedule takes into account the distances covered by the work places and the number of the workplaces' employees to be audited and pays attention to the human factors by considering the preferences of the inspectors. The comparisons between the obtained optimal schedule and the implemented one that is produced manually show that the approach not only maintains the technical requirements of the problem, but also provides social and physical balance to the task assignment. Conclusion: Both the approach and the application study are expected to offer fruitful inspirations in the area of safety management and policy and they provide a good guide for social policy and organizational aspects in the field of OHS inspectors' task assignment.

• Communications of Mathematical Education
• /
• v.30 no.3
• /
• pp.393-418
• /
• 2016

Theory and fundamentals of mathematics consist mostly of proposition form. Activities by research of the proposition which leads to determine the true or false, justify the true propositions and refute with counterexample improve logical reasoning skills of students in emphases on mathematics education. Also, utilizing of counterexamples in school mathematics combines mathematical knowledge through the process of finding a counterexample, help the concept study and increase the critical thinking. These effects have been found through previous research. But many studies say that the learners have difficulty in generating counterexamples for false propositions and materials have not been developed a lot for the counterexample utilizing that can be applied in schools. So, this study analyzed the current textbook and examined the use of counterexamples and developed educational materials for counterexamples that can be applied at schools. That materials consisted of making true & false propositions and students was divided into three groups of academic achievement level. And then this study looked at the change of the students' thinking after counterexample classes. As a study result, in all three groups was showed a positive change in the cognitive domain and affective domain. Especially, in top-level group was mainly showed a positive change in the cognitive domain, in upper-middle group was mainly showed in the cognitive and the affective domain, in the sub-group was mainly found a positive change in the affective domain. Also in this study shows that the class that makes true or false propositions in education of utilizing counterexample, made students understand a given proposition, pay attention to easily overlooked condition, carefully observe symbol sign and change thinking of cognitive domain helping concept learning regardless of academic achievement levels of learners. Also, that class gave positive affect to affective domain that increase interest in the proposition and gain confidence about proposition.

• School Mathematics
• /
• v.13 no.2
• /
• pp.307-321
• /
• 2011

Recognizing the importance of affective factors in mathematical learning and achievement, international comparative assessment as PISA and TIMSS survey affective achievement as well as scholastic achievement. On the affective survey those items of PISA are categorized by 5 factors ; interest of mathematics, instrumental motivation, Mathematics self-efficacy, mathematics anxiety, mathematics self-concept) and those of TIMSS are categorized by 3 factors; Positive affect toward mathematics (PATM), Students' Self-Confidence in Learning Mathematics(SCM), and Students' Valuing Mathematics(SVM). In this study we carried out Exploratory Factor Analysis, Confirmatory Factor Analysis and Measurement Equivalence/Invariance to find whether the constructs are well defined and divided. As a result of our analysis, some factors were overlapped in PISA whereas the items of TIMSS were categorized as intended in TIMSS study. Based on these results, it is confirmed that the questionnaire items need to be developed to understand our students affective characteristics. Also, how questionnaire of large-scaled international assessment can give implication to the development of the questionnaire of Korean specific.