• Title/Summary/Keyword: mathematical objects

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A Three-dimensional Biomechanical Model for Numerical Simulation of Dynamic Pressure Functional Performances of Graduated Compression Stocking (GCS)

  • Liu, Rong;Kwok, Yi-Lin;Li, Yi;Lao, Terence-T;Zhang, Xin;Dai, Xiao-Qun
    • Fibers and Polymers
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    • v.7 no.4
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    • pp.389-397
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    • 2006
  • The beneficial effects of graduated compression stockings (GCS) in prophylaxis and treatment of venous disorders of human lower extremity have been recognized. However, their pressure functional performances are variable and unstable in practical applications, and the exact mechanisms of action remain controversial. Direct surface pressure measurements and indirect material properties testing are not enough for fully understanding the interaction between stocking and leg. A three dimensional (3D) biomechanical mathematical model for numerically simulating the interaction between leg and GCS in dynamic wear was developed based on the actual geometry of the female leg obtained from 3D reconstruction of MR images and the real size and mechanical properties of the compression stocking prototype. The biomechanical solid leg model consists of bones and soft tissues, and an orthotropic shell model is built for the stocking hose. The dynamic putting-on process is simulated by defining the contact of finite relative sliding between the two objects. The surface pressure magnitude and distribution along the different height levels of the leg and stress profiles of stockings were simulated. As well, their dynamic alterations with time processing were quantitatively analyzed. Through validation, the simulated results showed a reasonable agreement with the experimental measurements, and the simulated pressure gradient distribution from the ankle to the thigh (100:67:30) accorded with the advised criterion by the European committee for standardization. The developed model can be used to predict and visualize the dynamic pressure and stress performances exerted by compression stocking in wear, and to optimize the material mechanical properties in stocking design, thus, helping us understand mechanisms of compression action and improving medical functions of GCS.

A Unity-based Simulator for Tsunami Evacuation with DEVS Agent Model and Cellular Automata (DEVS 에이전트 모델과 셀 오토마타를 사용한 유니티엔진 기반의 지진해일 대피 시뮬레이터 개발)

  • Lee, Dong Hun;Kim, Dong Min;Joo, Jun Mo;Joo, Jae Woo;Choi, Seon Han
    • Journal of Korea Multimedia Society
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    • v.23 no.6
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    • pp.772-783
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    • 2020
  • Tsunami is a frightful natural disaster that causes severe damages worldwide. To minimize the damage, South Korea has built a tsunami warning system and designated evacuation sites in the east and south coasts. However, such countermeasures have not been verified whether they are adequate to minimize casualties since tsunami rarely occurs in South Korea. Recently, due to increasing earthquakes in the west coast of Japan, the likelihood of South Korea entering the damage area of tsunami rises; thus, in this paper, we develops a simulator based on Unity game engine to simulate the evacuation from tsunami. In order to increase the fidelity of the simulation results, the simulator applies a tsunami simulation model that analyzes coastal inundation based on cellular automata. In addition, the objects included in tsunami evacuation, such as humans, are modeled as an agent model that determines the situation and acts itself, based on the discrete-event system specification (DEVS), a mathematical formalism for describing a discrete event system. The tsunami simulation model and agent models are integrated and visualized in the simulator using Unity game engine. As an example of the use of this simulator, we verify the existing tsunami evacuation site in Gwangalli Beach in Busan and suggest the optimal alternative site minimizing casualties.

Determination of Air Fuel Ratio according to Fuel Composition (I) -Eltinge Chart as a Reference Exhaust Composition- (연료 조성에 따른 공연비 산정 (I) -기준 배기 조성으로서 Eltinge 차트-)

  • Ohm, In-Yong;Park, Chan-Jun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.11
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    • pp.1548-1562
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    • 2003
  • This paper is the first of several companion papers which compare the methods of Air-fuel ratio determination. There are many methods which calculate Air-Fuel ratio from exhaust emission. Most of them are based on the simple chemical equations, which use balance of atom, and the error of the calculation is negligible as far as the instrumentation accuracy is guaranteed. They assume homogeneous mixture and complete combustion to the extent of oxygen availability. Because of these simple assumptions, they cannot offer the information about the fuel distribution state and the malfunction of instrument. For these limitations, Eltinge offered new one based on stricter mathematical model. This result coincides with the others very well and gives more information about the mixture state and instrumentation. Consequently this might be a general solution for Air-fuel ratio determination and exhaust composition. The objects of the calculation, however, were not commercial fuels except gasoline and the compensation method of unburned hydrocarbon was not appropriate to recent analyzer. Moreover he did not consider the fuel which contains oxygen, such as methanol, ethanol and blend of gasoline-alcohol. In this paper, Eltinge chart is expanded to the arbitrary fuel composition as the reference exhaust compositions for the purpose of further discussions about Air-fuel ratio determination methods and the charts fur gasoline, diesel, methanol, M85, liquefied petroleum gas(LPG), natural gas(NG), propane, butane are illustrated.

Analysis of the Error-Remedial Effect and Change of the Students' Misconception on the Learning of Linear Function (교수학적 처방에 따른 중학생들의 일차함수 오개념의 변화와 그 효과 분석)

  • 이종희;김부미
    • School Mathematics
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    • v.5 no.1
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    • pp.115-133
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    • 2003
  • Investigation of the students' mathematical misconceptions is very important for improvement in the school mathematics teach]ng and basis of curriculum. In this study, we categorize second-grade middle school students' misconceptions on the learning of linear function and make a comparative study of the error-remedial effect of students' collaborative learning vs explanatory leaching. We also investigate how to change and advance students' self-diagnosis and treatment of the milton ceptions through the collaborative learning about linear function. The result of the study shows that there are three main kinds of students' misconceptions in algebraic setting like this: (1) linear function misconception in relation with number concept, (2) misconception of the variables, (3) tenacity of specific perspective. Types of misconception in graphical setting are classified into misconception of graph Interpretation and prediction and that of variables as the objects of function. Two different remedies have a distinctive effect on treatment of the students' misconception under the each category. We also find that a misconception can develop into a correct conception as a result of interaction with other students.

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A Study on the Development of Instructional Materials for Systematic "Programming" by Realization of the Mathematical Program (수학 프로그램 구현을 통한 체계적 '프로그래밍' 교수 자료 개발에 관한 연구)

  • 박광철;김종훈
    • Journal of the Korea Computer Industry Society
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    • v.2 no.11
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    • pp.1407-1420
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    • 2001
  • There is an increasing concern about computer education with the age of knowledge-based society. The learning programming language is taking an important role of computer education. However, the special emphasis in learning programming language has been attached to memorizing the programming language by rote and learning computer programs. Therefore, those were not much useful tools to develope a logical intelligence of the meanings of programming language and the methods of realization. It is positively necessary to improve the programming education efficiently because of the objects of knowledge of computing and raising an efficiency of problem solving. Under the circumstances, this research is aimed at representing an useful education model through developing a mathmatical program into each part of the C programming language, which would be a new supplier of an basic insight into the programming language and techniques. Accordingly it is thought that the research material will be an useful model to increase interests and concerns as well as to raise an efficiency of problem solving or a logical intelligence going through the process of studying programming language.

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A study on object recognition using morphological shape decomposition

  • Ahn, Chang-Sun;Eum, Kyoung-Bae
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 1999.05a
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    • pp.185-191
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    • 1999
  • Mathematical morphology based on set theory has been applied to various areas in image processing. Pitas proposed a object recognition algorithm using Morphological Shape Decomposition(MSD), and a new representation scheme called Morphological Shape Representation(MSR). The Pitas's algorithm is a simple and adequate approach to recognize objects that are rotated 45 degree-units with respect to the model object. However, this recognition scheme fails in case of random rotation. This disadvantage may be compensated by defining small angle increments. However, this solution may greatly increase computational complexity because the smaller the step makes more number of rotations to be necessary. In this paper, we propose a new method for object recognition based on MSD. The first step of our method decomposes a binary shape into a union of simple binary shapes, and then a new tree structure is constructed which ran represent the relations of binary shapes in an object. finally, we obtain the feature informations invariant to the rotation, translation, and scaling from the tree and calculate matching scores using efficient matching measure. Because our method does not need to rotate the object to be tested, it could be more efficient than Pitas's one. MSR has an intricate structure so that it might be difficult to calculate matching scores even for a little complex object. But our tree has simpler structure than MSR, and easier to calculated the matchng score. We experimented 20 test images scaled, rotated, and translated versions of five kinds of automobile images. The simulation result using octagonal structure elements shows 95% correct recognition rate. The experimental results using approximated circular structure elements are examined. Also, the effect of noise on MSR scheme is considered.

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Constraint Relaxation using User Interaction in Reactive Scheduling Environment (동적 스케줄링 문제에서 사용자 상호작용을 이용한 제약조건 완화)

  • Lee, Hoon;Jung, Jong Jin;Jo, Geun Sik
    • Journal of Advanced Navigation Technology
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    • v.2 no.2
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    • pp.132-142
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    • 1998
  • In optical scanning holography, 3-D holographic information of an object is generated by 2-D active optical scanning. The optical scanning beam can be a time-dependent Gaussian apodized Fresnel zone plate. In this technique, the holographic information manifests itself as an electrical signal which can be sent to an electron-beam-addressed spatial light modulator for coherent image reconstruction. This technique can be applied to 3-D optical remote sensing especially for identifying flying objects. In this paper, we first briefly review optical scanning holography and analyze the resolution achievable with the system. We then present mathematical expression of real and virtual image which are responsible for holographic image reconstruction by using Gaussian beam profile.

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Robust Face and Facial Feature Tracking in Image Sequences (연속 영상에서 강인한 얼굴 및 얼굴 특징 추적)

  • Jang, Kyung-Shik;Lee, Chan-Hee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.9
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    • pp.1972-1978
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    • 2010
  • AAM(Active Appearance Model) is one of the most effective ways to detect deformable 2D objects and is a kind of mathematical optimization methods. The cost function is a convex function because it is a least-square function, but the search space is not convex space so it is not guaranteed that a local minimum is the optimal solution. That is, if the initial value does not depart from around the global minimum, it converges to a local minimum, so it is difficult to detect face contour correctly. In this study, an AAM-based face tracking algorithm is proposed, which is robust to various lighting conditions and backgrounds. Eye detection is performed using SIFT and Genetic algorithm, the information of eye are used for AAM's initial matching information. Through experiments, it is verified that the proposed AAM-based face tracking method is more robust with respect to pose and background of face than the conventional basic AAM-based face tracking method.

Analysis of Harmonic Mean Distance Calculation in Global Illumination Algorithms (전역 조명 알고리즘에서의 조화 평균 거리 계산의 분석)

  • Cha, Deuk-Hyun;Ihm, In-Sung
    • Journal of KIISE:Computing Practices and Letters
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    • v.16 no.2
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    • pp.186-200
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    • 2010
  • In order to render global illumination realistically, we need to accurately compute the direct and indirect illumination that represents the light information incoming through complex light paths. In this process, the indirect illumination at given point is greatly affected by surrounding geometries. Harmonic mean distance is a mathematical tool which is often used as a metric indicating the distance from a surface point to its visible objects in 3D space, and plays a key role in such advanced global illumination algorithms as irradiance/radiance caching and ambient occlusion. In this paper, we analyze the accuracy of harmonic mean distance estimated against various environments in the final gathering and photon mapping methods. Based on the experimental results, we discuss our experiences and future directions that may help develop an effective harmonic mean distance computation method in the future.

Color Image Segmentation Based on Morphological Operation and a Gaussian Mixture Model (모폴로지 연산과 가우시안 혼합 모형에 기반한 컬러 영상 분할)

  • Lee Myung-Eun;Park Soon-Young;Cho Wan-Hyun
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.43 no.3 s.309
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    • pp.84-91
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    • 2006
  • In this paper, we present a new segmentation algorithm for color images based on mathematical morphology and a Gaussian mixture model(GMM). We use the morphological operations to determine the number of components in a mixture model and to detect their modes of each mixture component. Next, we have adopted the GMM to represent the probability distribution of color feature vectors and used the deterministic annealing expectation maximization (DAEM) algorithm to estimate the parameters of the GMM that represents the multi-colored objects statistically. Finally, we segment the color image by using posterior probability of each pixel computed from the GMM. The experimental results show that the morphological operation is efficient to determine a number of components and initial modes of each component in the mixture model. And also it shows that the proposed DAEM provides a global optimal solution for the parameter estimation in the mixture model and the natural color images are segmented efficiently by using the GMM with parameters estimated by morphological operations and the DAEM algorithm.