• 제목/요약/키워드: mathematical material

검색결과 591건 처리시간 0.028초

인체 삽입용 LC 공진형 혈압 센서 디자인 및 제작 (Design and Fabrication of Implantable LC Resonant Blood Pressure Sensor)

  • 김진태;김성일;정연호
    • 한국전기전자재료학회논문지
    • /
    • 제26권3호
    • /
    • pp.171-176
    • /
    • 2013
  • In this paper, we present a MEMS (micro-electro-mechanical system) implantable blood pressure sensor which has designed and fabricated with consideration of size, design flexibility, and wireless detection. Mechanical and electrical characterizations of the sensor were obtained by mathematical analysis and computer aided simulation. The sensor is composed of two coils and a air gap capacitor formed by separation of the coils. Therefore, the sensor produces its resonant frequency which is changed by external pressure variation. This frequency movement is detected by inductive coupling between the sensor and an external antenna coil. Theoretically analyzed resonant frequency of the sensor under 760 mmHg was calculated to 269.556 MHz. Fused silica was selected as sensor material with consideration of chemical and electrical reaction of human body to the material. $2mm{\times}5mm{\times}0.5mm$ pressure sensors fitted to radial artery were fabricated on the substrates by consecutive microfabrication processes: sputtering, etching, photolithography, direct bonding and laser welding. Resonant frequencies of the fabricated sensors were in the range of 269~284 MHz under 760 mmHg pressure.

A stochastic finite element method for dynamic analysis of bridge structures under moving loads

  • Liu, Xiang;Jiang, Lizhong;Xiang, Ping;Lai, Zhipeng;Zhang, Yuntai;Liu, Lili
    • Structural Engineering and Mechanics
    • /
    • 제82권1호
    • /
    • pp.31-40
    • /
    • 2022
  • In structural engineering, the material properties of the structures such as elastic modulus, shear modulus, density, and size may not be deterministic and may vary at different locations. The dynamic response analysis of such structures may need to consider these properties as stochastic. This paper introduces a stochastic finite element method (SFEM) approach to analyze moving loads problems. Firstly, Karhunen-Loéve expansion (KLE) is applied for expressing the stochastic field of material properties. Then the mathematical expression of the random field is substituted into the finite element model to formulate the corresponding random matrix. Finally, the statistical moment of the dynamic response is calculated by the point estimation method (PEM). The accuracy and efficiency of the dynamic response obtained from the KLE-PEM are demonstrated by the example of a moving load passing through a simply supported Euler-Bernoulli beam, in which the material properties (including elastic modulus and density) are considered as random fields. The results from the KLE-PEM are compared with those from the Monte Carlo simulation. The results demonstrate that the proposed method of KLE-PEM has high accuracy and efficiency. By using the proposed SFEM, the random vertical deflection of a high-speed railway (HSR) bridge is analyzed by considering the random fields of material properties under the moving load of a train.

화학 산업에서 수학적 최적화 기법을 적용한 사례 (Applications of Mathematical Optimization Method for Chemical Industries)

  • 김은용;허순기;이규황;이호경
    • Korean Chemical Engineering Research
    • /
    • 제58권2호
    • /
    • pp.209-223
    • /
    • 2020
  • 석유화학 제품, 컴파운드(Compound), 전지, IT 소재, 첨단소재, 제약 등 다양한 제품 군의 사업을 보유하고 있는 화학 회사에서 각 사업 부분에 있어 수요 예측, 물류, 생산, 재고, 원재료 공급의 SCM (Supply Chain Management)은 사업의 손익과 직접적으로 연결되기 때문에 그와 관련된 최적화와 시스템 역량 수준은 매우 중요하다. 본 연구는 다양한 사업 군에서 각각의 SCM이나 비효율적 영역을 개선하는 등의 역량을 고도화하기 위해 원재료를 공급하고, 제품을 생산하기 위한 공급/생산 계획 등에 있어서 수학적 최적화 방법을 적용한 사례에 관하여 다룰 것이다. 그리고 학술적인 연구에 그치는 것이 아니라 계획 수립 담당자가 실제로 자신의 일부 업무에 활용하는 것이 중요하므로 이를 위해 추가적으로 필요한 사항들을 서술하였고 각각의 적용 성과를 표현하였다. 소개가 될 사례의 첫 번째에서는 편광판 생산에 있어서 원재료 로스(Loss)를 최소화하는 것을 기반으로 하는 공급계획 최적화, 최적 손익 사업 운영계획, 편광판 연신 생산 공정의 스케줄(Schedule) 최적화를 다룰 것이다. 두 번째 사례로는 PO (Poly Olefin) 공정의 생산성 극대화를 위한 생산/포장계획 최적화에 관하여 다룰 것이고, 세 번째 사례로는 전지 생산에 있어서 전극 모델 교환을 최소화 시키는 생산계획 최적화에 대해 다룰 것이다. 네 번째로는 석유화학 특성상 선박으로 대부분의 원료 입하 및 제품 출하를 하기 때문에 한정된 부두에 여러 가지 원료 입고와 제품 출하를 위한 선박이 접안 하는 일정을 최적화 한 사례를 다룰 것이며, 마지막으로 ABS (Acrylonitrile Butadiene Styrene) 반제품 생산에 있어서 제품 Change를 최소화 하는 생산계획 최적화를 다룰 것이다.

남북한 중등학교 수학교육의 통합방안 모색 (A Comparative Study on the Secondary School Mathematics Education of South and North Korea)

  • 우정호;박문환
    • 대한수학교육학회지:수학교육학연구
    • /
    • 제12권1호
    • /
    • pp.49-70
    • /
    • 2002
  • There have recently been increasing exchanges between South and North Korea in many areas of society, involving politics, economics, culture, education. In response to these developments, research activities are more strongly demanded in each of these areas to help prepare for the final unification of the two parts of the nation. In the area of mathematics education, scholars have started to conduct comparative studies of mathematics education in South and North Korea. As a response to the growing demand of the time, in this thesis we compared the secondary mathematics education in South Korea with that in North Korea. To begin with, we examined the background of education, in North Korea, particularly predominant ideological, epistemological and teaching theoretical aspects of education in North Korea. Thereafter, we compared the mathematics curriculum of South Korea with that of North Korea. On the basis of these examinations, we compared the secondary school mathematics textbooks of South and North Korea, and we attempted to suggest a guideline for researches preparing for the unification of the mathematics curriculum of South and North Korea. As a communist society, North Korea awards the socialist ideology the supreme rank and treats all school subjects as instrumental tools that are subordinated to the dominant communist ideology. On the other hand, under the socialist ideology North Korea also emphasizes the achievement of the objective of socialist economic development by expanding the production of material wealth. As such, mathematics in North Korea is seen as a tool subject for training skilled technical hands and fostering science and technology, hence promoting the socialist material production and economic development. Hence, the mathematics education of North Korea adopts a so-called "awakening teaching method," and emphasizes the approaches that combine intuition with logical explanation using materials related with the ideology or actual life. These basic viewpoints of North Korea on mathematics education are different from those of South Korea, which emphasize the problem-solving ability and acquisition of academic mathematical knowledge, and which focus on organizing as well as discovering knowledge of learners' own accord. In comparison of the secondary school mathematics textbooks used in South and North Korea, we looked through external forms, contents, quantity of each area of school mathematics, viewpoints of teaching, and term. We have identified similarities in algebra area and differences in geometry area especially in teaching sequence and approaching method. Many differences are also found in mathematical terms. Especially, it is found that North Korea uses mathematical terms in Hangul more actively than South Korea. We examined the specific topics that are treated in both South and North Korea, "outer-center & inner-center of triangle" and "mathematical induction", and identified such differences more concretely. Through this comparison, it was found that the concrete heterogeneity in the textbooks largely derive from the differences in the basic ideological viewpoints between South and North Korea. On the basis of the above findings, we attempted to make some suggestions for the researches preparing for the unification in the area of secondary mathematics education.

  • PDF

초등학교 분수 학습에서 퀴즈네어 막대 활용에 대한 비판적 고찰 (A Critical Review on the Use of Cuisenaire Rods in Learning of Fraction)

  • 이지영
    • 한국수학교육학회지시리즈A:수학교육
    • /
    • 제56권2호
    • /
    • pp.193-212
    • /
    • 2017
  • This study focuses on cuisenaire rods that can be used when teaching fractions to elementary school students. First of all, this study critically examines the use of cuisenaire rods in learning of fraction proposed by various researches. Then, based on this review, this study explores in detail the use of cuisenaire rods in teachers' manuals developed from the revised curriculum by 2009 and in lessons related to fraction. The results of this study show that there are subtle differences in how to use cuisenaire rods in learning fractions and these subtle differences have a significant impact on students' understanding of the fractions. Therefore, the teachers should be able to accurately grasp the differences and utilize appropriate methods for teaching purpose. The followings are some of the implications for teachers or textbook developers when using cuisenaire rods in fraction learning: First, we should use cuisenaire rods in ways that can fully exploit the interpretations of the fraction as a part-whole and the fraction as a ratio. Second, we should focus on quantitative reasoning with unit to determine what each cuisenaire rod refers to. Third, it is necessary to take a more careful and sensitive approach to the use of cuisenaire rods. Teachers and textbook developers should constantly explore ways to make good use of mathematical manipulatives to help students understand conceptually in fractional learning. Furthermore, when teaching various mathematical topics using different manipulatives, I expect that there will be sufficient discussions and specific studies on how to use each of these manipulatives.

스마트러닝 수학 수업이 학업성취도, 수학적 흥미, 태도에 미치는 영향 (An Effects of Smart Learning Math Class on Academic Achievement, Mathematical Interest, and Attitude)

  • 김성태;강현민;박윤정
    • 문화기술의 융합
    • /
    • 제7권2호
    • /
    • pp.217-226
    • /
    • 2021
  • Covid -19 이후 온라인 학습에 대한 관심과 수요가 증가하면서 많은 교육기관은 더 이상 온라인 학습을 부가적인 자료로 바라보지 않고 주된 학습 수단으로 사용하게 되었다. 본 연구에서는 스마트러닝에 대한 정의를 살펴보고 실험을 통해 스마트러닝 수학 수업이 학업성취도와 수학적 흥미, 태도에 어떤 영향을 미치는지 살펴보고자 하였다. 이를 위해 집단을 구분하여 6주간 스마트러닝을 실시한 집단과 대면학습을 실시한 집단 간에 학업성취도, 수학적 흥미, 태도를 비교하였다. 그 결과, 스마트러닝을 실시한 집단이 대면학습을 실시한 집단에 비해 세 요인 모두 사전-사후 차이가 큰 것을 발견하였다. 또한 스마트러닝을 실시한 학생들은 기존의 성적 수준이 태도 변화와 학업성취도 변화 사이에 유의한 조절효과가 있었다. 구체적으로 기존의 성적이 낮은 학생들은 높은 학생에 비해 스마트러닝을 통해 태도변화 차이가 클수록 학업성취도 점수도 크게 향상하였다.

MORE ON REVERSE OF HÖLDER'S INTEGRAL INEQUALITY

  • Benaissa, Bouharket;Budak, Huseyin
    • Korean Journal of Mathematics
    • /
    • 제28권1호
    • /
    • pp.9-15
    • /
    • 2020
  • In 2012, Sulaiman [7] proved integral inequalities concerning reverse of Holder's. In this paper two results are given. First one is further improvement of the reverse Hölder inequality. We note that many existing inequalities related to the Hölder inequality can be proved via obtained this inequality in here. The second is further generalization of Sulaiman's integral inequalities concerning reverses of Holder's [7].

SENSITIVITY ANALYSIS OF A SHAPE CONTROL PROBLEM FOR THE NAVIER-STOKES EQUATIONS

  • Kim, Hongchul
    • Korean Journal of Mathematics
    • /
    • 제25권3호
    • /
    • pp.405-435
    • /
    • 2017
  • We deal with a sensitivity analysis of an optimal shape control problem for the stationary Navier-Stokes system. A two-dimensional channel flow of an incompressible, viscous fluid is examined to determine the shape of a bump on a part of the boundary that minimizes the viscous drag. By using the material derivative method and adjoint variables for a shape sensitivity analysis, we derive the shape gradient of the design functional for the model problem.

NUMERICAL SOLUTIONS FOR MODELS OF LINEAR ELASTICITY USING FIRST-ORDER SYSTEM LEAST SQUARES

  • Lee, Chang-Ock
    • Korean Journal of Mathematics
    • /
    • 제7권2호
    • /
    • pp.245-269
    • /
    • 1999
  • Multigrid method and acceleration by conjugate gradient method for first-order system least squares (FOSLS) using bilinear finite elements are developed for various boundary value problems of planar linear elasticity. They are two-stage algorithms that first solve for the displacement flux variable, then for the displacement itself. This paper focuses on solving for the displacement flux variable only. Numerical results show that the convergence is uniform even as the material becomes nearly incompressible. Computations for convergence factors and discretization errors are included. Heuristic arguments to improve the convergences are discussed as well.

  • PDF

초등학교 통계영역의 심화 교수.학습 자료에 대한 연구 : 6학년을 중심으로 (A Study on Maturity materials for Teaching and Learning of Statistics in Grade 6)

  • 박영희
    • 한국수학교육학회지시리즈C:초등수학교육
    • /
    • 제3권2호
    • /
    • pp.109-113
    • /
    • 1999
  • To improve the elementary student's ability to classify the data and obtain the information from the data through graphics, it is necessary to use the teaching and learning material which encourage the student to study with interest and is adjacent to the student's environment. In this thesis. several materials to satisfy the condition is proposed together with some remarks to direct the teaching. These materials is recommended to use for the maturity learning and teaching in grade 6.

  • PDF