• Title, Summary, Keyword: relative difference

Search Result 2,275, Processing Time 0.041 seconds

A Study on Numerical Method for Motion Analysis of Cylindrical Cam with Translate Follower (병진운동용 원통캠기구의 운동해석을 위한 수치해석법 연구)

  • 김상진;신중호;김대원;박세환
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • /
    • pp.719-722
    • /
    • 2002
  • Cylindrical cam mechanisms are used commonly in many automatic machinery. But the cylindrical cam is very difficult to design and manufacture the shape. The motion analysis of the cylindrical cam can check the accuracy between designed data and manufactured data of the cam shape and can reproduce without the cam design data. The motion analysis of the cylindrical cam consists of displacement analysis, velocity analysis and acceleration analysis. This paper performs the motion analysis of a cylindrical cam with translating follower by using a relative velocity method and a central difference method. The displacement is calculated by using the central difference method and the velocity is calculated by the relative velocity method. The relative velocity method is defined by the relative motion between follower and cam at a center of a follower roller. The central difference method is derived in the 3 dimensional space.

  • PDF

New Cyclic Relative Difference Sets Constructed from d-Homogeneous Functions with Difference-balanced Property (차균형성질을 갖는 d-동차함수로부터 생성된 새로운 순회상대차집합)

  • 김상효;노종선
    • Journal of the Korea Institute of Information Security & Cryptology
    • /
    • v.12 no.2
    • /
    • pp.11-20
    • /
    • 2002
  • In this paper, for many prime power q, it is shown that new cyclic relative difference sets with parameters (equation omitted) can be constructed by using d-homogeneous functions on $F_{q^{n}}${0} over $F_{q}$ with difference-balanced property, where $F_{q^{n} }$ is a finite field with $q^{n}$ elements. Several new cyclic relative difference sets with parameters (equation omitted) are constructed by using p-ary sequences of period $q^{n}$ -1 with ideal autocorrelation property introduced by Helleseth and Gong and d-form sequences.

A phenomenological approach to suspensions with viscoelastic matrices

  • Tanner Roger I.;Qi Fuzhong
    • Korea-Australia Rheology Journal
    • /
    • v.17 no.4
    • /
    • pp.149-156
    • /
    • 2005
  • A simple constitutive model for viscoelastic suspensions is discussed in this paper. The model can be used to predict the rheological properties (relative viscosity and all stresses) for viscoelastic suspensions in shear and elongational flow, and the constitutive equations combine a 'viscoelastic' behaviour component and a 'Newtonian' behaviour component. As expected, the model gives a prediction of positive first normal stress difference and negative second normal stress difference; the dimensionless first normal stress difference strongly depends on the shear rate and decreases with the volume fraction of solid phase, but the dimensionless second normal stress difference (in magnitude) is nearly independent of the shear rate and increases with the volume fraction. The relative viscosities and all the stresses have been tested against available experimental measurements.

Forming Simulation of Extru-Bending Process Using Multi-Billets (멀티빌렛을 사용한 압출굽힘가공의 성형 해석)

  • Park D. Y.;Jin I. T.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • /
    • pp.120-123
    • /
    • 2004
  • The bending phenomenon has been known to be occurred by the difference of velocity at the die exit. The difference of velocity at the die exit section can be obtained by the different velocity of billets inside die chamber after passing the multi-hole container. The curvature can be controlled by the two variables, the one of them is the different velocity of billets through the multi-hole container, the other is the difference of hole diameter. The bending phenomenon during extruding using four billets can be obtained by the difference of hole diameters in the multi-hole container or by the difference of relative velocity of billet inserted in the container. As results of DEFORM-3D analysis, it can be shown that bending can be obtained during extruding by the difference of relative velocity of two billets or by the difference of hole diameter, and the amount of curvature is increased by the difference of velocity and diameter. According to the shape of products, the curvature of rectangular section is bigger than the curvature of regular square section. And, it is estimated that, because the stress on the welding line is much higher than yield stress of material, the bonding of four billets can be obtained.

  • PDF

A Experimental Study on Application of KS F 2456 using Shear Wave (급속 동결 융해에 대한 콘크리트의 저항 시험방법(KS F 2456)에 전단파 적용을 위한 실험적 연구)

  • An, Ji-Hwan;Jeon, Sung-Il;Kwon, Soo-Ahn
    • International Journal of Highway Engineering
    • /
    • v.14 no.5
    • /
    • pp.57-65
    • /
    • 2012
  • PURPOSES: It is important to consider the long-term performance of concrete pavement, because concrete pavement is more exposed to the various environmental conditions than any other concrete structures. One of the several methods to evaluate the long-term performance of concrete during winter is KS F 2456. Relative dynamic modulus of elasticity shows the resistance to freezing and thawing. METHODS: To measure relative dynamic modulus of elasticity, ultra sonic is generally used. But in this study, to measure the relative dynamic modulus of elasticity, both ultra sonic and shear wave were used and then compared each other. RESULTS: The results from the measurement by ultrasonic wave and shear wave were divided into three types. Type 1 : Specimens are good and relative dynamic modulus of elasticity did not decrease until 300 cycle. Type 2 : The relative dynamic modulus of elasticity decreased from the late cycle.(about 150 cycle later) Type 3 : The relative dynamic modulus of elasticity consistently decreased from the beginning. As a result of ANOVA, there is no difference according to measuring method, in type 2 and 3. But there is a difference according to measuring method, in type 1's relative dynamic modulus of elasticity. CONCLUSIONS: It is proved that shear wave can be used to understand the damage tendency of relative freezing and thawing and to measure the relative dynamic modulus of elasticity.

Vocabulary Acquisition of Korean Learners for Academic Purposes -Focusing on the Effects of Instruction Introductory Methods of Context Inference and Activation of Background Knowledge (학문목적 한국어 학습자의 어휘 습득 연구 -문맥 추론과 배경지식 활성화를 통한 수업 도입을 중심으로-)

  • Lee, MinWoo
    • Journal of Korean language education
    • /
    • v.29 no.4
    • /
    • pp.93-112
    • /
    • 2018
  • The purpose of this study is to deal with vocabulary in KFL. As a result of this study, learners learned vocabulary on average 43 points through contextual inference and introduction of the class to activate background knowledge. In particular, the implicit method showed the highest learning rate of 52 points, and the thematic method had a 41 point-learning rate. In contrast, the semantic method was the lowest with a 25 point-learning rate. There was no significant difference in the improvement rate of upper vocabulary learners, but in the case of the lower learner, there was significant difference in the improvement rate. The difference was not significant in the post-test relative gain rate of upper learners, but there was significant in lower learners. In the delayed test relative gain rate, the difference was significant in all groups. There was correlation between vocabulary difficulty and score, but there was no correlation with the thematic method. And there was no correlation between vocabulary difficulty, improvement rate and relative gain rate in all three classes. However, content understanding, lexical grade, improvement rate, and relative gain rate showed a significant correlation.

Distributed Storage Codes with Multiple Replication Degrees Using Relative Difference Families (상대 차족을 이용한 복수 반복 차수 분산 저장 부호)

  • Park, Hosung;Kim, Cheol-Sung
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.41 no.12
    • /
    • pp.1768-1770
    • /
    • 2016
  • In this paper, we propose a construction method of fractional repetition codes, a class of distributed storage codes, using relative difference families. The proposed codes can support multiple replication degrees for data symbols. It is shown via simulation that the proposed codes store more data than the random fractional repetition codes.

ANALYSIS OF A ONE-DIMENSIONAL FIN USING THE ANALYTIC METHOD AND THE FINITE DIFFERENCE METHOD

  • Han, Young-Min;Cho, Joo-Suk;Kang, Hyung-Suk
    • Journal of the Korean Society for Industrial and Applied Mathematics
    • /
    • v.9 no.1
    • /
    • pp.91-98
    • /
    • 2005
  • The straight rectangular fin is analyzed using the one-dimensional analytic method and the finite difference method. For the finite difference method, the numbers of nodes vary from 20 to 100. The relative errors of heat loss and temperature between the analytic method and the finite difference method are represented as a function of Biot Number and dimensionless fin length. One of the results shows that the relative error between the analytic method and the finite difference method decreases as the numbers of nodes for finite difference method increase.

  • PDF

Characteristics of Relative Navigation Algorithms Using Laser Measurements and Laser-GPS Combined Measurements

  • Kang, Dae-Eun;Park, Sang-Young;Son, Jihae
    • Journal of Astronomy and Space Sciences
    • /
    • v.35 no.4
    • /
    • pp.287-293
    • /
    • 2018
  • This paper presents a satellite relative navigation strategy for formation flying, which chooses an appropriate navigation algorithm according to the operating environment. Not only global positioning system (GPS) measurements, but laser measurements can also be utilized to determine the relative positions of satellites. Laser data is used solely or together with GPS measurements. Numerical simulations were conducted to compare the relative navigation algorithm using only laser data and laser data combined with GPS data. If an accurate direction of laser pointing is estimated, the relative position of satellites can be determined using only laser measurements. If not, the combined algorithm has better performance, and is irrelevant to the precision of the relative angle data between two satellites in spherical coordinates. Within 10 km relative distance between satellites, relative navigation using double difference GPS data makes more precise relative position estimation results. If the simulation results are applied to the relative navigation strategy, the proper algorithm can be chosen, and the relative position of satellites can be estimated precisely in changing mission environments.