• Structural Engineering and Mechanics
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• v.54 no.5
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• pp.955-971
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• 2015

In this paper, the influence of the polled direction of piezoelectric materials on the stress distribution is studied under time-harmonic dynamical load (time-harmonic Lamb's problem). The system considered in this study consists of piezoelectric covering layer and piezoelectric half-plane, and the harmonic dynamical load acts on the free face of the covering layer. The investigations are carried out by utilizing the exact equations of motion and relations of the linear theory of electro-elasticity. The plane-strain state is considered. It is assumed that the perfect contact conditions between the covering layer and half-plane are satisfied. The boundary value problems under consideration are solved by employing Fourier exponential transformation techniques with respect to coordinates directed along the interface line. Numerical results on the influence of the polled direction of the piezoelectric materials such as PZT-5A, PZT-5H, PZT-4 and PZT-7A on the normal stresses, shear stresses and electric potential acting on the interface plane are presented and discussed. As a result of the analyses, it is established that the polled directions of the piezoelectric materials play an important role on the values of the studied stresses and electric potential.

• School Mathematics
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• v.17 no.4
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• pp.555-570
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• 2015

General and subject guideline for new curriculum are confirmed and plan to announced on September 2015. The development of instructional materials according to them will proceed. Because textbooks have the role and function to determine and control the direction and scope of teaching and learning, Textbook plays a very important role in the situation where teachers and students meet. Thus we get a significant effect depending on the structure of textbook. In this study, we analyzed differences of detail learning content according to high school textbooks focused on utilizing of definite integral. After creating the questionnaire based on it, The survey was conducted targeting for 369 high school mathematics teachers belong to 14 education offices of cities and provinces are polled out by accidental sampling method. Analyzing the results of the survey, We searched various teaching and learning method that arise due to differences of detail learning content according to high school textbooks and thereby it explored the impact on students' mathematics learning. Through this, Our intention is to offer implication about the structure of textbook detail learning contents and to derive the improvements about textbook compilation system.