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任賢準,金雄起 弘益大學校 科學技術硏究所 1998 科學技術硏究論文集 Vol.9 No.1
The frequency-domain characteristics of elastic waves scattered from a cylindrical elastic scatterer have been studied. Both in the forward and backward and backward directions, the scattered elastic waves have shown fluctuating behavior in the frequency domain. In order to explain this behavior and to study the possibility of characterizing the scatterer from its resonance signal, it has been attempted to apply the concept of the acoustic resonant scattering theory to the elastic-elastic scattering problem. Yet, it has been found that the dominant physical phenomena of elastic-elastic scattering is quite different from that of the elastic-fluid scattering phenomena. Therefore, this approach can not be applied to the present problem at this stage of the development of the resonant scattering theory. The result of this study can be utilized as a good foundation for elastic wave scattering from elastic inclusions of similar geometrical shape.
任賢準,白은솔 弘益大學校 科學技術硏究所 2002 科學技術硏究論文集 Vol.13 No.-
As an attempt to further improve the reliability and effectiveness of ultrasonic testing (UT), a two-dimensional numerical simulator of UT is desired. Such a simulator may be established by combining the previous mass-spring lattice model (MSLM) that consists of mass-points and springs and transducer models. Models of transmitting and receiving piezoelectric transducers are introduced in this paper with some numerical results. Using the models, various problems having typical UT setups are addressed, and the computed results are discussed. The numerical results appear to be physically reasonable though they should be validated through future works.
Simulation of Ultrasonic Waves in Austenitic Welds using the Mass-Spring Lattice Model
Baek, Eunsol,Yim, Hyunjune 홍익대학교 과학기술연구소 2006 Hongik Journal of Science and Technology Vol.10 No.-
Feasibility is studied for an application of the mass-spring lattice model (MSLM), a numerical model previously developed for unidirectional composites, to the numerical simulation of ultrasonic inspection of austenitic welds modeled as transversely isotropic. Fundamental wave processes, such as propagation, reflection, refraction, and diffraction of ultrasonic waves in such an inspection are simulated using the MSLM. All numerical results show excellent agreement with the analytical results. In conclusion, a great potential of the MSLM in numerically simulating ultrasonic inspections of austenitic welds has been manifested in this work, though significant further efforts will be required to develop a model with field practicality.
고체내 탄성파 전파의 수치해석을 위한 질량스프링 모델 개발
孫榮薰,任賢準 弘益大學校 科學技術硏究所 1999 科學技術硏究論文集 Vol.10 No.1
A mass-spring lattice model is used to develop a numerical analysis which can simulate the phenomena of elastic wave propagation and scattering effectively. In order to confirm the reliability of their numerical results, the consistency, convergence, stability and accuracy of the algorithms are studied using the Taylor series expansion and the von Neumann analysis. As a result, the optimum size of time step is found for a given mesh size, such that more accurate numerical solution can be obtained in high frequency regime, along with significant saving of computation time. Numerical results have been obtained for fundamental problems in ultrasonic testing such as plane waves incident on cracks. All numerical results have shown excellent agreements with analytical results, and the reflected, diffracted, head, and Rayleigh waves have been observed. An improved mass-spring lattice model is shown to produce more accurate results for surface wave propagation than the previous models.
Interdisciplinary and International Collaborative Education for Product Design
Haeseong Jee,Hyunjune Yim,Byongjoo Kim,Alexander Brezing,Manuel Lower (사)한국CDE학회 2010 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8
The delineated approach provides an educational concept for Collaborative Product Development. It aims at teaching and training skills to accomplish collaborative product development projects as the head of the team as well as a team member. Attention is especially paid to heterogeneous teams of different skills, knowledge, specialization, ambition, location as well as cultural background. As Collaborative Engineering aggravates the definition of structures the proposed approach ceases from the common focus on curriculum-driven education. Instead, the approach incorporates principles of active learning, an approach developed in the early 90s, for exercises. Whilst base knowledge is imparted by means of conventional frontal instruction lectures, the according skills are trained in line with exercises lessons encouraging active participation. A novel exercise concept has been developed to cope with the challenges raised by Collaborative Engineering. This concept stipulates a realistic simulation of a collaborative product development environment. For that purpose, cooperation among the Institute for Engineering Design, RWTH Aachen University, Germany and the Mechanical & System Design Engineering (MSDE) Department as well as the Industrial Design Department, both of Hongik University, Korea has been established. Students from the three departments participate in cooperating project teams to develop a certain product. During the project, the lecturers just assist as consultants, acting if explicitly asked for help by the students. It is intended to let critical situations emerge as under realistic conditions, so the students learn by first hand when and how certain techniques can be applied.