• Journal of Industrial Convergence
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• v.19 no.4
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• pp.23-28
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• 2021

This paper finds the regular pattern of n = [3, ∞] for Euler square game related with n = 6(6×6=36) thirty-six officer problem that is still unsolved problem. The solution of this problem is exists for n = [3, 10] without n = 6. Also, previous researchers finds the random assigned solution for specific number using computer programming. Therefore, the solution of n = [11, ∞] Euler squares are unsolved problem because of anything but easy. This paper attempts to find generalized patterns for domains that have been extended to n = [3, ∞], while existing studies have been limited to n = [3, 10]. This paper classify the n = [3, ∞] into n = odd, 4k even, 4k+2 even of three classes. Then we find the simple regular pattern solution for n = odd and 4k even(n/2 = even). But we can't find the regular pattern for 4k+2 even(n/2 = odd).

• Journal of the KSME
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• v.52 no.12
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• pp.38-40
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• 2012

이 글에서는 지금까지 대부분 기계 제품을 만들고 발전시키는 데 사용되어 왔던 기계공학 지식이 우리 인체의 움직임을 연구하는 데 어떻게 쓰일 수 있는지 한 가지 연구 주제를 예를 들어 설명하였다. 재료역학 이론을 바탕으로 만들어진 요추 모델을 통해 외부힘과 상체의 각도에 따라 각 요추의 움직임이 어떻게 달라지는지 알아보았다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.583-587
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• 1996

형상 모델링은 CAD/CAM이나 다른 공학 응용 시스템을 구성하는 데에 있어서 중요한 기술 중에 하나이다. 그리고, 이러한 형상 모델링이 효율적으로 구현되기 위해선, 보다 효율적인 형상 모델을 구현할 수 있어야 한다.(중략)

• Journal for History of Mathematics
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• v.15 no.2
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• pp.33-48
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• 2002

In this article we study various proofs of Euler's theorem(the number of faces of any polyhedron, together with the number of vertices, is two more than the number of edges), from these proofs extract some mathematical ideas. In this paper we in detail introduce eight different proofs from various articles and textbooks.

• Journal of computational fluids engineering
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• v.19 no.2
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• pp.58-65
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• 2014

The adaptive wavelet method is studied for the enhancement of computational efficiency of three-dimensional flows. For implementation of the method for three-dimensional Euler equation, wavelet decomposition process is introduced based on the previous two-dimensional adaptive wavelet method. The order of numerical accuracy of an original solver is preserved by applying modified thresholding value. In order to assess the efficiency of the proposed algorithm, the method is applied to the computation of flow field around ONERA-M6 wing in transonic regime with 4th and 6th order interpolating polynomial respectively. Through the application, it is confirmed that the three-dimensional adaptive wavelet method can reduce the computational time while conserving the numerical accuracy of an original solver.

• Journal for History of Mathematics
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• v.17 no.3
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• pp.33-42
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• 2004

${\varrho}$ is the real constant number that appears not only in calculus but also in a real life. The concept of the number ${\varrho}$ first appeared in an appendix of Napier's work on logarithms in 1618. The early developments on the logarithm became part of an understanding of the number ${\varrho}$. In 1727, the number ${\varrho}$ was studied by Euler explicitly. It ton14 almost 100 years to understand the number ${\varrho}$ which we learn in high school nowadays. By studying the origin of the number ${\varrho}$, we can guess that many mathemetician's research in our time will have significant meaning in the future although it looks like just some calculations of cohomology or K-theory etc.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.8
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• pp.8-17
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• 2005

It is well known that preconditioning methods are efficient for convergence acceleration in the compressible low Mach number flows. In this study, the original Euler equations and three differently nondimensionalized preconditioning methods are implemented in two dimensional inviscid bump flows using the 3rd order MUSCL and DADI schemes as numerical flux discretization and time integration, respectively. The multigrid and local time stepping methods are also used to accelerate the convergence. The test case indicates that a properly modified local preconditioning technique involving concepts of a global preconditioning allows Mach number independent convergence. Besides, an asymptotic analysis for properties of preconditioning methods is added.

• Explosives and Blasting
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• v.37 no.3
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• pp.13-24
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• 2019

This paper was prepared to investigate the behavior of fragments in underwater torpedo explosion beneath a frigate or surface ship by using an explicit finite element analysis. In this study, a fluid-structure interaction (FSI) methodology, called the multi-material arbitrary Lagrangian-Eulerian (MM-ALE) approach in LS-DYNA, was employed to obtain the responses of the torpedo fragments and frigate hull to the explosion. The Euler models for the analysis were comprised of air, water, and explosive, while the Lagrange models consisted of the fragment and the hull. The focus of this modeling was to examine whether a worst-case fragment could penetrate the frigate hull located close (4.5 m) to the exploding torpedo. The simulation was performed in two separate steps. At first, with the assumption that the expanding skin of the torpedo had been torn apart by consuming 30% of the explosive energy, the initial velocity of the worst-case fragment was sought based on a well-known experimental result concerning the fragment velocity in underwater bomb explosion. Then, the terminal velocity of the worst-case fragment that is expected to occur before the fragment hit the frigate hull was sought in the second step. Under the given conditions, the possible initial velocities of the worst-case fragment were found to be very fast (400 and 1000 m/s). But, the velocity difference between the fragment and the hull was merely 4 m/s at the instant of collision. This result was likely to be due to both the tremendous drag force exerted by the water and the non-failure condition given to the frigate hull. Anyway, at least under the given conditions, it is thought that the worst-case fragment seldom penetrate the frigate hull because there is no significant velocity difference between them.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.417-420
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• 2009

본 논문에서는 유니버설 조인트의 기구학적인 해석을 위하여 원동축이 평면 내에 존재할 경우와 그렇지 않은 경우에 대하여 종동축의 속도를 관찰하였다. 평면 내의 경우는 기존 이론값과 동일하나 평면 외의 경우는 유한회전의 순서에 따라서 독립적인 결과값을 가지게 된다. 이는 오일러 각의 순서를 달리하면 표현되는 속도가 다르기 때문이며 이러한 단점을 극복하기 위하여 원동축에 4원법을 적용하였다. 수치 예제를 통하여 기존의 방법과 제시한 방법을 비교하여 제시한 방법이 일관성 있는 결과를 제공함을 확인하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.4
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• pp.456-462
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• 1986

본 논문은 Voigt형의 고체점성을 갖는 단순기지보에 외부기진력이 sin(1/2 at$^{2}$+1/3bt$^{3}$)인 꼴로 작용할 때에 축하중 및 각속도의 변화에 따른 동적 처짐 효과를 고찰하였다.