• The Science & Technology
• /
• v.31 no.5 s.348
• /
• pp.25-27
• /
• 1998

근세에 들어오면서 과학은 산업. 정치의 전반적인 문제와 얽히고 그 영향으로 물리학. 수학이 발달하게 된 계기가 마련되었다. 수학연구는 16세기가 끝나면서 그 당시의 과학 ,기술적 요청에 따라 이탈리아 .독일 등 유럽에서 활발히 움직였다 17세기 '뉴턴의 만유인력의 법칙'등 5대 발견을 계기로 새로운 수학의 시대를 열었으며 18~19세기의 산업혁명과 근대 자본주의 형성 등 사회적 대변동이 근대수학의 새로운 체계를 이루는 산실이 되었다.

• The Science & Technology
• /
• v.31 no.5 s.348
• /
• pp.86-87
• /
• 1998

노벨상에 기술상이나 공학상은 아직 없다. 그러나 기술자도 노벨과학상을 수상한 예가 초창기엔 더러 있었다.1909년 무선통신발명으로 물리학상을 받은 마르코니 등 그리고 X선을 발견한 독일의 뢴트겐, 전기기사였던 퀴리부인의 사위 프레드릭퀴리 등 다수가 공과계였다 .또1차 과학혁명을 일으킨 갈릴레오나 뉴턴은 망원경을 제작하거나 발명하는 등 기술능력을 보여주었다. 우리도 과학기술 교육의 혁식으로 노벨상수상의 꿈을 이루어야 하겠다.

• Defense and Technology
• /
• no.6 s.256
• /
• pp.46-53
• /
• 2000

강직성은 우주 공간에 대해 일정한 방향을 유지하려고 하는 성질로 뉴턴의 제1법칙인 관성력을 이용한 한 형태라고 할 수 있다. 강직성은 자체 회전축의 방향을 변화시켜려는 외력에 대항하여 자이로의 지지대를 기울여도 자이로의 축을 원위치로 유지하게 하는 성질이다. 이 성질은 3개의 변수인 로터의 질량, 반경, 회전속도에 좌우된다. 강직성을 이용하여 만든 자이로를 3축 자이로 혹은 Free Mounted Gyro라 하며 3축 자이로는 항공기 계기에서 자세기준, 방향기준을 설정하는데 이용된다.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.9
• /
• pp.7-11
• /
• 2004

일상생활과 산업현장에서 측정되는 힘의 범위를 정리해 보면 Fig. 1 과 같다. 힘의 SI 단위인 1뉴턴(N : 단위 질량 1 kg에 대해 1$m/s^2$ 의 가속도를 생기게 하는 힘의 크기임 정성적으로는 사과 반쪽을 손에 들고 있을 때 느끼는 중력의 크기가 약 1 N임)을 기준으로 크게는 수십 MN($10^{6}$ N) 크기의 우주선에서 발생하는 추진력에서부터 작게는 수 PN($10^{-12}$ N) 크기의 원자들 사이의 결합력까지 그 범위가 매우 광범위하다.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2010.10a
• /
• pp.185-188
• /
• 2010

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.5
• /
• pp.375-380
• /
• 2007

The nonlinear aerodynamic analysis of wing with control surface is performed using the frequency-domain panel method. To take into consideration the nonlinear aerodynamic characteristics of wing an iterative decambering approach is introduced. The iterative decambering approach uses the known aerodynamic characteristics of airfoil to calculate the aerodynamic characteristics of wing. The multi-dimensional Newton iteration is used to account for the coupling between the different sections of wing. The present method is verified by showing that it produces results that are in good agreement with experiments. The present method will be useful for the analysis of aircraft in the conceptual design because the present method can calculate promptly the nonlinear aerodynamic characteristics of wing with a few computing resources.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.5
• /
• pp.1603-1612
• /
• 1996

The pressure loss coefficient of Newtonian and non-Newtonian fluids such as water, aqueous solutions of Carbopol-934 and Separan AP-273 and blood in the stenotic tubes are determined experimentally and numerically. The numerical analyses for flows of non-Newtonian fluids in the stenotic tubes are conducted by the finite element method. The effect of the contraction ratio and the ratio of length to diameter on the pressure drop are investigated by the experiments and numerical analysis. The pressure loss coefficients are significantly dependent upon the Reynolds number in the laminar flow regime. As Reynolds number increases, the pressure loss coefficients of both Newtonian and non-Newtonian fluids decrease in the laminar flow regime. As the ratio of length to diameter increases the maximum pressure loss coefficient increases in the laminar flow regime for both Newtonian and non-Newtonian fluids. Newtonian fuid shows the highest values of pressure loss coefficient and blood the next, followed by Carbopol solution and Separan solution in order. Experimental results are used to verify the numerical analyses for flows of Newtonian and non-Newtonian fluids. Numerical results for the maximum pressure loss coefficient in the stenotic tubes are in fairly good agreement with the experimental results. The relative differences between the numerical and experimental results of the pressure loss coefficients in the laminar flow regime range from 0.5% to 14.8%.

• Journal for History of Mathematics
• /
• v.21 no.3
• /
• pp.1-30
• /
• 2008

The success of Newton's Gravitational Theory has influenced the theory of capillarity, beginning in the early nineteenth century, by providing a major model of molecular attraction. He used the equation of the attraction of spheroids, which is expressed by second order partial differential equations, to utilize this analogy as the same kind of a particle's force, between gravitational, refractive force of light, and capillarity. The solution of the differential equation corresponds to the geometrical figure of the vessel and the contact angle which is made by the fluid. Unknown abstract functions $\varphi(f)$ represent interaction forces between molecules, giving their potential functions. By conducting several kinds of experimental conditions, it was found that the height of the ascending fluid in the tube is inversely proportional to the rayon of the tube or the distance of the plate. This model is an essential element in the theory of capillarity. Laplace has brought Newtonian mechanics to completion, which relates to the standard model of gravitational theory. Laplace-Young's equation of capillarity is applicable to minimal surfaces in mathematics, to surface tensional phenomena in physics, and to soap bubble experiments.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.6
• /
• pp.591-597
• /
• 2013

Because most existing non-Newtonian models are not suitable for application to the lattice Boltzmann method, theoretical and numerical studies in this regard remain challenging. In this study, the hydrokinetic (HK) model was modified and applied to a 3D sudden contraction-expansion channel flow, and the characteristics of the HK model flow were evaluated to generate non-trivial predictions in three-dimensional strong shear flows. The HK model is very efficient for application to the lattice Boltzmann method because it utilizes the shear rate and relaxation time. However, the simulation would be unstable in a high shear flow field because the local relaxation time sharply decreases with an increase in the shear rate in a strong shear flow field. In the HK model, it may become necessary to truncate the relaxation time and non-dimensional parameter to obtain stable numerical results.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.15 no.4
• /
• pp.675-691
• /
• 2002

The focus of this work is on the development of large-scale numerical optimization methods for optimal control of steady incompressible Navier-Stokes flows. The control is affected by the suction or injection of fluid on portions of the boundary, and the objective function of fluid on portions of the boundary, and the objective function represents the rate at which energy is dissipated in the fluid. We develop reduced Hessian sequential quadratic programming. Both quasi-Newton and Newton variants are developed and compared to the approach of eliminating the flow equations and variables, which is effectively the generalized reduced gradient method. Optimal control problems we solved for two-dimensional flow around a cylinder. The examples demonstrate at least an order-of-magnitude reduction in time taken, allowing the optimal solution of flow control problems in as little as half an hour on a desktop workstation.