• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 G
• /
• pp.2222-2224
• /
• 1998

This paper presents a 3D feature extraction method using rough set theory. Using the stereo cameras, we obtain the raw images and then perform several processes including gradient computation and image matching process. Decision rule constructed via rough set theory determines whether a ceratin point in the image is 3D edge or not. We propose a method finding rules for 3D edge extraction using rough set.

• Computers and Concrete
• /
• 제22권2호
• /
• pp.161-166
• /
• 2018

This paper deals with the instability analysis of concrete pipes conveying viscous fluid-nanoparticle mixture. The fluid is mixed by $AL_2O_3$ nanoparticles where the effective material properties of fluid are obtained by mixture rule. The applied force by the internal fluid is calculated by Navier-Stokes equation. The structure is simulated by classical cylindrical shell theory and using energy method and Hamilton's principle, the motion equations are derived. Based on Navier method, the critical fluid velocity of the structure is calculated and the effects of different parameters such as fluid velocity, volume percent of nanoparticle in fluid and geometrical parameters of the pipe are considered. The results present that with increasing the volume percent of nanoparticle in fluid, the critical fluid velocity increase.

• Steel and Composite Structures
• /
• 제23권6호
• /
• pp.623-631
• /
• 2017

Present paper deals with the temperature-dependent buckling analysis of sandwich nanocomposite plates resting on elastic medium subjected to magnetic field. The lamina layers are reinforced with carbon nanotubes (CNTs) as uniform and functionally graded (FG). The elastic medium is considered as orthotropic Pasternak foundation with considering the effects of thermal loading on the spring and shear constants of medium. Mixture rule is utilized for obtaining the effective material properties of each layer. Adopting the Reddy shear deformation plate theory, the governing equations are derived based on energy method and Hamilton's principle. The buckling load of the structure is calculated with the Navier's method for the simply supported sandwich nanocomposite plates. Parametric study is conducted on the combined effects of the volume percent and distribution types of the CNTs, temperature change, elastic medium, magnetic field and geometrical parameters of the plates on the buckling load of the sandwich structure. The results show that FGX distribution of the CNTs leads to higher stiffness and consequently higher buckling load. In addition, considering the magnetic field increases the buckling load of the sandwich nanocomposite plate.

• Coupled systems mechanics
• /
• 제9권6호
• /
• pp.575-597
• /
• 2020

Equilibrium equations of a porous FG plate resting on Winkler-Pasternak foundations with various boundary conditions are derived using a new refined shear deformation theory. Different types of porosity distribution rate are considered. Governing equations are obtained including the plate-foundation interaction. This new model meets the nullity of the transverse shear stress at the upper and lower surfaces of the plate. The novel rule of mixture is proposed to describe and approximate material properties of the FG plates with different distribution case of porosity. The validity of this theory is studied by comparing some of the present results with other higher-order theories reported in the literature. Effects of variation of porosity distribution rate, boundary conditions, foundation parameter, power law index, plate aspect ratio, side-to-thickness ratio on the deflections and stresses are all discussed.

• 동의생리병리학회지
• /
• 제18권3호
• /
• pp.713-723
• /
• 2004

With regard of YinYang and Five Elements Theory, predominance of Yin or Yang is a key point to discuss Nourishin Ying or Reinforcing Yang. There are two major branches about studying predominance of Yin or Yang. Zhu Danxi advocated the theory that Yang was always in excess while Yin was often deficient, and thus belonged to the School for Nourishing the Yin. Zhang Jie-bin advocated that Yang is easily deficient while Yin is easily sufficient. It seems that they studied Wang Bing's 'Ministerial fire rule on all thing instead of Imperial Fire' and right Kidney Mingmen theory in Nan Jing, which are both related to the First Yang in the Book of Changes and say Mingmen fire is the host of the body. Zhu Danxi insisted that Mingmen fire was easily in excess and likely to become pathogenic fire while Water phase was easily in deficiency, so the doctors should nourish Yin and suppress Yang. Zhang Jie-bin said that Mingmen fire is vulnerable so the doctors should fortify yang and reinforce Mingmen fire. Suk Gock Master Lee thought that the Book of Changes and Nei Jing had a viewpoint of Fortify Yang as regards of some distinguished Physicians' articles about predominance of YinYang. The author's going to discribe Suk Gock's Fortify Yang Theory with viewpoints of Nei Jing and the Book of Changes.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
• /
• pp.693-697
• /
• 2005

This study was performed to develop accelerated life test method of the wind-turbine gearbox using accumulated damage theory that used to model the fatigue of parts that receive variable load. The accumulated damage theory was introduced, and the estimation of life and calculation of accelerated life test time was illustrated. As the actual application example, accelerated life test method of the gearbox was described. Life distribution of the wind-turbine gearbox was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 140,600 hours and 99% reliability for one test sample According to the accumulated damage theory, because test time can shorten in case increase test load, test time could be reduced by 1.2 years when we put the load 1.2 times of rated load than 0.93 times of rated load that is equivalent load calculated by load spectrum of the wind turbine. This time, acceleration coefficient was 21.3. This accelerated test method was used to develop accelerated test method of gear reducer, gear and bearing as well as the industrial gearbox and it is considered to be applied comprehensively to mechanical parts the fatigue of which is happened by load or pressure etc.

• 복합신소재구조학회 논문집
• /
• 제1권1호
• /
• pp.9-15
• /
• 2010

In this paper, A reinforced concrete slab bridges is analyzed by the composite laminates theory. Both the geometry and the material of the cross section of the reinforced concrete slab bridge are considered symmetrical with respect to the mid-surface so that the bending extension coupling stiffness, Bij = 0, and D16 = D26 = 0. Each longitudinal and transverse steel layer is regarded as a lamina, and material constants of each lamina is calculated by the use of rule of mixture. This slab with simple support is under uniformly distributed vertical and axial loads. In this paper, the finite difference method and specially orthotropic laminates theory are used for analysis. The result of specially orthotropic laminates theory analysis is modified to obtain the solution of the beam analysis. The result of this paper can be used for reinforced concrete slab analysis by the engineers with undergraduate study in near future.

• 연구논문집
• /
• 통권32호
• /
• pp.35-43
• /
• 2002

This study was performed to develop accelerated life test method of machanical parts using cumulative damage theory that used to model the fatigue of parts that receive variable load. The cumulative damage theory was introduced, and the estimation of life and calculation of accelerated life test time was illustrated. As the actual application example, accelerated life test method of agricultural tractor transmission was described. Life distribution of agricultural tractor transmission was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 3,000 hours and 90% reliability for one test sample. According to the cumulative damage theory, because test time can shorten in case increase test load, test time could be reduced by 482 hours when we put the load 1.1 times of rated load than 0.73 times of rated load that is equivalent load calculated by load spectrum of the agricultural tractor. This time, acceleration coefficient was 11.7. This accelerated test method was used to develop accelerated test method of gear reducer, hydraulic hose and bearing as well as agricultural tractor transmission and it is considered to be applied comprehensively to machanical parts the fatigue of which is happened by load or pressure etc.

• Steel and Composite Structures
• /
• 제30권6호
• /
• pp.603-615
• /
• 2019

In the present work, free vibration of beams made of imperfect functionally graded materials (FGMs) including porosities is investigated. Because of faults during process of manufacture, micro voids or porosities may arise in the FGMs, and this situation causes imperfection in the structure. Therefore, material properties of the beams are assumed to vary continuously through the thickness direction according to the volume fraction of constituents described with the modified rule of mixture including porosity volume fraction which covers two types of porosity distribution over the cross section, i.e., even and uneven distributions. The governing equations of power law FGM (P-FGM) and sigmoid law FGM (S-FGM) beams are derived within the frame works of classical beam theory (CBT) and first order shear deformation beam theory (FSDBT). The resulting equations are solved using separation of variables technique and assuming FG beams are simply supported at both ends. To validate the results numerous comparisons are carried out with available results of open literature. The effects of types of volume fraction function, beam theory and porosity volume fraction, as well as the variations of volume fraction index, span to depth ratio and porosity volume fraction, on the first three non-dimensional frequencies are examined in detail.

• Structural Engineering and Mechanics
• /
• 제66권5호
• /
• pp.583-594
• /
• 2018

A theoretical formulation based on the linearized potential theory, the Descartes' rule and the extremum optimization method is presented to calculate the critical distance of lifting points of the fully balanced hoist vertical ship lift, and to study pitching stability of the ship lift. The overturning torque of the ship chamber is proposed based on the Housner theory. A seven-free-degree dynamic model of the ship lift based on the Lagrange equation of the second kind is then established, including the ship chamber, the wire rope, the gravity counterweights and the liquid in the ship chamber. Subsequently, an eigenvalue equation is obtained with the coefficient matrix of the dynamic equations, and a key coefficient is analyzed by innovative use of the minimum optimization method for a stability criterion. Also, an extensive influence of the structural parameters contains the gravity counterweight wire rope stiffness, synchronous shaft stiffness, lifting height and hoists radius on the critical distance of lifting points is numerically analyzed. With the Runge-Kutta method, the four primary dynamical responses of the ship lift are investigated to demonstrate the accuracy/reliability of the result from the theoretical formulation. It is revealed that the critical distance of lifting points decreases with increasing the synchronous shaft stiffness, while increases with rising the other three structural parameters. Moreover, the theoretical formulation is more applicable than the previous criterions to design the layout of the fully balanced hoist vertical ship lift for the ensuring of the stability.