• 대한기계학회논문집
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• 제17권12호
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• pp.2982-2994
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• 1993

Low-velocity impact responses of composite laminates are investigated using the finite element method based on various theories. In two-dimensional nonlinear analysis, a displacement field considering higher order shear deformation and large deflection of the laminate is assumed and a finite element formulation is developed using a C$^{o}$-continuous 9-node plate element. Also, three-dimensional linear analysis based on the infinitesimal strain-displacement assumptions is performed using 8-node brick elements with incompatible modes. A modified Hertzian contact law is incorporated into the finite element program to evaluate the impact force. In the time integration, the Newmark constant acceleration algorithm is used in conjuction with successive iterations within each time step. Numerical results from static analysis as well as the impact response analysis are presented including impact force histories, deflections, strains in the laminate. Impact responses according to two typical low-velocity impact conditions are compared each other.

• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1756-1766
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• 2003

Numerical modeling is carried out to investigate forced convective heat transfer to near-critical water in developing laminar flow through a circular tube. Due to large variations of thermo-physical properties such as density, specific heat, viscosity, and thermal conductivity near thermodynamic critical point, heat transfer characteristics show quite different behavior compared with pure forced convection. With flow acceleration along the tube unusual behavior of heat transfer coefficient and friction factor occurs when the fluid enthalpy passes through pseudocritical point of pressure in the tube. There is also a transition behavior from liquid-like phase to gas-like phase in the developing region. Numerical results with constant heat flux boundary conditions are obtained for reduced pressures from 1.09 to 1.99. Graphical results for velocity, temperature, and heat transfer coefficient with Stanton number are presented and analyzed.

• 대한기계학회논문집
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• 제1권3호
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• pp.125-130
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• 1977

This is a dimensionless analysis of interior ballistics for the design of gun tube. One of the characteristics of this analysis is to ues the .ETA.$_{j}$ number which means a relative quantity of virtual work to the kimetic energy of projectile at the muzzle. In order to apply the concept of virtual work, it is assumed that the projectile is moved from the beginning to the end of bore under constant pressure of the certain travel distance of projectile. The principle of the analysis is induced from the Le Duc equation, which expresses velocity as a function of projectile travel and is based on the translation of a hyperbolic curve. From this non-dimensional analysis, the optimum design parameters of pressure in the bore, velocity and acceleration of projectile can be obtained from the table of figure without computation. This method was verified by the experimental work.k.

• 한국소음진동공학회논문집
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• 제17권4호
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• pp.350-355
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• 2007

Accelerometer mounting fixtures were prepared with the different materials(Ti and SUS). The dynamic characteristics of the mounting fixture were analyzed by finite element method(FEM), and the mode shape of each order and the displacement response for modelling the mounting fixture were analyzed by ANSYS, then resonant frequencies of the mounting fixtures with Ti and SUS were 22.700 and 23.390 kHz, respectively. The dynamic characteristics of the mounting fixture with the different positions were obtained by using laser interferometer. The response of the accelerometer was nearly a constant from 40 Hz to 500 Hz, but the change of the acceleration was increased with an increase of the frequency above 500 Hz.

• 한국항해항만학회지
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• 제28권9호
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• pp.803-808
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• 2004

In this paper, an INS compensation algorithm is proposed using the accelerometer from IMU. First, we denote the basic INS algorithm and show that how to compensate the position error when low cost IMU is used. Second, considering the ship's characteristic and ocean environments, we consider with a drift as a periodic external environment change which is affected with exact position. To develop the compensation algorithm, we use a repetitive method to reduce the external environment changes. Lastly, we verify the proposed algorithm through the experiments, where the acceleration sensor is used to acquire real data.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.69-72
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• 1996

In this paper robust tracking control scheme using the new three-segment nonlinear sliding mode technique for nonlinear rigid robotic manipulator is developed. Sliding mode consists of three segments, the promotional acceleration segment, the constant velocity segment and the deceleration segment using terminal sliding mode. Strong robustness and fast error convergence can be obtained for rigid robotic manipulators with large uncertain dynamics by using the new three-segment nonlinear sliding mode technique together with a few useful structural properties of rigid robotic manipulator. The efficiency of the proposed method for the tracking has been demonstrated by simulations for two-link robot manipulator.

• 제어로봇시스템학회논문지
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• 제6권11호
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• pp.987-994
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• 2000

A Linear Pulse Motor (LPM) is a direct drive motor that has good performance in terms of accuracy, velocity and acceleration compared to the conventional rotating system with toothed belts and ball screws. However, since an LPM needs supporting devices which maintain constant air-gap and has strong nonlinearity caused by leakage magnetic flux, friction and cogging, etc., there are many difficulties in improvement on accuracy with conventional control theory. Moreover, when designing the position controller of LPM, the modeling error and load variations has not been considered. In order to compensate these components, the neural network with conventional feedback controller is introduced. This neural network of feedback error learning type changes the current commands to improve position accuracy. As a result of experiments, we observes that more accurate position control is possible compared to conventional controller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2509-2512
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• 2005

In this paper, a position control scheme of the ink droplet is presented for the high image quality and print speed inkjet printer. The proposed scheme estimates the impact position and compensates it by control of the fire strobe time based on the dynamic equations describing the moving trajectory of the ink droplet. Compared to the conventional fire strobe control which is based on the simple synchronization the fire strobe with the position signal of the inkjet nozzle, the proposed control scheme provides more accurate impact position control during the carrier is moving with accelerated or decelerated speed as well as constant speed. The availability of printing during the acceleration and deceleration states of the carrier moving enables the print speed up and the frame size down which means the cost down.

• 대한화학회지
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• 제25권4호
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• pp.214-218
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• 1981

Solid인 Hexogen 존재하에서 hydroxyl-terminated polybutadiene과 isophorone diisocyanate의 혼성중합반응속도에 관하여 연구하였다. 중합반응속도는 Hexogen의 첨가량이 증가할 수록 빠르게 나타났지만, Hexogen의 촉매적 역할은 없었으며, 오직 entropy control에 의한 반응임을 밝혔다. 이 반응은 2차 반응속도법칙에 잘 일치하며, activation energy는 8.4 Kcal/mole로 거의 일정하다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.461-468
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• 2004

The amount of $CO_2$ and $CH_4$ that were produced during biodegradation with were measured as function of time. Also, the settlements of landfill lysimeters were measured at the same time, and the relation with LFF(landfill gas) production was investigated. The effects of leachate recycle on the acceleration of settlement were studied by comparing two lysimeters. The gas production rate constant, $^{\kappa}_{LFG}$ is obtained to predict future gas production and settlement. These will be key role factors to predict gas production patterns and residual long-term settlement.