• Journal of the Korean Society of Industry Convergence
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• v.15 no.3
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• pp.65-69
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• 2012

Since 2010, enhancement of the building energy efficiency and certification system and public office building should have been acquiring the first grade of Building Energy Efficiency. The Building Energy Efficiency Rating evaluation tool and Dynamic Analysis Energy simulation program for Building Energy Efficiency are widely used. The suitability to those programs have been discussed as a variety of programs have been used accordingly. In this study, evaluated the characteristic of Building Energy Efficiency Rating tool(ECO2) of the business building. At a result, the variables on the Weather Data, building Profile and building Load property in hourly between those Building Energy Efficiency evaluation tools have different.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.215-220
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• 2002

This paper describes a simulation model for estimation the performance of the swash plate type compressor for automotive air conditioning system. The model includes consideration of both the compression process and the dynamic behavior. Also, this study compares the results obtained from the performance simulation with experimental results. Further, the effects of the inclined angle of swash plate on the performance of swash plate type compressor are discussed.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.254-263
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• 2015

In this study, numerical simulations are carried out to investigate the dynamic SGS model effects in a Kerosene-LOx coaxial swirl injector under high pressure conditions. The turbulent model is based on large-eddy simulation (LES) with real-fluid transport and thermodynamics. To assess the effect of the dynamic subgrid-scale (SGS) model, the dynamic SGS model is compared with that of the algebraic SGS model. In a swirl injector under supercritical pressure, the characteristics of temporal pressure fluctuation and power spectral density (PSD) present comparable discrepancies dependant on the SGS models, which affect the mixing characteristics. Mixing efficiency and the probability density (PDF) function are conducted for a statistical description of the turbulent flow fields according to the SGS models. The back-scattering of turbulent kinetic energy is estimated in terms of the film thickness of the swirl injector.

• Journal of KSNVE
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• v.7 no.6
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• pp.1039-1048
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• 1997

This paper describes the effects of dual dynamic vibration absorbers attached to a primary vibration system with damping. The efficiency of dual dynamic vibration absorbers was investigated with the height of amplitude ratio at the resonance frequency ratio of the damped vibration system according to mass ratio, natural frequency ratio and damping ratio. The variation of amplitude ratio related to frequency ratio of primary vibration system is verified experimentally and theoretically according to dual dynamic vibration systems using computer program designed to find mutual relationship between two absorbers.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.2
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• pp.175-185
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• 2017

This paper presents new differential methods for computing the combined and single dynamic stability derivatives of flight vehicle. Based on rigid dynamic mesh technique, the combined dynamic stability derivative can be achieved by imposing the aircraft pitching to the same angle of attack with two different pitching angular velocities and also translating it to the same additional angle of attack with two different rates of angle of attack. As a result, the acceleration derivative is identified. Moreover, the rotating reference frame is adopted to calculate the rotary derivatives when simulating the steady pull-up with different pitching angular velocities. Two configurations, the Hyper Ballistic Shape (HBS) and Finner missile model, are considered as evaluations and results of all the cases agree well with reference or experiment data. Compared to traditional ones, the new differential methods are of high efficiency and accuracy, and potential to be extended to the simulation of combined and single stability derivatives of directional and lateral.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.4
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• pp.126-136
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• 1991

In order to reduce the possibilities of personnel injuries and damages to machines and to obtaim higher efficiency and machining accuracy in the manufacturing system, the chucking technology has recentry become important. The chucking technology of work greatly affects both the grometrical accuracy and fonctional performance of the workpiece. In this study, the dynamic gripping force of a 3-jaw power chuck is investigated on the factors of the shape of jaw and the shape of workpiece. From this investigation, the following observations are obtained. 1) The higher stiffness of workpiece is, the higher decrease of dynamic gripping force is. 2) The nearer to the root of jaw is, the higher decrease of dynamic gripping force is. 3) The centrifugal force of affectting the decrease of dynamic gripping force has to be considered in the centrifugal force of affecting jaw.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.110-122
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• 1996

The objective of this study is to understand the dynamic characterictics of OHV type valve trains and to design and optimal cam profile which will improve engine performance. A numerical model for valve train dynamics is presented, which aims at both accuracy and computational efficiency. The lumped mass model and distributed parameter model were used to describe the valve train dynamics. Nonlinear characterictics in the valve spring behavior were included in the model. Comprehensive experiments were carried out concerning the valve train dynamics, and the model was tuned based on the test results. The dynamic model was used in designing an optimal cam profile. Because the objective function has many local minima, a conventional local optimizer cannot be used to find an optimal solution. A modified adaptive random search method is successfully employed to solve the problem. Cam lobe area could be increased up to 7.3% without any penalties in kinematic and dynamic behaviors of the valve train.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.315-322
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• 2000

In this study, an algorithm analyzing dynamic mutiple-crack propagation problem by Meshfree Method is proposed. A short description of Meshfree Method especially, Element-free Galerkin (EFG) method is presented and the elastodynamic fracture theory is summarized. A numerical implementation algorithm for dynamic analysis by Meshfree Method is discussed and an algorithm for mutlple-crack dynamic propagation is also presented. A couple of numerical examples of dynamic crack propagation problem illustrate the performance of the proposed technique. The accuracy of the algorithm is studied in the first example by being compared with experimental results, and the applicability and efficiency of the developed algorithm is studied in the second example.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.1
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• pp.12-23
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• 1994

This paper proposes an optimal design software for the open-chain dynamic systems whose governing equations are expressed as differential equation. In this software, an input module and an automatic creation module of the equation of motion are developed to contrive the user's convenience. To analyze the equation of motion of the dynamic systems, variable-order and variable-stepsize Adams-Bashforth-Moulton predictor-corrector method is used to improve the efficiency. For the optimization and the design sensitivity analysis, ALM(augmented lagrange multiplier)method and adjoint variable method are adopted respectively. An output module with which the user can compare and investigate the analysis and the optimization results through tables and graphs is also provided. The developed software is applied to three typical dynamic response optimization problems, and the results compare very well with those available in the literature, demonstrating its effectiveness.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.114-121
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• 2004

Recently, the finite element absolute nodal coordinate formulation (ANCF) was developed for the large deformation analysis of flexible bodies in multi-body dynamics. This formulation is based on the finite element procedures and the general continuum mechanics theory to represent the elastic forces. In this paper, a computation method of dynamic stress in flexible multi-body dynamics using absolute nodal coordinate formulation is proposed. Numerical examples, based on an Euler-Bernoulli beam theory, are shown to verify the efficiency of the proposed method. This method can be applied for predicting the fatigue life of a mechanical system. Moreover, this study demonstrates that structural and multi-body dynamic models can be unified in one numerical system.