• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.1091-1096
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• 1989

All mechanical systems have saturation nonlinearity in actuators or in final control elements. When controllers have integral action, reset windup can cause instability as well as make the system performance unsatisfactory. In this study, an intelligent limiter which needs no tuning of parameters is tested with the PDF controller used for control of a second order plant. This paper presents analysis of the stability of the system using the describing function method and the Nyquist stability theorem. The improvement of the system performance by the limiter is illustrated by computer simulations.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.281-282
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• 2003

Numerical investigations are carried out to study the mass flux and temperature distribution in a calandria using a 3-D RANS code. The computations made for simulations of flow and convective heat transfer with near-to working conditions. The work provides an estimate of the safe working limits of the heat dissipation by virtue of prediction of the 'hot spots' in the calandria. The work assumes significance for preliminary designs of the reactors and for detailed critical parametric analysis that would be otherwise more expensive.

• The Journal of the Acoustical Society of Korea
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• 제16권3E호
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• pp.62-68
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• 1997

In this paper, a modified adaptive sign (MAS) algorithm based on a mixed norm error criterion is proposed. The mixed norm error criterion of be minimized is constructed as a combined convex function of the mean-absolute error and the mean-absolute error to the third power. A convergence analysis of the MAS algorithm is also presented. Under a set of mild assumptions, a set of nonlinear evolution equations that characterizes the statistical mean and mean-squared behavior of the algorithm is derived. Computed simulations are carried out to verify the validity of our derivations.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.223-228
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• 2001

In this paper, crashworthiness of the KHST carbodies is evaluated by numerical simulation under the SNCF accident scenario (collision against a movable rigid mass of 15 ton at 110 kph) and the scenario of train-to-train collision at 30 kph. The numerical results of the several simulations, such as the accident collided against a deformable dump truck of 15 tons at 110 kph, the driver's dummy analysis using the integrated analysis method, and the accident of train-to-train collision for the first three units at 30 kph, show good performances in the viewpoint of energy absorption and survival space.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.459-462
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• 1997

This paper presents a optimal PWM patterns, applied to voltage source inverter fed traction motor drives. To derive a PWM patterns of low harmonic characteristic, the analysis and simulations of several PWM techniques are carried out. The acquired PWM patterns can reduce the harmonics and switch the GTOs with low frequency.

• 한국공작기계학회논문집
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• 제11권3호
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• pp.72-79
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• 2002

Though the laser cutting process is increasingly used in industry, a process automation and systematic database is still yet to be developed. In this study, as the fundamental step toward the construction of a reliable process expert system, a laser cutting quality monitoring/analysis system is developed based on simulations and experimental results. The relations between laser process parameters and laser cutting surface quality parameters such as kerf geometry, striation, surface roughness and dross formation are characterized and analyzed. A graphical user interface is used to visualize the results.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.105-106
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• 2012

This study is numerical analysis about optimal conditions of GDICI (gasoline direct injection compression ignition) engine operation using intake preheating. Numerical modeling was performed by using the KIVA-3V Release2 code integrated Chemkin chemistry solver II. For validation of numerical model, experiments were performed on a single-cylinder engine. Throughout the numerical simulations under variable conditions, the ranges of optimal conditions were found.

• 한국전자파학회논문지
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• 제10권6호
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• pp.935-950
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• 1999

A multiresolution time-domain analysis scheme is derived for the analysis of microwave structures by using Haar wavelets to discretize the Maxwell's curl equation. This technique requires less computational effort than the conventional FDTD method because larger space grid can be used in the simulations. To validate this scheme, several 2-D·3-D microwave structures are simulated and the results are compared with those of the conventional FDTD scheme.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1121-1123
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• 1997

The control strategy for damping analysis of STATCON is derived based on an energy function of the power system equation. The center-of-angle(COA) coordinated system by a simple equivalent physical system is used and the control law for this system is induced for FACTS devices as TCSC and STATCON. Damping results from the transient performance simulations carried out on the model system.

• 한국분말재료학회지
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• 제5권1호
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• pp.57-63
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• 1998

The densification behaviors of rapidly solidified Al-Si alloys under high temperature processing were investigated. In general, it was difficult to establish optimum process variables for forging condition through experimentation, because this was costly and time consuming. In this paper, to overcome these problems, we compared the experimental result to the finite element analysis for forging processes of rapidly solidified Al-Si alloys. The results of these simulations helped understand the distribution of relative density during various forging processes. This information is expected to assist in improving rapidly solidified Al-Si alloys forging operations.