• Journal of Advanced Marine Engineering and Technology
• /
• v.16 no.3
• /
• pp.30-41
• /
• 1992

For the state feedback controller which measures only partial state variables, a state observer can be used to give the estimates of unmeasurable states. In this paper, the delayed state feedback method instead of the state observer for desingning a tracking controller of electro-hydraulic control system is presented. The controller design is based on augmenting the original system by one additional integral and proportional element which compensates for the effect of the integral control and on feeding back the measurable state variables and their delayed values. The performance of the proposed position control system is compared with both that of the full state feedback control system and that of the digital PID control system tuned by the Ziegler-Nichols method and by the parameter readjustment through the computer simulation. And then robustness against unmeasurable constant disturbace and parameter variations during operations is also checked.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.831-836
• /
• 2011

The study described in this paper is aimed to maintain a constant output of wind turbine system via pitch control of wind turbine using Advanced PID(APID) controller. In order to improve dynamic response characteristic in terms of pitch angle and disturbance reject, the APID controller is developed. The structure of the APID is composed with derivative P controller and new type of integral control action. This new improved integral control has concept of error window and weight function concept. The performance of the APID control technique is compared with those of conventional ones via simulation. Simulation results show that the proposed method is effective and enhanced the dynamic performance of the system.

• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.1
• /
• pp.77-82
• /
• 2010

An analytical method for robust design of the multi-loop proportional-integral (PI) controller is proposed for various types of multi-delay processes. On the basis of the direct synthesis and generalized IMC-PID approach, the analytical tuning rules of the multi-loop PI controller are firstly derived for achieving the desired closed-loop response, and the structured singular value synthesis is then utilized for the tradeoffs between the robust stability and performance by adjusting only one design parameter (i.e., the closed-loop time constant). To verify the superiority of the proposed method, the simulation studies have been conducted on a wide variety of multivariable processes. The multi-loop PI controller designed by the proposed method shows a fast, well-balanced and robust response with the minimum integral absolute error (IAE) in compared with other renowned methods.

• Nuclear Engineering and Technology
• /
• v.25 no.3
• /
• pp.457-469
• /
• 1993

JEF-1-based 50-group cross section set for fast reactor calculations was generated using NJOY system. The set was then examined by analyzing measured integral quantities such as criticality and central reaction rate ratios for 27 fast critical assemblies. The calculated results using the new set were also compared with those of ENDF/B-IV or-V-based fast set. In general, the JEF-1-based set shows an improvement in predicting measured integral quantities in comparison with the previous set. With a few exceptions, JEF-1 results are comparable to those of ENDF/B-V.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2003.05a
• /
• pp.105-108
• /
• 2003

The local motion at the top of an A-frame fixed on a research vessel for deep sea ROV floating in irregular waves is studied in the time-domain. The motion is analyzed in the time-domain using the convolution integral of the radiation forces. The memory effect functions and infinite frequency added masses are obtained from the solution of the three dimensional improved Green integral equation in the frequency domain by making use of the Fourier transformation.

• International Journal of Automotive Technology
• /
• v.8 no.6
• /
• pp.723-730
• /
• 2007

The typical design of automotive driveshafts generally utilizes Constant Velocity(CV) joints as a solution to NVH. CV joints are an integral part of vehicles and significantly affect steering, suspension, and vehicle vibration comfort levels. Thus, CV joints have been favored over universal joints due to the constant velocity torque transfer and plunging capability. Although CV joints are common in vehicle applications, current research works on modeling CV joint friction and assumes constant empirical friction coefficient values. However, such models are long known to be inaccurate, especially under dynamic conditions, which is the case for CV joints. In this paper, an instrumented advanced CV joint friction apparatus was developed to measure the internal friction behavior of CV joints using actual tripod-type joint assemblies. The setup is capable of measuring key performance of friction under different realistic operating conditions of oscillatory speeds, torque and joint installation angles. The apparatus incorporates a custom-installed triaxial force sensor inside of the joint to measure the internal CV joint forces(including friction). Using the designed test setup, the intrinsic interfacial parameters of CV joints were investigated in order to understand their contact and friction mechanisms. The results provide a better understanding of CV joint friction characteristics in developing improved automotive driveshafts.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.17 no.3
• /
• pp.166-177
• /
• 2005

This study developed the jet integral model to analyze the behavior of the wastewater discharge in the near field using the fourth order Runge-Kutta method in order to numerically solve the problems of six ordinary differential equations and six unknowns. This jet integral model used the entrainment hypothesis and the manipulation of sonle shape constant. This study also conducted the hydraulic experiments fnr single horizontal buoyant Jet using LIF through the calibration procedure. The results calculated by the previous models, CORMIX 1 and VISJET, and the proposed jet integral model were compared to the hydraulic experimental results. The centerline trajectories predicted by the proposed model were in good agreements with the experimental results in the transition region whereas the trajectories calculated by the VISJET model agreed well with the measured data in the momentum and buoyancy-dominated regions. The centerline dilution calculated by the proposed model agreed generally with the measured dilution in the intial and transition regions while the centerline dilution predicted by the CORMIX 1 was in good agreements with the experimental results in the momentum and buoyancy-dominated regions.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.11 no.3
• /
• pp.376-385
• /
• 1987

In this study, the plane stress fracture toughness and Tearing modulus are investigated for various crack ratios using the J integral. To evaluate the J integral and Tearing modulus, both experiments and estimation are used. The thickness of the low carbon steel specimens that is used in the experiments is 3mm. The type of specimen that is considered in the study is center-cracked-tension one. The measurements of crack length are performed by unloading compliance method. In the estimation of crack parameters such as the J integral and load line displacement, the Ramberg and Osgood stress strain law is assumed. Then simple formulas are given for estimating the crack parameters from contained yielding to fully plastic solutions. Obtained results are as follows; (1) When the crack ratio is in the range of 0.500 - 0.701, the plane stress fracture toughness is almost constant regardless of crack ratios. (2) The fracture toughness (J$\_$c/) and Tearing modulus (T) obtained are J$\_$c/=28.51kgf/mm, T=677.7 for base metal, J$\_$c/=31.85kgf/mm, T=742.0 for annealed metal. (3) Simpson's and McCabe's formulas which consider crack growth in estimating J integral are shown more conservative J and lower T than Rice's and Sumpter's. (4) Comparison of the prediction with the actual experimental measurements by Simpson's formula shows good agreement.

• Honam Mathematical Journal
• /
• v.23 no.1
• /
• pp.5-14
• /
• 2001

Let E be an injective module over a commutative Noetherian ring A. In this paper we will show that if I is regular ideal, then the sequence of sets $$Ass_A((I^n)^{{\star}(E)}/I^n),\;n{\in}N$$ is ultimately constant. Also we obtain some related results. (Here for an ideal J of A, $J^{{\star}(E)}$ denotes the integral closure of J relative to E.

• Journal of the Korean Mathematical Society
• /
• v.38 no.2
• /
• pp.385-408
• /
• 2001

This is an introduction to a stochastic version of E. Cartan′s symplectic mechanics. A class of time-symmetric("Bernstein") diffusion processes is used to deform stochastically the exterior derivative of the Poincare-Cartan one-form on the extended phase space. The resulting symplectic tow-form is shown to contain the (a.e.) dynamical laws of the diffusions. This can be regarded as a geometrization of Feynman′s path integral approach to quantum theory; when Planck′s constant reduce to zero, we recover Cartan′s mechanics. The underlying strategy is the one of "Euclidean Quantum Mechanics".