• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.91-103
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• 2004

A series of shaking table model tests were performed to verify the validity of similitude law, which is suggested by lai (1989) to simulate the dynamic behavior of soil-fluid-structure system for is shaking table tests. In the tests, the similitude law suggested by lai was applied to determine the length and the time scaling factors. Also, the steady state concept was used in determining the density of model backfill soil, which is a key factor in simulating the development of excess pore pressure during shaking. The similitude law was verified by checking whether three different sizes of quay walls show the identical behavior or not. The similar responses of acceleration, excess pore pressure and horizontal displacement of walls were obtained far the small and large models. However, the medium model showed larger responses than those of the small and large models because of the resonance between the frequency of input acceleration and the natural frequency of the wall system. In addition, the vertical displacement and rotational angle of the walls became larger with the increase of model size.

• Journal of Power Electronics
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• v.19 no.4
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• pp.1054-1067
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• 2019

This paper systematically investigates the influence of device parameters spread on the current distribution of paralleled silicon carbide (SiC) MOSFETs. First, a variation coefficient is introduced and used as the evaluating norm for the parameters spread. Then a sample of 30 SiC MOSFET devices from the same batch of a well-known company is selected and tested under the same conditions as those on datasheet. It is found that there is big difference among parameters spread. Furthermore, comprehensive theoretical and simulation analyses are carried out to study the sensitivity of the current imbalance to variations of the device parameters. Based on the concept of the control variable method, the influence of each device parameter on the steady-state and transient current distributions of paralleled SiC MOSFETs are verified separately by experiments. Finally, some screening suggestions of devices or chips before parallel-connection are provided in terms of different applications and different driver configurations.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.472-474
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• 1999

The design procedure originally proposed by Manabe is involved, because experiences and manual skills are necessary, especially, in the case of designing low fixed-order controllers for high-order plants, and the concept of manual skills are not clearly defined. So we propose a concept and a design procedure of Approximate Pole Placement that substitute for the manual skills. And the validity of the procedure is shown by example problems. Moreover, we also propose a procedure of adding the role of improving transient response performance to the feedforward compensator that previously has only the role of tracking in steady-state the validity of the procedure is also shown by example problems.

• Women's Health Nursing
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• v.17 no.4
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• pp.317-327
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• 2011

Purpose: This study was conducted to analyze and clarify the concept of the effective breastfeeding. Methods: This study used Walker and Avant's process of concept analysis. Results: Effective breastfeeding is how to give infant adequate milk, which fulfills needs of mother and infant, from her breast so that they can be satisfied with the process and results. It included the effective breastfeeding properties as follows: feeding behaviors (positioning, latch on, and suckling), transferring a breast milk to an infant, mother-infant interaction, and satisfying their desires (satisfaction, comfort, mother's self-confidence, infant's adequate weight gain and defecation, adequate breastfeeding interval). The antecedent of effective breastfeeding were anatomical and functional normal breast, breastfeeding knowledge and steady-state of mother, and feeding desire, rooting reflex and normal oral cavity of infant. The consequences of effective breastfeeding were exclusive breastfeeding, infant and maternal health and wellbeing, and achievement of mother and infant attachment. Conclusion: The meaning of effective breastfeeding defined in this study will contribute to develop the effectiveness breastfeeding assessment tool and the nursing intervention for ineffective breastfeeding.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.8-20
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• 2013

This paper deals with the concept design of HVDC system for controlling AC network reactive power. HVDC system can control active power and reactive power and the control concept of reactive power is similar to SVC(Static Var Compensator). Reactive power is controlled by adjusting firing angle of HVDC system under the condition that AC filters are switched. Reactive power depends on AC voltage condition, considering the steady-state and transient state to maintain the stable operation of AC network in the viewpoint of voltage stability. Therefore, in the design stage of HVDC, the reactive power required in the AC network must be considered. For the calculation of operation angle in HVDC system, the expected reactive power demand and supply status is examined at each AC system bus. The required reactive power affects the determination of the operation angle of HVDC. That is, the range of "control deadband" of operation angle should have the capability supplying the required reactive power. Finally, the reactive power control concepts is applied to 1GW BTB Pyeongtaek-Dangjin HVDC system.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1055-1059
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• 1990

This paper proposed a predictive tracking controller for the continuous-time systems by using the receding horizon concept in the optimal tracking control. This controller is the continuous-time version of the previous RHTC (Receding Horizon Tracking Control) for the discrete-time state space models. The problems in implementing the feedforward part of this controller is discussed and a approximate method of implementing this controller is presented. This approximate method utilizes the information of the command signals on the receding horizon and has simple constant feedback and feedforward gain. To perform the offset free control, the integral action is included in the continuous time RHTC. By simulation it is shown that the proposed method gives better performance than the conventional steady state tracking control.

• Journal of Wind Energy
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• v.13 no.3
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• pp.5-12
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• 2022

A methodology of wind turbine blade design has been established with PROPID code, which is an aerodynamic blade design tool developed by UIUC. PROPID code can design and analyze a wind turbine blade in a steady state flow. The methodology of wind turbine blade design includes an initial blade concept design, airfoil selection, basic design, and detailed design steps. Inverse design and performance analysis of the 2.3 MW U113 wind turbine blade was performed to verify the wind turbine blade design methodology. The differences in calculated power between PROPID code and GH Bladed code are under 1.0% in all wind conditions. Both blade shape design and performance analysis results using PROPID code are accurate. The aerodynamic characteristics of a U113 blade were investigated by computational fluid dynamics. Separation flow was captured by a Reynolds-averaged Navier-Stokes steady flow simulation using ANSYS CFX code. The numerical aerodynamic analysis methodology was verified by comparing the analysis results through CFD with BEMT-based program GH Bladed code results. Therefore, the blade design methodology will be applied to develop a super-capacity 20 MW wind turbine blade in the future.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1901-1905
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• 2004

A controller designed by CDM for a servo type system which is an augmented system constructed from a rotational inverted pendulum with an integrator added to its arm, is presented in this paper. In order to be able to apply the CDM concept, the augmented system must be linearized and converted into controllable canonical form. Then, the controller consisting of the state feedback gain matrix and an integral gain in the sense of CDM can be obtained. This shows that design procedure for the proposed controller is easy. The experimental results obtained from the rotational inverted pendulum controlled by the proposed controller show that the system response has no steady-state error, however, the oscillation amplitude of the arm angle is still significant. Therefore, in this paper, the friction compensation using Coulomb friction with stiction is also added to the controller. The oscillation amplitude of the arm angle that can be reduced remarkably is also shown in the experimental results.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.159-166
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• 2004

The capacity concept presented in the Highway Capacity Manual is for steady-state traffic flow assuming that there is no restriction in downstream flowing, which is traditionally used for planning, design, and operational analyses. In the congested traffic condition, the control objective should be to keep the congested regime from growing and to recover the normal traffic condition as soon as possible. In this control case, it is important to predict the spatial-temporal pattern of congestion evolution or dissipation and to estimate the throughput reduction according to the spatial-temporal pattern. In this context, the new concept of dynamic capacity for managing congested traffic is developed in terms of spatial-temporal evolution of downstream traffic congestion and in view of the 'input' concept assuming that flow is restricted by downstream condition rather than the 'output' concept assuming that there is no restriction in downstream flowing (e.g. the mean queue discharge flow rate). This new capacity is defined as the Maximum Sustainable Throughput that is determined based on the spatial-temporal evolution pattern of downstream congestion. And the spatial-temporal evolution pattern is estimated using the Newell's simplified q-k model.

• The Journal of Engineering Geology
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• v.13 no.2
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• pp.171-191
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• 2003

The objective of this present study is to understand long term(500 years) thermohydromechanical interaction behavior on joints adjacent to a repository cavern, when high level radioactive wastes are disposed of within discontinuous granitic rock masses, and then, to contribute this understanding to the development of a disposal concept. The model includes a saturated discontinuous granitic rock mass, PWR spent nuclear fuels in a disposal canister surrounded with compacted bentonite inside a deposition hole, and mixed bentonite backfilled in the rest of the space within a repository cavern. It is assumed that two joint sets exist within a model. Joint set 1 includes joints of $56^{\circ}$ dip angle, spaced 20m apart, and joint set 2 is in the perpendicular direction to joint set 1 and includes joints of $34^{\circ}$ dip angle, spaced 20m apart. The two dimensional distinct element code, UDEC is used for the analysis. To understand the joint behavior adjacent to the repository cavern, Barton-Bandis joint model is used. Effect of the decay heat from PWR spent fuels on the repository model has been analyzed, and a steady state flow algorithm is used for the hydraulic analysis.