• Journal of Acupuncture Research
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• v.35 no.4
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• pp.176-181
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• 2018

Background: Low electrical impedance at acupoints is a familiar concept, and it has also been found that this increases with poor organ function. Kovich hypothesizes that organ states are communicated to their related acupoints in real time, and this experiment set out to test this. Methods: The electrical impedance at 4 digestion-related acupuncture points (acupoints) was recorded over a 14-hour period and a food diary was recorded. The readings were taken in 23 sessions, between which the participant continued his usual daily routine. Results: The impedance at all the monitored acupoints varied considerably throughout the day, and the peaks were aligned with periods of high stomach activity. Conclusion: Variations in stomach function produced corresponding variations in the impedance at key stomach-related acupoints. However, the experiment was limited in that samples were only taken at around 30-minute intervals, and further investigations are needed to explore this phenomenon in more detail.

• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.722-727
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• 1995

The electrochemical impedance spectra of polyaniline film prepared by cyclic voltammetry have been investigated in 0.1 M aqueous sulfuric acid solution. Charge transfer resistances were rather low at the oxidized states in agreement with the conductive behavior reported at these potentials. The corresponding exchange current densities were very high. Large values of capacitance associated with the polymer have been found which vary as a function of the electrode potentials. An equivalent electrical circuit has been deduced from the impedance data. It was therefore possible to obtain the parameters of the ionic mass transport within the film.

• Structural Engineering and Mechanics
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• v.6 no.2
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• pp.173-183
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• 1998

In the shape design of flexible structures, it is useful to predict the initial shape from the desirable large deformed shapes under some loading conditions. In this paper, we present a numerical procedure of an initial shape determination problem for hyperelastic materials which enables us to calculate an initial shape corresponding to the prescribed deformed shape and boundary condition. The present procedure is based on an Arbitrary Lagrangian-Eulerian (ALE) finite element method for hyperelasticity, in which arbitrary change of shapes in both the initial and deformed states can be treated by considering the variation of geometric mappings in the equilibrium equation. Then the determination problem of the initial shape can be formulated as a nonlinear problem to solve the unknown initial shape for the specified deformed shape that satisfies the equilibrium equation. The present approach can be implemented easily to the finite element method by employing the isoparametric hypothesis. Some basic numerical results are also given to characterize the present procedure.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.73-78
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• 2015

According to the characteristic of carrier-based aircraft, the method of solving safe set during arresting landing is discussed in this paper based on optimal control and invariant set theory. The safe sets of carrier aircraft are evaluated in different states on the characteristic of longitudinal augmented system by using the level set method. Then, the influence on the boundary of safe set under various factors is analyzed. At last, the maneuverability envelope protection is established based on the corresponding theory, and the validity of the system is verified through simulation. The results demonstrate preliminarily that: compared with mass and thrust, the elevator is the greatest influence factor for the boundary of safe set; the dynamic trajectory of carrier-based aircraft can be located at the interior of safe set effectively with the maneuverability envelope protection.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.336-341
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• 2013

Power converter plays a very important role in switched reluctance motor (SRM) systems, and it is also the easiest one to experience failures. Power converter faults will cause the motor to run in non equilibrium states, and a long time fault operation will lead to motor and other modules damaged, and make the system completely lose working stability. This paper uses an asymmetric bridge converter as the research object with three-phase SRM, employs the wavelet packet decomposition for the phase currents. It analyzes and studies the short circuit fault condition of IGBT, uses an energy discrete degree of the wavelet packet nodes as the fault characteristic, and conducts the corresponding experimental and simulation analysis to verify the effectiveness and practicality of the proposed method.

• Proceedings of the Korean Magnestics Society Conference
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• 2011.12a
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• pp.97-97
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• 2011

The analogy between spin configurations in spin ice materials like $Ho_2Ti_2O_7$ and proton configurations in water ice, $H_2O$, has been appreciated for many years (see Bramwell and Gingras, Science, 294, 1495, 2001). However it is only in the last few years that this equivalence has been extended into the realm of electrodynamics. In this talk I shall describe our recent experimental work that identifies magnetic charges ("monopoles"), transient magnetic currents ("magnetricity") and the universal properties expected of an ideal magnetic Coulomb gas (magnetic electrolyte - "magnetolyte"). These universal properties include the Onsager-Wien effect, "corresponding states" behaviour, Debye-Huckel screening and Bjerrum pairing. I will describe experimental results for both traditional spin ice materials ($Ho_2Ti_2O_7$, $Dy_2Ti_2O_7$) and a recently discovered system ($Dy_2Ge_2O_7$).

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.29-42
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• 2017

The purpose of the present study is the presentation of the appropriate element and shape function in the solution of the neutron diffusion equation in two-dimensional (2D) geometries. To this end, the multigroup neutron diffusion equation is solved using the Galerkin finite element method in both rectangular and hexagonal reactor cores. The spatial discretization of the equation is performed using unstructured triangular and quadrilateral finite elements. Calculations are performed using both linear and quadratic approximations of shape function in the Galerkin finite element method, based on which results are compared. Using the power iteration method, the neutron flux distributions with the corresponding eigenvalue are obtained. The results are then validated against the valid results for IAEA-2D and BIBLIS-2D benchmark problems. To investigate the dependency of the results to the type and number of the elements, and shape function order, a sensitivity analysis of the calculations to the mentioned parameters is performed. It is shown that the triangular elements and second order of the shape function in each element give the best results in comparison to the other states.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.3
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• pp.145-153
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• 2004

A nonlinear adaptive speed observer is designed for the sensorless control of induction motors. In order to design the speed observer, the measurements of the stator currents and the estimates of the rotor fluxes are used. The sliding mode cascade observer is designed to estimate the time derivatives of the stator currents. The open-loop observer is designed to estimate the rotor fluxes and its time derivatives using the stator current derivatives. The adaptive observer is also designed to estimate the rotor resistance. Sequentially, the rotor speed is calculated using these estimated values. It is shown that the estimation errors of the corresponding states and the parameters converge to the specified residual set. It is also shown that the speed controller using these estimates is performed well. The simulation examples are represented to investigate the validity of the proposed observers for the sensorless control of induction motors.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2057-2059
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• 2001

A nonlinear adaptive speed controller is designed for induction motors. Only the measurement of the stator current is used to design the controller and the observers. The sliding mode cascade observer is introduced to estimate the stator current and its time derivatives. The open-loop observer are designed to estimate the rotor flux and its time derivatives. The adaptive observer is also designed to estimate the rotor resistance. Sequentially, the rotor speed can be calculated using these estimated values. It is shown that the estimation errors of the corresponding states and the parameter converge to the specified residual set. It is also shown that the speed controller using these estimates is performed well. The experimental results are represented to investigate the validity of the proposed observer and controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.406-410
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• 2005

The wind turbine, Europe and the United States are different with the standards process each other when the manufacturing company which in order to demand the standards process to a construction in the multi country with interested parties of the corresponding nation to, always the re-agreement is difficult. Korean wind turbine also detail there is not a standard, when it produces and establishes of wind turbine, the problem point occurs. It is like that investigation of international standards system it leads and when it prepares the Acoustic noise measurement of the Wind Turbine Systems of Korea, it prepares the base for industrial development wind turbine of Korea.