• Geomechanics and Engineering
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• v.19 no.5
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• pp.463-472
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• 2019

The mode perturbation method (MPM) is suitable and efficient for solving the eigenvalue problem of a nonuniform soil deposit whose property varies with depth. However, results of the MPM do not always converge to the exact solution, when the variation of soil deposit property is discontinuous. This discontinuity is typical because soil is usually made up of sedimentary layers of different geologic materials. Based on the energy integral of the variational principle, a new mode perturbation method, the energy-based mode perturbation method (EMPM), is proposed to address the convergence of the perturbation solution on the natural frequencies and the corresponding mode shapes and is able to find solution whether the soil properties are continuous or not. First, the variational principle is used to transform the variable coefficient differential equation into an equivalent energy integral equation. Then, the natural mode shapes of the uniform shear beam with same height and boundary conditions are used as Ritz function. The EMPM transforms the energy integral equation into a set of nonlinear algebraic equations which significantly simplifies the eigenvalue solution of the soil layer with variable properties. Finally, the accuracy and convergence of this new method are illustrated with two case study examples. Numerical results show that the EMPM is more accurate and convergent than the MPM. As for the mode shapes of the uniform shear beam included in the EMPM, the additional 8 modes of vibration are sufficient in engineering applications.

• Journal of Ocean Engineering and Technology
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• v.10 no.3
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• pp.96-104
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• 1996

Hamilton's principle is used to derive Euler-Lagrange equations for free surface flow problems of incompressible ideal fluid. The velocity field is chosen to satisfy the continuity equation a priori. This approach results in a hierarchial set of governing equations consist of two evolution equations with respect to two canonical variables and corresponding boundary value problems. The free surface elevation and the Lagrange's multiplier are the canonical variables in Hamilton's sense. This Lagrange's multiplier is a velocity potential defined on the free surface. Energy is conserved as a consequence of the Hamiltonian structure. These equations can be applied to waves in water of finite depth including generalization of Hamilton's equations given by Miles and Salmon.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.181-188
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• 2005

In this paper, a DC smoothing filterless soft switching pulse modulated high frequency AC power conversion circuit connected to utility. frequency AC power source is proposed for consumer induction heating hot water producer, steamer and super heated steamer. The operating principle of DC link filterless utility frequency AC-high frequency AC (HF AC) power conversion circuit defined as high frequency cycloinverter is described, which can operate under a principle of ZVS/AVT and power regulation based on alternate asymmetrical PWM in synchronization with the utility frequency single phase AC positive or negative half wave voltage. The dual mode modulation control scheme based on high frequency PWM and commercial frequency AC voltage PDM for the proposed high frequency cycloinverter are discussed to enlarge its soft switching commutation operating range for wide HF AC power regulation. This high frequency cycloinverter is developed for high frequency IH Dual Packs Heater (DPH) type boiler used in consumer and industrial fluid pipeline systems. Based on the experiment and simulation results, this high frequency cycloinverter is proved to be suitable for the consumer use IH-DPH boiler and hot water producers. The cycloinverter power regulation and power conversion efficiency characteristics are evaluated and discussed.

• Korean Journal of Oriental Medicine
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• v.1 no.1
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• pp.209-244
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• 1995

The time therapy in oriental medicine is to reserch physiological activity and pathological variation with time, or time with disease. In that, this therapy is to research the development of disease, progress, diagnosis, treatment, and the meaning of preventive medicine. The theory of time therapy has been developed form heaven-human corresponding principle, and fourtimes of seasons is related with human life. After that, this theory affects in yin-yang five circle principle and organ-meridian match system. The independent development was formed later, but the origin has progressed for a logn times. in relation with time therapy, traditional acupuncture therory suggested five semen. In twenty century, the doctor rheinhold voll suggested energy exchange theory, this theory is based on time therapy, but has partial differance also too. His oppinion is this´ the energy present in the body has a circulation following the acupuncture teaching, i.e., the organs and their meridians are flooded in a certain sequence by this flowing energy. This maximum times of the organs are of physiologic and pathologic significance to man. In next time, we will discuss the indivisual theory in detail, and wil have comparison, and considering too.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.200-202
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• 2006

In this paper, a novel type of auxiliary active snubbing circuit assisted quasi-resonant soft-switching pulse width modulation inverter is proposed for consumer induction heating equipments. The operation principle of this high frequency inverter is described using switching modes and equivalent circuits. This newly developed series resonant high frequency inverter can regulate its high frequency output AC power under a principle of constant frequency active edge resonant soft-switching commutation by asymmetrical PWM control system. The high frequency power regulation and actual power conversion efficiency characteristics of consumer induction heating (IH) products using the proposed soft-switching pulse width modulation (PWM) series load resonant high frequency inverter evaluated. The practical effectiveness and operating performance of high frequency inverter are discussion on the basis of simulation and experimental results as compared with the conventional soft-switching high frequency inverter.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1511-1519
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• 2014

The objective of this paper is to propose a modelling of a small compressed air energy storage system, which drives an induction generator based on a field-oriented control (FOC) principle for a renewable power generation. The proposed system is a hybrid technology of energy storage and electrification, which is developed to use as a small scale of renewable energy power plant. The energy will be transferred from the renewable energy resource to the compressed air energy by reciprocating air compressor to be stored in a pressurized vessel. The energy storage system uses a small compressed air energy storage system, developed as a small unit and installed above ground to avoid site limitation as same as the conventional CAES does. Therefore, it is suitable to be placed at any location. The system is operated in low pressure not more than 15 bar, so, it easy to available component in country and inexpensive. The power generation uses a variable speed induction generator (IG). The relationship of pressure and air flow of the compressed air, which varies continuously during the discharge of compressed air to drive the generator, is considered as a control command. As a result, the generator generates power in wide speed range. Unlike the conventional CAES that used gas turbine, this system does not have any combustion units. Thus, the system does not burn fuel and exhaust pollution. This paper expresses the modelling, thermodynamic analysis simulation and experiment to obtain the characteristic and performance of a new concept of a small compressed air energy storage power plant, which can be helpful in system designing of renewable energy electrification. The system was tested under a range of expansion pressure ratios in order to determine its characteristics and performance. The efficiency of expansion air of 49.34% is calculated, while the efficiency of generator of 60.85% is examined. The overall efficiency of system of approximately 30% is also investigated.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.627-636
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• 1993

The so-called northern Agricultural Engineering of Farmer's courtyard Energy Ecological System is a courtyard-type energy ecological synthetic application system, that combines into one the biogas pool, pig house, toilet and plastic -membrane greenhouse in a fully-closed condition in farmer's court yard, a combination of farming with breeding industry, with bioga as the key linkage , by taking full advantage of solar energy and through bioenergy conversion technique in accordance with ecological principle.

• Structural Engineering and Mechanics
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• v.15 no.6
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• pp.669-683
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• 2003

The stochastic optimal nonlinear control of coupled adjacent building structures is studied based on the stochastic dynamical programming principle and the stochastic averaging method. The coupled structures with control devices under random seismic excitation are first condensed to form a reduced-order structural model for the control analysis. The stochastic averaging method is applied to the reduced model to yield stochastic differential equations for structural modal energies as controlled diffusion processes. Then a dynamical programming equation for the energy processes is established based on the stochastic dynamical programming principle, and solved to determine the optimal nonlinear control law. The seismic response mitigation of the coupled structures is achieved through the structural energy control and the dimension of the optimal control problem is reduced. The seismic excitation spectrum is taken into account according to the stochastic dynamical programming principle. Finally, the nonlinear controlled structural response is predicted by using the stochastic averaging method and compared with the uncontrolled structural response to evaluate the control efficacy. Numerical results are given to demonstrate the response mitigation capabilities of the proposed stochastic optimal control method for coupled adjacent building structures.

• Korean Journal of Oriental Medicine
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• v.4 no.1 s.4
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• pp.47-62
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• 1998

We explicate the forming mechanism of Sasang constitution as the principle of energy distribution which is based on the evolutionary hypothesis. The result was obtained as follows: 1. The principle of form-image (形象) in oriental medicine can be explained with the relation between structure and function that a life acquires through the adaptation and evolution. 2. The Sung-jung (性情) in Sasang constitutional medicine can be explained as the strategy for survival or the pattern of adaptation by which an individual or a species lives in this world. 3. The forming mechanism of Sasang constitutional organic phase (臟局) can be explained as the principle of energy distribution which includes three hypothesis (hypothesis of limited resources, hypothesis of preference and hypothesis of effectiveness). 4. It is postulated that the local hemodynamics is one of the most important factors that determine the difference of Sasang constitutional organic function. 5. The relation of metabolic rate, local hemodynamics and thermo-metabolism is inseparable and it is the important point of forming mechanism of Sasang constitution and the diagnosis of pulse.

• Bulletin of the Society of Naval Architects of Korea
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• v.19 no.4
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• pp.1-10
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• 1982

An experimental investigation on the energy absorption of two staged combined structures is presented, which deals with the plastic collapse test as a series of research on soft bow structure involved in a ship collision. The principle of arithmetic superposition of energy absorption is derived upon experimental analysis and based upon the characteristics of the energy absorptions of component structures. This relationship is related to the further approach toward the design of soft bow.