• Journal of Power Electronics
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• 제16권1호
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• pp.287-296
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• 2016

Conventional maximum power point tracking (MPPT) methods are ineffective under partially shaded conditions because multiple local maximum can be exhibited on power-voltage characteristic curve. This study proposes an improved cuckoo search (ICS) MPPT method after investigating the cuckoo search (CS) algorithm applied in solving multiple MPPT. The algorithm eliminates the random step in the original CS algorithm, and the conception of low-power, high-power, normal and marked zones are introduced. The adaptive step adjustment is also realized according to the different stages of the nest position. This algorithm adopts the large step in low-power and marked zones to reduce search time, and a small step in high-power zone is used to improve search accuracy. Finally, simulation and experiment results indicate that the promoted ICS algorithm can immediately and accurately track the global maximum under partially shaded conditions, and the array output efficiency can be improved.

• Journal of Communications and Networks
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• 제18권6호
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• pp.902-912
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• 2016

Recent advances in energy harvesting (EH) technology have motivated the adoption of rechargeable mobile devices for communications. In this paper, we consider a point-to-point (P2P) wireless communication system in which an EH transmitter with a non-ideal rechargeable battery is required to send a given fixed number of bits to the receiver before they expire according to a preset delay constraint. Due to the possible energy loss in the storage process, the harvest-use-and-store (HUS) architecture is adopted. We characterize the properties of the optimal solutions, for additive white Gaussian channels (AWGNs) and then block-fading channels, that maximize the energy efficiency (i.e., battery residual) subject to a given rate requirement. Interestingly, it is shown that the optimal solution has a water-filling interpretation with double thresholds and that both thresholds are monotonic. Based on this, we investigate the optimal double-threshold based allocation policy and devise an algorithm to achieve the solution. Numerical results are provided to validate the theoretical analysis and to compare the optimal solutions with existing schemes.

• 대한한의학원전학회지
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• 제23권5호
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• pp.83-94
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• 2010

"Beijijiufa" is a book written by Wenrenqinian, 1226, Song dynasty. It provides moxibustion on acute disease. However, the book is composed with quotations by other authors such as Gehong, Zhenquan, Sunzhenren, Hwangdi Qibo and others. Sunzhenren is a dominant author out of them by quotations. 14 diseases out of 22 in acute disease, is quoted in "Qianjinfang" of Sunzhenren. I will compare texts of "Beijijiufa" with "Qianjinfang" and try to figure out differences between them just like text itself, methods of treatment, moxibution point, number of points, case of male or female and so on. As a result, comparing with "Qianjinfang", "Beijijiufa" has somehow new opinions about acute disease by moxibution in methods of treatment, moxibution point, number of points, case of male or female etc., even if it referred "Qianjinfang".

• 중국학논총
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• 제63호
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• pp.299-324
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• 2019

This essay is politico-philosophical y examining the Ho-Shang Kung's Commentary on the Lao Tzu(HSKC) and reveals that there was a concept of 'the Monistic Body' as like as G. Deleuze and P. Guattari's concept 'Body without Organs.' The main idea of the political philosophy in HSKC is mentioned as 'Governing the Body'(GB) and 'Governing the State'(GS), that means a macrobiotic hygiene and a ruling the state respectively. GB is not limited to a personal action, because HSKC is not a Yangist work. All of the prior studies have been fail to point out HSKC's true pioneer the Lu Shi Chun Qiu. But a truly dramatic turning must be belonged to Dong Zhong-shu, he was the first man that used the word Governing to the Body, it indicated a conceptional change. The Body is traditionally not a concept connected with Governing, only just the State can be. But After Dong's change, HKSC attempted again to synthesize the theories of Huang-lao school and Dong's theory about the Body and the State.

• Journal of Power Electronics
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• 제18권3호
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• pp.841-852
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• 2018

This paper presents a dual-algorithm search method (GWO-GSO) combining grey wolf optimization (GWO) and golden-section optimization (GSO) to realize maximum power point tracking (MPPT) for photovoltaic (PV) systems. First, a modified grey wolf optimization (MGWO) is activated for the global search. In conventional GWO, wolf leaders possess the same impact on decision-making. In this paper, the decision weights of wolf leaders are automatically adjusted with hunting progression, which is conducive to accelerating hunting. At the later stage, the algorithm is switched to GSO for the local search, which play a critical role in avoiding unnecessary search and reducing the tracking time. Additionally, a novel restart judgment based on the quasi-slope of the power-voltage curve is introduced to enhance the reliability of MPPT systems. Simulation and experiment results demonstrate that the proposed algorithm can track the global maximum power point (MPP) swiftly and reliably with higher accuracy under various conditions.

• Journal of Power Electronics
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• 제17권1호
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• pp.212-221
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• 2017

Permanent-Magnet Synchronous Generators (PMSGs) are used widely in Wind Power Generation Systems (WPGSs), and the Vienna rectifier was recently proposed to be used as the generator-side converter to rectify the AC output voltage in PMSG-based WPGS. Compared to conventional six-switch two-level PWM (2L-PWM) converters, the Vienna rectifier has several advantages, such as higher efficiency, improved total harmonic distortion, etc. The motivation behind this paper is to verify the performance of direct-driven PMSG wind turbine system based-Vienna rectifier by using a simulated direct-driven PMSG WPGS. In addition, for the purpose of reducing the reactive power loss of PMSGs, this paper proposes an induced voltage sensing scheme which can make the stator current maintain accurate synchronization with the induced voltage. Meanwhile, considering the Neutral-Point Voltage (NPV) variation in the DC-side of the Vienna rectifier, a NPV balancing control strategy is added to the control system. In addition, both the effectiveness of the proposed method and the performance of the direct-driven PMSG based-Vienna rectifier are verified by simulation and experimental results.

• 농촌계획
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• 제3권2호
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• pp.62-70
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• 1997

This study surveys the herb industry, which plays an important role in the economy activation of the advanced countries, and by which Choongbuk, as one of local authorities, makes the first attempt in Korea. It describes the direction of the policy and application, came to a conclusion as follows. 1. Choongbuk is arranging a Herb garden as the first step in connection with the exsiting plan, It could be highly rated because there has been no example yet in korea and therefore it could involve risks. 2. The selection of site will be decided by the Do-authorities considering traffic network and accessibility. Therefore Shi and Gun authorities could have a passive and formal attitude for this policy. 3. The size of the herb garden, by modeling Japanese and European herb garden, will be 15000 pyung(4545m), From the point of view it is a start, the herb garden has still tasks to solve, e.g. lack of experience, organizational and technological problems.

• Smart Structures and Systems
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• 제20권6호
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• pp.759-767
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• 2017

Wear and aging associated damage is a severe problem for safety and maintenance of engineering structures. To acquire structural operational state and provide warning about different types of damage, research on damage identification has gained increasing popularity in recent years. Among various damage identification methods, the Lamb wave-based methods have shown promising suitability and potential for damage identification of plate-type structures. In this paper, a comprehensive study was presented to elaborate four remarkable aspects regarding the Lamb wave-based damage identification method for plate-type structures, including wave velocity, signal denoising, image reconstruction, and sensor layout. Conclusions and path forward were summarized and classified serving as a starting point for research and application in this area.

• 한국세라믹학회지
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• 제47권1호
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• pp.39-46
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• 2010

The kinetics of cation reequilibration have been studied theoretically and experimentally in complex oxides after an external perturbation of equilibrium by temperature jumps. A general kinetic model for cation redistribution amongst non-equivalent sites in complex oxides is derived based on a local homogeneous point defect mechanism involving cation vacancies. Temperature-jump optical relaxation spectroscopy has been established to investigate cation kinetic processes in spinels and olivines. The kinetic model satisfactorily describes the experimental absorbance relaxation kinetics in cobalt containing olivines and in nickel containing spinels. It is found that the kinetics of cation redistribution in complex oxides shows a strong temperature- and composition-dependence. Activation energies for cation redistribution in Co-Mg olivines are found to range between 200 and 220 kJ/mol whereas an energy barrier of about 230 kJ/mol is observed in the case of nickel gallate spinel.

• 전기학회논문지
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• 제59권10호
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• pp.1845-1849
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• 2010

We have proposed and fabricated a Buck-Boost DC to DC Converter for Thermoelectric generator (TEG) with constant output voltage suitable for battery chargers or constant voltage supplies in the range of several watt. The experimental and simulation results have shown that the proposed method allows stable operation with maximum 86% power transfer efficiency. The proposed circuit has a merit in cost and miniaturization of a system compared to conventional MPPT algorithms, because the proposed method adopts only analog circuit without DSP or micro controller unit for calculating peak power point by iterative methods.