• Journal of Power Electronics
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• v.14 no.4
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• pp.778-787
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• 2014

This study presents an input filter resonance mitigation method for an AC-DC matrix converter. This method combines the advantages of the one-cycle control strategy and the active damping technique. Unnecessary sensors are removed, and system cost is reduced by employing the grid-side input currents as feedback to damp out LC resonance. A model that includes the proposed method and the input filter is established with consideration of the delay caused by the actual controller. A zero-pole map is employed to analyze model stability and to investigate virtual resistor parameter design principles. Based on a double closed-loop control scheme, the one-cycle control strategy does not require any complex modulation index control. Thus, this strategy can be more easily implemented than traditional space vector-based methods. Experimental results demonstrate the veracity of theoretical analysis and the feasibility of the proposed approach.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.16-18
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• 2005

We show how to rapidly build a framework supporting weak code mobility by using Active XML [I]. Weak code mobility is important in mobile applications area by offering functionality at a low bandwidth cost and with little overhead imposed to the user peer architecture. Starting from already known principles involving code nobility, we give a new definition for the functionality transfer p개cess and we materialize it in a working prototype.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.2
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• pp.157-164
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• 2022

This study proposes an enhanced quadruple-Active-Bridge (QAB) converter that can solve power coupling problems. By adopting a multiple winding transformer, the equivalent circuit of a conventional QAB converter has power couplings between arbitrary output ports. This coupling is an unintended power relationship that complicates the regulation of output voltage of the multiple ports. The proposed converter can carry out power decoupling by changing the arrangement of the coupling inductor. Power transfer equations for the proposed converter and its operating principles are analyzed in detail. The power coupling caused by the transformer's leakage inductance is verified by using a proposed coupling factor that presents the relationship between inductance ratio and coupling power. In addition, the decoupling power control performance of the proposed converter is verified by simulation and a 3 kW prototype converter.

• Korean Institute of Interior Design Journal
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• v.14 no.3 s.50
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• pp.95-102
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• 2005

Guarini's architectural contribution has simply focused on the dome structure that has been known to us; however, his geometric and spatial construction has been overlooked so far Through this study, it has been demonstrated that the dome structure was simply part of geometrical forms that Guarini wanted to express ultimately and it functioned as a geometrical element such as the network combined with the entire spatial structure. The purpose of this study is to reevaluate Guarini's architectural thought by means of investigating the ultimate principles of spatial composition appeared in the late Baroque architecture through the analysis of the principles of spatial composition and organized formal Idioms by Guarini's geometrical concepts. Besides, it has been assumed that such geometrical concepts by Guarini's mathematical proportion and his reiteration and change of diagrams could be clearly distinguished from the Classical geometry in the Renaissance and Guarini. suggested a way to create a new space through more active and amusing application and transformation. In this aspect, Guarini's principles of geometric composition will be one of the role models that need to be seriously reconsidered in chaotic reality of modern architecture.

• Korean Institute of Interior Design Journal
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• v.15 no.4 s.57
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• pp.106-114
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• 2006

The purposes of natural science museums are to educate the general public on the principles and application of science, and help them understand various aspects of science technology. Data should be analyzed by considering these educational aspects of exhibition, and the methods of presenting exhibits should be decided. Accordingly, the composition of exhibition contents with various exhibition elements has an important role at natural science museums. The relation and structure of exhibition themes are significant factors in helping visitors understand the principles of science and a system of viewing circulation can be used as an important tool for understanding the flow of exhibition. In other words, at the planning stage for the composition of exhibition contents, the relation of exhibition themes as well as the circulation patterns of viewers can induce active viewing behaviors. Therefore, centering on the patterns of viewing circulation as well as on the connectivity of exhibition themes at natural science museums, the purposes of this research are: 1) to conceptualize the composition of exhibition contents; and 2) to find elements that can induce active viewing behaviors by analyzing visitors' viewing behaviors. This research was establishing an analytical indicator of contact for viewing behaviors observed from the composition of exhibition scenarios, the active viewing patterns of engagement, first contact, and repeated contact were analyzed. First, a composition pattern with a high participation rate, in contact with exhibits, was found to induce an overall-viewing circulation and have a big ring of the composition of exhibition themes. Second, by inducing a partial-viewing circulation pattern, a high rate of first contacts was observed from a ring pattern of theme connection. Even for the structure with theme connection with depth, a high frequency of contacts with various exhibits was found when exhibition themes have a ring pattern. Third, the repeated contacts were mostly found in the form of scenarios, which has a successive structure of ring and cross patterns.

• Natural Product Sciences
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• v.5 no.2
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• pp.70-74
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• 1999

In the course of a search for tumor necrosis factor $(TNF)-{\alpha}$ inhibitory compounds from medicinal plants, we identified neolignans, honokiol and magnolol, from the alcoholic extract of Magnolia offcinalis as active inhibitory principles. These compounds dose-dependently inhibited $TNF-{\alpha}$ production without displaying cytotoxicity and their inhibitory activities measured by $IC_{50}$ values were 53.7 and $61.4\;{\mu}M$, respectively.

• Journal of Elementary Mathematics Education in Korea
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• v.3 no.1
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• pp.21-39
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• 1999

In this paper, we first exam the relation between Piaget's theory of cognitive development and cognitive constructivism. With it's outcome We find three principles of constructivist teaching-learning methods for primary mathematics These are as follows 1) active learning based on self-regulatory process 2) empirical learning by self initiated activities 3) individual learning derived from present cognitive structure and fits of new experiences. Finally we introduce several examples for classroom practice applied the above principles in primary mathematics.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.115-121
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• 2001

In micro automation technology, the concurrent realization of a high resolution and a large operating rage has been achieved by a dual actuator, usually called by piggy-back system, conventionally. But, because of its manufacturing cost, the complexity of control, and the limit of overall bandwidth, the contract-free and single servo actuators have been suggested with specific applications. In this paper, we suggest a novel non-contact surface actuator suing combination of the Lorentz force and the magnetized force, and discuss the actuating principles including an analytical approach. Differently from the existing planar system, an operating range of the suggested system can be expanded by an additional attachment of active elements. Therefore, it is estimated to be suitable for the next-generation moving system.

• Natural Product Sciences
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• v.9 no.2
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• pp.105-108
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• 2003

During our research program to find DNA strand-scission agents from higher plants, the MeOH extracts of the stems of Mucuna birdwoodiana Tutcher. (Leguminosae) exhibited the most potent activity with an $IC_{50}$ value of $4.9\;{\mu}g/ml$. Thus, detailed laboratory investigation was performed, and led to the isolation of known compounds, $({\pm})$-catechin (1) and (-)-epicatechin(2) as active principles. Compounds 1 and 2 showed significant activity of DNA strand-scission with $IC_{50}$ values of 10.8 and $7.5\;{\mu}g/ml$, respectively (positive control, bleomycin: $IC_{50}\;3.3\;{\mu}g/ml$.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2033-2038
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• 2008

The CPLs(capillary pumped loops) are two phase heat transfer devices which enable active control of operating temperature of heat absorbing elements(or evaporators). Although the CPLs gain increasing interests as promising heat transfer devices for future missions such as spacecraft and commercial applications, their intrinsic complexity in operating principles makes the widespread use of these devices difficult. The key element and main cause of this complexity in operating principles is the two phase hydrodynamic accumulator or reservoir which controls the saturation state of the remaining loop and, particularly for the CPLs, it is separated from the evaporator. Thus, in this study, the operating characteristics of the CPL is investigated experimentally and theoretically. Mainly focusing on the role of reservoir the thermodynamic operating principle is examined first and the experimentally obtained steady state and transient state operating characteristics are discussed in detail.