• Journal of Power Electronics
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• 제13권6호
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• pp.1058-1069
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• 2013

This paper proposes and designs a new output filter called an LCFL filter for application to three phase three wire shunt active power filters (SAPF). This LCFL filter is derived from a traditional LCL filter by replacing its capacitor with a C-type filter, and then constructing an L-C-type Filter-L (LCFL) topology. The LCFL filter can provide better switching ripple attenuation capability than traditional passive damped LCL filters. The LC branch series resonant frequency of the LCFL filter is set at the switching frequency, which can bypass most of the switching harmonic current generated by a SAPF converter. As a result, the power losses in the damping resistor of the LCFL filter can be reduced when compared to traditional passive damped LCL filters. The principle and parameter design of the LCFL filter are presented in this paper, as well as a comparison to traditional passive damped LCL filters. Simulation and experimental results are presented to validate the theoretical analyses and effectiveness of the LCFL filter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.296-297
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• 2005

We have investigated the quench performance of shunt reactors in the parallel connection of resistive type superconducting fault current limiter (SFCL) components based on YBCO films. To increase voltage rating, components are connected in series and to increase current level, they are connected in parallel. This method has cauesd the unbalanced quench between each components. To improve the problem, we have compared the quench properties between the current limiting components without and with shunt reactors connected in parallel. To improve the quench performance, across individual SFCL components connected the shunt reactor in parallel. The components with shunt reactors successfully produced simultaneous quench, resulting from the bypass of the fault current in the direction of the shunt reactor.

• 고전문학과교육
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• 제16호
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• pp.29-63
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• 2008

The purpose of the study is to describe the phenomena of reading classical Korean literature in middle school classrooms. This is one of a series of fundamental works to seek a desirable direction for classical Korean literature education. The results of the study are as follows. First, it was investigated which classical Korean literature middle school students read. As a result, it was found that the students read the works given mostly in their Korean language textbooks. A modern language is used for classical Korean literature in middle school textbooks. The textbooks have the largest number of tales with four pieces, followed by novels, essays, and sijos, Korean verses. Secondly, it was investigated how middle school students read classical Korean literature. It was found that they read it in class mainly through one-way lecturing by teachers. As a result of conducting a questionnaire survey of students and teachers, it was found that the lessons in classical Korean literature did not fulfill the students' expectations. Thirdly, my own real teaching cases were arranged to be presented, in connection with the matter why students should read classical Korean literature. This matter is embodied with a teacher's short verbal explanation focusing on motivation concerning the object of study.

• Journal of Power Electronics
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• 제19권6호
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• pp.1467-1476
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• 2019

Grid unbalanced faults can cause core saturation of power transformer and produce lower-order harmonics. These issues increase the electrical stress of power electronic devices and can cause a tripping of an entire HVDC system. In this paper, based on the positive-sequence and negative-sequence impedance model of a VSC-HVDC system as seen from the point of common connection (PCC), the resonance problem is analyzed and the factors determining the resonant frequency are obtained. Furthermore, to suppress over-voltage and over-current during resonance, a novel method using a virtual harmonic resistor is proposed. The virtual harmonic resistor emulates the role of a resistor connected in series with the commutating inductor without influencing the active and reactive power control. Simulation results in PSCAD/EMTDC show that the proposed control strategy can suppress resonant over-voltage and over-current. In addition, it can be seen that the proposed strategy improves the safety of the VSC-HVDC system under unbalanced faults.

• Nuclear Engineering and Technology
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• 제35권2호
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• pp.108-120
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• 2003

In assessing the long term post closure radiological safety assessment of a potential HLW repository in Korea, three categories of uncertainties exist. The first one is the scenario uncertainty where series of different natural events are translated into written statements. The second one is the modeling uncertatinty where different mathematical models are applied for an identical scenario. The last one is the data uncertainty which can be expressed in terms of probabilistic density functions. In this analysis, three different scenarios are seleceted; a small well scenario, a radiolysis scenario, and a naturally discharged scenario. The MASCOT-K and the AMBER, probabilistic safety assessment codes based on connection of sub-modules and a compartment theory respectively, are applied to assess annual individual doses for a generic biosphere. Results illustrate that for a given scenario, predictions from two different codes fairly match well each other But the discrepancies for the different scenarios are significant. However, total doses are still well below the guideline of 2 mRem/yr. Detailed analyses with model and data uncertainties are underway to further assure the safety of a Korean reference dispsoal concept.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.543-549
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• 2021

The stock market plays a crucial role in the growth of industry and trade, which eventually affects the economy. This paper studies the determinants of stock market development in Jordan using yearly time-series data (1978-2019). The autoregressive distributed lag approach is applied to examine co-integration, while the vector error correction model is employed to estimate (long-run and short-run) causal relationships. The results show that macroeconomic determinants such as gross domestic product, gross domestic savings, investment rate, credit to the private sector, broadest money supply, stock market liquidity, and inflation rate are important determinants of stock market development. These findings provide vital implications for policymakers in developed and emerging stock markets. First, economic development plays an imperative role in stock market development. Second, developing the banking sector is mandatory because it can significantly promote stock market development. Third, domestic investment is a significant determinant of stock market development, especially in emerging countries. However, it is vital to launch policies that lead to encourage investment and promote stock market development, and this could be done through (1) encouraging competition, (2) improving the institutional framework, and (3) removing trade blocks by establishing a mutual connection between foreign private investment entities and government authorities.

• 한국산업융합학회 논문집
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• 제22권2호
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• pp.219-226
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• 2019

This paper describes the development of a 500W DC/DC converter for use with a thermoelectric module(TEM). A thermoelectric device is a structure in which a P-type semiconductor and an N-type semiconductor are electrically connected in series and thermally connected in parallel. There is a feature that an electromotive force is generated by making a temperature difference between both surfaces of a thermoelectric element. This feature can be used as a renewable power source without the need for fossil energy. The proposed converter boosts the low generation voltage of the thermoelectric element to secure the voltage for the grid connection. This converter is a combination of a resonant converter for boosting and a boost-converter for output voltage control. This structure has an advantage that a voltage can be stepped up at a high efficiency and precise output voltage control is possible. We carry out simulations and experiments to verify the validity.

• 대한건축학회논문집:계획계
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• 제35권1호
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• pp.107-115
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• 2019

This research explores a historical trajectory of the Milwaukee Art Museum from its establishment to the third expansion over the last six decades. After established in 1957 by the architect, Eero Saarinen, this museum underwent three expansions led by three different architects including, David Kahler, Santiago Calatrava, and James Shields. Reasons for expanding the museum were varied. A lack of exhibition space, an absence of visual identity, and path interruption problem within urban contexts were the main factors of a series of expansion. Furthermore, this research points out that there are three issues in the process of the expansion. The first is connection issues between the downtown and the lakefront in which the museum has blocked the public flow. The second, there were controversies on the allocation of the expanded space among the main body of the decision including architects, curators, and stakeholders. The last one is relationships among architects. This is related to each architect's attitude toward the museum. Drawing on historical documents and interviews with the regional architects, I argue that the identity and values of the museum have changed over time through the expansions rather than having the invariable.

• 국제강구조저널
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• 제18권5호
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• pp.1666-1683
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• 2018

To explore seismic behavior of blind bolted concrete-filled steel tube (CFST) frames infilled with precast sandwich composite wall panels (SCWPs), a series tests of blind bolted square CFST frames with precast SCWPs under lateral low-cyclic loading were conducted. The influence of the type of wall concrete, wall-to-frame connection and steel brace setting, etc. on the hysteretic curves and failure modes of the type of composite structure was investigated. The seismic behavior of the blind bolted CFST frames with precast SCWPs was evaluated in terms of lateral load-displacement relation curves, strength and stiffness degradation, crack patterns of SCWPs, energy dissipation capacity and ductility. Then, a finite element (FE) analysis modeling using ABAQUS software was developed in considering the nonlinear material properties and complex components interaction. Comparison indicated that the FE analytical results coincided well with the test results. Both the experimental and numerical results indicated that setting the external precast SCWPs could heighten the load carrying capacities and rigidities of the blind bolted CFST frames by using reasonable connectors between frame and SCWPs. These experimental studies and FE analysis would enable improvement in the practical design of the SCWPs in fabricated CFST structure buildings.

• 한국산업정보학회논문지
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• 제14권5호
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• pp.131-137
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• 2009

제전기는 정전기를 제거하는 장치로서 평판디스플레이, 유기 EL 등의 제조 공정에서 사용하는 장치이다. 본 논문에서는 상위 컴퓨터와 다수의 제전기간에 통신이 가능하며, 각 제전기의 전원 및 제전 상태를 독립적으로 제어가 가능한 제전기용 고성능 원격 감시 장치를 개발하였다. 실험을 통하여 제어기의 핵심적인 기능인 유니트 접속, 이온발생량, 대전량, 경보상태, 그리고 제전상태가 PC와 제어기 사이에 정상적으로 송수신 되는 것을 확인하였다. 개발된 장치는 TFT-LCD, PDP, 유기 EL 등 평판제조 산업에 필요한 제전기를 고성능으로 원격 감시하는 시스템에 활용이 기대된다.