• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.1
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• pp.44-51
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• 2003

The module UPS can flexibly implement expansion of power system capacities. Further-more, it can be used to build up the parallel redundant system to improve the reliability of power system operation. To realize the module UPS, load sharing without interconnection among parallel connecting modules as well as a small scale and lightweight topology is necessary. In this paper, the three-arm converter/inverter is compared with the general full-bridge and half-bridge topology from a practical point of view and chosen as the module UPS topology. The switching control approaches based on a pulse width modulation of the converter and inverter of the system are presented independently. The frequency and voltage droop method is applied to parallel operation control to achieve load sharing. Two prototype 3㎸A modules are designed and implemented to confirm the effectiveness of the pro-posed approaches. Experimental results show that the three-arm UPS system has a high power factor, a low distortion of output voltage and input current, and good load sharing characteristics.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2522-2525
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• 1999

Buck converter is considered to be one of the most widely used DC-DC converters due to its simple structure and high reliable performance. However, when it be combined with thin-film inductor, its own low inductance requires higher switching frequency in order to maintain optimum output ripple voltage and thus gives rise to extra switching losses. In view to overcoming such a technical in-convenience, soft switching fashion is suggested such as zero-voltage-switching of which an well known example is a Zero-Voltage-Switching clamp voltage(ZVS-CV) converter for which low inductance is imperatively required for ZVS operation. In order to support our suggestion, a 1W of ZVS-CV buck converter( Vo=3.3V, Iomax=0.3A, fs= 1.2MHz) is built by use of thin-film inductor, and then tested for comparing the measured efficiency between ours and conventional one. As the our results. the efficiency is improved about 2% at full load by the application of our concept.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.11-12
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• 2010

PSC girder with holed web have several benefits. Most of all placing tendon anchorage in the holes can make prestressing forces be loaded stepwise. In addition it can reduce the self-weight of the beams and increase the span length of beams. And holed web might minimize the interference of view. In this study, a 50-meter long full scale multilevel post-tensioned PSC girder was fabricated and modal test was carried out. In order to obtain precise frequency response, vibration exciter was placed at the middle of the girder and excited with several frequencies. Natural frequency and damping ratio were evaluated from FFT and PSD using the obtained frequency response and compared with numerical analysis result.

• Journal of the Speleological Society of Korea
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• no.66
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• pp.95-109
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• 2005

About 30 limestone caves have already been developed at the basin of the River Dong. baekyong Cave, Hwaam Cave, and Jeolgol Cave are of great worth, not noly as a matter of study, but as a matter of the tourist resources they develop. Among them Baekyong Cave is the best. I'm going to give a full detailed account of cave deposits and cave phenomena focused on its view to preserve the looks of Baekyong Cave by analyzing the speleothem of Baekyong Cave and cave system scientifically and systematizing them. Baekyong Cave, Natural Monument Ho. 260, is on the verge of being submerged. Peculiar things in Baekyong Cave are 1) pseudo stalgmite 2) anthodites 3) erratic stalagmites 4) cave shield 5) lost river 6) cave flint 7) pit fall but I have also mentioned general and related matters.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.242-259
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• 2015

Three-dimensional video coding is one of the main challenges restricting the widespread applications of 3D video and free viewpoint video. In this paper, a novel fractal coding algorithm with motion-vector-field-based motion estimation for depth map sequence is proposed. We firstly add pre-search restriction to rule the improper domain blocks out of the matching search process so that the number of blocks involved in the search process can be restricted to a smaller size. Some improvements for motion estimation including initial search point prediction, threshold transition condition and early termination condition are made based on the feature of fractal coding. The motion-vector-field-based adaptive hexagon search algorithm on the basis of center-biased distribution characteristics of depth motion vector is proposed to accelerate the search. Experimental results show that the proposed algorithm can reach optimum levels of quality and save the coding time. The PSNR of synthesized view is increased by 0.56 dB with 36.97% bit rate decrease on average compared with H.264 Full Search. And the depth encoding time is saved by up to 66.47%. Moreover, the proposed fractal depth map sequence codec outperforms the recent alternative codecs by improving the H.264/AVC, especially in much bitrate saving and encoding time reduction.

• Journal of Arbitration Studies
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• v.8 no.1
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• pp.269-291
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• 1998

Change of circumstances subsequent to formation of international business contract raises two issues on both parties' obligation to perform business transaction concerned. One is impossibility of performance due to events beyond control of parties and the other is adaption of contract. In Anglo-American Law such an impossibility of performance is provided by the doctrine of Frustration and the doctrine of Practicability(UCC 2-615). In practice a "force majeure" clause should be included in contract defining the parties' mutual rights and duties if certain events beyond their control occur to safeguard themselves against possible impossibility. On the other hand the tendency of international trade is that alongside sales contracts, there are contract for supplies, for furnishing raw materials, for building industrial complexes, and transferring technology. One characteristic of these agreements is their duration. For in order to carry out these agreements, it is necessary to complete a series of closely interrelated operations which, in the normal course of events, take place over a number of years. It is often difficult for the parties, when finalizing their contract, to have a full grasp of all of the factors governing their relations. With a view to resolving difficulties such as compromise the continuous performance of a contract, parties may insert a regulatory clause in their contract providing for intervention by a third person after stating in specific and detailed fashion the circumstances in which their contract may be adapted.

• Wind and Structures
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• v.24 no.1
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• pp.59-78
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• 2017

Non-stationarity and non-Gaussian property are two of the most important characteristics of wind. These two features are studied in this study based on wind speed records measured at different heights from a 325 m high meteorological tower during the synoptic wind storms. By using the time-frequency analysis tools, it is found that after removing the low frequency trend of the longitudinal wind, the retained fluctuating wind speeds remain to be asymmetrically non-Gaussian distributed. Results show that such non-Gaussianity is due to the weak-stationarity of the detrended fluctuating wind speed. The low frequency components of the fluctuating wind speeds mainly contribute to the non-zero skewness, while distribution of the high frequency component is found to have high kurtosis values. By further studying the decomposed wind speed, the mechanisms of the non-Gaussian distribution are examined from the phase, turbulence energy point of view.

• Journal of Korean Medical classics
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• v.21 no.2
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• pp.87-99
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• 2008

From pathological view, Gwoleumbyeong(厥陰病) may be explained as extreme reduction of Gwoleumgyeonggi(厥陰經氣) due to immoderate Wihan(胃寒). Also, concerning regions of human body, Gwoleumbyeong has close relation to lower abdomen and genital, which are the origins of Gwoleum meridian[厥陰經]. Therefore, it is appropriate that the nature of Gwoleumbyeong be described as Hangeukyangul(寒極陽鬱), rather than Sangyeolhahan(上熱下寒), Hanyeolchakjap(寒熱錯雜). Sangyeolhahan, Hanyeolchakjap does not represent Gwoleumbyeong to the full extent, in a sense that the term views Hanyeol(寒熱) as two equal rank, whereas pathogenesis of Gwoleumbyeong depends on the sole extremity of Wihan(胃寒). The reason that the nature of sanghallon(傷寒論) be regarded as Sangyeolhahan, Hanyeolchakjap has been lying on the presupposition that whole symptoms of Hangwol (寒厥), Yeolgwol(熱厥), diarrhea[下利], vomiting[嘔吐] and hiccup, from "Gwoleumpyeon(厥陰篇)",may be categorized into Gwoleumbyeong. However, the symptoms described above do not show Gihwa(氣化) characteristic of Gwoleum(厥陰) and follow the regional distribution of Gwoleumbyeong, from which it can be pointed that those symptoms have no relation with Gwoleumbyeong. Ever since the theory of Yukgigihwa(六氣氣化) was used to comprehend and interpret "Sanghallon", Gwoleumbyeong has been thought as equivalence of Gwol(厥), which led to misunderstanding of Sangyeolhahan, Hanyeolchakjap. However, Gwoleumbyeong from "Sanghallon" has been argued in specific, through the historical practice of Sanghan(傷寒) as pathogen, particular state of meridian and correlation of meridian and Byeongjeung(病證).

• Journal of Contemporary Eastern Asia
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• v.14 no.2
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• pp.5-15
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• 2015

A growing number of studies have examined the relevance and impact of social media in building organizational resilience, which the ability to recover from a crisis, in the field of emergency management. However, few studies have assessed how these emergency response organizations perceive their own use of social media in crisis situations. In attempting to fill this gap, this study conducted a structured survey with emergency-response organization representatives in Seoul, South Korea, to examine how such organizations evaluate their utilization of social media in an urban emergency situation and how their social media uses are related to promoting organizational resilience during adverse events such as a flood. Overall, the findings imply that organizations are not yet taking full advantage of social media. Respondent evaluations of their own social media use in all three assessment areas-information provision, information dissemination, and emotional messages-were not satisfactory. However, their perceptions of how well they utilize social media were positively related to how they view their organizational resilience. Therefore, it may be that these organizations realize the powerful role of social media in building organizational resilience but lack the knowledge and experience to make the best use of social media services.

• Journal of Power Electronics
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• v.2 no.3
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• pp.181-188
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• 2002

The utility interfaced sinewave modulation Inverter for the solar photovoltaic power conditioner with a high frequency transformer is presented for residential applications. As compared with the conventional full-bridge hard switching slnewave PWM inverter with a high frequency link, the simplest single-ended edge-resonant soft switching sinewave inverter with a sinewave duty cycle pulse control scheme is implemented, resulting in size and weight reduction, low cost and high efficiency This paper presents a prototype system of the sinewave zero voltage soft switching sinewave inverter for solar power conditioner, along with its operating principle and unique features. In addition to these, this paper discusses a control implementation to deliver high quality output current. Major design of each component and the power loss analysis under actual power processing is also discussed and evaluated from an experimental point of view A newly developed utility-connected sinewave power conditioning circuit which achieves 92.5% efficiency under 4kW output is demonstrated.