• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.1
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• pp.89-97
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• 2003

High frequency common mode voltage produced by PWM inverter fed Induction motor is a major cause of conducted EMI, creation motor ground currents, bearing currents and other harmful products. The zero switching states of inverter control invoke large in comparison with the non-zero switching state of Inverter control. We proposed a common mode voltage reduction method based on sinusoidal PWM technique. PWM signal are generated by comparing respective sinusoidal reference signal with three triangular carrier wave displaced of 120$^{\circ}$. Simulation and experimenta1 result show that common mode voltages in the proposed PWM technique are reduced by approximate 66% more than conventional FWM technique.

• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.170-178
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• 2009

In order to develope a common ground system, a general procedure language that can be used in both EGSE and MCS is primarily needed. As the first step in developing a common test and integration procedure language, KARI's ATS for AIT and MCE for GS were compared to some of the most representative languages such as PLUTO regarded European standard, STOL and ELISA and PIL. Based on the analysis, design features of developing a common test and integration procedure language were presented.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2149-2151
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• 1999

This paper describes the impulse response characteristics of the grounding systems in power utility system. Several regulations regarding to electric power equipments, services and managements require that the groundings of class 1 ($E_1$) and class 2 ($E_2$) must be connected at the common point in grounding systems. In addition, the grounding for arrester ($E_{LA}$), which belongs to the grounding of class 1, should be connected at the same point. However, there is no method and position of common-connection at anywhere. In this work, when the impulse current was injected through the grounding conductor for arrester, the investigations measuring and analyzing potential rises induced at the common connection point and other grounding conductors were conducted. The experiments were carried out in the conditions of the grounding conductor of 25m long and the near or remote common connection from ground electrode. The lightning impulse current was applied so as to simulate the on-set of arrester due to lightning and/or switching surges.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.167-174
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• 2016

The Korean distribution line currently consists of overhead ground wires (OHGW), overhead distribution lines, neutral wires (NW), and messenger wires (MW). The MW is installed under the NW. The lightning protection system in Korea is focused on OHGW and lightning arrester and the MW are not considered. Therefore, this paper proposes the applicability of MW for purpose of lightning protection. For this, we analyzed the effects of lightning overvoltage according to the existence of OHGW and MW and the grounding conditions of the MW in the Korean distribution system. The grounding conditions of the MW that we took into consideration were the common or separate grounding of the MW and NW. The analysis based on the equivalent circuit of the distribution pole at each condition was performed. The distribution lines and lightning were modeled using the Electromagnetic Transients Program (EMTP). For each of the installation conditions of the OHGW and MW, the various lightning conditions were simulated and analyzed for both direct and indirect lightning. The simulation results showed that, if the OHGW was not installed in the Korean distribution system, the lightning overvoltage could be reduced by the common grounding of the MW and NW.

• Journal of The Korean Digital Architecture Interior Association
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• v.13 no.4
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• pp.13-23
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• 2013

Steven Holl is outstanding architect who has been applied his phenomenological thinking to his works. he has been reported that he had adhered to focus his interest on coherent phenomenological theme and sublimated his architectural concept succesfully. This study focuses on relationship how phenomenological concept has common ground with architectural parts and with the study on phenomenological application methodology of architectonics of Steven Holl. In the case of Holl, with the theme of sense and flesh, he molds phenomenologically sensitive space. His works contains coherent phenomenolgical concepts such as distrust of rationality, synthesis of consciousness, and qeustions of perception. The Methodologies of connection with environment(nature or bridge), regional values, placeness, light and time are considered in his works(books and architectural works) as anchoring, interwining and parallax for phenomenological process in his concepts. His methodologies of enlisted works contain many valuable concepts of phenomenological intuition and would be applicable to contemporary and future architecture for humanism.

• Journal of Environmental Science International
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• v.26 no.2
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• pp.173-181
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• 2017

Catch data for the common squid (Todarodes pacificus), classified by squid-jigging fisheries per grid (size: $0.5^{\circ}latitude{\times}0.5^{\circ}longitude$), and the water temperature values KODC (Korea Ocean Data Center) were collected for the 1980-2009 period to study the changes in squid distribution and migration with climate regimes (1980s, 1990s, and 2000s). The primary fishing period in the 1990s and 2000s was approximately 2-3 months earlier than that in the 1980s. Especially in the East Sea, the fishing grounds in the 1980s stayed longer at high latitudes than those in the other decades. Moreover, in the 1980s, centers of the fishing ground were located near the Yamato bank (central East Sea), whereas in the 1990s and 2000s, they were situated near the southeastern coast of the Korean peninsula.

• Hwankyungkyoyuk
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• v.16 no.2
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• pp.29-38
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• 2003

The main purpose of this study is to search a new perspective of environmental education through investigating of alternative education. Environmental education is introduced by needs of society for an effective way of solving environmental problems. But it also has a meaningfulness which is internal need of education for proposing and fostering ecological human corresponds with crisis of modernism. In spite of excessive rhetoric, vision of formal environmental education is very negative. Formal environmental education is restricted to optional course. So, its potential isn't fulfil. Education is both part of the problem and the solution. Education is proclaimed at high level as the key to a more sustainable society and yet it daily plays a part in reproducing an unsustainable society. If environmental education is to fulfil its potential as an agent of environmental problem solution, it becomes both part of the ideal and the practice of education. In this point, alternative education is a model of what environmental education ought to be. Environmental education and alternative education have a common ground in end of education and critical position to the modern education system.

• The Journal of Korean Medicine
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• v.28 no.1 s.69
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• pp.171-186
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• 2007

Objective : No studies had been carried out to date on how Korean medicine practitioners recognize and treat postpartum diseases. Therefore, research on such issues by means of a questionnaire survey was expected to contribute to providing common ground and foundation far postpartum treatment. Methods : This study is based on a questionnaire survey administered to 200 doctors, consisting of 79 members of the Korean Society of Oriental Obstetrics & Gynecology and 121 Korean medicine practitioners, from May to September 2006. Items related to individual characteristics of Korean medicine practitioners and 20 objective items constituted the questionnaire, with every item of the questionnaire belonging to 6 greater categories that the author had categorized for the purpose of the study. Results : The result of the study showed what perspectives and clinical attitudes the majority of participating Korean medicine practitioners had in relation with postpartum diseases. On the basis of these findings, better common ground and systematic treatments can be developed to treat postpartum diseases.

• Journal of Ecology and Environment
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• v.45 no.2
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• pp.78-87
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• 2021

Background: To understand shade and wind effects on seedling traits of common reed (Phragmites australis), we conducted a mesocosm experiment manipulating day length (10 h daytime a day as open canopy conditions or 6 h daytime a day as partially closed canopy conditions) and wind speed (0 m/s as windless conditions or 4 m/s as windy conditions). Results: Most values of functional traits of leaf blades, culms, and biomass production of P. australis were higher under long day length. In particular, we found sole positive effects of long day length in several functional traits such as internode and leaf blade lengths and the values of above-ground dry weight (DW), rhizome DW, and total DW. Wind-induced effects on functional traits were different depending on functional traits. Wind contributed to relatively low values of chlorophyll contents, angles between leaf blades, mean culm height, and maximum culm height. In contrast, wind contributed to relatively high values of culm density and below-ground DW. Conclusions: Although wind appeared to inhibit the vertical growth of P. australis through physiological and morphological changes in leaf blades, it seemed that P. australis might compensate the inhibited vertical growth with increased horizontal growth such as more numerous culms, indicating a highly adaptive characteristic of P. australis in terms of phenotypic plasticity under windy environments.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.384-388
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• 2004

High frequency common mode voltage produced by power inverters are a major cause of conducted EMI, creating motor ground currents, bearing currents and other harmful by products. This paper focuses on a new SVPWM method with random PWM injection to reduce conducted EMI noise. A New PWM technique associated with the common mode voltage can be significantly reducing and contributes to mitigate. The common mode voltage to $50\%$ in comparison with that for conventional SVPWM technique. Validation of the theory and reduction methods are then performed experiment ally based on an induction motor drive.