• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.459-460
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• 2011

한전의 가공 송전선로는 2010년 기준으로 약 12,990km(765 kV 송전선로 354 km, 345 kV 송전선로 약 3,868 km, 154 kV 송전선로 8,173 km, 66 kV 송전선로 : 약 595 km)가 설치되어 운전되고 있다. 이러한 송전선로는 평지, 구릉, 산악지 등에 설치됨으로써 자연환경에 크게 영향을 받는다. 특히 전 세계적으로 낙뢰에 의한 송전선로의 트립 고장이 전체 고장의 약 60%를 점유하는 것으로 보고되고 있으며, 낙뢰에 의한 고장을 최소화하기 위한 내뢰 설계를 시행하고 있다. 한전에서도 전압별 계통의 신뢰도와 경제성을 고려하여 765 kV 송전선로의 목표 사고율은 0.35[건/100 km 년], 345 kV 송전선로의 경우는 1.0[건/100 km.년], 154 kV 송전선로의 경우는 2.0[건/100 km 년] 이하의 목표 사고율을 설정하여 설계 운영하고 있다. 그러나 2000년 이후 낙뢰발생 빈도가 증가하고 있으며, 낙뢰에 의한 고장 점유율도 약 75%로서 고품질 전력공급을 위한 내뢰 대책 수립의 검토가 요구되고 있다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.541-542
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• 2011

한전의 가공 송전선로는 2010년 기준으로 약 12,990km(765 kV 송전선로 354 km, 345 kV 송전선로 약 3,868 km, 154 kV 송전선로 8,173 km, 66 kV 송전선로 : 약 595 km)가 설치되어 운전되고 있다. 이러한 송전선로는 평지, 구릉, 산악지 등에 설치됨으로써 자연환경에 크게 영향을 받는다. 특히 전 세계적으로 낙뢰에 의한 송전선로의 트립 고장이 전체 고장의 약 60%를 점유하는 것으로 보고되고 있으며, 낙뢰에 의한 고장을 최소화하기 위한 내뢰 설계를 시행하고 있다. 한전에서도 전압별 계통의 신뢰도와 경제성을 고려하여 765 kV 송전선로의 목표 사고율은 0.35[건/100 km 년], 345 kV 송전선로의 경우는 1.0[건/100 km 년], 154 kV 송전선로의 경우는 2.0[건/100 km 년] 이하의 목표 사고율을 설정하여 설계 운영하고 있다. 그러나 2000년 이후 낙뢰 발생 빈도가 증가하고 있으며, 낙뢰에 의한 고장 점유율도 약 75%로서 고품질 전력공급을 위한 내뢰 대책 수립의 검토가 요구되고 있다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.36-41
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• 2009

This paper presents the development of a micro punching system with modified cymbal mechanism. To realize the micro punching, we introduced the hybrid system with a macro moving part and micro punching part. The macro moving part consists of a ball screw, a linear guide and the micro step motor and micro punching part includes the PZT actuators and displacement amplification device with modified cymbal mechanism. The PZT actuator is capable of producing very large force, but they provide only limited displacements which are several micro meters. Thus the displacement amplification device is necessary to make those actuators more efficient and useful. For this purpose, a cymbal mechanism in series is proposed. The finite element method was used to design the cymbal mechanism and to analyze the mode shape of the one. The displacement and mode shape error between the FEM results and experiments are within 10%. A considerable design effort has been focused on optimizing the flexure hinge to increase the output displacement and punching force.

• Journal of IKEEE
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• v.24 no.3
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• pp.821-827
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• 2020

In particular, vehicles with internal combustion engines of public transportation such as diesel and CNG buses are in urgent need of measures to reduce emissions as they have a long daily total mileage, long driving hours and a large number of vehicles. In this paper, the fuel consumption rate (km/kWh) was actually measured through road test of electric buses. Based on the measured values, CO₂ emissions from internal combustion engines and electric buses were calculated per bus. In addition to environmental improvement effects such as the expected reduction of carbon dioxide compared to CNG buses when replacing city buses with electric buses, additional effects were analyzed when the replacement of CNG buses is expanded to electric buses.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.429-431
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• 2014

Raspberry Pi is in the UK (Paspberry Pi) Foundation created a compact / Cheap PC and was developed as part of the educational project. RCA connection jack and has been released in March 2012 was also sold out in one hour. Raspberry Pi Linux kernel based operating system called Raspberry Pi using optimized Raspbian Debian-based operating systems are often used to be free. Raspberry Pi is currently in the field of IoT with the board quite Cubie limelight and Cubie board holds more data. Arduino is quite easy to reach and access to the avr but impossible to include any custom code associated to a library and customize drawbacks must be solved only. Raspberry Pi using the Raj Caribbean and limitations of low cost, but there is a small output. So, for a combination of the two, with GPOI was reminiscent of hardware control. In this paper, using GPIO Cooking Hacks RaspberryPi board for controlling input and output by using the shield is insufficient expansion raspberry pie was confirmed that the good operation was verified.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.333-342
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• 2013

Soil compaction is affected by soil texture, organic matter (OM), strength (ST) and soil moisture, which is difficult to understand the degree and effects of related factors. The purpose of the study is to assess the impact of them on the compaction with bulk density (BD). The analysis was conducted with data collected from national-wide monitoring sites including 105 upland soils, 246 orchard soils, and 408 paddy soils between 2009 and 2012. The distributions of soil physical properties were measured. The correlation and multi linear regression analysis were performed between soil physical properties using SAS. The regression equation of BD(y) includes ST, gravitational water contents (GWC), and OM as variables commonly, having additional factors, clay content and sand content in paddy soil and upland soil for only subsoil (p<0.001). Our results show that the BD could be explained about 40~50% by various physical properties. The regression was mainly determined by ST in orchard and upland soil and by the GWC in paddy soil. To mitigate soil compaction, it is important to maintain the proper level of OM in upland soil and to consider the moisture condition with soil texture in paddy soil when making work plan. Furthermore, it would be recommended the management criteria classified by soil texture for the paddy soils.

• Tuberculosis and Respiratory Diseases
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• v.74 no.4
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• pp.187-190
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• 2013

We report a rare case of lung disease caused by Mycobacterium lentiflavum in a previously healthy woman. A 54-year-old woman was referred to our hospital due to chronic cough and sputum. A computed tomography scan of the chest revealed bilateral bronchiectasis with bronchiolitis in the right middle lobe and the lingular division of the left upper lobe. Nontuberculous mycobacteria were isolated twice from three expectorated sputum specimens. All isolates were identified as M. lentiflavum by multilocus sequence analysis based on rpoB, hsp65, and 16S rRNA fragments. To the best of our knowledge, this is the first documented case of M. lentiflavum lung disease in an immunocompetent adult in Korea.

• Elastomers and Composites
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• v.43 no.3
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• pp.183-190
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• 2008

In this study, we have investigated mechanical properties and scratch resistance of polypropylene compounds by two types of masterbatch with different molecular weight of PP. Masterbatches were prepared with polypropylene(PP) and polydimethylsiloxane(PDMS) by melt mixing. Mechanical properties and scratch behavior were examined with UTM and polarizing microscope. The morphology surface of grain pattern was investigated Color 3D Laser Scanning Microscope. Mechanical properties of two masterbatches containing PP compounds showed a little bit difference in accordance with amount of M/B. Scratch resistance was much improved by adding masterbatches used high-molecular weight PP. Scratch resistance was excellent when grain pattern of the surface is deep, large, round and irregular.

• Elastomers and Composites
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• v.44 no.2
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• pp.156-163
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• 2009

Our objective is to increase the flowability of Polypropylene(PP) compounds and achieve flow mark free surface in injection molded specimen. We have investigated flowabilities of PP compounds which were composed of PP, rubber, talc, and trace amount of additives. Flowability measurement was performed with four types PPs of which molecular weight distributions(MWD) and melt indexes(MI) were different. Rheological properties of the PP compounding materials, such as spiral flow(SF) length, MI, and shear viscosity, were evaluated. When PP with the broad MWD was used, there were remarkable cases where the spiral flow length of low MI PP compound was longer than that of higher MI PP compound. The PP compound having low MI but broad MWD PP has more flowability than the compound with only high MI.

• Journal of Life Science
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• v.16 no.4
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• pp.659-663
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• 2006

The extracts of Plocamium telfairiae using several solvents with different polarities were prepared and their growth inhibitory effects were examined on the human cancer cells. We investigated the cytotoxic effects of P. telfairiae extracts on HT-29 cells by the MTT reduction assay and examining the morphological change under the inverted microscope. Among three extracts, the methanol extract showed the strongest inhibitory effect on the growth of HT-29 cells. The methanol extract was further fractionated sequentially with n-hexane, diethyl ether, ethyl acetate, and aqueous for purifying crude methanol extract. The n-hexane layer among the fractioned layers showed remarkable inhibitory activity on the growth of HT-29 cells. Moreover n-hexane layer showed the notable growth inhibition effects with a dose-dependent manner against SW620, HeLa, and MCF-7 cells as well as HT-29 cells. These results indicated that P. telfairiae extracts may be contained bioactive materials with inhibitory effect on the growth of human cancer cells.