• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.67-74
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• 2010

Most of domestic low-voltage consumers are supplied from the TN-C system of KEPCO, but their load installations have established according to the national statutory standard for electrical installations based on the TT system. In this work, to propose the proper system earthing arrangements of ensuring the protection of information-technology equipment against lightning surges, the protection performance of TT and TN systems against lightning surges was investigated. As a result, when lightning surge was injected to the neutral line of distribution system, the potential difference between the equipment earth terminal and neutral point of low-voltage mains in a TT system was significantly raised. The TT system is not advised due to the risk of damage to the sensitive computer equipment. Main equipotential bonding is an important requirement for protection of low-voltage installations against lightning surges. The TN system provides the best means to reduce the incoming lightning surges through the neutral line of low-voltage service systems. In addition, It is highly recommended to install the additional earthing at the service position of low-voltage consumers.

• 전기의세계
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• v.18 no.3
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• pp.28-33
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• 1969

1968년 11월 3일 기하여 우리나라 154KV 주간선계통의 중성점접지방식이 종래의 PC접지방식으로부터 직접접지방식으로 전환되었다. 이 결과 계통의 운전면에 있어서는 이상전압상승의 경감, 고속도차단방식의 채용등으로 공급신뢰도가 한층 더 크게 될것으로 기대되고 있다. 주지하는 바와같이 계통의 안정도는 정상(Steady-state) 및 과도(Transient-state) 안정도의 양자로 대별되지만 이중 현단계의 계통운용면에서 특히 중요한 지위를 차지하는 것은 후자의 과도안정도 일것이다. 본문에서는 최근에 한국전자계산소의 전자계산기(FACOM-222)를 사용하여 직접접지방식전환후의 과도안정도를 계산한 해석결과및 앞으로 채용하여야 할 몇가지 안정도증진대책을 간단히 설명하고저 한다.

• KOREAN ASSOCIATION OF OCCUPATIONAL HEALTH NURSES
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• v.19 no.1
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• pp.18-24
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• 2012

동서양을 망라하여 전 세계적으로 비알코올성 지방간(Nonalcoholic fatty liver disease[NAFLD])의 발생률은 증가추세에 있다. NAFLD는 간에 중성지방(triacylglyceride)이 비정상적으로 축적되어 발생하지만, 사람에 따라서는 간조직에 염증반응이 초래되고, 심지어 간경화, 간암으로까지 진행되기도 한다. NAFLD의 원인이 비만, 인슐린내성과 같은 대사증후군과 연관되기는 하지만, 정확한 병리기전은 아직 규명되지 않았다. 따라서, 치료방법도 충분히 개발되지 못하고 있다. 그럼에도 불구하고, NAFLD에 있어 분명한 점은, 예방과 악화방지가 가능하다는 사실이다.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.455-463
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• 2012

In this study, the measurement of physical properties of ethylene oxide-propylene oxide adducted zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle, viscosity and foam stability. Also, the dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which were obtained using zeta potential measurement and QCM (quartz crystal microbalance) experiments. The isoelectric point of DEP-OSA82-AO zwitterionic surfactant determined by zeta potential measurement was close to that obtained by QCM experiment and both results have shown almost the same trend as that determined by the frictional property measured using an automated mildness tester. In particular, it has been observed that DEP32-OSA82-AO and DEP34-OSA82-AO surfactants provide better softening effect at a pH of acidic or neutral condition than at an alkaline condition. This result indicates that both surfactants act as a cationic surfactant at a pH of acidic or neutral condition and thus provide good softening effect during a rinsing cycle in the detergency process.

• Journal of Life Science
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• v.18 no.8
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• pp.1164-1168
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• 2008

We investigated gravitropic responses in the primary root of maize (Zea mays) seedlings which were exposed to salt stress. The maize roots salt-stressed with higher than 100 mM NaCl or KCl started to reveal enhanced gravitropic curvature after 2 hours form the gravi-stimulation. Such a promotion was not caused by sodium phosphate, but invoked by potassium phosphate, indicating the active component is $K^{+}$. Because NaCl increased gravitropic curvature, despite that $Na^{+}$ did not played any role, we evaluated the role for $Cl^{-}$ by comparing the effects of $MgCl_2$ and $MgSO_4$. The enhancement of the curvature only with $MgCl_2$ revealed that $Cl^{-}$ played a role in the gravi-response, indicating the involvement of anion channels. These results suggest that both of $K^{+}$ and $Cl^{-}$ play roles in the regulation of osmosis that is required for cell expansion in gravitropism as well as in nyctinasty and stomatal opening.

• Korean Journal of Cognitive Science
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• v.1 no.2
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• pp.221-239
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• 1989

The purpose of this study was to explore the processing unit in Korean word.Three experiments were conducted to examine this question.Preliminary experiment and Enperiment I were executed to delineate the processing unit in singles syllable word and Experiment 2,for words two or more syllables.The major finding of the preliminary experiment showed that the effect of the consonant type was not significant but that of the letter position was.Reaction time increased as the position of letter increased.The difference in reaction time between the first and the second position was not significant.However,the difference between the second and third was.In the Experiment 1, the effect of the number of letter was significant: reaction time increased as the number of letters increased.The size of the position effect both in the preliminary experiment and Experiment 1was comparable.Result of Experiment 2 was such that regardless of the presence of the final consonant(s),the reaction time incresased linearly as the number of svllables increased from two to four. The findings of the present study suggest that:(1)processing unit in single syllable Korean words is a syllable without the final consonant(s):(2) but in words of two or more syllables,the unit is likely to be a syllable with the final consonant(s).

• Journal of Conservation Science
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• v.21
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• pp.89-100
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• 2007

This study analyze concentration of minor and trace elements on 47 white porcelains excavated from Dudong-ri, Baekryeon-ri, Sachon-ri kilns in Gyeonsangnam-do by NAA(neutron activation analysis) and try to classify the provenance and characteristics according to the analytical result. Each kilns are divided into the group by PCA(principal component analysis) and LDA(linear discrimination analysis) using 17 elements; Ba Ce, Co, Cr, Cs, Dy, Eu, Hf, La Lu, Rb, Sc, Sm, Ta, Th, V, Yb. The contribution elements are Dy, Sm, La, Ce, Lu, Sc. And soft and hard white porcelains are similar with the chemical composition of the use materials therefore the difference of the chemical composition not confirmed a cause. The analytical results of the fine(I) and poor(II) quality white porcelains presume the difference of the povenance of clay materials or the poduction process such as difference purify and additive materials.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.9
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• pp.1-7
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• 2014

Brushless Direct Current(BLDC) Motor is essential to measure a rotor position because of that this motor type needs to synchronize the rotor's position and changeover phase current instead of a brush and commutator used on the existing dc motor. Recently, many researches have studied on sensorless control drive for BLDC motor. The conventional control methods are a compensation value dq, Kalman filter, Fuzzy logic, Neurons neural network, and the like. These methods has difficulties of detecting BEMF accurately at low speed because of low BEMF voltage and switching noise. And also, the operation is long and complex. So, it is required a high-performance microprocessor. Therefore, it is not suitable for a small BLDC motor sensorless drive. This paper presents control methods suitable for economic small BLDC motor sensorless drive which are an improved design of the BEMF detection circuit, simplifying a complex algorithm and computation time reduction. The improved motor sensorless drive is verified stability and validity through being designed, manufactured and analyzed.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.51-54
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• 2009

Total monitoring device of leakage current in transformer can detects the flowing leakage current on the ground wire connected with the neutral point, and that is monitored at real-time by the transfer. If the over-flowing current is detected, Total monitoring device of leakage current in transformer will warn the administrator to prevent electrical accident. In this thesis, we are going to explain about Total monitoring device of leakage current in transformer. Also we measure leakage current and judge safety in customer.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.444-446
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• 2011

3상3선식 2소자 계량방식을 적용하고 있는 154kV 3상4선식 중성점 접지 고압 고객은 상 불평형시 계량오차가 발생하게 된다. 상 불평형시의 3상4선식 정상 계량방식과 3상3선식 계량방식의 계량오차에 대한 기 공개된 시험분석 자료를 기반으로 하여 본 논문에서는 3상4선식 공급선로에서 2소자 계량을 적용하고 있는 3상4선식 고객에 대하여 전력계량의 신뢰도 향상을 위해 제안된 기존의 3상4선식 전력량계를 활용하여 계량 환경을 개선하는 시공기술로서, 설비개선 비용이 거의 소요되지도 않고 무정전 시공과 함께 전력량계의 제작사양을 변경하지 않는 방법으로 계량 정밀도를 개선 할 수 있는 방안에 대한 검증시험과 적용성 분석 등의 개선대책에 대하여 기술한다.