• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1254-1256
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• 2001

This paper composes the Electric Railway System with the common grounding based on the 5-port network model. We compare the magnification ratio of harmonic currents according to locations of RC bank(i.e s/s. sp, and pp). It takes a lot of costs to equip the RC-bank at all location. And it is NOT effective that RC-bank is equipped at S/S. Finally, this paper proposes SP as the optimal site of RC-bank aspect reducing harmonic.

• Electronics and Telecommunications Trends
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• v.19 no.4 s.88
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• pp.119-126
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• 2004

정보통신설비 접지의 기본적인 방법은 각 설비에 대한 접지계통간에 아무런 접속이 되지 않는 것이다. 이것을 독립접지라고 하는데 이렇게 할 경우에 어느 한 접지체로의 이상전류 유입에 따른 대지전위 상승에 의하여 다른 접지체에 상승유도전압(rising potential)이 걸려 해당 설비에 손상을 입힐 수 있으므로 각 접지체간에 적절한 이격거리를 확보해 주어야 한다. 그러나 설치공간상의 제약을 받게 되므로 때로는 접지계통간에 접속시켜 등전위화를 이룸으로써 이상전류 유입에 따른 영향을 배제할 수 있다. 일본의 기술 영향을 받은 우리나라는 오랜 동안 독립접지 방식이 안정된 방법으로 인식되어 공통접지에 대한 우려를 가지고 있다. 본 논문에서는 공통접지가 어떻게 활용될 수 있는지에 대하여 알아보도록 하겠다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.434-439
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• 2010

This study fabricated a simulation facility which reduced the structure of a current distribution line to 50:1 in order to analyze the induced lightning shielding effect of a 22.9kV-Y distribution line according to ground resistance capacity, grounding locations, etc. When installing an overhead ground wire, the standard for grounding a distribution line with a current of 22.9kV-Y requires that ground resistance in common use with the neutral line be maintained less than $50\Omega$every 200m span. The reduced line for simulation had 7 electric poles and induced lightning was applied to the ground plane 2m apart from the line in a direction perpendicular to it using an impulse generator. If induced voltage occurred in the line and induced current flowed through the line due to the applied current, the induced voltage and current of the 'A' phase were measured respectively using an oscilloscope. When all 7 electric poles were grounded with a ground resistance of less than $50\Omega$ respectively, the combined resistance of the line was $7.4\Omega$. When an average current of 230A was applied, the average induced voltage and current measured were 1,052V and 13.8A, respectively. Under the same conditions, when the number of grounding locations was reduced, the combined resistance as well as induced voltage and current showed a tendency to increase. When all 7 electric poles were grounded with a ground resistance of less than $100\Omega$, the combined resistance of the line was $14.9\Omega$. When an average current of 236A was applied, the average induced voltage and current of the 'A' phase calculated were 1,068V and 15.6A, respectively. That is, in this case, only the combined resistance was greater than when all 7 electrical poles were grounded, and the induced voltage and current were reduced. Therefore, it is thought that even though ground resistance is slightly higher under a construction environment with the same conditions, it is advantageous to ground all electric poles to ensure system safety.

• Journal of the Korean Society of Costume
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• v.57 no.1 s.110
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• pp.17-27
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• 2007

The goal of the study was to research how the japanese fashion effects on the japanese fashion's current. This study was processed by the 'wabi', 'sabi', 'tsu', and 'iki' which were the foundation and core of the japanese traditional culture. This study also investigated the japanese style to help the recognizing of traditional design which needed for internationalization and informational periods. The review of related literature is presented under the following headings : (a) japanese culture, (b) japanese beauty, (c) japanese style, (d) japanese fashion designer. Conclusively, Japan complete unique design of world by on the basis of own tradition and beauty of japan which were revealed on the their common daily life. So To help there cognizing of traditional design which needed for internationalization and informational periods, fashion designer of the world must research the meaning of the trend and motive power of the world fashion, base on the cultural back ground of their country. And for this, the grounding educational curriculums for fashion designer include the process which can promote awareness of their country's culture, tradition, and beauty.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.241-247
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• 2014

The voltage source PWM inverter generally used to drive the air conditioning (A/C) fans has been posing a large issue that the bearings in air conditioning fan motors are highly possible to be corroded electrically. Potential difference called shaft voltage is generated between inner and outer rings of the bearings due to inverter switching. The shaft voltage causes bearing lubricant breakdown dielectrically. As a result, bearing current is caused. This current causes the bearing corrosion. In previous work, we demonstrated that the shaft voltage can be reduced by using an insulator inserted between the outer and inner cores of the rotor in an air conditioning fan motor without grounding. This paper proposes the other countermeasure for reducing the shaft voltage in fan motors. The countermeasure which adds a capacitor between the brackets and the stator core is effective even for fan motors with non-insulated rotor. The effectiveness is confirmed by both simulated and experimental results.

• Structural Engineering and Mechanics
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• v.46 no.5
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• pp.629-644
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• 2013

This paper concerns about the raking damages on the ultimate residual hull girder strength of bulk carriers by applying the modified R-D diagram (advanced method). The limited raking damage scenarios, based on the IMO's probability density function of grounding accidents, were carried out by using sampling technique. Recently, innovative method for the evaluation of the structural condition assessment, which covers the residual strength and damage index diagram (R-D diagram), was proposed by Paik et al. (2012). This concept is applied in the present study and modified R-D diagram, which can be considered vessel size effect, is then proposed. Four different types of bulk carrier structures, i.e., Handysize (37K), Supramax (57K), Kamsarmax (82K) and Capesize (181K) by Common Structural Rule (CSR), were applied to draw the general tendency. The ALPS/HULL, intelligent supersize finite element method, was employed for the ultimate longitudinal strength analysis. The obtained empirical formulas will be useful for the condition assessment of bulk carrier structures. It can also cover different sizes of the bulk carriers in terms of ultimate longitudinal strength. Important insights and findings with useful guidelines developed in this study are summarized.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.4
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• pp.195-200
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• 2007

This paper describes the countermeasures for preventing the electric shock which can be occurred in the low-voltage handhole underwater. Low-voltage handholes were designed and made for the test in the testing field. Which were installed 4 cases. a metal handhole cover was employed in case 1; FRP(Fiber glass Reinforced Plastic) handhole cover in case 2; an insulated rubber was put on the joint of the cables in case 3; the exposed conductors(cover, frame etc) were commoned and grounded in case 4. Thus, an ground potential near the low-voltage handhole was measured and evaluated quantitatively for the 4 cases. The measured results show that the potential of case 2.3 were lower than that of case 1 because the insulated rubber and the FRP cover prevented direct contact to the fault point. The case 4 is the lowest among the 4 cases because the common and grounding helps the fault current release into the ground, which makes the ground potential rise lower. As a result, although each case has the defects, these ways can effectively lower the electric shock risk in the low-voltage handhole.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.4
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• pp.280-287
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• 2008

For the reduction of common-mode noise level in Indirect-contact ECG (IDC-ECG) measurement a driven-right-leg grounding method was a lied to the IDC-ECG. Because the IDC-ECG does not require any direct contact between the electrodes and the human skin. it is adequate for un-constraining long-term ECG measurement at home and its various applications are now under development. However, larger 60 Hz noise induced by power line a ears in IDC-BCG than in conventional ECG, that is a restriction of IDC-ECG a application. In this study, the driven-right-leg ground which has been used in conventional direct-contact ECG, was adapted to the IDC-ECG measurement by feedback of the inversion of amplified common-mode noise to the body through the conductive fertile laid on the chair seat By this study, indirect-contact driven-right-leg ground was developed and it was shown to work stably. It was shown that the level of 60Hz power line noise was reduced to about -40 dB when the driven-right-leg gain was 1000. This study shows that we can extend the upper limit of the frequency band of IDC-ECG to 100Hz from 30Hz which is conventional upper limit in IDC-ECG, and we can raise the ground impedance between the body and conductive textile. So it is expected that the application area of the IDC-ECG will be extended by the results of this study.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.130-138
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• 2008

The tendency of lightning surge to propagate is a eared variously depend on the power system and subject equipment of protection. However, looking into the subject equipment with the lightning surge, the invasion route of lightning surge can be divided in between the two lines of power, between the power line and the ground, the power line and the PE conductor, between the neutral line and the ground and the like. In addition, in the event of the communication equipment, there exists the route of lightning surge incoming from between the communication lines, the communication line and the ground in addition to the power lines. In this study, the tendency of propagation of lightning surge penetrated on to the subject equipment is analyzed through the empirical experiment in accordance with the ground method by using the independent ground, common ground and bypass arrester ground for safety improvement in power lines.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.431-436
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• 2009

As the telecommunication lines bring into widespread use, one of the most important aspects related to power distribution systems is effectively to evaluate the effect on the telecommunication lines from power lines. One of the efficient methods to evaluate the effect is to measure the induced voltage of a telecommunication line as a result of a ground-loop. If the power lines cause high induced voltage, the ground reference in the telecommunication lines is no longer a stable potential, so signals may ride on the noise. A ground loop is common wiring conditions where a ground current may take more than one path to return to the grounding electrode at the arrangement between the power lines and telecommunication lines. When a multi-path connection between the power lines and telecommunication line circuits exists, the resulting arrangement is known as a ground loop. Whenever a ground loop exists, there are potential for damages or abnormal operations of the telecommunication lines. The power lines can induce the voltage on the communication line. The effects can be calculated by considering the inductances and capacitances. However, if we assume that there are only power lines, it doesn't have a practical meaning because there are conductors with other purpose in the neighborhood of the lines. If we consider that case, we need more complex system. Therefore we suggest more complex system considering the conductors with other purpose in the neighborhood of the lines. The neutral wires and the overhead ground wires are considered for calculating the induced voltage. We assume that there are the messenger wires beside the power line as a result of increased use of them. The main purpose of this paper is a study on a shielding effect of messenger wires in the distribution lines. EMTP(Electro-Magnetic Transients Program) program is used for the induced voltage calculation.