• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.2
• /
• pp.107-113
• /
• 2008

In 22.9[kV]-y distribution systems, underground cables are provided with multiple-point ground in which each coaxial-neutral line of the distribution cable lines(A, B, C phases) is 3-wire common grounded. In the underground cable distribution systems, circulating current flows in the coaxial-neutral lines and its magnitude amounts to about $40{\sim}50[%]$ load currents, even though loads are balanced. Power loss due to the circulating current consequently reaches to about 76[%] total losses occurred in all conductor lines. This power loss provokes additional temperature rise of the underground cable lines and finally results in 20[%] reduction of the current capacity of the cables. This paper presents a new ground method to overcome such a problem. The proposed method eliminates the circulating current flowing in the coaxial-neutral line effectively. Measurement results confirmed from the practical site-test show validity and effectiveness of this research.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.272-272
• /
• 2012

Additional neutral particle analyzer has been installed to investigate the variation of fast ion tails with regard to the line of sight during 2012 KSTAR campaign. The system has the same photo-diode particle detector as previous system [1]. Both newly installed system and previous system modifield for 2012 campaign have two channels. One has a particle stopper transparent to hard X-ray, the other has no one. It will be used to separate the hard X-ray component from total hard X-ray and fast neutral counts. It is expected to measure fast ion tails more clearly through this extended system. A detailed system and calibration result will be presented in the conference.

• Journal of Korean Vacuum Science & Technology
• /
• v.7 no.1
• /
• pp.1-7
• /
• 2003

The pressure distributions in the test stand built for developing KSTAR NBI ion sources were obtained using a network system composed of conductance elements modeling the ion source, the neutralizer, and other beam line components. The allowable regime was defined on the coordinates of the gas supply rate to the ion source and the neutralizer, considering the proper conditions of the three critical parameters, the ion source pressure for good arc discharge, the pressure integral in the neutralizer for sufficient neutralization, and the chamber pressure for minimum neutral beam loss. The neutral beam evolution along the path from the ion source extraction grid to the calorimeter through the neutralizer, the bending magnet and the vacuum chamber was estimated for typical pressure distributions.

• Journal of Korean Ophthalmic Optics Society
• /
• v.6 no.1
• /
• pp.139-144
• /
• 2001

In order to analyze of the color perception Farnsworth Test Panel D-15 in the CIELab color space coordinates, it was measured by the reflectance spectrum of the 380~780nm wavelength regions. The Test Panel D-15 was situated in the near origin point of higher the saturation in CIELab coordinates (a, b). Normal person perceived to the similar color for the color of small color difference, and color deficiency person depended on the confusing color line and the neutral point unconcerned with the color difference. In case of Ptotanopia, Deutrnopia, r-g defect, y-b defect with the color deficiency, the neutral points position (a,b) were each (2.12,1.02), (4.25,2.05), (2.51,0.25), (1.20,-1.10).

• Journal of The Korean Astronomical Society
• /
• v.37 no.4
• /
• pp.193-197
• /
• 2004

Anomalies in the far-infrared [C II] 158 ${\mu}m$ line emission observed in the central one-kiloparsec regions of spiral galaxies are reviewed. Low far-infrared intensity ratios of the [C II] line to the continuum were observed in the center of the Milky Way, because the heating ratio of the gas to the dust is reduced by the soft interstellar radiation field due to late-type stars in the Galactic bulge. In contrast, such low line-to-continuum ratios were not obtained in the center of the nearby spiral M31, in spite of its bright bulge. A comparison with numerical simulations showed that a typical column density of the neutral interstellar medium between illuminating sources at $hv {\~} 1 eV $ is $N_H {\le}10^{21}\;cm^{-2}$ in the region; the medium is translucent for photons sufficiently energetic to heat the grains but not sufficiently energetic to heat the gas. This interpretation is consistent with the combination of the extremely high [C Il]/CO J = 1-0 line intensity ratios and the low recent star-forming activity in the region; the neutral interstellar medium is not sufficiently opaque to protect the species even against the moderately intense incident UV radiation. The above results were unexpected from classical views of the [C II] emission, which was generally considered to trace intense interstellar UV radiation enhanced by active star formation.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.05a
• /
• pp.458-461
• /
• 2009

In 3-phase 4 wire system, appearance of the $3^{rd}$ harmonic current by increasing non-liner load is the one of causes overheating neutral wire of power line, and apparatus. So it is necessary to protect power-factor decreasing by the $3^{rd}$ harmonic, and electric power apparatus, and line safely, in this study, power system accidents caused by the $3^{rd}$ harmonic were investigated, then harmonic components analysis and unbalanced load analysis got accomplished. As result, we proposed the method to protect the power line and apparatus from over-current of neutral line by using the most economic 4-pole low voltage circuit breaker.

• Journal of the Korean Wood Science and Technology
• /
• v.18 no.3
• /
• pp.42-52
• /
• 1990

In this study, thick 24mm glulams were composed of thick. 3, 4, 6, 8mm Larch laminas to study that the theoretical analysis and the experimental analysis regarding the location of neutral axis of the glulams were compared, and to study on the effect of location of neutral axis on mechanical properties of glulam. The variation of location of neutral axis after proportional limit(or elastical limit) was studied to offer basic data to make the better composition method of glulam. The result obtained can be summarized as follows: 1. The theoretical neutral axis was 0.547 in solid wood, and also 0.547 in glulams because glulams were composed of only Larch laminas. 2. In solid wood, the deviation of the theoretical and the experimental neutral axis location was 0.1%, But in glulams, the deviation from-12.2% to + 7.8% showed nonuniform pattern but no large deviation. Because laminas was only of Larch and so the mechanical properties of laminas were monotonous. 3. The neutral axis exerted no influance on the elasticity of glulam, which meaned that the maximum shear strength in the neutral axis showed no influance on elasticity limit. 4. The only minutely lower elasticities of glulam than that of solid wood were shown. This was because of influance of glue lines of glulam on the elasticlties. 5. The failure type of glulam was wholly simple tension failure and the horizontal shear failure near neutral axis was not taken place, which was that glue line was complete in bonding and the strength of the lamina was not various but uniform. 6. The ratio of tension strain($^{\varepsilon}t$) I compression strain($^{\varepsilon}c$) initially showed uniform level After the elasticity limit. the ratio was increased with the flow of time and so the tension strain was more increased than compression strain. So this proved tension lamination technique, which is that the mechanical properties of glulam could be improved, if the lamina of more superior strength would he added on the bottom side of the glulam.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.10
• /
• pp.1523-1527
• /
• 2015

Traction power is supplied by three-phase alternating current of 154 kV power grid and electric trains are operated on single phase feeding system. It becomes important to use all the three phases equally and convert them into two-phase electric power (90 degree phase rotation) for traction supply. This is achieved by special transformer from the adjacent traction substation which is separated by a neutral section. Neutral section locations are in front of the substation and between the two substations. The first stage of the Seoul-Busan high-speed railway, design curve radius is larger than 7,000 m and the greatest slope is 25‰. The railway track conditions are evaluated as good enough to install a neutral section at the first stage, but a few factors of coasting operation of the train should be considered at the second stage of Seoul-Busan high-speed railway. The neutral section was located at Kim-cheon substation, which made some neutral section problems produced by the operating train, and the neutral section was moved about 1.5 km to the south toward Dong Dae-gu station due to the track operation condition. Some of the trains which stopped at the existing Kim-cheon Gu-mi station produced another motor block failure after moving the neutral section. In this paper, power quality, system performance and track condition, etc. are suggested to solve the problems.

• Journal of The Korean Astronomical Society
• /
• v.29 no.spc1
• /
• pp.233-234
• /
• 1996

For obtaining estimates of a total magnetic flux, we propose to use measurements of ${\partial}I/{\partial}{\lambda}$. obtained by a modulation method which is formally identical to Stokes V-parameter measurements. In this case the polarization is not analyzed. It is advisable to use in measurements two parts of the spectral line wing.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1033-1036
• /
• 2002

This paper introduces a control method of series active power filter that compensate harmonic currents and eliminate a neutral line current in 3 phase 3 wire and 3 phase 4 wire power system with harmonic voltage source. These harmonic currents and neutral line current are caused by a nonlinear loads such as diode rectifiers and thyristor converters. Proposed methode extracts a voltage reference directly from performance function without phase transformation. Therefore, the control method is simpler than any other conventional methods. Experimental results for 3-phase 3-wire and 3-phase 4-wire series active power filter system were shown to verify the effectiveness of this control method.