• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.10
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• pp.1190-1197
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• 1999

The management of power factor(PF) in the distribution line is treated according to the measurement a month about the feeder unit at the substation. In Korea, we have not researched into power factor in distribution system due to it's less weight. The reactive power in advanced countries is controlled automatically by the compensative condenser switch on/off under the monitoring. This paper first presents the optimal condenser position and proper capacity by lagrangue factor ${\lambda}_{Q}$ which is the line loss index about reactive power unit. Therefore, the largest ${\lambda}_{Q}$ node is the condenser injection point and we find out the best condenser capacity when the line loss is saturated by the moderation of condenser volume. By this method, we suggest 0.6% uprising PF by injection of 15 kVA condenser. Additionally, PF is analysed into 5 areas; large city, middle city, small city, farm village, fishing village by the use of Power Platform which is classified the same concept of the low load management in KEPCO. Two feeders of each area are selected by the worst results of PF in specified areas.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1077-1092
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• 2007

The structural analysis model for estimate of load carrying capacity of railway bridge on service line is important to determine safety of bridges in service, we need to take response of bridge exactly, applying analysis model similar to the real railway bridge most. Track structure which is to distribute loads and decrease vibrations occurred from running train is constructed on the railway bridges. And it is important factor which should be considered to understand exact dynamic and static responses of bridge. But track structure is currently classified as a none structural members in the structural analysis model for estimating load carrying capacity of railway bridge and not considered in analysis model. That's the reason it is difficult to understand exact behavior of bridges. Therefore, the major objective of this study is to develop an analytical track-bridge model which is similar to real railway bridges considering track structure for safety assessment of railway bridge on service line to be effectively done.

• Journal of Fashion Business
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• v.10 no.6
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• pp.122-130
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• 2006

The purpose of this study is to develop the appropriate brassiere pattern for women. Total of 6 brands with same design and 75A, 80A size brassieres(total 12 brassieres) were compared and analyzed for pattern, cup size and patterns. SPSS 10.1 statistic process was used for data analysis. The outcom of this study is summarized as follows. Total length of brassiere by grade were performed smaller than the standard difference 5cm. For 1/2 front cover length, There were no significant differences between 75 and 80. The reason for lower line of wing is shorter than upper line of wing is because side support is cut side ways considering lower line of wing is sewn more toward front than upper line of wing. Even it is same A cup size most cup related sizes become larger according to underbust comparing with cup capacity, they range from 146.67cc to 172.83cc for same A cups. Among same A cups with difference underbust there was average of 26.16cc differences. For relations of material, sewing technology and expansion rate, all 6 brands had zigzag type sewing for upper line tape. For every 0.3cm height, there were $17{\sim}21$ stitches. When urethane mixture is similar expansion rate is higher while number of 1 inch zigzag are high. For elasticity, zigzag stitch expand side ways for more expansion.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.2
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• pp.214-220
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• 2009

Battery is one of the emergency power and its reliability is a very important to keep up the minimum of building capabilities in case of interruption of electric power. This paper, a comparison was made between three different types of instrument on 30 valve regulated lead acid(VRLA) TYPE 12[V]/100[AH] batteries, and then their indicated measured values(impedance/conductance) were compared with the measured capacity of the battery. As a result, Measured value of instrument is strongly related to battery's capacity in the same group battery and Impedance/Conductance guide line for diagnosis of lead-acid battery's state of health(SOH) is a different from each battery guoup.

• Journal of Korean Society of Transportation
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• v.6 no.2
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• pp.49-56
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• 1988

Alternate use of lane at a signalized intersection is a quite different control of the operation of an intersection. This control introduces a new stop line and signal before the original stop line. All of the lanes between the two stop lines are used for left turn traffic or through traffic at a time. The purpose of the control is increasing the capacity of a n intersection without widening the approach width. this paper contains a study on the condition of a application, the proper distances between the two stop lines, the reasonable offsets(rear) to guarantee clearing the vehicles of previous phase, the comparison of approach capacity between the existing control and this control. The study results reveals that the offsets(rear) are rather stable showing the range(maximum value minus minimum value) of it's value does not exceed 3.6 seconds according to the field data. The approach capacity will be increased by 27%, 43%, 59%, 84% when the distances between the stop lines are 30.0m respectively. The control might have theoretical limitation to operate in practice. So an experimental application of the control at some suitable intersections prior to expanding it.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.854-858
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• 1987

This paper considers impulsive noise which produce burst error in high speed(approx.160Kbps) data transmission like ISDN(Integrated Servise Digital Network) using PSTN(Public Switching Telephone Network). To begin with, we obtains the transfer function of subscriber line to calculate the variation of bandwidth when the gain of receiver is fixed and channel capacity of non-gaussian channel in upper-and lower bound, and evaluates the transmission capability. In this paper compares channel capacity bounds which obtains when probability density function of impulsive noise is Laplacian distribution function with impulsive noise generated by waveform synthesier.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1416-1425
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• 2008

Urban railway carries large numbers of passengers during the rush hour. According to the announcement of Ministry of Land Transport and Maritime Affairs(MLTM), 221% of the congestion rate is reported in the SeoulMetro No.2 outer circle line from sadang to bangbea between eight and nine o'clock in the morning. This study analyzes the cause of the client's dissatisfaction about SeoulMetro such as the train delay, and decides the preference rank of the alternatives for congestion alleviation and enhancement of the transport capacity using Analytic Hierarchy Process(AHP).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.4
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• pp.17-24
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• 2000

To use the power line as the communication channel, we have analyzed channel characteristics with the noise data and signal attenuation levels measured on power lines per loom. In this paper, channel capacities are calculated in the best or the worst case noise states and signal attenuations on power lines for three kinds of network-topologies. Analyzed the channel capacity by the best and worst conditions, we concluded that the serious factors influenceing on the channel capacity are the length from a transmitter to a receiver and the network topology.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.12
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• pp.575-580
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• 2000

Switching of the transmission lines(T/L) is one of the ways for suppressing the short circuit capacity. This paper presents the extended optimal power flow(OPF) to the problem of selecting the T/Ls to be open. The constraints of the short circuit currents within limits are added to the inequalities of OPF. Also, the overload on the other lines due to switching of T/Ls is avoided by the linearized inequalities. The number of the open lines can be minimized by incorporating into the objective function of OPF in order to maintain reliability. The method of an effective calculation of the extended OPF is also proposed in this paper, which makes the two parts decoupled. The one concerning the generation dispatch is solved in the first place by the conventional method. Secondly, the other concerning the line-switching is optimized by the proposed formulation.

• Wind and Structures
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• v.27 no.5
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• pp.325-336
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• 2018

The physical infrastructure of the power systems, including the high-voltage transmission towers and lines as well as the poles and wires for power distribution at a lower voltage level, is critical for the resilience of the community since the failures or nonfunctioning of these structures could introduce large area power outages under the extreme weather events. In the current engineering practices, single circuit lattice steel towers linked by transmission lines are widely used to form power transmission systems. After years of service and continues interactions with natural and built environment, progressive damages accumulate at various structural details and could gradually change the structural performance. This study is to evaluate the typical existing transmission tower-line system subjected to synoptic winds (atmospheric boundary layer winds). Effects from the possible corrosion penetration on the structural members of the transmission towers and the aerodynamic damping force on the conductors are evaluated. However, corrosion in connections is not included. Meanwhile, corrosion on the structural members is assumed to be evenly distributed. Wind loads are calculated based on the codes used for synoptic winds and the wind tunnel experiments were carried out to obtain the drag coefficients for different panels of the transmission towers as well as for the transmission lines. Sensitivity analysis is carried out based upon the incremental dynamic analysis (IDA) to evaluate the structural capacity of the transmission tower-line system for different corrosion and loading conditions. Meanwhile, extreme value analysis is also performed to further estimate the short-term extreme response of the transmission tower-line system.