• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1682-1687
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• 2016

Approximately 520thousand elevators are operating now in Korea, about 40% ~ 60% of the elevator power is generated. In this paper, by using the method of adding regeneration power of the elevator to the grid-tied photo voltaic inverter, PV generation that was dependant on the solar radiation was significantly improved. In order to confirm this, the regeneration power of the elevator has been simulated in 12% of the rating load, and measured the regeneration power of the elevator in the actual condition to assess the differences of it. The 5[kW] hybrid grid-tied photo voltaic invertor has been fabricated to conduct an experiment for the confirmation of the proposing method. The effectiveness of the proposing method has been reassured with the result of experiment that include the transfer interface part of the regeneration power of the elevator.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.18-23
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• 2010

As the increasing of Non-linear load, we have been growing interest for the harmonics. Harmonics has been focused on the current component rather than voltages. Voltage harmonics can be mainly generated at the PCC with non-linear load and act on voltage unbalance. Voltage harmonics can be enlarged at the capacitor with low impedance as frequency increases. Capacitor is basically used for the power-factor compensation and sometimes as the passive filter. Small voltage of low-order acts on quite a few at the capacitor by the current increase. Capacitor has easily fall under by harmonic components. In this paper, we measured the magnitude and phase angle of asymmetrical voltage with harmonics components at the PCC and calculated with the same condition. we concluded that voltage harmonics of higher order increase each current component but have a little effect on capacitor rating.

• Journal of the Korean Society of Safety
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• v.19 no.4 s.68
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• pp.8-13
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• 2004

The purpose of this paper is to investigate the welding residual stress distribution according to the constraint or non-constraint welding condition with titanium commonly using power station, aircraft, and ship. The measuring method of the residual stress was applied stress release rating method with strain gages and a potable strain meter. The x direction residual stress generally showed the tensile residual stress in case of res03int welding. On the other hand, the x direction residual stress under non-restraint welding were changed tensile stress into compressive stress on 15mm away from welding bead center. Also, the y direction residual stress generally showed the tensile residual stress in case of non-restraint welding and the y direction residual stress under restraint welding were changed tensile stress into compressive stress about 60mm away from welding bead center.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.737-744
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• 2000

This paper resorts to rock mass rating and rock mass quality to draw value based on the evaluation of rock and to draw interrelation formula in relation to rock mass quality, A comparative analysis was given of survey values reported in the existing documents. This paper has tried to find out the relationship between RMR and Q System for the sake of choosing rational reinforcing patterns and of the safety of tunnels. The results run as follow: RMR=8.251n(Q)+43.83. This paper has also tried to find out the relationship between RMR and Q System by using Fuzzy Approximate Reasoning Concept. We suggest that those in charge should not depend on a single system only after evaluating the classification of rocks, and compare one result with another for the good of keeping track of the condition of base rocks in a better way.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.04a
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• pp.226-229
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• 2009

Housing Performance Grade Indication System is one of the advanced system which operate globally in three countries. Housing Performance Grade Indication System of the Japan and Korea has points of similarity and distinction according to special situations of own condition and government. The purpose of a study is how characteristics have points of view about background, composition and an outline of the system, indication standard and method, the situation of issue, making progress direction and what is the clear differences. Also, it is to obtain hints for making progress direction of domestic Housing Performance Grade Indication System. The method of study is in parallel with literature survey, also collection through visiting to researcher, operation company, evaluation institution, housing company of the Japan. and to use data as a result of international workshop on November 2008. Because domestic research team is studying about making system and evaluation, revision, this study will make use this data.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.39-40
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• 2005

Photovoltaic Power Generation system occupies an important position as an alternative energy source, converting directly sunlight into electricity,using a photovoltaic cell. The Purpose of this research is to present and confirm the effectiveness of concentration and tracking of sun in photovoltaic power generation. Comparative experiments were carried outwith two rating 75 watt solar modules in $25^{\circ}$ under condition of various times concentration, tracking and plain normal measuring generated voltages, currents and temperatures of back sheet of modules by internet monitoring system to find out which is best in economic sense. The experiments show that output power of concentration and tracking photovoltaic power generation is over 180% more then that of plain normal system.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.470-475
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• 2000

This research covers the resting of precast/prestressed concrete I-Girder bridge. The research was designed to examine processes for improving the condition evaluation and rating of prestressed concrete bridge. To establish procedures that allow for the full utilization of prestressed concrete bridge capacity, a 28-year old sample was loaded to failure in site. The bridge was constructed with 12 spans, and girders of each span were simply supported. At each loading stage, the deflections, reinforcement strains, prestressing wire strains and concrete strains were examined. Failure behavior was analyzed, and failure load was also evaluated. The test results wee compared to the analytical results from the non-linear finite element analysis.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.3
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• pp.302-310
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• 2008

In order to evaluate the nominal rating of breakers in distribution system due to the increased capacity and operating conditions of power transformers in 154 kV substation, the fault currents in distribution system were calculated by the conventional method and simulations of PSCAD/EMTDC program. Consequently, under the condition of the parallel operation of transformers, the fault currents exceed the nominal current of the breakers in some areas. Without NGR at the secondary neutral of the transformer, the current of single line-to-ground fault was bigger than that of 3-phase fault. Therefore, the results clearly show that the measures to limit the fault currents in distribution system are needed when the increased capacity of power transformers is introduced into 154 kV substation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.6
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• pp.342-348
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• 1999

A new welding machine which adopts zero voltage and zero current switching(ZVZCS) full bridge(FB) DC-DC converter is proposed. The proposed ZVZCS FB DC-DC converter uses auxiliary transformer to obtain ZCS for leading leg. It has capability of controlling load current even in short circuit condition and is suitable for arc welding machines. The power rating of the auxiliary transformer is about one 5th to one 10th of the main transformer. Experimental results for 10KW prototype are shown to verify the principle of operation.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.24-26
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• 1999

In this paper, the conceptual design and FE analysis results of salient pole type alternator under no load condition are described. The designed alternator's rating is 180kW, 3-phase, 4pole, 380/220V, 0.8pf, 60Hz. The conceptual design is described by the process of designing the armature, field, and obtaining some of equivalent circuit parameters. The comparison of FE analysis to the designed results of alternator's output voltage value shows a good agreement.