• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.7
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• pp.329-333
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• 2001

The pulsed poser system has been widely used to many applications, such as E/P(Electrostatic Precipitator), DeNox/DeSOx power system, ozon generator, etc. A pulse energy efficiency for load depends on the rising time, peak value, pulse duration and impedance matching, etc. The pulse generator generally required for short pusle duration and high peak value was forced to consider its volume and economy. In this study, developing a compact pulse generator that applied for cascading method to be made of two pulse transformers, we compared cascading voltage with non cascading one by applying the pulse energy to load. Adopting cascading technique to pulse transformer, we found that average cascading voltage was about 60[%] of theoretical value. Maximum cascading ratio was calculated at 60 times compared with non cascading voltage.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.157-167
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• 2020

The purpose of this study is to analyze the relationship between the occurrence of intermediate peak and time duration, and to conduct a review for the causes of the intermediate peak. In this test, ice impact tests were conducted using a bow side shell frame and ice specimen. A total of 70 samples were manufactured. Two types of ice specimen with relatively different surface conditions were used. The criterion for dividing the two types of ice specimen was the different exposure times to room temperature after freezing. This experiment was conducted for each parameter in order to reproduce the actual icebreaking situation. As a result of the analysis, the intermediate peak in the ice load signal have been found to be caused by mechanisms by which the inner surface of broken ice contact with hull immediately after the initial hitting point of ice has been broken.

• Journal of the Korea Concrete Institute
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• v.25 no.5
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• pp.547-554
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• 2013

This study was intended to estimate the bond strength of steel fiber in UHPFRC through pullout test. The pullout test was carried out with the double-sided pullout specimens with multiple fibers. First, the effect of fiber density on the bond strength was investigated, and the experimental result presented that the density range considered in this study was proved not to produce fiber-to-fiber interaction. The bond strength was estimated from several methods, which are based on the pullout load or energy at peak load, and the total energy absorbed until fibers are pulled out completely. the estimated bond strength obtained from the total energy was shown to be under the influence of the embedded length of fiber. the bond strengths obtained from peak load condition was 6.64 MPa in average, which had little difference compared to 6.46 MPa calculated by peak load only. Considering simplicity of test and analysis, it may be no matter to estimate the bond strength from peak load in pullout test.

• Computers and Concrete
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• v.15 no.4
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• pp.563-588
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• 2015

Piers are the most vulnerable part of a bridge structure during an earthquake event. During Kobe earthquake in 1995, several bridge piers of the Hanshin Expressway collapsed for more than 600m of the bridge length. In this paper, the most important results of an experimental and analytical investigation of ten reinforced concrete bridge piers specimens with the same cross section subjected to constant axial (or variable) load and reversed (or one direction) cycling loading are presented. The objective was to investigate the main parameters influencing the seismic performance of reinforced concrete bridge piers. It was found that loading history and axial load intensity had a great influence on the performance of piers, especially concerning strength and stiffness degradation as well as the energy dissipation. Controlling these parameters is one of the keys for an ideal seismic performance for a given structure during an eventual seismic event. Numerical models for the tested specimens were developed and analyzed using SeismoStruct software. The analytical results show reasonable agreement with the experimental ones. The analysis not only correctly predicted the stiffness, load, and deformation at the peak, but also captured the post-peak softening as well. The analytical results showed that, in all cases, the ratio, experimental peak strength to the analytical one, was greater than 0.95.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.165-168
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• 1995

The recent rapid growth of air conditioning load has become a major reason of peak load increase in summer. In connection with this, we surveyed the load management projects of utilities world-wide and their detailed activities. This study is to develop a remote load control system using computer and radio communications. We finished the field-test of this system on August 1995 in Seoul area. During the field-test, the remote load control of air conditioners was proved to be well-timed. Two control modes, group control and all control, are available for the user to select. The transmission reliability of the load control signal was very good and the functions of system hardware as well as the software were excellent. So we confirmed the applicability of the load control system including the paper communication network. In this paper, detailed information on the system functions and experimental results are described.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.27-34
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• 2014

The paper proposed a sizing method of an energy storage system(ESS) for peak shaving of high-speed railway substations based on load profile patterns of substations. A lithium based battery ESS was selected since it can produce high-power at high speed that peak shaving requires, and also takes up a relatively smaller space for installation. Adequate size of the ESS, minimum capacity which can technically meet a peak shaving target, was determined by collectively considering load patterns of a target substation, characteristics of the ESS to be installed, and optimal scheduling of the ESS. In case study, a local substation was considered to demonstrate the proposed sizing method. Also economic analysis with the determined size of ESS was performed to calculate electricity cost savings of the peak shaving ESS, and to offer pay-back period and return on investment.

• Geomechanics and Engineering
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• v.17 no.3
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• pp.253-259
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• 2019

Concrete-to-concrete bedding planes (CCBP) are observed from time to time due to the multistep hardening process of the concrete materials. In this paper, a series of direct/cyclic shear tests are performed on CCBP under static and dynamic normal load conditions to study the frictional behavior effect by the shear velocities, normal impact frequencies, horizontal shear frequencies, normal impact force amplitudes, horizontal shear displacement amplitudes and normal load levels. According to the experimental results, apparent friction coefficient k ($k=F_{Shear}/F_{Normal}$) shows different patterns under static and dynamic load conditions at the stable shear stage. k is nearly constant in direct shear tests under constant normal load conditions (DCNL), while it is cyclically changing with nearly constant peak value and valley value for the direct shear tests under dynamic normal load conditions (DDNL), where k increases with decreasing normal force and decreases with increasing normal force. Shear velocity has little influence on peak values of k for the DCNL tests, but increasing shear velocity leads to increasing valley values of k for DDNL tests. It is also found that, the valley values of k ascend with decreasing impact normal force amplitude in DDNL tests. The changing pattern of k for the cyclic shear tests under constant and dynamic normal load conditions (CCNL and CDNL tests) are similar, but the peak value of k is smaller in CDNL tests than that in CCNL tests. Normal load levels, shear displacement amplitudes, vertical impact frequencies, horizontal shear frequencies and normal impact force amplitudes have little influence on the changing pattern of k for the cyclic shear tests. The tests of this study provide useful data in understanding the frictional behavior of the CCBP under distinct loadings, and these findings are very important for analyzing the stability of the jointed geotechnical structures under complicated in situ stress conditions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1658-1662
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• 2010

This paper presents an advanced energy saving algorithm in building. It is important to aggregate a various demand side resource which is surely controllable at the peak power time to reduce the energy cost. Previous demand side algorithm appropriate for building is based on peak power. In this paper, we develop the new energy saving algorithm to reduce the quantity of power consumption. The simulation results show that the proposed tem is very effective.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.542-543
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• 2001

The purpose of this article is to search for desirable operational direction and compensation of hydro-power, after considering the electricity restructuring has influence on operation and profit of hydro-power for peak-load.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.91-98
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• 2008

Hypoid gears are widely used in rear drive and 4WD vehicle axles. Investigation of their sensitivity to deflections is one of the most important aspects of their design and optimization procedures. The deflection test is performed in the actual gear mounting using completely processed gear. This test should cover the fun operating range of gear loads from no load to peak load. Under peak load the contact pattern should extend to the tooth boundaries without showing a concentration of the contact pattern at any point on the tooth surface. Transmission error is tested on an axle assembly triaxial real car load condition.