• Journal of Wind Energy
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• v.13 no.2
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• pp.13-22
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• 2022

In this study, the resonant motion of a floating offshore wind system due to negative damping was mitigated by peak shaving algorithms of the NREL ROSCO controller, and the decreased gains of the blade pitch controller by the gain detuning method for the floating system was increased to the gains of onshore baseline controller to improve the power performance of the turbine. To check the performance of the controller, the dynamic responses between the existing gain-detuned pitch controller and the ROSCO controller with peak shaving control for an OC4 floating offshore wind system were compared. As a result of DLC1.1 at near-rated wind speed, when peak shaving was applied, the average generator power decreased by 1.9%, but it was confirmed that the standard deviation was reduced and stability was improved with fast pitch regulation. In addition, since peak shaving reduces the maximum thrust of the rotor, was confirmed that not only are the loads of the blades and tower reduced, but the surge motion of the floater is also reduced, and the tension of the mooring lines is reduced.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.9
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• pp.20-27
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• 2014

The power consumption pattern of high-speed railway has rarely during night time. But, during service time, the power is consumed irregularly related to train operation. Especially certain unusual about 1-2 days of service time interval to indicate the power consumption is rapidly growing phenomenon, which causes the capacity of the power contract is the annual electricity bill to rise rapidly as the cause. Normally, amount of peak power consumption bill rate at railway substation is over 20% of total electrical bill. Therefore, high-speed railway substation is expected to be considerably larger savings by reducing the peak power of the default charge(demand power).

• Journal of the Korean Society of Physical Medicine
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• v.3 no.4
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• pp.225-233
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• 2008

Purpose : The purpose of this study was to investigate changes of muscle strength, ROM and proprioceptive function as before & after ankle taping in soccer players. For this study fifteen sports club whose had no ankle injuries were volunteered. Methode : Fifteen healthy male in soccer players participated in this study. Biodex pro system3 was used to measure isokinetic muscle strengths at $60^{\circ}$/sec angular velocity. Performances of ankle joint were measured peak torque, total work, average power, total work. To measure proprioceptive function used goniometer. Results : 1. proprioceptive sensation error were significantly differences by before & after taping(p<.05). 2. Compare of total work of dorsi flexion plantar flexion weren't significantly differences by before & after taping(p>.05). 3. Compare of average power of dorsi flexion weren't significantly differences by before & after taping(p>.05). 4. Compare average power of plantar flexion were significantly differences by before & after taping(p<.05). 5. Compare average peak torque of dorsi flexion weren't significantly differences by before & after taping(p>.05). 6. Compare average peak torque of plantar flexion were significantly differences by before & after taping(p<.05). Conclusion : Taping can have propriocetive aberrative angular measure, power & peak torque of plantar flexion were significantly differences. But, total work of dorsi flexion plantar flexion and power & peak torque of dorsi flexion weren't significantly differences.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.8
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• pp.1172-1180
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• 2017

This study analyzed competition in peak load plants between CCGT and GT instead of competition between base and peak load plants like in previous studies. In common overseas power markets, CCGT and GT claim certain market shares as peak load plants with the latter boasting a high utilization rate as reserve plants. In South Korea, however, there has been no introduction of GT in the market that opened in 2001 with no analysis cases of GT's economy as a peak load plant. The current power market of South Korea is run on the cost-based pool, which allows for no price spikes. Since the capacity payment criteria for compensations for missing money are set based on GT generators, the power market uses GT generators as marginal plants. The purposes of this study were to analyze the competitive edge of GT generators as peak load plants in the domestic power market of South Korea and identify the causes of GT's failure in market entry, thus assessing the adequacy of market signals in the domestic power market.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.285-289
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• 2018

In this paper, we demonstrate electromagnetic wave focusing and rectification based on time reversal as a smart method for far-field wireless power transfer. Time reversal in a complex propagation environment allows for transmission of high peak power pulses by focusing the electromagnetic waves selectively regardless of the receiver position. We demonstrate wave focusing and radio frequency (RF) to direct current (DC) rectification via numerical simulation of a complex propagation environment. The results reveal that time reversal can ensure peak power up to 12 dB greater compared to a narrowband continuous wave signal, thereby enhancing the rectified DC voltage with better efficiency.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.348-351
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• 1999

We investigated current limiting properties for an SFCL of YBCO thin film coated with an Au layer. The YBCO film of 1 mm wide and 400 nm thick could carry the current 9.6 A$_{peak}$ without quench. The SFCL limited the fault current below 7.6 A$_{peak}$, which otherwise increases above 65 A$_{peak}$ and melted down at the potential fault current of about 100 A$_{peak}$ which is 10 times greater than the quench current. This means that the Au layer successfully protected the superconducting film by dispersing the heat generated at hot spots and electrically shunting the YBCO film.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.149-152
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• 2001

In this paper, a 1.5V 2㎓ low-power peak detector is presented. Analyzing the designed peak detector circuit which is composed with two NMOSs, two diodes, and two capacitors, the detection characteristic relationships are derived. The simulation results with SPICE for 2㎓ pulse signals and sinusoidal signals on the 1.5V supply voltages show the good detection characteristics for input signal levels of 50㎷~500㎷, and show very small power dissipation of 0.332㎽.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1548-1553
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• 2000

In this paper, an effective peak power reduction scheme for a downlink OFDM-CDMA system is proposed. Using the partial parallel transform(PPT) structure, peak-to-average power ratio(PAPR) can be reduced. The patterns of inputs of Inverse Fast Fourier Transform(IFFT) are more randomized in this structure by allotting the subcarriers to each users. At the cost of complexity we can obtain reduced PAPR and multiple access interference(MA) Computer simulations are carried out from the viewpoint of PAPR and demonstrated the improved PAPR performance.

• Current Optics and Photonics
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• v.5 no.2
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• pp.186-190
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• 2021

In this study, a compact, picosecond, mid-infrared 3.8 ㎛ MgO:PPLN optical parametric oscillator (OPO) laser output with high peak power is realized using a master oscillator power amplifier (MOPA) 1 ㎛ solid-state laser seeded by a picosecond fiber laser as the pump source. The pump source was a 50 MHz and 10 ps fiber seed source. After AOM pulse selection and two-stage solid-state amplification, a 1,064 nm laser output with a repetition frequency of 1-2 MHz, pulse width of 9.5 ps, and a maximum average power of 20 W was achieved. Furthermore, a compact short cavity with a unsynchronized pump is adopted through the design of an OPO cavity structure. When the injection pump power was 15 W and the repetition frequency was 1 MHz, the average output power of idler light was 1.19 W, and the corresponding peak power was 119 kW. The optical conversion efficiency was 7.93%. When the repetition frequency was increased to 2 MHz, the average output power of idler light was 1.63 W, the corresponding peak power was 81.5 kW, and the optical conversion efficiency was 10.87%. At the same time, the output wavelength was measured at 3,806 nm, and the beam quality was MX2 = 3.21 and MY2 = 3.34.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.981-987
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• 2017

In this paper, we estimate the economic benefits of Energy Storage Systems (ESSs) for peak load shaving in an urban railway substation using the annual cost. The annual investment cost of ESSs is estimated using Net Present Value (NPV) and compared with the cost reduction of electricity by the ESS. The optimal capacities of the battery and Power Converting System (PCS) are determined for peak load shaving. The optimal capacity of the ESS and the peak load shaving is determined to maximize the profit by the ESS. The proposed method was applied to real load data in an urban railway substation, and the results show that electric power costs can be reduced. Other aspects of the ESS, such as the lifetime and unit price of the battery, are also investigated economically.