• Journal of the Korea Computer Industry Society
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• v.5 no.9
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• pp.1031-1042
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• 2004

A renewable energy resource data has the characteristic that its measurement value changes every moment. So the amount of primitive data which is produced by the change of time arevast. Therefore researches are needed for the construction of history database which can save and manage vast amount of history information of renewable energy resource data systematically, the estimation system of renewable energy resources. In this paper, to solve these problems, the estimation method of renewable energy resources is suggested. The method makes it possible to estimate momently changing data of the past systematically.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11a
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• pp.25-31
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• 2005

The decommissioning cost estimation is the very essential procedure to establish the decommissioning plans for Nuclear Research Facilities. The cost estimation must be made in accordance with activity phase and facility installations. This paper shows how to configuring the cost items and identifying the effecting cost factors. In the end, these methods will be utilized as a tool and technique to develop the methodology of cost estimation and calculation program.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.322-326
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• 2008

This paper presents an estimation method of small hydro power(SHP) potential using a SHP resource map. As a basic unit of SHP energy potential at a certain area, capacity and annual energy production of unit head was calculated from the catchment area given by a SHP resource map which was established by numerical hydrologic simulation so that a logical and relatively accurate potential estimation was possible comparing with the performance analysis model for SHP sites. The performance characteristics for Samok-Ri site were analyzed, using the SHP resource map and the developed model. It was found that the SHP resource map and the developed model is useful tool to estimate SHP potential.

• Journal of Wind Energy
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• v.14 no.3
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• pp.34-42
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• 2023

The reduction of operation and maintenance (O&M) costs is a critical factor in determining the competitiveness of wind energy. Predictive maintenance based on the estimation of remaining useful life (RUL) is a key technology to reduce logistic costs and increase the availability of wind turbines. Although a mechanical component usually has sudden changes during operation, most RUL estimation methods use the trend of a state index over the whole operation period. Therefore, overestimation of RUL causes confusion in O&M plans and reduces the effect of predictive maintenance. In this paper, two RUL estimation methods (load based and data driven) are proposed for the bearings of a wind turbine with the results of trend classification, which differentiates constant and increasing states of the state index. The proposed estimation method is applied to a bearing degradation test, which shows a conservative estimation of RUL.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1990.10a
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• pp.28-34
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• 1990

Lighting is one of the largest energy, integrated lighting system with daylight and artificial lighting has been suggested. In such system, perimeter zone can be illuminated by daylighting and the deep area of room by artificial lighting. So, the study is to develope estimation nomograph of lighting energy by turnning-off depth and lighting control systems during daytime. For the purpose, energy nomograph has been developed to apply to side-lit office guilding and the use and limitation of the nomograph has been discussed.

• Journal of Hydrogen and New Energy
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• v.27 no.1
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• pp.36-41
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• 2016

The development need of new renewable energy is more and more important to resolve exhaustion of chemical fuels and environmental pollution. Polymer electrolyte membrane fuel cell has been widely studied to the extent that it can be used commercially. But there are many problems to be solved. One of them is to enhance the stability of fuel cell stacks. This paper proposes a new fault diagnosis method using Least Square Method (LSM) which is one of parameter estimation methods. The proposed method extracts equivalent circuit parameters from on-line measurements. Parameters of the circuit are estimated according to normal and abnormal states using simulation. The variation of parameters estimated in each states enables the estimation of state in fuel cells. Thus the LSM presented can be a suitable on-line parameter estimation method in PEMFC.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1498-1502
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• 2007

There have been many different definitions of energy functions as the second statistics of a signal. In this paper, using the higher order differential energy function, we propose an algorithm separating the amplitude and frequency components in a discrete sinusoidal signal. The proposed amplitude and frequency estimation methods have less computational requirement than the existing methods. It also shows large computational advantage over the root mean square (RMS) calculation of a signal. The proposed methods can be used in the detection of abnormal events in signals on the power line. Computer simulations show that proposed frequency estimation method can detect the presence of voltage increase or decrease for a short period of time. Also, the proposed estimation methods have been compared with existing methods in terms of estimation error variance.

• Journal of the Korean Solar Energy Society
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• v.30 no.6
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• pp.95-101
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• 2010

This paper presents performance estimation approach of grid-connected photovoltaic(PV) system to predict energy yield from irradiance to PV system using normalized yield model for changing meteorological conditions. The accuracy and validity of proposed performance estimation method is identified by compared measured with estimated yield using monitored data. These results will indicate that it is useful to estimate various loss factors causing the system performance obstruction and enhance the lifetime yield of PV system.

• New & Renewable Energy
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• v.19 no.2
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• pp.23-30
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• 2023

Vortex-induced vibrations are a type of flow-induced vibrations caused by alternating lift forces. With increasing demand for renewable energy, the application of vortex-induced vibrations to renewable energy has been widely studied. Vortex-induced vibrations for aquatic clean energy (VIVACE) converter is a renewable energy device that generates electricity from rivers or oceans using vortex-induced vibrations. To increase the design life and power harnessing capacity of the VIVACE converter, the estimation of fluid forces due to vortex-induced vibrations is essential. Herein, vortex-induced vibrations were experimentally tested, and their amplitude and frequency response were measured. The amplitude results showed four different branches: initial branch, upper branch, lower branch, and desynchronization range. According to the fluid force coefficient results, the maximum lift coefficient occurred at the upper branch. Additionally, a mathematical model is proposed to estimate fluid forces due to vortex-induced vibrations without using measurement devices. This mathematical model enables the estimation of fluid force coefficients and phase lag using amplitude and frequency response of vortex-induced vibrations.

• ETRI Journal
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• v.35 no.5
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• pp.757-766
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• 2013

This paper deals with the estimation of the time of arrival (TOA) of ultra-wideband signals under IEEE 802.15.4a channel models. The proposed approach is based on a randomness test and consists of determining whether an autoregressive (AR) process modeling an energy frame is random or not by using a distance to measure the randomness. The proposed method uses a threshold that is derived analytically according to a preset false alarm probability. To highlight the effectiveness of the developed approach, simulation setups as well as real data experiments are conducted to assess the performance of the new TOA estimation algorithm. Thereby, the proposed method is compared with the cell averaging constant false alarm rate technique, the threshold comparison algorithm, and the technique based on maximum energy selection with search back. The obtained results are promising, considering both simulations and collected real-life data.