• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.37-43
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• 2012

Long-term variations in wind speed and capacity factor(CF) on Seongsan wind farm of Jeju Island, South Korea were derived statistically. The selected areas for this study were Subji, having a year wind data at 30m above ground level, Sinsan, having 30-year wind data at 10m above ground level and Seongsan wind farm, where long-term CF was predicted. The Measure-Correlate-Predict module of WindPRO was used to predict long-tem wind characteristics at Seongsan wind farm. Eachyear's CF was derived from the estimated 30-year time series wind data by running WAsP module. As a result, for the 30-year CFs, Seongsan wind farm was estimated to have 8.3% for the coefficien to fvariation, CV, and-16.5% ~ 13.2% for the range of variation, RV. It was predicted that the annual CF at Seongsan wind farm varied within about ${\pm}4%$.

• 한국태양에너지학회 논문집
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• 제39권4호
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• pp.79-91
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• 2019

The capacity credit (CC) is a key metric for mid- to long-term power system capacity planning. The purpose of this study is to estimate the CCs of domestic wind turbines. Based on hourly capacity factor (CF) data during the seven years from 2011 to 2017, the new so-called probabilistic CF scheme is introduced to effectively reflect the variability of CFs on CC estimation. The CCs are then estimated through the CF-based method and the ELCC (Effective Load Carrying Capability) method reflecting the probabilistic CF scheme, and the results are compared. The results show that the CC value 0.019 for domestic wind turbines proposed in the $8^{th}$ Basic Plan for Electricity Supply and Demand corresponds to the CC with a confidence level slightly lower than 95%.

• 한방재활의학과학회지
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• 제25권1호
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• pp.1-15
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• 2015

Objectives The aim of this study was to investigate the effects of Cannabis Fructus on exercise capacity and cognitive function in chronic hypoperfusion induced vascular dementia rat model. Methods Vascular dementia rat models were induced by chronic cerebral hypoperfusion through bilateral common carotid arteries occlusion (BCCAO). All rats were randomly divided into 4 groups: normal group; control group; CF I group (feeding Cannabis Fructus 100 mg/kg); CF II group (feeding Cannabis Fructus 300 mg/kg). In order to study the effects of oral administration of Cannabis Fructus on vascular dementia rat models, corner turn test, hole board test, radial arm maze test, passive avoidance test were taken and Acetylcholine (ACh) activity, Acetylcholinesterase (AChE) activity, serum of Vascular endothelial growth factor (VEGF) protein level were measured. Also histological findings of the liver, kidney, brain and the change of Tau immunoreactive neurons in hippocampus were observed. Results CF I and CF II showed significant improvement in corner turn test, hole board test, radial arm maze test, passive avoidance test, Acetylcholine (ACh) activity, Acetylcholinesterase (AChE) activity, the serum of Vascular endothelial growth factor (VEGF) protein level and the change of Tau immunoreactive neurons in hippocampus. CF I showed more significant effect than CF II in these tests. However in histological observations of the liver and kidney both CF I and CF II showed glomerular injury and hepatotoxicity. Conclusions These results suggest that Cannabis Fructus was helpful in improving exercise capacity and cognitive function on Chronic hypoperfusion induced Vascular Dementia rats. However Cannabis Fructus affects the liver and kidney, therefore suggest that this is an area for further study.

• Journal of Electrical Engineering and Technology
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• 제7권6호
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• pp.852-858
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• 2012

This paper describes evaluation results of the wind power penetration limit (WPPL) and the wind energy penetration (WEP) in the Mongolian central power system (MCPS). A wind power plant (WPP) in a power system possesses an output power limit because the power system must maintain a balance between the generation and consumption of electricity at all times in order to achieve an adequate level of quality. The instantaneous penetration limit (IPL) of wind generation at a load is determined as the minimum of the three technical constraints: the minimum output, the ramp rate capability, and the spinning reserve of the conventional generating units. In this paper, a WPPL is defined as the maximum IPL divided by the peak load. A maximal variation rate (VR) of wind power is a major factor in determining the IPL, WPPL, and WEP. This paper analyzes the effects of the maximal VR of wind power on the WPPL, WEP, and capacity factor (CF) in the MCPS. The results indicate that a small VR can facilitate a large amount of wind energy while maintaining a high CF with increased wind power penetration.

• 한국태양에너지학회 논문집
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• 제33권6호
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• pp.32-38
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• 2013

In an efforts to encourage renewable energy deployment, the government has initiated so called 1 million green homes program but the accumulated installation capacity of small wind turbine has been about 70kW. It can be explained in several ways such that current subsidy program does not meet public expectations, economic feasibility of wind energy is in doubt or acoustic emission is significant etc. The author investigated annual energy production of Skystream 3.7 wind turbine using measured power curve and wind resource data. The measured power curve of the small wind turbine was obtained through power performance tests at Wol-Ryoung test site. AEP(Annual Energy Production) and CF(Capacity Factor) were evaluated at selected locations with the measured power curve.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.820-826
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• 2014

It is well known that energy generated by a wind generator (WG) depends on the wind resources at the installation site. In other words, a WG installed in a high wind speed area can produce more energy than that in a low wind speed area. However, a WG installed at a low wind site can produce a similar amount of energy to that produced by a WG installed at a high wind site if the WG is designed with a rated wind speed corresponding to the mean wind speed of the site. In this paper, we investigated the power curve of a WG suitable for Korea's southwestern coast with a low mean wind speed to achieve a high capacity factor (CF). We collected the power curves of the 11 WGs of the 6 WG manufacturers. The probability density function of the wind speed on Korea's southwestern coast was modeled using the Weibull distribution. The annual energy production by the WG was calculated and then the CFs of all of the WGs were estimated and compared. The results indicated that the WG installed on the Korea's southwestern coast could obtain a CF higher than 40 % if it was designed with the lower rated speed corresponding to the mean wind speed at the installation site.

• 한국토양비료학회지
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• 제6권1호
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• pp.29-31
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• 1973

Upon the assumption that the available components in the soil evaluated by present analytical procedures, are as effective as the components applied to the soil as fertilizer, some formulas for the calculation of fertilizer requirements (F. R) for crops are suggested. Basically, the formulas are derived by combining the country average values of soil test data(${\overline{ST}}$) and of the optimum rate of fertilizers (ORF) for crops obtained from N.P.K. trials in farmer's field, as following. $$F.R(kg/10a)={\overline{ST}}(kg/10a)+ORFkg/10a-ST(kg/10a)$$ where, ST denotes the available components tested in the soil under question. Although this formula can be used both for P and K fertilizers, considering the significance of the potassium saturation rate of the soil for the availability of K, for the calculation of K fertilizer requirement, following formula is suggested. $$F.R(kg/10a)=(C.E.C.{\times}B.S.R.K.-KST(me/100g){\times}CF$$ where, B. S. R. K. is the basic potassium saturation rate of the soil and CF is conversion factor for the conversion of K me/100g into $K_2O$ kg/10a. The B. S. R. K. for different crops are obtained from the country average values of soil exchangeable K (${\overline{KST}}$), cation exchange capacity (CEC) and the optimum rates of K fertilizers for crops (ORF $K_2O$). $$B.S.R.K.=\frac{{\overline{KST}}{\times}CF+ORF(K_2O)}{CEC{\times}CF}$$ Using these formulas, equations for P and K fertilizer requirements for rice, barley, wheat, corn, italian millet, soy bean, sweet potato, potato and rape are derived.

• Journal of Electrochemical Science and Technology
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• 제10권1호
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• pp.55-60
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• 2019

Herein, the effect of counter anions on the formation of a solid electrolyte interphase (SEI) in a propylene carbonate (PC)-based electrolyte solution was investigated. Although the reversible capacities were different, reversible intercalation and de-intercalation of lithium ions occurred in the graphite negative electrode in the PC-based electrolyte solutions containing 1 M $LiClO_4$, $LiPF_6$, $LiBF_4$, and $LiCF_3SO_3$ at low temperature ($-15^{\circ}C$). This indicated that the surface films acted as an effective SEI to suppress further co-intercalation and decomposition reactions at low temperature. However, the SEIs formed at the low temperature were unstable in 1 M $LiPF_6$ and $LiBF_4/PC$ at room temperature ($25^{\circ}C$). On the other hand, increasing reversible capacity was confirmed in the case of $LiCF_3SO_3/PC$ at room temperature, because the SEI formed at the low temperature was still maintained. These results suggest that counter anions are an important factor to consider for the formation of effective SEIs in PC-based electrolyte solutions.

• 풍력에너지저널
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• 제14권3호
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• pp.54-60
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• 2023

In order to reveal the levelized cost of energy (LCOE) of Korean and foreign wind turbines, a study was conducted for Korean onshore wind farms. Actual CapEx and OpEx data were obtained from audit reports for 26 onshore wind farms corresponding to 53.87 percent of the total onshore wind farms in Korea in the Data Analysis, Retrieval Transfer (DART) system. In addition, capacity factor (CF) data were calculated from data provided by Statistics Korea. Random numbers were generated from distributions that were fitted by the datasets, which were used as input data to perform a Monte Carlo simulation (MCS). The levelized fixed cost (LFC) and the levelized variable cost (LVC) were calculated from distributions of the CapEx, the OpEx and the CF. As a result, the LCOEs of the analyzed total Korean wind farms, and Korean and foreign wind turbines were 147, 148, and 146 USD/MWh, respectively. The averaged LCOE of Korea was estimated to be 4 USD/MWh lower than that of Japan, while it was much higher than German and global averages.

• 한국전자파학회논문지
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• 제16권11호
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• pp.1059-1066
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• 2005

본 논문은 피드포워드 전력 증폭기의 효율 개선을 위한 도허티 증폭기의 적용에 관한 연구이다. 성능 분석을 위하여 중심 주파수 2.14 GHz의 WCDMA 4FA신호를 인가하여 평균 출력 전력 15 W에서 측정하였다. 적용한 도허티 증폭기는 동급 class AB 증폭기와 비교하여 고효율 저선형성의 특성을 나타내며 효율 개선을 위하여 피드포워드 전력 증폭기(FPA)의 주 증폭기로 사용되었다. 특성 변화를 분석하기 위해 선형성과 효율 특성이 다른 2가지 종류의 도허티 증폭기를 적용하였으며 각각의 FPA들은 평균 출력 15 W에서 효율은 $2\%$ 이상의 개선을 보였지만 선형성은 1.5 dBc 이상 저하되는 특성을 나타냈다. 저하된 선형성을 개선하기 위하여 부가적으로 오차 루프의 결합 계수(CF)와 오차 증폭기의 용량을 변화시켰다. CF와 오차 증폭기의 용량 변화로 효율 개선과 높은 선형성을 얻을 수 있었고 도허티 증폭기가 35 dBc 이상의 선형성을 유지하면 부가적인 변화 없이 평균 출력 전력 15 W에서 $2\%$ 이상의 효율 개선과 충분한 선형성을 얻을 수 있다.