• 전력전자학회논문지
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• 제25권1호
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• pp.1-5
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• 2020

Solar power generation systems require maximum power point tracking (MPPT) control to operate PV panels at their maximum power point (MPP). Most conventional MPPT algorithms are based on the slope-tracking concept. A typical slope-tracking method is the perturb and observe (P&O) algorithm. The P&O algorithm measures the current and voltage of a PV panel to find the operating point of the voltage at which the calculated power is maximized. However, the measurement error of the sensor causes irregularity in the calculation of the generated power and voltage control. This irregularity leads to the problem of not finding the correct MPP operating point. In this work, the power output of a PV panel based on the P&O algorithm is simulated by considering the insolation profiles from typical clear and cloudy weather conditions and the errors of current and voltage sensors. Simulation analysis suggests the optimal control period and perturbation voltage of MPPT to maximize its target efficiency under real weather conditions with sensor tolerance.

• 새물리
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• 제68권11호
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• pp.1215-1224
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• 2018

Most solar photovoltaic (PV) modules frequently get shadowed, completely or partially, resulting in a reduction of PV generation. This paper presents and compares the results from simulations and experimental measurements of the power output from a single PV module under various shading conditions. The study was carried out with a 90 W PV module and a 250 W PV module. The shaded area was increased from 0 to 100% for both variable and constant irradiances to analyze the effect of fluctuations in the solar irradiance certain shading conditions. The effect of shading for irradiance levels from 100 to $900W/m^2$ was investigated. Results showed that for every $100W/m^2$ decrease in the solar irradiance level, the power output decreased by 9, 0.7 and 1.5 W at 0, 25 and 50% shading, respectively. For solar irradiance levels higher than $500W/m^2$, the temperature increased by 1.6, 2.7 and $1.1^{\circ}C$ at 0, 25 and 50% shading, respectively, for every $100W/m^2$ increase in the irradiance.

• 전력전자학회논문지
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• 제27권1호
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• pp.1-8
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• 2022

Recently, photovoltaic (PV) systems have been gradually applied in eco-friendly vehicle applications to improve fuel economy. The relevant market is expected to continue to grow because the installation of large-capacity PV systems to other eco-friendly vehicles, such as electric buses and trains, is being considered. However, in a PV system, power imbalance between submodules and low power generation efficiency occur due to factors such as cell aging, contamination, and shading. To resolve this problem, various differential power processing (DPP) converters have been researched and developed. However, conventional DPP converters suffer from large volume and low efficiency. Therefore, to apply DPP converters to eco-friendly vehicles, increasing efficiency and reducing volume and price compared with existing DPP converters is necessary. In this paper, a novel DPP converter with an integrated transformer is proposed and analyzed. The proposed DPP converter uses a single magnetic component by integrating transformers and secondary sides of conventional DPP converters. Therefore, the proposed DPP converter shows high power density and high efficiency, and it is suitable for PV systems in eco-friendly vehicle applications.

• 식물병연구
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• 제18권4호
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• pp.381-386
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• 2012

독도 생태 연구의 일환으로 2008-2009년 2개년간 독도의 토양을 채집하고 선충의 종류, 밀도, 식이습성군, 생태지수 등의 연구를 수행하였다. 독도에서 총 31종의 선충이 발견되었으며 평균 밀도는 $m^2$당 239,500마리(26,000-836,000)였고 biomass는 $103.9mg/m^2$(3.0-388.6)였다. 중요도는 Acrobeloides 속이 Prominence value(PV) 117.8로 가장 높았고 다음으로 Rhabditidae(PV = 81.9), Prismatolaimus(PV = 39.0), Aphelenchoides(PV = 31.4) 순이었다. Feeding Group별로는 세균성선충이 전체 선충 중에서 밀도로는 77%, biomass로는 62%를 차지하여 가장 중요한 그룹이었고 다음으로는 식물기생성선충과 식균성선충류였다. 동도 참소리쟁이에서 발견된 뿌리썩이선충은 신종으로 추정된다. 독도 선충의 생태적 분석 결과 Shannon and Wiener 지수(2.46), Simpson's diversity 지수(0.86), 종 균일도(0.73), 종 풍부성(1.30)을 볼 때 독도의 선충상은 종이 풍부하고, 다양한 것이 특징이며, 독도만의 독특한 생태계를 유지하고 있다고 하겠고 이것은 경작되지 않고 자연 그대로 보존된 원시적 환경의 특징이다. 이번의 조사 결과는 독도의 생태적 모니터링에 기초자료로 활용되어질 수 있을 것이다.

• 조명전기설비학회논문지
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• 제23권1호
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• pp.162-168
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• 2009

본 논문에서는 태양전지를 가지고 일정량의 태양광으로부터 최대 유효전력을 얻기 위해 고정식 태양광 발전시스템과 태양 위치추적기를 부착한 태양광 발전시스템에서 PV모듈의 각도 변화 및 어레이 간격에 따른 최적의 발전효율에 대한 연구 및 실험을 하였다. 먼저, PV 모듈의 다양한 각도를 가지고 실험한 결과 PV 모듈 경사각 30[$^{\circ}$]에서 측정한 결과 값이 경사각 20[$^{\circ}$] 및 40[$^{\circ}$]일 때보다 발전 효율이 $12{\sim}17$[%] 상승되었다. 그러므로 본 논문의 연구 결과에서는 태양광 발전시스템의 실용화 측면에서 PV 모듈의 경사각 30[$^{\circ}$] 설치를 하여 발전을 하는 것이 가장 좋은 변환 효율을 얻을 수 있었다. 하지만 태양전지를 지붕 및 옥상에 설치를 할 경우, 면적 활용이 좁고 겨울에 눈이 쌓이게 될 경우에는 경사각에 의해 빠르게 쓸려 내려갈 수 있도록 경사각을 35[$^{\circ}$]로 선정하는 것이 타당하다.

• Journal of Power Electronics
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• 제10권1호
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• pp.9-13
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• 2010

This paper proposes an input-series-output-parallel connected ZVS full bridge converter with interleaved control for photovoltaic power conditioning systems (PV PCS). The input-series connection enables a fully modular power-system architecture, where low voltage and standard power modules can be connected in any combination at the input and/or at the output, to realize any given specifications. Further, the input-series connection enables the use of low-voltage MOSFETs that are optimized for a very low RDSON, thus, resulting in lower conduction losses. The system costs decrease due to the reduced current, and the volumes of the output filters due to the interleaving technique. A topology for a photovoltaic (PV) dc/dc converter that can dramatically reduce the power rating and increase the efficiency of a PV system by analyzing the PV module characteristics is proposed. The control scheme, consisting of an output voltage loop, a current loop and input voltage balancing loops, is proposed to achieve input voltage sharing and output current sharing. The total PV system is implemented for a 10-kW PV power conditioning system (PCS). This system has a dc/dc converter with a 3.6-kW power rating. It is only one-third of the total PV PCS power. A 3.6-kW prototype PV dc/dc converter is introduced to experimentally verify the proposed topology. In addition, experimental results show that the proposed topology exhibits good performance.

• 식물병연구
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• 제26권1호
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• pp.44-47
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• 2020

국내에서 분리된 키위 궤양병 원인균인 Pseudomonas syringae pv. actinidiae 균주들에서 스트렙토마이신 저항성 균주가 확인되었다. 2008년부터 2017년 사이에 키위 궤양병이 발병한 111개 과수원에서 분리된 734개 균주의 스트렙토마이신 저항성을 조사하였다. 각 균주의 생존 여부는 100 ㎍/ml의 스트렙토마이신 배지에서 검정하였다. 734개 균주들 중에서 9개 과수원에서 분리된 총 38개 P. syringae pv. actinidiae 균주가 저항성을 나타내었다. Biovar 2에 속하는 저항성 균주들의 경우 몇 개의 특정년도에 발견된 반면, biovar 3에 속하는 저항성 균주들은 2016년 이후에만 발견되었다. 따라서, 키위 궤양병 방제용으로 스트렙토마이신 사용 시 주의해야 하며, 만일 사용하려면 사용 전에 항생제 감수성 테스트가 필요하다.

• 한국식품영양학회지
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• 제31권1호
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• pp.202-211
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• 2018

This study was conducted to develop a salad dressing using Prunella vulgaris L. (PV) extracts. In addition, the study was also aimed at evaluating the quality characteristics of the salad dressing containing various amounts of PV extracts. Salad dressing was prepared by adding 0% (PD-0), 9.4% (PD-20), 18.8% (PD-40), 28.2% (PD-60), 37.6% (PD-80), 47.0% (PD-100) of PV extract. The quality characteristics (sugar contents, salinity, color value, total phenol contents, total flavonoid contents, DPPH, ABTS+ radical scavenging activities, and sensory acceptability) of the dressing were analyzed. According to the results of the study, the sugar contents and salinity of salad dressing increased according to the added amount of PV extract (p<0.001). The color values of lightness and yellowness of salad dressing increased according to the added amount of PV extract, whereas color value of redness decreased (p<0.001). Antioxidant activities were improved depending on the amount of PV extracts (p<0.001). The sensory acceptability (flavor, medicinal flavor, saltiness, sourness, bitterness and viscosity) were significantly higher in the dressing added with 18.8% PV extracts than in the other samples. Based on this result, a storage experiment was conducted by comparing PD-40 and PD-C. After 4 weeks of storage at $4^{\circ}C$ and $24^{\circ}C$, the quality characteristics were observed and the pH was increased in the later stages of storage (p<0.05). The depicted that, viscosity increased with storage time at $4^{\circ}C$ (p<0.001). General bacteria and coliform were not detected during storage. These results indicated that salad dressing with the addition of 18.8% PV extracts has the best quality.

• 한국공간구조학회지
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• 제9권1호
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• pp.6-9
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• 2009

• 한국태양광발전학회지
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• 제6권1호
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• pp.8-20
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• 2020

Nepal has huge potential of hydro and other renewable energy resources including solar energy. However, only 70% of the total population have access to electricity despite the long history of hydropower development in the country. Still more than 37% population in rural areas and around 73% population in Karnali Province, one of the least developed provinces, are living without access to electricity despite taking several initiatives and implementing various policies by government supporting electrification in off-grid rural areas. Government together with donors and private sector has extensively been promoting the off-grid solar photovoltaic (PV) echnology in un-electrified areas to increase electricity access. So far, more than 900,000 households in rural areas of Nepal are getting electricity from stand-alone solar PV systems. However, there are many challenges including financial, technical, institutional, and governance barriers in Nepal. This study based on extensive review of literatures and author's own long working experiences in renewable energy sector in Nepal, shares the best practices and lessons of off-grid solar PV for increasing access to electricity in rural areas of Nepal. This study suggests that flexible financial instruments, financial innovations, bundling of PV systems for concentrating energy loads, adopting standards process, local capacity building, and combination of technology, financing and institutional aspects are a key for enhancing effectiveness of solar PV technology in rural areas of Nepal.