• KIEAE Journal
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• 제14권5호
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• pp.67-73
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• 2014

This study aims at examining kinetic efficient shading systems and their implementation methods. These days, the importance of the shading devices are getting more significant due to the energy problem. Cordially, suitable shade designs are required as an important element for the exterior envelope of the building. This study employs the optimal shading design as an efficient shading method with the kinetic system that can be converted actively by the altitude of the sun. The proposed kinetic shading system works not only as a lightshelf in case the altitude of the sun is high but also as a vertical louver when the sun is getting lower in order to block the direct sunlight. This study has analyzed the thermal performance and shading coefficient of the kinetic shading system in comparison to existing fixed shading devices using the Ecotect. The results, in sum, conclude that the suggested kinetic shading system could decrease direct sunlights 26.2% more than the existing shading methods.

• 한국환경복원기술학회지
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• 제11권6호
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• pp.112-119
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• 2008

본 연구는 자주중산국수나무와 자주맥문동의 광도변화에 따른 생육 및 생리 특성과 엽색발현을 조사하여 적정 광도를 구명하고자 한 결과는 다음과 같다. 1.자주색 잎이 특징인 중산국수나무(Physocarpus opulifolius 'Diabolo')는 차광에 따른 생육 변화를 관찰한 결과 40% 차광구에서 생육이 좋았으나 양지조건일 때 생리활성이 2배 이상 좋은 것으로 나타났다. 엽색발현은 0% 차광구에서 85% 차광구로 갈수록 진한 자주색(RHS colour chart 202A, dark grayish red)에서 녹색(RHS colour chart 139A, dark yellowish green)으로 변화되어 본래의 품종 특성인 엽의 색이 사라져 관상가치면에서 저하된 것으로 사료되어진다. 2.자주맥문동(Ophiopogon planiscapus 'Nigrescens')은 노지상태인 무차광구에서 생육이 가장 양호하였고, 관상가치면에서 생육활성이 좋은 대조구에서 선명한 자주색이 잘 나타났으며 더욱 진해진 검붉은색(RHS colour chart 202A, dark grayish)으로 엽색이 발현되었다.

• KIEAE Journal
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• 제14권2호
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• pp.21-28
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• 2014

This paper provides the up to date review of the shading effects on PV module performance and the associated detection algorithm related to the maximum power point tracking. It includes the brief explanations of the MMP variations due to the shading occurrence on the PV modules. Review of experimental and simulation studies highlighting the significant impacts of shading on PV efficiencies were presented. The literature indicates that even the partial shading of a single cell can greatly drop the entire module voltage and power efficiency. The MMP tracking approaches were also reviewed in this study. Both conventional and advanced soft computing methods such as ANN, FLC and EA were described for the proper tracking of MMP under shaded conditions. This paper would be the basic source and the comprehensive information associated with the shading effects and relevant MPP tracking technique.

• 한국태양에너지학회 논문집
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• 제35권2호
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• pp.93-101
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• 2015

Zero energy building is a self sufficient building that minimizes energy consumption through passive elements such as insulation, high performance window system and installing of high efficiency HVAC system and uses renewable energy sources. The Korea Government has been strengthening the building energy efficiency standard and code for zero energy building. The building energy performance is determined by the performance of building envelope. Therefore it is important to optimize facade design such as insulation, window properties and shading, that affect the heating and cooling loads. In particular, shading devices are necessary to reduce the cooling load in summer season. Meanwhile, BIPV shading system functions as a renewable energy technology applied in solar control facade system to reduce cooling load and produce electricity simultaneously. Therefore, when installing the BIPV shading system, the length of shadings and angle that affect the electricity production must be considered. This study focused on the facade design applied with BIPV shading system for maximizing energy saving of the selected standard building. The impact of changing insulation on roof and walls, window properties and length of BIPV shading device on energy performance of the building were investigated. In conclusion, energy consumption and electricity production were analyzed based on building energy simulations using energyplus 8.1 building simulation program and jEPlus+EA optimization tool.

• Journal of Power Electronics
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• 제18권5호
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• pp.1489-1500
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• 2018

Partial shading analysis of large-scale photovoltaic (PV) arrays has recently become a theoretically and numerically challenging issue, and it is necessary for PV system designers. The main contributions of this study are the following: 1) A PSIM-based macro-model was employed because it is remarkably fast, has high precision, and has no convergence issues. 2) Three types of equivalent macro-models were developed for the transformation of a small PV sub-array with uniform irradiance to a new macro-model. 3) On the basis of the proposed new macro-model, a tearing method was established, which can divide a large-scale PV array into several small sub-arrays to significantly improve the efficiency improvement of a simulation. 4) Three platforms, namely, PSIM, PSpice, and MATLAB, were applied to evaluate the proposed tearing method. The proposed models and methods were validated, and the value of this research was highlighted using an actual large-scale PV array with 2420 PV modules. Numerical simulation demonstrated that the tearing method can remarkably improve the simulation efficiency by approximately thousands of times, and the method obtained a precision of nearly 6.5%. It can provide a useful tool to design the optimal configuration of a PV array with a given shading pattern as much as possible.

• 한국약용작물학회지
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• 제20권5호
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• pp.320-330
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• 2012

This study was conducted to investigate the changes of chlorophyll contents, chlorophyll fluorescence, photosynthetic parameters, and leaf growth of Synurus deltoides under different shading treatments. S. deltoides was grown under non-treated (full sunlight) and three different shading conditions (Shaded 88~93%, 65~75%, and 45%~55%). Light compensation point ($L_{comp}$), dark respiration ($D_{resp}$), maximum photosynthesis rate ($Pn_{max}$), photo respiration rate ($P_{resp}$), carboxylation efficiency ($\Phi_{carb}$), and photochemical efficiency were decreased with increasing shading level; However, $CO_2$ compensation point ($CO_{2\;comp}$), total chlorophyll content, and specific leaf area (SLA) were shown the opposite trend. S. deltoides under 88~93% treatment showed the lowest photosynthetic activity such as maximum photosynthetic rate ($Pn_{max}$), photochemical efficiency, and $CO_2$ compensation point ($CO_{2\;comp}$). Therefore, photosynthetic activity will be sharply decreased with a long period of 8~12% of full sunlight. With the shading level decreased, carotenoid content and non-photochemical fluorescence quenching (NPQ) increased to prevent excessive light damage. This result suggested that growth and physiology of S. deltoides adapted to high light intensity through regulating its internal mechanism.

• 현장농수산연구지
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• 제25권4호
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• pp.84-89
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• 2024

과수에서 생산량과 품질을 결정하는 조건 중 가장 중요한 것은 광이다. 차광은 광합성 효율을 떨어뜨리는 직접적인 원인으로 매실과 같이 생육기간이 짧은 과수에서 피해는 더 크게 나타난다. 본 연구에서는 최근 과수 주산단지에 일조방해에 의한 피해가 증가함에 따라 매실에서 차광조건이 생산량과 품질에 미치는 영향을 조사하였다. 차광시간이 증가함에 따라 매실의 평균 광합성 유효광선 (PAR) 조사량은 무처리 (304μmol/m²/s)에 비해 급격히 감소하여 8시간 차광에서는 142μmol/m²/s로 나타났다. 하루 중 광합성 효율이 최대(PAR 900~1,000μmol/m²/s)인 시간은 무처리와 차광 2시간은 5시간(오전 11시~오후 3시), 차광 4시간은 2시간(오후 1시~2시)이었으며, 6시간, 8시간 차광은 하루 종일 낮은 광량이 조사되었다. 차광시간에 따른 매실의 과중은 차광 2시간까지는 차이가 없었으나, 차광시간이 길어짐에 따라 유의하게 감소되었다. 산함량과 과형지수는 차광시간에 따라 유의한 차이가 없었으나 과실의 당도는 시간이 증가함에 따라 감소하였다. 결론적으로 매실의 2시간 이상의 차광은 과중과 당도를 떨어뜨리며 단위 면적당 생산량과 상품성 가치 하락에 직접적인 영향을 미친다.

• KIEAE Journal
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• 제17권2호
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• pp.29-34
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• 2017

Purpose: Recently, significant heat loss through the window takes place in buildings. Nevertheless, there exists little literature concerning the exterior horizontal shading devices and the design criteria are not clearly settled yet. Applying the exterior horizontal shading devices is more efficient as compared to the interior shading devices in that solar radiation can be directly blocked before passing through the window or the envelope. The purpose of this study is to reduce the internal load by designing the exterior horizontal shading devices and verify the degree of reduction in energy consumption. Method: This study aims to reduce energy consumption in cooling and heating through proposing proper length and shape of the exterior horizontal shading devices in public buildings. In the process, actual energy data and the Design Builder simulation program are utilized. In addition, economic aspect is considered to figure out the optimal length of the exterior horizontal shading devices that maximizes efficiency. Result: As a result, the proper length and shape of the exterior horizontal shading devices are provided as follows: 1) Energy consumption in cooling and heating is minimized when the exterior horizontal shading devices are designed as 0.5m*2. 2) Electricity bill is the lowest when the exterior horizontal shading devices are designed as 3.3m*2. The gap between maximum and minimum electricity bill is about 7.8~14%.

• 원예과학기술지
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• 제32권5호
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• pp.584-589
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• 2014

Jeffersonia dubia is a spring-flowering perennial found in rich forests in Korea and Northern China and has potential as an ornamental or medicinal plant. However, illegal picking and land use change have decreased the number of populations and overall population size of this plant in its natural habitat. Although J. dubia has been reported to be a shade-preferring plant, no study has determined the optimum light intensity for its growth. The objectives of this work were to observe the effects of various shading levels on the physiological responses of J. dubia and to determine the proper shading level for cultivation. Treatments consisted of four shading levels (0%, 50%, 75%, and 95% shade) imposed using black mesh cloth. The number of leaves and dry weight increased with decreased shading. The shoot-to-root ratio increased with increased shading, mainly due to decreased root dry weight under shading. Plants showed low net $CO_2$ assimilation rates and $F_v/F_m$ values combined with low dry matter levels when grown under 0% shade (full sunlight). These results indicate that J. dubia plants experience excessive irradiance without shading, resulting in damage to the photosynthetic apparatus. By contrast, the net photosynthesis rate increased as the shading level increased. $F_v/F_m$, the potential efficiency of PSII, was 0.8 under 95% shade, indicating that J. dubia is well-adapted under heavy shading. However, the low dry matter of plants in the 95% shade treatment indicated that the low light intensity under 95% shade led to a decline in plant growth. Thus, moderate light (50% shading) is recommended for cultivating J. dubia without physiological defects.

• 전력전자학회논문지
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• 제25권4호
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• pp.311-318
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• 2020

A photovoltaic (PV) system uses an AC module integrated converter (MIC) to operate PV cells at a maximum power point (MPP) and for high efficiency. The MPP of a PV cell varies depending on partial shading conditions, and loss occurs differently according to the configuration method of the PV-MIC. Therefore, this study compares the losses of passive components and power semiconductors according to the partial shading conditions of the PV module. Theoretical loss analysis is performed using parameters for the datasheet and PSIM simulation results. Analysis results verify that the one-stage PV-MIC demonstrates high efficiency.