• Title/Summary/Keyword: Solar Position

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Development and Performance Evaluation of a Sloped Lightshelf Daylighting System (Mock-up model을 이용한 경사형광선반 채광시스템의 개발 및 채광성능평가에 관한 연구)

  • Kim, Jeong-Tai;Kim, Ki-Cheol;Kim, Gon
    • Journal of the Korean Solar Energy Society
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    • v.24 no.2
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    • pp.39-50
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    • 2004
  • One of the challenge for successful daylighting design might be to capture sunlighting that varies in both intensity and position and to deliver the luminous flux into the inner space as deep as possible. Conventional glazing apertures allow daylight in the outer 3.5m of a perimeter spaces. More advanced daylighting technologies can extend this daylighting depth by reflecting sunlight further from the windows within a deep floor area. For this purpose, this study developed light shelves based on performance evaluation with a mock-up model that constructed recently and measured under real sky condition. All these daylighting devices have a customized geometry developed from the solar path at a given latitude and utilize unique reflecting finishing to maximize the amount of redirection and diffusion of the daylight. This paper tells that the best daylighting penetration typically can be expected from using light-colored sloped external shelves.

Study on IR Signature Characteristics for different Transmittance over the Korean South Sea during Summer and Winter Seasons (거제도 해양의 여름 및 겨울철 환경에서 거리에 따른 대기투과도를 고려한 함정의 적외선 신호 특성 분석)

  • Choi, Jun-Hyuk;Kim, Jung-Ho;Jung, In-Hwa;Lee, Phil-Ho;Kim, Tae-Kuk
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.2
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    • pp.320-327
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    • 2010
  • The IR signature data of a ship is mainly affected by location, meteorological conditions(atmosphere temperature, wind direction and velocity, humidity etc.), atmospheric transmittance, solar position and ship surface temperature etc. The IR signatures received by a remote sensor at a given temperature and wavelength region is consisted of the self-emitted component directly from the object surface, the reflected component of the solar irradiation at the object surface, and the scattered component by the atmosphere without ever reaching the object surface. Computer simulations for prediction of the IR signatures of ships are very useful to examine the effects of various sensor positions. In this paper, we have acquired the IR signature for different sensor positions by using computer program for prediction of the IR signatures. The numerical results show that the IR signature contrast as compared to the background sea considering the meteorological conditions, solar and sky irradiations.

High altitude powered lighter-than-air vehicle as remote sensing platform

  • Onda, Masahiko
    • 제어로봇시스템학회:학술대회논문집
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    • 1990.10b
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    • pp.1361-1364
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    • 1990
  • In order to tackle global environmental problems such as destruction of the ozone layer or climatic changes due to atmospheric temperature increase, the acquisition of plentiful and precise data is necessary. Therefore, a means of conducting long-lasting high-resolution measurements over broad areas is required. A feasibility study has been made on a high altitude (20km), super-pressured helium-filled PLTA (Powered Ligher-than-Air) vehicle as an ideal platform for environmental observation. It has a long service life and carries a larger payload than an artificial satellite. This PLTA platform uses an electric propulsion system to maintain position in space against wind currents. The thruster is driven by solar power acquired from solar cells. For night use, solar energy is stored in regenerative fuel cells. This study focuses on energy balance and structural analysis of the hull and platform. The platform is capable of conducting high resolution remote sensing as well as having the capability to serve as a telecommunications relay. The platform could replace a number of ground-based telecommunications relay facilities, guaranteeing sufficient radio frequency intensity to secure good quality telecommunication transmittal. The altitude at which the platform resides has the lowest wind flow in the lower stratosphere, and permits viewing from the ground within a 1,000km range. Because this altitude is much lower than that required of an artificial satellite, the measuring resolution is a couple of thousand times higher than with artificial satellites. The platform can also be used to chase typhoons and observe them from their sources in tropical regions.

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A Study on Optimum of Performance Objectives of Passive House with Load Reduction elements (천공상태에 따른 박막 BIPV 창호의 온도 및 발전특성 실측연구)

  • Kim, Bit-Na;Yoon, Jong-Ho;Shin, U-Cheu
    • 한국태양에너지학회:학술대회논문집
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    • 2012.03a
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    • pp.171-176
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    • 2012
  • This research on building Integrated Photovoltaic System replacing windows and doors with amorphous silicon thin film PV windows and doors installing same exact mount on Mock-up. The windows and doors should be installed in different angle and bearing so that we can analyse the amount of electricity from them. The objective of the research is to evaluate and investigate the relationship between factors(intensity of solar radiation, PV window surface temporature, incidence angle, and sky conditions) that affects performance of PV window and performance. The range and method of this research is to establish mornitoring system and analysis the date from the mornitoring system to evaluate the performance of PV windows that has thin film of solar battery. We should evaluate the insolation according to the position of PV window, output, and surface temperature according to months and seasons so that we can figure out the relationship between these. And we should investigate the relationship between performance and efficiency according to incidence angle and sky condition so that we can figure out the correlation between factors and performance.

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Development of Automatic Tracking Control Algorithm for Efficiency Improvement of PV Generation (태양광 발전의 효율 향상을 위한 자동추적 제어 알고리즘 개발)

  • Choi, Jung-Sik;Ko, Jae-Sub;Chung, Dong-Hwa
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.10
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    • pp.1823-1831
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    • 2010
  • This paper proposes an automatic tracking control algorithm for efficiency improvement of photovoltaic generation. Increasing the power of PV systems should improve the efficiency of solar cells or the power condition system. The normal alignment of the PV module always have to run perpendicular to the sun's rays. The solar tracking system, able to improve the efficiency of the PV system, was initiated by applying that to the PV power plant. The tracking system of conventional PV power plant has been studied with regard to the tracking accuracy of the solar cells. Power generation efficiency were increased by aligning the cells for maximum exposure to the sun's rays. Using a perpendicular position facilitated optimum condition. However, there is a problem about the reliability of tracking systems unable to not track the sun correctly during environmental variations. Therefore, a novel control algorithm needs to improve the generation efficiency of the PV systems and reduce the loss of generation. This control algorithm is the proposed automatic tracking algorithm in this paper. Automatic tracking control is combined the sensor and program method for robust control in environment changing condition. This tracking system includes the insolation, rain sensor and anemometer for climate environment changing. Proposed algorithm in this paper, is compared to performance of conventional tracking control algorithm in variative insolation condition. And prove the validity of proposed algorithm through the experimental data.

High-Efficiency Dye-Sensitized Solar Cells by Extended Spectral Response Utilizing Dye Selective Positioning Method

  • Lee, Do-Gwon;Park, Se-Ung
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2010.05a
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    • pp.12.1-12.1
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    • 2010
  • We have developed a facile method to position different dyes (N719 and N749) sequentially in a mesoporous TiO2 layer through selective desorption and adsorption processes. Only upper part of the first adsorbed N719 dye was selectively removed by the desorption solution formulated with polypropylene glycol and tetrabutylammonium hydroxide without any damages of the dye. The desorption depth was controlled by the number of desorption process. Multi-dyed dye-sensitized solar cells (MDSSC) were fabricated by utilizing the method and their photovoltaic properties were investigated. From the incident photon-to-current conversion efficiency (IPCE) measurement, it was found that the MDSSC exhibited the extended spectral response for the solar spectrum while without decrease of maximum IPCE value compare to the DSSCs using one kind of dye (N719 or N749). The highest photocurrent density of 19.3 mA/cm2 was obtained from the MDSSC utilizing $15\;{\mu}m$ N719 / $14\;{\mu}m$ N749 bi-layered mesoporous TiO2 film. The photocurrent density was 25% and 8% higher than that of the DSSC using only N719 and N749 dye as a sensitizer, respectively. The power conversion efficiency of 9.8% was achieved from the MDSSC under the AM 1.5G one sun illumination.

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Nanocrystalline Antimony Oxide Films for Dye-Sensitized Solar Cell Applications

  • Kim, Ji-Hye;Jang, Ji-Yeon;Kim, Sung-Chul;Han, Chi-Hwan;Kim, Seung-Joo
    • Bulletin of the Korean Chemical Society
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    • v.33 no.4
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    • pp.1204-1208
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    • 2012
  • A new photoelectrode composed of $Sb_6O_{13}$ nanoparticles with the size of 20-30 nm has been prepared via thermolysis of a colloidal antimony pentoxide tetrahydrate ($Sb_2O_5{\cdot}4H_2O$) suspension. The $Sb_6O_{13}$ electrode showed good semiconducting properties applicable to dye-sensitized solar cells (DSSCs); the energy band gap was estimated to be $3.05{\pm}0.5$ eV and the position of conduction band edge was close to those of $TiO_2$ and ZnO. The DSSC assembled with the $Sb_6O_{13}$ photoelectrode and a conventional ruthenium-dye (N719) exhibited the overall photo-current conversion efficiency of 0.74% ($V_{oc}$ = 0.76 V, $J_{sc}=1.99\;mAcm{-2}$, fill factor = 0.49) under AM 1.5, $100\;mWcm^{-2}$ illumination.

Development of Tracking Algorithm to Improve Accuracy of Altitude and Azimuth (태양 고도각 및 방위각 제어의 정확도 향상을 위한 추적 알고리즘 개발)

  • Back, Jung-Woo;Ko, Jae-Sub;Choi, Jung-Sik;Jang, Mi-Geum;Kang, Sung-Jun;Chung, Dong-Hwa
    • Proceedings of the KIEE Conference
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    • 2009.04b
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    • pp.219-221
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    • 2009
  • This paper analyzes efficiency of photovoltaic(PV) tracking system using solar location algorithm(SLA). Solar location tracking system is needed for efficiently and intensively using PV system independent of environmental condition. PV tracking system of program method is presented a high tracking accuracy without the wrong operating in rapidly changed insolation by the clouds and atmospheric condition. Therefore, this paper analyzes efficiency of PV system using SLA for more correct position tracking of solar. Also, controlled altitude angle and azimuth angle by applied algorithm is compared with data of korea astronomy observatory. And this paper analyzes the tracking error and proves the validity of applied algorithm.

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Planning the Blind Position Considering Thermal Performance in the Intermediate Space of Double-Skin Facade (이중외피 중공층의 열성능을 고려한 블라인드 위치 계획)

  • Choi Dong-Hee;Jo Jae-Hun;Seok Ho-Tae;Yeo Myoung-Souk;Kim Kwang-Woo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.7
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    • pp.620-628
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    • 2005
  • The blinds in the intermediate space are installed to block the direct solar radiation. As the blind divide the airflow of intermediate space into two, thermal performance of Double-Skin Facade (DSF) are affected by the blind position. Therefore blind position should be planed with careful consideration in order to maximize the thermal performance of DSF. In this study, CFD was peformed to analyze the effect of blind position in multistory-type DSF in variation of other DSF elements. The simulation results showed that the case with narrow depth of intermediate space and outlet on upper side of outer-facade, it is profitable to place blind as close as possible to the outer-facade. In the other cases, the blind should maintain 0.15 m distance from outer-facade.

Planning of the Blind Position Considering Thermal Performance in the Intermediate Space of Double-Skin Facade

  • Choi Dong-Hee;Jo Jae-Hun;Seok Ho-Tae;Yeo Myoung-Souk;Kim Kwang-Woo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.14 no.2
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    • pp.57-65
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    • 2006
  • The blinds in the intermediate space are installed to block the direct solar radiation. As the blind divides the airflow of intermediate space into two parts, thermal performance of Double-Skin Facade(DSF) is affected by the blind position. Therefore the blind position should be planned with careful consideration in order to maximize the thermal performance of DSF. In this study, CFD was performed to analyze the effect of blind position in multistory-type DSF in variation of other DSF elements. The simulation results showed that the case with narrow depth of intermediate space and outlet on upper side of outer-facade, it is profitable to place blind as close as possible to the outer facade. In the other cases, the blind should maintain 0.15m distance from outer facade.