• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2013년도 추계 학술발표논문집
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• pp.67-72
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• 2013

• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2014년도 추계 학술발표논문집
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• pp.217-221
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• 2014

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.23.4-23.4
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• 2008

In March and April 2001, the apogee (~9 Re) of the Polar spacecraft was located near the subsolar magnetopause with its orbital plane nearly parallel to a magnetic meridian plane. Polar electric and magnetic field data acquired during the two-month interval of solar maximum have been used to study fundamental standing Alfven waves near the subsolar meridian plane (magnetic local time = 1000-1400 hours) at magnetic latitudes from the equator to $\pm45$ degrees and at L values between 7 and 12. In the frequency band from 1.5 to 10 mHz, fundamental mode oscillations were identified based on high coherence (more than 0.7) and an approximately 90-degree phase shift between the azimuthal magnetic and radial electric field components. The L dependence of the fundamental frequencies is studied, and the frequencies are compared with those observed near the solar minimum interval (Takahashi et al. 2001). We found that the average frequencies in solar maximum are lower than those in solar minimum by a factor of ~2. This implies that the mass density in solar maximum is higher than that in solar minimum by a factor of ~4. Since there is a positive correlation between solar irradiance and solar activity, we suggest that the ionosphere in solar maximum produces more ions and load magnetic flux tubes with more ions.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.60-67
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• 2011

A photovoltaic/thermal(PVT)solar system is the solar technology that allows for simultaneous conversion of solar energy into both electricity and heat. This paper compared the performance of PVT system with a conventional PV module and solar collector and analyzed electrical and thermal efficiency of PVT system in terms of solar irradiance and inlet temperature of the working fluid. Based on the experimental data, thermal and electrical efficiencies of the glazed PVT system were 57.9% and 14.27% under zero reduced temperature condition which were lower by 13.6% than the solar thermal absorber plate and by 0.08% than the PV module respectively. For the unglazed PVT system, it had lower thermal efficiency than the solar thermal absorber plate but higher electrical performance than the PV module due to the cooling effect by the working fluid. However, total efficiency of the glazed PVT system was 72.2% which was higher than combined efficiencies of the solar collector and PV module. Besides, total efficiency of the PVT system would be much higher if calculated based on unit area.

• 천문학회보
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• 제41권1호
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• pp.45.3-46
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• 2016

Solar activity shows a self-similarity as it has many periods of activity cycle in the time series of long-term observation, such as 13.5, 51, 150, 300 days, and 11, 88 years and so on. Since fractal dimension is a quantitative parameter for this kind of an irregular time series, we applied this method to long-term observations including sunspot number, total solar irradiance, and 3.75 GHz solar radio flux to predict the start and maximum times as well as expected maximum sunspot number for the next solar cycle. As a result, we found that the radio flux data tend to have lower fractal dimensions than the sunspot number data, which means that the radio emission from the sun is more regular than the solar activity expressed by sunspot number. Based on the relation between radio flux of 3.75 GHz and sunspot number, we could calculate the expected maximum sunspot number of solar cycle 24 as 156, while the observed value is 146. For the maximum time, estimated mean values from 7 different observations are January 2013 and this is quite different to observed value of February 2014. We speculate this is from extraordinary extended properties of solar cycle 24. As the cycle length of solar cycle 24, 10.1 to 12.8 years are expected, and the mean value is 11.0. This implies that the next solar cycle will be started at December 2019.

• 한국환경과학회지
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• 제23권11호
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• pp.1943-1951
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• 2014

In order to clarify the characteristics of Photo-Volatic(PV) power generation over the Korean peninsula with complex terrain, special meteorological observation campaign was carried out for one year from 25 May 2011. Analysis is based on the comparison between observed meteorological elements and PV values generated at rated capacity 200 kW power plants. Solar radiation observed at $15^{\circ}$ inclined surface is 11 % larger than that observed at horizontal surface due to low elevation angel of the sun during winter season. The PV power generation tend to be more similar the variation of inclined surface irradiance than horizontal surface irradiance. Increasing air temperature often induce disturbance of the PV power generation. However, the higher the air temperature in winter season, the higher PV power generation because the PV module may be more activated at higher air temperature. PV generating efficiency tends to be conversed the value of 15%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.71-72
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• 2008

This paper describes a circuit based simulation model for a Photovoltaic(PV) cell in order to estimate the electrical behavior of the solar cell module with changes of environmental parameters such as shunt resistance, series resistance, temperature and irradiance. An accurate I-V model of PV module is presented based on the Shockley diode model. The general model was implemented on Matlab scrip file, and used irradiance and temperature as variables and outputs of the I-V characteristic. A typical PV module was used for the evaluation, and results was compared with reference taken directly from the manufacturer's published curves leading to excellent agrement with the theoretical prediction.

• 통합자연과학논문집
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• 제10권1호
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• pp.58-63
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• 2017

Photovoltaic (PV) are generally modeled using mathematical equations that describe the PV system behavior. Most of the modeling approach is very simple in terms of that PV module temperature is calculated from nominal constant cell temperature such as ambient temperature and incoming solar irradiance. In this paper, we newly present MATLAB model particularly embedding the effect of wind speed to describe more accurate cell temperature. For analyses and validate purpose of the proposed model, solar power is obtained and compared with and without wind speed from the 50Wp PV module provided by vendor datasheet. In the simulation result, we found that power output of the module is increased to 0.37% in terms of cell temperature a degreed down when we consider the wind speed in the model. This result is well corresponded with the well-known fact that normal PV is 0.4% power changed by cell temperature a degree difference. Therefore it shows that our modeling method with wind speed is more appropriate than the methods without the wind speed effect.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.965-969
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• 2006

This study investigated heat transfer characteristics between absorber and heat pipe used to extract heat from concentric evacuated tubular collectors. In order to experiment, T-type thermocouples are attached to a evaporator of heat pipe and absorber of inner tube. A wall temperature distribution of absorber and heat pipe were carried out by experimental method under actual various ir-radiance and outdoor conditions. As a result, As to increase an irradiance, a wall temperature of absorber and heat pipe is gradually increased. The heat pipe was required about 20min to obtain steady state operation after start up and operates stable during various irradiance conditions. And the collector efficiency was about $50{\sim}70%$ when a mass flow rate is about $1.3{\ell}/min$.

• 한국태양에너지학회 논문집
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• 제34권1호
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• pp.19-27
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• 2014

Exterior vertical illuminance is an important factor for lighting control. But, there are not many researches about the exterior illuminance on a vertical surface. In this study, we predicted the exterior illuminance on a vertical surface using vertical luminous efficacy. First, we calculated the vertical luminous efficacy according to the sky clearness category. And we performed the statistical analysis of the measured and the calculated illuminance with luminous efficacy. The MBE and RMSE of the predicted exterior illuminance were-1.2% and 15.5%, respectively. Second, the annual illuminance on a vertical surface calculated with the luminous efficacy and the short-term measured solar irradiance was suggested in this study.