• Journal of Environmental Science International
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• v.15 no.8
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• pp.701-718
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• 2006

The average ratio of the daily UV-B to total solar (75) irradiance at Busan (35.23$^{\circ}$N, 129.07$^{\circ}$E) in Korea is found as 0.11%. There is also a high exponential relationship between hourly UV-B and total solar irradiance: UV-B=exp (a$\times$(75-b))(R$^2$=0.93). The daily variation of total ozone is compared with the UV-B irradiance at Pohang (36.03$^{\circ}$N, 129.40$^{\circ}$E) in Korea using the Total Ozone Mapping Spectrometer (TOMS) data during the period of May to July in 2005. The total ozone (TO) has been maintained to a decreasing trend since 1979, which leading to a negative correlation with the ground-level UV-B irradiance doting the given period of cloudless day: UV-B=239.23-0.056 TO (R$^2$=0.52). The statistical predictions of daily total ozone are analyzed by using the data of the Brewer spectrophotometer and TOMS in East Asia including the Korean peninsula. The long-term monthly averages of total ozone using the multiplicative seasonal AutoRegressive Integrated Moving Average (ARIMA) model are used to predict the hourly mean UV-B irradiance by interpolating the daily mean total ozone far the predicting period. We also can predict the next day's total ozone by using regression models based on the present day's total ozone by TOMS and the next day's predicted maximum air temperature by the Meteorological Mesoscale Model 5 (MM5). These predicted and observed total ozone amounts are used to input data of the parameterization model (PM) of hourly UV-B irradiance. The PM of UV-B irradiance is based on the main parameters such as cloudiness, solar zenith angle, total ozone, opacity of aerosols, altitude, and surface albedo. The input data for the model requires daily total ozone, hourly amount and type of cloud, visibility and air pressure. To simplify cloud effects in the model, the constant cloud transmittance are used. For example, the correlation coefficient of the PM using these cloud transmissivities is shown high in more than 0.91 for cloudy days in Busan, and the relative mean bias error (RMBE) and the relative root mean square error (RRMSE) are less than 21% and 27%, respectively. In this study, the daily variations of calculated and predicted UV-B irradiance are presented in high correlation coefficients of more than 0.86 at each monitoring site of the Korean peninsula as well as East Asia. The RMBE is within 10% of the mean measured hourly irradiance, and the RRMSE is within 15% for hourly irradiance, respectively. Although errors are present in cloud amounts and total ozone, the results are still acceptable.

• Asia-Pacific Journal of Atmospheric Sciences
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• v.54 no.4
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• pp.599-610
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• 2018

The goal of this study was to statistically analyse the variability of global irradiance and ultraviolet erythemal (UVER) irradiance and their interrelationships with global and UVER irradiance, global clearness indices and ozone. A prediction of short-term UVER solar irradiance values was also obtained. Extreme values of UVER irradiance were included in the data set, as well as a time series of ultraviolet irradiance variability (UIV). The study period was from 2005 to 2014 and approximately 250,000 readings were taken at 5-min intervals. The effect of the clearness indices on global irradiance variability (GIV) and UIV was also recorded and bi-dimensional distributions were used to gather information on the two measured variables. With regard to daily GIV and UIV, it is also shown that for global clearness index ($k_t$) values lower than 0.6 both global and UVER irradiance had greater variability and that UIVon cloud-free days ($k_t$ higher than 0.65) exceeds GIV. To study the dependence between UIVand GIV the ${\chi}^2$ statistical method was used. It can be concluded that there is a 95% probability of a clear dependency between the variabilities. A connection between high $k_t$ (corresponding to cloudless days) and low variabilities was found in the analysis of bidimensional distributions. Extreme values of UVER irradiance were also analyzed and it was possible to calculate the probable future values of UVER irradiance by extrapolating the values of the adjustment curve obtained from the Gumbel distribution.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.293-294
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• 2009

The spectral responsivity of solar cells has been measured under high background irradiance using an LED-based differential spectral responsivity Comparator (DSR-C). The comparator developed is fully automated and has some advantages: It does not need a chopper to modulate the light. Unlike the conventional method, it does not require a monochromator to select wavelength. It covers a wavelength range up to 1200 nm. The wavelength range of the comparator is limited by the spectral power distribution of the LEDs and the spectral responsivity of the standard detector. An active temperature control was utilized to meet the specified standard conditions of solar cell test. This work shows the effect of different levels of background irradiance on the spectral responsivity and the importance of same background irradiance for solar cell test as specified by the corresponding standard.

• Ocean Science Journal
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• v.41 no.4
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• pp.235-244
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• 2006

Determining 'photosynthetically active radiation' (PAR) is a key part of calculating phytoplankton productivity in a biogeochemical model. We explore the daily and seasonal variability in the ratio of PAR irradiance to total irradiance that occurred at Ieodo Ocean Research Station (IORS) in the East China Sea under clear-sky conditions in 2004 using a simple radiative transfer model (RTM). Meteorological data observed at IORS and aerosol optical properties derived from Aerosol Robotic Network observations at Gosan are used for the RTM. Preliminary results suggest that the use of simple PAR irradiance-ratio values is appropriate in calculating phytoplankton productivity as follows: an average of $0.44\;({\pm}0.01)$ in January to an average of $0.48\;({\pm}0.01)$ in July, with average daily variabilities over these periods of about $0.016\;({\pm}0.008)$ and $0.025\;({\pm}0.008)$, respectively. The model experiments demonstrate that variations in the major controlling input parameters (i.e. solar zenith angle, precipitable water vapor and aerosol optical thickness) cause PAR irradiance ratio variation at daily and seasonal timescales. Further, increases (>0.012) in the PAR irradiance ratio just below the sea-surface are positively correlated with high solar zenith angles and strong wind stresses relative to those just above the sea-surface.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.E2
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• pp.74-82
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• 2008

We have examined seasonal and annual means of clear-sky solar noon and daily erythemal ultraviolet-B irradiances measured in Anmyeon. The intensity of the EUV-B irradiance is mainly dependent on solar zenith angle (SZA) and total ozone amounts on clear day conditions. The daily maximum occurs near solar noon time and the highest monthly accumulated EUV-B is seen in July in Anmyeon. The maximum daily variation occurs in June and July due to precipitation and clouds. The 7-year trend of EUV-B irradiance shows that it is slightly increasing. Additionally, we could confirm that aerosol effects such as Asian Dust decreases the EUV-B irradiance reaching the ground surface by 35% to 60%. For more than 45% of the summer days, EUV-B irradiacne was high enough that the UV index registered higher than category Extremely High. This information will be very important for evaluation of the UV index for prevention of both skin cancer and ecosystem damages as well as to understand UV climatology over the Korean Peninsula.

• Animal cells and systems
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• v.7 no.2
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• pp.127-132
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• 2003

Effects of genotype, settlement density and irradiane on the growth, mortality and population structure of Fucus serratus germlings were examined in the laboratory. The growth of F. serratus germlings was influenced by genotype of parent plants, which is likely to occur by microclimatic differentiation of substrata. The growth of germlings were greater at lower densities than higher densities indicating that intraspecific competition between germlings occurred within three weeks. Also, the growth of F. serratus germlings was better at $120\mumol\;m^-2/s^-1$ than at $60\mumol\;m^-2/s^-1$. However, mortality of germlings was determined by settlement density rather than irradiance. In population structure, skewness was increased at low irradiance and high density indicating that population structure could be changed by intraspecific competition. Thus, it is concluded that genotypic differentiation of F. serratus germlings occurred in a microgeographic scale, and the experimental density and irradiance level affected the growth of germlings.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.703-710
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• 2009

The spectral irradiance and underwater transmission characteristics of a combined high-luminance light-emitting diode (LED) lights have been studied to evaluate suitable light sources for fishing lamps of the next generation. The wavelengths at which the irradiance was maximum were changed from 473, 501, 525, and 465 nm for blue, peacock blue, green, and white LED light to 475, 504 and 528 nm for [$F_{WB}$], [$F_{PB}$] and [$F_{GB}$] combined LED lights, respectively. If the irradiance characteristics at 400-700 nm wavelengths are set as 100%, the irradiance rates at 450-499 nm and 500-549 nm were decreased from 82.4% and 56% for blue, peacock blue LED light to 60.0%, 38.5% for [$F_{WB}$], [$F_{WP}$] combined LED lights. The underwater transmission characteristics of the combined LED lights were superior in the order [$F_{WB}$], [$F_{BP}$], [$F_{GB}$] in optical water type I; [$F_{WB}$], [$F_{PB}$], [$F_{GP}$] in optical water type II-III; and [$F_{GP}$], [$F_{WP}$], [$F_{PB}$] in optical water type 1. Setting the 10m depth underwater transmission characteristics of the combined LED lights in optical water type I at 100%, the transmission of water types II, III and 1 drops to 29.5%, 8.0% and 2.2%. Based on the distribution of spectral irradiance and underwater transmission characteristics calculated in optical water types II-III, where was the jigging ground for fishing lamps, the [$F_{WB}]$ and [$F_{GP}$] combined LED lights can be used as a suitable light sources for fishing lamps of the next generation.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.2
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• pp.223-233
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• 2006

We analyzed the monthly and seasonal mean of the daily Erythemal Ultraviolet-B (EUV-B, $280{\sim}320nm$) irradiance operating in Pohang, Anmyeon, Gosan, Mokpo and Kangnung with UV-Biometer (Solar Light Co., Model No. 501) at clear-sky noon during the period from 1999 to 2004. Also, we investigated the seasonal and regional characteristics for the UV index over the Korean Peninsula. The daily maximum occurred near solar southing time and the highest monthly accumulated EUV-B irradiance appeared in July and August at each regional observatory. The monthly mean value of the clear-sky EUV-B irradiance in Pohang, Anmyeon, Gosan, Mokpo and Kangnung showed 196.6, 161.8, 221.9, $171.5mWm^{-2}\;and\;179.7mWm^{-2}$ near noon in July respectively. The annual mean value of the daily accumulated EUV-B irradiance in Pohang, Anmyeon, Gosan, Mokpo and Kangnung were 1.8, 2.1, 2.2, $1.8kJm^{-2}\;and\;1.5kJm^{-2}$ respectively. The UV Index (UVI) showed above UVI 7(High) more than 90 days during one year over the Korean Peninsula.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5310-5316
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• 2013

Maximum Power Point Tracking (MPPT) method for Photovoltaic (PV) system is implemented in PV inveter and it generate the maximum electric power from PV cell. MPPT method has been studied to have high efficiency and high tracking speed. However, these studies are basically focused on the performance under fixed irradiance condition. Based on the typical Perturbation and Observation (P&O) method, this paper presents the research results on modified P&O method to have a better performance under varying irradiance condition. The modified P&O method can have a better performance under varying irradiance condition because the additional measurements during the MPPT control period are conducted. The proposed MPPT method is verified by using 250kW PV inverter under linearly varying irradiance condition according to EN 50530.

• Environmental Engineering Research
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• v.20 no.4
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• pp.347-355
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• 2015

The growth kinetics of phototrophic microorganisms can be controlled by the light irradiance, the concentration of an inorganic nutrient, or both. A multi-component kinetic model is proposed and tested in novel batch experiments that allow the kinetic parameters for each factor to be estimated independently. For the cyanobacterium Synechocystis sp. PCC6803, the estimated parameters are maximum specific growth rate $({\mu}_{max})=2.8/d$, half-maximum-rate light irradiance $(K_L)=11W/m^2$, half-inhibition-rate light irradiance $(K_{L,I})=39W/m^2$, and half-maximum-rate concentration for inorganic carbon $(K_{S,Ci})=0.5mgC/L$, half-maximum-rate concentration for inorganic nitrogen $(K_{S,Ni})=1.4mgN/L$, and half-maximum-rate concentration for inorganic phosphorus $(K_{S,Pi})=0.06mgP/L$. Compared to other phototrophs having ${\mu}max$ estimates, PCC6803 is a fast-growing r-strategist relying on reaction rate. Its half-maximum-rate and half-inhibition rate values identify the ranges of light irradiance and nutrient concentrations that PCC6803 needs to achieve a high specific growth rate to be a sustainable bioenergy source. To gain the advantages of its high maximum specific growth rate, PCC6803 needs to have moderate light illumination ($7-62W/m^2$ for ${\mu}_{syn}{\geq}1/d$) and relatively high nutrient concentrations: $N_i{\geq}2.3 mgN/L$, $P_i{\geq}0.1mgP/L$, and $C_i{\geq}1.0mgC/L$.