• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.101.2-101.2
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• 2011

We have developed solar and space weather monitoring system for space weather users since 2007 as a project named 'Construction of Korea Space Weather Prediction Center'. In this presentation we will introduce space weather monitoring system for Geostationary Satellites and Polar Routes. These were developed for satisfying demands of space weather user groups. 'Space Weather Monitoring System for Geostationary Satellites' displays integrated space weather information on geostationary orbit such as magnetopause location, nowcast and forecast of space weather, cosmic ray count rate, number of meteors and x-ray solar flux. This system is developed for space weather customers who are managing satellite systems or using satellite information. In addition, this system provides space weather warning by SMS in which short message is delivered to users' cell phones when space weather parameters reach a critical value. 'Space Weather Monitoring System for Polar Routes' was developed for the commercial airline companies operating polar routes. This provides D-region and polar cap absorption map, aurora and radiation particle distribution, nowcast and forecast of space weather, proton flux, Kp index and so on.

• Journal of Animal Environmental Science
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• v.9 no.2
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• pp.69-78
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• 2003

In this study, the energy conversion equipment from the radiation energy to mechanical energy by using n­pentane as the operating fluid was constructed and the performance to pump the water was tested for the utilization of solar powered water pump. The equipment was designed optimally, after the theoretical analyses of the water pumping head and water quantity per cycle were done. The pentane vapour temperature in the condenser and the temperature of the outlet water from the condenser became lowered and the heat transfer rate became higher with decreasing the water inlet level to the condenser. The temperature difference between the condenser and the water tank was significant. Therefore, the distance between the water tank and condenser was recommended to be shorten and the diameter of their connecting pipe was recommended to be narrow in order to reduce the resistance of the fluid passage and improve the heat transfer rate. The amount of water pumped was 1.6­2.4 liters. Mass flow rate of the cooling water became lowered when the cooling water pipe was prolonged from the condenser to improve the heat transfer rate.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.367-373
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• 2023

Aircrews and passengers are exposed to radiation from cosmic rays and secondary scattered rays generated by reactions with air or aircraft. For aircrews, radiation safety management is based on the exposure dose calculated using a space-weather environment simulation. However, the exposure dose varies depending on solar activity, altitude, flight path, etc., so measuring by route is more suggestive than the calculation. In this study, we developed an instrument to measure the cosmic radiation dose using a general-purpose Si sensor and a multichannel analyzer. The dose calculation applied the algorithm of CRaTER (Cosmic Ray Telescope for the Effects of Radiation), a space radiation measuring device of NASA. Energy and dose calibration was performed with Cs-137 662 keV gamma rays at a standard calibration facility, and good dose rate dependence was confirmed in the experimental range. Using the instrument, the dose was directly measured on the international line between Dubai and Incheon in May 2023, and it was similar to the result calculated by KREAM (Korean Radiation Exposure Assessment Model for Aviation Route Dose) within 12%. It was confirmed that the dose increased as the altitude and latitude increased, consistent with the calculation results by KREAM. Some limitations require more verification experiments. However, we confirmed it has sufficient utilization potential as a cost-effective measuring instrument for monitoring exposure dose inside or on personal aircraft.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.795-802
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• 2012

Geminate electron-hole recombination in organic solids in the presence of a donor-acceptor heterojunction is studied by computer simulations. We analyze how the charge-pair separation probability in such systems is affected by energetic disorder of the media, anisotropy of charge-carrier mobilities, and other factors. We show that in energetically disordered systems the effect of heterojunction on the charge-pair separation probability is stronger than that in idealized systems without disorder. We also show that a mismatch between electron and hole mobilities reduces the separation probability, although in energetically disordered systems this effect is weaker compared to the case of no energetic disorder. We demonstrate that the most important factor that determines the charge-pair separation probability is the ratio of the sum of electron and hole mobilities to the rate constant of recombination reaction. We also consider systems with mobility anisotropy and calculate the electric field dependence of the charge-pair separation probability for all possible orientations of high-mobility axes in the donor and acceptor phases. We theoretically show that it is possible to increase the charge-pair separation probability by controlling the mobility anisotropy in heterojunction systems and in consequence to achieve higher efficiencies of organic photovoltaic devices.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1660-1668
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• 2017

The flow of liquids submerged with nanoparticles is of significance to industrial applications, specifically in nuclear reactors and the cooling of nuclear systems to improve energy efficiency. The application of nanofluids in water-cooled nuclear systems can result in a significant improvement of their economic performance and/or safety margins. Therefore, in this paper, Marangoni thermal convective boundary layer dusty nanoliquid flow across a flat surface in the presence of solar radiation is studied. A two phase dusty liquid model is considered. Unlike classical temperature-dependent heat source effects, an exponential space-dependent heat source aspect is considered. Stretching variables are utilized to transform the prevailing partial differential system into a nonlinear ordinary differential system, which is then solved numerically via the Runge-Kutta-Fehlberg approach coupled with a shooting technique. The roles of physical parameters are focused in momentum and heat transport distributions. Graphical illustrations are also used to consider local and average Nusselt numbers. We examined the results under both linear and quadratic variation of the surface temperature. Our simulations established that the impact of Marangoni flow is useful for an enhancement of the heat transfer rate.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.3
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• pp.75-81
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• 2014

Fossil energy is needed for a whole year greenhouse cropping due to climate in South Korea. Because the most of the fossil energy resources is imported, it is necessary to develop technology to be able to reduce the energy cost in order to manage greenhouse profitably. The greenhouse commonly consume less amount of energy as compared to other industrial sectors. Replacement of fossil fuel with solar thermal storage, therefore, can be an economical as well as environmentally sustainable option for greenhouse heating. The fluid flow, heat storage and radiation characteristic of the gravel bed model were analyzed to provide basic data for design of the experimental solar heated greenhouse with underground thermal storage using gravel. The air flow velocity in the gravel storage bed was proven to be affected from the capacity of circulation fan and the circulation method and the positive pressure method was proven to be the best among the different air circulation methods. The initial air temperature of the thermal storage bed of 1.2 m $wide{\times}9$ m $long{\times}0.9$ m deep was $10^{\circ}C$. After the thermal storage bed is heated by air of the mean temperature $4^{\circ}C$ during 9 hours, the temperature has increased about $20.3^{\circ}C$ and the storage of heat was about 33,000 kcal. The important factors should be taken into consideration for design of the solar heated greenhouse with underground thermal storage using gravel are insulation of rock storage, amount of storing heat, inflow rate and direction of inlet and outlet duct.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.1
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• pp.1-10
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• 1993

A brief description on the greenhouse gases, the greenhoue effect, sea level changes, forcing of climate, the history of Earth's changing climate based on the IPCC REPORT and the records of the recent variation of the climate in the Republic of Kore is presented here for help enhancing awareness of the issues. The climate of the Earth has the potential to be changed on all timescales by the fluctuations of the concentrations of radioactively active greenhouse gases, solar radiation, aerosols and albedo. However, the rate of the recent global warming seems to be larger and rapid than any have occurred thorughout recorded history enough to draw the world-wide attention and worry concerned with the theme of environment and development. There are still uncertainties in the predictions relating to the timing, magnitude and the pattern of the climatic change due to the current incomplete understanding of various aspects of the complex processes. Nonetheless, the scientific results avaliable is sufficient to allow for decisive precautionary measures to be taken.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2005.05a
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• pp.105-109
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• 2005

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.94-97
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• 2005

For the fabrication of poly-crystalline silicon ingot, CCCC (Cold Crucible Continuous Casting) method under a high frequency alternating magnetic field, was utilized in order to prevent crucible consumption and ingot contamination and to increase production rate. In order to effectively and continuously melt and cast silicon, which has a high radiation heat loss due to the high melting temperature and a low induction heating efficiency due to a low electric conductivity, Joule and pinch effects were optimized. Throughout the present investigation, poly-crystalline Si ingot was successfully produced at the casting speed of above 1.5 mm/min under a non-contact condition.

• Atmosphere
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• v.18 no.4
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• pp.429-439
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• 2008

The lower-stratospheric polar temperature in winter and spring for both hemispheres is investigated based on the NCEP/NCAR 50-year reanalysis data with respect to the strength of the stratospheric eddy heat flux. Both the polar temperature and the eddy heat flux show significant variation on the decadal and year-to-year time scales except during the Southern Hemisphere winter. The year-to-year variation in the polar temperature is mainly determined by the eddy heat flux convergence. The eddy heat flux convergence is compared with the diabatic heating rate obtained from a two-dimensional model. Radiative heating caused by absorption of solar radiation is comparable to the heating caused by the eddy heat flux convergence in the Southern Hemisphere. The effect of ozone depletion on diabatic heating has been found to be secondary in the Northern Hemisphere, even in March 1997 when the record depletion of ozone took place.