• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.372-376
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• 2014

This study is on acoustic radiation efficiency of a tiffened cylindrical model in water-multi-excitation with phase difference using commercial numerical program ABAQUS and SYSNOISE. When the stiffened cylindrical model is under multi-excitation with phase difference, the surface vibration field is variated with phase difference of excitation. By this different surface vibration field, the acoustic radiation efficiency is also variated with phase difference of excitation.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.110-114
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• 2009

The model to calculate the solar radiation at the surface was developed and the annual global solar radiation calculated by the model was compared with the KMA(Korea Meteorological Administration) surface measured data The difference between calculated and measured values was distinguished clearly because of the calibration problem of the pyranometer, but the global distribution of solar radiation calculated by the model was very similar to NREL(National Renewable Energy Laboratory) result of USA.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.194-198
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• 2006

In this study, numerical modeling was performed to analyze air flow including radiation heat transfer inside a small chamber. Characteristics of heat transfer between source plate and target through glass are investigated for various surface temperature of heat source plate with buoyancy effect due to gravity force. Conduction heat transfer through the glass is considered and heat source plate is assumed to be a black body. Target surface temperature is largely affected by the radiation heat transfer. It can also be seen that as the source temperature increases target surface is dominated by radiation rather than convective heat transfer by air.

• Journal of the Korea Convergence Society
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• v.8 no.2
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• pp.113-120
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• 2017

The purpose of this present study was to evaluate the surface radiation dose reduction and radiograph artifact images in computed tomography (CT) for the manufactured radiation shields by using sea-shells. The radiation convergence shields were made from silicons, sea-shells, barium powders, producted circle types of diameter 50 mm, thickness 3.5 mm for 5 kinds (only silicon shield, only barium shield, mixed sea-shells with silicon shield, mixed barium with silicon shield, mixed sea-shells with barium and silicon shield). Radiation generation and acquisition were used 4-channel multi-detector CT. The results of this study showed that mixed sea-shells with silicon shields could reduce the surface dose of 5.3% without radiograph artifact images. In the future, we will expect the radiation convergence shield as environmentally friendly materials by using the recycling of sea-shells with the advantages of silicon which can make various shapes.

• KIEAE Journal
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• v.14 no.4
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• pp.35-45
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• 2014

The main objective of this study is to provide an effective algorithm of the transmitted solar radiation calculation through window glazing on a clear day. This algorithm would be used in developing a computer program for fenestration system analysis and shading device design. Various simulation methods have been evaluated to figure out the most accurate and effective procedure in estimation of transmitted solar radiation on a tilted surface on a clear day. Characteristics of simulated results of each step have been scrutinized by comparing them with measured results of the site as well as results from other simulation programs. Generally, the Duffie & Beckman's solar calculation method introducing the HDKR anisotropic model provided the most reliable simulation results. The DOE-2 program usually provided over-estimated simulation results. The estimation of extraterrestrial solar radiation and beam normal radiation were conducted pretty accurately. However, the solar radiation either on horizontal surface or on tilted surface involves complicated factors in estimation. Even though the estimation results were close to the real measured data during summer when solar intensity is getting higher, the estimation provided more error when solar intensities were getting weaker. The convex polygon clipping algorithm with homogeneous coordinates was fastest model in calculation of sunlight to shaded area ratio. It could not be applied because of its shape limitation.

• KIEAE Journal
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• v.14 no.3
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• pp.65-70
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• 2014

The thermal environment in a small city rapidly deteriorates due to the urbanization and overpopulation. It is important to understand and predict the thermal environment in a city area. The thermal environment is highly affected by the solar radiation and temperature distributions changing over time periodically. To predict the thermal environment precisely, the solar radiation calculation including radiation strength, incidence angle, and thermal radiation between building surface and ground should be considered. In this study, the computational domain includes various artificial structures such as building, ground, asphalt, brick and grass. To consider the solar radiation, the unsteady state numerical calculation is performed from sun rise to mid-day (2:00pm). The numerical methods consist of solar load and one dimensional heat conduction through the boundaries to reduce the computational load and improve the flexibility of the calculation.

• Journal of the Korean Solar Energy Society
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• v.31 no.2
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• pp.99-106
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• 2011

Since the solar energy resource is the main input for sizing any solar photovoltaic system, it is essential to utilize the solar radiation data as an application and development of solar energy system increase. It will be necessary to understand and evaluate the insolation data. The Korea Institute of Energy Research(KIER) has begun collecting horizontal global insolation data since May, 1982 at 16 different locations in Korea and for the more detailed analysis, images taken by geostationary satellite may be used to estimate solar irradiance fluxes at earth"s surface. It is based on the empirical correlation between a satellite derived cloud index and the irradiance at the ground. From the results, the measured data has been collected at 16 different stations and estimated using satellite at 23 different stations over the South Korea from 1982 to 2009. The Result of analysis shows that the annual-average daily global radiation on the horizontal surface is 3.56 kWh/ $m^2$/day and estimated solar radiation fluxes show reliable results for estimating the global radiation with average deviation of -7.27 to +3.65% from the measured values.

• Journal of Radiation Protection and Research
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• v.43 no.4
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• pp.131-136
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• 2018

Background: We investigated the current characteristics of a thin-film Ag electrode on a chemical vapor deposition (CVD) diamond. The CVD diamond is widely recognized as a radiation detection material because of its high tolerance against high radiation, stable response to various dose rates, and good sensitivity. Additionally, thin-film Ag has been widely used as an electrode with high electrical conductivity. Materials and Methods: Considering these properties, the thin-film Ag electrode was deposited onto CVD diamonds with varied deposition thicknesses (${\fallingdotseq}50/98/152/257nm$); subsequently, the surface thickness, surface roughness, leakage current, and photo-current were characterized. Results and Discussion: The leakage current was found to be very low, and the photo-current output signal was observed as stable for a deposited film thickness of 98 nm; at this thickness, a uniform and constant surface roughness of the deposited thin-film Ag electrode were obtained. Conclusion: We found that a CVD diamond radiation detector with a thin-film Ag electrode deposition thickness close to 100 nm exhibited minimal leakage current and yielded a highly stable output signal.

• Geomechanics and Engineering
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• v.32 no.6
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• pp.627-637
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• 2023

Volleyball is an international sport with many fans. This sport has made significant progress in schools and clubs. Volleyball is suitable for all age groups and can be used in different environments. It has many social and physical benefits. During the game provides special physical training for the players and is considered one of the most exciting games. Another type of volleyball is beach volleyball, a beach sport and one of the Olympic sports held on the sand with the same rules as volleyball. This sport is usually played in coastal areas, especially with wide sandy beaches. Because this sport is played in open spaces, the players stay in this space for a long time and are exposed to dangerous ultraviolet radiation. It is a wavelength of light in the range of electromagnetic waves with a wavelength between 10 and 400 nm. This wavelength is shorter than visible light and more protracted than X-ray. Ultraviolet (UV) rays are naturally present in sunlight and include about 10% of all waves emitted from the sun's surface. Prolonged exposure to ultraviolet light causes acute and chronic damage to the skin and vision and even destroys the entire immune system. Different covers of the earth's surface reflect different amounts of UV rays. For example, snow cover, sand, and seawater surface reflect this radiation. Therefore, the health of volleyball players is in danger due to this harmful radiation. This work aims to introduce a type of clothing made of nanoparticles that can repel ultraviolet rays and protect beach volleyball players whose health is at risk from this radiation.

• The Korean Journal of Rheology
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• v.3 no.1
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• pp.22-29
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• 1991

In an effort to predict the long term durability of carbon fiber/epoxy composites in a space environ-ment interlaminar shear strength (ILSS) of the composites was measured as a function of 0.5 MeV electron radiation dosage. For the ILSS measurements a notch method (ASTM D3846) was used with and without side-supports. the supports were used to prevent peeling or bending during the test. The ILSS of both T300/ 5209 longitudinal composite system increases monotonically with radiation when the test is corried out without the support the ILSS of the composites increases initially but then decreases with further radiation. It is also observed that the ILSS of the unsupported case is much lower than that of the supported case. Measurement of epoxy modulus shows that the elastic modulus increases monotonically with radiation. But the breaking strength of the epoxy decreases with radiation. Electron Spectroscopy for Chemcal Analysis shows that the oxygen contents at both the pure epoxy surface and the composite fracture surface increase with radiation dose resulting in the increase of polarity at the interfacial region. This may be a supporting evidence for the increase in the ILSS of the composites.