• Journal of the Korea Institute of Building Construction
• /
• v.12 no.5
• /
• pp.478-489
• /
• 2012

Each year, about four million tons of steel slag, a by-product produced during the manufacture of steel by refining pig iron in the converter furnace, is generated. It is difficult to recycle this steel slag as aggregate for concrete because the reaction with water and free-CaO in steel slag results in a volume expansion that leads to cracking. However, the steel slag used in this study is atomized using an air-jet method, which rapidly changes the melting substance at high temperature into a solid at a room temperature and prevents free-CaO from being generated in steel slag. This rapidly-cooled steel slag has a spherical shape and is even heavier than natural aggregate, making it suitable for the aggregate of radiation shielding concrete. This study deals with the radiation shielding property of concrete that uses the rapidly-cooled steel slag from the oxidizing process in the converter furnace as fine aggregate. It was shown that the radiation shielding performance of concrete mixed with rapidly-cooled steel slag is even more superior than that of ordinary concrete.

• Journal of Radiation Industry
• /
• v.5 no.3
• /
• pp.249-252
• /
• 2011

Lignin is one of the natural macromolecules. Every year large amount of lignin arises from the cellulose production as a by-product worldwide. The use of lignin as a precursor to carbonaceous materials has gained interest due to its low cost and high availability. Therefore, we improved the properties of alkali-lignin by exposing to gamma ray in this study. The alkali-lignin is irradiated by Gamma ray irradiation with varying doses. The char yields of alkali-lignin were investigated by increasing up to 50 kGy. The cross-linking and bond scission of alkali-lignin occur simultaneously during gamma ray irradiation. The crosslinking was predominantly accelerated by gamma ray irradiation up to 50 kGy. Bond scission predominantly occurs between 50 and 500 kGy. ESCA analysis indicated that the alcoholic carbon increase up to 50 kGy. Solution viscosity was increased as absorbed dose increased up to 20 kGy. In addition, the aromatic ring was not influenced by irradiation at doses ranging from 20 to 500 kGy as shown in FT-IR results.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.10
• /
• pp.1807-1813
• /
• 2007

This paper deals with extending the variable natural oscillation frequency range of an active integrated FET oscillator. In this paper, we conform experimentally that the variable range of the natural oscillation frequency is expanded about three times in the oscillator controlled by the varactor diode. When the frequency difference is given to the oscillators in the two element antenna system, phase difference appeared between the oscillators. The 2-, 3-, 4-, 5-element patch antenna arrays are composed for the beam scanning experiments. All the above patch antennas show good phased array characteristics. The range of the scanning angle is about $30^{\circ}$, and the radiation power is gradually increased from $50{\mu}W\;to\;200{\mu}W$. The radiation patterns we sharpened as the number of elements is increased.

• Structural Engineering and Mechanics
• /
• v.64 no.1
• /
• pp.93-107
• /
• 2017

The article presents the vibration and acoustic responses of un-baffled doubly curved laminated composite panel structure under the excitation of a harmonic point load. The structural responses are obtained using a simulation model via ANSYS including the effect various geometries (cylindrical, elliptical, spherical and hyperboloid). Initially, the model has been established by solving adequate number of available examples to show the convergence and comparison behaviour of the natural frequencies. Further, the acoustic responses are obtained using an indirect boundary element approach for the coupled fluid-structure analysis in LMS Virtual.lab by importing the natural frequency values. Subsequently, the values for the sound power level are computed using the present numerical model and compared with that of the available published results and in-house experimentally obtained data. Further, the acoustic responses (mean-square velocity, radiation efficiency and sound power level) of the doubly curved layered structures are evaluated using the current simulation model via several numerical experimentations for different structural parameters and corresponding discussions are provided in detail.

• Journal of the Korean Solar Energy Society
• /
• v.21 no.2
• /
• pp.35-43
• /
• 2001

The results of numerical simulation on the performance of a solar chimney system in building are described. The inside surface temperature of four walls within the solar chimney arc calculated with solar radiation and outdoor temperature in summer. The air within the solar chimney is heated by conduction, convection and radiation. Air temperature distribution from the bottom to the top and outlet air temperature can be obtained by solving energy balance equation. Since the buoyance or stack effect is affected by temperature difference between the bottom and the top within the solar chimney. It is evaluated using inlet and outlet temperatures. It is expected that natural ventilation by the solar chimney of witch the height is 7.8m and the cross sectional area is $4.93m^2$ can provide about $6400m^3/h$ on sunny day.

• BMB Reports
• /
• v.47 no.4
• /
• pp.209-214
• /
• 2014

Ultraviolet B (UVB) radiation induces the production of reactive oxygen species (ROS) that promote apoptotic cell death. We showed that cytosolic $NADP^+$-dependent isocitrate dehydrogenase (IDPc) plays an essential role in the control of cellular redox balance and defense against oxidative damage, by supplying NADPH for antioxidant systems. In this study, we demonstrated that knockdown of IDPc expression by RNA interference enhances UVB-induced apoptosis of immortalized human HaCaT keratinocytes. This effect manifested as DNA fragmentation, changes in cellular redox status, mitochondrial dysfunction, and modulation of apoptotic marker expression. Based on our findings, we suggest that attenuation of IDPc expression may protect skin from UVB-mediated damage, by inducing the apoptosis of UV-damaged cells.

• Journal of the Korean Society of Industry Convergence
• /
• v.8 no.2
• /
• pp.105-112
• /
• 2005

The characteristics of natural convection heat transfer combined with radiation in a vertical parallel plates has been investigated experimentally. The vertical channel is consisted with a heated wall and three protruding heating sources attached on the opposite wall. The cooling of modules has been experimented with heating the wall as well as modules themselves at different aspects ratios and heating fluxes. As the location of module is higher, the temperature becomes higher, but the increasement is smaller. When the aspect ratio is lower than 26, its effect on the temperature is not significant rather than that of the radiation heat transfer. Furthermore, the correlation of Nusselt number with the Rayleigh number are attempted, but additional treatment is needed to accomodate the cases of heating module and/or opposite wall.

• Journal of Radiation Protection and Research
• /
• v.13 no.1
• /
• pp.1-7
• /
• 1988

A bubble-damage polymer detector, which operation principles are based on vaporization of superheated liquid drops by interaction with radiations, is developed for neutron dosimetry. The detectors are fabricated by dispersing the superheated liquid drops of Freon12 into transparent and elastic polymer made of acylamide and glycerine. The bubbles formed by neutron irradiation are immediately visible. The neutron sensitivity of the detectors is 4-7 bubbles/10$\mu$ Sv for Am-Be neutrons.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.30 no.1
• /
• pp.117-122
• /
• 2004

Exessive UV radiation causes a lot of problems in our skin. In order to find out the alternative UV absorber that can safely be used in cosmetics, we have screened various natural extracts in terms of their UV absorbing effect. Some natural extracts, which possess antioxidative activities, have also been found to retard the oxidation process in our experiment. Natural compound such as 7-hydroxycymopol, baicalein, etc. could be transformed into adjuvant UV absorber by chemical modification. In cosmetics, its chemical stability against UV radiation, exposure to oxygen and other factors could be improved by using the silicone or W/S type emulsion. The values of MED (minimal erythema dose) were improved to 0.10 ${\pm}$ 0.02∼0.11 ${\pm}$ 0.02 by adding this natural extract into the cosmetic formulations. In conclusion, the results of the present study show that natural extracts could be used as an adjuvant UV absorber, if they are stabilized.

• Journal of the Mineralogical Society of Korea
• /
• v.10 no.2
• /
• pp.75-81
• /
• 1997

High pressure X-ray diffraction study was carried out on a natural FeO(OH)-goethite to investigate its compressibility at room temperature. Energy dispersive X-ray diffraction method was employed using Mao-Bell type diamond anvil cell with Synchrotron Radiation. MgO powder was compressed together with goethite for the high pressure determinations. Bulk modullus was determined to be 147.9 GPa by the Birch-Murnaghan equation of state under assumption of K0' of 4. This value was subjected to compare with its structural analogs and related materials.