• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.983-991
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• 1992

This investigation is carried out numerically for the two dimensional natural convection and surface radiation heat transfer in a square enclosure. The bottom and top walls are isothermal at hot and cold temperatures respectively whereas the left and right side walls are adiabatic except a transparent window on the right side partially. The exchange of radiant energy is obtained by the net radiation method and the shape factor by the crossed string method. The changes in temperature and Nusselt number distributions of the walls due to the surface radiation and insolation are also investigated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.331-344
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• 1987

A numerical analysis has been conducted on the interaction of the thermal radiation and natural convection in a rectangular enclosure filled with a gray fluid. P-1 approximation is adopted for the radiative transfer and its application limit is examined. Considered are the Stark number effect, the optical thickness effect and the wall emissivity effect on the flow and heat transfer characteristics. As the Stark number increase or the optical thickness decreases, the boundary layer thickness and the flow velocity increase. Transition to turbulence is retarded with the increase of the radiation effect. When the optical thickness is one, the radiation effect is negligible for the Stark numbers larger than 10.

• Journal of the Korean Solar Energy Society
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• v.30 no.3
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• pp.71-80
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• 2010

This study carried out to understand the thermal characteristics of various surface material which compose the city through the observation in the summer. To examine passive cooling effect of planting of building, it is arranged four different materials that is natural grass, grass block, concrete slab and artificial grass. The results of this study are as follows; (1) Natural grass and grass block show the lower surface temperature because of the structures of leaf can do more thermal dissipation effectively. (2) There is little surface temperature between artificial grass and concrete. But there is little high surface temperature difference between natural grass and concrete because of latent heat effect. (3) The concrete can play a role of the tropical nights phenomenon as high heat capacity of concrete compare with other materials. (4) It is nearly same color in artificial grass and natural grass but there is large difference between natural grass and artificial grass at albedo. There is different albedo in near infrared ray range. (5) A short wave radiation gives more effect at the globe temperature than long wave radiation. (6) The artificial turf protected the slab surface temperature increase in spite of thin and low albedo materials.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1798-1806
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• 2020

In this study, we investigated whether there is a significant relationship between the natural radiation dose rate and the cancer incidences in Korea by using a big data analysis. The natural dose rate data for this analysis were the measurement data obtained from the 171 monitoring posts of the 113 administrative districts in Korea over the 10 years from 2007 to 2016. The relative cancer incidences for this analysis were the difference in the cancer patients per hundred thousand people year-on-year in the administrative districts with the five highest and the five lowest natural gamma dose rates each year over the same period. To analyze the correlation between the two variables, Spearman's rank correlation coefficient between the two rates was derived using R, a well-known big data analysis tool. The analysis showed that Spearman's rank correlation coefficient was more than 0.05 and that the correlation between the two variables was not statistically significant.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.174-177
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• 2003

Cooling load from the top plate to L$N_2$ surface, including wall conduction, gas conduction, radiation, and current leads, is investigated in a closed cooling system for HTS transformer. In general methods of load calculation, individual load is estimated separately, but they are actually coupled each other because of natural convection of nitrogen vapor. Using heat transfer analysis, we calculate cooling load with taking into account the effect of natural convection. Cooling load is under- estimated approximately 2 ％ when the natural convection is ignored. If the operating current is high, there will be a wide difference between actual cooling load and cooling load by individual calculation. Cooling load decreases with increasing number of radiation shield. With production, construction, and cooling load, three radiation shields are proper to 1 MVA HTS transformer.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.3
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• pp.217-232
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• 1992

A Numerical study on two-dimensional laminar natural convection with and without surface radiation in fully or partially open square cavity was performed. The cavity has one vertical heated wall facing a vertical opening and two horizontal insulated walls. The pressure boundary condition was applied to the opening instead of the velocity boundary condition. The results of this study showed that the increase of partition length decreased the convective and the radiative Nusselt numbers. It was also found that the increase of wall emissivity decreased the convective Nusselt numbers but increased the radiative Nusselt numbers.

• Journal of radiological science and technology
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• v.42 no.5
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• pp.379-385
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• 2019

Radiation is used for various purposes such as cancer therapy, research of industrial and drugs. However, in case of radiation accidents such as terrorism, collapsing nuclear plant by natural disasters like Fukushima in 2011, very high radiation does expose to human and could lead to death. For this reason, many people are concerning about radiation exposures. Therefore, assessment and research of retrospective radiation dose to human by various path is an necessary task to be continuously developed. Radiation exposure for workers in radiation fields can be generally measured using a personal exposure dosimeter such as TLD, OSLD. However, general people can't be measured radiation doses when they are exposed to radiation. And even if radiation fields workers, when they do not in possession personal dosimeter, they also can't be measured exposure dose immediately. In this study, we conduct retrospective research on reconstruction of dose after exposure by using smart chip card of personal items through Optically Stimulated Luminescence (OSL). The OSL signal of smart chip card shows linear response from 0.06 Gy to 15 Gy and results of fading rate 45 %, 48% for 24 and 48 hours due to the natural emission of radiation in sample, respectively. The minimum detectable limit (MDD) was 0.38 mGy. This values are expected to use as correction values for reconstruction of exposure dose.

• Journal of Korean Biological Nursing Science
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• v.4 no.2
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• pp.69-77
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• 2002

The purpose of this study was to identify the relationship of symptom distress and natural killer cell cytotoxicity in breast cancer patients who had been radiation therapy and/or chemotherapy after surgery. Symptom distress measured by modified Lee's(1994) physical symptom questionnaire. For measuring the natural killer cell cytotoxic activity. 8ml to 10ml blood was collected from the subjects. Mononuclear cell was isolated by centrifuge of the blood and cultured by putting $Cr^{51}$, and reacted with target cell, K562 cell. Amount of $Cr^{51}$ was measured, and %lysis was calculated. The results were as follows. 1) Symptom distress score was 42.18, which is moderate symptom distress. 2) Natural killer cell cytotoxic activities were 42.18%lysis(effector : target cell ratio=100 : 1) and 28.05%lysis(effector : target cell ratio=50 : 1). 3) Correlation coefficients of symptom distress and natural killer cell cytotoxic activity were $-.134{\sim}-.461$. Though significant correlation was not found between total score of symptom distress and natural killer cell cytotoxic activity, 3('pain' 'feel hot on radiation site' and 'difficulty in breathing') of 19 symptom distress items and natural killer cell cytotoxic activity showed significant negative correlation(p<.05). These findings suggest that 1) breast cancer patients who had been radiation therapy and/or chemotherapy after surgery have moderate symptom distress and decreased natural killer cell cytotoxic activity. 2) The symptom distress was not related to natural killer cell cytotoxic activity.

• Korean Journal of Veterinary Research
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• v.27 no.2
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• pp.185-189
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• 1987

The number of splenic lymphocyte, serum prostaglandin $E_2$ level and natural killer cell activity were assayed after single whole body irradiation of a sublethal dose of $^{60}Co-{\gamma}$ ray to C57BL/6J mice. With a view to knowing the relationships between radiation induced prostaglandin $E_2$ level and the normal natural killer cell activity after natural killer cell-target cell conjugation, The change of normal natural killer cell activity were measured by administration of prostaglandin $E_2$ containing serum from irradiated mice. The results were summarized as follows; 1. The total number of splenic lymphocyte was significantly decreased by irradiation and the number was not affected by indometacin, prostaglandin synthesis inhibitor, treatment. 2. Serum prostaglandin $E_2$ level was increased in irradiated mice, but indometacin treated mice group showed low level of prostaglandin $E_2$. 3. In the case of irradiated mice, natural killer cell activity was not shown any difference between irradiated group and indometacin combined group. But when natural killer cell-target cell conjugations were exposed to the serum of each group during cytotoxic activity assay, whereas the normal natural killer cell activity was significantly decreased by treatment of serum from irradiated mice, the activity was not changed by treatment of indometacin pretreated mice serum. This result indicated that the prostaglandin $E_2$ induced by the radiation inhibited the post-target binding cytolytic process of natural killer activity.

• Journal of the Korean Magnetic Resonance Society
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• v.5 no.1
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• pp.13-18
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• 2001

Natural alpha radiation produced a stable defect center to certain minerals. Electron Paramagnetic Resonance(EPR) spectroscopy is a powerful tool f3r quantifying this defect center. EPR method has been applied to trace alpha-radiation effect around the uranium ore deposit. The results show that EPR technique can be used to measure rapidly and nondestructively the defect center produced by natural alpha radiation. In general, a good correlation was achieved between defect center concentration and actinide elements(U, Th). These results imply that the concentration of defect center is dependent on the alpha radiation dose over long time scale.