• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1530-1535
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• 2011

Heat radiation of LED luminaires has risen a problem when applied indoor. LEDs can save energy with higher efficacy than other light sources. However, their heat radiation may increase power consumption for air-conditioning. Therefore, this paper carried out a comparative analysis on the amount of heat radiation for MR16, E26 bulb, and down-light which will be replaced to LED luminaires. Heat amount of LED-MR16 and LED-downlight was 48% and 87.5% lower than that of conventional lamps, halogen MR16 and E26 CFL, respectively. Consequently, the heat amount and indoor temperature were proportional to the power consumption of luminaire. Therefore, the use of LED luminaire can reduce the amount of heat radiation as well as power consumption.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.1
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• pp.146-154
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• 2001

In almost all real situations, there will be a radiant interchange between adjacent fins with the base surface as well as with the external environment. In the problem of this study, a rectangular fin is attached to a based. Our concern is whether the convective fin efficiency can be increased by the radiation heat exchanged between the fin and the base surface and how much. If the fin temperature toward the tip increased by the effect of radiation, the convective heat transfer increase due to the temperature difference between the ambient temperature and the surface temperature of the fin. If this true, the efficiency of the fin due to the radiation will increase. Attention is directed toward several parameters which have major roles on getting values of the fin efficiencies in several different values of parameters. Many different cases are, therefore, to be examined to have maximum fin efficiency by varying the values of each parameter.

• 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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.519-528
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• 1994

Degradation problem due to long term service in machine or structure is now one of important problems in whole industrial field. In this study, pressure vessel steel, Cr-Mo steel, which was used more than 60,000 hours, was surface-modified by laser beam radiation for the improvement of fatigue strength. To find out optimum radiation condition, hardness, residual stress measurement and fatigue tests were carried out with the specimen of different radiation conditions. Experimental results show that micro-hardness values on the surface of the radiated specimens were approximately 2.2 times higher than those of un-radiated ones. In the depth direction of the specimen, hardness on the surface showed maximum value and was decreased at the inside the specimen. Different hardness values are due to the energy density Q which was absorbed by the specimen. Fatigue tests show that fatigue life was improved by the compressive residual stress after laser beam radiation. However, some specimens with differednt conditions show the shorter fatigue life. It means that laser beam radiation with optimum parameter can improve thae fatigue strength.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.8
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• pp.800-807
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• 2012

In this paper, radiation efficiency of the plate surround by an infinite rigid baffle is studied. The plate is simply supported and one side is in contact with air, while other side with water. The pressure and normal velocity over the plate surface are assumed as modal summations, from which a set of linear equations is obtained for fluid-structure coupled problem. It is shown that neglect of the cross modes results in overestimation of the radiation efficiency specifically for mid-frequency ranges. Based on the fact that the responses are mainly determined from the first few cross modes in addition to the diagonal terms, a new algorithm is proposed, where banded matrix is iteratively solved in computing radiation efficiency. In numerical examples, it is found that radiation efficiency obtained from banded matrix is in excellent agreement with the one from the full matrix, while computing time is significantly reduced. It is also found that as frequency grows larger, radiation efficiency considering only diagonal terms is a good approximation.

• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.199-205
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• 2004

We have developed a composite grid method for the solution of the radiation problem We divide the domain into two different grids; one is a moving grid system and the other is a fixed grid system. This numerical method is applied to calculation of the radiation forces generated by the submerged plate oscillating near a free surface. The experimental data are compared with the numerical ones obtained by the present method and a linear potential theory. As a result, we can confirm the accuracy of the present method. Finally, Lie have evaluated the effect of nonlinear and viscous damping on the hydrodynamic forces acting on the submerged plate.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.1
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• pp.37-43
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• 2015

This paper presents a detailed procedure for a nonlinear soil-structure interaction of a seismically isolated NPP(Nuclear Power Plant) structure using the boundary reaction method (BRM). The BRM offers a two-step method as follows: (1) the calculation of boundary reaction forces in the frequency domain on an interface of linear and nonlinear regions, (2) solving the wave radiation problem subjected to the boundary reaction forces in the time domain. For the purpose of calculating the boundary reaction forces at the base of the isolator, the KIESSI-3D program is employed in this study to solve soil-foundation interaction problem subjected to vertically incident seismic waves. Wave radiation analysis is also employed, in which the nonlinear structure and the linear soil region are modeled by finite elements and energy absorbing elements on the outer model boundary using a general purpose nonlinear FE program. In this study, the MIDAS/Civil program is employed for modeling the wave radiation problem. In order to absorb the outgoing elastic waves to the unbounded soil region, spring and viscous-damper elements are used at the outer FE boundary. The BRM technique utilizing KIESSI-3D and MIDAS/Civil programs is verified using a linear soil-structure analysis problem. Finally the method is applied to nonlinear seismic analysis of a base-isolated NPP structure. The results show that BRM can effectively be applied to nonlinear soil-structure interaction problems.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.297-299
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• 2015

In this paper we have examined the linear stability of triangular equilibrium points in the photogravitational restricted three body problem when both primaries are triaxial rigid bodies, the bigger one an oblate spheroid and source of radiation. The orbits about the Lagrangian equilibrium points are important for scientific investigation. A number of space missions have been completed and some are being proposed by various space agencies. We analyze the periodic motion in the neighbourhood of the Lagrangian equilibrium points as a function of the value of the mass parameter. Periodic orbits of an infinitesimal mass in the vicinity of the equilibrium points are studied analytically and numerically. The linear stability of triangular equilibrium points in the photogravitational restricted three body problem with Poynting-Robertson drag when both primaries are oblate spheroids has been examined by A. Kumar (2007). We have found the equations of motion and triangular equilibrium points for our problem. With the help of the characteristic equation we have discussed stability conditions. Finally, triangular equilibrium points are stable in the linear sense. It is further seen that the triangular points have long or short periodic elliptical orbits in the same range of ${\mu}$.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.815-824
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• 2022

The current radiation safety management system is also applied to radiation practices at universities. The application of the law raised concerns about poor radiation practice education and hindering the development of radiology. Accordingly, the Korean Radiology Professors Association needed to grasp the reality of the management system for radiation practice education at each university and the current radiation safety management system in the department of Radiological science. So, a survey was conducted on heads of radiological science departments across the country. Through the survey, it was found that the current application of the Nuclear Safety Act to radiation safety management in the department of Radiological science is excessively restrictive and not very effective. In addition, radiology practice education for the purpose of training health and medical professionals should be controlled by the Ministry of Health and Welfare and the Korea Centers for Disease Control, but there is a problem of being supervised by the Nuclear Safety and Security Commission. Therefore, in this study, as a legal improvement plan to solve this problem, first, a plan according to a partial amendment to the Higher Education Act, second, a plan to be supervised by the Ministry of Health and Welfare through the amendment of article 37 of the Medical Service Act, third, article 20-2 of the Enforcement Decree of the Medical Service Technologists Act was newly inserted to propose three measures to be supervised by the Ministry of Health and Welfare.

• Archives of Plastic Surgery
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• v.38 no.6
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• pp.803-807
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• 2011

Purpose: The safety of radiation therapy after breast reconstruction using transverse rectus abdominis myocutaneous (TRAM) flap is still being debated, and few studies exist on the outcome of irradiation after immediate TRAM breast reconstruction. Some authors presented satisfactory outcomes after adjuvant radiation therapy on reconstructed breast with pedicled TRAM flap, while others reported significant post radiation changes of the flap. Effect of radiation therapy on TRAM flap was evaluated to see whether adjuvant radiation therapy was tolerable. Methods: 1000 immediate TRAM breast reconstruction was done by a single surgeon from July, 2001 to December, 2009. Among them 105 patients required adjuvant radiation therapy because of advanced disease or locoregional recurrence. Fat necrosis, radiation fibrosis, mastectomy skin flap necrosis, need for secondary touch up procedures, patient satisfaction were evaluated. Results: The incidence of fat necrosis was 10.5% and significant radiation fibrosis occurred in only one patient. Delayed wound problem did not occur during or after irradiation. Secondary touch-up procedures were performed in 12.3%, the most common being fat graft (8.6%). Average patient satisfaction score was 8.62/10, which was not significantly different from the authors' previous report involving all the TRAM patients (8.50). Conclusion: Radiation therapy did not increase the complication rate significantly. Aesthetic result was affected but was tolerated in most cases. The fear of adjuvant radiation is not a negative factor in selecting immediate breast reconstruction with TRAM flap.