• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.584-590
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• 1994

A theoretical model has been developed to analyze the jet-edge interaction and the sound radiation. The edge responding to the sinuous impinging jet is regarded as an array of dipoles and their strength is determined by the boundary condition on the edge surface. The surface pressure distribution and the edgeforce are estimated using these dipoles. Then the pressure amplitude and directivity of the sound field is obtained by summing the radiating sounds from the dipole sources. It is found that the effective source is located a little distance downstream from the edge tip. And the directivity of the sound radiation is cardioid pattern near the edge but dipole pattern far from the edge. The theoretical model is confirmed by comparing the theoretical prediction of the edgeforce and sound pressure level with available experimental data.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.354-356
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• 2011

Renewable energy resources such as wind, wave, solar, micro hydro, tidal and biomass etc. are becoming importance stage by stage because of considering effect of the environment. Solar energy is one of the most successful sources of renewable energy for the production of electrical energy following solar energy. And, the solar/photovoltaic cell generators depend on the solar radiation, which is a random variable so this poses difficulty in the system scheduling and energy dispatching, as the schedule of the photovoltaic cell generators availability is not known in advance. This paper proposes to use the two-layered artificial neural networks for predicting the actual solar radiation from the previous values of the same variable.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.161-166
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• 2008

The major purpose of this paper is to develop an uncertainty estimate for the calibration of thermopile instruments used to measure solar radiation parameters. We briefly describe the solar radiation parameters most often measured, instrumentation, reference standards, and calibration techniques. The bulk of the paper describes elemental sources of error and their magnitude. We then apply a standard error analysis methodology to combine these elemental error estimates into a statement of total uncertainty for the instrument calibration factor. Our results allow one to evaluate the accuracy of a radiometric measurement using thermopile instrumentation in the light of the application, such as engineering test evaluation or for validation of theoretical models.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.7
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• pp.598-609
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• 1991

A generalized expression of radiation intensity from multiple non linear transmission lines is derived from the circuit model of radiation phenomena and the phased array antenna theory, for PC traces having independent signal sources. An adequacy of this proposed analitical method was verified comparing with computer simulation and experimental result for two and three non linear transmission lines feeded by 600 MHz signal.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.315-319
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• 2001

It is shown, that both cosmic radiation (external source) and natural radioactive gases (inner source) are sources of neutrons near the Earth crust. Correlation between the Earth crust dynamics and variations of thermal and slow neutron flux near the Earth surface is studied. It is shown, that variations of neutron flux near the Earth crust can be used for short-term predicting of natural hazards.

• Journal of Radiation Protection and Research
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• v.20 no.3
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• pp.155-162
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• 1995

The state-of-the art of detection and measurements of non-ionizing radiations are reviewed in relation to protection requirements, especially for electromagnetic and ultraviolet radiations. Dosimetric quantities, instruments and considerations needed for measurement are briefly explained. For electromagnetic radiation, the power density levels from various practical sources are summarized for reference uses. Large errors remain in the measurements of non-ionizinf radiations in general. Technical needs of development in measurement and dosimetry of non-ionizing radiations, therefore, are promissing when the increasing public concerns about the adverse health effects of non-ionizing radiations and proliferation of their uses are taken into account.

• The Journal of Engineering Research
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• v.3 no.1
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• pp.147-158
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• 1998

The purpose of thesis is to analyze the radiation characteristics of the parabola reflector antenna. The equivalent sources are used to compute the radiation fields in the far-zone utilizing the aperture integration. Using these results, we obtain the efficiency parameters associated with reflector : aperture efficiency, spillover efficiency, as the function of F/D, diameter beam squint angle and misarrangement.

• Journal of Conservation Science
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• v.36 no.4
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• pp.236-243
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• 2020

In this study, an accelerated aging experiment for fabric and paper was conducted using two light emitting diode(LED) sources with different wavelength characteristics, and the discoloration under each lighting type was examined. Hanji(Korean traditional paper) and related textiles showed more discoloration under blue LEDs, while the blue wool standard showed more discoloration under white LEDs. This, indicated that the deterioration varied depending on the sample color. The the effect of the light source on artifact deterioration was primarily related to the total radiation flux(expressed in mill watts), rather than the total luminous flux(expressed in lumens). In addition, the discoloration of the investigated artifacts was dependent on the color rendering of the lighting.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.50.1-50.1
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• 2016

The incorporation of radiation from massive stars is essential for modeling the dynamics and chemistry of star-forming clouds, yet it is a computationally demanding task for three-dimensional problems. We describe the implementation and tests of radiative transfer module due to point sources on a three-dimensional Cartesian grid in the Eulerian MHD code Athena. To solve the integral form of the radiation transfer equation, we adopt a widely-used long characteristics method with spatially adaptive ray tracing in which rays are split when sampling of cells becomes coarse. We use a completely asynchronous communication pattern between processors to accelerate transport of rays through a computational domain, a major source of performance bottleneck. The results of strong and weak scaling tests show that our code performs well with a large number of processors. We apply our radiation hydrodynamics code to some test problems involving dynamical expansion of HII regions.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.76-76
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• 2002

Purpose： The purpose of this study is to optimize the configuration of body RF coil composed of 4 planar subcoils for low field open MRI. Method： Our low field RE coil is composed of 4 subcoils assumed to be located at both the bottom and top sides of permanent magnet. Each subcoils has 3 main strips. The coil system has mirror inversion symmetry. First, the currents on the strips are obtained by inductance calculation and circuit analysis, Second, all the strips are divided into line strip elements across the strips, the self Inductances of line strip elements and the mutual inductances among the line strip elements are calculated, and current distributions of strip are obtained by circuit analysis, where each strip is considered as parallel combination of line strip elements. Finally all the line strip elements are segmented, magnetic field has been calculated by pseudo electric dipole radiation method, where the current elements are regarded as pseudo electric dipole radiation sources. We have performed above procedures for various configurations of RE coil. The field homogeneity is calculated in the 25 cm DSV.