• Economic and Environmental Geology
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• v.32 no.3
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• pp.273-280
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• 1999

In order to protect inhabitans' health and to collect data for prediction of the effcts from accidental emission of rasioactive materials from nuclear power plant, exposed dose rate be monitored within the limit dose rate. This research was carried out to investigate the accumulation of environmental radioactivity around Younggwang Nuclear Power Plant, and to infer and in infer and assay the additional exposed dose rate of inhabitants in Younggwang site from the operation of nuclear plant operation. External radiation dose rate, radiation environmental samples, and exposed dose rate of inhabitants in Younggwang site were investigated for estimaing environment activity in the vicinity of the nuclear power plant area. For the external radiation dose rate, the result showed that range of normal variation was found and any artificial radioisotope was not deteted in the analysis of environmental samples. Exposed dose rate of inhabitants was lower than 0.4% of the limit value of ICRP and it may be concluded that there was no effect on inhabitants and environment from the operation of nuclear power plant.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.836-842
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• 2001

The more sophisticated patterns of propagation model is presented in this paper, which includes three different source characteristics. The spherical, cosine and dipole radiation characteristics compared and sound event level and the maximum sound level are calculated by experiment and calculation. It is shown that patterns of propagation has dipole characteristics for low speed range(below about 150km/h) at electric multiple system. We know that push-pull high speed system(maximum speed: 300km/h) has cosine characteristics of noise propagation. For this purpose, We conduct the experiment of noise and know the empirical formula of noise level and radiation coefficient K. This model of simulation is conducted through point source array model at wheel/rail contact point by using program and experimental formula. We can guess prediction of profile, flat and wear of wheel by above modeling in near field.

• Journal of Mechanical Science and Technology
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• v.14 no.12
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• pp.1403-1411
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• 2000

Heat losses from the receivers for a dish-type solar energy collecting system constructed at Korea Institute of Energy Research are analyzed. The Stine and McDonald's model is used to estimate the convection loss. The Net Radiation method and the Monte-Carlo method are used to calculate the radiation heat transfer rate from the inside surface of the receiver to the surroundings. Two different receivers are suggested here and the performances of the receivers are estimated and compared with each other based on the prediction of the amount of heat losses from the receivers. The effects of the receiver shape and the radiation properties of the surface on the thermal performance are investigated. The performance of Receiver I is better than that of Receiver II, and the amount of solar irradiation that is not captured by the captured by the receiver after being reflected by the concentrator becomes significant if the temperature of the working fluid is low.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.2 s.95
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• pp.225-231
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• 2005

This paper presents a design method for the structural-acoustic coupled radiator that can emit sound in the desired direction. A coupled system that has a finite space and a semi-infinite space separated by two flexible walls and an opening is considered. An objective function is selected to maximize radiation power on a main axis and minimize a side lobe level. To get initial values, prediction of a pressure distribution on field points and radiation pattern of the structural-acoustic coupling system is shown at a coupled-resonant frequency. Three different optimization methods are adapted to design the coupled radiator. Pressure and intensity distribution of the designed radiator is presented.

• International Journal of Automotive Technology
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• v.2 no.1
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• pp.33-38
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• 2001

The noise generated from a treadband mechanism of a tire has been the subject of this research. In particular, the treadband has been treated as an infinite tensioned beam resting on an elastic foundation which includes damping. The main objective is here to predict the sound power generated from a system mentioned above by locating harmonic point forces representing the excitation of treadband at the contact patch. It is possible to predict the sound power radiated from this structure by wavenumber transformation techniques. To find out the minimum radiated sound power, All parameters were varied. Thus this model can be used as a tire design guide for selecting parameters which produce the minimum noise radiation.

• The Journal of the Acoustical Society of Korea
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• v.2 no.1
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• pp.48-58
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• 1983

The transient sound radiation from the impact between a steel ball and a thick plate is analyzed theoretically and compared with experiment results. The derivation process itself is difficult to analyze sound radiation characteristics theoretically for a thick plate with some resonances but may be investigated from measured data. During mechanical impacts, arbitrary driving point importance for an elastic system enables to predict by using mechanical importance method. In order to obtain approximate solution for an impact model testing, the surface Helmholtz integral formulation based on the integral expression for pressure in the field in terms of surface pressure and normal velocity is used as a basis. A simple expression is developed for an impulsive response function, which is time dependent velocity potential and pressure for an impact may then be computed by a convolution of exciting force. In estimating of elastic-acoustical correlation problems, mechanical inertance, overall transfer function and radiation resistance obtained by signal processing techniques are used. The usefulness is confirmed by applying these methods prediction of arbitray driving pint inertance, radiated sound pressure and exciting force.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.27-32
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• 2011

Most of domestic building generally don't have fixed shading devices considering of appearance and aesthetic issues. In this study is suggested that tilt window simultaneously has a role of shading and blocking solar radiation. The tilt window thermal performance is investigated by relation ship between inclination and heating cooling road. As comparing vertical window with $5^{\circ}$ and $7^{\circ}$ of tilt window respectively, the heating load is increased by 3.6% and cooling load is reduced by 8.1% on $5^{\circ}$ tilt window and the heating load is increased by 5.3% and cooling load is reduced by 11.5% on $5^{\circ}$ tilt window. Especially, the total load of alternative tilt window is showed the reduction rate 2.6% and3.6% compared of vertical window. Therefore, the tilt window is possible to role of shading of solar radiation and reduction of heating and cooling load.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.257-261
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• 2004

Computational fluid dynamics analysis was carried out for thermo-chemical flow field in Arcjet thruster with mono-propellant Hydrazine ($N_2$H$_4$) as a working fluid. The theoretical formulation is based on the Reynolds Averaged Navier-Stokes equations for compressible flows with thermal radiation. The electric potential field governed by Maxwell equation is loosely coupled with the fluid dynamics equations through the Ohm heating and Lorentz force. Chemical reactions were assumed being infinitely fast due to the high temperature field inside the arcjet thruster. An equilibrium chemistry module for nitrogen-hydrogen mixture and a thermal radiation module for optically thin media were incorporated with the fluid dynamics code. Thermo-physical process inside the arcjet thruster was understood from the flow field results and the performance prediction shows that the thrust force is increased by amount of 3 times with 0.6KW arc heating.

• Journal of Environmental Impact Assessment
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• v.23 no.1
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• pp.29-37
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• 2014

Exact and precise noise measurement is the basis for the reduction measure R&D, impact assessment and prediction modeling for railway noise. In this study, research trend as well as national and international noise measurement standard are investigated. For the estimation of vertical radiation characteristics of railway noise, specially devised zig was used. From the noise measurement and analysis, exact noise height radiated from the railway was characterized. The obtained results will be used for the suggestion of the height of microphone position of railway noise measurements.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.638-644
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• 2017

The importance of developing a source-term assessment technology has been emphasized owing to the decommissioning of Kori nuclear power plant (NPP) Unit 1 and the increase of deteriorated NPPs. We analyzed the behavioral mechanism of corrosion products in the primary system of a pressurized heavy-water reactor-type NPP. In addition, to check the possibility of applying the CRUDTRAN code to a Canadian Deuterium Uranium Reactor (CANDU)-type NPP, the type was assessed using collected domestic onsite data. With the assessment results, it was possible to predict trends according to operating cycles. Values estimated using the code were similar to the measured values. The results of this study are expected to be used to manage the radiation exposures of operators in high-radiation areas and to predict decommissioning processes in the primary system.