• Journal of Magnetics
• /
• 제19권2호
• /
• pp.174-180
• /
• 2014

In this paper, a new and simple method is proposed to quickly estimate the induced electric field in the human child exposed to a 100 kHz-10 MHz magnetic field, for the sake of electromagnetic field (EMF) safety assessment. The quasi-static finite-difference time-domain (FDTD) method is used to calculate the induced electric fields in high resolution 3D human child models with various body size parameters, in order to derive the correction factor for the estimation equation. The calculations are repeated for various frequencies and incident angles of the magnetic field. Based on these calculation results, a new and simple estimation equation for the 99th percentile value of the body electric field is derived that depends on the body size parameters, and the incident magnetic field. The estimation errors were equal to or less than 5.1%, for all cases considered.

• 비파괴검사학회지
• /
• 제23권6호
• /
• pp.635-644
• /
• 2003

To ensure the reliability of ultrasonic nondestructive testing techniques for modern structural materials, the effects of anisotropy and inhomogeneity and the influence of non-planar component geometries on ultrasonic wave propagation have to be taken into account. In this article, fundamentals and applications of two analytical approaches to three-dimensional elastic beam field calculation are presented. Results for both isotropic materials including curved interfaces and for anisotropic media like composites are presented, covering field profiles for various types of transducers and the modeling of time-dependent rf-signals.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.151.1-151.1
• /
• 2014

Wake field effect on the electron beam from the undulator chamber in PAL-XFEL is analyzed. The wake field takeover some energy from the electron beam which will increase the energy spread of the electron beam. This will cause the degradation of the radiation power in PAL-XFEL. To decrease the effect, the surface of the undulator vacuum chamber should be fabricated with 200 nm surface roughness and 5 nm oxidation layer. In this presentation, the numerical calculation of the wake will be shown. Simulation results of the radiation generation in PAL-XFEL also will be presented.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.1987-1989
• /
• 2000

In this paper, electric field distribution of dielectric sphere considering surface or volume resistivity is analysed by the use of rotational symmetric charge simulation method. We applied three methods such as ${\alpha},{\beta}$ modified $\beta$ method to check electric field calculation error. We find f method and modified $\beta$ method are suitable to simulate volume and surface resistivity respectively.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.1510-1511
• /
• 2007

In this study quantifying techniques of ELF magnetic fields arising from currunt carrying indoor-conductor are proposed. These techniques can be applied to line-conductor with finite length and any configuration. Since each component of magnetic field in rectangular axes system is seperated, the resultant magnetic field can be caculated for multi-conductor system through these techniques.

• 한국전산유체공학회지
• /
• 제16권2호
• /
• pp.56-61
• /
• 2011

Numerical study is conducted to design the high temperature heat exchanger of Stirling engine by using the commercial CFD solver, FLUENT. The Fin-tube type of heat exchanger is designed as a reference model by considering the type of engine which is ${\beta}$-configuration. To find the optimal design of heat exchanger in heat transfer capacity numerical calculation is conducted by changing the shape, the number, and material of reference model in three-dimensional combustion field. Adjusted one-way constant velocity of working fluid that is helium is considered as the representative velocity of oscillating flow. The optimal design of heat exchanger considering the heat transfer capability is suggested by using the calculation results.

• 한국안전학회지
• /
• 제19권2호
• /
• pp.34-40
• /
• 2004

This paper presents an analysis of SAR(Specific Absorption Rate) distribution characteristics in a head model using FDTD(Finite Difference Time Domain). In this study human head was modelled in four elements-layered structure, consisting of skin, fat, skull and brain. To calculate the electromagnetic fields wihtin the head model, FDTD method was used. In the FDTD method, the electromagnetic wave is analyzed by solving a Maxwell's equations repeatedly. For the calculation, distance between power source and head model increased by 10[m]. Power density and incident electric field intensity were calculated. Based on the incident electric field, the program which calaculated internal electric fields intensity and SAR calculation of the head model were developed. The results of developed program using FDTD were compared with those of a commericial programs, which showed the availability and usefulness of the suggested scheme in this paper.

• KIEAE Journal
• /
• 제5권1호
• /
• pp.11-18
• /
• 2005

The optimized HVAC system design in tall buildings enable owners to save unnecessary energy consumption and residents to have comfort environments. The purpose of this study is to develop design process for optimized HVAC system design in tall buildings. As basic researches, literature researches and case studies of HVAC system design in tall buildings were performed. Survey was processed among expert in the field and key considerations on HVAC system design were drew as conclusions. With these conclusions, studies were performed on effects of wind velocity, outdoor air temperature, and solar radiation that are main factors of load calculation in tall buildings. Finally, air-tightness and stack effect were analyzed and estimated by literature studies, field measurements and computer simulations.

• The Journal of the Acoustical Society of Korea
• /
• 제21권3E호
• /
• pp.112-118
• /
• 2002

An unconstrained tuning fork with a 3-D model has been numerically analyzed by Finite Element Method (FEM) and Boundary Element Method (BEM). The first three natural frequencies were calculated by the FEM modal analysis. Then the trend of the change of the modal frequencies was examined with the variation of the tuning fork length and width. An formula for the natural frequencies-tuning fork length relationship were derived from the numerical analysis results. Finally the BEM was used for the sound pressure field calculation from the structural displacement data.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
• /
• pp.200-202
• /
• 2003

In this paper, Gauss filter function is used to filter the N-S equation and the subgrid-scale Reynold stresses model is introduced to deduce the practical form of LES equation for 2-D case for flow calculation of hydraulic machine. Then the LES equation and its discrete form in computational field are obtained in the body-fitted coordinate system and the numerical calculation program is built. The incompressible turbulent flow in double-flow-conduits-sewage pump impeller is computed by using the abovementioned program, and then the distribution rules of velocity and pressure in flow field are obtained. Based on this, the designs of double-flow-conduits-sewage pump impeller are optimized.