전자파 환경의 전자기장 방출과 그 영향에 대한 고찰

윤광렬 한국전자통신학회 2019 한국전자통신학회 논문지 Vol.14 No.3

EMF (Electromagnetic Field) is a valuable resource for living in a knowledge-based information society. EMF is used in home appliances that make our lives easy and convenient, and in telecommunication devices such as mobile phones, personal computers, medical devices and broadcasting towers. However, the biological hazards associated with EMF exposure are also increasing in signal from telecommunication devices. Studies of the effects of EMF exposure on humans have been conducted for a long time, but it has not yet been demonstrated whether the EMF effect is harmful. In this paper, we examine the electromagnetic field emitted from various electronic devices around living and its effect. EMF (전자기장)는 지식 기반 정보 사회에서 살기위한 귀중한 자원 중 하나다. EMF는 우리의 삶을 쉽고 편리하게 만들어주는 가전제품과 휴대 전화, 개인용 컴퓨터, 의료 기기 및 방송 타워 등의 정보 통신 기기에 사용된다. 그러나 EMF 노출과 관련된 생물학적 유해성은 전기 통신 장치로부터의 신호도 증가하고 있다. 인체에 대한 EMF 노출의 영향에 대한 연구가 오랫동안 수행되었지만 EMF 효과가 유해한 지 여부는 아직 증명되지 않았다. 본 논문에서는 생활주변의 각종 전자기기로부터 방출 되는 전자장과 그 영향에 대해서 고찰한다.

주사전자 현미경의 전자렌즈 설계 및 해석

정현우(H. U. Jung),박만진(M. J. Park),박근(K. Park),김동환(D. H. Kim),장동영(D. Y. Jang) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11

The scanning electron microscope (SEM) is one of the most popular instruments available for the measurement and analysis of the micro/nano structures. It is equipped with an electron optical system that consists of an electron beam source, magnetic lenses, apertures, deflection coils, and a detector. The magnetic lenses play a role in refracting electron beams to obtain a focused spot using the magnetic field driven by an electric current from a coil. A SEM column usually contains two condenser lenses and an objective lens. The condenser lenses generate a magnetic field that forces the electron beams to form crossovers at desired locations. The objective lens then focuses the electron beams on the specimen. The present work concerns finite element analysis for the electron magnetic lenses so as to analyze their magnetic characteristics. To improve the performance of the magnetic lenses, the effect of the excitation current and polepiece design on the amount of resulting magnetic fields and their peak locations are analyzed through the finite element analysis.

전계방출 주사전자 현미경의 전자광학계 수치해석

박근(Keun Park),박만진(Man-Jin Park),김동환(Dong-Hwan Kim),장동영(Dong-Young Jang) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

A scanning electron microscope (SEM) is well known as a measurement and analysis equipment in nano technology, being widely used as a crucial one in measuring objects or analyzing chemical components. It is equipped with an electron optical system that consists of an electron beam source, electromagnetic lenses, and a detector. The present work concerns numerical analysis for the electron optical system so as to facilitate design of each component. Through the numerical analysis, we investigate trajectories of electron beams emitted from a nano-scale field emission tip, and compare the result with that of experimental observations. Effects of various components such as electromagnetic lenses and an aperture are also discussed.

Free-Electron Two-Quantum Stark Radiation in a Pre-Bunched Magnetic-Wiggler Free-Electron Laser

Shang Kim 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.6

We study the effects of pre-bunching of the electron beam in a free-electron laser. The pre-bunching is necessarily associated with an electric wiggler which can drive both spontaneous and net stimulated free-electron two-quantum Stark (FETQS) radiation. We find that the radiations from the electrons cannot be made to interfere coherently in the practical sence. We derive the power of spontaneous FETQS emission, the laser gain due to net stimulated FETQS emission and the cross section of electric-wiggler-enhanced three-quantum (EWETQ) scattering with quantum-wiggler electrodynamics. We find that EWETQ scattering can be ignored. From the fact that the uncertainty in the electron position in the electron beam is on the order of the mean inter-electron distance and Heisenberg's uncertainty principle, the maximum power of spontaneous emission from an electron is formulated. Based on this formulation, the recently-recognized laws for the lower and upper limits of the constant-amplification region of laser intensity and the above derived spontaneous radiation-power and gain value in the constant-gain region, we find the following: When the current density is small, the laser intensity cannot arrive by spontaneous FETQS emission to the threshold level above which the laser radiation can keep the electron distribution being a Maxwellian distribution for constant amplification. When the current density is suffiently high such that the laser intensity can arrive at the threshold level by spontaneous FETQS emission, amplification by net stimulated FETQS emission still cannot occur because the threshold level is higher than the plateau level above which net stimulated FETQS emission cannot take place. However, in this case, amplification can be made to take place by reducing the strength of the magnetic wiggler after the laser intensity arrives at the threshold level.

Module level EMC verification method for replacement items in nuclear power plant

Hee-Taek Lim,Moon-Gi Min,Hyun-Ki Kim,Gwang-Hyun Lee,Chae-Hyun Yang Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

Internal replaceable electronic module substitutions can impact EMC (ElectroMagnetic Compatibility) qualification testing and results if EMC testing is conducted at the cabinet level. The impact of component substitutions on EMC qualification results therefore should be evaluated. If a qualitative evaluation is not adequate to ensure that the modified product will not impact the cabinet level EMC qualification results, a new qualification testing should be conducted. Component level retesting should be conducted under electromagnetically equivalent conditions with the cabinet level test. This paper analyzes the propagation of conducted susceptibility test waveforms in a representative cabinet and evaluates the impact of component substitutions on cabinet level EMC qualification results according to the location of the replacement items. A guideline for a qualitative evaluation of the impact of component substitutions is described based on the propagation of the conducted susceptibility test waveforms. A module level test method is also described based on an analysis of the shielding effectiveness of the cabinet.

Development of PET Detector for Localization Using MLPE Based on Simulation Data

Seung-Jae Lee,Byungdu Jo,Sun-Young Cho 한국자기학회 2023 Journal of Magnetics Vol.28 No.4

In order to measure the position of the scintillation pixel of the positron emission tomography (PET) detector module, it is necessary to obtain a flood image through a radiation source and then perform a segmentation process of each scintillation pixel area in the flood image. Without performing this process, a method of reading the scintillation pixel position using simulation data was developed. It was difficult to directly apply the data obtained through simulation to the experimental data since simulation data and experimental data cannot be directly matched. In this study, the Anger data of four channels obtained from the detector module composed of simulation were calculated at the ratio according to the channel and applied to the experimental data. Through simulation, a look-up table (LUT) for each scintillation pixel was prepared, and the position of the scintillation pixel where the gamma ray event occurred was measured using the experimental data and the maximum likelihood position estimation (MLPE). The measurement result showed an accuracy of 94.4 %. If these study results are introduced into the PET detector module, the position of the scintillation pixel can be read quickly and conveniently without changing the existing system.