• 기계와재료
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• v.23 no.3
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• pp.30-47
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• 2011

전자기 성형 공정은 강한 전이 자기장을 가공하고자 하는 금속에 직접 작용시켜 금속을 변형시키는 가공 기술로 최근 난성형성 소재의 성형 및 이종 소재의 접합 등에 장점을 가지고 있어 관심이 높아지고 있다. 또한, 전자기 성형 공정을 기존의 스템핑, 하이드로포밍과 같은 성형 공정의 단점을 보완하는 공정으로 이용하여 자동차 부품에 적용하려는 연구가 시도되고 있다. 전기, 자기, 열, 변형을 포함하는 복잡한 물리 현상이 관련되어 있는 전자기 성형 공정을 모사하기 위해서 각 물리 현상들을 연계하여 수치적으로 계산해 내는 기술에 대한 연구가 다각도로 진행 중이다. 본 고에서는 전자기 성형 기술에 대한 개념과 최신 국내외 기술 동향을 소개한 후, 전자기 성형의 수치 해석 기술에 대한 연구 동향을 정리하였다.

• Journal of Radiation Protection and Research
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• v.35 no.3
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• pp.124-134
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• 2010

The Geant4 simulation toolkit provides improved or renewed physics model according to the version. The latest Geant4.9.3 which has been recoded by developers applies inserted Livermore data and renewed physics model to the low energy electromagnetic physics model. And also, Geant4.9.3 improved the physics factors by modified code. In this study, the stopping power and CSDA(Continuously Slowing Down Approximation) range data of electron or particles were acquired in various material and then, these data were compared with NIST(National Institute of Standards and Technology) data. Through comparison between data of Geant4 simulation and NIST, the improvement of physics model on low energy electromagnetic of Geant4.9.3 was evaluated by comparing the Geant4.9.2.

• Progress in Medical Physics
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• v.20 no.4
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• pp.225-234
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• 2009

Geant4 (GEometry ANd Tracking) provides various packages specialized in modeling electromagnetic interactions. The validation of Geant4 physics models is a significant issue for the applications of Geant4 based simulation in medical physics. The purpose of this study is to evaluate accuracy of Geant4 electromagnetic physics for proton therapy. The validation was performed both the Continuous slowing down approximation (CSDA) range and the stopping power. In each test, the reliability of the electromagnetic models in a selected group of materials was evaluated such as water, bone, adipose tissue and various atomic elements. Results of Geant4 simulation were compared with the National Institute of Standards and Technology (NIST) reference data. As results of comparison about water, bone and adipose tissue, average percent difference of CSDA range were presented 1.0%, 1.4% and 1.4%, respectively. Average percent difference of stopping power were presented 0.7%, 1.0% and 1.3%, respectively. The data were analyzed through the kolmogorov-smirnov Goodness-of-Fit statistical analysis test. All the results from electromagnetic models showed a good agreement with the reference data, where all the corresponding p-values are higher than the confidence level $\alpha=0.05$ set.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.67-70
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• 2009

송수신기 일체형인 소형 루프 시스템을 해저 전자탐사 기술의 적용 가능을 확인하는 과정의 시작 단계로 자기 쌍극자 송신원을 이용한 층서구조에서의 전자가 반응을 계산 하였다. 전도성인 해양 환경에서 측정되는 신호의 크기가 작은 한계가 있지만 전자기장 반응 해석을 통행 지하 하부의 정보를 얻을 수 있었다. 기반암 위의 층이 바닷물보다 저항성인 해저 지각인 경우와 전도성인 열수광상인 경우에 따라 반응이 달라짐을 확인하였고, 그 층의 두께에 따라서 변화하는 전자기 반응을 계산하여 탐지 가능한 층의 두께를 예상할 수 있었다. 송수신기가 모두 바다 속에 위치하기 때문에 송수신기의 배치 방법과 송수신기가 해저면에서 떨어지게 될 때 신호의 반응 변화를 파악하였다. 해양 소형 루프 전자탐사의 실제 적용을 위해서 이상의 연구들이 기초가 될 것으로 기대된다.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.74-82
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• 2013

This paper deals with a single stage coilgun which is a variety of EML(ElectroMagnetic Launcher) and can be applied to launching a small satellite. We propose a mathematical and physical model in order to design a single stage coilgun and study physical characteristics related to design parameters. A proposed mathematical and physical model is verified by electromagnetic FEM software FEMM 4.2.

• Geophysics and Geophysical Exploration
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• v.21 no.4
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• pp.244-254
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• 2018

The first geophysical technique applied to the agricultural sector in Korea was electrical resistivity sounding and conducted in purpose of groundwater exploitation in the 1970s. According to the diversity of agricultural activities since the 1990s, various geophysical methods including electrical resistivity, electromagnetic induction, and self-potential method were applied to several agricultural fields such as soil characterization with saline concentration in vast reclaimed area, delineation of seawater intrusion regions in costal aquifer, safety inspection of embankment dikes with leakage problem, detection of ground subsidence from overpumping and tracing of groundwater aquifer contamination by leachate from livestock mortality burial or waste burial site. This paper introduces representative geophysical techniques that have been utilized in various agricultural fields and suggests several ways to develop the geophysical methods required for the precision agriculture field in the near future based on the past achievements.

• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.81-83
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• 2009

• Journal of the Korean Vacuum Society
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• v.21 no.2
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• pp.69-77
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• 2012

Visualization of the electromagnetic vector fields are presented and examined with Mathematica. Vector fields may be used to represent a great of many physical quantities in various area of physics, including electromagnetism with vector differential operators. Because they deal with abstract, three-dimensional fields that are some times very difficult to visualize, electromagnetism can be conceptually rather difficult. Visual representation of such an abstract vector fields is invaluable to student or researchers working in this field and also helps teaching electromagnetism to physics or engineering students. Mathematica provides a wider range of graphical tools including plot of vector fields and vector analysis, which can be applied to visualization of electromagnetic system. We have visualized the most fundamental concepts of the electromagnetic vector $\vec{E}=-\vec{\nabla}_{\varphi}$, $\vec{D}={\epsilon}\vec{E}$, $\vec{\nabla}{\times}\vec{A}$, $\vec{B}={\mu}\vec{H}$, $\vec{B}={\mu}_0(\vec{H}+\vec{M})$, which are confirmed with vector calculations and valid graphically with some presentations.

• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.178-191
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• 1993

The electromagnetic filter has been recognized as a technological replacement for the conventional filtration systems of the nuclear power plant coolant. But, as of now there are neither clear understandings of the phenomena occurring in the electromagnetic filter nor the general theoretical analyses. These facts make the application or the electromagnetic filter to the real systems a little risky, and therefore it has not been commercialized although it shows excellent performances in such situations as the plant abnormality, where the conventional filters usually fail. This experimental study of the low power electromagnetic filter aims at the clarification of the general characteristics under varying operational parameters. Since the detailed characteristics may differ from one electromagnetic filter to another, they are considered secondary. The impurities applied are the highly magnetic magnetite (Fe$_3$O$_4$) and the diamagnetic cuprous oxide (Cu$_2$O). The empirical equations are derived from the experimental data by the regressional analyses. They are classified of three types : Efficiencies vs. Time, Efficiencies vs. Load, and Load vs. Time. The characteristics of the electromagnetic filter observed in this experiment agreed well with other related works in many aspects. Especially in this study, some assumptions and discussions including the physical deposition are combined for the explanations of the filter characteristics found in our and other experimental works.

• Geophysics and Geophysical Exploration
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• v.7 no.4
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• pp.251-255
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• 2004

Electric cables such as multi-interphone cables and ribbon cab]os are commonly used for data aquisition in the DC resistivity survey. In general, electromagnetic induction may occur in the electric cables when electric current flows through them. In case of using multi-interphone cables in the DC resistivity survey, electromagnetic induction could take place due to the entangled wires of the multi-interphone cables, when the current flows through them. Then, the electromagnetic induction may cause measured DC resistivity data to be distorted. In this study, a monitoring system with PXI (PCI Extention for Instrumentation) was constructed to examine signal distortion on the DC resistivity data, attributed to the electromagnetic induction. Common electric cables used in the DC resistivity survey were tested to observe the waveforms of the electric voltages. The waveforms measured were compared to examine signal distortion due to the electromagnetic induction. The results may provide information on the resistivity data obtained using different electric cables in the DC resistivity survey. The distortion of waveforms attributed to the electromagnetic induction wat not observed when using ribbon cables for DC resistivity data aquisition, while the distortion were observed when using multi-interphone. Therefore, the ribbon cables provide better quality of data than other cables in the DC resistivity data aquisition.