• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.71-78
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• 2010

The objective of this research is to investigate the influence of material characteristic and design on to the electromagnetic interference (EMI) shielding characteristics. Basalt glass fiber reinforced composite specimens with stainless fiber conductive filler were manufactured to perform the electromagnetic interference shielding effectiveness(SE) experiments. In order to reflection and absorb the specimen in electromagnetic fields, flanged coaxial transmission line sample holder was fabricated according to ASTM D 4935-89. Electromagnetic shielding effectiveness(EMSE) was measured quantitatively to examine the electromagnetic shielding characteristics of designed specimens. The result of EMI shielding experiments showed that maximum EMSE value of sandwich type specimens with GSG(basalt glass fiber/stainless fiber/basalt glass fiber) and SGS(stainless fiber/basalt glass fiber/stainless fiber) were 65dB and 80dB at a frequency of 1,500MHz, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.121-128
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• 2005

The research on electromagnetic shielding has been advanced for military applications as well as for commercial products. Utilizing the reflective properties and absorptive properties of shielding material, the replied signal measured at the rear surface or at the signal source can be minimized. The shielding effect was obtained from materials having special absorptive properties and structural characteristics such as stacking sequence. Recently researchers studied the electromagnetic properties of nano size particles. In this research {glass fiber}/{epoxy}/{nano particle} composites(GFR-Nano composites) was fabricated using various nano particles, and their properties in electromagnetic shielding were compared. For the visual observation of the nano composite materials, SEM(Scanning Electron Microscope) and TEM(Transmission Electron Microscope) were used. For the measurement of electromagnetic shielding, HP8719ES S-parameter Vector Network Analyser System was used on the frequency range of 8 GHz${\~}$12GHz. Among the nano particles, carbon black and Multi-Walled Carbon Nano-Tube (MWCNT) revealed outstanding electromagnetic shielding. Although silver nano particles (flake and powder) were expected to have effective electromagnetic shielding due to their excellent electric conductivities, test results showed little shielding characteristics.

• Coupled systems mechanics
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• v.1 no.1
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• pp.39-57
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• 2012

This study intends to explore dynamic interaction behaviors between actively controlled maglev vehicle and guideway girders by considering the nonlinear forms of electromagnetic force and current exactly. For this, governing equations for the maglev vehicle with ten degrees of freedom are derived by considering the nonlinear equation of electromagnetic force, surface irregularity, and the deflection of the guideway girder. Next, equations of motion of the guideway girder, based on the mode superposition method, are obtained by applying the UTM-01 control algorithm for electromagnetic suspension to make the maglev vehicle system stable. Finally, the numerical studies under various conditions are carried out to investigate the dynamic characteristics of the maglev system based on consideration of the linear and nonlinear electromagnetic forces. From numerical simulation, it is observed that the dynamic responses between nonlinear and linear analysis make little difference in the stable region. But unstable responses in nonlinear analysis under poor conditions can sometimes be obtained because the nominal air-gap is too small to control the maglev vehicle stably. However, it is demonstrated that this unstable phenomenon can be removed by making the nominal air-gap related to electromagnetic force larger. Consequently it is judged that the nonlinear analysis method considering the nonlinear equations of electromagnetic force and current can provide more realistic solutions than the linear analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.4
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• pp.329-337
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• 2007

This paper deals with electromagnetic tests of the GPS receiver system that should be developed to satisfy emission and susceptibility requirements for a satellite launch vehicle. Performance of the GPS receiver system against electromagnetic environment that is improved through several tests satisfies all requirements about electromagnetic tests. The outline of the electromagnetic tests and emission test results of CE102, CE106 and RE102 on MIL-STD-461E are described in Part I.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.161-169
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• 2008

This paper introduces test configuration and operation method for the GPS receiver system under electromagnetic test of KSLV-I upper-stage as a system qualification level and describes performance analysis of the test results. The GPS receiver system has clearly passed the electromagnetic test specifications of component level which is based on MIL-STD-461E through several design changes. Under electromagnetic test as a system qualification level, the GPS receiver system normally operates in spite of electromagnetic interferences with other systems. Performance of the GPS receiver system is also, not degraded on the condition of electromagnetic field incidence and electrostatic discharge. The KSLV-I GPS receiver system, as a result, is verified on the electromagnetic condition of the KSLV-I upper-stage.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1429-1435
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• 2021

The temperature distribution of an electromagnetic pump was analyzed with a flow rate of 1380 L/min and a pressure of 4 bar designed for the sodium thermo-hydraulic test in the Sodium Test Loop for Safety Simulation and Assessment-Phase 1 (STELLA-1). The electromagnetic pump was used for the circulation of the liquid sodium coolant in the Intermediate Heat Transport System (IHTS) of the Prototype Gen-IV Sodium-cooled Fast Reactor (PGSFR) with an electric power of 150 MWe. The temperature distribution of the components of the electromagnetic pump was numerically analyzed to prevent functional degradation in the high temperature environment during pump operation. The heat transfer was numerically calculated using ANSYS Fluent for prediction of the temperature distribution in the excited coils, the electromagnet core, and the liquid sodium flow channel of the electromagnetic pump. The temperature distribution of operating electromagnetic pump was compared with cooling of natural and forced air circulation. The temperature in the coil, the core and the flow gap in the two conditions, natural circulation and forced circulation, were compared. The electromagnetic pump with cooling of forced circulation had better efficiency than natural circulation even considering consumption of the input power for the air blower. Accordingly, this study judged that forced cooling is good for both maintenance and efficiency of the electromagnetic pump.

• Journal of the Korea Society of Computer and Information
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• v.25 no.10
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• pp.231-240
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• 2020

Countries around the world have already taken direct and indirect measures to warn of the harmful effects of mobile phone electromagnetic waves. On the other hand, in the Republic of Korea the installation of Wi-Fi has been expandedwithout restrictions by location, and there is a widespread atmosphere of protesting human rights violations even if young students cannot use mobile phones, ignoring problems caused by the use of mobile phones. Human brain cells are increasingly exposed to electromagnetic waves of mobile phones as the penetration rate of smartphones grows.In order to solve the long-lasting question of whether electromagnetic waves from mobile phones will harm the human body, many studies are being conducted in various countries around the world, andthe recently published findingshave warned of the potential for harm. The labeling of electromagnetic waves alone is not sufficient to raise awareness about the dangers of electromagnetic waves. It is necessary that the Republic of Korea organize and operate a national electromagnetic wave research center in line with its status as an IT powerhouse, along with the revision of the Radio Wave Act, which directly warns the public about the hazards of mobile phone electromagnetic waves and can directly impose obligations on the mobile phone industry.

• Journal of Magnetics
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• v.21 no.2
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• pp.215-221
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• 2016

We conducted a phased electromagnetic forming process analysis (EFPA) over time through a coupling of electromagnetic analysis and structural analysis. The analysis is conducted through a direct linkage between electromagnetic analysis and structural analysis. The analysis process is repeated until the electric current is completely discharged by a formed coil. We calculate the forming force that affects the workpiece using MAXWELL, a commercial electromagnetic finite element analysis program. Then, we simulate plastic behavior by using the calculated forming force data as the forming force input to ANSYS, a commercial structure finite element analysis program. We calculate the forming force data by using the model shape in MAXWELL, a commercial electromagnetic finite element analysis program. We repeat the process until the current is fully discharged by the formed coil. Our results can be used to reduce the error in data transformation with a reduced number of data transformations, because the proposed approach directly links the electromagnetic analysis and the structural analysis after removing the step of the numerical analysis of a graph describing the forming force, unlike the existing electromagnetic forming process. Second, it is possible to simulate a more realistic forming force by keeping a certain distance between nodes using the re-mesh function during the repeated analysis until the current is completely discharged by the formed coil, based on the MAXWELL results. We compare and review the results of the EFPA using the peak value of the forming force that acts on the workpiece (which is the existing analysis method), and the proposed phased EFPA over time approach.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.9
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• pp.559-564
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• 2016

This study examined the malfunction mode of the HCMOS IC under narrow-band high-power electromagnetic wave. Magnetron is used to a narrow-band electromagnetic source. MFR (malfunction failure rate) was measured to investigate the HCMOS IC. In addition, we measured the resistance between specific pins of ICs, which are exposed and not exposed to the electromagnetic wave, respectively. As a test result of measurement, malfunction mode is shown in three steps. Flicker mode causing a flicker in LED connected to output pin of IC is dominant in more than 7.96 kV/m electric field. Self-reset mode causing a voltage drop to the input and output of IC during electromagnetic wave radiation is dominant in more than 9.1 kV/m electric field. Power-reset mode making a IC remained malfunction after electromagnetic radiation is dominant in more than 20.89 kV/m. As a measurement result of pin-to-pin resistance of IC, the differences between IC exposed to electromagnetic wave and normal IC were minor. However, the five in two hundred IC show a relatively low resistance. This is considered to be the result of the breakdown of pn junction when latch-up in CMOS occurred. Based on the results, the susceptibility of HCMOS IC can be applied to a basic database to IC protection and impact analysis of narrow-band high-power electromagnetic waves.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.1
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• pp.12-22
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• 2019

This paper presents a method to perform a more efficient electromagnetic wave analysis inside a large building by external electromagnetic waves. Topological analysis and the PWB method are introduced for electromagnetic wave analysis. In addition, a Performance-Enhanced PWB method, which complements the performance of the PWB method is proposed. A large virtual structure was selected and an analysis environment was set up to perform the electromagnetic wave analysis inside a large building from external electromagnetic waves. A commercially available software, Wireless Insite, was used to verify the accuracy of the the Performance- Enhanced PWB method. As a result of comparing the two results in terms of accuracy, time, and memory, We conclude that the Performance-Enhanced PWB method proposed in this paper is a more efficient method in a large bulding.