• Journal of the Korean Vacuum Society
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• v.6 no.1
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• pp.85-90
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• 1997

A new ionized sputtering process was developed to fill small trench or via using additional ionizing mechanism of sputtered particles from 32cm $AlCu_x$(x=0.5%) cathode target with rotating magnet, then drawn toward substrate by small negative DC potential. The radial uniformity in RFI magnetron sputtering was studied by plasma diagnosis and appropriate RFI coil design to improve it. Optical emission intensities of excited species. $Ar^{\circ}, \;Ar^+;Al^+, \;Al^{\circ}$ are measured across the radial direction and showed close correlation with deposit's bottom to top thickness ratios in trenches and vias of submicron opening and 1.5 aspect ratio. After increase of the diameter of RF coil from 29 cm to 32 cm and improved the power leading feedthrough symmetry by removal of asymmetric single turn region, there was an increase of uniformity from 7.5% to 1.5% in bottom to top thickness ratio in 0.6 $\mu\textrm{m}$ vias.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.149-155
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• 2014

In this paper, we study the complex mobile antenna for WPT(Wireless Power Transfer) with NFC(Near Field Communication) of inductive coupling using FPCB which has half thickness compared with the existing coil type antennas. Considering the pattern thickness of loop antenna, the analysis of electromagnetic wave absorber and battery's influence, absorber thickness, the ranges of design parameters are obtained. The proposed antenna has 0.45 mm thickness using single layer 3 oz FPCB and absorber. From measurement, the characteristics of NFC antenna can be satisfied with the specifications of EMVCo. and domestic mobile telecommunication and the transmission efficiency of the proposed WPT antenna is 68.1 % which is competitive with the existing coil type antenna. From the results of this paper, it has been confirmed that the proposed antenna can be used as the WPT and NFC antenna for mobile phone. Key words: Wireless Power Transfer, Near Field Communication, Mobile Phone Antenna, Absorber, FPCB.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.3 s.55
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• pp.33-42
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• 2007

In this study, for research on an improvement of the seismic safety of an EDG system, a small scale EDG system was manufactured. For the isolation system, the Coil Spring-Viscous Damper systems were selected. For the shaking table test, 3 kinds of seismic motions were selected which had different frequency contents. In this study, the isolation effects were different and they depended on the input seismic motion. In the case of an NRC earthquake which had low fiequency contents, the isolation effects of the horizontal direction were 20%. But for the seismic motions which had high fiequency contents, the isolation effects were $50{\sim}70%$. In the case of the vertical direction, poor isolation effects were observed. It was because the design properties and the real properties of the isolation system were a little different.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1018-1024
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• 2011

For the driving of the sinusoidal type permanent magnet synchronous motor with a maximum continuous torque, the 1200 delayed three phase sinusoidal current inputs which matched with the absolute rotor position are needed at the stator coil. Therefore, the detection of a absolute rotor position is required inevitably. And the right angle relationship between stator magnetic field and rotor magnetic field has to be preserved at a stator by this commutation action. The detection of a absolute position for the commutation can be made generally by the output signal analysis of the encoder attached at a motor shaft. The purposes of this study are to design signal processing logic circuits which could detect the absolute position of motor with a modern encoder system and generate the three reference wave for making sinusoidal current input at a stator coil.

• Journal of Sensor Science and Technology
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• v.19 no.6
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• pp.449-455
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• 2010

Implantable middle ear hearing devices(IMEHDs) have being actively studied to overcome the problems of conventional hearing aids. Vibration transducer, an output devices of IMEHDs, is attached on the ossicular chain and transmits mechanical vibration to cochlea. This approach allows us to hear more clear sound because mechanical vibration is effective to transfer high frequency acoustics, but occurs some problems such as fatigue accumulation to ossicular chian and reduction of vibration displacement caused by mass loading effect. Recently, many studies for the round window stimulation are announced, because it does not cause such problems. It have been studied by older transducers designed for attaching on ossicular chain. In this paper, we proposed a new electromagnetic transducer which consists of two magnets, three coils and a vibration membrane. The magnet assembly, magnet coupled in opposite direction, were placed in the center of three coils, and the optimum length of each coil generating maximum vibrational force was calculated by finite element analysis(FEA). The transducer was implemented as the calculated length of each coil, and measured vibration displacement. From the results, it is verified the vibration displacement can be improved by optimizing the length of coils.

• Journal of the Korean Vacuum Society
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• v.7 no.2
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• pp.161-168
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• 1998

Reactive ion etching process for InGaAs/InP using the CH4/H2 high density inductively coupled plasma was investigated. The experimental design method proposed by Taguchi was utilized to cover the whole parameter range while maintaining reasonable number of actual experiments. Results showed that the ICP power mainly affects surface roughness and verticality of the sidewall, bias power does etch rate and verticality, CH4 gas concentraion does the verticality and etch rate, and the distance between the induction coil and specimen mostly affects the surface roughness. It was also observed that the chamber pressure is the dominant parameter for the etch rate and verticality of the sidewall. The optimum condition was ICP power 700W, bias power 150 W, 15% $CH_4$, 7.5 mTorr, and 14 cm distance, resulting in about 3 $\mu\textrm{m}$/hr etch rate with smooth surfaces and vertical mesa sidewalls.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2699-2708
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• 2020

Helical-coil steam generator (HCSG) technology is a major design candidate for small modular reactors due to its compactness and capability to produce superheated steam with high generation efficiency. In this paper, we investigate the feasibility of the passively autonomous power maneuvering by coupling the 3-D transient multi-physics of a soluble-boron-free (SBF) core with a time-dependent HCSG model. The predictor corrector quasi-static method was used to reduce the cost of the transient 3-D neutronic solution. In the numerical system simulations, the feedwater flow rate to the secondary of the HCSGs is adjusted to extract the demanded power from the primary loop. This varies the coolant temperature at the inlet of the SBF core, which governs the passively autonomous power maneuvering due to the strongly negative coolant reactivity feedback. Here, we simulate a 100-50-100 load-follow operation with a 5%/minute power ramping speed to investigate the feasibility of the passively autonomous load-follow in a 450 MW_th SBF PWR. In addition, the passively autonomous frequency control operation is investigated. The various system models are coupled, and they are solved by an in-house Fortran-95 code. The results of this work demonstrate constant steam temperature in the secondary side and limited variation of the primary coolant temperature. Meanwhile, the variations of the core axial shape index and the core power peaking are sufficiently small.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.545-550
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• 2023

A pretensioner is a safety device that protects occupants by pulling the seat belt in the event of a vehicle collision. However, since the pretensioner is driven by a explosive method, it is necessary to replace not only the gas generator but also all connecting parts including the manifold after an accident. Therefore, in this paper, we propose an elastic force-based pretensioner that can be used safely and semi-permanently. After analyzing the operating mechanism of the existing pretensioner from a thermodynamic/dynamic point of view, the spring stiffness that can be deployed within an appropriate operating time was determined by converting the gas explosion energy into elastic energy. In addition, the coil spring shape that satisfies the elastic stiffness was designed in consideration of the vehicle interior installation standard. Finally, the operating performance of the pretensioner driven by elastic force was verified through fabrication.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.650-657
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• 2001

This paper explains the process of designing a shielded encircling remote field eddy current (RFEC) probe to inspect nuclear fuel cladding tubes and investigates resulting signal characteristics. To force electromagnetic energy from exciter coil to penetrate into the tube, exciter coil is shielded outside by laminations of iron insulated electrically from each other. Effects of shielding and the proper operating frequency are studied by the finite element analysis and the location for sensor coil is decided. However, numerically simulated signals using the designed probe do not clearly show the defect indication when the sensor passes a defect and the other indication appeared as the exciter passes the defect is affected by the shape of shielding structure, which demonstrates that the sensor is directly affected by exciter fields. For this reason, the sensor is also shielded outside and this shielding dramatically improves signal characteristics. Numerical modeling with the finally designed probe shows very similar signal characteristics to those of inner diameter RFEC probe. That is, phase signals show almost equal sensitivity to inner diameter and outer diameter defects and the linear relationship between phase signal strength and defect depth is observed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.4
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• pp.331-341
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• 2013

In a solar domestic hot water (SDHW) system, solar energy is collected using collector panels, transferred to a circulating heat transfer fluid (brine), and eventually stored in a thermal storage tank (TST) as hot water. In this study, a computational fluid dynamics (CFD) model was developed to predict the solar thermal energy storage in a hybrid-type TST equipped with a helical jacket heater (mantle heat exchanger) and an immersed spiral coil heater. The helical jacket heater, which is the brine flow path attached to the side wall of a TST, has advantages including simple system design, low brine flow rate, and enhanced thermal stratification. In addition, the spiral coil heater further enhances the thermal performance and thermal stratification of the TST. The developed model was validated by the good agreement between the CFD results and the experimental results performed with the hybrid-type TST in SDHW settings.