• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.354-359
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• 2020

The high vacuum hermetic sealing technique ensures excellent performance of MEMS resonators. For the high vacuum hermetic sealing, the customization of anodic bonding equipment was conducted for the glass/Si/glass triple-stack anodic bonding process. Figure 1 presents the schematic of the MEMS resonator with triple-stack high-vacuum anodic bonding. The anodic bonding process for vacuum sealing was performed with the chamber pressure lower than 5 × 10^-6 mbar, the piston pressure of 5 kN, and the applied voltage was 1 kV. The process temperature during anodic bonding was 400 ℃. To maintain the vacuum condition of the glass cavity, a getter material, such as a titanium thin film, was deposited. The getter materials was active at the 400 ℃ during the anodic bonding process. To read out the electrical signals from the Si resonator, a vertical feed-through was applied by using through glass via (TGV) which is formed by sandblasting technique of cap glass wafer. The aluminum electrodes was conformally deposited on the via-hole structure of cap glass. The TGV process provides reliable electrical interconnection between Si resonator and aluminum electrodes on the cap glass without leakage or electrical disconnection through the TGV. The fabricated MEMS resonator with proposed vacuum packaging using three-layer anodic bonding process has resonance frequency and quality factor of about 16 kHz and more than 40,000, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1892-1897
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• 2012

Modern electronic circuits are of importance for the function of communication, traffic systems and security systems. An intentional threat to these systems could be of big casualties and economic disasters. This study has examined susceptibility of electronic circuits inside the cavity by HPEM(High Power Electromagnetics). The UWB measurements were done at an anechoic chamber using a RADAN voltage source, which can generate a transient impulse of about 200 kV. The HPEM wave penetrated inside the metal case appeared to the long damped ringwave of pulse length compared with the incident wave. In addition, the resonant frequency generated inside the metal case occurred primarily in the range of 1~3 GHz. The frequency band of 1~3 GHz was influenced on the electronic circuit, which was confirmed by an external antenna and an internal absorber. The electronic circuit was influenced by HPEM infiltrated into the cavity at the 86 kV/m out of the metal cases. Also in case of an absorber the susceptibility of an electronic circuit was smallest among other cases(aperture, antenna). It is considered that absorber has a function absorbing electromagnetic wave infiltrated into the cavity and simultaneously limiting resonance by varying a boundary condition inside the cavity. Based on the results, electronic equipment systems could be applied to protection that has suited system requirements.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.7
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• pp.571-574
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• 2010

Surface recombination loss should be reduced for high efficiency of solar cells. To reduce this loss, the BSF (back surface field) is used. The BSF on the back of the p-type wafer forms a p+layer, which prevents the activity of electrons of the p-area for the rear recombination. As a result, the leakage current is reduced and the rear-contact has a good Ohmic contact. Therefore, the open-circuit-voltage (Voc) and fill factor (FF) of solar cells are increased. This paper investigates the formation of the rear contact process by comparing aluminum-paste (Al-paste) with pure aluminum-metal(99.9%). Under the vacuum evaporation process, pure aluminum-metal(99.9%) provides high conductivity and low contact resistance of $4.2\;m{\Omega}cm$, but It is difficult to apply the standard industrial process to it because high vacuum is needed, and it's more expensive than the commercial equipment. On the other hand, using the Al-paste process by screen printing is simple for the formation of metal contact, and it is possible to produce the standard industrial process. However, Al-paste used in screen printing is lower than the conductivity of pure aluminum-metal(99.9) because of its mass glass frit. In this study, contact resistances were measured by a 4-point probe. The contact resistance of pure aluminum-metal was $4.2\;m{\Omega}cm$ and that of Al-paste was $35.69\;m{\Omega}cm$. Then the rear contact was analyzed by scanning electron microscope (SEM).

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.155-166
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• 2016

It is important to configure capacitance(C) of the capacitor and the induction coefficient(L) of the work coil on the resonant circuit design stage in order to induce heating on the object by a precise and constant frequency components in the electromagnetic induction heating equipment. Work coil conducts a direct induction heating according to heating point and area of the object which has a fixed heat factor so that work coil is designed to has fixed value. On the other hands, Capacitor should be designed to be changed in order to be the higher the utilization of the entire equipment. It is extracted the samples by variation of single electrode capacity from the selection stage of raw materials for capacity to the stage of process design for output of the high frequency LC resonance of 700kHz on 1000 VAC maximum voltage and current to $200I_{MAX}$. It is suggested fundamental experiment results in order to prove relation for the optimal design of HF-LC resonance conduction-cooled capacitor based on the response of frequency characteristics and results of output parameters according to variation of the capacitance size.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.123-130
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• 2016

High-frequency induction heating equipment can heat the metal by applying a High-Frequency power to the resonant circuit. The resonance circuit is composed of the work coil and the conduction-cooled power capacitor, it influences the performance of the heat treatment equipment according to the characteristics of the capacitor. However, dependence on conduction-cooled power capacitor's import is high due to lack of core technology research and development. Minimizing the generation of internal heat transmitted inside during LC resonance, reduce the reactive power loss, there is a need for a capacitor within the voltage characteristic outstanding. To implement localization it is vital that prior study of the analysis on the frequency response characteristic for the finished capacitor advanced manufacturer be implemented. Studying the interpolation method to read the value at any point of the characteristic curve for a given log-log scale was applied to the analysis tool of the capacitor by my proposed algorithm. The simulation for reproducing frequency response curves was attempted by assuming a capacitor in a simplified series equivalent RC circuit to obtain the equivalent series resistance value. It was confirmed that the reproduction rate was the result value above 83% as compared to the simulation of the properties and characteristics on the actual reactive power for Peak value, and that the algorithm can be applicable when analyzing and predicting the characteristic curves of a simpled model capacitor.

• Applied Microscopy
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• v.36 no.1
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• pp.7-16
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• 2006

A new remote access system for a 1.3 MV high voltage electron microscope has been developed. Almost all essential functions for HVEM operation, huck as stage control, specimen tilting, TV camera selection and image recording, are successfully embedded into this prototype of the remote system. Particularly, this system permits perfect and precise operation of the goniometer and also controls the high resolution digital camera via simple Web browsers. Transmission of control signals and communication with the microscope is accomplished via the global ring network for advanced applications development (GLORIAD). This fact makes it possible to realize virtual laboratory to carry out practical national and international HVEM collaboration by using the present system

• The Journal of Korean Society for Radiation Therapy
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• v.31 no.1
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• pp.17-24
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• 2019

Purpose: The present study aims to assess the level of coherency and the accuracy of Point dose of the Isocenter of VERO, a linear accelerator developed for the purpose of the Stereotactic Body Radiation Therapy(SBRT). Materials and Method: The study was conducted randomly with 10 treatment plans among SBRT patients in Kyungpook National University Chilgok Hospital, using VERO, a linear accelerator between June and December, 2018. In order to assess the equipment's power stability level, we measured the output constancy by using PTW-LinaCheck, an output detector. We also attempted to measure the level of accuracy of the equipment's Laser, kV(Kilo Voltage) imaging System, and MV(Mega Voltage) Beam by using Tofu Phantom(BrainLab, Germany) to assess the accuracy level of geometrical Isocenter. We conducted a comparative analysis to assess the accuracy level of the dose by using an acrylic Phantom($30{\times}30{\times}20cm$), a calibrated ion chamber CC-01(IBA Dosimetry), and an Electrometer(IBA, Dosimetry). Results: The output uniformity of VERO was calculated to be 0.66 %. As for geometrical Isocenter accuracy, we analyzed the error values of ball Isocenter of inner Phantom, and the results showed a maximum of 0.4 mm, a minimum of 0.0 mm, and an average of 0.28 mm on X-axis, and a maximum of -0.4 mm, a minimum of 0.0 mm, and an average of -0.24 mm on Y-axis. A comparison and evaluation of the treatment plan dose with the actual measured dose resulted in a maximum of 0.97 % and a minimum of 0.08 %. Conclusion: The equipment's average output dose was calculated to be 0.66 %, meeting the ${\pm}3%$ tolerance, which was considered as a much uniform fashion. As for the accuracy assessment of the geometric Isocenter, the results met the recommended criteria of ${\pm}1mm$ tolerance, affirming a high level of reproducibility of the patient's posture. The difference between the treatment plan dose and the actual measurement dose was calculated to be 0.52 % on average, significantly less than the 3 % tolerance, confirming that it obtained predicted does. The current study suggested that VERO equipment is suitable for SBRT, and would result in notable therapeutic effect.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1632-1638
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• 2011

Electric cables are one of the most important components in a nuclear power plant since they provide the power needed to operate electrical equipment. Despite their importance, cables typically receive little attention since they are considered passive, long-lived components that have been very reliable over the years when subjected to the environmental conditions for which they were designed. The operating experience reveals that a defect of the insulator or poor construction causes the initial failure of cable. However, the number of cable failures increase with plant aging, and these cable failures are occurring within the plants' 40-year licensed period. These cable failures have resulted in plant transients, shutdown, loss of safety functions or redundancy, entries into limiting conditions for operation, and challenges for plant operators. Therefore, diagnosis of MV cable installed in NPPs has become one of the most urgent issues in recent years. In accordance with PSR, condition maintenance for cables is also continuously required. Recently, HFPD tests have been widely performed to diagnose cable in the transmission and distribution cable system. However, on-line HFPD wasn't used in the NPPs because of the danger of plant shutdown, measurement sensitivity and application problems, etc. In this paper, HFPD measurement with portable device was performed to evaluate the integrity of the 4.16kV & 13.8kV cable lines. The test results show that HFPD is highly attractive to the diagnosis of MV cables in NPP by high detection sensitivity on-site.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.1
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• pp.136-142
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• 2005

In this paper, we wrote about the basic experimentation of Optical CT's temperature characteristic to measure high-current in a super-high-voltage electric power equipment which is using Faraday effect. We used the 1310[nm] Laser Diode as the light source and PIN Photodiode as receiver. For the transmission line of light, we used 30[m] single mode fiber which could maintain the state of polarization in the optical fiber. For the experiment, the temperature transformation device make by aluminium. the The range of current was from 400[A] and 1300[A] and the range of temperature was from $-40[^{\circ}C]\;to\;50[^{\circ}C]$. In a same experimental condition, magnitude increased input current increase follow by increasing proportion of input current.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.96-100
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• 2009

With the improvement of industrial society, the high quality electrical energy, simplification of operation and maintenance, ensuring reliability and safety are being required. This paper compares breakdown characteristics in $SF_6$ gas with $N_2/O_2$ Mixture gas($N_2:O_2=100$ : 0, 79 : 21, 60 : 40, 40 : 60) as using widely in High Voltage insulation equipment with the characteristics in different media which are focused on environmentally friendly gases. As an append result of research the results are fundamental data for electric insulation design of Distribution Power Facilities which will be studied and developed in the future. And we could make an environment friendly gas insulation material with mataining dielectric strength by $N_2/O_2$ Mixture gas which generates a lower lever of the global warming effect.