• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2166-2172
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• 2007

In this study a low-signal equivalent circuit based on the Double Schottky Barrier model is proposed for ZnO-based varistor. Since pin-lead inductance and stray capacitance are considered in pin-lead type ZnO varistor these inductance and capacitance could be removed from the experimental dielectric data of the varistor. According to the equivalent circuit simulation results the higher the varistor-voltage of varistor sample the capacitance of dielectric layer is larger, and the capacitances of semiconducting layer and depletion layer are smaller, while the parallel resistances of semiconducting layer and depletion layer are more larger values. Spectra of the dielectric loss factor $tan{\delta}$ show 2 peaks in low frequency and high frequency regions respectively. The low-frequency peak is due to the relaxation by deep donors and the high-frequency peak is due to the relaxation by shallow donors. Above results are well consistent with the theoretical mechanism of ZnO varistor.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1418-1420
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• 2003

In this study capacitance and dielectric loss tan${\delta}$were measured with frequency changes for commercial $Z_nO$ varistors with pin-type leads and equivalent circuit simulation was proposed. The leakage inductance in pin leads and the stray caoacitance could be seperated from the dielectric characteristics of $Z_nO$ varistors by the simulation of equivalent circuit. The equivalent circuit model considered semiconduction layer, dielectric layer and depletion layer as the grain boundary structure of varistor is well fitted to the observed data.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.11
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• pp.95-101
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• 2008

We have used diversely the multilayer ceramic oscillator of the SMD(Surface Mounted Device) package technology that connects the crystal with the chip package. Such an oscillator occurs a stray inductance and a parasitic capacitance by the length and inner pattern. And it has been happened an amplitude attenuation and signal loss due to the reflection of power source and noise component. So we don't evaluate the precise performance of the oscillator for these factors. In this paper we have developed the Jig system to evaluate the performance of the oscillator. Through this system, we will expect an advanced performance of the oscillator and redesign an oscillator of the low jitter characteristics and low phase noise.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.4 s.310
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• pp.45-52
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• 2006

In his paper, we have developed the SMD(surface mounted device) type PECL(positive emitter-coupled logic) VCXO of the $5{\times}7mm$ size for gratifying the requested specifications and the multilayer ceramic SMD(surface mounted device) package technology. The VCXO wired with the PECL(positive emitter coupled logic) package take place a stray inductance and a parasitic capacitance by the length and the inner pattern of the VCXO and the amplitude attenuation and signal loss due to the reflection of power source and the noise component. We have developed the Zig system to analyze the precise spectrum and evaluate the performance. The basic operating voltage is the 3.3 V and have the frequency range of 120MHz-180MHz. The Q factor is over 5K and it has the low jitter characteristics of 3.5 ps and low phase noise.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1546-1551
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• 2008

This paper is concerned with the problems of accurate losses segregation in capacitor-run single phase motor. Segregation of losses in single phase induction motor is more complicated than that in three phase induction motor, because of the backward magnetic field component in the motor. Generally there are two methods for losses segregation of single phase induction motor. The one is relatively complicated method based on parameter estimation of single phase induction motor. By the way, the other one is simplified method based on IEEE Standard 114. All of the methods for the experimental determination of single phase induction motor losses are studied in this paper. Since the IEEE Standard is not possible to be applied for all type of single phase induction motors, we modified that method to apply for losses segregation of capacitor-run single phase induction motor as unifying the method based on parameter estimation.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1715-1717
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• 1997

This paper deals with the dead operation characteristics of the earth leakage circuit breaker(ELB) caused by impulse voltages. The surge protective devices for electronic circuit and AC power lines are becoming more widely used. It is possible to give rise to the malfunction of ELB due to the operation of surge protective devices, and the interruption of AC power lines brings about several disadvantages such as low reliability of electronic and informational systems, economical loss, and etc. The dead operation characteristics of the ELB from impulse voltages were measured under the conditions of KS C 4613 and the test circuit with a varistor. As a result, the peak current value of the zero-phase sequence circuit of the ELB is increased as the surge voltage and stray capacitance increase. All of the ELBs used in this work were satisfied with the lightning impulse dead operation test condition defined in KS C 4613. However one specimen only did not cause dead operation in the condition of the test circuit with a varistor. There is high possibility that a large portion of the ELBs connected with the AC power lines having the surge protective devices bring about the dead operation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.587-590
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• 2003

The first attention in designing a transformer for low temperature rise should be to reduce losses. Leakage inductance and temperature rise are two of the more impotent problems facing the magnetic core technology of today's high frequency transformers. Excessive leakage inductance increases the stress on the switching transistors and limits the duty-cycle, and excessive temperature rise can lead the design limitation of high frequency transformer with high current. The flat transformer technology provides a very good solution to the problems of leakage inductance and thermal management for high frequency power. The critical magnetic components and windings are optimized and packaged within a completely assembled module. The turns ratio in a flat transformer is determined as the product of the number of elements or modules times the number of primary turns. The leakage inductance increase proportionately to the number of elements, but since it is reduced as the square of the turns, the net reduction can be very significant. The flat transformer modules use cores which have no gap. This eliminates fringing fluxes and stray flux outside of the core. The secondary windings are formed of flat metal and are bonded to the inside surface of the core. The secondary winding thus surrounds the primary winding, so nearly all of the flux is captured.

• Korean Journal of Artificial Intelligence
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• v.9 no.1
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• pp.29-35
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• 2021

In this paper, we analyzed the factors of adoption and implemented a predictive model to activate the adoption of animals. Recently, animal shelters are saturated due to the abandonment and loss of companion animals. To address this, we need to find a way to encourage adoption. In this paper, a study was conducted using two data from an open data portal provided by Austin, Texas. First, a correlation analysis was conducted to identify the attributes that affect the result value, and it was found that Animal Type Intake, Intake Type, and Age upon Outcome influence the Outcome Type with correlation coefficients of 0.4, 0.26, and -0.2, respectively. For these attributes, the analysis was conducted using Multiclass Logistic Regression. As a result, dogs had a higher probability of Adoption than cats, and animals subjected to euthanasia were more likely to adopt. In the case of Public Assist and Stray, it was found that the Missing rate was high. Also, the length of stay for cats increased to 12.5 years of age, while dogs generally adopted smoothly at all ages. These results showed an overall accuracy of 62.7% and an average accuracy of 91.7%, showing a fairly reliable result. Therefore, it seems that it can be used to develop a plan to promote the adoption of animals according to various factors. Also, it can be expanded to various services by interlocking with the webserver.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.117-122
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• 2012

The interstellar dust grains are formed and supplied to interstellar space from asymptotic giant branch (AGB) stars or supernova remnants, and become constituents of the star- and planet-formation processes that lead to the next generation of stars. Both a qualitative, and a compositional study of this cycle are essential to understanding the origin of the pre-solar grains, the missing sources of the interstellar material, and the chemical evolution of our Galaxy. The AKARI/MIR all-sky survey was performed with two mid-infrared photometric bands centered at 9 and $18{\mu}m$. These data have advantages in detecting carbonaceous and silicate circumstellar dust of AGB stars, and the interstellar polycyclic aromatic hydrocarbons separately from large grains of amorphous silicate. By using the AKARI/MIR All-Sky point source catalogue, we surveyed C-rich and O-rich AGB stars in our Galaxy, which are the dominant suppliers of carbonaceous and silicate grains, respectively. The C-rich stars are uniformly distributed across the Galactic disk, whereas O-rich stars are concentrated toward the Galactic center, following the metallicity gradient of the interstellar medium, and are presumably affected by the environment of their birth place. We will compare the distributions of the dust suppliers with the distributions of the interstellar grains themselves by using the AKARI/MIR All-Sky diffuse maps. To enable discussions on the faint diffuse interstellar radiation, we are developing an accurate AKARI/MIR All-Sky diffuse map by correcting artifacts such as the ionising radiation effects, scattered light from the moon, and stray light from bright sources.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.709-718
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• 2021

In this paper, it can be seen that the number of abandoned dogs increases every year through the statistics on the occurrence of abandoned animals. With the goal of reducing the number of stray dogs, a smart pet dog shoulder strap is implemented based on a real-time location tracking system using the ESP32 module and GPS sensor. It is an ESP32 module with a built-in Bluetooth module. It is input to the MCU using various sensors, and finally outputs to a smart-phone application, and communicates through the built-in blue-tooth module. In addition, it uses Neopixels to compensate the weaknesses at night through LED light emission, and automatically sets the warning distance to design a music playback system through the LED flashing effect and MP3 module. In addition, a smart pet dog shoulder strap was designed to help pet dog health care by measuring the moving distance according to the amount of activity through the gyro sensor.