• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.40-42
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• 1999

High-speed brushless permanent magnet machines are good for compressor and aerospace applications, etc, since they are conductive to high efficiency, high power density, small size and low weight. This paper describes a diametrically magnetized PM motor with the rating of 4.3kW and 50000 rpm fur high-speed drive applications. To bear strong stress from high speed, rotor was designed cylindrical structure, was magnetized diametrically permanent magnet. The performance characteristic of motor was evaluated by means of FEA(Finite Element Analysis), no-load test And then, in order to find back-EMF constant, used FEA, search coil.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.295-300
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• 2001

A variety of high voltage DC power supplies employing the high frequency inverter are difficult to achieve soft switching considering a quick response and no overshoot response under the wide load variation ranges which are used in medical-use x-ray high voltage generator from 20kV to 150kV in the output voltage and from 0.5mA to 1250mA, respectively. The authors develops soft switching high voltage DC power supply designed for x-ray power generator applications, which uses series resonant inverter circuit topology with a multistage voltage multiplier instead of a conventional high voltage diode rectifier connected to the second-side of a high-voltage transformer with a large turn ratio. A constant on-time dual mode frequency control scheme operating under a principle of zero-current soft switching commutation is described. Introducing the multistage voltage multiplier, the secondary transformer turn-numbers and stray capacitance of high-voltage transformer is effective to be greatly reduced. It is proved that the proposed high-voltage converter topology with dual mode frequency modulation mode control scheme is able to be the transient response and steady-state performance in high-voltage x-ray tube load. The effectiveness of this high voltage converter is evaluated and discussed on the basis of simulation analysis and observed data in experiment.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.388-388
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• 2012

In this letter, We have investigated cell characteristics of the alloy FePt-NDs charge trapping memory capacitors with high-k $Al_2O_3$ dielectrics as a blocking oxide. The capacitance versus voltage (C-V) curves obtained from a representative MOS capacitor embedded with FePt-NDs synthesized by the post deposition annealing (PDA) treatment process exhibit the window of flat-band voltage shift, which indicates the presence of charge storages in the FePt-NDs. It is shown that NDs memory with high-k $Al_2O_3$ as a blocking oxide has performance in large memory window and low leakage current when the diameter of ND is below 2 nm. Moreover, high-k $Al_2O_3$ as a blocking oxide increases the electric field across the tunnel oxide, while reducing the electric field across the blocking layer. From this result, this device can achieve lower P/E voltage and lower leakage current. As a result, a FePt-NDs device with high-k $Al_2O_3$ as a blocking oxide obtained a~7V reduction in the programming voltages with 7.8 V memory.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.374-376
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• 2018

In this study, we developed a mobile home robot using a face recognition method using a camera attached to a raspberry pie. It receives the real time image through the camera attached to the raspberry pie, recognizes the face of the person, and distinguishes the operation of the smart cool air temperature device according to the result. It is expected that the robot will be able to increase the energy utilization efficiency by allowing the robot to operate in cold and hot winds only where there is no human being, instead of operating the hot and cold air conditioner.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.380-382
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• 2018

In this study, we developed software for portable lifter using Android application for stability of portable lifter which can load freight easily. Arduino Uno R3 boards were used for this purpose. The existing portable lifts were disassembled to mount the Arduino Uno R3 board and circuit, and to send and receive signals via Bluetooth communication. This study can be expected to contribute greatly to the safety work of logistics activities.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.371-373
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• 2018

The function of the direction indicator is essential for the safety of bicycle trips and commuters. In this study, the direction indicator function was developed on the prefabricated bicycle using the Arduino. With the simple function of the Arduino, you can attach a switch to the handle to turn the direction indicator on and off. Since it is a simple function, it is judged that it is suitable for the maker activity that can make it by DIY by oneself having a bicycle. In this paper, we have opened the possibility of attaching a lot of services to bicycles through the proposed functions.

• Nutritional Sciences
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• v.7 no.1
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• pp.8-16
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• 2004

The purpose of this study was to investigate the gene profiles that were up- or down-regulated in the livers of high-fat diet-induced obese mice and $db_-/db_-$ mice with deficient leptin receptor. C57/BL6 normal mice and $db_-/db_-$ mice, respectively, were divided into two groups and fed a standard or high-fat diet for four weeks. Liver weight was unchanged in the normal mice but the high-fat diet led to a 10% weight increase in the $db_-/db_-$mice. Adipose tissue mass increased by about 88% in the normal mice that were fed a high-fat diet and by about 17% in the $db_-/db_-$mice on the high-fat diet. In terms of serum lipids, total cholesterol significantly increased in mice on the high-fat diet. Microarray analysis was carried out using total RNA isolated from the livers of standard or high-fat diet-fed mice of the normal and $db_-/db_-$ strains. The change of gene expression was confirmed by RT-PCR. About 1.6% and 6.8% of total genes, respectively, showed different expression patterns in the normal mice fed the high-fat diet and $db_-/db_-$ mice. As a result of microarray, many genes involved in metabolism and signal pathways were shown to have different expression patterns. Expression of Mgst3 gene increased in the livers of normal and $db_-/db_-$ mice that were fed a high-fat diet. Wnt7b and Ptk9l were down-regulated in the livers of the normal mice and $db_-/db_-$ mice that were fed a high-fat diet. In conclusion, a high-fat diet induced obesity and affected gene expression involved in metabolism and signal pathway.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.4
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• pp.180-184
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• 2001

The high operation frequency mainly reduces transformer volume in the power supply. A high frequency and high voltage pulse transformer is designed, fabricated, and tested. Switching frequency of the transformer is 100 kHz. Input and output voltages of the transformer are 250 V and 4 kV, respectively. Normal operation power of the transformer is 3 kW. Maximum volume of the transformer is 400 $cm^3$. The power density is thus 7.5 W/$cm^3$. The transformer will be installed in a metal box that has nominal operation temperature of 85 degree centigrade. The transformer and other high voltage components in the box will be molded with Silicon RTV(Room Temperature Vulcaniza) that has a very low thermal conductivity. Procedure of design and test results are discussed. Analytical as well as experimental results of varous paramters such as transformer loss, leakage inductance, distributed capacitance are also discussed. In addition, thermal analysis results from ANSYS code for three different operation conditions are discussed.

• Journal of the Korean Society of School Health
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• v.29 no.3
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• pp.132-139
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• 2016

Purpose: In this study, we analyzed the correlation between high-caffeine energy drink intake and mental health in high school students. Methods: Analyses were conducted using the data of 27,097 responses from the 2015 Korea Youth Risk Behavior Web-based Survey of general high school students. Data were analyzed by logistic regression based on a complex sample design. Results: High-caffeine energy drink intake was positively correlated with the rates of smoking, alcohol consumption, violence, depression, and suicidal thoughts and negatively correlated with the sense of happiness. Conclusion: High-caffeine energy drink intake has a significant impact on the mental health of high school students. Therefore, in-depth research and policies on high-caffeine energy drink intake and the mental health of young individuals are required.

• Journal of Power Electronics
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• v.7 no.2
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• pp.118-123
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• 2007

This paper presents a new ZCS-PWM high frequency inverter. Zero current switching operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. Dual duty cycle control scheme is used to provide a wide range of high frequency AC output power regulation that is important in many high frequency inverter applications. It found that a complete soft switching operation can be achieved even for low power setting ranges by introducing high-frequency dual duty cycle control scheme. The proposed high frequency inverter is more suitable for consumer induction heating(IH) applications. The operation and control principle of the proposed high frequency inverter are described and verified through simulated results.