• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.370-373
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• 2003

Superluminescent diodes(SLDs) are the optimum light sources for application in optical measurement systems such as fiber gyroscopes, optical time domain reflectometers, and to short and medium distance optical communication systems. The broadband characteristics of SLDs reduce Rayleigh backscattering noise, polarization noise, and the bias offset due to the nonlinear Kerr effect in fiber gyro systems. In this paper, in order to suppress lasing oscillation, we introduced a laterally tilted SCH(Separate Confinement Heterostructure)-SLD with a window region. An output power of 11mW has been achieved at 200mA injection current at 25$^{\circ}C$. At 120mA, parallel and perpendicular to the junction were 31$^{\circ}$${\times}$38$^{\circ}$.

• Proceedings of the KIPE Conference
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• 전력전자학회 2001년도 추계학술대회 논문집
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• pp.139-143
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• 2001

Recently, the interest on power quality has been hot issue. The equipments cause voltage disturbance and has become more sensitive to the voltage disturbance. This paper deals with 5-Level H-Bridge Line-Inter active Dynamic Voltage Restorer(LIDVR) system. The LIDVR has following advantages in comparison with the DVR with series injection transformer It has the power factor near to unity under normal source voltage, can compensate the harmonic current of the load and the instant interruption, and has the fast response. First, the construction, the operation mode and algebraic modeling of LIDVR are reviewed. And then a voltage controller is proposed to get sinusoidal load voltage with constant amplitude. To find PWM method suitable for H-Bridge converter, two PWM methods are compared and analyzed. Finally, simulation results verify the proposed 5-level H-Bridge LIDVR system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.82-85
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• 2008

Polyimide is widely used as a high-temperature insulating material. Space charge distributions in polyimide (PI) films strongly depend upon electric field, temperature, water content and so on. We observed space charge distributions in PI films with various water contents. When a dc field was applied to as-received PI films or water-treated PI films, positive and negative homo space charges were observed near the respective electrodes at 333 K. In dried PI films, the homo space charges were much reduced, and positive and negative hetero space charges in the bulk were clearly observed. The space charge amounts in water-treated PI films were smaller than in as-received ones, while the current density in water-treated PI film was larger than that in as-received one by two or more orders of magnitude. These suggest not only that the charge injection from the electrode is enhanced by absorbed water but also that absorbed water makes carriers mobile. The decay of space charge was also faster in water-treated PI than in as-received or dried one. This also supports the enhancement of apparent mobilities of carriers in PI by absorbed water.

• Proceedings of the KIEE Conference
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2152_2153
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• 2009

In this study, the dynamic characteristic of a contact wire and pantograph suppling electrical power to high-speed trains are investigated from an electrical response point of view. To analysis power line disturbance by induced contact loss phenomenon for high speed operation, a hardware Simulator which considered contact loss between contact wire and the pantograph as well as contact wire deviation is developed. It is confirmed that a contact wire and pantograph model are necessary for studying the dynamic behavior of the pantograph system. One of the most important needs accompanied by increasing the speed of high-speed train is reduced that an arc phenomenon by loss of contact brings out EMI. In case of a high-speed train using electrical power, as comparison with diesel rolling stock, PLD(Power Line Disturbance) such as harmonic, transient voltage and current, EMI, dummy signal injection etc usually occurs. Throughout experiment, it is verified that an arc phenomenon is brought out for simulator operation and consequently conducted noise is flowed in electric circuit by power line disturbance.

• The Transactions of the Korean Institute of Electrical Engineers P
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• 제59권2호
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• pp.206-211
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• 2010

Since high-speed train is a dynamic load in which electric power is externally supplied, contact loss between the catenary and pantograph occurs. This phenomena including vibrations generates frequently irregular arcs, which, in turn causes EMI. Thus it is very important to develop the approach to reduce arc phenomenon by contact loss, as speed of electric railway vehicle increases. In case of an electric railway vehicle using electrical power, compared with diesel rolling stock, Power Line Disturbance(PLD) such as harmonics, transient voltage and current, Electromagnetic Interference(EMI), and dummy signal injection etc usually occur. In this study, the dynamic characteristics of a contact wire and a pantograph suppling electrical power to high-speed train are investigated with an electrical response point. To implement power line disturbance induced by contact loss phenomenon for high speed train operation, a hardware simulator which considers contact loss between contact wire and pantograph as well as contact wire deviation is developed. It is confirmed by the experiments that contact loss effect is largely dependent on voltage conditions when the contact loss occurs. Also, a passive filter is designed to reduce power disturbance and the designed system is verified by experiment.

• The Transactions of the Korean Institute of Electrical Engineers P
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• 제58권4호
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• pp.427-431
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• 2009

In this study, the dynamic characteristic of a contact wire and pantograph suppling electrical power to high-speed trains are investigated from an electrical response point of view. To analysis power line disturbance by induced contact loss phenomenon for high speed operation, a hardware Simulator which considered contact loss between contact wire and the pantograph as well as contact wire deviation is developed. It is confirmed that a contact wire and pantograph model are necessary for studying the dynamic behavior of the pantograph system. One of the most important needs accompanied by increasing the speed of high-speed train is reduced that an arc phenomenon by loss of contact brings out EMI. In case of a high-speed train using electrical power, as comparison with diesel rolling stock, PLD(Power Line Disturbance) such as harmonic, transient voltage and current, EMI(Electromagnetic Interference), dummy signal injection etc usually occurs. Throughout experiment, it is verified that an arc phenomenon is brought out for simulator operation and consequently conducted noise is flowed in electric circuit by power line disturbance.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제56권4호
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• pp.705-715
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• 2007

Recently, the interest on power quality has been hot issue because the equipments cause voltage disturbance and have become more sensitive to the voltage disturbance. Additionally, the reseach on power electronic equipments applying to the high power has been increased. This paper deals with Line-Interactive Dynamic Voltage Restorer(LIDVR) system using 7-Level H-Bridge inverter, which is one of the solutions to compensate the voltage disturbance and to increase the power of equipments. The LIDVR has the following advantages comparing to the DVR with the series injection transformer. It has the power factor near to unity under the condition of normal source voltage, can compensate the harmonic current of the load and the instant interruption, and has the fast response. First, the construction, the operation mode and algebraic modeling of LIDVR are reviewed. And then the voltage control algorithm is proposed to get the sinusoidal load voltage with constant amplitude. Finally, simulation and experiment results verify the proposed LIDVR system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제27권6호
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• pp.31-38
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• 2013

A pulse driven atmospheric plasma jet controlled by external ballast capacitor is developed. Unlike the most commonly use DBD sources, the proposed device utilizes bare metal electrode. The discharge energy per pulse can precisely be determined by changing voltage and capacitance of the ballast capacitor. It is shown that the device can provide wide range of plasma, from stable glow mode to near arc state. Current-voltage waveforms, optical emission spectra and discharge images are investigated as a function of an injection energy. The OES shows that He and oxygen lines are increased as a function of the external ballast capacitor. Ozone and rotational temperature have similar tendency with a power consumption. The feeding gas is He and the applied DC voltage is from 400V to 800V when the gap distance is $500{\mu}m$.

• Korean Journal of Adult Nursing
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• 제23권4호
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• pp.386-396
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• 2011

Purpose: This study was conducted to examine the level of physical activities at time points of pre-illness and current treatment, and the differences in body mass index (BMI), anxiety, depression and fatigue according to their physical activity in cancer patients undergoing chemotherapy. Methods: The survey was used with 126 cancer patients undergoing daily chemotherapy at injection room, cancer clinic of C University Hospital in G city. Data were collected from June to September, 2009 using a structured questionnaire. The data were analyzed by descriptive statistics, chi-square, Fisher's exact test and t-test using SPSS/WIN15.0. Results: The significant increase in physical activity was reported from pre-illness to the time in treatment (${\chi}^2$=69.027, p<.001). The anxiety level of the group with increased physical activity was significantly lower than those who did not (t=-2.218, p =.028). There were no significant differences in BMI, depression, and fatigue according to physical activity. Conclusion: The level of physical activity was significantly associated with the anxiety level of the cancer patients undergoing chemotherapy. Cancer patients should been encouraged regular physical activity during chemotherapy treatment. And an appropriative nursing intervention should be established in order to motivate cancer patients to increase physical activity.

• Proceedings of the Korea Contents Association Conference
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• 한국콘텐츠학회 2009년도 춘계 종합학술대회 논문집
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• pp.1136-1140
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• 2009

The current population of elderly is increasing and the with an extended average lifespan, the frequency of cancerous occurrences have also increased, with these increases and the increase in radiotherapy for cancer patients, recognitions of harm and importance have become known. This article was known tumor treatment of patients with hematopoietic disorder by doing a comparative study on the changes in blood cells caused by the acute effects of trace dose to high dose of radiation exposed to mice. According to the sensitizer injection may give rise to harm to the components of peripheral blood. This material needs to be considered when for treating tumor patients and the risks of hematopoietic harm and believe that radiation therapy will be reasonable.