• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.499-508
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• 2008

Frequency regulation in off-normal conditions has been an important problem in electric power system design/operation and is becoming much more significant today due to the increasing size, changing structure and complexity of interconnected power systems. Increasing economic pressures for power system efficiency and reliability have led to a requirement for maintaining power system frequency closer to nominal value. This paper presents a decentralized frequency control framework using a modified low-order frequency response model containing a proportional-integral(PI) controller. The proposed framework is suitable for near-normal and emergency operating conditions. An $H_{\infty}$ control technique is applied to achieve optimal PI parameters, and an analytic approach is used to analyse the system frequency response for wide area operating conditions. Time-domain simulations with a multi-area power system example show that the simulated results agree with those predicted analytically.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.914-919
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• 1998

A Capacitor Commutated Converter (CCC) has less difficulty of commutation failure in comparison to the conventional line commutated converter. This paper proposes the Ar1R control of the CCC in the inverter operation, which deserves as the Ar1R of the conventional converter. The CCC can be operated in high power factor area by using the proposing Ar1R control. The voltage stability at an AC bus connected the CCC inverter is investigated and estimated its ability of preventing the AC voltage collapse. To estimate the voltage stability, this paper developed the simplified converter mathematical model and led the VSF index. The results shows that the AC voltage stability is guaranteed and enables the interconnection to an weak AC system, when compensation factor of the compensation capacitor is higher than 200%.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.77-80
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• 2003

As rapid growth of energy demand in line with modern society's industrialization led to environmental pollution by fossil fuels, there are more and more interest and international research on energization of water, which is clean energy and comprising $70\%$ of earth. In offshore countries, the water is commercially used already and water has very attractive characteristics in terms of economy and efficiency compared to the existing gas welder. Brown Gas welder does not produce $CO_2$ from combustion of Hydrogen-Oxygen-Gas, which was gained by electrolysis of water, In this paper, the result from operating characteristic improvement of Gas Generator and Current-Controlled converter is to be considered into design in electrode, source/ controller, standized into level of whole system design base.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.132-135
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• 2005

본 연구에서는 반도체 제조 공정에 이용되는 가스의 흐름을 감지하고 제어하는 장치를 제안하였다 압력센서를 MFC(Mass Flow Controller)에 의해 제어되는 다음 단의 파이널밸브(Final Valve)와 챔버사이의 가스관에 부착시켜, 이 압력센서의 신호와 공압밸브의 동작 신호를 디지털 회로를 이용하여 실시간으로 제어하도록 하였다. 이로써 반도체 제조 공정 중에 발생할 수 있는 2차 소성물로 인한 가스의 흐름 제어와 관련된 시스템 고장을 LED를 통해 실시간으로 확인 가능하다. 또한 가스누출고장발생 시 반도체 제조 공정의 프로세스를 중단시켜 장비의 손상 및 안전사고를 예방하는 기능도 있다. 본 연구에서 개발된 모듈을 이용함으로써 가스밸브의 오동작에 의한 반도체/디스플레이 제조장비의 신뢰성 향상을 기할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.510-513
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• 2017

자전거 이용자 급증으로 자전거의 도난 및 분실을 방지하여 사용자를 안심시켜주고 주행 중 위험요소를 줄이고자 하는 목소리가 높아지고 있다. 본 논문에서는 애플리케이션 개발을 위해 MCU(Micro Controller Unit)인 Arduino Mega 2560 기반에 블루투스(Bluetooth) 통신 방식을 사용하여 자전거 잠금장치, 위치 추적 장치를 조작하고 후방 감지 장치를 제어하였으며 초음파 거리센서 값을 이용하여 LED Strip 및 진동 모터로 사용자에게 주행 상태를 알리는 장치를 구현하였다.

• Proceedings of the KIEE Conference
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• summer
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• pp.1242-1244
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• 2004

As rapid growth of energy demand in line with modem society's industrialization led to environmental pollution by fossil fuels, there are more and more interest and international research on energization of water, which is clean energy and comprising $70\%$ of earth. In offshore countries, the water is commercially used already and water has very attractive characteristics in terms of economy and efficiency compared to the existing gas welder. In this paper, the result from operating characteristic improvement of Gas Generator and Current-Controlled converter is to be considered into design in electrode, source and controller, standized into level of whole system design base.

• Science of Emotion and Sensibility
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• v.23 no.4
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• pp.105-116
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• 2020

The purpose of this study is to progress the limitations and disadvantages of existing safety clothing by applying high technology to current safety clothing that is produced and distributed only with fluorescent fabrics and retroreflective materials. Therefore, the industrial suspender-type safety belt and engineering technology are introduced, designed, and fabricated to help save a life in an emergency. First, the suspender-type safety belt to be developed is designed to emit light by LED attached to the film, and the body of the belt-wearer is recognized from a distance through retroreflection from the flashing LED. It aims to support people's safety by preventing accidents during roadside work, rescue activities, and sports activities at night. Second, with the development of advanced devices when the user is in an unconscious state due to distress or falls into an unconscious state due to distress or accident, the tilt sensor of the control unit attached to the belt automatically detects the angle of the human body and generates light and sound. It is intended to further enhance the utilization by mounting a sensing and signaling device that generates a distress signal and shaping it in the form of a belt attached to a vest that can be easily detached from the outside of the garment. When the wearer falls due to an accident, the tilt sensor of this belt detects the angle change and then the controller generates a high-frequency sound and repeated LED blinking signals at the same time. In the case of conventional safety vests, it is almost impossible to detect that the person is wearing a vest when there is no ambient light, but in case of the safety belts in this study, the sound and light signals of the safety belt enable us to find the wearer within 100 meters even when there is no ambient light.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.269-274
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• 2013

To proportionally control the electronic valve position of the actuator, we designed and fabricated PCU, CPT, and rotary absolute optical encoder for the detection of absolute angular position in the actuator. We also designed and constructed the test system by using DAQ hardware and Labview. We designed PCU to convert 1-5 V, 0-5 V, 0-10 V, 2-10 V voltage signals and 4-20 mA current signals to the voltage signals in the common 0.5-2.5 V range. We designed CPT to output 4-20 mA current signals corresponding to the valve positions based on the PWM signal input from the MCU. We also designed 20 bit optical encoder by using infrared LED and infrared transistor and made the serial communication with the main board possible. When we tested PCU and CPT with DAQ hardware and Labview software, they operated correctly with the small errors within ${\pm}0.003$ V and ${\pm}0.01$ mA, respectively, showing that our actuator has the excellent performance to employ as the industrial proportional-valve-actuator. The resolution of the encoder was $11.25^{\circ}$ and the maximum revolution to detect was 32,768.

• The Journal of the Korea Contents Association
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• v.20 no.9
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• pp.271-284
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• 2020

Good reviews that Half-Life: Alyx received created a turning point for the vitalization of the VR market with an uncertain future due to the absence of a revenue model together with the increased sales of VR equipment. Based on previous studies, this study categorized the characteristics of VR games according to graphs, first-person system, interface, controller, interaction technology, sound and stories. The analysis results show that the seven elements corresponded with "interactions" and "virtual images," which represent the completion level of games as part of VR components, and were connected to one another, which led to the proposal of an upper-rank concept "presence" to put them together. "Immersiveness," which represents users' emotions as part of VR components, was analyzed with the immersion theory to assign tasks of proper difficulty level for users' abilities. In the research process, the Delphi technique and FGI were administered to a panel of 15 experts to ensure objectivity. Finally, "presence" and "immersiveness" are characteristics in proportion to each other and can be valid concepts in future analysis of VR games as well as Half-Life: Alyx, which led to the proposal a new concept framework called 'presence effects' by combining the two words.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.247-253
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• 2011

In this paper, we propose and implement the automated brightness control system using distance measuring sensor for reducing the power consumption of emotional lighting device. In order to reduce the power consumption of emotional lighting devices which express continuous color changes, the proposed device measures the distance continuously using ultrasonic sensor and by using this, it also performs PWM Dimming control. The lighting device is composed of micro controller, LED driver, ultrasonic sensor, communication module and so on. And the device performs the real time brightness control by adapting the measured distance information from ultrasonic sensor to PWM signals. From this experiment, we implement the active lighting system which minimizes unnecessary power consumption during user's absence by adapting existing energy reducing techniques.