• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.72-76
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• 2004

본 논문에서는 일명 델타변환 무정전전원장치(UPS)로서 알려져 있는 3상 라인 인터랙티브 UPS 시스템의 성능 시험에 대해서 다루고 있다. 델타변환 UPS는 종래의 단일 변환 라인 인터랙티브 UPS 시스템에서 직렬 인덕터를 제거하고 직렬 및 병렬 PWM 컨버터를 사용하는 새로운 라인 인터랙티브 UPS 시스템으로 전원 전류를 직접 제어함으로써 UPS 시스템의 입출력 특성들이 상당히 개선되는 것으로 알려져 있다. 여기서는 UPS 시스템의 성능 시험에서 중요한 내용들인 부하시험, 정전/복전시험, 동기절체 시험 등에 대한 결과들을 제시하고 델타변환 UPS 시스템에 대한 전반적인 평가를 한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 추계학술대회 논문집
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• pp.202-205
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• 2003

Recently, UPS(Uninterruptible Power Supply) have been largely used to improve power souse quality as well as to protect critical loads such as computer, industrial system, medical equipment, etc, against power outage by providing clean and uninterrupted power under power supply disturbance or interruptions. But UPS is bulky because used battery. So, UPS size issue have received attention in the power electronics industry. Therefore, this paper proposed a implementation of inside of the computer power supply with UPS by the one-chip microprocessor to minimize UPS size. To verify the proposed power supply, the detail simulation and experiment results indicate that high-frequency switching and operation UPS can be achieved.

• Asian Journal of Innovation and Policy
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• 제7권1호
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• pp.30-54
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• 2018

Tech start-ups and their ecosystems are gaining increasing prominence globally and so are in India, due to their potential to contribute to employment generation, innovations, productivity, national income and exports. Against this backdrop, this article analyzes the key characteristics of tech start-ups relative to traditional start-ups and modern start-ups in India. Further, the salient features of tech start-up promotion policies initiated by the government of India and government of Karnataka as well as the current regional and sectoral distribution of start-ups is elucidated. Subsequently, the structure and components of entrepreneurial ecosystems currently under evolution in the metro cities of India are examined. Finally, the key factors contributing to the growth of different ecosystem components and its implications for the future growth of tech start-ups are outlined.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권8호
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• pp.495-499
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• 2004

UPS(Uninterruptible Power Supply) have been used to improve power source quality as well as to protect critical loads such as computer, industrial system, medical equipment, etc, by providing clean and uninterrupted power under power supply disturbance or interruptions. But UPS is bulky because batteries. So, a UPS size issue has received the attention in the power electronics industry. This paper proposed an implementation of the computer power supply with a bulit-in UPS controlled by the one-chip microprocessor to minimize UPS size. The experimental results verified the proposed SMPS with a bulit-in UPS for computer.

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1072-1077
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• 2006

본 논문은 AC 라인 리액터와 2개의 4레그 PWM 전압형 컨버터를 사용하여 병렬 및 직렬 능동필터 기능을 가지는 새로운 3상 Line-Interactive UPS 시스템을 제안하고 전압제어 방식을 설명한다. 제안하는 UPS 시스템의 병렬 및 직렬 PWM 전압형 컨버터에서 전압제어의 목적은 정상상태 및 과도상태에서 만족스러운 동작 특성을 보장하는 것이다.

• 인터넷정보학회논문지
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• 제19권6호
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• pp.113-123
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• 2018

This study was conducted to empirically verify the effect of the technological entrepreneurship, network capability and technological innovation capability on the innovative performance of technology-based start-ups with the aim of determining the success factors of technology-based start-ups by defining the success of technology-based start-ups as the innovative performance through technology innovation activities. For the significance of this study, it suggested the importance of technology innovation as a survival strategy of technology-based start-ups, verified the dimensions, relationship and roles of technological entrepreneurship, network capability and technology innovation capability, thereby proving the theoretical expansion. This study has determined the success factors of technology-based start-ups and thereby suggested the strategic directions for enhancing the competitiveness of technology-based start-ups.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.390-393
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• 2007

The reliability as well as the power capability of the UPS system can be increased by replacing a single UPS unit with multiple small UPS units in parallel, resulting in a so-called module UPS. This module UPS system allows that a new module can be added or replaced while maintaining power to loads, which is a hot-swappable operation. In addition, it has desirable features such as ease of output power expandability, convenience of maintenance and repair, and high reliability. To realize the module UPS, load sharing without interconnection among parallel connecting modules as well as a small scale and lightweight topology is necessary. The frequency and voltage droop method is applied to parallel operation control to achieve load sharing. 5kVA modules are designed and implemented to confirm the effectiveness of the proposed approaches. Experimental results show that the module UPS system has a high power factor, a low distortion of output voltage and input current, hot-swappable operations and good load sharing characteristics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.437-439
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• 1996

In this paper, an UPS system using high-frequency link AC to DC converter is Proposed. The AC to DC converter has sinusoidal input current and high power factor. In this UPS system, the waveform of the output voltage has smaller harmonic contents than those of a conventional UPS system. In this paper, an operating principle of the system is presented. This new control technique of the UPS system is capable of providing a wide range regulated output DC voltage compared with the conventional UPS system. Performance of the system carried out through theoretical and experimental means.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.605-607
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• 2001

In this paper, an off-tine UPS with CVT(constant voltage transformer) is designed and the experimental result and problems of the designed UPS is given and discussed. This off-line UPS consists of triple-port CVT and PWM inverter which acts as charger and inverter. It can be evaluated in low price because haying simple structure. It offers high performance because CVT restricts the short current automatically about two or three times of rated current, has nearly unit power factor and constant output voltage to varying input voltage. The weak points of this UPS are that the output voltage waveform is not perfect sinusoidal and has phase difference to input voltage. The experimental result and problems of the designed UPS is given.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.258-259
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• 2017

본 논문에서는 병렬 멀티-모듈 UPS 인버터의 출력 LC필터를 이용한 예측제어를 제안한다. 부하의 용량증가에 따라 단상 UPS 모듈을 병렬로 증가시켜 UPS 용량 증설하는 연구가 진행되고 있다. 이러한 UPS 시스템을 제어하기 위해 기존 제안하였던 전류 예측 제어에서는 PI 전압 제어로 인해 UPS 모드 절환 시 제한된 동적 반응(Dynamic response)을 갖는 단점이 있었다. 이러한 문제점을 보완하기 위해, 본 논문에서는 PI 전압제어를 전압 예측 제어로 대체함으로써 보다 빠른 동적 반응을 가질 수 있는 전압 및 전류 예측제어를 제안한다. 제안한 제어기법의 타당성은 수학적 분석 및 시뮬레이션을 통해 검증하였다.