• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권8호
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• pp.405-412
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• 2003

This paper presents a three-phase Line-Interactive uninterruptible power supply (UPS) system with series-parallel active power-line conditioning capabilities, using synchronous reference frame (SRF) based controller, which allows an effective power factor correction, source harmonic voltage compensation, load harmonic current suppression, and output voltage regulation. The three-phase UPS system consists of two active power compensator topologies. One is a series active compensator, which works as a voltage source in phase with the source voltage to have the sinusoidal source current and high power factor under the deviation and distortion of the source voltage. The other is a parallel active compensator which works as a conventional sinusoidal voltage source in phase with the source voltage, providing to the load a regulated and sinusoidal voltage with low THD (total harmonic distortion). The control algorithm using SRF method and the active power flow through the Line-interactive UPS systems are described and studied. The simulation and experimental results are depicted in this paper to show the effect of the proposed algorithm.

• KIEAE Journal
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• 제15권3호
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• pp.93-99
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• 2015

Purpose: Various studies on the soil-based green roof systems have been conducted, and a lot of green roof systems were developed. A growing medium board is one of them which was developed for better application and maintenance, however the effect and performance of this material need to be verified. On this background, the purpose of this study is to prove cooling load reduction of green roof by monitoring experiment on the full-scale mock-ups. Method: To do this, Solid growing medium boards were installed on the mock-ups, and indoor temperature and humidity were monitored and analyzed. Result: As a results, the green roof with solid growing medium board were verified effective for controlling indoor temperature in summer.

• 산업경영시스템학회지
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• 제43권1호
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• pp.132-142
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• 2020

Many countries around the world are pursuing various support policies to foster start-ups national widely in order to secure new economic growth engines in the era of the Fourth Industrial Revolution. The South Korean government announced the diffusion strategy for the 2'nd round Start-up Boom in March 2019 and is promoting the support policies for start-up incubating by various programs. Many incubators and startup accelerators operate various kinds of programs to foster start-ups using government financial supports. The purpose of this study is to investigate the effects of entrepreneurship and technical capability of entrepreneurs as the internal factors of the technology-based start-ups and the effects of programs supported by the government as an external factor on the corporate performance of a start-up company, and the mediating effects of core competence of start-ups were analyzed using SPSS and AMOS. The results show that the entrepreneurship, technical capability and the programs supported by incubators or accelerators had no direct effects on the corporate performance of a start-up, but the core competence of the company had complete mediating effects. In addition, the type of program supported by the comprehensive accelerator programs or the marketing supports had effects on the core competence rather than simple financial supports. Lastly, the policy proposals for incubating program support and future research directions along with the limitation are suggested.

• 대한치과보철학회지
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• 제38권6호
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• pp.757-764
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• 2000

Statement of the problem. All-ceramic post-and-core restorations offer a number of advantages compared with systems that use metal build-ups. In certain clinical cases, however, fractures at the joint between the post and core build-up have been reported. Purpose. The objective, therefore, is to improve the joint between the post and the core build-up. Material and methods. Three different methods were used to prepare all-ceramic post-and-core restorations; pressing IPS Empress core build-ups to CosmoPost zirconia posts, cement-ing IPS Empress core build-ups to CosmoPost zirconia posts and Celay-milling of zirconia blanks. A series of ten restorations was prepared for each of the three methods. The post-and-core complexes were tested to failure with the load applied perpendicular to the post axis. The load and deflection at fracture were recorded. Results. The highest breaking load and highest deflection were recorded for the cementing technique with values of 25.3 N and $394{\mu}m$, respectively, The corresponding values for the pressed core build-ups and the milled zirconia core build-ups were 22 N and $301{\mu}m$, and 13 N and $160{\mu}m$, respectively. All the differences are statistically significant (p=0.05). Regarding the load-dependence of the deflection, the cemented core build-ups again demonstrated the highest value with $15.5{\mu}m/N$. The difference in the values of $13.6{\mu}m/N\;and\;13{\mu}m/N$ recorded for the pressed-on and milled core build-ups, respectively, were statistically insignificant. Conclusion. In regard to the high fracture resistance of zirconia post, adhesive cementing the core build-up to the post offers a viable alternative to the conventional pressing technique. The elastic bond between the rigid high-strength zirconia post and the core build-up presents an additional advantage.

• 전력전자학회논문지
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• 제16권1호
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• pp.20-29
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• 2011

본 논문에서는 동특성이 느린 용융탄산염 연료전지 (Molten Carbonate Fuel Cell, MCFC) 스택을 사용하여 계통사고 시 추가적인 UPS (Uninterruptible Power Supply) 없이 비상부하 (Critical Load)로 전력 공급이 가능하고, 사고 발생 후에도 정격전력으로 발전 가능한 비상부하 추종형 백업 시스템을 제안한다. 제안된 MCFC 발전 시스템용 비상부하 추종형 백업 시스템은 3상 인버터로 구성된 PCS (Power Conditioning System) 출력단에 3상 PWM 컨버터를 연결한 구조이고, 비상부하 추종이 가능한 추가적인 제어 알고리즘을 가지는 Load Leveler를 제어한다. 제안된 비상부하 추종형 백업 시스템의 회로와 제어 알고리즘의 타당성을 5kW 기반의 컴퓨터 시뮬레이션을 통하여 검증한다.

• 한국ITS학회 논문지
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• 제11권5호
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• pp.1-6
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• 2012

현대의 도시교차로는 과거와 달리 날로 이용량과 시설규모가 증가하여 대형화하고 있다. 이에 따라 지역적 정전이나 광역적 정전사태가 발생하는 경우 교통상황은 걷잡을 수 없는 혼잡상황에 직면하게 된다. 최근에는 전력수요예측 오류로 인한 대규모 도시정전사태가 발생한 사례가 있으며, 이로 인한 교통 혼잡해소에 많은 시간과 비용이 소모된 바 있다. 이에 정부와 경찰청에서는 교통신호시스템의 비상대응력을 고도화하기 위해 무정전전원장치(UPS: Uninterruptible Power Supply)의 도입을 추진 중에 있다. 본 연구에서는 교통신호기의 제어 용량을 고려하여 최소 2시간 지속가능한 전원보상용량을 산정하고, 산정 용량을 기준으로 개발된 규격은 시제품 실험을 통하여 전원보상 요구 성능을 검증하였다. 실험결과 개발된 규격은 충분히 요구 성능을 만족하였으며 중요교차로 등 대형교차로에서 운영 가능한 것으로 나타났다.

• 제어로봇시스템학회논문지
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• 제20권2호
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• pp.163-169
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• 2014

Using the classical cascade voltage control strategy, this paper proposes an analytical solution to an MPC (Model Predictive Control) problem with a hexagonal input constraint set for the inner-loop to regulate the output voltage of the UPS (Uninterruptible Power Supply). Focus is placed on how to deal with the hexagonal input constraint set without any approximation. Following the conventional cascade voltage control strategy, the PI (Proportional-Integral) controller is used in the outer-loop in order to regulate the output voltage. The simulation results illustrate that the capacitor voltage rapidly goes to its reference in a satisfactory manner while keeping other state variables bounded under an unexpected load changes.

• 한국콘텐츠학회논문지
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• 제6권1호
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• pp.54-63
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• 2006

본 논문에서는 레거시 시스템에 대한 기존 도메인 분석의 문제점을 해결하기 위하여 동적 모델링을 기반으로 하는 확장된 워크플로우 메커니즘을 이용한 도메인 분석 방법론을 제안한다. 이 방법론을 WODA(Werldlow Oriented Domain Analysis)라 명명한다. 제안하는 절차를 통해 공통/비공통 컴포넌트를 식별 및 컴포넌트들의 클러스터를 추출할 수 있다. 이를 통해 새로운 시스템을 개발 시 효율적으로 재사용하고자 한다. 동적 분석으로 특정한 시스템에 발생 가능한 시나리오들을 식별한 후, 제안한 컴포넌트 테스트 플랜 매트릭스를 이용해 재사용성이 높은 컴포넌트와 컴포넌트 시나리오를 결정한다. 또한 컴포넌트 가중치 측정을 통해 재사용 가능한 컴포넌트들의 중요성과 빈도수를 인식하고 컴포넌트 시나리오들의 우선순위를 도출 할 수 있다. 구현한 자동화 모델링 도구인 WODA을 통해 UPS(Uninterrupted Power Supply)에 적용 사례를 소개한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.1919-1923
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• 1997

Superconducting magnet energy storage(SMES) offers lower loss and more capacity than other energy storage systems. This paper deals with a configuration and a control method of uninterruptible power supply(UPS) with SMES, Proposed system is constituted of three partsinverter, dc chopper and superconducting coil. The control system is implemented with a general-purpose DSP, TMS320C31. The results of simulation and experiment with a 10kVA prototype show the validity of the system configuration and the control method.

• 한국전기전자재료학회논문지
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• 제11권7호
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• pp.565-570
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• 1998

Recently a few MJ superconducting magnetic energy storage ($\mu$ SMES) devices become commerci-ally available as one of the energy storage devices for uniterruptible power supply (UPS) systems. For such a ($\mu$ SMES) devics, a few kA class superconducting cables with high current density, high stability and excellent pulse characteristics are required. To acquire data for the superconduction cables related to design and fabrication of a 0.7 MJ $\mu$ SMES device, we tested critical currents and quench characteristics for several winding tensions and various remping rates especially. It is shown from the results that winding tensions have much influence on quench currents of the $\mu$ SMES devices.