• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.98-99
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• 2007

전력계통을 감시하고 운영하는 핵심설비인 EMS는 다양한 서버들과 통신장치, 보안장치 및 환경설비 등으로 구성되어 있다. 이들 설비는 네트워크 망에서 데이터를 상호교환하면서 고유의 역할을 수행하며, 특정 설비의 장애는 시스템 전체에 혼란상황을 가져올 수 있다. 따라서 EMS를 구성하는 각종 설비들을 종합하여 실시간으로 감시하는 시스템이 필요하며, 이는 운용자에게 장애발생을 신속히 통보함으로서 시스템의 빠른 복구를 가능하게 한다. 아울러 실시간으로 감시한 시스템 성능데이터를 데이터베이스화함으로서 과거 성능을 분석하고 미래의 사용 추이를 예측할 수 있다. 이처럼 EMS 고유 특징을 고려한 감시시스템을 구축하기 위해서는 다양한 통신 프로토콜을 수용할 수 있는 통합 어댑터 모듈을 개발, 감시시스템에 수용하여야 한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.99-106
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• 2010

This paper proposes a novel design of enhanced auto light control system using PLC(Power Line Communication) and SMS(Short Message Service) to copy with emergent cases effectively. In the proposed system, the indoor sensing system is designed to send emergent messages to the users or system manager in case of fire or invasion, which may prevent secondary accident. In addition, data transmission using PLC may drastically decreases the number of lines. The experimental results show the effectiveness of the proposed system.

• Korean Journal of Construction Engineering and Management
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• v.19 no.3
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• pp.33-42
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• 2018

In the aftermath of an earthquake, seismic-damaged infrastructure systems loss estimation is the first step for the disaster response. However, lifeline systems' ability to supply service can be volatile by external factors such as disturbances of nearby facilities, and not by own physical issue. Thus, this research develops the bayesian model for probabilistic inference on common-cause and cascading failure of seismic-damaged lifeline systems. In addition, the authors present network robustness estimation metrics in the context of failure propagation. In order to quantify the functional loss and observe the effect of the mitigation plan, power and water supply system in Daegu-Gyeongbuk in South Korea is selected as case network. The simulation results show that reduction of cascading failure probability allows withstanding the external disruptions from a perspective of the robustness improvement. This research enhances the comprehensive understanding of how a single failure propagates to whole lifeline system performance and affected region after an earthquake.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1183-1194
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• 2021

Traditionally, electric power systems have been known as the centralized structures, which is organized into placing customers at the end of the supply chain. However, recent decades have witnessed the emergence of distributed energy resources(:DERs) such as rooftop solar, farming PV system, small wind turbines, battery energy storage systems and smart home appliances. With the emergence of distributed energy resources, the role of distributed system operators(:DSOs) will expand. The increasing penetration of DERs could lead to a less predictable and reverse flow of power in the system, which can affect the traditional planning and operation of distribution and transmission networks. This raises the need for a change in the role of the DSOs that have conventionally planned, maintained and managed networks and supply outages. The objective of this research is to designed the future distribution operation system with multi-DERs and the proposed distribution system model is implemented by hardware-in-the-loop simulation(HILS). The test results show the normal operation domain and reduction of distribution line loss.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3172-3174
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• 1999

교환기나 전송장치 등 각종 통신설비에 전원을 공급하기 위해서 정류기, 축전지 및 발전기 등의 전원설비가 사용되고 있다. 이들 중에서도 정류기는 통신설비에 직류전원을 공급하기 때문에 다른 전원설비 보 다도 신뢰성 및 안정성이 확보된 장치로 인식되어 왔다. 그러나 현재 사내전화국에 설치 운용중인 정류기는 교환 기별로 종류가 다양하여 유지보수에 어려움이 내재하고 있을 뿐만 아니라 통신망의 광대역화, 대용량화에 대처가 곤란하며 정류기를 전력실 또는 통신실에 집중해서 설치 운용하는 집중공급방식으로는 축전지의 만충전이 곤란하다. 또한 현재의 이러한 급전방식은 통신장치의 광대역화, 고도화 등 통신망의 급격한 발전과 함께 다음과 같은 문제점이 대두되고 있다. 첫째, 전력실에서 총괄하여 교류전력을 직류48V로 변환해서 급전하기 때문에 급전전류가 크게되고, 또한 전력실에서 통신실까지의 급전손실이 크다 둘째, 통신설비의 증감에 따른 전원설비의 증감이 어렵기 때문에 설비 가동율이 나쁘다 셋째, 전원설비의 고장에 의한 전화국 전체설비에 심각한 영향을 미칠수 있다 이러한 문제점을 해소하기 위하여 집중 및 분산급전방식으로 운용이 가능하며, 또한 모든 전원설비를 감시/제어하는 전원 집중관리 시스템과의 인터페이스 등이 가능한 정류시스템을 1997년부터 개발하였다. 본고에서는 신형 정류기와 기존의 정류기와의 성능 및 특성에 대해 비교하였고, 특히 경제성측면과 설치상련에 대해 비교분석 하였다. 또한 집중급전방식과 분산급전방식의 특성에 대해서도 서술하였다.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.11
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• pp.517-526
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• 2008

As the functionality of portable devices arc being enhanced and the performance is being greatly improved, power dissipations of battery driven portable devices are being increased. So, an efficient power management for reducing their power consumption is needed. In this paper, we propose a window-based DVS algorithm for MPEG Player. The proposed algorithm maintains the recently frame information and execution time received from MPEG player in window queue and dynamically adjusts (frequency, voltage) level based on window queue information. Our algorithm can be implemented in the common multimedia player as a module. We employed well-known MPlayer for the measurement of performance. The experimental result shows that the proposed algorithm reduces energy consumption by 56% on maximal performance.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.3
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• pp.459-464
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• 2023

The mobile house of this article is provided with stand-alone power system that uses photovoltaic energy and enables sensing and environmental monitoring. Excess power generated is stored in lithium batteries, which enable smooth operation of the mobile house even in environment in which solar energy cannot be used. The house has been designed that its systems can be operated continuously by diesel power generation even when photovoltaic energy cannot be generated due to long rainy season or heavy snow. BMS (batter management system) has been constructed for photovoltaic and power management, and monitors the charge/discharge and usage amount of photovoltaic energy. Various sensing data are recorded and transmitted automatically, and the design allows for wireless monitoring by means of computer and smartphone app. The container house proposed in this study enables efficient energy management by performing optimal energy operation in remote areas, parks, event venues, and construction sites where there is no system power source.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.129-135
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• 2017

Recently, with the development of IoT technology, there has been an increase in interest in the power consumption of the devices used by the internal devices. Especially, the standby power consumption during the main function of the devices is about 11% of the power energy and the problem of standby power interruption is suggested. However, there is a problem that the plug must be unplugged in order to substantially shut off standby power. Therefore, in this paper, we design and implement a standby power cutoff algorithm that can automatically control and manage users' participation in order to solve there problems. As a result of evaluating the implemented system, it was confirmed that the standby power interruption rate improved by about 5.89Wh on average compared to the existing system.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.774-777
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• 2011

산업제어시스템(ICS: Industrial Control System)은 전력 생산, 댐 운영, 가스 생산, 수자원 관리, 원자력 발전 설비 등의 운영을 제어하고 관리하는 시스템이다. 대부분의 국가 기반 시설은 이러한 제어시스템에 의해 관리되고 있으며, 정보통신 기술이 발전하면서 업무망과 제어시스템망을 나누워 구축하며 점차 개방화되어 가고 있다. 이로 인한 IT측면에서 발생하는 사이버 공격이 비교적 폐쇄적인 제어 시스템 망으로 언제든지 이루어질 수 있으며, 실제 국내에서 독립적인 네트워크를 사용함에도 불구하고 금융권의 전산망이 마비되는 사태가 발생하였다. 또한 국외에서는 이란의 원자력 발전소 제어 시스템을 목적으로 하는 'Stuxnet' 악성코드로 인해 발전소 운용이 중단돼는 사례도 발생하였다. 산업용 시스템의 목적과 특성상 사이버 침해사고 발생 시 국가적 손실 및 생명에도 위협을 받을 수 있다. 본 논문은 과거에 보안을 고려하지 않고 구축되었던 제어시스템을 사이버 침해로부터 보호하기 위해 제어시스템을 위한 통신 프로토콜 암호화 및 화이트리스트보안 기술을 이용한 시스템 적용 방안을 소개하며, 네트워크 접속시 인가된 산업용 PC의 안전성을 평가하기 위해 요구되는 보안 플렛폼 설계를 한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.2
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• pp.134-141
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• 2010

Small PEM (Proton Exchange Membrane) fuel cell systems do not require humidification and have great commercialization possibilities. However, methods for controlling small PEM fuel cell stacks have not been clearly established. In this paper, a control method for small PEM fuel cell systems using a dual closed loop with a static feedforward structure is defined and realized using a DSP (Digital Signal Processor). The fundamental elements that need to be controlled in fuel cell systems include the supply of air and hydrogen, water management inside the stack, and heat management of the stack. For small PEM fuel cell stacks operated without a separate humidifier, fans are essential for air supply, heat management, and water management of the stack. A purge valve discharges surplus water from the stack. The proposed method controls the fan using double control loops to quicken transient response of the fan thereby improving the supply rate of air. Feedback control to compensate for the voltage change in fuel cell stack improves the response characteristics in fuel cell to load variations. The feasibility of proposed method was proved by the experiments with a 60W small PEM fuel cell system and operation of a notebook computer using this system.