• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2005년도 수소연료전지공동심포지움 2005논문집
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• pp.103-110
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• 2005

Fuel cell systems are consisted of various parts, for example fuel cell stack, fuel supplier, electrical converters, controllers and so on. Each components of system should have appropriate specification for their applications as well as simplicity. Because thermal load can be managed simply by using fans without any water cooling system, the air-cooled PEMFC is widely used in sub kW and around 1kW systems. The performance of an air-cooled system is highly dependent on ambient temperature and humidity. In this paper, the air-cooled PEMFC systems are developed and investigated to study the operating characteristics in the aspect of the thermal and water coupled management by the control of the axial fans and compressors. Various experiments were also conducted to get the cell voltage distribution, the relative humidity of the reactant gas and the thermal management by axial cooling fans, which cannot be observed in single cell experiment. After then, as practical applications, portable fuel cell system and a hybrid electric cart were successfully integrated and operated by using this air-cooled stack.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.318-330
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• 2015

In wearable sensor systems (WSSs), sensor nodes are deployed around human body parts such as the arms, the legs, the stomach, and the back. These sensors have limited lifetimes because they are battery-operated. Thus, transmission power control (TPC) is needed to save the energy of sensor nodes. The TPC should control the transmission power level (TPL) of sensor nodes based on current channel conditions. However, previous TPC algorithms did not precisely estimate the channel conditions. Therefore, we propose a new TPC algorithm that uses an accelerometer to directly measure the current channel condition. Based on the directly measured channel condition, the proposed algorithm adaptively adjusts the transmission interval of control packets for updating TPL. The proposed algorithm is efficient because the power consumption of the accelerometer is much lower than that of control packet transmissions. To evaluate the effectiveness of our approach, we implemented the proposed algorithm in real sensor devices and compared its performance against diverse TPC algorithms. Through the experimental results, we proved that the proposed TPC algorithm outperformed other TPC algorithms in all channel environments.

• Smart Structures and Systems
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• 제6권3호
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• pp.263-275
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• 2010

In the last decade, wireless sensor networks have emerged as a promising technology that could accelerate progress in the field of structural monitoring. The main advantages of wireless sensor networks compared to conventional monitoring technologies are fast deployment, small interference with the surroundings, self-organization, flexibility and scalability. These features could enable mass application of monitoring systems, even on smaller structures. However, since wireless sensor network nodes are battery powered and data communication is the most energy consuming task, transferring all the acquired raw data through the network would dramatically limit system lifetime. Hence, data reduction has to be achieved at the node level in order to meet the system lifetime requirements of real life applications. The objective of this paper is to discuss some general aspects of data processing and management in monitoring systems based on wireless sensor networks, to present a prototype monitoring system for civil engineering structures, and to illustrate long-term field test results.

• 한국산업정보학회논문지
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• 제29권3호
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• pp.67-77
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• 2024

공장의 에너지 효율을 높이는 방안 중 공정 스케줄링은 제조 공정에서 자원을 최적으로 할당하여 제품의 생산 계획을 수립하는 활동이다. 그러나 야간 근로가 불가피한 경우에는 이러한 전략이 효과적으로 적용되지 않을 수 있다. 또한, 생산 요구량의 지속적인 변화로 인해 실제 공장에서의 적용에 어려움이 있다. 최근에는 전기자동차의 보급이 급증함에 따라 전기자동차 배터리를 에너지 저장 시스템으로 활용하는 기술이 주목을 받고 있다. 이러한 배터리를 활용한 기술은 공장 에너지 관리를 위한 대안이 될 수 있다. 본 논문에서는 전기자동차 배터리를 활용한 공장 에너지 관리 방안을 제안한다. 제안된 방안은 전기자동차 배터리 충전 상태 및 TOU(Time-of-use)를 고려하여 PSCAD/EMTDC 소프트웨어에서 분석된다. 제안된 방안은 예측된 전력 사용량과 TOU를 고려하여 수립된 공정 스케줄링과 비교 분석된다. 결과적으로 공정 스케줄링은 하루에 4,152원, 제안된 방안은 7,286원의 전기 요금을 절감하였다. 본 논문을 통해 공장 에너지 관리를 위해 전기자동차 배터리 활용 가능성을 확인할 수 있었다.

• 한국전기전자재료학회논문지
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• 제27권7호
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• pp.417-427
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• 2014

Renewable energy sources such as solar, wind and hydro provides utilizing renewable power and reduce the using fossil fuels. On the other hand, it is too critical to apply power system due to the intermittent nature of renewable energy sources, the continuous fluctuations of the power load, and the storage with high energy density. Energy storage system, including pumped-hydroelectric energy storage, compressed-air energy storage, superconducting magnetic energy storage, and electrochemical devices like batteries, supercapacitors and others have shown that solve some of the challenges. In this paper, we review the current state of applications of energy storage systems, and atomic layer deposition technology, graphene materials on the energy storage systems and processes.

• Journal of Power Electronics
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• 제8권3호
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• pp.217-227
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• 2008

The electric power subsystems (EPS) of most remote sensing satellites consist of a solar array as a source of energy, a storage battery, a power management and control (PMC) unit and a charge equalization unit (CEU) for the storage battery. The PMC and CEU use high frequency transformers in their power modules. This paper presents a design, implementation and testing results of a high frequency transformer for the EPS of satellite applications. Two approaches are used in the design process of the transformer based on the pre-determined transformer specifications. The transformer is designed based on an ETD 29 ferrite core. The implemented transformer consists of one center-tapped primary coil with eleven center-tapped secondary coils. The offline calculation results and measured values of R, L for transformer coils are convergence. A test circuit for measuring the transformer parameters like voltage, current and B-H hysteresis was implemented and applied. The test results confirm that the voltage waveforms of both primary and secondary coils were as desired. No overlapping occurred between the control signal and the transformer, which was not saturated during testing even during a short circuit test of the secondary channels. The dynamic B-H loop characteristics of the used transformer cores were measured. The sample test results are given in this paper.

• 전기학회논문지P
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• 제64권1호
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• pp.18-22
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• 2015

When using a secondary battery in energy storage units, if the grid is in light duty the active power is stored so it can be used when the grid is in heavy duty. This makes possible for the load equalize and make the grid optimized. Recently the government is trying to propagate this technology. Depending on its capacity this kind of electric energy storage unit is used in adjusting the frequency, break up the energy peak in summer and winter, stabilize the energy output of renewable energy which can change unstably because of the environment. Which makes it possible to stabilize the grid. It is anticipated that market of 120 trillion won will be developed worldwide in 2030. Currently in Korea a steady supply is in progress. However because of stray electromagnetic waves some other electronics are malfunctioning. This paper covers the research in the method to detect the emission noise in small electric energy storage units using lithium secondary batteries and battery management system, Power conditioning systems with CIPSR standards. And the research of a more efficient method to measure such stray electromagnetic waves.

• 대한임베디드공학회논문지
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• 제3권1호
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• pp.42-48
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• 2008

The architecture of WSN based Vehicle Speed Measurement System is presented in this paper from Telematics Sensor Network(TSN) to Management System. To verify the feasibility of the system, we implemented the vehicle speed measurement system and evaluated the accuracy of velocity measured by the system in our testbed, an old highway located near Kyungbu highway. The system performed over 95% of accuracy at 80kmph from the measurement. In addition, the battery life time of the sensor node was evaluated by simulation analysis with real measured current consumption profiles. Assuming the maximum average daily traffic in 2005, the battery life time is expected to be over 1.6 year from the simulation result.

• 전기학회논문지
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• 제65권2호
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• pp.264-268
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• 2016

Recently, various energy efficiency optimization activities are ongoing globally by integrating conventional grids with ICT (Information and Communication Technology). In this sense, various smart grid projects, which power suppliers and consumers exchange useful informations bilaterally in real time, have been being carried out. The electric vehicle diffusion program is one of the projects and it has been spotlighted because it could resolve green gas problem, fuel economy and tightening environmental regulations. In this paper, the economics of V2G system which consists of electric vehicles and the charging infrastructure is evaluated comparing electric vehicles for V2G with common electric vehicles. Additional benefits of V2G are analyzed in the viewpoint of load leveling, frequency regulation and operation reserve. To find this benefit, electricity sales is modeled mathematically considering depth of discharge, maximum capacity reduction, etc. Benefit and cost analysis methods with the modeling are proposed to decide whether the introduction of V2G systems. Additionally, the methods will contribute to derive the future production and the unit cost of electric vehicle and battery and to get the technical and economic analysis.

• 디지털정책학회지
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• 제1권2호
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• pp.47-52
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• 2022

드론 비행의 위치 인식에 있어 GPS 신호의 절대적 의존성, 비행 안정성, 배터리 한계로 인한 비행시간 문제는 드론 산업 발전의 큰 제약이 되고 있다. 특히 20분 내외의 짧은 임무 비행시간은 드론 활용에 있어 큰 걸림돌이 되고 있으며, 이를 극복하기 위해 액체수소를 에너지원으로 이용한 드론개발이 활발히 진행되고 있다. 하지만 액체수소 드론개발의 속도보다 현재의 규제 및 인증 제도 개정의 속도가 더뎌 개발 드론의 시험, 인증, 상용화에 어려움을 겪고 있으며, 이는 결국 드론 시장 선점의 문제점이 되고 있다. 본 논문에서는 수소 에너지 기반 드론개발 동향을 분석하며 규제와 인증 제도의 한계점을 소개하고 해결방안을 간략히 제시한다.