• Journal of Power Electronics
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• v.16 no.4
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• pp.1396-1406
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• 2016

A novel controller design is presented for the recently proposed electric springs (ESs). The dynamic modeling is analyzed first, and the initial Bode diagram is derived from the s-domain transfer function in the open loop. The design objective is set according to the characteristics of a minimum phase system. Step-by-step optimizations of the Bode diagram are provided to illustrate the proposed controller, the design of which is different from the classical multistage leading/lagging design. The final controller is the accumulation of the transfer function at each step. With the controller and the recently proposed δ control, the critical load voltage can be regulated to follow the desired waveform precisely while the fluctuations and distortions of the input voltage are passed to the non-critical loads. Frequency responses at any point can be modified in the Bode diagram. The results of the modeling and controller design are validated via simulations. Hardware and software designs are provided. A digital phase locked loop is realized with the platform of a digital signal processor. The effectiveness of the proposed control is also validated by experimental results.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.1 no.1
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• pp.42-49
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• 1983

전산기의 신뢰도(reliability)라 함은 사용자가 제출한 입력에 대하여 전산 기가 제공하는 결과의 신빙성의 척도라할 수 있는데, 이것은 주어진 전산기의 부 분품 하나하나가, 그리고 프로그램의 하나하나의 instruction이 설계당시에 목적한 성능을 얼마나 잘 유지하고 있는가를 측정하는 척도라고 볼 수 있습니다. 이 신 뢰도는 전산기의 수명, 필요할 때 전산기가 가동할 확율, 또는 전산기의 성능으로 나타낼 수 있습니다. 제2세대 이전의 전산기들에서는 전자공업과 전산기 기술의 불충분한 발전으로 인하여 비용과 기계의 크기의 한정 때문에 신뢰도 향상을 위 한 대책이 거의 없었습니다. 따라서 현재 볼 수 있는 American Air Line의 SABRE(Semi Automatic Business Research Environment), Bell 전화 연구소의 ESS-I, II, III(Electronic Switching System), IBM의 FMS(Future Manufacturing System)과 같은 real-time 씨스템으로서의 응용분야의 개발은 상 당히 어려운 문제였습니다. 그러나 전자공업의 비약적인 발전에 힘입어 금세대의 범용전산기의 설계가 가능하게 되었고, 오퍼레이팅 씨스템의 발전으로 인하여 multiprogramming, time-sharing, real-time 씨스템 등의 응용분야의 개발이 활발 하게 되었습니다. 이러한 응용분야의 활발한 개발과, 대규모 집적회로 (LSI)의 개 발로 ROM(Read Only Memory)의 가격화, 그리고 microprogram의 보급 등으로 특수 목적의 time sharing operation을 위한 소형 전산기가 발전하게 되었으며 종 래의 범용 전산기 대신에 CDC의 string unit과 pipeline을 이용한 STAR 100과 일리노이 대학의 256processor와 Burrough의 B6500로 구성된 ILLIAC-IV와 같은 초대형 전산기가 등장하게 되었습니다.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.6
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• pp.55-61
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• 2018

This study aims to analyze the performance of Heated-nonslip using renewable energy to prevent nonslip freezing during winter. For this purpose, power generation system and congratulatory devices using solar energy are designed, and it is designed to provide regular electricity to heat up nonslip through Electrical storage system(ESS). In this study, It is intended to analyze the level of electrical energy suitable for nonslip using 24V or 48V, and to measure the temperature changes and temperature distribution according to the location of the test object. As a result of the experiment, nonslip's frame temperature was measured at $-7.5{\sim}-5^{\circ}C$ on average, and $-1{\sim}-2^{\circ}C$ on the heating cable during the supply of 24V and this could not be the solution for defrosting freezing nonslip in the winter. As a result of heating nonslip by supplying 48V with an electrical power of 8W, the temperature of the nonslip was shown to be between $5^{\circ}C$ and $11^{\circ}C$ to $13^{\circ}C$. Even if the power supply was switched on and off every minute, the temperature did not drop below $4^{\circ}C$ and the frozen ice melted on the nonslip without freezing.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.491-499
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• 2021

Batteries are widely used for energy storage, such as ESS(Energy Storage System), electric vehicles, electric aircraft, and electric powered ships. Among them, a submarine uses a high power battery for an energy storage. When the battery of a submarine is discharged, a diesel generator generates AC power, and then AC/DC power converter change AC power to DC power for charging the battery. Therefore, in order to lower the current capacity of the diesel generator, it is necessary to use an AC/DC converter with a high input power factor. And, a power converter with a large power capacity must have high stability because it can lead to a major accident when a failure occurs. However, the control algorithm using the traditional PI controller is difficult to satisfy stability and dynamic characteristics. In this paper, we design the high power AC/DC converter with high input power factor for battery charging systems. And, we propose a stable control algorithm. The validity of the proposed method is verified through simulation and experiments.

• Electronics and Telecommunications Trends
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• v.39 no.1
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• pp.83-94
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• 2024

There have been continuous requirements for developing more reliable energy storage systems that could address unsolved problems in conventional lithium-ion batteries (LIBs) and thus be a proper option for large-scale applications like energy storage system (ESS). As a promising solution, aqueous metal-ion batteries (AMIBs) where water is used as a primary electrolyte solvent, have been emerging owing to excellent safety, cost-effectiveness, and eco-friendly feature. Particularly, AMIBs adopting mutivalence metal ions (Ca²⁺, Mg²⁺, Zn²⁺, and Al³⁺) as mobile charge carriers has been paid much attention because of their abundance on globe and high volumetric capacity. In this research trend review, one of the most popular AMIBs, zinc-ion batteries (ZIBs), will be discussed. Since it is well-known that ZIBs suffer from various (electro) chemical/physical side reactions, we introduce the challenges and recent advances in the study of ZIBs mainly focusing on widening the electrochemical window of aqueous electrolytes as well as improving electrochemical properties of cathode, and anode materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5067-5073
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• 2015

Recently, various researches about water resources management system have been conducted in order to handle many problems, for example, climate change can provoke rapid change of water circulation, continuous population increase, population concentration phenomenon and so on. For population concentration region, many researches about water resources management system have been carried out, but many regions far away from civilization have not been handled as research topics. Especially these regions always need electricity supply infra, but significant costs will be required to construct the infra. Therefore this paper presents a methodology in order to generate the electricity from new renewable energy resources and supply the electricity into these region. For this, solar thermal generation system was experimentally studied. Moreover, this solar power generation system was considered as an important component to establish an ESS (Energy Storage System).

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.228-238
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• 2010

There is an increasing interest in research to help overcome the energy crisis that has been focused on energy storage applications in various parts of power systems. Energy storage systems are good at enhancing the reliability or improving the efficiency of a power system by creating a time gap between the generation and the consumption of power. As a contribution to the various applications of storage devices, this paper describes a novel algorithm that determines the power and storage capacity of selected energy storage devices in order to improve upon railroad system efficiency. The algorithm is also demonstrated by means of simulation studies for the Korean railroad lines now in service. A part of this novel algorithm includes the DC railroad powerflow algorithm that considers the mobility of railroad vehicles, which is necessary because the electric railroad system has a distinct distribution system where the location and power of vehicles are not fixed values. In order to derive a more accurate powerflow result, this algorithm has been designed to consider the rail voltage as well as the feeder voltage for calculating the vehicle voltage. By applying the resultant control scheme, the charging or discharging within a specific voltage boundary, energy savings and a substation voltage stabilization using storage devices are achieved at the same time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1791-1798
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• 2016

Recently, research about ESS(Emergency Support System) has been actively carried out to provide a variety of medical services using smart devices and wearable devices. Smart healthcare provides a personalized health care service using various types of bio-signal measuring sensors and smart devices. For the smart healthcare using a smart device, it is need to research about personal health monitoring using a smart wearable devices, and also need to research on service methods for first aid measures after an emergency. In this paper, we proposed about group management based emergency support system, that is monitoring about personal bio signal using smart devices and wearable devices to protect patient's life. The system notices to the medical volunteers based on the position information when an emergency situation. In addition, we have designed and implemented an emergency support system providing the information of the patient on the display when transmitting a picture of a patient using a smart device to the server.

• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.436-451
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• 2017

In primary and secondary schools, various information, such as grade results, observation and counseling materials, and psychological examination results which are generated in the course of educational activities, are accumulated and managed in various forms. Nevertheless, there is no educational information system that provides the analytical information for diagnosing and grasping students in a multidimensional manner. This is reminiscent of situations in which doctors rely solely on clinical experience to treat patients without using the results of various tests on patients. As pointed out by the Ministry of Education in 'Educational Big Data Utilization Measures' of the 5th Basic Plan of Educational Informatization(2014 ~ 2018), the reason why educational information systems do not exist is because there are no basic research as well as comprehensive and systemic research on this field. Therefore, this study aims to design and implement a prototype for educational information system that enables customized student guidance by introducing the concept of analytical information systems that are used in various fields. We defined the core functions and contents of educational information system through job analysis and focus group interview, and implemented the prototype using Naver ProtoNow.

• Journal of IKEEE
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• v.21 no.3
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• pp.195-201
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• 2017

High-power wireless transmission system becomes a key technology for the advance of battery-powered devices. The wireless power transfer devices are currently dominated by the inductive and capacitive wireless power transfer systems, which have relatively low power transmission capacity and low efficiency rather than the wired power transmission. The work presented in this paper proposes an alternative method of high-power transmission system, based on a variable speed motor system with a magnetic coupling. It enables high-capacity power transmission, high efficiency, and low possibility of failures, and the performance of the proposed scheme is verified by simulation and experiments.