• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.79.2-79.2
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• 2010

FCEV(Fuel Cell Electric Vehicle)는 연료전지스택의 각 셀에서 반응하는 화학에너지를 전기에너지로 변환하여 차량을 구동하는 시스템이다. 이러한 연료전지 셀이 정상적인 발전이 되지 않을 경우 비정상적인 전압이 발전되고 이것을 방치한다면 연료전지 스택의 영구적인 고장을 야기할 수 있다. 이를 방지하기 위해 SVM(Stack Voltage monitor) 제어기는 각 셀의 전압을 측정하고 그 정보를 상위 제어기인 FCU(Fuel cell Control Unit)에 전달한다. 이에 FCU는 연료전지스택의 고장을 운전자에게 알리고 연료전지스택의 발전을 멈추게 한다. 기존에 SVM 제어기는 각 셀마다 분압저항을 통하여 측정하며 이 전압의 차를 이용하여 셀 전압을 계산하는 방식이었다. 이는 상위 셀로 갈수록 오차가 커지는 문제가 있고 다수의 CPU 및 DC/DC 컨버터가 적용이 필요하여 복잡한 구성과 가격이 높은 문제가 있었다. 이러한 문제점을 해결하기 위하여 cell monitoring IC를 적용하였고 좀 더 정밀한 측정과 간단한 인터페이스를 구성할 수 있었다. 본 연구에서는 기존 SVM 제어기보다 안정되고 정밀한 SVM 제어기의 개발에 대해 기술하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.228-231
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• 2015

Recently, the electric power consumption concentrated in specific seasons and time causes the unstable power supply. To resolve this problem, smart grid has emerged as an alternative to consume the power, efficiently. Smart grid that combines ICT with the existing electrical grid includes demand response as a core technology. Demand response enable the power consumption effectively by offering a variety of informations, such as power consumption, charges expected, etc., for consumers who voluntarily participate in the electricity markets. In this paper, we design the automatic demand response systems based on SEP 2.0 for the efficient power control of home appliances in the smart grid environments.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.584-591
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• 2004

The conventional analog-based firing circuit can be implemented by comparing a linearly decreasing periodic sawtooth waveform synchronized to the ac supply, with a control signal corresponding to the desired converter delay angle. This circuit requires a large number of passive components (resistance and capacitor) and careful adjustment of the synchronization circuity. In this paper a novel firing circuit is proposed for thyristor switch. The proposed circuit is implemented by using digital components(FPGA, A/D, and DSP etc.) on the basis of the analog cosine method.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.11
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• pp.1081-1087
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• 2015

This article aims to provide a design method of warning thresholds for active safety systems based on the performance-based approach considering driver behaviors. Both positive and negative consequences of warnings are considered, and the main idea is to choose a warning threshold where the positive consequence is maximized, whereas the negative consequence is minimized. The process of the performance-based approach involves: Defining the operating scenarios; setting the trajectory models, including human characteristics; estimating the alert and nominal trajectories; estimating the performance metrics; generating a performance-metric plot; and determining the alert thresholds. This paper chose a lane-departure warning system as an example to show the usefulness of the performance-based approach. Both human and sensor characteristics were considered in the system design, and this paper provided a quantitative method to include human factors in designing active safety systems.

• Korean Journal of Cognitive Science
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• v.6 no.2
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• pp.81-95
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• 1995

Intelligent courseware predicts the status of student diagnosing student diagnosing student's response and performs an adaptive tutoring based on the student model.This paper designs an authoring tool that supports dyanmic sequence control of tutoring.And also it defines a lesson description language for the dynamic control sequence.Using this language we can represent a control sequence of courseware statically and dynamically.We apply the proposed tool for controlling sequence of C language courseware and show the usability of the proposed system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.356-363
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• 2002

Transactions in real-time active databases have the notion of activeness where transactions are generated by external effects and another transaction. In this paper, we improve the real -time active concurrency control algorithm by applying Thomas' write rule and considering relationship between transactions fired by active rules. We also present the experimental results of our algorithm comparing other real-time active concurrency control algorithms. The experimental results show that our algorithm has superior performance with respect to the raio of transactions satisfying deadline.

• Journal of Korean Society of Transportation
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• v.29 no.6
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• pp.129-136
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• 2011

Variable Message Signs have been used for providing information on the current traffic conditions. However, it is considered more important to achieve optimal traffic allocation among the alternative routes by strategic VMS information provision. Fuzzy control is very effective and efficient to deal with such systems that are too complex and uncertain to build mathematical models. In this paper, a fuzzy feedback controller for VMS is proposed, whose goal is to achieve the travel time equilibrium between the two alternative routes. The performance of the suggested controller is implemented and examined using MATLAB/Simulink. More robust controller applicable to a real highway network is suggested for the further research.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.3
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• pp.517-524
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• 2018

This Paper presents the real time things control method through Web browser that has no limited by time and place. To design and realize the system that not only makes it possible to communicate with other protocols but also reinforces the advantages of each protocol, the real time communication environment, based on the WebSocket technology of HTML5 whose international standardization has recently been completed, is realized. Also, the message communication environment in the low electricity and limited communication environment is realized using MQTT(Message Queue Telemetry Transport) protocol which is in the spotlight as the optimum protocol in the IoT environment. And by designing intuitive and simple hardware and realizing the responsive web interface which is not limited by the user's contact devices, the interactive system in which the user receives real time data from the hardware and reversely the user controls the things is designed and realized.

• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.141-153
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• 2014

Droplet based microfluidic systems have been developed for the application of biological and chemical research field. A picoliter droplet in microfluidic device provides a compartmentalized and well-defined reactor in miniaturized system. The microfluidic system with small droplets can reduce reagent cost and enhance efficiency through automated high-throughput screening system. In this review, we summarize the functionality of droplet based microfluidic system including droplet generation, precise droplet control, and various applications. In addition, this article reviews current applications in chemistry and biology, and discuss advantages of droplet based microfluidics compared with conventional manner.

• The Journal of the Korea Contents Association
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• v.5 no.1
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• pp.19-26
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• 2005

This paper introduces a new design method of realizing the machine control interface by using bio-signals(EEG/EOG). This method can be further expanded to be applied to the computer system responding to EEG or EOG signals and the general bio-feedback system. For this reason, we made the remotely controlled toy system controlled by the EEG spectrums, their combination indexes, and EOG parameters. And the headset that has bio-signal processing modules built-in offers convenience for users, and this make much more advanced system than any other existing BCI and BMI system.