• IE interfaces
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• v.25 no.2
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• pp.153-162
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• 2012

The reliability is defined as a probability that a system will operate properly for a specified period of time under the design operating conditions without failure and it has been considered as one of the major design parameters in the field of industries. Reliability-Redundancy Optimization Problem(RROP) involves selec tion of components with multiple choices and redundancy levels for maximizing system reliability with constraints such as cost, weight, etc. However, in practice both active and cold standby redundancies may be used within a particular system design. Therefore, a redundancy strategy(active, cold standby) for each subsystem in order to maximize system reliability is considered in this study. Due to the nature of RROP, i.e. NP-hard problem, A Parallel Particle Swarm Optimization(PPSO) algorithm is proposed to solve the mathematical programming model and it gives consistently better quality solutions than existing studies for benchmark problems.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.4
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• pp.555-570
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• 1995

We consider a preventive replacement policy for a cold-standby system with N components, in which only one component is in operation at a time. If the component in operation fails, a standby component is immediately switched into operation. If all components fail, the system fails. The system is inspected at random poins in time to determine whether it is to be replaced or not. If the number of failed components at the time of inspection exceeds a threshold value r, the system is replaced. Otherwise the decision is put off until the next inspection point arrives. Under the cost structure which includes a replacement cost, a system down-time cost and a holding cost of the components, we develop an efficient procedure to find the optimal control values N and r, which minimize the expected cost per unit time.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.169-174
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• 2023

Currently, overall power usage is also increasing as power demand such as homes, offices, and factories increases. The increase in power use also raised interest in standby power as a change in awareness of energy saving appeared. Home and office devices are consuming power even in standby conditions. Accordingly, there is a growing need to reduce standby power, and it aims to have standby power of 1W or less. An intelligent outlet uses a near-field wireless network to connect to a home network and cut or reduce standby power of a lamp or appliance connected to an outlet. This research aims to develop a monitoring system and an intelligent outlet that can remotely monitor the amount of electricity used in a lighting lamp or a home appliance connected to an outlet using a short-range wireless network (Zigbee). Also, The intelligent outlet and monitoring system developed makes it possible for a user to easily cut off standby power by using a portable device. Intelligent outlets will not only reduce standby power but also be applicable to fire prevention systems. Devices that cut off standby power include intelligent outlets and standby power cutoff switches, so they will prevent short circuits and fires.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.81-86
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• 2003

Using DG for peak-shaving unit could reduce the overall system operating cost, and using DG for standby power unit could improve the reliability of the distribution system The models of peak-shaving unit and standby power unit are different from each other. The Monte-Carlo simulation is suitable for the purpose of the analysis of two DG models. In this paper, the reliability indices are calculated from the time-sequential method, and the merit and defect of the peak-shaving unit and standby power unit are investigated.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.1
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• pp.1-8
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• 2010

This paper presents the self-oscillating flyback converter for reducing standby power without a control-IC. The proposed self-oscillating flyback converter includes a DC-Blocking capacitor for reducing constant power loss of initial switching path of a conventional self-oscillating flyback converter. it's possible to reduce the standby power to 1W and power efficiency. To confirm the validity of proposed system, comparison of conventional system, verification of experimental results is presented by realization of 35W power system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.5
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• pp.616-622
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• 2020

Recently, as the interest in power saving increases with the development of IoT technology, research on power saving of smart devices, which are being miniaturized, is being actively conducted. In particular, due to the diversification of IoT-based smart devices and the increase in personal penetration rate, the issue of standby power even when not in use is increasing. However, there is a drawback of physically unplugging the outlet or turning off the power in order to substantially reduce standby power. Since Zigbee is used instead of the existing IP, it is necessary to change to the IoT standard protocol based on the Internet network. Therefore, this paper designed and implemented the standby power saving system applying CoAP, the IoT standard protocol, to the existing Zigbee technology. Existing systems and evaluations confirmed that the average standby power of about 8.4Wh was reduced.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.267-270
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• 2000

In this paper, we consider the simple redundant structures with the function of hardware based active/standby control. The system includes two switch modules. The switch module is connected to a data bus, but only the active switch module has control of the data bus. The standby unit takes over the function of the active unit when the active unit failure or mode command are asserted. And this paper illustrate the high-speed router system and the overall redundant system architecture. The proposed redundant architecture for 80G Router system is verified and implemented with experiment.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.439-445
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• 2005

This paper is to investigate the approximate confidence limits of the reliability performances (such as failure rate, reliability function and average life) for a cold standby series system. The Bayesian approximate upper confidence limit of failure rate is obtained firstly, and next Bayesian approximate lower confidence limits for reliability function and average life are presented. The expressions for calculating Bayesian lower confidence limits of the reliability function and average life are also obtained, and an illustrative example is examined numerically by means of the Monte-Carlo simulation. Finally, the accuracy of confidence limits is discussed.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.8
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• pp.457-462
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• 2003

This paper presents an optimal operating strategy of distributed generation (DG) with reliability worth evaluation of distribution systems. Using DG for peak-shaving unit could reduce the overall system operating cost, and using DG for standby power unit could reduce the customer interruption cost. If DG operating cost is less than utility power cost in peak time, DG should be running to reduce the overall system operating cost. When customer interruption cost enlarges, however, standby power strategy may be the better operating strategy than peak-shaving strategy. Selection of whether DG should be operated for peak-shaving or for standby power, needs the accurate reliability worth evaluation and the accurate power cost evaluation. Instead of using annual average reliability worth, the concept of hourly reliability worth is introduced in this paper to determine the optimal operating decision of DG. Applying suggested hourly reliability worth, the distribution companies that possess DG could set up the optimal operating strategy of DG.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.636-645
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• 2006

In order to use railway system standby power, produced 160Ah NiMH battery that would be able to substitute the lead acid battery or NiCd battery form which contain the toxic material in environment, using parallel connected 80Ah NiMH battery. And in order to develop proper electrode in the 160Ah NiMH battery, tested high rate discharge performance of the ternary electrolyte. 160Ah NiMH battery evaluated the various test in order to use railway system standby power.