• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.85-88
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• 2000

Distributed Control System(DCS) is one of the best solutions to implement control systems because it provides continuous observation of control process and execution of commands to induce proper operations. In this paper, a design of control network for DCS in nuclear power plant is proposed. The proposed control network on DCS has a simple architecture and deterministic property. Thus, the proposed control network offers hard real-time periodic service. It also has redundant media for the fault-tolerance. As a result, high safety and reliability required in nuclear power plant are guaranteed.

• Journal of Power Electronics
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• v.2 no.3
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• pp.199-205
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• 2002

This paper compares three kinds of soft-switching circuits from viewpoints of surge suppression, load characteristic, and power efficiency for a tapped-inductor buck converter with low voltage and high current. As a result, these soft-switching techniques have achieved much higher efficiency of 80 % when compared with a hard-switching buck converter for the output condition of 1V and 20A.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.6
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• pp.451-462
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• 2009

Recently, there are many active studies to enhance low I/O performance of hard disk device. The studies on the hardware make good progress whereas those of the system software to enhance I/O performance may not support the hardware performance due to its poor progress. In this paper, we propose a new method of prefetching n-blocks into the flash memory. The proposed method consists of three steps: (1)analyzing the pattern of read requests in block units; (2)determining the number of blocks prefetched to flash memory; (3)replacing blocks according to block replacement policy. The proposed method can reduce the latency time of hard disk and optimize the power consumption of the computer system. Experimental results show that the proposed dynamic n-block method provides better average response time than that of the existing AMP(Adaptive multi stream prefetching) method by 9.05% and reduces the average power consumption than that of the existing AMP method by 11.11%.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.1
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• pp.30-40
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• 2010

The hard disk is one of the most frequently used storage in IPTV sep-top box. It has large storage capacity and provides fast I/O speed compared to its price whereas it causes high power consumption due to mechanical characteristics of spindle motor. In order to play streaming data in the set-top box, spindle motor of hard disk keeps active mode and it causes high power consumption. In this paper, We propose an offset-buffering and multi-mode spin-down method to reduce power consumption for streaming data playback. The offset-buffering inspects the user's viewing pattern and performs buffering based on the analysis of viewing pattern. So, it can maintain the status of spindle motor as idle mode for long time. Besides, it can reduce power consumption by spinning down according to offset-buffer size. The experimental result shows that proposed offset-buffering and multi mode spin-down method is about 28.3% and 12.5% lower than the full-Buffering method in terms of the power consumption and spin-down frequency, respectively.

• Journal of Power Electronics
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• v.12 no.3
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• pp.418-428
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• 2012

It is very important to improve the overall efficiency of systems with a source of power that has low-voltage high-current terminal characteristics such as fuel cells. A resonant converter is required for high efficiency systems. However, the peak value of the switches current is large in a resonant converter. This peak current requires a large number of switches and results in system failures. In this paper, an analysis and experiments of a resonant isolation push-pull converter are performed. A switching loss analysis is performed in order to compare losses between a resonant push pull converter and a hard switching push-pull converter. Specially, the conduction loss is studied based on the ratio between the resonant frequency and the switching frequency. In addition, a method for improving the efficiency is implemented with conventional HF insolation converters.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.575-580
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• 1998

A power meter is an instrument for measuring in watts the power flowing in a electric equipment. Since the value which a conventional power meter measures is analog, the power meter is hard to determine a phase difference between the voltage and current for a inductive load. The phase difference causes a loss of electric power and a increase of power-line load. In this paper, we propose a digital power meter using TI's DSP(Digital Singnal Processor) TMS320C5x, which is employed to calculate the phase difference and more accurate power consumption.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.279-282
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• 2005

Recently, due to the launching of digital broadcasting service, a demand of PDP TV with large screen size is sharply rising. PDP power module is mainly divided into power factor correction (PFC) stage and sustaining power stage. Especially, sustaining power module has pulsating load characteristics. So, the hard switching at light load condition causes low efficiency and thermal problem. Therefore, a new power conversion circuit for sustaining power module of 60' PDP is proposed whose ZVS is obtained by additional ZVS tank. This paper presents properties of the proposed converter through mode analysis, numerical analysis. And a 900w prototype for sustaining power module of 60' PDP is produced to verify the analytic results. As an experimental results, ZVS is achieved from full load to 10% load variation and more than 92% of high efficiency is obtained at 10% load condition.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.5
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• pp.45-52
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• 2015

The read performance of hybrid hard disk is better than the legacy hard disk and power consumption is also considerably low. As blocks with enough localities may be located in the non-volatile cache whose size is generally limited, an effective block replacement scheme is required. As this replacement is inevitably affected by various parameters, we define this issue as a kind of multiple criteria decision model. To solve this problem, this paper suggests a new block replacement algorithm based on the analytic hierarchy process. Through simulation for our model, we confirmed that the proposed model could be used as a replacement algorithm of the hybrid hard disk as it may improve boot time as well as response time of general applications.

• Journal of Power Electronics
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• v.9 no.1
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• pp.18-25
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• 2009

Conventional series-resonant pulse frequency modulation controlled DC-DC high power converters with a high-frequency transformer link which is designed for driving the high power microwave generator has the problem of hard switching commutation at turn-on and turn-off of active power switching devices. This problem is due to the influence of the magnetizing current of the high-frequency transformer. This paper presents a novel prototype for a high-frequency transformer using parasitic parameters with a lossless inductive snubber and a series resonant capacitor assisted series-resonant zero current switching pulse frequency modulated DC-DC power converter, which is designed using a high power magnetron for microwave ovens. In order to implement a complete and efficient soft switching commutation, the performance of the new converter topology is practically confirmed and evaluated in the prototype of a power microwave generator.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.477-483
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• 2011

Existing switching system that is one of the ways which are used for DC/DC power converter is classified to hard-switching system and resonant-soft-switching system, generally. Hard-switching system is inefficient because the power loss of the switching element is large when it is been to trun on or turn off. And resonant-soft-switching system have the defect that need to add the another reactor and capacitor that make it expensive and huge. This paper suggest the ZVS Full-Bridge power converter contrcution of novel switching system for the overcoming these shortcomings. In Suggested soft-switching system, the front of buck converter at diode current, switch is changing on and off at the part of full-bridge converter's zero voltage part. as the result that is possible to be ZVS excepting the reactor and capacitor. also to verify the reasonability of the isolated ZVS full-bridge DC/DC converter as previously suggested, we produced the 500[W] level DC/DC converter and enforced the simulation for Psim, and then it able to conform the superiority of the DC/DC converter's efficient.