• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1019-1022
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• 2003

This paper has proposed a 4- bit 20MHz Flash A/D converter design available analog signal processing and realized its intergrated circuit. The parallel comparison method A/D converter quantized analog signals swiftly using various converters. Also this theme has designed economic power dissipation circuit using a preamplifier of low volt & power CMOS comparator. Also the system was fabricated by Hynix 0.35um CMOS process.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.603-605
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• 2006

To reduce inference of any power delivery failures in underground power cable, power system operators are trying to find effective way of finding fault location as soon as possible. But it is very difficult to find fault location exactly for underground power cable. We are developing fault location system for underground power cable which can detect its fault location exactly. This new system monitors current and voltage of underground power cable by using low voltage and current sensors and if there are any accidents, it records its transient signal. Fault location is calculated by analyzing recorded signal. To develop fault location system for power cable, we needed fault simulation system and we installed it physically and tested. In this rapers, we describe on describe of fault location system for underground power cable.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.549-551
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• 2005

Bidirectional DC/DC converters allows transfer of power between two dc sources, in either direction. Due to their ability to reverse the direction of flow of power, they are being increasingly used in many applications such as battery charger/dischargers, dc uninterruptible power supplies, electrical vehicle motor drives, aerospace power systems, telecom power supplies, etc. This paper proposes a new bidirectional Sepic/zeta converter. It has low swicthing loss and low conduction loss due to auxiliary communicated circuit and synchronous rectifier operation, respectively. Because of positive and buck/boost-like DC voltage transfer function(M=D/1-D), the proposed converter is very desirable for use in distributed power system . The proposed converter also has both transformerless version and transformer one.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.961-963
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• 2000

Most of the application standard of the low-voltage devices have applied one the IEC standard another the UL standard. European union applied the IEC60947-1 standard has not exceed 1000V a.c. or 1500V d.c.. Therefore. it is necessary to the low-voltage device has expended for rated operational voltage with our products. The export of European market shall be made for the CE-Marking in accordance with IEC60947-1 ( Low-voltage switchgear and controlgear). We shall be considered for the requirement with the IEC standard. In this time to study for power supply system at EU ( European union. At that time for design and development in order to the construction and test method among the study for the rated insulation voltage at less then 690V.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1712-1724
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• 2024

Spiral tubes are used in a wide range of applications and it is significant to understand the vibration introduced by two-phase flow in spiral tubes. In this paper, the numerical method is used to study the vibration induced by the gas-liquid two-phase flow in a spiral tube with different flow regimes. The pressure fluctuation characteristics at the pipe wall and the solid vibration response characteristics are obtained. The results show that the motion of small bubbles in bubbly flow leads to small pressure fluctuations with low-frequency broadband (0-50 Hz). The motion of the gas plug in the plug flow causes small amplitude periodic pressure fluctuation with a shortened low-frequency broadband (0-15 Hz) compared to the bubbly flow. The motion of the gas slug in the slug flow causes large periodic fluctuations in pressure with a significant dominant frequency (6-7 Hz). The wavy flow is very stable and has a distinct main frequency (1-2 Hz). The vibration regime in the bubbly flow and wave flow are close to the first-order mode, and the vertical vibrating component is dominant. The plug flow and slug flow excite higher-order vibration modes, and the lateral vibration component plays more important part in the vibration response.

• ETRI Journal
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• v.32 no.6
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• pp.940-949
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• 2010

Rack-level DC power supply is the optimal technology for providing DC power to a volume server without any power infrastructure changes in an existing AC data center. In this paper, we propose a smartly controllable and monitorable DC rack power system. The proposed system improves power efficiency by changing the power distribution architecture of a conventional method in the rack. We developed an optimal power control method in multipower modules to provide high efficiency at low loads. In addition, the proposed system provides real-time web monitoring of the rack power and environment around a rack. In our experiments, the proposed system improved the power efficiency by over 10% compared to an AC power system providing N+1 redundant power and power monitoring.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.90-94
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• 2013

A low loss power dividing switch in a indoor microwave power distribution system is proposed and designed with a various power dividing ratio. Switching characteristics are analyzed by use of the S-parameter of the switch. Newly proposed switch showed a very low return loss less than -30dB at the operating frequency of 2.45GHz. Three kinds of the switch in which we take out individually 1/2, 1/3 and 1/4 of the input power were fabricated, and measured the delivered, transmitted, and return loss power ratio. Simulated results showed that the lower power ratio is, the better accurate operating performance shows. This switch can switch the input power from 4.5% to 58% with the variance of 5% output power. The experimental results are in good agreement with the simulation within the return loss of 1%.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.85-95
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• 2004

As the design complexity increases, it is a major problem that the size of test pattern is large and power consumption is high in scan, especially system-on-a-chip(SoC), with the automatic test equipment(ATE). Because static compaction of test patterns heads to higher power for testing, it is very hard to reduce the test pattern volume for low power testing. This paper proposes an efficient compression/decompression algorithm based on run-length coding for reducing the amount of test data for low power testing that must be stored on a tester and be transferred to SoC. The experimental results show that the new algorithm is very efficient by reducing the memory space for test patterns and the hardware overhead for the decoder.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.4
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• pp.248-254
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• 2013

The size and power consumption of digital circuits including the dimming circuit part will increase for high-performance solid state lighting (SSL) systems in the future. This study examined the low-power consumption of adiabatic dynamic CMOS logic (ADCL) due to the principles of adiabatic charging. Furthermore, the designed low-power ADCL digital pulse width modulation (PWM) was optimized for SSL dimming systems. For this purpose, an ADCL digital 3-bit PWM was optimized in two steps. In the first step, the architecture of the ADCL digital 3-bit PWM was miniaturized. In the second step, the clock cut-off circuit was designed and added to the ADCL PWM. As a result, compared to the original configuration, 60 transistors and 15 capacitors of ADCL digital 3-bit PWM were reduced for miniaturization. Moreover, the clock cut-off circuit, which controls wake-up and sleep mode of ADCL D-FFs, was designed. The power consumption of an optimized ADCL digital PWM for all bit patterns decreased by 54 %.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.503-505
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• 2008

Photovoltaic(PV) resource connected in the power system can be affect to the power quality. To analyze the power quality, this paper simulate the variation of power factor by PV resource connected to the low voltage system. The power factor calculator and full-bridge inverter of PV system are modeled by EMTP/MODELS. Simulation results according to the PV capacity and load are presented.