• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.239-242
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• 1997

In this paper, the new filter that reduced output ripple to zero is proposed. This filter is composed of transformer and capacitor. The operating mode is verified with theoretical analysis of low ripple filter and computer simulation. DC-DC converter of input voltage DC 100[V], output 30[V]/30[A], switching frequency 20[KHz] is manufactured. In the result, computer simulation analysis is same to experimental result.

• 융합보안논문지
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• 제13권4호
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• pp.27-32
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• 2013

본 논문에서는 기저귀에 부착되어 배뇨를 감지한 후 10~20m 이내의 보호자 스마트폰으로 배뇨 발생을 자동으로 알리는 스마트폰형 배뇨알람장치의 구현 기술을 소개한다. 적용된 기술의 특징은 전력 소모 최소화에 있으며 이를 위해 저(低)전력 블루투스 v4.0 기술과 센서 데이터를 수집하지 않는 동안 센서 및 마이크로컨트롤러(micro-controller)를 수면(sleep) 모드로 동작시키는 전력 절감형 프로그램 구동 방식을 적용한다. 배뇨 발생의 정확도를 제고하기 위하여 온/습도 측정 데이터의 절대적인 값을 사용하지 않고 일정 시간 주기로 데이터를 측정하고 이전 값과 현재 값과의 차이를 기반으로 배뇨를 감지하는 방식을 적용한다. 적용 기술을 기반으로 시제품을 구성하고 제품의 성능 시험을 통해 최소 배뇨 검출량 100ml, 검출 정확률 90% 이상, 무선통신 성공률 100%의 성능이 제공됨을 확인한다.

• 한국통신학회논문지
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• 제32권11A호
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• pp.1113-1119
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• 2007

본 논문에서는 IEEE 802.16e의 절전클래스 I에 대하여 초기 수면 윈도우 크기와 수면 모드 내에서의 수면 윈도우 크기를 결정하기 위한 다양한 가능성 있는 방법론들을 제시하고, 이들 방법론들이 전력 절약 성능에 어떠한 영향을 주는지를 비교 분석하였다. 비교 대상인 방법론들은 IEEE 802.16e에서 제시하는 EICV 방법과 대안으로서 고려할 수 있는 EIED, EILD, LIED, LILD 방법들이다. 실험 결과는 EICV보다 LILD, EIED 방법론이 더 나은 성능을 보여주고 있다. 특히, 트래픽의 양이 많은 경우에는 EIED 방법이 더 낫고, 트래픽의 양이 적은 경우에는 LILD 방법이 더 나은 것으로 분석되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1511-1514
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• 2002

This paper presents design and construct of flat type step-down piezoelectric transformer for the application to AC adaptor. This piezoelectric transformer operated in resonance vibration mode. In this paper, finite element method(FEM) was used for analysing piezoelectric transformers. Stress and electric field of the transformer were simulated at resonance frequency. Using this simulation results, we manufactured improved Rosen type piezoelecric transfomer and measured its output characteristics. As results, output power was linearly increased by increasing input power at resonance frequency and it was found that the transformer an invariable output power for input power. From these results, we expect that this piezoelecric transfomer can be applied to small size and low capacitive AC adaptor.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2134-2143
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• 2018

This work introduces a fault diagnosis method for transformer based on self-powered radio frequency identification (RFID) sensor tag and improved Hilbert-Huang transform (HHT). Consisted by RFID tag chip, power management circuit, MCU and accelerometer, the developed RFID sensor tag is used to acquire and wirelessly transmit the vibration signal. A customized power management including solar panel, low dropout (LDO) voltage regulator, supercapacitor and corresponding charging circuit is presented to guarantee constant DC power for the sensor tag. An improved band restricted empirical mode decomposition (BREMD) which is optimized by quantum-behaved particle swarm optimization (QPSO) algorithm is proposed to deal with the raw vibration signal. Compared with traditional methods, this improved BREMD method shows great superiority in reducing mode aliasing. Then, a promising fault diagnosis approach on the basis of Hilbert marginal spectrum variations is brought up. The measured results show that the presented power management circuit can generate 2.5V DC voltage for the rest of the sensor tag. The developed sensor tag can achieve a reliable communication distance of 17.8m in the test environment. Furthermore, the measurement results indicate the promising performance of fault diagnosis for transformer.

• 한국표면공학회지
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• 제45권2호
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• pp.53-60
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• 2012

Modulated Pulse Power (MPP) magnetron sputtering is a new high-power pulsed magnetron sputtering (HPPMS) technology which overcomes the low deposition rate problem by modulating the pulse voltage shape, amplitude, and the duration. Highly ionized magnetron sputtering can be performed without arcing because it can be controlled as multiple steps of micro pulses within one overall pulse period in the range of 500-3,000 ${\mu}s$. In this study, the various waveforms of discharge voltage and current for micro pulse sets of MPP were investigated to find the possibility of controlling the strongly ionized plasma mode. Enhanced ionization of the sputtered metal atoms was obtained by OES. Large grained columnar structure can be grown by the strongly ionized plasma mode in the AZO deposition using MPP. In the most highly ionized deposition condition, the preferred orientation of (002) plane decreased, and the resistivity, therefore, increased by the plasma damage.

• 전력전자학회논문지
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• 제24권4호
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• pp.279-285
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• 2019

This study proposes an enhanced switching pattern that can improve energy transfer efficiency in an active cell-balancing circuit using a multiwinding transformer. This balancing circuit performs cell balancing by transferring energy stored in a specific cell with high energy to another cell containing low energy through a multiwinding transformer. The circuit operates in flyback and buck-boost modes in accordance with the energy transfer path. In the conventional flyback mode, the leakage inductance of the transformer and the stray inductance component of winding can transfer energy to an undesired path during the balancing operation. This case results in cell imbalance during the cell-balancing process, which reduces the energy transfer efficiency. An enhanced switching pattern that can effectively perform cell balancing by minimizing the amount of energy transferred to the nontarget cells due to the leakage inductance components in the flyback mode is proposed. Energy transfer efficiency and balancing speed can be significantly improved using the proposed switching pattern compared with that using the conventional switching pattern. The performance improvements are verified by experiments using a 1 W prototype cell-balancing circuit.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.152-161
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• 2022

We analyzed mitigation strategies for steam generator tube rupture (SGTR) accidents using MARS code under both full-power and low-power and shutdown (LPSD) conditions. In general, there are two approaches to mitigating SGTR accidents: supplementing the reactor coolant inventory using safety injection systems and depressurizing the reactor coolant system (RCS) by cooling it down using the intact steam generator. These mitigation strategies were compared from the viewpoint of break flow from the ruptured steam generator tube, the core integrity, and the possibility of the main steam safety valves opening, which is associated with the potential release of radiation. The "cooldown strategy" is recommended for break flow control, whereas the "RCS make-up strategy" is better for RCS inventory control. Under full power, neither mitigation strategy made a significant difference except for on the break flow while, in LPSD modes, the RCS cooldown strategy resulted in lower break and discharge flows, and thus less radiation release. As a result, using the cooldown strategy for an SGTR under LPSD conditions is recommended. These results can be used as a fundamental guide for mitigation strategies for SGTR accidents according to the operational mode.

• 대한전자공학회논문지
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• 제15권3호
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• pp.24-29
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• 1978

사이크로트론파와 전자속파의 결합에 의한 신형모드의 동작이 관찰되었다. 전파형성 과정을 분석하는 데 전자동력학과 결합모드에 의한 방법이 적용되었으며 유도된 이론적 이득식에서 신형초고주파 증폭기가 설계 제작 되었으며 실험결과잡음이 없이 고전력을 얻을 수 있는 증폭기임이 보여진다.

• 전자공학회논문지A
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• 제33A권11호
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• pp.52-59
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• 1996

This paper presents a monopulse feed structure with low sidelobe monopulse pattern, which consists of a E-plane corrugated horn and a unfiorm pick-up aperture power divider. Tfhe design methods and epxerimental resutls of the E-plane corrugated feeder are described. Modified hybrid mode analysis and GSM (generalized scattering matrix) methods are introduced to design the E-plane corrugated feed horns. The 24-port corrugated feeder is designed using modified hybrid mode analysis initially and verified using GSM methods. Measurement results show that this feeder has low return loss and sidelobe level at sum and difference channel, respectively.