• 한국철도학회논문집
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• 제10권6호
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• pp.717-722
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• 2007

본 논문에서는 직류 1500V 지하철 변전소의 가선전압과 피더별 전류량을 측정한 결과를 분석한다. 선릉과 양동시장 변전소들의 피더별 소비 및 회생전력을 측정하고, 피더별로 발생된 회생전력이 타 피더로 전달되는 전력량을 계산하였다. 전철변전소에서 회생전력이 교류될 수 있는 거리를 타 변전소와의 중간지점으로 가정하고, 전동차 1편성의 회생전력량을 기초로 변전소에서 발생되는 총 회생전력량을 근사식으로 계산하였다. 이렇게 얻어진 값과 측정된 피더간 교류된 회생전력량을 사용하여 변전소의 회생전력 실효전력량을 계산하고 회생인버터가 설치된 후 재활용할 수 있는 회생전력량을 근사적으로 얻었다.

• 한국산학기술학회논문지
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• 제9권2호
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• pp.333-338
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• 2008

본 논문에서는 유효한 DC 전압을 얻기 위해 요구되는 최소입력전압이 충분히 낮으면서도 소비전력이 기존의 정류기 보다 낮은 새로운 NMOS 전류미러형 브리지 정류기를 제안하였다. 설계된 정류기는 13.56 MHz의 HF (for ISO 18000-3)부터 915 MHz의 UHF (for ISO 18000-6) 및 2.45 GHz의 마이크로파 대역 (for ISO 18000-4)까지의 전 주파수 범위에 대해 RFID Transponder에 내장된 마이크로 칩을 구동하기에 충분히 높고 잘 정류된 직류전압을 공급할 수 있다. 제안된 NMOS 정류기의 출력특성은 고주파 등가회로를 이용하여 해석하였으며, 동작 주파수 종가에 따른 게이트 누설전류를 효과적으로 감소시킬 수 있는 회로적 방법을 이론적으로 제시하였다. 이러한 방법을 사용하여 설계된 NMOS 전류미러형 브리지 정류기는 3V 피크-투-피크 입력전압과 $45\;K{\Omega}$ 부하저항에서 $100\;{\mu}W$의 소비전력 특성과 2.13V의 DC 출력전압이 구해졌다. 제안된 NMOS 전류미러형 브리지 정류기는 기존의 정류기에 비해 UHF 및 마이크로파 대역에서도 안정적으로 동작하며, 보다 우수한 특성들을 보였다.

• 한국식품영양학회지
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• 제24권2호
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• pp.153-158
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• 2011

천연물로부터 lipase 저해물질을 개발하여 기능성 식품 산업에 응용하고자 lipase 저해 활성이 우수하여 전보에서 최종 선발된 도둑놈의 갈고리(Desmodium oxyphyllum DC.) 에탄올 추출물의 영양성분, 온도, pH 안정성과 생리기능성 등을 측정하였다. Lipase 저해물질을 함유한 도둑놈의 갈고리 에탄올 추출물의 지질과 단백질 함량은 각각 26.5%와 5.7%이었고 유리아미노산으로 asparagine과 tryptophan 함량이 각각 4,860 mg/건조중량 100 g, 1,209 mg/건조중량 100 g으로 물 추출물보다 높았다. 또한, 도둑놈 갈고리의 에탄올 추출물은 pH 3.0~9.0, $80^{\circ}C$ 이하에서 비교적 안정하였고, 이에 대한 생리 기능성을 측정한 결과, lipase 저해 활성은 74.2%, 항 치매성 Acetylcholinesterase 저해 활성은 68.4%로 비교적 높은 활성을 나타내었다.

• 한국인터넷방송통신학회논문지
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• 제21권4호
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• pp.135-141
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• 2021

산업자동화에 적합한 구형파 구동 BLDC 영구자석 전동기 설계 및 개발, 위치검출방식 회로와 드라이버 개발에 관심이 증가하고 있다. 그러나 이 전동기는 스위칭 손실에 의한 효율 저하 및 진동, 소음 등으로 인하여 가격적·기능적인 장점에도 불구하고 그 응용에 있어서는 다소 제한적인 실정이다. BLDC 모터를 설계하고 조립하는 과정에 있어 자기회로 설계의 문제 또는 조립과정상의 제품 불 균일 등으로 인하여 자극 각이 균일하지 않거나 자속분포가 왜현되는 문제가 발생하는데, 이러한 것들이 위치검출 어긋남의 원인이 되어 모터 특성을 악화시킨다. 또한 위치센서로부터 발생된 신호가 정확히 드라이버로 피드백 되어야만 정현파 구동 BLDC 시스템이 안정적으로 동작할 수 있다. 그러나 발생된 신호가 외부의 영향인 자속밀도 편차나 착자 기술에 의해 DC offset 성분이 발생하여 안정적인 위치검출을 할 수 없기에 본 연구에서는 DC offset 성분을 제거할 수 있는 제안된 회로를 연구하고자 한다.

• IEIE Transactions on Smart Processing and Computing
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• 제4권1호
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• pp.44-50
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• 2015

This paper presents a high speed synchronous single inductor dual output boost converter using Type-III compensation for power management in smart devices. Maintaining multiple outputs from a single inductor is becoming very important because of inductor the sizes. The uses of high switching frequency, inductor and capacitor sizes are reduced. Owing to synchronous rectification this kind of converter is suitable for SoC. The phase is controlled in time sharing manner for each output. The controller used here is Type-III, which ensures quick settling time and high stability. The outputs are stable within $58{\mu}s$. The simulation results show that the proposed scheme achieves a better overall performance. The input voltage is 1.8V, switching frequency is 5MHz, and the inductor used is 600nH. The output voltages and powers are 2.6V& 3.3V and 147mW &, 230mW respectively.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.518-522
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• 2001

In recent years, natural energy has attracted growing interest because of environmental concerns. Many studies have been focused on photovoltaic power generation systems because of the ease of use in urban areas. On the conventional system, many photovoltaic modules (PV modules) are connected in series in order to obtain the sufficient DC-bus voltage for generating AC output voltage at the inverter circuit. However, the total generation power on the PV modules sometimes decreases remarkably because of the shadows that partially cover the PV modules. In order to overcome this drawback, an AC module strategy is proposed. On this system, a small power DC-AC utility interactive inverter is mounted on each PV module individually and the inverter operates so as to generate the maximum power from the corresponding PV module. This paper presents a novel flyback-type utility interactive inverter circuit suitable for AC module systems. The feature of the proposed system are, (1) small in volume and light in weight, (2) stable AC current injection, (3) enabling a small DC capacitor. The effectiveness of the proposed system is clarified through the simulation and the experiments.

• Progress in Superconductivity
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• 제5권1호
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• pp.45-49
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• 2003

We have designed and fabricated the single-layer high $T_{c}$ SQUID magnetometer consisting of a directly coupled grain boundary junction SQUID with an inductance of 100 pH and 16 nested parallel pickup coils with the outermost dimension of 8.8 mm ${\times}$ 8.8 mm. The magnetometer was formed from a YBCO thin film deposited on an STO(100) bicrystal substrate with a misorientation angle of $30^{\circ}$. The SQUID magnetometer was further improved by optimizing the multi-loop pickup coil design for use in unshielded environments. Typical characteristics of the dc SQUID magnetometer had a modulation voltage of 40 $\mu\textrm{V}$ and a white noise of $30fT/Hz^{1}$2/. The SQUID magnetometer exhibited a 1/f noise level at 10 Hz reduced by a factor of about 3 compared with that of the conventional solid type pickup coil magnetometers and a very stable flux locked loop operation in magnetically disturbed environments.s.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.159-161
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• 2007

$CO_2$ laser sees that is most suitable to get this effect through minimum formation damage and advantage that is root enemy of effect that happen in minimum cellular tissue depth of 0.1mm is stable living body organization or internal organs institution. Formation damage by ten can be related in formation's kind or energy density, length of evaporation time. If shorten evaporation time, surroundings cellular thermal damage 200 - because happen within 400ums laser beam in rain focus sacred ground surroundings cellular tissue without vitiation me by evaporation Poe of very small floor as is clean steam can. Application is possible to vulva cuticle cousins by a paternal aunt quantity, uterine cancer, cuticle tumor by laser system that $CO_2$ laser gets into standard in obstetrics and gynecology application. Because effect that super pulse output is ten enemies of laser if uniformity one pulse durations are short almost is decreased, most of all pulse module special quality of pulse style $CO_2$ laser for obstetrics and gynecology mode stabilization by weight very, in this research to get into short pulse duration and higher frequency density, do switching by high frequency in DC-DC Converter output DC's ripple high frequency to be changed, high frequency done current ripple amount of condenser for output filter greatly reduce can. Ripple of output approximately to Zero realization applying possible inductor realization through a special quality experiment do.

• Journal of Advanced Marine Engineering and Technology
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• 제13권1호
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• pp.57-68
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• 1989

This paper treats the analytical and experimental studies on the improvement of commutating circuit for the speed control of DC motor. A simple circuit composed of R, L and C elements is proposed here for switching off power SCR carrying the load current. The real important in this chopper circuit is to determine the reasonable values of commutating circuit constants. In this paper, the reasonable values of the commutating circuit constants are basically determined on a view point of commutating performances in the given circuit model and must satisfy the following conditions. The first, the peak commutating current should be larger than the anticipated maximum load current. The second, the circuit turn-off time (tc) must be longer than the SCR turn-off time (tq). The third, the resistor should be enough large to permit the current to be neglected in the analysis of the commutation circuit, as well as be enough small to permit to charge the capacity voltage (Ec) to the half the value of source voltage (E) before the next communication cycle is initiated. The last, the period of chopping signal must be the least possible multiple of the damping vibration period of commutating circuit. The improved chopper circuit used in the experiment under unloaded condition was composed to meet the reasonable conditions mentioned above, and a successful commuting performance was achieved without failure. Several types of microprocessor having a different value of CPU speed individually have been applied to the experiment under the loaded conditions. Also it shows that the faster the speed of CPU is, the more stable the commutation turns out.

• 센서학회지
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• 제29권5호
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• pp.283-292
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• 2020

Current sensors that use a Hall element and Hall IC to measure the magnetic fields generated in steel silicon core gaps do not distinguish between direct and alternating currents. Thus, they are primarily used to measure direct current (DC) in industrial equipment. Although such sensors can measure the DC when installed in expensive equipment, ascertaining problems becomes difficult if the equipment is set up in an unexposed space. The control box is only opened during scheduled maintenance or when anomalies occur. Therefore, in this paper, a method is proposed for facilitating the safety management and maintenance of equipment when necessary, instead of waiting for anomalies or scheduled maintenance. A Bluetooth 4.0 low-energy current-sensor system based on near-field communication is used, which compensates for the nonlinearity of the current-sensor output signal using a piecewise linear model. The sensor is controlled using its generic attribute profile. Sensor nodes and cell phones used to check the signals obtained from the sensor at 50-A input currents showed an accuracy of ±1%, exhibiting linearity in all communications within the range of 0 to 50 A, with a stable output voltage for each communication segment.