• 설비공학논문집
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• 제24권8호
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• pp.605-611
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• 2012

The objective of this study is to investigate the influence of the cooling performance for a water-to-water 10 RT ground source heat pump by using the water switching and refrigerant switching method. The test of water-to-water ground source heat pump was measured by varying the compressor speed, load side inlet temperature, and ground heat source side temperature. The cooling capacity and refrigerant mass flow rate of the heat pump increased with increasing ground heat source temperature. But COP of the heat pump decreased with increasing ground heat source temperature. As a result, the water switching method with counter flow, compared to a refrigerant switching method, improves the cooling capacity and COP by approximately 6~9% in average, respectively.

• 한국지열·수열에너지학회논문집
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• 제8권2호
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• pp.9-15
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• 2012

The objective of this study is to investigate the influence on the heating performance for a water-to-water 10RT ground source heat pump by using the water switching and refrigerant switching method. The test of water-to-water ground source heat pump was measured by varying the compressor speed, load side inlet temperature, and ground heat source side temperature. The heating capacity and COP of the heat pump increased with increasing ground heat source temperature. As a result, compared to a refrigerant switching method, the water switching method with counter flow improves the heating capacity and COP by approximately 5% in average, respectively.

• Journal of Photoscience
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• 제9권2호
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• pp.317-319
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• 2002

All-optical switching has been demonstrated in bacteriorhodopsin (bR) based on nonlinear intensity induced excited state absorption. The transmission of a cw probe laser beam at 410 nm corresponding to the peak absorption of M state through a bR film is switched by a pulsed pump laser beam at 570 nm that corresponds to the maximum initial 8 state absorption. The switching characteristics have been analyzed using the rate equation approach considering all the six intermediate states (B, K, L, M, N and 0) in the bR photocycle. The switching characteristics are shown to be sensitive to life time of the M state, absorption cross-section of the 8 state at probe wavelength ($\sigma$ $\_$Bp/) and peak pump intensity. It has been shown that the probe laser beam can be completely switched off (100 % modulation) by the pump laser beam at relatively low pump powers, for $\sigma$$\_$Bp/ = O. The switching characteristics have been used to design all-optical NOT, OR, AND and the universal NOR and NAND logic gates for optical computing with two pulsed pump laser beams.

• 한국정보통신학회논문지
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• 제2권2호
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• pp.267-273
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• 1998

본 논문에서는 charge pump 회로를 차동 전류 스위치 구조를 갖는 회로를 사용하여 설계하였다. charge pump 회로의 스위칭 속도를 향상시키기 위하여 CMOS 보다 스위칭 속도가 빠른 MESFET를 이용하여 회로를 설계하였다. 차동 전류 스위치 구조의 charge pump회로가 고주파수 대역에서 동작하는데 따른 회로의 성능 및 안정성 문제를 제시하고 분석하였다. 또한 charge pump 회로의 성능을 평가하기 위한 척도를 세부적으로 정의함으로써 charge pump의 성능을 표현하게 된다. 설계된 회로는 HSPICE 시뮬레이터를 사용하여 시뮬레이션 하였으며, 시뮬레이션 결과 본 논문에서 제시한 구조가 1GHz급의 charge pump 회로로 설계가 가능하다는 것을 알 수 있었다.

• 대한전자공학회논문지SD
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• 제45권5호
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• pp.50-57
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• 2008

본 논문에서는 CMOS image sensor(CIS)에서 사용될 수 있는 고 효율 charge pump를 제안하였다. 제안된 charge pump는 CIS의 동작 특성을 활용하여 switching loss 및 reversion loss를 최소화하여 고 효율 동작을 실현하였다. 즉, CIS 픽셀 동작 구간에 따라 local clock driver, 펌핑 커패시터, 그리고 charge 전달 switch의 크기를 역동적으로 조절함으로써 switching loss 를 최소화하였다. 또한, schmitt trigger를 채용한 tri-state local clock driver를 이용하여 non-overlapping 구간이 충분히 확보된 local clock을 공급할 수 있게 함으로써 reversion loss를 최소화하였다. 0.13-um CMOS 공정을 이용한 시뮬레이션 비교 결과, 제안된 charge pump는 구동 전류가 없는 조건에서 기존 구조에 비해 최대 49.1% 전력 소모를 개선하였으며, 구동 전류가 최대인 조건에서는 19.0% 전력 소모를 개선할 수 있었음을 확인하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.208-210
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• 2007

This paper proposes a novel direct instantaneous pressure control(DIPC) of hydraulic pump system with SR drive. And it has very simple control structure, because it doesn’t use any speed and torque control for adjusting pump pressure. The hysteresis band of pressure and proper switching rules can make the actual pump pressure to be constant with fast dynamic response. Therefore, the proposed DIPC method can control of hydraulic pump pressure steadily with fast dynamic response.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.76-76
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• 2008

The resonance properties due to the surface plasmon(SP) excitation of metal nanoparticles make the nanocomposite films promising for various applications such as optical switching devices. In spite of the well-known ultra-sensitive operation of optical switches based on a guided wave, the application of nanocomposite film(NC) has inherent limitation originating from the excessive optical loss related with the surface plasmon resonance(SPR). In this study, we addressed this problem and present the experimental and theoretical analysis on the pump-probe optical switching in prism-coupled Au(1 vol.%):$SiO_2$ nanocomposite waveguide film. The guided mode was successfully generated using a near infrared probe beam of 1550 nm and modulated with an external pump beam of 532 nm close to the SPR wavelength. We extend our approach to ultra-fast operation using a pulsed laser with 5 ns pulse width. To improve the switching speed through the reduction in thermal loading effect accompanied by the resonant absorption of pump beam light, we adopted a metallic film as a coupling layer instead of low-index dielectric layer between the high-index SF10 prism and NC slab waveguide. We observed great enhancement in switching speed for the case of using metallic coupling layer, and founded a distinct difference in origin of optical nonlinearities induced during switching operation using cw and ns laser.

• International journal of advanced smart convergence
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• 제4권1호
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• pp.64-70
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• 2015

This paper proposes fluorescent electronic ballast with high power factor and low line input current harmonics. The system performance can be improved by a charged pump circuit. Details of design and circuit operation are described. The proposed electronic ballast is modified from single-stage half bridge class D electronic ballast by adding capacitor parallel with each power switch and setting the circuit parameter to operate under class DE inverter condition. By using this proposed method the DC bus voltage can be reduced around by 50% compare with conventional class D inverter circuit. Because the power switches are operated at zero voltage switching condition and low dv/dt of class DE switching. The experimental results show that the proper frequency of the prototype is around 50 kHz with input power factor of 0.982, $THD_i$ 10.2% at full load and efficiency of more than 90%.

• 유공압시스템학회논문집
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• 제4권4호
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• pp.8-14
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• 2007

The electro-hydraulic pump is usually used in testing equipments which require one control function. But until now, it is not applied to industrial equipments which are exposed to severe working environment and require various control functions. This paper proposes a technique which controls continuously flow, pressure and power by utilizing switching control mode. Mathematical model is developed from the continuity equation for the pressurized control volume and the torque balance for the swash plate motion. To simplify the model we make the linear state equation by differentiating the nonlinear model. We analyze the stability and disturbance by using the state variable model. Finally, we review the control performances of flow, pressure and power by tests using PID controller.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권6호
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• pp.873-879
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• 2016

A charge pump circuit with very short turn-on time is presented for minimizing reference spurs in CMOS PLL frequency synthesizers. In the source switching charge pump circuit, applying proper voltages to the source nodes of the current source FETs can significantly reduce the unwanted glitch at the output current while not degrading the rising time, thus resulting in low spur at the synthesizer output spectrum. A 1.1-1.6 GHz PLL synthesizer employing the proposed charge pump circuit is fabricated in 65 nm CMOS. The current consumption of the charge pump is $490{\mu}A$ from 1 V supply. Compared to the conventional charge pump, it is shown that the reference spur is improved by dB through minimizing the turn-on time. Theoretical analysis is described to show that the measured results agree well with the theory.