• 마케팅과학연구
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• 제13권
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• pp.183-208
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• 2004

최근 영세한 국내 의약품 유통시장을 근대화하고 유통질서 확립을 위해 도매상 기능의 강화와 도매상과 약국간 협력체계 확립의 중요성에 대한 정부와 업계의 관심이 높아지고 있다 본 연구는 의약품 유통경로에서의 도매상과 소매상간 관계특성 변수들을 파악하고 이들 변수들과 협력간 관계를 실증분석 하였다. 기존 연구와 이론적 배경을 토대로 의약품 유통경로에서의 관계특성 변수들로 관계주의, 보상적 힘, 신뢰, 의존을 선정하고 이들 변수들과 협력과 만족간 관계를 살펴보았다. 연구결과, 보상적 힘을 제외한 관계특성 변수들은 협력에 유의한 영향을 미치는 것으로 나타났으며, 협력은 만족에 유의한 영향을 미치는 것으로 나타났다. 이러한 연구결과를 토대로 의약품 유통경로에서 도매상과 중소형 약국간 협력관계를 강화시킬수 있는 방안들을 제시하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권9호
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• pp.4145-4164
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• 2016

Energy harvesting is an increasingly attractive source of power for cellular networks, and can be a promising solution for green networks. In this paper, we consider a cellular network with power beacons powering multiple mobile terminals with microwave power transfer in energy beamforming. In this network, the power beacons are powered by grid and renewable energy jointly. We adopt a dual-level control architecture, in which controllers collect information for a core controller, and the core controller has a real-time global view of the network. By implementing the water filling optimized power allocation strategy, the core controller optimizes the energy allocation among mobile terminals within the same cluster. In the proposed green energy cooperation paradigm, power beacons dynamically share their renewable energy by locally injecting/drawing renewable energy into/from other power beacons via the core controller. Then, we propose a new water filling optimized green energy cooperation management strategy, which jointly exploits water filling optimized power allocation strategy and green energy cooperation in cellular networks. Finally, we validate our works by simulations and show that the proposed water filling optimized green energy cooperation management strategy can achieve about 10% gains of MT's average rate and about 20% reduction of on-grid energy consumption.

• Journal of Power Electronics
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• 제16권2호
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• pp.464-472
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• 2016

This study applies the selective harmonic elimination (SHE) technique to design and operate a regulated AC/DC/AC power supply suitable for maritime military applications and underground trains. The input is a single 50/60 Hz AC voltage, and the output is a 400 Hz regulated voltage. The switching angles for a multi-level inverter and transformer turns ratio are determined to operate with special connected transformers with equal power ratings and produce an almost sinusoidal current. As a result of its capability of directly controlling harmonics, the SHE technique is applicable to apparatus with congenital immunity to specific harmonics, such as series-connected transformers, which are specially designed to equally share the total load power. In the present work, a single-phase 50/60 Hz input source is rectified via a semi-controlled bridge rectifier to control DC voltage levels and thereby regulate the output load voltage at a constant level. The DC-rectified voltage then supplies six single-phase quazi-square H-bridge inverters, each of which supplies the primary of a single-phase transformer. The secondaries of the six transformers are connected in series. Through off-line calculation, the switching angles of the six inverters and the turns ratios of the six transformers are designed to ensure equal power distribution for the transformers. The SHE technique is also employed to eliminate the higher-order harmonics of the output voltage. A digital implementation is carried out to determine the switching angles. Theoretical results are demonstrated, and a scaled-down experimental 600 VA prototype is built to verify the validity of the proposed system.

• 전력전자학회논문지
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• 제15권3호
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• pp.207-217
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• 2010

현재 디지털 제품의 사용의 증가로 제품 내부의 DC 전원의 사용이 증가하는 가운데 시스템의 구동전압을 공급하기 위해 기기내부에 장착된 AC/DC컨버터로 인한 입력전류의 역률저하 및 고조파 증가, 그리고 AC/DC 컨버터에서 발생하는 변환 손실 등의 문제가 발생한다. 하이브리드 배전시스템은 기존의 AC부하(전동기 부하 및 변압기 부하)와 DC 부하(컴퓨터, TV, LED조명)에 AC 와 DC 전원을 동시에 공급하며, 직류출력 전원(신재생에너지 및 배터리뱅크)과 상용전원에서 전력을 공급받아 사용자에게 DC 및 AC 전력을 공급해주는 시스템으로 상용전원의 효율을 향상시키고 신재생에너지의 사용 편의성을 올리며 가정에 AC와 DC를 동시에 공급하는데 주목적이 있다. 본 논문을 통해 DC 및 AC 동시 배전을 위해 기존 교류부하의 직류특성에 관한 연구를 하며, 하이브리드 배전의 적절한 DC 전압레벨을 선정한다.

• 전력전자학회논문지
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• 제20권2호
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• pp.115-121
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• 2015

Stand-alone inverter supplies constant voltage to loads. However, when a three-phase stand-alone inverter supplies unbalanced load, the generated output voltages also become unbalanced. The nonlinear characteristics of inverter dead time cause a more serious distortion in the output voltage. With unbalanced load, voltage distortion caused by dead time differs from voltage distortion under balanced load. Phase voltages in the stationary reference frame include unbalanced odd harmonics and then, d-q axis voltages in the synchronous reference frame have even harmonics with different magnitude, which are mitigated by the proposed multiple resonant controller. This study analyzes the voltage distortion caused by unbalanced load and dead time, and proposes a novel dead time compensation method. The proposed control method is tested on a 10-kW stand-alone inverter system, and shows that total harmonic distortion (THD) is reduced to 1.5% from 4.3%.

• 전기학회논문지
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• 제65권4호
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• pp.567-575
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• 2016

This paper proposed the voltage control of stand-alone inverter for power quality improvement under unbalanced and non-linear load. The 3-phase DC-AC inverter controls CVCF(Constant Voltage Constant Frequency) and selective harmonic eliminate method in stand-alone mode by PR controller, and the stand-lone inverter supplies stable sinusoidal voltage to balanced, unbalanced and non-linear loads. The total harmonic distortion(THD) of line-to-line load voltage($V_{LL}$) is 1.2% in the balanced load. THD of $V_{LL}$ is reduced from 5.2% to 1.4% and 6.7% to 3.5%, respectively unbalanced and non-linear load. The stand-alone inverter can be supplies sinusoidal balanced voltage to unbalanced load because the voltage unbalanced factor(VUF) of $V_{LL}$ is reduced from 5.2% to 1.4% in the unbalanced load. Feasibility of control method for a stand-alone inverter will be verified through 30kW stand-alone inverter system.

• Journal of Advanced Marine Engineering and Technology
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• 제40권3호
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• pp.223-227
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• 2016

다이오드를 이용한 정류기는 산업현장에서 널리 응용되고 있다. 그러나 입력전류에 많은 저차고조파가 포함되어 공급전압을 왜곡시켜 전력의 품질을 저하시키므로 이를 완화시킬 수 있는 적절한 설비가 필요하다. 또한 고조파 전류는 전력계통의 전압 왜곡, 가열 및 소음 등을 유발하여 효율을 떨어뜨린다. 고조파를 감소시키고 역률을 상승시키기 위하여 입력전류가 연속적이 되도록 하는 부스트 컨버터가 등장하였다. 본 논문에서는 입력전류에 포함된 고조파 전류를 감소시키고, 역률을 증가시킬 수 있을 뿐 아니라 전체 정류기 효율을 상승시키는 부스트 컨버터를 제안하였다. 이는 기존의 부스트 컨버터에 비해 전류가 통과하는 반도체의 개수가 감소하여 효율의 상승을 기대할 수 있다. 또한, 소프트웨어 PSIM을 활용하여 제안된 변환기의 유효성을 입증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.67-68
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• 2016

The accurate measurement of magnet power supplies (MPS) output currents is essential to delivering stable and repeatable currents to magnets in particle accelerators. An essential element in guaranteeing and evaluating the required performance is the current measurement device and methode. In this paper, we discuss instrument and methods for precision current measurement and performance of the PLS-II MPS.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.460-465
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• 1998

Due to high power ratings and low conduction loss, the IGBT has become more attractive in switching power supplies. However, its turn-on and turn-off characteristics cause severe switching loss and switching frequency limitation. This paper proposes 2.4kW, 48V, high efficiency half-bridge DC-DC converter using paralleled IGBT-MOSFET switch concept, where each of IGBT and MOSFET plays its part during on-periods and switching instants. The switching loss is analyzed by using the linearized model and the opteration of the converter are investigated by simulation results.

• 한국산업융합학회 논문집
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• 제21권5호
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• pp.235-240
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• 2018

The generator of an automobile supplies electric voltage and current for various electric components. The supplied voltage can be changed by sudden variation of the electric load. The voltage was controlled by independent power supply in the study. The TPS and APS signal was changes as the voltage of the power supply. The ECU output voltage and OBD signal voltage was changed also as the variance of the power supply.