• Journal of Advanced Marine Engineering and Technology
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• 제22권4호
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• pp.445-450
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• 1998

In the present paper the effects of combined heat and mass transfer on the fin efficiency were calculated. Sector method was used for calculating the fin efficiency of the continuous fin. The parameter Lewis No. and C which describe the combined heat and mass transfer is derived by using the heat and mass transfer analogy and effects of Lewis No. and C on the fin efficiencies were calculated.

• Journal of Power Electronics
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• 제19권6호
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• pp.1440-1448
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• 2019

In wireless power transfer systems, it is important to design resonant energy links in order to increase the power transfer efficiency and to obtain desired system performances. This paper proposes a method for designing and analyzing the resonant energy links in a series-series configured IPT (inductive power transfer) system using the FOM-rd plane. The proposed FOM-rd graphical design plane can analyze and design the voltage gain and the power efficiency of the energy links while considering changes in the misalignment between the coils and the termination load condition. In addition, the region of the bifurcation phenomena, where voltage gain peaks are split over the frequency, can also be distinctly identified on the graphical plane. An example of the design and analysis of a 100 W inductive power transfer system with the proposed method is illustrated. The proposed method is verified by measuring the voltage gain and power efficiency of implemented hardware.

• 한국응용과학기술학회지
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• 제28권3호
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• pp.367-373
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• 2011

This research is a basic researching process for producing solid fuel that mixing paper sludge and Heat Transfer Medium Oil. Under the presence of Heat Transfer Medium Oil, paper sludge is heated and dried with home appliance microwave for comparing drying efficiency and energy efficiency of different types of drying method. As a result, Heat Transfer Medium Oil and paper mixing case of drying method, OMD, is the most efficient way to shorten the time for evaporating moisture in the paper sludge. In addition, heat transfer effect and density is increased with adding Heat Transfer Medium Oil by microwave. Future more, OMD's energy cost for evaporating whole moisture is 78% cheaper than MD. Also, OMD process shows the best energy efficiency with comparing other process. Evaporation rate of paper sludge evaporation process with microwave is 11.66% increased by adding Heat Transfer Medium Oil 150g. Preheating Heat Transfer Medium Oil or improving different ways injecting Heat Transfer Medium Oil is a good way to increase a rate of initiative moisture evaporation process.

• 한국도로학회논문집
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• 제3권3호
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• pp.147-158
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• 2001

콘크리트포장의 구조적 능력을 평가하는 가장 중요한 요소 중의 하나는 하중전달효과이다. 하중전달효과는 슬래브 상 하부 온도차, 다우월바 시공여부, 포장 노후도, 그리고 균열틈 등에 영향을 받는다. 본 연구의 목적은 콘크리트 포장의 하중전달효과 특성을 파악하고 하중전달효과에 영향을 주는 요소를 정량화하고 적절한 하중전달효과 조사방법을 제시하는 것이다. 연구결과 하중전달효과는 슬래브 표면온도가 아닌 슬래브 평균온도 영향을 받는 것으로 나타났다. 하중전달효과는 온도가 내려가고 균열틈이 벌어질수록 감소하는 것으로 나타났다. 다우월바를 시공한 구간의 경우 온도변화에 따라 하중전달효과는 큰 차이를 보이지 않은 반면, 다우월바를 시공하지 않은 구간에서는 온도가 내려갈수록 하중전달효과는 급격히 감소하였다. 다우월바를 시공한 구간이라도 포장이 노후화되면 하중전달효과는 온도가 하락함에 따라 감소하는 것으로 나타났다. 본 조사대상 구간에서는 슬래브 단위온도 하락시 하중전달효과는 1.4% 감소하는 것으로 나타났다.

• 전기학회논문지P
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• 제67권4호
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• pp.221-226
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• 2018

In this paper, the power transfer efficiency analysis based on the resonant repeater in a magnetic resonance wireless power transfer system is proposed. The efficiency of the magnetic resonance method was verified by comparing the general frequency with the resonance frequency. The resonance repeater was arranged to increase the efficiency and increase the transfer distance. When using resonant repeaters, the maximum efficiency increase is about 36.23[%] and the transfer distance was extended to more than 20[cm]. Through this study, confirmed the effect of using resonance repeaters in wireless power transfer system. As a result, it can be expected that the overall technology related to wireless power transfer system will be more valuable for energy-IT technology.

• 전자공학회논문지
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• 제50권7호
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• pp.275-280
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• 2013

본 논문은 무선 충전 시스템의 최적화 기법에 대한 것으로서, 특히 캡슐형 내시경 응용을 위한 회로를 기반으로 한다. 이 논문에서는 저용량 배터리를 내장하는 무선 충전 시스템에서 전자기 유도 원리를 이용한 방식을 적용하여 배터리 용량을 필요 이상으로 증가시키지 않는 상태에서 여러 가지 상황에 대응하여 무선 전력 전송의 효율을 최적화하는 것을 목표로 하였다. 전자기 공진 코일의 무선 전력 전송의 효율을 증가시키기 위하여 전력 전송의 주요 결정 요소를 분석하고 주파수 제어에 의한 효율 최적화를 시도하였다. 모의실험 결과 제안된 최적화 기법은 무선 충전 효율을 안정화시키고 현재 문제가 되고 있는 거리 및 기생 성분에 의한 전송 효율 변이를 효과적으로 개선하는 것을 확인하였다.

• Journal of Power Electronics
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• 제19권5호
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• pp.1087-1098
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• 2019

In this paper, a detuning factor (DeFac) method is proposed to design the key parameters for optimizing the transfer power and efficiency of an Inductively Coupled Power Transfer (ICPT) system with primary-secondary side compensation. Depending on the robustness of the system, the DeFac method can guarantee the stability of the transfer power and efficiency of an ICPT system within a certain range of resistive-capacitive or resistive-inductive loads. A MATLAB-Simulink model of a ICPT system was built to assess the system's main evaluation criteria, namely its maximum power ratio (PR) and efficiency, in terms of different approaches. In addition, a magnetic field simulation model was built using Ansoft to specify the leakage flux and current density. Simulation results show that both the maximum PR and efficiency of the ICPT system can reach almost 70% despite the severe detuning imposed by the DeFac method. The system also exhibited low levels of leakage flux and a high current density. Experimental results confirmed the validity and feasibility of an ICPT system using DeFac-designed parameters.

• Journal of electromagnetic engineering and science
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• 제13권3호
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• pp.173-177
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• 2013

This paper presents a new method for analyzing the maximum efficiency of a wireless power transfer (WPT) system with multiple n resonators. The method is based on ABCD matrices and allows transformation of the WPT system with multiple n resonators into a single two-port network system. The general maximum efficiency equation of a WPT system with multiple n resonators is derived using the ABCD matrix. Use of this equation allows placement of the relay resonators for maximum efficiency even though they are asymmetrical. The general maximum efficiency equation and the method of the optimum placement are verified by a full wave simulation. The results show that the method is useful for the analysis of a WPT system with relay resonators.

• 대한전자공학회논문지SD
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• 제41권7호
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• pp.31-36
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• 2004

Vortical-Cavity Surface-Emitting Laser(VCSEL)는 in-plane 형태의 레이저와는 달리 여러 층의 distributed Bragg reflector(DBR) mirror를 반사 면으로 사용하기 때문에 광출력이나 미분양자효율(differential quantum efficiency)을 계산하는 데에 많은 어려움이 따른다. 이러한 이유로 광출력, 광출력 비 및 미분양자효율 등의 성능 지수를 계산하는 방법으로 유효 공진기 모델과 전달행렬 방법(transfer matrix method) 등이 사용되고 있다. 유효 공진기 모델은 반사율 및 문턱이득을 계산하는 데에는 적합하지만 광출력, 광출력 비 및 외부양자효율을 계산하는 데에는 오차를 보인다. 그 이유는 유효 공진기 모델이 금속 전극 개구부 바로 아래 GaAs 층에서의 빛의 흡수는 고려하지 못하기 때문이다. 이 논문에서는 유효 공진기 모델로부터 구한 성능 지수 값들을 전달행렬 방법으로부터 구한 값들과 비교ㆍ검토하여, 유효 공진기 모델의 타당성에 대하여 살펴보고 전달행렬 방법의 유용성을 재확인하였다.

• 산업경영시스템학회지
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• 제18권36호
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• pp.297-306
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• 1995

An automatic transfer line consists of several stages(groups of stations) in series into one system by a common transfer mechanism and a common control system. In this system losses of the efficiency are evidenced in periods where a stage is forcod down- starved or blocked. The efficiency of an automatic transfer line can be improved by providing buffer storages between a stage or the length of line common senses there are several critical factors, system configurations relative position, and buffer capacity allocations in automatic transfer line are considered with a point of view production rates, average stock, and mean delay. The propose of this paper is to provide the robust designs by Taguchi method which improve the efficiency of four-stage transfer line.