• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1389-1399
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• 2015

This research suggests maximum power point tracking (MPPT) for the solar photovoltaic (PV) power scheme using a new constant voltage (CV) fractional order incremental conductance (FOINC) algorithm. The PV panel has low transformation efficiency and power output of PV panel depends on the change in weather conditions. Possible extracting power can be raised to a battery load utilizing a MPPT algorithm. Among all the MPPT strategies, the incremental conductance (INC) algorithm is mostly employed due to easy implementation, less fluctuations and faster tracking, which is not only has the merits of INC, fractional order can deliver a dynamic mathematical modelling to define non-linear physiognomies. CV-FOINC variation as dynamic variable is exploited to regulate the PV power toward the peak operating point. For a lesser scale photovoltaic conversion scheme, the suggested technique is validated by simulation with dissimilar operating conditions. Contributions are made in numerous aspects of the entire system, including new control algorithm design, system simulation, converter design, programming into simulation environment and experimental setup. The results confirm that the small tracking period and practicality in tracking of photovoltaic array.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2577-2583
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• 2009

Presented are the formation of iron oxide layers on evaporator tubes in an actual fossil power plant operated under all volatile treatment (AVT) condition and an experimental simulation of iron oxide formation in the presence of ferrous and ferric ions. After actual operations for 12781 and 36326 hr in the power plant, two iron oxide layers of magnetite on the evaporator tubes were found: a continuous inner layer and a porous outer layer. The experimental simulation (i.e., artificial corrosion in the presence of ferrous and ferric ions at 100 ppm level for 100 hr) reveals that ferrous ions turn the continuous inner oxide layer on tube metal to cracks and pores, while ferric ions facilitate the production of porous outer oxide layer consisting of large crystallites. Based on a comparison of the oxide layers produced in the experimental simulation with those observed on the actually used tubes, we propose possible routes for oxid layer formation schematically. In addition, the limits of the proposed corrosion routes are discussed in detail.

• 전기학회논문지
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• 제64권4호
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• pp.567-572
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• 2015

Discharge characteristics of linear microwave plasma were investigated by using fluid simulation of 2D axis-symmetry based on finite elements method. The microwave power was 2.45 GHz TEM mode and transmitted through linear antenna. Resistive power and pressure were considered simulation variables and argon was used for working gas. A decrease of electron density along the quartz tube was observed in low power condition but relatively uniform plasmas were generated in chamber by increasing the resistive power. The electron temperature was highly detected near the surface of quartz tube because the electron was heated only dielectric surface. The power transmission efficiency decreased and characteristics of surface plasma were observed in high electron density condition.

• Transactions on Electrical and Electronic Materials
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• 제18권4호
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• pp.195-198
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• 2017

This research analyzed the electrical characteristics of an 80 V optimal trench power MOSFET (metal oxide field effect transistor) for mobile applications. The power MOSFET is a fast switching device in fields with low voltage(<100 V) such as mobile application. Moreover, the power MOSFET is a major carrier device that is not minor carrier accumulation when the device is turned off. We performed process and device simulation using TCAD tools such as MEDICI and TSUPREM. The electrical characteristics of the proposed trench gate power MOSFET such as breakdown voltage and on resistance were compared with those of the conventional power MOSFET. Consequently, we obtained breakdown voltage of 100 V and low on resistance of $130m{\Omega}$. The proposed power MOSFET will be used as a switch in batteries of mobile phones and note books.

• Journal of Biosystems Engineering
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• 제33권5호
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• pp.289-295
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• 2008

The task of chemical spraying has been seriously considered as an irritating and annoying job for Korean rice farmers. An agricultural unmanned helicopter was suggested to solve this problem so as the farmers to have more decent farming condition. The objectives of this study were to analyze the adoptability of an experimental rotor blade (SW05) using the CFD simulation and also to compare the simulation results with experimental results. The simulation results showed that the induced power of this rotor reached to $57{\sim}63%$ of total power and the profile power was about $37{\sim}43%$ of total power. Therefore it can be concluded that this rotor's performance characteristics were not so efficient for the size of unmanned helicopter due to the low induced power and high profile power relatively compared with ones of conventional rotors. The comparison with experimental results showed that the tested lifts were less than 70% of simulated ones at the grip pitch of $12^{\circ}$ and decreased to 40% at the $18^{\circ}$ grip pitch. Therefore, it can be concluded that the rotor was too oversized to be used for a 15.4 kW (21 PS) engine.

• Journal of Power Electronics
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• 제18권6호
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• pp.1879-1888
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• 2018

With power level of grid-connected converters rising, the switching frequency of the switching devices is commonly greatly reduced to improve its power capacity. However, this results in serious couplings of the dq current components, which leads to degradation of the static and dynamic performances of grid-connected converters and fluctuations of the reactive power in dynamic processes. In this paper, complex vector models under low switching frequency are established for an L/LCL grid-connected converter, and the relationship between the switching frequency and the coupling degree is analyzed. In addition, a series decoupling current control strategy is put forward. It is shown that the proposed control strategy can eliminate the couplings, improve the performances and have good robustness to parameter variations through static and dynamic characteristics analyses and a sensitivity analysis. Experimental and simulation results also verify the correctness of the theoretical analyses and the superiority of the proposed control strategy.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2006년도 춘계종합학술대회
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• pp.259-262
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• 2006

본 논문에서는 2.4 GHz ZigBee 응용을 위한 저전력 CMOS LNA(Low Noise Amplifier)를 설계하였다. 제안된 회로의 설계에서 TSMC $0.18{\mu}m$ CMOS 공정을 사용하였고 current-reused stage를 이용한 2단 cascade 구조를 채택하였다. 본 논문에서는 LNA 설계 과정을 소개하고 ADS(Advanced Design System)를 이용한 모의실험 결과를 제시하여 검증하였다. 모의실험 결과, 1.0V의 전압이 인가될 때 1.38mW의 매우 낮은 전력 소모를 확인하였다. 또한 13.83dB의 최대 이득, -20.37dB의 입력 반사 손실, -22.48dB의 출력 반사 손실 그리고 1.13dB의 잡음 지수를 보였다.

• 한국항만학회지
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• 제2권1호
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• pp.75-106
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• 1988

As port transport system consists of subsystems such as navigation system, cargo handling system, storage system, inland transport system, and Management and Information system, the productivity of this system is determined by the minimum level of subsystem. From the viewpoint of elaborating the efficiency of integrated system, it is valuable to determine the optimal level of harbour tug boat which is the most important factor of navigation system. This paper treats the optimal amount of harbour tug boat by simulation, and applied to Pusan port. In the course of simulation, an emperical formula is introduced for determining the Horse Power (HP) of tug boat by the ship's gross tonnage (G/T) refering to the cases of various ports of other countries, that is ; $Y=9.96X^{0.6}+569$. X : The gross tonnage of vessel (G/T). Y : The Horse Power (HP) of tug boat. The results of the simulation are summarized as follows ; 1) In 1987, three or four low-powered harbour tug boats, five mid-powered harbour tug boats and four high-powered harbour tug boats are necessary in the mean level. But, five or seven low-powered harbour tug boats, ten mid-powered harbour tug boats and eight high-powered harbour tug boats are necessary lest delay should occur at all. 2) In 1992, 1lee or four low-powered harbour tug boats, six mid-powered harbour tug boats and seven high-powered harbour tug boats are estimated and be necessary in the mean level.

• 전기학회논문지
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• 제63권7호
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• pp.883-888
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• 2014

The paper describes the parameter tuning of power system stabilizer (PSS) for a power plant based on hybrid system modeling. The existing tuning method based on bode plot and root locus is well applied to keep power system stable. However, due to linearization of power system and an assumption that the parameter ratio of the lead-lag compensator in PSS is fixed, the results cannot guarantee the optimal performances to damp out low-frequency oscillation. Therefore, in this paper, hybrid system modeling, which has a DAIS (differential-algebraic-impusive-switched) structure, is applied to conduct nonlinear modeling for power system and find optimal parameter set of the PSS. The performances of the proposed method are carried out by time domain simulation with a single machine connected to infinite bus (SMIB) system.

• 한국통신학회논문지
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• 제29권1C호
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• pp.149-156
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• 2004

본 논문에서는 저전력 멀티미디어 통신을 위한 새로운 전력 의식 움직임 추정 기법을 제안한다. 동영상 압축 기법에서 가장 많은 전력을 소모하는 것은 움직임 추정 기법인데, 일반적으로 성능이 우수한 기법일수록 전력 소모도 높다. 제안하는 움직임 추정 기법에서는 서로 다른 전력 소모와 성능을 가지는 여러 개의 움직임 추정 기법 중에서 연산량과 전력 소모의 절충을 고려하여 최적의 움직임 추정 기법을 실행 중에 적응적으로 선택한다. 제안하는 움직임 추정 기법은 현재 사용되는 대부분의 움직임 추정 기법에 쉽게 적용될 수 있으며, 추가되는 연산량이나 하드웨어 부담도 거의 없다. 모의 실험 결과에 따르면 제안하는 움직임 추정 기법은 기존의 움직임 추정 기법에 비교하였을 때 동일한 성능에서 전력 소모를 1/15.7~1/5.6으로 줄일 수 있었다.