• Journal of Advanced Marine Engineering and Technology
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• 제17권4호
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• pp.11-19
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• 1993

The experimental study was carried out to investigate the stability and the performance characteristics of the aero-valved pulsating combustion system with maximum operating capacity of 60KW. The effect of geometry of combustion system on the stable condition, the flammability limit, the total pressure oscillation amplitude, and the operating frequency can be identified, and the maximum turn-down-ratio is obtained up to 3.3. The total pressure oscillation amplitude can be controlled by tunning the length of the air inlet pipe. The empirical equation with which the operating frequency can be approximated is proposed and the discrepancy is within 5%. The volumetric efficiency is identified to be one of the important parameters determining the upper flammability limit and the maximum value of which is approximately 22%.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.487-488
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• 2006

In this paper, we analyzed the FBGA packages operating in high speeds and high frequency rates for DRAM. Using 3D simulations, we could extract s-parameters of packages. We realize that the proposed FBGA package does not operate properly at 3Gbps bacause the FBGA package have delta-I noise($V_{{\Delta}I-peak}$) of 132.0mV and crosstalk of 300mV, which is 25% of the operating clock level.

• Journal of Electrical Engineering and Technology
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• 제3권4호
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• pp.499-508
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• 2008

Frequency regulation in off-normal conditions has been an important problem in electric power system design/operation and is becoming much more significant today due to the increasing size, changing structure and complexity of interconnected power systems. Increasing economic pressures for power system efficiency and reliability have led to a requirement for maintaining power system frequency closer to nominal value. This paper presents a decentralized frequency control framework using a modified low-order frequency response model containing a proportional-integral(PI) controller. The proposed framework is suitable for near-normal and emergency operating conditions. An $H_{\infty}$ control technique is applied to achieve optimal PI parameters, and an analytic approach is used to analyse the system frequency response for wide area operating conditions. Time-domain simulations with a multi-area power system example show that the simulated results agree with those predicted analytically.

• 전기학회논문지P
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• 제50권3호
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• pp.101-108
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• 2001

Frequency is an important operating parameter of a power system. Electric power systems sustain transient frequency swings whenever the balance between generation and load does not no longer hold. To cope with this constraints, it requires an accurate and high speedy frequency deviation estimation technique and suitable adjustment to obtain the Power system energy balance. This paper describes a digital signal processing technique for measuring the operating frequency of a power system. The fundamental frequency component of 3-phase signal is first extracted by using an algorithm based on FIR filter. The rate change of the phase angle is used for estimation. To confirm the validity of the proposed algorithm, the simulation studies carried out on a typical 154KV double T/L system by using EMTP software. Some test results are presented in the paper.

• 한국정보통신학회논문지
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• 제20권12호
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• pp.2401-2409
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• 2016

안드로이드 CPU 거버너는 CPU 주파수를 낮추어 CPU 공급 전압을 감소시키는 DVFS (Dynamic Voltage Frequency Scaling) 기반 전력 관리 기법을 사용한다. 그러나 CPU 주파수의 감소는 태스크의 실행 속도 지연을 유발한다. 이로 인해 태스크의 응답 시간 및 마감 시한 초과율이 증가하여 태스크가 제공하는 서비스의 품질 하락이 발생한다. 이에 본 논문에서는 다양한 안드로이드 CPU 거버너들을 전력 소비와 태스크의 응답성 및 마감 시한 측면에서 분석하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.315-318
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• 2002

In this paper, we have studied about the determination methode of the operating frequency, and the design technique for the self-exited electronic ballast. Because we use the saturation characteristics of the ferrite core, the variation of the B/H curve characteristics for the selected core in the most important factor for the stabilization. Although it is impossible to fix the operation frequency, the self-exited electronic ballast is widely used because of its cost and the simplicity of its structure.

• KIEE International Transactions on Power Engineering
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• 제3A권1호
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• pp.17-26
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• 2003

In this paper, the comparative steady-state operating performance analysis algorithms of the stand-alone single-phase self-excited induction generator (SEIG) is presented on the basis of the two nodal admittance approaches using the per-unit frequency in addition to a new state variable de-fined by the per-unit slip frequency. The main significant features of the proposed operating circuit analysis with the per-unit slip frequency as a state variable are that the fast effective solution could be achieved with the simple mathematical computation effort. The operating performance results in the simulation of the single-phase SEIG evaluated by using the per-unit slip frequency state variable are compared with those obtained by using the per-unit frequency state variable. The comparative operating performance results provide the close agreements between two steady-state analysis performance algorithms based on the electro-mechanical equivalent circuit of the single-phase SEIG. In addition to these, the single-phase static VAR compensator; SVC composed of the thyristor controlled reactor; TCR in parallel with the fixed excitation capacitor; FC and the thyristor switched capacitor; TSC is ap-plied to regulate the generated terminal voltage of the single-phase SEIG loaded by a variable inductive passive load. The fixed gain PI controller is employed to adjust the equivalent variable excitation capacitor capacitance of the single-phase SVC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.148-151
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• 2005

This paper proposes a high speed interface using redundant multi-valued logic for high speed communication ICs. This circuit is composed of encoding circuit that serial binary data are received and converted into parallel redundant multi-valued data, and decoding circuit that convert redundant multi-valued data to parallel binary data. Because of the multi-valued data conversion, this circuit makes it possible to achieve higher operating speeds than that of a conventional binary logic. Using this logic, a 1:4 demultiplexer (DEMUX, serial-parallel converter) IC was designed using a 0.35${\mu}m$ standard CMOS Process. Proposed demultiplexer is achieved an operating speed of 3Gb/s with a supply voltage of 3.3V and with power consumption of 48mW. Designed circuit is limited by maximum operating frequency of process. Therefore, this circuit is to achieve CMOS communication ICs with an operating speed greater than 3Gb/s in submicron process of high of operating frequency.

• 전기학회논문지
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• 제65권3호
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• pp.382-387
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• 2016

This paper deals with the assessment of voltage sags regarding the variation of system operating conditions. In general, voltage sag assessment is performed by assuming the constant operating condition throughout the year. However, the assumption can lead to assessment errors in case of considerable changes of system operation condition. This paper presents a method to estimate ESF(expected sag frequency) considering the operating conditions according to the changes of power demand throughout the year.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.440_441
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• 2009

The standard for the frequency protection of distributed generation in Korea Electric Power Corporation (KEPCO)'s standard doesn't include the setting of frequency protection. Therefore, this paper analyzes the correlation between the frequency protection requirements and the stability of grid-connected PV system for the adjustable operating setting of frequency protection. The distribution system interconnected with 3 MW PV system is modeled by Matlab/Simulink. The various value of frequency is simulated. For studied cases, the stability of PV system is analyzed. It is concluded that the operating setting of frequency protection can be determined by the stability of PV system.