• 한국통신학회논문지
• /
• 제21권6호
• /
• pp.1425-1429
• /
• 1996

누락펄스가 발생할 시 PRI 분석을 위한 전형적인 sequence search 알고리즘은 harmonic 문제를 발생시킨다. 본 논문에서 이러한 harmonic 문제를 해결할 수 있는 PRI 분석 알고리즘을 제안한다. 분석해야 할 전체 PRI 범위를 harmonic이 없도록 subband 로 나눈 후, sequence search를 forward 및 backward로 행한다. 전형적인 sequence search 알고리즘에 비하여 제안한 알고리즘의 성능이 증대된다.

• 조명전기설비학회논문지
• /
• 제18권4호
• /
• pp.181-187
• /
• 2004

3상 4선식 배전계통을 채용하는 우리나라는 비선형 부하의 증가로 중성선에는 많은 중성선 고조파 전류가 관측되고 있다. 또한 접지 임피던스는 고조파가 있는 중성선 전류에 영향 끼친다고 알려져 있다. 전위 강하법에 따라 현장에서 실측한 고조파 전류와 전압을 측정하고, Pattern Search 기법으로 고조파 해석용 접지 임피던스를 모델링 하였다. 여기서 구한 임피던스 모델은 현장 시험에 의한 임피던스 모델과 비교하여 유사한 결과를 얻었고, 접지 시스템의 고조파 및 과도 응답 특성을 평가하는데 활용될 것으로 사료된다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
• /
• pp.185-186
• /
• 2018

The slabfrom, which is commonly used in construction sites, has drawbacks in that the workability of the workers is reduced due to their heavy weight. This study investigates the possibility of design optimization of euro form between structural stability and weight using harmonic search algorithm. The harmonic search algorithm is a metaheuristic optimization technique that obtains multiple optimal solution candidates through iterative. As a result of multiple attempts of optimization through the algorithm, it was possible to design the formwork which is structurally stable and light in weight than the existing formwork.

• Journal of Power Electronics
• /
• 제19권6호
• /
• pp.1458-1466
• /
• 2019

Multilevel inverters have appeared as a successful and utilitarian solution in many power applications. The prime objective of an inverter is to keep the fundamental component of the output voltage of a multilevel inverter at a preferred value. Equally important is the need to keep the harmonic components in the output voltage within stated harmonic limits. Therefore, the basis of this research is to develop a harmonic minimization function that optimizes the switching angles of cascaded H-bridge multilevel inverter. Due to benefits of the Cuckoo Search (CS) algorithm, it is applied to determine the switching angles, which are further used to generate the switching pattern for firing the H-bridges of multilevel inverter. Simulation results are compared with SPWM based firing scheme. The switching frequency for SPWM firing scheme is taken as 200 Hz since the switching losses are increased when switching frequency is high. To validate the ability of Cuckoo Search optimized firing scheme in minimization of harmonics, experimental results obtained from hardware prototype of Five Level Cascaded H-Bridge Multilevel Inverter equipped with a FPGA controller are presented to verify the simulation results.

• Steel and Composite Structures
• /
• 제34권3호
• /
• pp.409-421
• /
• 2020

In the optimized structure sizing, the optimization methods are inserted in this context in order to obtain satisfactory solutions, which can provide more economical structures, besides allowing the consideration of the factors related to the environmental impacts in the structural design. This work proposes a mathematical model for the optimization of steel-concrete composite beams aiming to minimize the monetary cost and the environmental impact, using the Harmonic Search optimization method. Discrete variables were the dimensions of the steel profiles and the thickness of the collaborating slab of the composite steel-concrete beam. The proposed model was implemented in Fortran programming language and based on improvements in the structure of the optimization method proposed by Medeiros and Kripka (2017). To prove the effectiveness and applicability of the model, as well as the Harmonic Search method, analyzes were performed with different configurations of steel-concrete composite beams, in order to provide guidelines that make the use of these systems more streamlined. In general, the Harmonic Search optimization method has proved to be efficient in the search for the optimized solutions, as well as important considerations on the optimization of the monetary and environmental costs of steel-concrete composite beams were obtained from the developed examples.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 A
• /
• pp.369-371
• /
• 2004

With the proliferation of nonlinear loads, high neutral harmonic currents in three-phase four-wire distribution system have been observed. It has been. known that the ground impedance has an effect on the neutral currents of a system which operates with harmonics present. On-site measurements of harmonic currents and voltages according to the fell-of-potential method under case study system were made and the ground impedance modeling using the pattern search method for the harmonic analysis was developed. The ground impedance model obtained by the proposed method was compared with the frequency characteristics by field tests and has shown appropriate results, and would be applicable to evaluate the harmonic and transient response characteristics of the ground system.

• Journal of Information Processing Systems
• /
• 제14권5호
• /
• pp.1237-1253
• /
• 2018

Harmony search algorithm is an emerging meta-heuristic optimization algorithm, which is inspired by the music improvisation process and can solve different optimization problems. In order to further improve the performance of the algorithm, this paper proposes an improved harmony search algorithm. Key parameters including harmonic memory consideration (HMCR), pitch adjustment rate (PAR), and bandwidth (BW) are optimized as the number of iterations increases. Meanwhile, referring to the genetic algorithm, an improved method to generate a new crossover solutions rather than the traditional mechanism of improvisation. Four complex function optimization and pressure vessel optimization problems were simulated using the optimization algorithm of standard harmony search algorithm, improved harmony search algorithm and exploratory harmony search algorithm. The simulation results show that the algorithm improves the ability to find global search and evolutionary speed. Optimization effect simulation results are satisfactory.

• 전기전자학회논문지
• /
• 제21권4호
• /
• pp.416-419
• /
• 2017

본 논문에서는 고속 DDR3/DDR4 SDRAM을 위한 새로운 디지털 지연고정루프 (delay-locked loop: DLL)를 제안한다. 제안하는 디지털 DLL은 디지털 지연라인의 boundary switching 문제에 의한 jitter 증가 문제를 제거하기 위하여 위상보간 (phase interpolation) 방식의 파인지연라인 (fine delay line)을 채택하였다. 또한, 제안하는 디지털 DLL은 harmonic lock 문제를 제거하기 위하여 새로운 점진직 검색 (gradual search) 알고리즘을 사용한다. 제안하는 디지털 DLL은 1.1V, 38-nm CMOS DRAM 공정으로 설계되었으며, 0.25-2.0 GHz의 주파수 동작 영역을 가진다. 2.0 GHz에서 1.1 ps의 피크-투-피크 (p-p) 지터를 가지며, 약 13 mW의 전력소모를 가진다.

• Journal of Power Electronics
• /
• 제18권4호
• /
• pp.1037-1050
• /
• 2018

This paper presents a novel reconfigurable selective harmonic elimination technique to control harmonics over a wide range of Modulation Indexes (MI) in Multi-Level Inverter (MLI). In the proposed method, the region of the MI is divided into various sectors and expressions are formulated with different switching patterns for each of the sectors. A memetic BBO-MAS (Biogeography Based Optimization - Mesh Adaptive direct Search) optimization algorithm is proposed for solving the Selective Harmonic Elimination - Pulse Width Modulation (SHE-PWM) technique. An experimental prototype is developed using a Field Programmable Gate Array (FPGA) and their FFT spectrums are analyzed over a wide range of MI using a fluke power logger. Simulation and experimental results have validated the performance of the proposed optimization algorithms and the reconfigurable SHE-PWM technique. Further, the sensitivity of the harmonics has been analyzed considering non-integer variations in the magnitude of the input DC sources.

• Journal of Power Electronics
• /
• 제13권4호
• /
• pp.712-718
• /
• 2013

This paper proposes a control method for reducing the total harmonic distortion (THD) of the grid current of three-phase grid-connected inverter systems when the grid voltage is distorted. The THD of the grid current caused by grid voltage harmonics is derived by considering the phase delay and magnitude attenuation due to the hardware low-pass filter (LPF). The Cauchy-Schwarz inequality theory is used in order to search more easily for the minimum point of the THD. Both the gain and angle of the compensation voltage at the minimum point of the THD of the grid current are derived with the variation of cut-off frequencies of the hardware LPF. Simulation and experimental results show the validity of the proposed control methods.