• Coupled systems mechanics
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• 제12권2호
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• pp.151-165
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• 2023

In this study, a simple method for the determination of the shear correction factor for composites beam with a rectangular cross section is presented. The plane stress elasticity assumption is used after simplifications of the expression of the stress distribution in the beam. The different fiber orientation angle and volume fraction are considered in this work. The studied structure is subjected to various loading type (thermal and hygrothermal). The numerical results obtained show that there is a dependence of the shear coefficient on the orientation of the fibers. The evolution of the shear correction factors depends not only on the orientation of the fibers and also on the volume fraction and the environment. the advantage of this developed formula of the shear correction factor is to obtain more precise results and to consider several parameters influencing this factor which are neglected if the latter is constant.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.187-189
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• 2003

Conventional Switched Mode Power Supplies(SMPS) with diode-capacitor rectifier have distorted input current waveform with high harmonic content. Typically, these SMPS have a power factor lower than 0,65. To improve with this problem the power factor correction(PFC) circuit of power supplies has to be introduced. Specially. to the reduce size and manufacture cost of power conversion device, the single-stage PFC converter is increased to demand as necessary of study. in this paper, The comparative analysis of power factor correction circuit using Feedforward control with average current mode flyback converter(single-stage) and boost converter(two-stage). Also, the validity of designed and manufactured high power factor flyback converter and boost converter is confirmed by simulation and experimental results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1678-1683
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• 2003

Some characteristics of the sensitivities of the eigenvalues for beams have been found in the paper. For cantilever beams and simply supported beams, the sensitivities of the eigenvalues to the stiffness correction factor of one element are equal and opposite to the sensitivities to the mass correction factor of the symmetrically positioned element. The relationship means that to increase stiffness in one element has the same effects on the eigenvalues as to decrease mass by the same proportion in the symmetrically positioned element. For beams with other boundary conditions, however, the relationship does not hold.

• 한국산학기술학회논문지
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• 제20권6호
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• pp.314-321
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• 2019

본 연구에서 개발된 Self-Adaptive Vision Correction Algorithm (SAVCA)은 광학적 특성을 모방하여 개발된 Vision Correction Algorithm (VCA)의 총 6개의 매개변수 중 자가 적응형태로 구축된 Division Rate 1 (DR1) 및 Division Rate 2 (DR2)를 제외한 Modulation Transfer Function Rate (MR), Astigmatic Rate (AR), Astigmatic Factor (AF) 및 Compression Factor (CF) 등 4개의 매개변수를 변경하여 사용성을 증대시키기 위해 제시되었다. 개발된 SAVCA의 검증을 위해 기존 VCA를 적용하였던 2개 변수를 갖는 수학 문제 (Six hump camel back 및 Easton and fenton) 및 30개 변수를 갖는 수학 문제 (Schwefel 및 Hyper sphere)에 적용한 결과 SAVCA는 비교한 다른 알고리즘 (Harmony Search, Water Cycle Algorithm, VCA, Genetic Algorithms with Floating-point representation, Shuffled Complex Evolution algorithm 및 Modified Shuffled Complex Evolution)에 비해 우수한 성능을 보여주었다. 마지막으로 공학 문제인 Speed reducer design에서도 SAVCA는 가장 좋은 결과를 보여주었다. 복잡한 매개변수 조절과정을 거치지 않은 SAVCA는 여러 분야에서 적용이 가능할 것이다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1996년도 창립기념 전력전자학술발표회 논문집
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• pp.35-38
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• 1996

A new high power factor converter using transformer magnetizing energy for power factor correction with a single-switch/single-stage is proposed. The proposed converter gives the good power factor correction, low current harmonic distortions, and tight output voltage regulation. The prototype shows the IEC555-2 requirements are met satisfactorily with nearly unity power factor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.444-446
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• 2011

A bidirectional dual active converter with the power factor control capability is proposed as a battery charger. The source side half-bridge acts as a PWM converter that maintains the unity power factor. The battery side half-bridge converter acts as a dual active bridge (DAB) together shares the same DC link voltage with PWM converter. The imbalance voltage phenomenon is eliminated by employing asymmetric duty cycle technique. Simulation results are included to verify theoretical analysis.

• 전자공학회논문지
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• 제50권8호
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• pp.151-161
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• 2013

본 논문에서는 입력전압을 감지하지 않는 전류연속/임계동작모드 active power factor correction(PFC) circuit을 제안하였다. 기존의 입력전압을 감지하지 않는 PFC circuit의 경우 출력전류가 낮은 경 부하 조건에서 DCM 동작을 수행하고, 이에 따라 PF가 감소하는 문제가 발생한다. 제안한 PFC circuit은 70KHz의 주파수로 CCM 동작을 수행하고, 경 부하 조건에서 최대 200KHz까지 스위칭 주파수가 가변되는 CRM 동작을 수행하도록 하였다. 이를 통해 경 부하 조건에서 PF가 감소하는 문제를 해결하였다. PFC controller IC는 $0.35{\mu}m$ BCDMOS 공정을 이용하여 제작하였으며, 240W급 PFC prototype을 제작하여 실험하였다. 제안한 PFC circuit은 기존의 PFC circcuit 대비 최대 10%의 역률이 향상되었고, IEC 61000-3-2 Class D 규격에 따른 경 부하 조건에서는 최대 4% 역률이 향상되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제17권12호
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• pp.1689-1694
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• 2004

This study was conducted to develop a novel adjustment factors for 305 days using 138,103 lactation records and 1,770,764 daily records, which were based on environmental circumstances such as herd year, season, age at calving, dry period and lactating stages. The present study showed that the change of persistency of cows at the first parity from total lactacting characteristics was slowly processed, while it was rapidly changed in cows at the second parity stage. Particularly, there was an outstanding difference between the first and second parity cows. Milk yield and composition increased as the age at calving was increased. In addition, milk yield and composition were higher at the first parity on fall compared with others, and those were higher at the more than second parity on fall and winter compared with other parity stages and seasons. The cow of dry group was included into lactating records of more than second parity stage. The data indicated that optimal results arose from 45-70 days of dry period. Milk yield was decreased when dry period was longer or shorter than 45-70 days. The lactating days were divided into 17, 28 and 38 stages to compare the multiplicative correction factors. The factor was effective at 28 stages on the first parity. The total correlation coefficients were 0.93832, 0.95058 and 0.95076 at the present correction factor, 17 stage and 28 stage, respectively. At second parity, the factor was higher in dry group 1 and 3 at 17 stage, and it was higher in dry group 2 at 28 stage compared with others. Therefore, the present study showed that the percent squared bias (PSB), which was calculated from the novel correction factor, was better than previously used correction factors. Also, the present study indicated that the bias of the novel correction factor was improved, and this factor could be more accurate compared with others.

• 대한기계학회논문집A
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• 제33권10호
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• pp.1151-1157
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• 2009

Nuclear power plants applying for the continued operation over design life are required to address the effects of reactor water environment in fatigue design requirement of the ASME Code. Reactor water environmental effects are generally evaluated by calculating fatigue correction factors on fatigue usage. This paper describes the application for pressurizer surge line of environmental fatigue correction factors and the strain rate impact in the application. From this paper, the environmental fatigue correction factors resulted from the assumption of a step change in temperature are especially compared with those calculated from the data measured during plant startup. As a conclusion of this paper, the design transient conditions applied to the fatigue design may be conservative in case of the environmental fatigue evaluation.

• Journal of Electrical Engineering and Technology
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• 제11권5호
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• pp.1342-1347
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• 2016