• 제목/요약/키워드: Analytical

검색결과 17,717건 처리시간 0.044초

전력 반도체 $p^{+}n$ 접합의 해석적 항복전압 (Analytical Breakdown Voltages of $p^{+}n$ Junction in Power Semiconductor Devices)

  • 정용성
    • 대한전자공학회논문지SD
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    • 제42권10호
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    • pp.9-18
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    • 2005
  • Si, GaAs, InP 및 $In_{0.53}Ga_{0.47}AS$ 계단형 $p^{+}n$ 접합에서의 항복전압을 위한 해석적 표현식을 유도하였다. 해석적 항복전압을 위해 각 물질에 대한 Marsland의 lucky drift 파라미터를 이용하여 유효이온화계수를 각각 추출하였고, 이의 이온화 적분을 통해 얻은 해석적 항복전압 결과는 $10^{14}cm\;^{-3}\~5\times10\;^{17}cm\;^{-3}$도핑 농도 범위에서 실험 결과와 $10\%$ 오차 범위 이내로 잘 일치하였다.

NSM 보강 RC보의 부착파괴 제한에 관한 해석적 연구 (An Analytical Study on Limits of Debonding Failure for RC Beams strengthened with NSM Reinforcements)

  • 정우태;박종섭;박영환
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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    • pp.153-156
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    • 2006
  • This paper presents an analytical results on limits of debonding failure for RC beams strengthened with near-surface mounted(NSM) CFRP strips. An analytical model was derived to predict the failure mode and the maximum load. An analytical model has two assumptions. The first is that the debonding failure occurs at the epoxy-concrete interfaces. The second is that the debonding failure occurs at the end of the FRP reinforcement due to concentration of shear stress. Results of the comparison of existing test data and analytical model data have predicted the failure mode and the maximum load well. Also, this paper proposed limits of debonding failure to prevent the debonding using the strengthening area and the groove depth.

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Magnetic charge를 이용한 Axial-gap 전동기의 특성해석 (Characteristic Analysis of Axial-gap Motor using Magnetic Charge)

  • 이상호;김도진;홍정표
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2007년도 제38회 하계학술대회
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    • pp.997-998
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    • 2007
  • This paper deals with analytical solution concerning the image method using the magnetic charge instead of 3D FEA(finite element analysis) in the slotless single air-gap motor. The theory of analytical method and the design procedures are introduced. The reliability and validity of proposed analytical solution are verified through the comparison with the results of commercial 3D FE software. In addition, calculation time between proposed analytical solution and 3D FEA is compared. Finally, characteristics, such as Back-EMF and phase resistance, between calculated and experimental results are compared. From the verification with 3D FEA and experimental results, it is proved that presented analytical method provided very effective and precise results.

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Precise Analytical Solution for the Peak Gain of LLC Resonant Converters

  • Hong, Sung-Soo;Cho, Sang-Ho;Roh, Chung-Wook;Han, Sang-Kyoo
    • Journal of Power Electronics
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    • 제10권6호
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    • pp.680-685
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    • 2010
  • Although LLC resonant converters have the advantages of a wide operation range and high efficiency, the lack of an analytical solution for the peak gain makes it difficult to optimize the resonant tank design, when considering not only the normal condition but also the holdup time requirement. In this paper, based on a mathematical analysis of a LLC resonant converter at the peak gain point, an analytical solution for the peak gain has been developed. By using the developed analytical solution, the peak gain with given resonant tank parameters can be obtained. To confirm the validity of the developed analytical solution, simulations and experimental results are compared.

Nonlinear vibration analysis of a type of tapered cantilever beams by using an analytical approximate method

  • Sun, Weipeng;Sun, Youhong;Yu, Yongping;Zheng, Shaopeng
    • Structural Engineering and Mechanics
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    • 제59권1호
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    • pp.1-14
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    • 2016
  • In this paper, an alternative analytical method is presented to evaluate the nonlinear vibration behavior of single and double tapered cantilever beams. The admissible lateral displacement function satisfying the geometric boundary conditions of a single or double tapered cantilever beam is derived by using Rayleigh-Ritz method. Based on the Lagrange method and the Newton Harmonic Balance (NHB) method, analytical approximate solutions in closed and explicit form are obtained. These approximate solutions show excellent agreement with those of numeric method for small as well as large amplitude. Moreover, due to brevity of expressions, the present analytical approximate solutions are convenient to investigate effects of various parameters on the large amplitude vibration response of tapered beams.

식품산업에서 활용되는 식품안전 분석기술의 현황 (Food safety analytical techniques used in food industry)

  • 김영준
    • 식품과학과 산업
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    • 제51권1호
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    • pp.16-25
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    • 2018
  • Recently, the importance of analytical techniques related to food safety is emerging in the food industry due to changes in diet patterns, environmental changes, climate change and consumer's interest in food safety. In particular, food safety accidents in the food industry may cause economic losses such as media reports, product recalls, consumer distrust, and so on. Therefore, a systematic, proactive and comprehensive food safety management system is increasingly required to prevent food safety issues. Efforts to ensure the reliability of food safety are essential by introducing various analysis instruments such as LC, GC, ICP, LC/MS/MS, GC/MS/MS, ICP/MS, PCR, and RT-PCR. In addition, recent food safety analytical techniques used in food industry should be shifted paradigm by developing multi-component simultaneous analytical method, low cost with high efficient analytical method, and eco-friendly method.

식품 중 다환방향족탄화수소 분석법 연구 (A study on analytical methods for polycyclic aromatic hydrocarbons in foods)

  • 김용연;신한승
    • 식품과학과 산업
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    • 제55권1호
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    • pp.45-57
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    • 2022
  • This study was proceeded the analytical methods using various analytical instruments for polycyclic aromatic hydrocarbons (PAHs) in food products. Various analytical methods were developed to determine levels of PAHs including benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene, and chrysene formed in various food products using gas chromatography-mass spectrometry (GC-MS), enzyme-linked immunosorbent assay (ELISA) and raman spectroscopy. Recently, the rapid on-site response for the detection of hazardous substances in food aims to develop an onsite rapid detection of a simplified technical analysis method to reduce the time and cost required for analysis of PAHs. Current PAHs detection methods have been reviewed along with new raman spectroscopy analytical method.

No-backlash characteristics analysis of a cycloidal ball planetary transmission under axial pre-tightening

  • Yang, Ronggang;Wang, Naige;Xiang, Jiawei
    • Structural Engineering and Mechanics
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    • 제81권4호
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    • pp.481-492
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    • 2022
  • Cycloidal ball planetary transmission (CBPT) has many applications as precision reducer, such as precision machinery and automation drive systems etc. The traditional analytical model of CBPT cannot accurately describe the change of the normal force of meshing points, and thus cannot describe the precise transmission process of meshing pairs. In the paper, a method for deriving the normal force equation is put forward by using the non-linear relationship between force and deformation in elastic mechanics. The two-point contact analytical models of all the meshing pairs are established to obtain the micro-displacement analytical model of CBPT under axial pre-tightening. Then, the non-real-time two-point contact analytical models of all the meshing pairs are further constructed to obtain the normal force expression to determine the critical compression coefficients. Experimental investigations are performed to verify the analytical model using the critical compression coefficients.

종형 구조물의 맥놀이 지도 작성법과 성덕대왕신종의 맥놀이 지도 (Beat Map Drawing Method of Bell Type Structures and Beat Maps of the King Seong-deok Divine Bell)

  • 김석현
    • 한국소음진동공학회논문집
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    • 제13권8호
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    • pp.626-636
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    • 2003
  • The beat distribution property of the King Seong-deok Divine Bell is investigated by experiment and analysis. The beat map method is proposed to explain the beat distribution property on the circumference of the bell. For the analytical investigation, an analytical model of the vibration beat is derived on a slightly asymmetric shell of revolution by using the modal expansion method. In the analytical method, the beat map can be drawn only if the modal parameters of the bell are obtained. The analytical beat model is applied to draw the beat map of the King Seong-deok Divine Bell. The validity of the analytical method is verified by comparing the analytical beat maps with the experimental results. This paper proposes a visualization method of the beat and theoretically identifies the reason why the clear and unclear beats repeat periodically along the circumference of the bell and how the striking position influences the beat distribution property.

정도관리용 포름알데히드 시료개발 및 분석능력평가 (Sample Development for Quality Control of Formaldehyde and Proficiency Analytical Testing)

  • 박해동;장미연;박승현
    • 한국산업보건학회지
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    • 제30권1호
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    • pp.58-66
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    • 2020
  • Objectives: The objective of this study was to develop formaldehyde samples for quality control (QC) and to test the applicability of proficiency analytical testing in Korea. Methods: We made formaldehyde samples with certified standard solutions (formaldehyde in water or acetonitrile) and 2,4-dinitrophenylhydrazine (2,4-DNPH)-coated silicagel tubes. Four levels of formaldehyde concentration were tested for storage stability at room temperature and at 4℃ over three months. Analytical proficiency testing was performed with four or 36 institutes. Results: Formaldehyde sample tubes were easily made through the injection of standard solutions and the average efficiencies of recovery were 95-101%. The coefficients of variation (CV) of the formaldehyde samples were 1.39-2.55%. The recovery efficiencies fell between 90% and 110% at the concentration range of 1-10 ㎍/sample over three months storage at refrigerated and room temperature. The CVs were less than 5% in the proficiency analytical testing. By adjusted proficient ranges, 64% of the results of the second proficiency analytical testing were acceptable. Conclusions: The formaldehyde samples made by injection on 2,4-DNPH-coated silicagel tubes were stable and applicable for quality control.