• 제목/요약/키워드: tolerances

검색결과 452건 처리시간 0.03초

BLDC 전동기에서 회전자 자석의 조립 공차에 따른 코깅토크 특성변화와 소음진동 불량 평가에 관한 연구 (A Study on Characteristic of Cogging Torque due to Assembly Tolerances of Magnet on Rotor and Evaluation of Noise and Vibration in Brushless DC Motor)

  • 윤승호;노승일;김희민;박관수
    • 한국자기학회지
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    • 제26권3호
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    • pp.86-91
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    • 2016
  • BLDC 전동기의 코깅토크는 영구자석과 철심의 상호작용에 의해 발생하고 소음과 진동을 발생시키는 요인이다. 제조 과정에서 조립 공차로 인해 영구자석이 회전자 철심 면에 제대로 붙지 않을 경우 BLDC 전동기의 전자기적 구조가 변할 수 있다. 본 논문에서는 조립 공차로 인해 자석이 회전자 표면과 분리되었을 때 코깅토크에 미치는 영향에 대해 연구했다. 핵심적인 설계 요소들인 회전자와 자석 간 분리, 분리를 가진 자석 수, 이웃한 자석들 간의 여러 배치형태를 고려했다. 코깅토크 해석을 위해 유한요소법을 사용하였고, 소음진동을 발생시키지 않는 조립 공차를 제안했다. 제안된 조립 공차로 제작된 BLDC 전동기의 코깅토크는 감소되었고 소음진동 또한 줄어들 것이라고 판단된다.

교잡어, 참돔 (Pagrus major, ♀) × 감성동 (Acanthopagrus schregeli, ♂)의 성장 및 수온변화와 저염분 환경에서의 내성 (Growth and Environmental Tolerances (Water Temperature and Low Salinity) of Hybrid Female Red Sea Bream Pagrus major × Male Black Sea Bream Acanthopagrus schregeli)

  • 김양수;지승철;;;정관식
    • 한국수산과학회지
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    • 제44권3호
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    • pp.276-283
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    • 2011
  • The growth and tolerance for water temperature and salinity were compared among red sea bream Pagrus major (RSB) black sea bream Acanthopagrus schregeli (BSB) and their hybrid ($F_1$), female RSB ${\times}$ male BSB. The growth of the $F_1$ fish did not differ until 27 days after hatching (dAH), after which the most rapid growth was observed until approximately 300 dAH, followed by RSB and BSB. However, the RSB had out grown the $F_1$ fish by approximately 303 dAH. By 480 dAH, the RSB were largest, followed by the $F_1$ and BSB groups. The tolerances for high and low water temperature were significantly different for each species and growth stage. The largest tolerance spectrum was observed in the BSB group, and the tolerance spectrums gradually decreased with increasing final body weight. During the salinity tolerance trials, all of the species started to die following transfer into freshwater (0 psu). BSB showed the highest survival rate when kept in fresh water for an average of 29.9 hours, while the $F_1$ fish were more tolerant than the RSB fish. The fish were increasingly tolerant to fresh water and changes in water temperature as they grew, while the size of the temperature spectrum remained unchanged but shifted to a lower temperature range with growth. Our results demonstrate that $F_1$ performed well in terms of growth compared to parental fish, with higher temperature and salinity tolerances than RSB, and is thus suggested to be a suitable aquaculture species for Korea and northeast China.

FUZZY FAULT TREE ANALYSIS

  • Jang, Dae-Heung
    • 품질경영학회지
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    • 제20권1호
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    • pp.107-117
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    • 1992
  • Conventional fault tree analysis has several problems as the estimations and tolerances of the failure probability values. To overcome these problems, fuzzy concepts with natural language can be applied to conventional fault tree analysis. And, we propose the evaluation method of the imprecision of top/basic events and possibility importances of basic events.

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공차설계에 의한 플립칩 접합용 초음파 혼의 제작 비용 최적화 (Manufacturing Cost Optimization of Ultrasonic Horn for Flip-chip Bonding using Tolerance Design)

  • 김종혁;권원태;이수일
    • 한국정밀공학회지
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    • 제29권8호
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    • pp.879-886
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    • 2012
  • The ultrasonic horn used for bonding of flip chip has been designed to vibrate at a natural frequency. The ultrasonic horn must be manufactured accurately in physical terms, because the small change of mechanical properties may result in the significant change of natural frequency. Therefore, tight tolerance is inevitable to keep the natural frequency in acceptable range. However, since tightening of the tolerance increases the manufacturing cost significantly, trade-off between the cost and accuracy is necessary. In this research, an attempt was made to design the ultra sonic horn within acceptable natural frequency while the manufacturing cost was kept as low as possible. For this purpose, among the 18 tolerances of physical terms of the ultrasonic horn, the most important 4 factors were selected using Taguchi method. The equation to relate those main factors and the natural frequency was made using response surface method. Finally, optimal design scheme for minimum manufacturing cost without a loss of performance was determined using SQP method.

SCM415 스퍼기어의 침탄처리에 관한 연구 (A Study on the Carburizing Treatment of SCM415 Steel Spur Gear)

  • 안민주;안인효;류성기
    • 한국기계가공학회지
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    • 제10권1호
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    • pp.67-72
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    • 2011
  • The main objective of this paper is obtaining the optimal carburizing hours which impacts geometric tolerances, OPD(Over Pin Diameter), runout, hardness and fatigure strength of SCM415 spur gear. In order to observe the deformation of the gear, the circularity, squareness, OPD(Over Pin Diameter) and runout were measured at 3hour, 4hour and 5hour respectively. As the result, the 3hour situation is the best, which very similar with the 4hour one. Afterwards, with the purpose of getting the result of gear hardness, the surface hardness, maximum hardness and interior hardness were measured. The result is 5h situation is the best, and it's similar with 4hour one. At last, the fatigue tests have been done which receive the result that the 4h situation showed 9~12% fatigue strength improvement compared with the 3h and 5h ones. To sum up the results, the 4hour situation shows the best performance in accuracy, hardness and fatigue strength.

수질중 농약잔류 허용기준 설정을 위한 근거자료 (Information Resources for the Establishment of Tolerances on Pesticide Residues in Water Quality)

  • 이서래;김용화;이미경
    • 한국환경농학회지
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    • 제14권3호
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    • pp.351-373
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    • 1995
  • The objective of this paper is to present relevant information and data from domestic and foreign references and to propose legal standards on pesticide residues in order to mitigate the pesticide contamination in the water environment. Among 200 pesticide ingredients in use in Korea, items necessary for standard setting were selected and theoretical residue limits were computed. The results are summarized as follows. In advanced countries, drinking water standards are established on the basis of health index ADI and water intake, whereas standards for surface water are established temporarily on the basis of different parameters, inconsistent with different countries. Pesticide residue limits applicable in Korea were proposed for 24 pesticides in drinking water(health basis) and for 25 pesticides in surface water(ecotoxicological basis), as selected by risk priority. It was recommended to accumulate scientific data by persistent research efforts in order to maintain the justification of the pesticide residue limits in water and relevant research topics to be undertaken in future were proposed.

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