• Title/Summary/Keyword: PM Machines

검색결과 112건 처리시간 0.031초

쐐기 인자 결정 깊이에 관한 연구 (The Study of the Measurement Point for Wedge Factor)

  • 김현자;이병용;김계준;배훈식;최은경;장혜숙;안기정
    • 한국의학물리학회지:의학물리
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    • 제3권2호
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    • pp.13-22
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    • 1992
  • 쐐기 인자의 깊이 의존성 연구를 통하여 적절한 쐐기 인자 결정 깊이에 관한 연구를 하였다. 4 MV, 6MV, 10MV, 15MV (사용가속기 Varian, Siemens, Mitsubishi) 선종에 대하여 명목 쐐기 각도 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$, 쐐기를 사용하여, 깊이 변화에 따르는 쐐기 인자 변화를 살펴보았다. 적정 쐐기 인자 결정 깊이를 알아보기 위하여 서울중앙병원, 부산침례병원, 원주기독병원에서 1990. 1991. 12 사이에 쐐기를 이용하여 방사선 치료를 받은 환자중 무작위로 614명을 추출하여 사용 에너지별, 쐐기 각도별, 치료 깊이별 분석을 시도하였다. 전체 환자의 60% 이상이 8cm$\pm$2.5cm 깊이에서 치료를 받았다. 쐐기 인자를 선량 최대 깊이로 결정할 경우 모든 환자가 평균 2%(최대 4%)의 치료 오차를 갖게 된다. 그러나 8cm깊이를 쐐기 인자 결정 깊이로 할 경우 평균 0.5% 선량 오차 이내로(사용가속기 기종, 에너지, 쐐기 각도에 관계 없이 최대 오차 1.7% 이내) 정확한 치료를 받을 수 있음을 알았다. 따라서 쐐기 인자는 5-10cm(8cm) 깊이에서 결정되는 것이 합리적인 것을 알았다.

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음료용 폐자동판매기에서의 HFC-134a 사용 및 폐기단계 탈루배출계수 결정에 대한 연구 (Estimation of Fugitive Emission Factors of HFC-134a from Scrap Cold Drinking Vending Machine at Use- and Disposal-Phase)

  • 이영표;김의건;김승도;변석호;김혜림;박준호;이동원
    • 대한환경공학회지
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    • 제35권5호
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    • pp.350-355
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    • 2013
  • 본 연구는 음료용 자동판매기의 냉매인 HFC-134a의 사용 및 폐기단계 탈루배출특성을 파악코자 하는데 그 목적을 두고 있다. 국내 제품인 음료용 폐자동판매기 47대의 HFC-134a 냉매를 상업용 냉매 회수기를 사용 회수하였고, 잔류량을 측정하였다. 본 연구에서 개발한 사용단계 탈루배출모델은 1차 동역학에 기초한 것으로 탈루율은 잔류 냉매 압력 즉 잔류량에 비례한다는 가정을 도입 적용하였다. 음료용 폐자동판매기의 배출시점에서의 잔류량과 사용기간 정보를 활용하여 탈루배출계수를 간접적으로 $6.9{\pm}0.7$ %/yr으로 결정하였고 이는 1대당 연간 11.6 g의 HFC-134a가 배출되는 것에 해당된다. 한편 음료용 폐자동판매기 냉매 평균 잔류율은 $62.5{\pm}2.2%$이었으며, 이는 1대당 잠재 탈루량을 144.8 g으로 결정할 수 있다. 음료용 자동판매기에서 회수한 폐냉매 성분 분석 결과가 신냉매와 거의 유사하여 폐냉매의 재사용이 가능할 것으로 여겨진다. 그러나 냉매회수 과정에서 압축기 오일이 30% 정도 포함되기 때문에 냉매 재사용을 위해서는 오일 분리가 필요하다.

지르코니아 블록과 CAM 종류에 따른 코핑의 변연적합도와 기계적 특성 비교 (Comparison on marginal fitness and mechanical properties of copings with zirconia block and CAM type)

  • 정인성;전병욱;김원영;강재민
    • 대한치과기공학회지
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    • 제39권2호
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    • pp.75-82
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    • 2017
  • Purpose: This study provided the basic data for selection the zirconia block and CAM by means of marginal fitness observations, flexural strength test and hardness test. Methods: Three dental zirconia blocks(ABCera, NaturaZ, ST98) and two dental milling machines(CAD/CAM MS, DWX-50) were used in this study. Metal abutment(diameter 10 mm, height 5 mm, inclined angle $3^{\circ}$ taper, 1 mm chamfer margin) was fabricated by Ti customized abutment, and then zirconia copings were fabricated for each ten specimens. Silicone replica technique was used to observe the marginal fitness of cross-sections with a stereomicroscope at ${\times}50$ magnification. The dental zirconia blocks was cut into 10 pieces each having a size of $25mm{\times}5mm{\times}1mm$, and fabricated according to the manufacturer's instructions, and flexural strength was measured using a universal testing machine. For hardness test, a micro Vickers hardness tester was used as it was in the flexural strength test. Statistical analysis was performed by one way ANOVA and post-test was performed by Scheffe test. Results: For marginal fitness of bucco-lingual axial, ZU group($59.7{\pm}10.3{\mu}m$) was the lowest, followed by RA, ZA, ZD, RD, RU. For marginal fitness of mesio-distal axial, ZU group($59.3{\pm}10.2{\mu}m$) was the lowest, followed by RA, ZA, RD, ZD, RU. One-way ANOVA showed statistically significant difference between groups(p<0.05). For flexural strength, ABCera block($718.0{\pm}57.2MPa$) was the highest, followed by NaturaZ, ST98. For hardness, ABCera block($1550.3{\pm}19.8Hv$) was the highest, followed by ST98, NaturaZ. There was no significant difference in flexural strength and hardness between blocks(p>0.05). Conclusion: Based on the results of this study, the type of dental zirconia block did influence the marginal fitness, and all dental zirconia blocks are expected to be suitable for clinical application. The highest flexural strength and hardness were ABCera block, and no statistically significant difference was observed.

RG-MADS를 적용한 매입형 영구자석 동기전동기의 최적설계 (Optimal Design of Interior PM Synchronous Machines Using Randomly-Guided Mesh Adaptive Direct Search Algorithms)

  • 김광덕;이동수;정상용;김종욱;이철균
    • 전기학회논문지
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    • 제61권2호
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    • pp.216-222
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    • 2012
  • Newly proposed RG-MADS (Randomly Guided Mesh Adaptive Direct Search) has been applied to the optimal design of Interior Permanent Magnet Synchronous Motor (IPMSM) which has the distinctive features of magnetic saturation. RG-MADS, advanced from classical MADS algorithm, has the superiority in computational time and reliable convergence accuracy to the optimal solution, thus it is appropriate to the optimal design of IPMSM coupled with time-consuming Finite Element Analysis (FEA), necessary to the nonlinear magnetic application for better accuracy. Effectiveness of RG-MADS has been verified through the well-known benchmark-functions beforehand. In addition, the proposed RG-MADS has been applied to the optimal design of IPMSM aiming at maximizing the Maximum Torque Per Ampere (MTPA), which is regarded as representative design goal of IPMSM.

2상(相)8극영구자석형(極永久磁石形) LPM의 자기회로설계(磁氣回路設計)와 제어방식(制御方式)에 관한 연구(硏究) (A Study on the Magnetic Circuit Design and Control Method of 2-Phase 8-Pole PM Type Linear Pulse Motor)

  • 김일중;이은웅;이민명;이명일
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1991년도 하계학술대회 논문집
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    • pp.47-50
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    • 1991
  • LPM(Linear Pulse Motor) provide direct and precise position control of bidirectional linear motion. LPM is not subject to the same linear velocity and acceleration limitations inherent in systems converting rotary to linear motion such as lead screws, rack and pinion, belt and pulley drives. With LPM, all the thrust force generated by the motor is efficiently applied directly to the load. And speed, distance, and acceleration are easily programmed in a highly repeatable fashion. Potential industrial and application fields of LPM include PCB assembly, industrial sewing machines, automatic inspection, coil winder, medical uses, conveyer system, laser cut and trim systems, semiconductor wafer processing, OA instruments etc. This paper describes various design parameter of LPM such as magnetic ciucuit construction methods, phase number and tooth number per pole, permanent magnet and coil mmf, tooth geometries. And to solve the problems of existing control methods, in this paper, a new control method of the LPM is proposed throughout modern control theory.

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Phase Current Magnitude Variation Method to Reduce End-Effect Force of PM Linear Synchronous Motor

  • Kim, Min-Jae;Lim, Jae-Won;Yim, Woo-Gyong;Jung, Hyun-Kyo
    • Journal of Electrical Engineering and Technology
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    • 제6권6호
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    • pp.793-798
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    • 2011
  • Numerous methods are available for reducing the end-effect force of linear machines. Majority of these methods focus on redesigning the poles or slots. However, these methods require additional manufacturing cost and decrease the power density. The current paper introduces another approach to reduce the end-effect force. The new approach is a method of tuning the input phase current magnitudes individually. According to the proposed method, reduction of the end-effect force could be achieved without redesigning the poles/slots or attaching auxiliary poles/slots. The proposed method is especially applicable when the target motor is very expensive or will be used for a special mission, such as hauling army vehicles equipped with three single-phase inverters. The validity of the suggested method was exemplified by the finite element method with three-phase permanent-magnet linear synchronous motor.

A Novel Picometer Positioning System for Machine Tools and Measuring Machines

  • Mizumoto, Hiroshi;Yabuta, Yoshito;Arii, Shiroh;Tazoe, Yoichi;Kami, Yoshihiro
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2005년도 ICCAS
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    • pp.123-128
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    • 2005
  • A novel tri-mode ultraprecision positioning system for machine tools and measuring machine is proposed. The basic coarse mode uses a Twist-roller Friction Drive (abbr. TFD), and controls several tens of millimeters of the machine-table travel with nanometer order of positioning resolution. The fine mode also utilizes the TFD with a fine adjusting mechanism. The resolution of the fine mode is in the range of sub-nanometer. For realizing picometer positioning, the ultra-fine mode is executed by using an active aerostatic guideway. On the bearing surface of this active guideway, several Active Inherent Restrictors (abbr. AIRs) are embedded for controlling the table position. An AIR unit consists of a piezoelectric actuator having a through hole, one end of the hole on the bearing surface acts as an inherent restrictor. Owing to the aerostatic mechanism of the AIR, the deformation of the piezoelectric actuator in the AIR unit causes much reduced table displacement. Such motion reduction is effective for ultraprecision positioning. Current positioning resolution of the ultra-fine mode is 50pm, however the final goal of the positioning resolution is expected to be in the order of picometer.

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표면부착형 / 매입형 영구자석 동기 전동기의 비교 분석 (Comparative Analysis of Surface-mounted and Interior Permanent Magnet Synchronous Motor)

  • 박형일;김관호;신경훈;장석명;최장영
    • 전기학회논문지
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    • 제65권6호
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    • pp.987-994
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    • 2016
  • In this paper, we present a comparative analysis of surface-mounted permanent magnet synchronous motors (SPMSM) and interior permanent magnet synchronous motors (IPMSM). First, we use 2D finite element analysis (FEA) to analyze models satisfying the same rated conditions according to the torque-speed curve characteristics, which are determined from the operating conditions. Next, we manufacture an SPMSM and IPMSM having good performances from an electromagnetic perspective based on analysis results, namely the cogging torque, torque ripple, and efficiency. We analyze both of the manufactured machines when they are connected back-to-back and when they are used as a motor and a generator, respectively. The motor is driven by a commercial inverter and the generator is connected to a three-phase resistance load bank. Finally, based on experimental results, which include the total harmonic distortion (THD) of the back electro-motive force (EMF), cogging torque, efficiency, and mass, we determine the motor that is most suitable under requirements.

적층식 제조(Additive manufacturing) 기술동향 (Technology Trend of the additive Manufacturing (AM))

  • 오지원;나현웅;최한신
    • 한국분말재료학회지
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    • 제24권6호
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    • pp.494-507
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    • 2017
  • A three-dimensional physical part can be fabricated from a three-dimensional digital model in a layer-wise manner via additive manufacturing (AM) technology, which is different from the conventional subtractive manufacturing technology. Numerous studies have been conducted to take advantage of the AM opportunities to penetrate bespoke custom product markets, functional engineering part markets, volatile low-volume markets, and spare part markets. Nevertheless, materials issues, machines issues, product issues, and qualification/certification issues still prevent the AM technology from being extensively adopted in industries. The present study briefly reviews the standard classification, technological structures, industrial applications, technological advances, and qualification/certification activities of the AM technology. The economics, productivity, quality, and reliability of the AM technology should be further improved to pass through the technology adoption lifecycle of innovation technology. The AM technology is continuously evolving through the introduction of PM materials, hybridization of AM and conventional manufacturing technologies, adoption of process diagnostics and control systems, and enhanced standardization of the whole lifecycle qualification and certification methodology.

PMP 방식을 이용한 BGA 볼의 3차원 형상측정 시스템 (3-Dimensional Shape Measurement System for BGA Balls Using PMP Method)

  • 김효준;김준식;주효남
    • 제어로봇시스템학회논문지
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    • 제22권1호
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    • pp.59-65
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    • 2016
  • As modern electronic devices get smaller and smaller, high-resolution, large Field-Of-View (FOV), fast, and cost-effective 3-dimensional (3-D) measurement is requested more and more. In particular, defect inspection machines using machine-vision technology nowadays require 3-D inspection as well as the conventional 2-D inspection. Phase Measuring Profilometry (PMP) is one of the fast non-contact 3-D shape measuring methods currently being extensively investigated in the electronic component manufacturing industry. The PMP system is well known and is successfully applied to measuring complex surface profiles with varying reflectance properties. However, for highly reflective surfaces, such as Ball Grid Arrays (BGAs), it has difficulty accurately measuring 3-D shapes. In this paper, we propose a new fast optical system that can eliminate the highly reflective saturated regions in BGA ball images. This is achieved by utilizing four Low Intensity Grating (LIG) images together with the conventional High Intensity Grating (HIG) images. Extensive experiments using BGA samples show a repeatability of under ${\pm}20um$ in standard deviation, which is suitable for most 3-D shape measurements of BGAs.