• Title/Summary/Keyword: Spot size

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Design of Spot - Size Converter for optical network (광 네트워크 용 Spot - Size Converter 설계 최적화 설계)

  • Seok, Jae-Hyuk;Kim, Eung-Soo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.3
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    • pp.573-578
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    • 2012
  • The simplified spot-size convert for optical network has been suggested. We have analyzed the mode field distribution and optimized the spot-size converter using beam propagation method. The designed structure was consisted of straight waveguide and taper waveguide using polymer. The efficiency of the designed spot-size converter was over 99%.

Development of Measurement mechanism of Laser Beam Spot size for Industrial SFF system (산업용 SFF 시스템에서 Laser Beam Spot size 측정 메커니즘 개발)

  • Bae, Sung-Woo;Kim, Dong-Soo;Choi, Kyung-Hyun
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1383-1388
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    • 2007
  • Accuracy and processing time are very important factors when the desired shape is fabricated with Selective Laser Sintering (SLS), one of Solid Freeform Fabrication (SFF) systems. In a conventional SLS process, laser spot size is fixed during laser exposing on the sliced figure. Therefore, it is difficult to accurately and rapidly fabricate the desired shape. In this paper, to deal with those problems an SFF system having ability of changing spot size is developed. The system provides high accuracy and optimal processing time. Specifically, a variable beam expander is employed to adjust spot size for different figures on a sliced shape. Finally, Design and performance estimation of the SFF system employing a variable beam expander are achieved and the mechanism will be addressed to measure the real spot size generated from the variable beam expander.

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A STUDY OF THE RESOLUTION OF DENTAL INTRAORAL X-RAY MACHINES (치과 구내 X-선 촬영기의 사용연한에 따른 해상능에 관한 연구)

  • Kim Seon Ju;Chung Hyon De
    • Journal of Korean Academy of Oral and Maxillofacial Radiology
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    • v.20 no.2
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    • pp.289-297
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    • 1990
  • The purpose of this study was to assess the resolution and focal spot size of dental X-ray machines. Fifty dental X-ray machines were selected for measuring resolution and focal spot size. These machines were used in general dental clinics. The time of installation of the X-ray machine varies from 1 year to 10 years. The resolution of these machines was measured with the test pattern. The focal spot size of these machines was measured with the star test pattern. The following results were obtained: 1. The resolution of dental intraoral X-ray machines was not significantly changed in ten years. 2. The focal spot size of dental intraoral X-ray machines was not significantly increased in ten years. The statistical analysis between the mean focal spot size and nominal focal spot size was significant at the 0.05 level about the more than 3 years used machines.

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A Study of SPOT-Size Measurement in Single-mode Optical fibre (단일 모드 광섬유의 Spot Size 측정에 관한 연구)

  • 박호철;박한규
    • Proceedings of the Korean Institute of Communication Sciences Conference
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    • 1984.10a
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    • pp.22-24
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    • 1984
  • The mode spot size is a fundamental parameter of a single mode optical fibre which determines especially the spilces and the microbending loss. The spot-size measurement is recognised to be a useful mean to define the cut-off wavelength of single-mode fibres, ESI parameters and to predict the modal dispersion. To determine the ESI parameters, this paper is based on the use of a Ronchi ruling.

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ANALYSIS OF EFFECTIVE NUGGET SIZE BY INFRARED THERMOGRAPHY IN SPOT WELDMENT

  • Song, J.H.;Noh, H.G.;Akira, S.M.;Yu, H.S.;Kang, H.Y.;Yang, S.M.
    • International Journal of Automotive Technology
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    • v.5 no.1
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    • pp.55-59
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    • 2004
  • Spot welding is a very important and useful technology in fabrication of thin sheet structures such as the parts in an automobile. However, because the fatigue strength of the spot welding point is considerably lower than that of the base metal due to stress concentration at the nugget edge, the nugget size must be estimated to evaluate a reasonable fatigue strength at a spot welded lap joint. So far, many investigators have experimentally studied the estimation of fatigue strengths of various spot weldments by using a destructive method. However, these destructive methods poses problems so testing of weldments by these methods are difficult. Furthermore, these methods cannot be applied to a real product, and are time and cost consuming, as well. Therefore, there has been a strong, continual demand for the development of a nondestructive method for estimating nugget size. In this study, the effective nugget size in spot weldments have been analyzed by using thermoelastic stress analysis adopting infrared thermography. Using the results of the temperature distribution obtained by analysis of the infared stress due to adiabatic heat expansion under sinusoidal wave stresses, the effective nugget size in spot welded specimens were estimated. To examine the evaluated effective nugget size in spot weldments, it was compared with the results of microstructure observation from a 5% Nital etching test.

Effect of the Incident Optical Spot Size Upon the Quadrant Photodetector on the Optical Displacement Detection Sensitivity (4분할 광 검출기 상의 광점 크기가 변위 측정감도에 미치는 영향)

  • Lee, Eun-Joong;Lee, Jin-Woo;Kouh, Tae-Joon
    • Journal of the Korean Magnetics Society
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    • v.18 no.2
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    • pp.71-74
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    • 2008
  • In this paper, we have measured the effect of the optical spot size, incident upon the quadrant photodetector, on the optical displacement sensitivity of the optical beam deflection technique. We have built an optical displacement detection system based on the optical beam deflection method using 3 mW He-Ne laser and measured the displacement sensitivity with changing the optical spot size on the quadrant photodetector. We have also calculated the changes in the optical displacement sensitivity as a function of the incident laser spot size by modeling a circular optical spot with constant laser intensity. Our experimental and theoretical studies show that the optical displacement sensitivity increases with the decrease in the optical spot size. This suggests that in the design of the optical motion detection systems with sub-nanometer sensitivity, the displacement sensitivity can be optimized by reducing the size of the incident optical spot on the detector.

A Measurement of Size of the Open Crack using Ultrasound Thermography (초음파 서모그라피를 이용한 개방 균열의 크기 측정)

  • Cho, Jai-Wan;Seo, Yong-Chil;Jung, Seung-Ho;Jung, Hyun-Kyu;Kim, Seung-Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.3
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    • pp.218-223
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    • 2007
  • The dissipation of high-power ultrasonic energy at the faces of the defect causes an increase in temperature. It is resulted from localized selective heating in the vicinity of cracks because of the friction effect. In this paper the measurement of size and direction of crack using UET(Ultrasound Excitation Thermography) is described. The ultrasonic pulse energy is injected into the sample in one side. The hot spot, which is a small area around the crack tip and heated up highly, is observed. The hot spot, which is estimated as the starting point of the crack, is seen in the nearest position from the ultrasonic excitation point. Another ultrasonic pulse energy is injected into the sample in the opposite side. The hot spot, the ending point of the crack, is seen in the closest distance from the injection point also. From the calculation of the coordinates of both the first hot spot and the second hot spot observed, the size and slope of the crack is estimated. In the experiment of STS fatigue crack specimen(thickness 14mm), the size and the direction of the crack was measured.

Sweet Spot Analysis of Linear Array System with a Large Number of Loudspeakers by Geometrical Approach Method (다수의 스피커를 사용하는 선형 배열 시스템에서 기하학적 접근 방법을 통한 스윗 스팟 분석)

  • Yang, Hunmin;Park, Youngjin;Park, Youn-Sik
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.11
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    • pp.951-956
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    • 2013
  • This paper describes techniques used to analyze the sweet spot of sound field reproduced by ear-level linear arrays of loudspeakers by geometrical approach method. Previous researches have introduced various sweet spot definitions in their own way. In general, sweet spot is defined as an area whose stereophonic sound effect is valid. Its size is affected by the geometrical arrangement of the system. In this paper, a case when plane waves are generated by linear arrays of loudspeakers in the horizontal plane is considered. So the sweet spot is defined as an area in which the listener can perceive the desired azimuth angle. Because there are many loudspeakers, impulse responses at listener's ears are in the form of pulse-train and the time-duration of the pulse-train affects the localization performance of the listener. So we calculated the maximum time duration of pulse-train by geometrical approach method and identified with the results of impulse response simulation. This paper also includes parameter analysis with respect to aperture size, so it suggests a tool for sound engineers to expect the sweet spot size and listener's sound perception.

A Study on the Resistance Spot Welding of Aluminum Alloy (I) (알루미늄 합금의 저항점 용접에 관한 연구 ( I ))

  • 김상필;홍태민;장희석
    • Journal of Welding and Joining
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    • v.12 no.4
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    • pp.127-140
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    • 1994
  • Resistance spot welding has been widely used in the sheet metal joining processes because of its high productivity and convenience. In the resistance spot welding processes the size of molten nugget is a criterion to assess weld quality. Many research have founded on measuring weld nugget size at the same time monitoring welding process parameters such as dynamic resistance and electrode movement. With increasing demand of energy saving, many efforts were made to employ aluminum alloys that are lighter than steel and have relatively equivalent strength to steel in the automobile industry. In this paper, spot weldability of aluminum alloys for various welding conditions were examined by series of experiments. One of the 6000 series (Mg-Si) aluminum alloy, 6383-T4 was chosen, which is currently considered as a substitute for the galvanized steel. Dynamic resistance, electrode movement and corresponding nugget size were observed and compared to the case of steel. Finally, resistance spot welding of dissimilar material (galvanized steel-aluminum alloy) was attempted.

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