• Title, Summary, Keyword: Accuracy improvement

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Cutting Condition Selection for Geometrical Accuracy Improvement in End Milling (엔드밀 가공에서 형상 정밀도 향상을 위한 절삭 조건 선정)

  • 류시형;최덕기;주종남
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1784-1788
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    • 2003
  • For the improvement of geometrical accuracy in end milling, cutting method and cutting condition selection are investigated in this paper. As machining processes are composed of several steps such as roughing, semi-finishing. and finishing, cutting forces and tool deflection are calculated considering surface shape generated by the previous cutting. The effects of tool teeth numbers, tool geometry, and cutting conditions on the form error are analyzed. Using the from error prediction method from tool deflection, cutting condition for geometrical accuracy improvement is discussed. The characteristics and the difference of generated surface shape in up and down milling are dealt with and over-cut free condition in up milling is presented. The form error reduction method by alternating up and down milling is also suggested. The effectiveness of the presented method is examined from a set of cutting tests under various cutting conditions. This research contributes to cutting process optimization for the geometrical accuracy improvement in die and mold manufacture.

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Accuracy Improvement of Boron Meter Adopting New Fitting Function and Multi-detector

  • Kong, Chidong;Lee, Hyunsuk;Tak, Taewoo;Lee, Deokjung;Kim, Si Hwan;Lyou, Seokjean
    • Nuclear Engineering and Technology
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    • v.48 no.6
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    • pp.1360-1367
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    • 2016
  • This paper introduces a boron meter with improved accuracy compared with other commercially available boron meters. Its design includes a new fitting function and a multi-detector. In pressurized water reactors (PWRs) in Korea, many boron meters have been used to continuously monitor boron concentration in reactor coolant. However, it is difficult to use the boron meters in practice because the measurement uncertainty is high. For this reason, there has been a strong demand for improvement in their accuracy. In this work, a boron meter evaluation model was developed, and two approaches were considered to improve the boron meter accuracy: the first approach uses a new fitting function and the second approach uses a multi-detector. With the new fitting function, the boron concentration error was decreased from 3.30 ppm to 0.73 ppm. With the multi-detector, the count signals were contaminated with noise such as field measurement data, and analyses were repeated 1,000 times to obtain average and standard deviations of the boron concentration errors. Finally, using the new fitting formulation and multi-detector together, the average error was decreased from 5.95 ppm to 1.83 ppm and its standard deviation was decreased from 0.64 ppm to 0.26 ppm. This result represents a great improvement of the boron meter accuracy.

A Study on 6 Edges Reamer for the Improvement of Accuracy of Automotive Cylinder Head Guide Pin (자동차 실린더헤드 가이드 핀의 정밀도 향상을 위한 6날 리머에 관한 연구)

  • Kim Hae-Ji;Kim Nam-Kyung
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.6
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    • pp.81-86
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    • 2004
  • Generally, automotive cylinder head is manufactured by FCD45 material that is hard to cutting materials, and it needs the accurate machining tool fir higher output of engine. This paper is concerned with a study on TiN coated 6 edges reamer for improving machining accuracy of cylinder head guide pin. The reamer shape is changed from 4 edges to 6 edges for the improvement of machining accuracy. Also, TiN coating is applied to the improvement of surface roughness of cylinder head guide pin and tool life of 6 edges reamer. It is noted that 6 edges reamer are effective in controlling the dimensional accuracy and surface roughness as well as increasing tool life.

Accuracy Improvement of Lattice Parameters Measured from Electron Diffraction Data (전자회절을 이용한 격자상수의 측정 정확도 향상)

  • Lee, Sang-Gil;Song, Kyung;Kim, Jin-Gyu
    • Applied Microscopy
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    • v.41 no.1
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    • pp.75-79
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    • 2011
  • For quantitative analysis of nano-crystal structure, we reported the accuracy improvement method of lattice parameters measured from electron diffraction. For calculation of Au lattice parameters used as a standard crystal structure, it was considered two different acquisition methods (detector and enegy-filter) and three different calculation methods (conventional, least-square and regression fit). As a result, the measurement reliability could be enhanced by using CCD camera which gives higher performance, while energy-filtering did not affect the improvement the camera constant accuracy. Also, the accuracy of lattice parameters could be improved up to $10^{-4}$ order by regression fitting with correction formula. Finally, it is expected that the combination of regression fitting and intensity extraction from energy-filtered precession electron diffraction gives a solution of quantitative structure analysis for unknown nano-crystals.

Effects of selection index coefficients that ignore reliability on economic weights and selection responses during practical selection

  • Togashi, Kenji;Adachi, Kazunori;Yasumori, Takanori;Kurogi, Kazuhito;Nozaki, Takayoshi;Onogi, Akio;Atagi, Yamato;Takahashi, Tsutomu
    • Asian-Australasian Journal of Animal Sciences
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    • v.31 no.1
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    • pp.19-25
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    • 2018
  • Objective: In practical breeding, selection is often performed by ignoring the accuracy of evaluations and applying economic weights directly to the selection index coefficients of genetically standardized traits. The denominator of the standardized component trait of estimated genetic evaluations in practical selection varies with its reliability. Whereas theoretical methods for calculating the selection index coefficients of genetically standardized traits account for this variation, practical selection ignores reliability and assumes that it is equal to unity for each trait. The purpose of this study was to clarify the effects of ignoring the accuracy of the standardized component trait in selection criteria on selection responses and economic weights in retrospect. Methods: Theoretical methods were presented accounting for reliability of estimated genetic evaluations for the selection index composed of genetically standardized traits. Results: Selection responses and economic weights in retrospect resulting from practical selection were greater than those resulting from theoretical selection accounting for reliability when the accuracy of the estimated breeding value (EBV) or genomically enhanced breeding value (GEBV) was lower than those of the other traits in the index, but the opposite occurred when the accuracy of the EBV or GEBV was greater than those of the other traits. This trend was more conspicuous for traits with low economic weights than for those with high weights. Conclusion: Failure of the practical index to account for reliability yielded economic weights in retrospect that differed from those obtained with the theoretical index. Our results indicated that practical indices that ignore reliability delay genetic improvement. Therefore, selection practices need to account for reliability, especially when the reliabilities of the traits included in the index vary widely.

Image Separation Average Value Matching Method Development for Accuracy Improvement of Appearance Inspection (외관 검사의 정확도 향상을 위한 영상 분할 평균값 매칭 기법 개발)

  • Park, Se-Hyuk;Kang, Su-Min;Huh, Kyung-Moo
    • Proceedings of the KIEE Conference
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    • pp.445-446
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    • 2007
  • The goal of this paper is accuracy improvement of appearance inspection by using image separation average value matching method. The appearance inspection of various electronic products and parts has been executed by the eyesight of human. But inspection by eyesight can't bring about uniform inspection result. Because the appearance inspection result by eyesight of human is changed by condition of physical and spirit of the checker. So machine vision inspection system is currently used to many appearance inspection fields instead of the checker. However the inspection result of machine vision is changed by the illumination of workplace. Therefore we have used a average value matching in this paper for improvement of vision inspection accuracy and could increase inspection accuracy of vision system. In other words, we made an effort for elevation of vision inspection accuracy by making the identical image separation average value of reference image and input image. Also this system has been developed only using PC, CCD Camera and Visual C++ for universal workplace.

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A Study on Improvement of Finishing Accuracy Using 3-Axis Machine for Curved Surface Dies (3축 가공기를 이용한 곡면 금형의 연마 정밀도 향상에 관한 연구)

  • Lim, Dong-Jae;Lee, Sang-Jik;Jeong, Hae-Do
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.3
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    • pp.61-67
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    • 2001
  • The finishing process for die is an important process because it has influence on final quality of products. Recently s study on development of 5-axis die automated finishing machine has been progressed. But die must be moved from the cutting machine to the die automated finishing machine. So manufacturing cost and time increase and machining error occurs by transfer. So, in this study, a 3-axis machining center was applied to die finishing. Because cutting tool can be changed to finishing tool by ATC, both of cutting and finishing process are possible on the machine. However, this application results in the decrease of finishing for the improvement of form accuracy. So this study focused on the generation of finishing tool path suitable to 3-axis die finishing for the improvement of form accuracy. The form accuracy evaluation is performed by the measurement of removal depth using a stylus profilometer. From the result, it is confirmed that form accuracy was improved less than 2$\mu$m of removal depth error.

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A Sutdy on Improvement of Geomeric Accuracy by using Fuzzy Algorithm in Surface Grinding (퍼지 알고리즘을 이용한 평면연삭의 형상정도 향상에 관한 연구)

  • 천우진;김남경;하만경;송지복
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.149-154
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    • 1993
  • In heavy grinding that is on of the high efficient grinding method, meaningful deformation is generated by high temperature. So, after machining, geomeric error generated od the workpiece. The most important factor on the geometric error is temperature difference between upper layer and lower layer (T $_{d}$) . Relations between Td and grinding condition and maximum geometric error and grinding condition are obtained by experiment. This relations are used in fuzzy algorithm for improvement geometric accuracy. The main results are follows : (1) The linear relation between maximum geometric error and grinding condition is ovtained by experiment. (2) The linear relation between maximum temperature difference between upper layer and lower layer and grinding condition is ovtained by experiment. (3) Control peth of wheel for improvement geometric accuracy is obtained by using the fuzzy algorithm.m.

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Improvement of an Automatic Segmentation for TTS Using Voiced/Unvoiced/Silence Information (유/무성/묵음 정보를 이용한 TTS용 자동음소분할기 성능향상)

  • Kim Min-Je;Lee Jung-Chul;Kim Jong-Jin
    • MALSORI
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    • no.58
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    • pp.67-81
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    • 2006
  • For a large corpus of time-aligned data, HMM based approaches are most widely used for automatic segmentation, providing a consistent and accurate phone labeling scheme. There are two methods for training in HMM. Flat starting method has a property that human interference is minimized but it has low accuracy. Bootstrap method has a high accuracy, but it has a defect that manual segmentation is required In this paper, a new algorithm is proposed to minimize manual work and to improve the performance of automatic segmentation. At first phase, voiced, unvoiced and silence classification is performed for each speech data frame. At second phase, the phoneme sequence is aligned dynamically to the voiced/unvoiced/silence sequence according to the acoustic phonetic rules. Finally, using these segmented speech data as a bootstrap, phoneme model parameters based on HMM are trained. For the performance test, hand labeled ETRI speech DB was used. The experiment results showed that our algorithm achieved 10% improvement of segmentation accuracy within 20 ms tolerable error range. Especially for the unvoiced consonants, it showed 30% improvement.

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