• Title/Summary/Keyword: Uniformity index

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A Preliminary Study for Quantifying Appearance Assessment of Assembly Seam Gaps - Case Study of Drawer Assembly (조립품 심(seam)의 갭(gap)에 대한 정량적 심미평가의 기초연구 - 서랍장을 대상으로 한 사례연구)

  • Lee, Hae-Seung;Lee, Rae-Woo;Yim, Hyun-June
    • Korean Journal of Computational Design and Engineering
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    • v.16 no.5
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    • pp.380-389
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    • 2011
  • Esthetic appeal of a product is often affected by the appearance quality of seams forming between components of the product. The appearance quality of seams is, however, assessed in a very subjective and qualitative manner that heavily depends on the evaluator. This paper presents a preliminary study to quantify such assessment by formulating a quantitative index which is a linear function of the seam gap sizes, seam gap ranges, and the size uniformity of seam gaps. By considering a highly simplified problem of a drawer system and utilizing subjective assessments by twenty evaluators, the index has been formulated. The validity of this index has been confirmed by observing its behavior with changes of the component tolerances. Also, the utility of this index has been demonstrated through a selective assembly scheme applied to the drawer system problem. Though the index formulated in this study for seam appearance quality may be useful, future studies are necessary to make the model readily applicable to real problems.

Analysis of an internal flow with multi-perforated tube geometry in an integrated Urea-SCR muffler (다공튜브 형상변화에 따른 촉매 삽입형 Urea-SCR 머플러 내부유동 해석)

  • Moon, Namsoo;Lee, Sangkyoo;Lee, Jeekeun
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.5
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    • pp.500-509
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    • 2013
  • This study reports a numerical analysis of the internal flow characteristics of the integrated urea-SCR muffler system with the various geometries of the multi-perforated tube which is set up between the muffler inlet and in front of SCR catalysts. The multi-perforated tube is generally used to disperse uniformly the urea-water solution spray and to make better use of the SCR catalyst, resulting in the increased $NO_x$ reduction and decreased ammonia slip. The effects of the multi-perforated tube orifice area ratios on the velocity distributions in front of the SCR catalyst, which is ultimately quantified as the uniformity index, were investigated for the optimal muffler system design. The steady flow model was applied by using a general-purpose commercial software package. The air at the room temperature was used as a working fluid, instead of the exhaust gas and urea-water solution spray mixture. From the analysis results, it was clarified that the multi-perforated tube geometry sensitively affected to the formation of the bulk swirling motion inside the plenum chamber set in front of the SCR catalyst and to the uniformity index of the velocity distribution produced at the inlet of the catalyst.

A Study on Non-uniformity Correction Method through Uniform Area Detection Using KOMPSAT-3 Side-Slider Image (사이드 슬리더 촬영 기반 KOMPSAT-3 위성 영상의 균일 영역 검출을 통한 비균일 보정 기법 연구 양식)

  • Kim, Hyun-ho;Seo, Doochun;Jung, JaeHeon;Kim, Yongwoo
    • Korean Journal of Remote Sensing
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    • v.37 no.5_1
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    • pp.1013-1027
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    • 2021
  • Images taken with KOMPSAT-3 have additional NIR and PAN bands, as well as RGB regions of the visible ray band, compared to imagestaken with a standard camera. Furthermore, electrical and optical properties must be considered because a wide radius area of approximately 17 km or more is photographed at an altitude of 685 km above the ground. In other words, the camera sensor of KOMPSAT-3 is distorted by each CCD pixel, characteristics of each band,sensitivity and time-dependent change, CCD geometry. In order to solve the distortion, correction of the sensors is essential. In this paper, we propose a method for detecting uniform regions in side-slider-based KOMPSAT-3 images using segment-based noise analysis. After detecting a uniform area with the corresponding algorithm, a correction table was created for each sensor to apply the non-uniformity correction algorithm, and satellite image correction was performed using the created correction table. As a result, the proposed method reduced the distortion of the satellite image,such as vertical noise, compared to the conventional method. The relative radiation accuracy index, which is an index based on mean square error (RA) and an index based on absolute error (RE), wasfound to have a comparative advantage of 0.3 percent and 0.15 percent, respectively, over the conventional method.

Optimization of Optical Structure of Lightguide Panel for Uniformity Improvement of Edge-lit Backlight (엣지형 LED 백라이트의 균일도 향상을 위한 도광판의 광구조 최적화)

  • Lee, Jung-Ho;Nahm, Kie-Bong;Ko, Jae-Hyeon;Kim, Joong-Hyun
    • Korean Journal of Optics and Photonics
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    • v.21 no.2
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    • pp.61-68
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    • 2010
  • Optical simulation methods were applied to the edge-lit LED backlight for LCD TV applications in order to optimize the optical structure of the light guide plate(LGP), and thus to improve the uniformity properties by removing the bright spots caused by LED's. The edge-lit LED backlight consisted of three white LED's with a lamp cover, a light guide plate, and a reflection film. When there was no pattern on the entrance side surface of the LGP, the illuminance uniformity was sensitively dependent on the distance d between the LED and the entrance surface. The illuminance uniformity increased with d but its increasing rate slowed down when d was beyond ~ 1.5 mm. When micro-patterns such as a lenticular lens array (LLA) or a serration pattern were formed on the entrance surface, the illuminance uniformity was improved substantially even for the case of very small d. At the same simulation condition, the lightguide with serration pattern showed a better uniformity than that with LLA pattern. Additional improvement could be achieved by changing the refractive index of the micro-patterns. These results suggest that using micro-patterns is a very effective way to reduce the bright spots due to their refracting function for the concentrated incident rays onto the LGP.

Effect of grating structures and mirror postions on characteristics of 1.55$\mu\textrm{m}$ DFB lasers-II (1.55.$\mu\textrm{m}$ DFB 레이저의 특성에 미치는 Grating 구조와 Mirror 위치의 영향 -II)

  • Kwon, Kee-Young
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.2
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    • pp.48-56
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    • 1995
  • The operating characteristics, such as, the threshold gain, lasing frequency, and longitudinal intensity profile, etc., of 1.55$\mu$m DFB laser diode with index and/or gain grating structures and with one side AR-coated mirror have been analyzed. From this analysis, the optimum design parameters have been shown that ${\Delta}{\Omega}$ (the phase difference between index grating and gain grating) is 0 or ${\pi}$, (xL)$_{r}$=1~3 and (xL)$_{i}$=0.5~0.9. It has been also shown that the modal selectivity and intensity uniformity of the DFB lasers with .DELTA..OMEGA.=0 are ~1.2 times better thatn those of the DFB lasers with ${\Delta}{\Omega}$= ${\pi}$.

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Application of Analytic Hierarchy Process for the Selection of Cotton Fibers

  • Majumdar Abhijit;Sarkar Bijan;Majumdar Prabal Kumar
    • Fibers and Polymers
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    • v.5 no.4
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    • pp.297-302
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    • 2004
  • In many engineering applications, the final decision is based on the evaluation of a number of alternatives in terms of a number of criteria. This problem may become very intricate when the selection criteria are expressed in terms of different units or the pertinent data are difficult to be quantified. The Analytic Hierarchy Process (AHP) is an effective way in dealing with such kind of complicated problems. Cotton fiber is selected or graded, in the spinning industries, based on several quality criteria. However, the existing selection or grading method based on Fiber quality Index (FqI) is rather crude and ambiguous. This paper presents a novel approach of cotton fiber selection using the AHP methodology of Multi Criteria Decision Making.

Study on the Soil Compaction (Part 4) -The Influence of Soil Compadtion on Unconfined Compressive Strength and Coefficient of Permeability- (흙의 다짐에 관한 연구(제4보) -흙의 다짐이 -축골조강동 및 투수계수에 미치는 영향-)

  • 강예묵
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.12 no.3
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    • pp.2003-2012
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    • 1970
  • In order to the influence of grain size distribution on compressive strength and coefficient of permeability, unconfined compression test and permeability test were performed for seventy samples that have various grain-size distributions. Its results are as follows: 1. Maximum unconfined compressive strength appears at the dry side of optimum moisture content. 2. Unconfined compressive strength is proportional to the increase of percent passing of No. 200 sieve. 3. Precent of deformation in failure increases in proportion to the increase of percent passing of No. 200 sieve, and modulus of No. 200 sieve, and modulus of deformation also increases in proportion to percent passing of No. 200 sieve. 4. Unconfined compressive strength increases in proportion to uniformity coefficient, liquid limit and plastic index, but it decreases gradually according to the increase of coefficient of grading and classification area. 5. Maximum dry density decreases according to the increase of void ratio. 6. Coefficient of permeability decreases according to the increase of percent passing of No. 200 sieve, and when percent of No. 200 sieve, and when percent passing of No. 200 enlarged more than 40%, it becomes less than $10^{-6}cm/sec$ which is the limit of coefficient of permeability of core material for earth dam proposed by Lee. 7. Coefficient of permeability increases according to the increase of coefficient of grading, classification area and index of Talbot formula r, but it was rather decrease by the increase of uniformity coefficient. 8. Coefficient of permeability seems to depend on the size and the shape of the flow path which is a series of void to be concerned by the size and the proprton of soil grain, even though void ratios are same.

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An Estimate of Image Quality and Radiation Doses of Coronary Artery in MDCT Using Prospective and Retrospective ECG Gating Scan Mode (MDCT 관상동맥 조영 검사에서 전향적 동조화 및 후향적 동조화 기법의 화질과 선량 관계)

  • Oh, Jong-Kap
    • Journal of radiological science and technology
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    • v.34 no.4
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    • pp.315-321
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    • 2011
  • The goal of this study is to reduce patient exposure dose by providing image quality and radiation dose according to inspection methods. Volume Computed Tomography Dose Index(CTDIvol) and Dose Length Product(DLP) of prospective and retrospective ECG gating snapshot segment of Coronary CT angiography(CTA) were measured each snapshot segment methods. CT number, noise, uniformity, and resolution were also measured using phantom under the same condition of coronary CTA. The results showed that CT number, noise, uniformity and resolution are similar to each other. In terms of CTDIvol and DLP, however, measurement dose of prospective ECG gating snapshot segment was lower than the retrospective case by 37.5% and 40.3%. Therefore, it is highly recommended that in the coronary CTA, prospective ECG gating scan mode should be chosen to reduce patient dose.

Effects of Mulberry Leaves Powders on the Quality Characteristics of Yellow Layer Cakes (뽕잎분말을 첨가한 옐로우 레이어 케이크의 품질특성)

  • Kim, Yeoung-Ae
    • Korean Journal of Food Science and Technology
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    • v.35 no.5
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    • pp.871-876
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    • 2003
  • Yellow layer cakes were prepared with flour that was partially substituted with mulberry leaf powder (at the levels of 4, 8, 12, 16 and 20%). Batter viscosity increased with increasing substitution levels while specific gravity decreased. The specific volume of the cake increased as batter viscosity increased, except at 20% substitution. Substituting mulberry leaf powder for flour also resulted in decreased lightness and yellowness and increased redness of the cake crumbs. The volume index and uniformity index were not influenced by the addition of mulberry leaf powder, while the symmetry indexes of cakes with 16% and 20% powder were lower than the control. The hardness of cakes substituted with mulberry leaf powder was lower than that of the control during 10 days of storage. Sensory characteristics, including cell size and cell uniformity, were adversely affected with substitution levels of 16% and 20%. The addition of mulberry leaf powder did not influence softness, but affected moistness significantly.

Study on NOx Reduction with Multi-Perforated Tube Geometry in Integrated Urea-SCR Muffler (촉매삽입형 Urea-SCR 머플러 다공튜브 형상변화에 따른 NOx 저감 특성에 관한 연구)

  • Moon, Namsoo;Lee, Sangkyoo;Ko, Sangchul;Lee, Jeekeun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.12
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    • pp.1017-1026
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    • 2014
  • A multi-perforated tube is generally installed between the muffler inlet and in front of selective catalytic reduction (SCR) catalysts in the integrated urea-SCR muffler system in order to disperse the urea-water solution spray uniformly and to make better use of the SCR catalyst, which would result in an increase nitrogen oxide ($NO_x$) reduction efficiency and a decrease in the ammonia slip. The effects of the multi-perforated tube orifice area ratios on the internal flow characteristics were investigated analytically by using a general-purpose commercial software package. From the results, it was clarified that the multi-perforated tube geometry sensitively affected the generation of the bulk swirling motion inside the plenum chamber set in front of the SCR catalyst and to the uniformity index of the velocity distribution produced at the inlet of the catalyst. To verify the analytical results, engine tests were carried out in the ESC and ETC modes. Results of these tests indicated that the larger flow model in the longitudinal direction showed the highest NOx reduction efficiency, which was a good agreement with the analytical results.