• 제목/요약/키워드: Golden Ratio

검색결과 101건 처리시간 0.022초

난류열전달 증진을 위한 리브형상의 수치최적화 (Numerical Optimization of Rib Shape to Enhance Turbulent Heat Transfer)

  • 김선수;김광용
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집B
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    • pp.304-308
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    • 2000
  • This paper presents a numerical optimization method to design geometric shape of streamwise periodic ribs mounted on one of the principal walls to enhance turbulent heat transfer in a rectangular channel flow. The golden section method is used for the one dimensional search. The optimization is based on Wavier-Stokes analysis of turbulent forced convection with $k-{\varepsilon}$ turbulence model. The width-to-height ratio of a rib is chosen as a design variable. The object function is defined as an inverse of average Nusselt number. An optimum shape of the rib has been obtained with reasonable computing time.

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고려청자(高麗靑磁)의 형태분석(形態分析) (매병(梅甁)의 균제성(均齊性) 연구(硏究)) (Analysis of the Koryo Celadon Shape (The Symmetry Study on the Maebyong))

  • 한상목;남인탁
    • 산업기술연구
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    • 제1권
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    • pp.39-45
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    • 1981
  • The typical characteristic shape of the Koryo inlaid celadon Maebyong was reviewed and the symmetry of S curve was analyzed by the method of geometric basis. The contours of Maebyongs sampled were drawn and divided with geometric rectangular proportion. The analytical results showed the static and dynamic symmetric of the vase and the ratios of height and base of the rectangles established for the analysis of their shapes were almost 1:1, 1:${\sqrt{2}}$ and 3:5(known as the Golden Ratio). The excellent beauty of the curve was principally caused by the balanced and harmonius division of the proportional rectangles. The contour line was developed along with the logarithmic spiral modified and introduced lately into the shape of Yi dynasty's liquor bottle.

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축류송풍기 설계를 위한 최적설계기법의 평가 (Assessment of Optimization Methods for Design of Axial-Flow Fan)

  • 최재호;김광용
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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    • pp.221-226
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    • 1999
  • Three-dimensional flow analysis and numerical optimization methods are presented for the design of an axial-flow fan. Steady, Incompressible, three-dimensional Reynolds-averaged Wavier-Stokes equations are used as governing equations, and standard k-$\epsilon$ turbulence model is chosen as a turbulence model. Governing equations are discretized using finite volume method. Steepest descent method, conjugate gradient method and BFGS method are compared to determine the searching directions. Golden section method and quadratic fit-sectioning method are tested for one dimensional search. Objective function is defined as a ratio of generation rate of the turbulent kinetic energy to pressure head. Sweep angle distributions are used as design variables.

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Function Optimization Using Quadratically Convergent Algorithms With One Dimensional Search Schemes

  • Kim, Do-Il
    • 대한산업공학회지
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    • 제14권2호
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    • pp.25-40
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    • 1988
  • In this paper, a unified method to construct a quadratically convergent algorithm with one dimensional search schemes is described. With this method, a generalized algorithm is derived. As it's particular cases, three quadratically convergent algorithms are performed. They are the rank-one algorithm (Algorithm I), projection algorithm (Algorithm II) and the Fletcher-Reeves algorithm (Algorithm III). As one-dimensional search schemes, the golden-ratio method and dichotomous search are used. Additionally, their computer programming is developed for actual application. The use of this program is provided with the explanation of how to use it, the illustrative examples that are both quadratic and nonquadratic problems and their output. Finally, from the computer output, each algorithm was analyzed from the standpoint of efficiency for performance.

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Natural Dyeing Using Tea Extract II - The Effect of Dyeing Condition on Dyeing Characteristics of Coffee Extract Dyed Silk Farbic-

  • Yoo, Hyun-Geun;Kim, Sin-Hee
    • 패션비즈니스
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    • 제10권3호
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    • pp.78-86
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    • 2006
  • Coffee extract dyeing on silk fabric using various mordanting agents at different mordanting condition was studied in our previous research. Coffee extract dyeing can exert beautiful colors and have several advantages over the conventional natural dyeing. Since most of natural dyes are expensive for mass production, strongly season and source dependent, and hard to store, and therefore, coffee waste was used as natural dye to create beautiful colors in this study. Coffee waste is inexpensive and easy to store, and provide a comparatively regular quality regardless of season and source. The effects of dyeing condition such as dyeing temperature, dyeing time, and liquor ratio on dyeing characteristics of silk fabrics were investigated. Coffee extract dyed silk showed brilliant colors, and the colors were different with the kind of mordant. Cu, Sn, and Al mordanted silks showed golden yellow with subtle change of hue and value, while Fe mordanted silk showed a brownish green color upon coffee extract dyeing. As the dyeing temperature increased, the dyeability generally increased in all mordanted silk fabrics except Fe mordanted silk until $45^{\circ}C$. The dyeing temperature did not affect the dyeability of Fe mordanted silk fabric. As the liquor ratio increased, the dyeability showed a gradual increase in all mordanted silk except Cu mordanted silk. Cu mordanted silk fabric showed an abrupt increase in dyeability at liquor ratio1:150. The dyeing time effect can be separated into 2 stages. During the initial half an hour, the dyeability did not change significantly, and then, increased after 45 min. dyeing time duration. A further increase in dyeing time after 45 min. did not affect the dyeing efficiency in all mordanted silk fabrics except the Cu mordanted.

수크령 파종량에 따른 주요녹화식물의 혼파가 비탈면 녹화에 미치는 영향 (Effects of Mixed Seeding of Main Revegetation Plants Treated with Different Seeding Amounts of Pennisetum alopecuroides on Cut-Slope Revegetation)

  • 함경식;심상렬
    • 한국환경복원기술학회지
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    • 제18권1호
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    • pp.25-35
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    • 2015
  • Pennisetum aloperculoides is a key revegetation species mixed with other plants species and used for revegetating cut-slopes. The purpose of this research is to identify the effects of mixed seeding of revegetation plants on cut-slope revegetation with respect to the quantity of Pennisetum aloperculoides seeds. The coverage ratio and appearance frequency of Pennisetum aloperculoides, and other revegetation species were measured to assess the cut-slope revegetation. We divided Pennisetum treatments into four groups with different Pennisetum seed quantities of $0g/m^2$, $5g/m^2$, $10g/m^2$, and $15g/m^2$. For each treatment group, we mixed identical quantities of seeds from herbaceous flowers (bird's-boot trefoil, aster, chrysanthemums, golden coreopsis and china pink), cool-season turfgrasses, and woody plants (korean lespedeza, indigo and silk tree). The increase in the quantity of the Pennisetum seeds resulted in the higher coverage ratio for Pennisetum, but in the lower coverage ratio for herbaceous flowers, cool-season turfgrasses, and woody plants. We observed a short-term succession process in which the dominant species shifted in the following order: the initial species Pennisetum, herbaceous flowers, and then lastly woody plants. In case of the appearance frequency, we also observed the higher appearance frequency for Pennisetum and the lower appearance frequency for the other plants due to the increase in the quantity of Pennisetum seeds. Pennisetum, bird's-foot trefoil and china pink showed the tendency to decrease the appearance frequency from one month after seeding while cool-season turfgrasses became extinct due to summer drought. In the woody plants, the appearance frequencies of korean lespedeza and indigo were high due to the decrease in quantity of Pennisetum seeds. The silk trees were damaged from winter frost and none emerged at all in 2013 (the following year after the seeding). Korean lespedeza and indigo appeared to have the short-term rapid dominance over other treated revegetation plants.

그리스 스타일의 미적 특성 (Aesthetic Characteristics of Grecian Style)

  • 함연자
    • 한국의류산업학회지
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    • 제9권6호
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    • pp.595-602
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    • 2007
  • This study examined the aesthetic characteristics of Grecian style which is being considered as the representative classic of Western fashion and the transformations of those Grecian styles on the fashion of the twentieth century. This study used positive research method using literatures on art history and clothing history, fashion related publications, and magazines and websites to understand the trend of fashion designer's collections. The study results are as follows. The aesthetic characteristics of Grecian style was considered to be the ideal beauty combined with symmetry, the functional beauty combined with non-construction, and the sensual beauty combined with natural body. The ideal beauty combined with symmetry appears as a style that shows idealistic proportion of a body emphasizing high-waist based on the golden ratio and the body as a whole rather than details. The functional beauty combined with non-construction appears as perfect recreation a body in its original and natural form. The clothing takes a form that does not have any structural design and has simplified cutting and sewing. It uses pins and strings to fix up the form of clothing which is flexible and naturally draped. The sensual beauty combined with natural body is found in natural silhouette dress alluding naked body in connection with Rousseau' naturalism in neoclassic period. Throughout the twentieth century, the desire for Grecian style was conveyed by a single detail or through an array of allusive effects.

동안(童顔) 열풍의 사회문화적 배경과 골상학적 특징 (A Study on the Sociocultural Backgrounds of the 'Baby Face Fad' and Phrenological Characteristics)

  • 김남희;오인영
    • 한국의류학회지
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    • 제33권10호
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    • pp.1530-1540
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    • 2009
  • Life expectancy has increased and people are more concerned with keeping their 'youth'. Appearance is a competitive edge and people are caught up in a baby face fad that has expanded into a culture and beauty trend. This study examined the definitions and phrenological characteristics of a baby face and the causes of the baby face fad in a review of the baby face as a "sociocultural and beauty cultural code" based on literature, journals, previous papers, and Internet materials. Anatomically speaking, a "baby face" refers to a face that keeps the features of a child's face without aging signs. The baby face fad gained momentum due to the influences of the digital culture, the encouragement of the mass media, changes to the social structure, dietary improvements, new living styles, and an evolving aesthetic sense. The results reveal the sociocultural backgrounds behind the "baby face fad" settling down as a part of culture in addition to the phrenological characteristics of a baby face. It is also estimated that the baby face fad could affect the beauty culture and trends as a social phenomena.

건수록(建殊錄)에 수록된 길익동동(吉益東洞)의 의안에 대한 연구 (Study on the Medical Records/Clinical Case Reports of "Kenjuroku")

  • 김재은;최달영
    • 동의생리병리학회지
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    • 제23권2호
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    • pp.269-277
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    • 2009
  • "Kenjurok" is a set of medical records of Todo Yoshimasu, a Japanese docotr in the eighteenth century, who suggested that all diseases have originated from a poison, which is his own pathological term describing abnormal states of the body, The 54 records in "Kenjurok" were analyzed in statistical respects, including gender ratio, demographic distribution of patients, types of diseases, and herbal prescriptions used. Among 54 cases, male patients outnumbered female, as much as four times. The patients were quite evenly distributed according to ages. In 23 cases out of 54, abdomen palpation data were mentioned, Majority of the prescriptions used were originated from Sanghanron(傷寒論:Treaties on Febrile Diseases)/Geumgeyoryak(金匱要略: Synopsis of Golden Chamber). In frequency of use of prescriptions, however, showed somewhat different result, that is although Sanghan/Geumge prescriptions were used most often, esoteric prescriptions handed down in his family also composed significant part. The speculations derived from these statistical results are: Although Todo favored abdommen palpation to locate the poison and to decide a prescription, the proportion of abdomen palpation was not as high as expectation, He did use prescriptions not only in Sanghan/Geumge, but also other diverse prescriptions, rather often than not, which are regarded unique Japanese traditional prescriptions including poisonous minerals such as mercury and arsenic.

가솔린과 바이오 에탄올 혼합 연료의 엔진 및 차량 모드 주행시의 입자상 물질 배출 특성 (Particle emission characteristics of gasoline and bio ethanol blend in the engine and vehicle mode test)

  • 고아현;이형민;최관희;박심수;이영재
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회B
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    • pp.3102-3107
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    • 2008
  • This paper was focused on the particulate matter (PM) on the gasoline and bio ethanol. Bio ethanol as a clean fuel is considered one of the alternative fuels that decreased the PM emission from the vehicle. Particle formation in SI engine was depended on the fuel and engine operating condition. In this paper, Particle number concentration behaviors were analyzed by DMS500 (Differential Mobility Spectrometer) and CPC (Condensation Particle Counter) instrument which was recommended by PMP (Particle Measurement Programme). Particle emissions were measured with various engine operating variables such as air excess ratio ($\lambda$), spark timing and intake valve opening (IVO) at part load condition. In vehicle test, the number of particulate matter was analyzed with golden particle measurement system, which was consist of CVS (Constant Volume Sampler), particle number counter and particle number diluter.

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