• 제목/요약/키워드: form drag

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1990년대 하위문화 스타일에 관한 연구 (A Study on the Subcultural Style in the 1990s)

  • 임은혁;김민자
    • 복식
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    • 제53권3호
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    • pp.13-31
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    • 2003
  • The purpose of this study is to analyze the formative style and aesthetic value of contemporary subcultural style with the understanding of characteristics of subcultural style in the sociocultural context. As for the research methodology, literary survey has been performed to study the concept and the history of subcultural styles from 1940s to 1980s. In addition, demonstrative studies on aesthetic images have been carried out through the analysis of pictures and photographs in order to categorize the subcultural styles since 1990s. In this study, subcultural styles since 1990s have been illustrated through the socio-cultural grounds. which are diversity of street culture, diffusion of moss culture or bubble-up phenomenon, pursuit of anti-social ideology among intellectual heads, club Cultures in the form of kitsch and pastiche and communal thinking as collective harmony. With the socio-cultural context examined above, subcultural styles in the contemporary fashion are categorized and deduced following aesthetic values ; Drag and Club style as the tendency of surrealists or artificial hedonists, Urban military style and Cyberpunks as pursuit of Bionic being, Sports casual style based upon, the pursuit of comfort and freedom, Vintage style and Retro dressing represented by the spirit of DIY (no It Yourself), Ecology style of New conservatives, and Mysticism style as the fusion of technology and shamanism (Technoshamanism).

표면조도가 있는 난류경계층의 직접수치모사 (Direct numerical simulations of the turbulent boundary layers over the rough walls)

  • 이재화;성형진
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2011년 춘계학술대회논문집
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    • pp.379-381
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    • 2011
  • Direct numerical simulations (DNSs) of spatially developing turbulent boundary layers (TBLs) over two-dimensional (2-D) and rod and three-dimensional (3-D) cube rough walls were performed to investigate the effects of streamwise spacing on the properties of the TBL The 2-D and 3-D roughness were periodically arranged in the downstream direction with pitches of px/k=2, 3, 4, 6, 8 and 10 and for the cube, the spanwise spacing is fixed to pz/k=2 with staggered array, where px and pz are the streamwise and spanwise spacings of the roughness and k is the roughness height. Inspection of the Reynolds stresses showed that except for px/k=2 and 3 over the 2-D rough walls, the effects of the surface roughness extend to the outer layer over the 2-D and 3-D rough walls and the magnitude of the Reynolds shear stress in the outer layer is increased with proportion to px/k. However, such results are contrary to the trends of form drag, roughness junction and roughness length against px/k, which showed the maximum values at px/k=8 and 4 over the 2-D and 3-D rough walls respectively.

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제트 블로잉에 의한 에어포일의 실속후 특성 향상 (Enhancement of Airfoil Post-Stall Characteristics via a Jet Blowing)

  • 이기영;정형석;조동현;손명환
    • 한국군사과학기술학회지
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    • 제10권2호
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    • pp.188-197
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    • 2007
  • Active flow control, in the form of steady and unsteady momentum injection via jet blowing was studied. A jet was obtained by pressing a plenum inside the airfoil and ejecting flow out of a thin slot. The normal and drag forces were measured with leading edge or trailing edge blowing Jet and compared with the results obtained with no blowing. The blowing jet has been shown to improve the aerodynamic performance of the airfoil. The steady jet proved more effective than pulsating jet in these experimental conditions. Furthermore for the case of leading edge steady blowing jet, the alleviation of non-linearity in the normal force curve slope can be seen at higher angles of attack. No effective trailing edge jet was observed in this highly separated flow. This shows that the stall control is highly depends on the characteristics of the boundary layer near the jet slot.

Mesh size refining for a simulation of flow around a generic train model

  • Ishak, Izuan Amin;Alia, Mohamed Sukri Mat;Salim, Sheikh Ahmad Zaki Shaikh
    • Wind and Structures
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    • 제24권3호
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    • pp.223-247
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    • 2017
  • By using numerical simulation, vast and detailed information and observation of the physics of flow over a train model can be obtained. However, the accuracy of the numerical results is questionable as it is affected by grid convergence error. This paper describes a systematic method of computational grid refinement for the Unsteady Reynolds Navier-Stokes (URANS) of flow around a generic model of trains using the OpenFOAM software. The sensitivity of the computed flow field on different mesh resolutions is investigated in this paper. This involves solutions on three different grid refinements, namely fine, medium, and coarse grids to investigate the effect of grid dependency. The level of grid independence is evaluated using a form of Richardson extrapolation and Grid Convergence Index (GCI). This is done by comparing the GCI results of various parameters between different levels of mesh resolutions. In this study, monotonic convergence criteria were achieved, indicating that the grid convergence error was progressively reduced. The fine grid resolution's GCI value was less than 1%. The results from a simulation of the finest grid resolution, which includes pressure coefficient, drag coefficient and flow visualization, are presented and compared to previous available data.

글래머 스타일의 물신주의적 특성과 미적 가치 (Fetishist Characteristics and Aesthetic Values of Glamour Style)

  • 박주희;김민자
    • 복식
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    • 제57권4호
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    • pp.173-187
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    • 2007
  • The purpose of this study is to analyze the fetishist characteristics and the aesthetic values of glamour style based on the premise that fetishism is the theoretical root of glamour style expressed in fashion throughout history. The following results are from analysing fetishist characteristics of glamour style. First, luxury was analysed from an angle of commodity fetishism. Every culture develops images and stories that portray a world in which its ideals are realized: a paradise, a utopia, a golden age, etc. Consumer goods often serve as 'bridges to these ideals'. People thus can fantasize about owning the perfect life. Crucially, however, they must never get everything they picture. That is why luxuries often take on displaced meaning. Glamour gives the displaced meaning visual form, making it beautiful and real. Second, the attention on the glamour of luxury goods as a bridge to ideals is connected to the glamour icon who is simultaneously a consumer of these luxury goods and a producer of cultural goods. Glamour icons including the courtesan of the late 19th century, the actress of the 1930s' Hollywood golden age and today's celebrities appear to efface the traces of production and create fetishist images in culture. Through this artificial principle, the commodity-cum-glamour icon comes to life as a splendid image of spectacle. Third, masquerade and seduction were analysed from an angle of sexual fetishism. A magnificent image of masquerade as sexual fetishism is often equated with femininity, especially in Hollywood movies, because the artificial seduction of the feminine -namely glamour- can be effected by the absence or silence of being. That is to say, the aesthetic revelation of femininity coincides with the fleshing out of artificial signs. Masquerade and the seduction of the feminine are connected with glamour's artificial sensuality from this point. Fourth, since 1980's when homosexuality as sexual deviation resurfaced as a hot topic, sexual ambiguity and bisexual image have gained attention as perverse sexuality. Next came queer theory, which reduced gender itself to a matter of surface rather than depth. According to queer theory, gender itself can be revealed as a kind of drag act. Drag's imitative performance may reveal that womanliness is just about 'dragging up'. Queerness as a decadent play makes a connection with the wicked origins of glamour. From these characteristics, four aesthetic values were deduced: ostentatious luxury and mysterious idolatry by commodity fetishism, artificial sensuality and playful queerness by sexual fetishism.

18.5ft급 경기용 배스보트의 주요제원 선정에 관한 수치해석 연구 (A Numerical Study on the Selection of Main Specification of the 18.5ft Bass Fishing Boat)

  • 임준택;서광철;박근홍;김상원
    • 해양환경안전학회지
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    • 제24권7호
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    • pp.945-952
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    • 2018
  • 최근 국내에서 배스낚시는 하나의 해양레저 스포츠로서 자리매김하고 있다. 국내 배스 낚시협회는 총 4곳이 있으며 각 협회당 매년 10~15회의 토너먼트 대회를 개최하는 등 수요가 높은 편이다. 그러나 국내 대회에서 선호되는 17ft 이상 급의 배스보트의 경우 현재 100 % 수입에 의존하고 있는 실정이다. 본 연구에서는 해외실적선 자료를 바탕으로 통계분석을 통해 18.5ft급 경기용 배스보트의 초기선형 개발을 위한 주요제원을 도출하였다. 또한 활주선의 저항 및 활주성능에 큰 영향을 미치는 선저경사각 및 종방향 무게중심에 따른 CFD 수치해석을 수행하였다. 수치해석의 경우, 설계 속도인 $Fn=3.284 (Re=9.858{\times}10^7)$에 대해서 수행하였고, 선저 경사각은 $12{\sim}20^{\circ}$, 종방향 무게중심은 부력중심으로부터 선미방향으로 $0{\sim}8%L_{WL}$의 범위로 설정하였다. 수치해석 결과를 바탕으로, 1차적으로 저항성능과 침수용골 길이를 바탕으로 범위를 설정한 후, Savitsky의 Drag-Lift ratio의 상관그래프를 이용하여 최적 트림각에 근접한 선저경사각($14{\sim}16^{\circ}$), 종방향 무게중심위치($4{\sim}6%L_{WL}$)의 범위를 도출하였다.

시니어 남성용 드레스폼 개발을 위한 정장착의 실태조사 (The Actual Wearing Conditions of Formal Suits for Development of Senior Men's Dressform)

  • 도월희;최은희
    • 한국의류산업학회지
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    • 제20권3호
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    • pp.304-311
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    • 2018
  • This research used a questionnaire to provide basic data for the design of dressing form that enables the manufacture of senior menswear with an improved fit to match the dissatisfaction with the fit of male suits over the 50s. We used 132 questionnaires as analytical data. The results were: The item 'purchasing method of formal suits' showed that 95.5% purchased ready-to-wear jackets. The 'abdominal obesity type' and 'trunk waist type' had a high frequency of 'complaints about the size of the ready-to-wear jacket'. They choose their suits and wear them directly from the store. It is expected that senior males will complain about ready-to-wear formal suits due to the increase in girth item than normal type due to change of body shape since they consider size to also be important when purchasing suits. The most important part of the body when purchasing suits is the shoulder area, followed by the front width and back width of the fit. As for the degree of recognition of suit size, 38.1% said that they know the size and 'Suit size is hard to understand'. As a result of dissatisfaction with formal dressing, the items of 'Neck wide of get loose', 'Drag line of back neck', 'Not fit of front opening', 'Not fit of shoulder slope' and 'dissatisfaction'. Therefore, it is salient to establish suit fitting system and size system for senior men.

용융주조 현무암 튜브를 이용한 생활폐기물 이송관로의 보호벽에 관한 연구 (A Study on the Protecting Wall for Transferring Pipe of Waste Using Cast Basalt Tube)

  • 왕지석;김종도;윤희종
    • Journal of Advanced Marine Engineering and Technology
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    • 제34권6호
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    • pp.816-824
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    • 2010
  • 본 논문에서는 쓰레기 이송관로내의 물체에 작용하는 힘을 분석하고 그 물체의 운동방정식 확립하였다. 그 운동방정식은 1계 비선형 미분방정식이 되며 이것의 일반해를 이용하면 쓰레기 이송관로내 물체의 속도를 구할 수가 있다. 물체의 속도는 엘보우와 같은 쓰레기 이송관로의 곡선부에서 내벽의 충돌속도가 되므로 충돌시 물체의 운동에너지를 계산할 수 있고, 따라서 필요한 내벽의 충격강도를 알 수가 있다. 하나의 예로써 쓰레기 이송관로내 공기의 속도가 30m/sec일 때 물체의 속도를 계산하여 그래프로써 나타내었으며, 이것으로부터 물체가 내벽에 충돌할 때의 운동에너지를 계산할 수 있도록 하였다. 또한 용융주조 현무암 튜브를 철강파이프 내면에 보호벽으로 씌운 복합재료 파이프에 추를 자유낙하시켜 충격을 주는 방식으로 충격시험을 한 결과를 제시하였으며, 그 결과에 의하면 용융 주조 현무암 튜브는 쓰레기 이송관로의 내면 보호벽으로 충분한 충격강도를 가지는 것이 판명되었다.

저속 영역에서 루버휜이 장착된 평판관형 알루미늄 열교환기의 공기측 전열 성능에 대한 실험적 연구 (Air-side Performance of Louver-Finned Flat Aluminum Heat Exchangers at a Low Velocity Region)

  • 조진표;오왕규;김내현;윤백
    • 대한기계학회논문집B
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    • 제26권12호
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    • pp.1681-1691
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    • 2002
  • The heat transfer and pressure drop characteristics of heat exchangers with louver fins were experimentally investigated. The samples had small fin pitches (1.0 mm to 1.4 mm), and experiments were conducted up to a very low frontal air velocity (as low as 0.3 m/s). At a certain Reynolds number (critical Reynolds number), the flattening of the heat transfer coefficient curve was observed. The critical Reynolds number was insensitive to the louver angle, and decreased as the louver pitch to fin pitch ratio (L$_{p}$F$_{p}$) decreased. Existing correlations on the critical Reynolds number did not adequately predict the data. It is suggested that, for proper assessment of the heat transfer behavior, the louver pattern in addition to the flow characterization need to be considered. The heat transfer coefficient increased as the fin pitch decreased. At low Reynolds numbers, however, the trend was reversed. Possible explanation is provided considering the louver pattern between neighboring fins. Different from the heat transfer coefficient, the friction factor did not show the flattening characteristic. The reason may be attributed to the form drag by louvers, which offsets the decreased skin friction at a low Reynolds number. The friction factor increased as the fin pitch decreased and the louver angle increased. A new correlation predicted 92% of the heat transfer coefficient and 90% of the friction factor within $\pm$10%.10%.

소구경 탄자의 충돌속도 추정방법 제안 (A new method to estimate the striking velocity for small caliber projectiles)

  • 유상준;김제용
    • 한국산학기술학회논문지
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    • 제15권3호
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    • pp.1288-1293
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    • 2014
  • 본 논문은 MIL-STD-662F의 방호한계속도 산출을 위해 충돌속도를 추정하는 새로운 방법을 제안하였다. 기존 MIL-STD-662F의 방법은 충돌속도를 추정하기 위해 상대공기밀도, 항력계수, 형상인자, 탄도계수 등이 필요하여 기초연구가 필수적이라는 한계를 가지고 있다. 하지만 제안한 방법은 기초연구 없이도, 기기에서 측정된 속도와 측정기기와 타격점까지 거리만으로 충돌속도를 추정할 수 있다. 이를 검증하기 위해 M193탄과 M80탄을 사용하였고, 미국의 검증된 PRODAS의 데이터를 기반으로 MIL-STD-662F 방법의 충돌속도 추정값과 제안한 방법의 충돌속도 추정값을 비교하고 분석였다. 실험결과에서 제안한 방법이 일부 속도구간에서는 MIL-STD-662F의 방법보다 오차가 크지만 방호한계속도 산출은 가능하였고, 대부분의 속도구간에서는 MIL-STD-662F보다 오차가 작다는 것을 보였다.