• Title/Summary/Keyword: WF

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Heat transfer characteristics of an internal cooling channel with pin-fins and ribbed endwalls in gas turbine blade

  • Vu T.A. Co;Hung C. Hoang;Duy C.K. Do;Son H. Truong;Diem G. Pham;Nhung T.T. Le;Truong C. Dinh;Linh T. Nha
    • Advances in aircraft and spacecraft science
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    • v.11 no.2
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    • pp.153-175
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    • 2024
  • In jet engines, turbine blade cooling has an extremely important role. The pin-fin array, which is situated close to the trailing edge of the blade, aids in internal cooling of the gas turbine blades and preserves the structural integrity of the blade. Previous studies often focused on pin-fin configurations, but the current research focuses on improving the geometry at the endwalls to reduce wake vortices behind the pin-fins and enhance heat transfer at the endwalls location. Using the k-ω turbulence model, a numerical study was conducted on a ribbed shape situated on the walls between pin-fin arrays, spanning a Reynolds number range of 7400 to 36000, in order to determine the heat transport characteristics. The heat transfer efficiency coefficient and Nusselt number increase dramatically with the revised wall configuration, according to the numerical data. The channel's heat transfer efficiency is increased by enlarging the heat transfer areas near the pin-fins and by the interaction of the flow with the endwalls. The addition of ribs causes the Nusselt number of the new model to climb from 78% to 96% at the previously given Reynolds numbers, and the heat transfer efficiency index to rise from 60% to 73%. The height (Hr), position (Lr), forward width (Wf), and backward width (Wb) of the ribs are among the geometric elements that were looked at in order to determine how they affected the performance of heat transmission. In comparison to the reference design, the parametric study results demonstrate that the best forward width (Wf/R=18.75%) and backward width (Wb/R=31.25%) increase the heat transfer efficiency index by 0.4% and 1.3%, respectively.

Effects of Wilting and Additives on the Fermentation Chrateristics , Quality and Aerobic Stability of Rye Silage (예건 및 첨가제가 호밀사일리지의 발효특성과 사료가치 및 호기적 안정성에 미치는 영향)

  • 이광녕;김동암
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.17 no.2
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    • pp.187-198
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    • 1997
  • This experiment was conducted to evaluate effects of wilting and additives on fermetation characteristics, quality and aerobic stability of silage of rye(Seca1e cereale L.) harvested at the early heading stage. Harvested rye was wilted or mixed with beet pulp and then treated with formic acid or lactic acid bacteria(LAB) inoculant. Treatments were consisted of direct cut(DC), wilted(WT), beet pulp added(BP), direct cut and formate applied(DF), wilted and formate applied(WF), beet pulp and formate applied(BF), direct cut and LAB inoculated(DL), beet pulp added and LAB inoculated(BL), and wilted and LAB inoculated(WL) silages. Afler 70 days of ensiling period, the silages were opened and exposed to air for 7 days, and the silages of opening day(0 day) were compared with the silages exposed to air for 7 days(7 day). 1. LAB inoculated rye silages(DL, WL, BL) lowered pH values effectively eom the third day of ensiling and showed most stable pattern of pH changes during the initial fermentation process. Direct cut and formate applied(DF), beet pulp and formate applied(BF) and beet pulp added(BP) silages were also effective in lowering pH from the seventh day thai direct cut treatment(DC). 2. pH was low below 3.7 in all treatments of 0 day. After 7-day period of aerobic exposure, DL and WL showed considerable increases in pH from 3.5 and 3.4 to 8.3 and 6.4, respectively. 3. Direct cut rye silages(DF, DC, DL) and beet pulp and formate treatment(BF) produced effluent of 121.2, 85.9, 80.3 and 34.2 mlkg, respectively and these were greater than others(P<0.01). Beet pulp retained 1.61 I/kg of effluent at the application rate of 50 kg/t in comparing BP with DC, and formate application increased the amount of effluent in comparing DF and BF with DC and BP, respectively(P<0.01). 4. Beet pulp and LAB treatment(B1) was highest in content of lactate as 3.1% and formate treated silages(DF, WF, BF) showed lower content of lactate and total acid than others. LAB inoculated(D1, WL, BL) and wilted (WT) silages were graded to be good quality as a second group by the Flieg's score. Formate applied silages (DF, WF, BF) were graded as a foum group lower than DC by one. 5. Residual content of WSC of rye silage was higher in BP, BF, DL and BL than direct cut treatment(M3) (P< 0.01). Formate application had a tendency to increase the content of residual content of WSC. 6. For the ratio of NH3-N to Total N, wilted and LAB inoculated(W1) and direct cut and LAB inoculated(D1) silages were lowest on 0 day as 8.9 and 9.3% respectively. But after 7-day period of aerobic exposure, WL and DL showed largest increase of the ratio of $NH_3-N$ to Total N from 0 day(P<0.01). 7. On 0 day wilted(WT), beet pulp and formate treatment(BF), and beet pulp and LAB treatment(B1) were lower than direct cut treatment(DC) for NDF and ADF concentrations consistently. Formate applied silages (DF, WF, BF) made little change in ADF and NDF concentrations during 7 day period of aerobic exposure. DL and WL showed a large increase in ADF and NDF concentrations under aerobic condition(P<0.01). 8. IVDMD values of wilted(WT), beet pulp added(BP), wilted and LAB inoculated(W1) and beet pulp added and LAB inoculated(B1) silages were higher than direct-cut treatmentPC) as 84.7, 84.7, 84.4 and 83.0%, respectively on 0 day. But during 7-day period of aerobic exposure, a great decreae in IVDMD of WL was showed(P<0.01). The experimental results indicate that wilted silage(WT) could be recommended as the most effective treatment for reducing efluent and increasing quality and feed value of rye silage without deteriorating aerobic stability more than direct cut treatment(DC). Additionally, under unfavorable weather condition beet pulp added and LAB inoculated treatment(T3L) might be the possible alternative for successful ensiling of forage rye.

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이동 에이전트 기반 워크플로우 시스템의 설계 및 구현

  • 박원주;김병만;김현수
    • Journal of Software Engineering Society
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    • v.13 no.3
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    • pp.18-30
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    • 2000
  • 기존 워크플로우 시스템은 비즈니스 프로세스 내의 정보와 제어의 흐름 수행에 있어서 중앙 집중적인 워크플로우 엔진이 전체 실행의 모든 부분을 담당하고 있다. 이러한 워크플로우 시스템이 갖는 성능, 확장성 등 구조적 제약의 단점을 극복하기 위하여 워크플로우 엔진의 분산, 이동 에이전트의 적용, 웹 기반 등 다양한 연구가 진행되고 있다. 본 논문에서는 단위 업무 스케쥴링 기능과 관련된 정보를 분산된 형태로 참가자에게 일임하여 워크플로우 엔진 부하를 줄이고, 프로세스 인스턴스 단위의 이동 에이전트를 적용하여 비동기적 특성을 이용한 성능 및 확장성의 향상을 제공하는 워크플로우 시스템의 설계 및 구현을 소개한다. 또한 제안한 시스템을 위하여 각 참가자별 스케쥴링 정보를 WfMC의 프로세스 정의 표준 언어인 WPDL로부터 추출하여 프로세스 테이블로 구성하는 방법을 제안한다.

Analysis of Post-tensioned Bridge by Specially Orthotropic Laminate Theory (II) - Steel Plate Girder Bridge (특별직교이방성 이론에 의한 포스트 텐션된 교량의 해석(II) - 강 판형교 -)

  • 김덕현;원치문;이정호
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.141-146
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    • 2001
  • A post-tensioned steel plate girder bridge with cross-beams is analyzed by specially orthotropic laminate theory. The cross-sections of both girders and cross-beams are WF types. The result is compared with that of the beam theory. This bridge with simple support is under uniformly distributed vertical load, and axial loads and moment due to post-tension. In this paper, finite difference method for numerical analysis of simple supported bridge is developed. Relatively exact solution is obtained even with small number of meshes. Theory and analysis method of specially orthotropic laminate plates used in this paper can be used in design of new bridges, and maintenance and repair of old bridges.

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Variations in Childcare Style and Work-Family Conflict Related to Extended Working Hours: Focusing on Employed Mothers of Preschoolers or Elementary-School Children (연장근로에 따른 아동돌봄 형태와 일 가족 갈등: 초등학생 이하 자녀를 둔 취업모를 중심으로)

  • Sung, Hea-Young
    • Journal of the Korean Home Economics Association
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    • v.48 no.9
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    • pp.79-87
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    • 2010
  • The purpose of this study was to investigate whether employed mothers' extended working hours have effects on childcare style and work-family conflicts. The data came from the 2007 Korean Longitudinal Survey of Women and Family(KLoWF) of the Korean Women's Development Institute. 475 females with preschoolers or elementary-school children were used in this study. The major findings can be summarized as follows: (1) Weekly average working hours varied by education, salary, and the presence of preschoolers. (2) The time of childcare was significantly shorter in mothers who work more than 50 hours/week (3) Mothers who worked more than 50 hours/week felt significantly high work-family conflict. These analyses pointed to the importance of obeying the law related to working hours as the most important thing to sustain work-family balance. Institutional foundations should be enabled to keep legal working hours.

Properties of cotton fabric treated with $TiO_2$/PEG ($TiO_2$/PEG처리 면직물의 특성)

  • 김정진;장정대
    • Textile Coloration and Finishing
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    • v.14 no.3
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    • pp.53-58
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    • 2002
  • Cotton fabric was treated with TiO$_2$-PEG600 mixed solution by pad-dry-cure and wet-fixation process to improve the performance properties as well as antibiosis effect and its laundering durability. In this paper, the effects of concentration of $TiO_2/PEG$ and fixation process were investigated on laundering durability and properties of cotton fabric treated with glyoxal. As the concentration of $TiO_2/PEG$ increased fixation, W.I., K/S of treated cotton fabric increased. Application of wet-fixation method provided a further improvement in fixation, laundering durability of treated cotton fabric.

Properties and UV-cut effects of cotton fabric treated with $TiO_2$/PEG ($TiO_2$/PEG처리 면직물의 물성과 자외선 차단성능)

  • 김정진;장정대
    • Textile Coloration and Finishing
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    • v.14 no.4
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    • pp.223-228
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    • 2002
  • Cotton fabric was treated with $TiO_2$-PEG600 dispersion colloid by pad-dry-cure and wet-fixation process to improve the performance properties as well as UV-cut effect. As the concentration of $TiO_2$/PEG increased tensile strength, crease resistance, stiffness of treated cotton fabric increased. Application of wet-fixation method provided a further improvement in tensile strength, crease resistance, stiffness of treated cotton fabric. Cotton fabric treated with $TiO_2$/PEG was more efficient in UV-cut property than untreated cotton.

Deposition of Tungsten Thin Films on Silicon Substrate by Microwave Plasma Enhanced Chemical Vapor Deposition (PECVD) and Low Pressure Chemical Vapor Deposition (LPCVD) Techniques (마이크로파 플라즈마 화학기상증착법(PECVD)과 저압 화학기상증착법(LPCVD)을 이 용한 실리콘 기판 위에서의 텅스텐 박막증착)

  • 김성훈;송세안;김성근
    • Journal of the Korean Vacuum Society
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    • v.1 no.2
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    • pp.277-285
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    • 1992
  • 플라즈마 화학기상증착법과 저압 화학기상증착법을 사용하여 실리콘 기판 위에 텅 스텐 박막을 증착하였다. 반응기체로 WF6를 사용하였으며 환원기체로는 SiH4를 사용하였다. 플라즈마 증착법에 의한 텅스텐 박막의 성장은 환원기체의 유무에 상관없이 주로 기상 반응 에 의한 텅스텐 덩어리들의 증착에 의하여 이루어졌으며 비교적 균일도가 낮은 박막표면을 이루었다. 저압 화학증착법의 경우 환원기체를 사용하지 않았을 때에는 실리콘 기판에 의한 제한된 환원반응에 의해 텅스텐이 증착되었으나, 환원기체를 사용했을 때에는 초기의 실리 콘 기판에 의한 환원반응과 이어 일어나는 SiH4 기체와의 불균일계 환원반응의 두 단계반응 에 의하여 텅스텐 박막 증착이 이루어졌다. 저압 화학증착법의 경우 텅스텐 박막의 특성은 플라즈마 증착법에서 보다 우수하였으며 박막 성장은 island by island 양식을 따르는 것으 로 추정되었다. 박막은 $\alpha$-W의 체심입방 구조로 이루어졌으며 박막이 성장함에 따라 단결정 구조가 증가하였다.

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Design of Mobile Agent based-Workflow System using Distributed Scheduling (분산 스케쥴링을 이용한 이동 에이전트 기반 워크플로우 시스템의 설계)

  • 박원주;김병만;김현수
    • Proceedings of the Korean Information Science Society Conference
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    • 2000.10c
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    • pp.552-554
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    • 2000
  • 기존 워크플로우 시스템은 비즈니스 프로세스 내의 정보와 제어의 흐름 수행에 있어서 중앙 집중적인 워크플로우 엔진이 전체 실행의 모든 부분을 담당하고 있다. 이러한 워크플로우 시스템이 갖는 성능, 확장성 등 구조적 제약의 단점을 극복하기 위하여 워크플로우 엔진의 분산, 이동 에이전트의 적용, 웹 기반 등 다양한 연구가 진행되고 있다. 본 논문에서는 단위 업무 스케쥴링 기능과 관련된 정보를 분산된 형태로 참가자에게 일임하여 워크플로우 엔진 부하를 줄이고, 프로세스 인스턴스 단위의 이동 에이전트를 적용하여 비동기적 특성을 이용한 성능 및 확장성의 향상을 제공하는 워크플로우 시스템의 설계를 제안한다. 또한 제안한 시스템을 위하여 각 참가자별 스케쥴링 정보를 WfMC의 프로세스 정의 표준 언어인 WPDL로부터 추출하는 방법을 제안한다.

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Practical Workflow Interoperation Model Using Remote Process Proxy (원격 프로세스 프록시를 이용한 실용적 워크플로우 상호운용 모델)

  • 권헌걸;이성독;한동수;서범수
    • Proceedings of the Korean Information Science Society Conference
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    • 2003.10c
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    • pp.613-615
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    • 2003
  • 최근, 인터넷이라는 개방형 네트워크가 보편화 되면서 인터넷을 매게로 한 전자적인 거래의 형태가 기업 대 소비자(B2C) 거래에서부터 기업 대 기업(B2B) 거래 그리고 기업 대 정부(B2G) 거래까지 다양하게 발전하고 있다. 본 논문에서는 WfMC에서 제시하는 표준을 준수하면서 동시에 워크플로우 시스템의 사용자인 프로세스 설계자 그리고 워크플로우 프로세스 참여자 모두에게 쉬운 인터페이스를 제공할 수 있는 워크플로우 시스템의 아키텍처 및 모델을 제시한다. 본 모델은 P2P기반의 현실적인 대안을 위해서 설계되었으며, 기존 연구에서 가볍게 취급되어 왔던 워크플로우 시스템 사용자를 위한 인터페이스를 고려하여 설계되었다.

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