• 제목/요약/키워드: Boundary working

검색결과 145건 처리시간 0.027초

정상상태인 박용 TP620 익형의 경계층 특성 연구 (A study on the boundary layer characteristics of TP620 hydrofoil in the steady state)

  • 서봉록;김시영
    • Journal of Advanced Marine Engineering and Technology
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    • 제10권4호
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    • pp.50-56
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    • 1986
  • This report deals with a study on the boundary layer characteristics of TP620 hydrofoil in the steady state by using two dimensional boundary layer theory. On the basis of complex velocity and laminar and turbulent boundary layer theory, the author attempts to know some tendency by evaluating the performance characteristic values of TP620 hydrofoil working in a uniform flow. In deriving characteristic values, he calculates numerically velocity, momentum thickness, skin friction coefficient, shape factor, and displacement thickness on the TP620 hydrofoil working at each attack angle in a uniform flow. Applying this present numerical calculation using Thwaites' and Head's method, the results of boundary layer on the hydrofoil are shown to be influenced by surface velocity and attack angle.

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A Study on the Factors affecting on Codependency. -Focusing on Double ABCX Model-

  • Ju, Sunyoung;Yang, Seongkwan;Park, Hwieseo
    • 한국컴퓨터정보학회논문지
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    • 제22권11호
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    • pp.117-124
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    • 2017
  • The purpose of this study was to examine the factors influencing on Codependency of college students from Double ABCX model. This study examined the mediating relationship between boundary ambiguity, internal working model and psychological maladjustment, and then examined the moderating effects of Self-esteem, Social support and World view orientation. This study also examined the relationships of codependency with gender, enonomic level in college students. The results of the study are as follows. First, this study showed that codependency was related to economic level of college students. But it has not significant relationship with gender. Second, the moderating effects of Self-esteem, Social support and World view orientation was not significant. Third, mediating effects of Codependency on Boundary ambiguity, Internal working model and Psychological maladjustment were significant. This study suggested some theoretical and policy implications basing on this analytical results.

A Laboratory Study of Formation of 'The Warm Core' in the East Sea of Korea

  • NA Jung Yul;KIM Bong Ho
    • 한국수산과학회지
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    • 제22권6호
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    • pp.415-423
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    • 1990
  • In a laboratory model the response of the boundary layer flow over topography is studied in a rotating sliced cylinder by employing the source-sink analogy with Ekman layer dynamics. The boundary layer flow is produced by two different fluid. In the first experiment homogeneous fluid is used both for the source and the working fluid of the container. In the second experiment a denser fluid is used for the source with the same working fluid. For the homogeneous western boundary layer flow both the northward and the southward flow were affected by the topography(ridge) to produce a cyclonic motion near the ridge. When woughward moving heavy boundary flow of slower speed and the northward moving faster flow were present at the same time, the splitting of southward flow and the separating of the northward flow were observed with a cyclonic motion at the ridge. The most important factor that influence production of the cyclonic motion has been turned out to be the presence of the topography in the western boundary layer. In particular the role of the southward moving heavy flow over the interior flow pattern was found to be very significant.

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고하중과 고속 미끄럼 베어링 시스템의 경계윤활에 대한 연구 (Study on Boundary Lubrication in the Sliding Bearing System under High Load and Speed)

  • 장시열
    • Tribology and Lubricants
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    • 제15권3호
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    • pp.248-256
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    • 1999
  • Many tribological components in automobile engine undergo high load and sliding speed with thin film thickness. The lubrication characteristics of the components are regarded as ether hydrodynamic lubrication or boundary lubrication, whereas in a working cycle they actually have both characteristics. Many modem engine lubricants have various additives for better performance which make boundary film formation even under hydrodynamic lubrication regime. Conventional Reynolds equation with the viewpoints of continuum mechanics concerns only bulk viscosity of lubricant, which means that its simulation does not give insights on boundary lubrication characteristics. However, many additives of modern engine lubricant provide mixed modes of boundary lubrication characteristics and hydrodynamic lubrication. Especially, high molecular weight polymeric viscosity index improvers form boundary film on the solid surface and cause non-Newtonian fluid effect of shear thinning. This study has performed the investigation about journal bearing system with the mixed concepts of boundary lubrication and hydrodynamic lubrication which happen concurrently in many engine components under the condition of viscosity index improver added.

병원종사자의 직무스트레스가 조직몰입과 고객지향영역초월행동에 미치는 구조적 영향관계 분석 (A Study on the Structural Impact of Job Stress on the Organizational Commitment and Customer Oriented Boundary Spanning Behavior of Hospital Employees)

  • 박혜영
    • 디지털융복합연구
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    • 제11권11호
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    • pp.603-611
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    • 2013
  • 본 연구는 병원종사자를 대상으로 직무스트레스, 조직몰입, 고객지향영역초월행동에 미치는 구조적 관계를 알아보고자 하였다. 서울 및 경기에 근무하는 병원종사자를 대상으로 2013년 4월1일부터 4월30일까지 배포하여 최종적으로 147부의 설문을 SPSS 18.0와 AMOS 18.0프로그램을 이용하여 실증 분석하는데 사용하였다. 분석결과, 가설 1의 병원종사자들의 직무스트레스가 조직몰입에 부(-)적인 영향을 미치는 것으로 나타났다. 가설 2의 병원종사자들의 조직몰입은 고객지향영역초월행동에 정(+)적인 영향을 미치는 것으로 나타났다. 가설 3의 병원종사자들의 직무스트레스가 고객지향영역초월행동에 부(-)적인 영향을 주는 것으로 나타났다. 따라서 병원종사자들의 조직몰입은 직무스트레스와 고객지향영역초월행동 간의 관계에서 부분적 매개역할을 하는 것을 알 수 있었다. 병원이 경쟁력을 가지기 위해서는 서비스품질을 향상시켜야 한다. 따라서 가장 중추적인 역할을 하는 병원종사자들의 스트레스를 줄이는 방안을 마련함으로써 조직몰입을 증가시킬 수 있으며 고객과의 접점에 있는 종사자들의 고객지향초월영역행동을 높일 수 있을 것이라는 점을 시사한다.

[ $SRV^{(R)}$ ]-Testing of the Tribosystem Piston Ring and Cylinder Liner Outside the Engine

  • Woydt Mathias;Ebrecht Johannes
    • KSTLE International Journal
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    • 제6권2호
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    • pp.58-64
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    • 2005
  • An OEM driven working group started in January 2004 to elaborate the philosophies, concepts and test procedures for testing piston ring and cylinder liner materials as well as engine oils outside the engine using the $SRV^{(R)}$ test equipment. The different $SRV^{(R)}$ test philosophies in use by OEMs are compiled. The working group focuses on a.) ASTM sequence VIB (Fuel economy by aging oils), b.) friction and wear in the top dead region under mixed/boundary lubrication, c.) extreme pressure load under mixed/boundary lubrication and d.) hydrodynamic friction. Tribological test result and precision data are presented.

Effects of decay heat and cooling condition on the reactor pool natural circulation under RVACS operation in a water 2-D slab model

  • Min Ho Lee ;Dong Wook Jerng ;In Cheol Bang
    • Nuclear Engineering and Technology
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    • 제55권5호
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    • pp.1821-1829
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    • 2023
  • The temperature distribution of the reactor pool under natural circulation induced by the RVACS operation was experimentally studied. According to the Bo' based similarity law, which could reproduce the temperature distribution of the working fluid under natural circulation, SINCRO-2D facility was designed based on the PGSFR. It was reduced to 1 : 25 in length scale, having water as a simulant of the sodium, which is the original working fluid. In general, temperature was stratified, however, effect of the natural circulation flow could be observed by the entrainment of the stratified temperature. Relative cooling contribution of the upper plenum (narrow gap) and lower plenum was approximately 0.2 and 0.8, respectively. In the range of decay heat from 0.2% to 1.0%, only the magnitude of the temperature was changed, while the normalized temperature maintained. Boundary temperature distribution change made a global temperature offset of the pool, without a significant local change. Therefore, the decay heat and cooling boundary condition had no significant effect on temperature distribution characteristics of the pool within the given range of the decay heat and boundary temperature distribution.

스테인레스강 SS420의 입계예민화에 의한 피트 부식 (Pit Corrosion of SS420 Stainless Steel by Grain Boundary Sensitization)

  • 최병학;이범규;장현수;박찬성;김진표;박남규;김청인;김보미
    • 한국재료학회지
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    • 제27권8호
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    • pp.431-437
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    • 2017
  • This study investigated the surface pit corrosion of SS420J2 stainless steel accompanied by intergranular crack. To reveal the causes of surface pits and cracks, OM, SEM, and TEM analyses of the microstructures of the utilized SS420J2 were performed, as was simulated heat treatment. The intergranular cracks were found to have been induced by a grain boundary carbide of $(Cr,Fe)_{23}C_6$, which was identified by SEM/EDS and TEM diffraction analyses. The mechanism of grain boundary sensitization occurred at the position of the carbide, followed by its occurrence at the Cr depleted zone. The grain boundary carbide of $(Cr,Fe)_{23}C_6$ type precipitated during air cooling condition after a $1038^{\circ}C$ solid solution treatment. The carbide precipitate formation also accelerated at the band structure formed by cold working. Therefore, using manufacturing processes of cooling and cold working, it is difficult to protect SS420J2 stainless steel against surface pit corrosion. Several counter plans to fight pit corrosion by sensitization were suggested, involving alloying and manufacturing processes.

터빈 캐스케이드 입구경계층 두께와 경계층 펜스 효과에 대한 실험적 연구 (Experimental Study on Effects of Inlet Boundary Layer Thickness and Boundary Layer Fence in a Turbine Cascade)

  • 전용민;정진택
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 춘계학술대회논문집B
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    • pp.853-858
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    • 2000
  • The working fluid from the combustor to the turbine stage of a gas turbine makes various boundary layer thickness. Since the inlet boundary layer thickness is one of the important factors that affect the turbine efficiency. It is necessary to investigate secondary flow and loss with various boundary layer thickness conditions. In the present study, the effect of various inlet boundary layer thickness on secondary flow and loss and the proper height of the boundary layer fences for various boundary layer thickness were investigated. Measurements of secondary flow velocity and total pressure loss within and downstream of the passage were taken under 5 boundary layer thickness conditions, 16, 36, 52, 69, 110mm. It was found that total pressure loss and secondary flow areas were increased with increase of thickness but they were maintained almost at the same position. At the fellowing research about the boundary layer fences, 1/6, 1/3, 1/2 of each inlet boundary layer thickness and 12mm were used as the fence heights. As a result, it was observed that the proper height of the fences was generally constant since the passage vortex remained almost at the same position. Therefore once the geometry of a cascade is decided, the location of the Passage vortex and the proper fence height are appeared to be determined at the same time. When the inlet boundary layer thickness is relatively small, the loss caused by the proper fence becomes bigger than endwall loss so that it dominates secondary loss. In these cases the proper fence hight is decided not by the cascade geometry but by the inlet boundary layer thickness as previous investigations.

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간호사의 일-가정 경계선 관리 (Nurses' Work-family Boundary Management)

  • 김미영
    • 간호행정학회지
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    • 제19권1호
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    • pp.17-27
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    • 2013
  • Purpose: This study was done to explore how nurses manage the boundary for work-family balance. Methods: Data were collected through in-depth interviews from February 1 to May 28, 2012. Participants were 13 married nurses with children. The constant comparative method was adapted for data analysis. Results: In this study, nurses' work-family boundary management had characteristics of integration, maintenance and control, but it was adjusted and modified over time as the order of priorities was rearranged according to changes in internal cognition and family support. Nurses strategically persuaded their families to understand their work and share housework in an effort to integrate work and family, while controlling them by managing working hours and time for themselves. Conclusion: The results of the study indicate that nurses' work has an impact on family life due to heavy workload and insufficient time, however the work-family balance can be successfully maintained with the effective separation of the two areas.