• 설비공학논문집
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• 제4권4호
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• pp.289-298
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• 1992

Fouling is "a major unsolved" area in heat transfer research. Currently, fouling researches are performed in every directions-fundamental aspects, modeling and cumulating experimental data. In this study, an attempt was made to extend the knowledge in enhanced tube fouling. The Kern-Seaton fouling model which was originally proposed for smooth tube fouling was extended to repeated rib tubes. Key parameters-mass transfer coefficient and wall shear stress-were modeled for repeated rib tubes. Some critical points related with the enhanced tube fouling-uncertainties in the mass transfer rate, wall shear stress modeling, deformation of roughness shape during fouling-were discussed, and some quantitative evaluations were made.

• Journal of Advanced Marine Engineering and Technology
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• 제20권1호
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• pp.1-12
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• 1996

The fully developed tubulent momentum and heat transfer induced by the square- ribbed roughness elements on both the inner and outer wall surfaces in the concentric annuli are studied analytically based on a modified turbulence model. Heat transfer coefficients for two conditions, i.e, a) inner wall heated as constant heat flux and outer wall insulated b) inner wall insulated and outer wall heated as constant heat flux, are investigated. The analytical results of the fluid flow are verified by experiment. The experiment is done with a pitot tube and a X-type hot wire anemometer to measure the time mean velocity profiles, zero shear stress positions, maximum velocity profiles and friction factors, and etc. The resulting momentum and heat transfer are discussed in terms of various parameters, such as the radius ratio, the relative roughness, the roughness density, Nusselt number and Prandtl number.

• 한국자동차공학회논문집
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• 제4권5호
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• pp.26-36
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• 1996

The fully developed turbulent momentum and heat transfer induced by the square-ribbed roughness elements on both the inner and outer wall surfaces in concentric annuli are studied analytically based on a modified turbulence model. The analytical results of the fuid flow are verified by experiment. The experiment is done with a pitot tube and a X-type hot wire anemometer to measure the time mean velocity profiles, zero shear stress positions, maximum velocity positions and friction factors, and etc. shown in Fig.1. The resulting momentum and heat transfer are discussed in terms of various parameters, such as the radius ratio, the relative roughness, the roughness density, Reynolds number, Nusselt bumber and Prand시 number. The study demonstrates that certain artificial roughness elements may be used to enhance heat transfer rates with advantage from the overall efficiency point of view by investigating turbulent flows and heat transfer in Fig.1.

• 대한기계학회논문집
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• 제11권2호
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• pp.214-221
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• 1987

본 논문에서는 2차원충돌분류에서 사각리브(rib)를 갖는 요철형전열면에 대한 실험에 관한 것이며, 리브의 높이를 (ｅ=5nm) 일정하게 하고 리브의 피치(ｐ=25,35,50 nm) 변화, 노즐출구와 전열면간 거이(H/B=1~14) 및 노즐출구유속(ｕ$_{e}$=12.30~ 18.07m/s)의 변화에 따른 전열특성을 실험적으로 구명하고 평판전열면의 경우와 비교 검토한다. 또한 스모크와이어(smoke-wire)법으로 평판 및 리브판에서의 유체의 거동 을 가시화하여 전열기구의 정성적 특성을 검토하는데 목적이 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.545-550
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• 2000

Bond between reinforcing bars and the surrounding concrete is supposed to safely transfer load in the design process of reinforced concrete structures. Bar with high relative rib area will be studied further not only static load but also dynamic loading conditions to sustain better performance of bond for reinforced concrete structures under earthquake. To determine the bond behavior of high ribbed bars in beam and column joints under repeated loads, 31 pullout specimens were tested. Bond strength increases as relative rib area increases. Also the effect of relative rib area on bond is larger in cyclic loading than in monotonic loading.

• 반도체디스플레이기술학회지
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• 제6권3호
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• pp.7-11
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• 2007

The design and manufacture of injection-molded parts with desired properties is a costly process dominated by empiricism, Including the repeated modification of actual tooling. The objective of this study is to obtain the good design of injection-molded polymeric parts using axiomatic design approach.

• 한국구조물진단유지관리공학회 논문집
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• 제23권1호
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• pp.85-93
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• 2019

프리캐스트 바닥판 공법은 바닥판간 이음부가 존재하며, 이음부의 연결성능에 따라 전체 교량 구조물의 성능이 좌우되므로 이음부의 연결성능 확보가 중요한 요소이다. 특히, 교량바닥판은 차량하중과 같은 반복하중을 받는 구조물이므로 피로하중에 대한 이음부의 거동 및 성능평가가 이루어져야 한다. 본 연구에서는 비대칭 요철형 루프이음을 적용한 2거더 연속합성형 교량을 제작하여 정적 및 200만회 반복하중의 피로실험을 통해 프리캐스트 바닥판의 구조적 거동 및 균열양상을 검토하였다. 실험결과, 제안된 프리캐스트 바닥판 연결시스템은 균열 폭, 누수, 인장철근의 응력 등 충분한 피로성능 및 파괴강도를 확보하는 것으로 나타났으며, 프리캐스트 바닥판 이음부에 효과적으로 적용 가능할 것으로 판단된다.

• 대한설비공학회지:설비저널
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• 제17권4호
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• pp.350-356
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• 1988

The impinging air jet system is still being used in the various fields with its inherent merits, that is, the easiness in engineering application and high heat transfer coefficients at stagnation point. The purpose of this study is augmentation of heat transfer without additional power in the rectangular air jet which impinges vertically to the heating surface. As a method of passive heat transfer augmentation in a two-Dimensional impinging jet, the transverse-repeated surface roughness of square cross-section is used. This paper deals with the experimental study on the characteristics of heat transfer at the x-direction in between nozzle exit and heating surface of flat plate, and that of ribbed plate. And this study also investigates the effect of square rib widths. The integral average heat transfer coefficient of ribbed plate is about 2.2 times larger than that of flat plate.

• 한국음향학회지
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• 제33권3호
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• pp.191-199
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• 2014

파이프, 평판과 같이 단면의 형상이 길이 방향으로 일정한 도파관 구조물을 따라 전파되는 진동의 반사 및 투과 특성은 여러 공학 분야에서 응용되는 중요한 주제이다. 도파관에 조인트 또는 균열 등의 국부적 불연속이 있는 경우, 스펙트럴 요소(spectral element)와 유한 요소(finite elment)를 결합한 SE/FE 방법이 주로 사용되고 있다. 그러나 이 방법은 보 이론에 기반한 스펙트럴 요소가 사용되므로 저주파수 대역 해석에 국한되는 단점이 있다. 고주파수 대역 해석에는 스펙트럴 수퍼 요소(spectral super element)와 유한 요소를 결합한 SSE/FE 방법이 제안되었으나 유한요소와 스펙트럼 요소의 연성으로 인해 많은 연산 시간이 요구된다. 이러한 문제점을 개선하고자, 본 연구에서는 국부적 불연속 구간의 단면이 일정한 경우에 대해 국부적 불연속 구간을 스펙트럴 수퍼 요소로 대체한 SSE/SSE 연성 해석을 시도하였다. 적용 모델로는 국부적 결함을 가진 레일의 파동 반사 및 투과, 그리고 주기적 보강재를 가진 평판의 진동전파에 대해 적용하였다. 결함을 가진 레일의 해석 예를 통해, 본 논문에서 사용한 SSE/SSE 방법과 기존의 SSE/FE 방법의 성능을 비교하였다. 보강재를 가진 평판의 예를 통해서는 반복 구조를 가진 도파관의 파동 전파 특성 해석에 SSE/SSE 방법이 유용함을 확인하였다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1083-1090
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• 2005

Repeated ribs are used on heat exchange surfaces to promote turbulence and enhance convective heat transfer. Applications include fuel rods of gas-cooled nuclear reactors, inside cavities of turbine blades, and internal surfaces pipes used in heat exchangers. Despite the great number of literature papers, only few experimental data concern detailed distributions of friction factors and heat transfer coefficients in square channels varying the number of rough walls. This issue is tackled by investigating effects of different number of ribbed walls on heat transfer and friction characteristics in square channel. The rough wall have a 45$^{\circ}$ inclined square rib. Uniform heat flux is maintained on whole inner heat transfer channel area. The heat transfer coefficient and friction factor values increase with increasing the number of rough walls.