• Proceedings of the KSME Conference
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• 2001.06d
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• pp.759-764
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• 2001

Heat (mass) transfer characteristics have been investigated on the endwall of a large-scale linear turbine cascade passage under a combustor-level high free-stream turbulence with a large length scale. Local heat (mass) transfer coefficients are measured by using the naphthalene sublimation technique. The result shows that local heat (mass) transfer on the endwall is greatly enhanced in the central region of the turbine passage, but there is no noticeable change in the local heat (mass) transfer in the region suffering severe heat load. Under the high free-stream turbulence, the local heat (mass) transfer coefficient shows more uniform distribution and its average value across the whole endwall region is increased by 26% of that at low turbulence condition. The heat (mass) transfer data on the endwall strongly supports that well-organized vortices near the endwall tends to suffer an suppression by the high free-stream turbulence.

• Journal of the Korean Institute of Rural Architecture
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• v.17 no.2
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• pp.51-58
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• 2015

10 years ago, in Sijeon-ri, Dogo-myeon, Asan-si, the existing stream was repaired to develope Mt. Dogo trail and irrigation systems through road expansion pavement construction and small stream repair construction. The trees such as persimmon and willow are eliminated that rowed on both sides of the stream and dredging work to dig the rock and sand have been performed. As a result, wide asphalt road was built, also flood damage worries were reduced. 10 years passed and now, how did local residents think about the stream repaired before and after? Village residents, public officials, and the stream construction engineer were interviewed. Villagers indicated a problems that brook became a place where water peppers were taking over and water was stagnating due to the slow velocity so nothing could live and natural landscape like a wash place and the cascade disappeared, because rock and sand were taken out brought soil into the brook. Public officials and engineers were aware of the problems at the time of the stream. Now that construction is completed after 10 years, Both realistically and budgetary to restoration would be difficult. However, it is necessary to seek for waterfront space which can be restored or replaced by a part of the stream like similarly before. In addition, it is necessary to restore to the progression of a natural stream which connect with stairs(or slope) - small waterfalls - pools - wash place. In this paper, we hope to take a lesson from the Sijeon-ri model and make rural stream construction be prepared with consideration about not only distinct characteristics of specific area but also the opinion of local resident.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.89-98
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• 2009

This study determines the stream mean slope, stream slope and longitudinal stream profile based on the concept of informational entropy. Maximizing the entropy will make the probability distribution of longitudinal stream profile as uniform as possible while satisfying the constraints. Using this relationships the mean stream slope, stream slope and longitudinal stream profile formulas were derived. The parameters of the applied streams were estimated by the least square method using the geomorphological factors of Dalchon stream basin obtained from Chungcheong Buk-Do local stream consolidation scheme drawings. The comparative investigation was performed between the observed and simulated mean stream slope and longitudinal stream profile, and are in good agreement with the measured data. It is noted that this results can be used in the estimation of stream mean slope and longitudinal stream profile.

• Journal of Mechanical Science and Technology
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• v.18 no.8
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• pp.1435-1450
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• 2004

Experimental data are presented which describe the effects of a combustor-level high free-stream turbulence on the near-wall flow structure and heat/mass transfer on the endwall of a linear high-turning turbine rotor cascade. The end wall flow structure is visualized by employing the partial- and total-coverage oil-film technique, and heat/mass transfer rate is measured by the naphthalene sublimation method. A turbulence generator is designed to provide a highly-turbulent flow which has free-stream turbulence intensity and integral length scale of 14.7% and 80mm, respectively, at the cascade entrance. The surface flow visualizations show that the high free-stream turbulence has little effect on the attachment line, but alters the separation line noticeably. Under high free-stream turbulence, the incoming near-wall flow upstream of the adjacent separation lines collides more obliquely with the suction surface. A weaker lift-up force arising from this more oblique collision results in the narrower suction-side corner vortex area in the high turbulence case. The high free-stream turbulence enhances the heat/mass transfer in the central area of the turbine passage, but only a slight augmentation is found in the end wall regions adjacent to the leading and trailing edges. Therefore, the high free-stream turbulence makes the end wall heat load more uniform. It is also observed that the heat/mass transfers along the locus of the pressure-side leg of the leading-edge horseshoe vortex and along the suction-side corner are influenced most strongly by the high free-stream turbulence. In this study, the end wall surface is classified into seven different regions based on the local heat/mass transfer distribution, and the effects of the high free-stream turbulence on the local heat/mass transfer in each region are discussed in detail.

• Hwankyungkyoyuk
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• v.20 no.4
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• pp.12-26
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• 2007

The purpose of this research is to develop a water environmental education (EE) program using streams, based on the core ideas of ENVISION and materializing elements that were extracted in this research. This research realized the elements and presented a model of the water EE program using a local stream. First, this research developed a basic model of a water EE program using streams by extracting 10 materializing elements and realizing the elements in 4 stage-procedural model. The 10 materializing elements were 1. experiencing the process of inquiry, 2. inquiring local environments, 3. self-directing learning and mutual interaction with colleagues, 4. collecting real data and interpreting, 5. utilizing the ICT(information and communication technology), 6. inquiring with the view point of the 'Environmental Studies for EE', 7. inquiring with the watershed concept, 8. inquiring with the integrating and the holistic view point, 9. pursuing the macroscopic understanding about environment, and 10. connecting the real world phenomena with the environmental concepts and theories. This research materialized these 10 elements in 4 stage model, following the previous ENVISION research, which are 1. preparing stage and visual assessment, 2. writing the report of the inquiry plan, 3. collecting the real data in the environment and performing the investigation, and 4. presenting the inquiry results. Second, with using this basic model, this research developed and presented a model of the specific water EE program using a case stream called 'Baig Cheon' stream, which is a local stream. This research is considered to have a considerable meaning in developing a EE program with ENVISION ideas for the watershed concept and inquiry with environmental science using local streams. The developed model can help the professional development of teachers and teacher education of water EE.

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.775-779
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• 2011

As the technology of multimedia sensor networks is desired in large numbers of applications nowadays, real-time service becomes one of the most important research challenges. Even though lots of related works have been conducted to meet this requirement in several ways, the specific traffic model for real-time has not been taken yet. Thus, it causes lack of adaptability of those approaches in real deployment. To solve this problem, in this paper, we model the application via (m,k)-firm streams which have weakly hard real-time property. And then, a novel forwarding scheme based on modified DBP (Distance-Based Priority) is proposed by considering local-DBP and stream DBP together. Local-DBP can contribute to identify the detailed causes of unsatisfied quality, that is, network congestion or wireless link failure. Simulation results reveal that (m,k)-firm is a good traffic model for multimedia sensor networks and the proposed scheme can contribute to guarantee real-time requirement well.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.133-140
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• 1998

A Navier-Stokes code based on a unstructured finite volume method is used to simulate the MIT flapping foil experiment. A low Reynolds number $k-{\varepsilon}$ turbulence model is used to close the Reynolds averaged Navier-Stokes equations. Computations are carried out for a domain involving two flapping foils and a downstream hydrofoil. The computational domain is meshed with unstructured quadrilateral elements, partly structured. Numerical solutions show good agreement with experiment. Unsteadiness inside boundary layer is entrained when a unsteady vortex impinge on the blade surface. It shoves that local peak value inside the boundary layer and also local minimum near the edge of boundary layer as it developes along the blade surface. The unsteadiness inside the boundary layer is almost isolated from the free stream unsteadiness and being convected at local boundary layer speed, less than the free stream value.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.3
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• pp.186-196
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• 1991

Numerical analysis has been performed to investigate the effects of the turbulence intensity and Prandtl number on the local heat transfer around a circular cylinder in crossflow. The governing equations were reformulated in a non-orthogonal coordinate system with Cartesian velocity components and discretised by the finite volume method with a non-staggered variable arrangement. For laminar flow, the calculations were performed for the Reynolds numbers 26 and 200. The results showed good agreement with the experimental results. For turbulent flow of the Reynolds number $1{\times}10^5$ and $2{\times}10^6$, the results showed that with an increase in the turbulent intensity in the main stream, the local Nusselt number increases in the front region of the circular cylinder. But the effect of turbulent intensity on the local Nusselt number diminishes in the wake region. The influence of Prandtl numbers show similar trend to that of turbulent intensity.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2062-2072
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• 1991

The effect of free stream turbulence on the flow characteristics behind a circular cylinder is investigated in the present experimental study. The various free stream turbulent intensities are generated by different combinations of cylinder locations and grid shapes. Split film sensor with constant temperature anemometer is used to measure the local instantaneous velocity components. Experimental results demonstrate the large scale coherent structures are rapidly distorted and the Strouhal number is decreased with increasing free stream turbulent intensity.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.389-392
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• 2002

Local Mechanical work is researched which spending unnecessary labors and time due to unnecessary material accumulation and fabricated on site. Accordingly, this study analyzes the work process of mechanical equipments by Lean Production principles. Value Stream Analysis(VSA) uncovers waste factor of the existing method and manufactory production method using Value Stream Mapping(VSM). In the results, this study presents improvement of the existing method problems and negative factors of manufactory production.