• 한국전산유체공학회지
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• 제2권1호
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• pp.1-7
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• 1997

A FA-FD hybrid method, developed for solving three-dimensional incompressible Navier-Stokes equations, is applied to calculate three-dimensional laminar flows through a square duct with a 90° bend. The method discretizes the convective terms in the primary flow direction with 3rd-order upwind finite-differences and the convective and diffusive terms in the transverse directions with the two-dimensional finite analytic method. The non-staggered grid system is used and the pressure-velocity coupling is achieved by a global iteration procedure based on the PISO algorithm. Detailed comparisons between the computed solutions and the available experimental data are given mainly for the velocity distributions at cross-sections in a 90° bend of a square duct with both fully developed and developing entry flows. Although the computational result shows generally a good agreement with the experimental data, there are some significant discrepancies underlining the necessity of more accurate numerical methods as well as reliable experimental data for their validation.

• 농업과학연구
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• 제47권1호
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• pp.19-28
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• 2020

This study proposed a simple estimation method for irrigation return flow from paddy fields using the water balance model. The merit of this method is applicability to other paddy fields irrigated from agricultural reservoirs due to the simplicity compared with the previous monitoring based estimation method. It was assumed that the unused amount of irrigation water was the return flow which included the quick and delayed return flows. The amount of irrigation supply from a reservoir was estimated from the reservoir water balance with the storage rate and runoff model. It was also assumed that the infiltration was the main source of the delayed return flow and that the other delayed return flow was neglected. In this study, the amount of reservoir inflow and water demand from paddy field are calculated on a daily basis, and irrigation supply was calculated on 10-day basis, taking into account the uncertainty of the model and the reliability of the data. The regression rate was calculated on a yearly basis, and yearly data was computed by accumulating daily and 10-day data, considering that the recirculating water circulation cycle was relatively long. The proposed method was applied to the paddy blocks of the Jamhong and Seosan agricultural reservoirs and the results were acceptable.

• 한국가시화정보학회지
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• 제18권2호
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• pp.18-27
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• 2020

Air lift pump operated by buoyancy is mainly used for the continuous circulation and the purification of fluids. In this study, the computational flow analysis has been performed with the geometric and operating conditions of the air lift pump. The numerical data from the analysis have been verified by comparing with the previous experimental data. The following results are obtained which advance the efficiency of the air lift pump. As the submergence length of pipe increases and the pipe length over the water surface decreases, the non-dimensional mass flow ratio increases in both cases. When the position of the air injection hole is within the pipe, the circulation range of the surrounding fluid becomes widened with the distance between the air injection hole and the pipe inlet relatively becoming narrower. It is more efficient both when the air injection velocity is at 10 m/s and at 15 m/s, and when the diameter of the pipe with holes is doubled near the water surface. It is expected that these results can be provided as fundamental data for operating the air lift pump.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권4호
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• pp.1519-1534
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• 2016

In this paper, we study how to optimize the data shuffle phase by leveraging the flow relationship in datacenter networks (DCNs). In most of the clustering computer frameworks, the completion of a transfer (a group of flows that can enable a computation stage to start or complete) is determined by the flow completing last, so that limiting the rate of other flows (not the last one) appropriately can save bandwidth without impacting the performance of any transfer. Furthermore, for the flows enter network late, more bandwidth can be assigned to them to accelerate the completion of the entire transfer. Based on these characteristics, we propose the flow chasing algorithm (FCA) to optimize the completion of the entire transfer. We implement FCA on a real testbed. By evaluation, we find that FCA can not only reduce the completion time of data transfer by 6.24% on average, but also accelerate the completion of data shuffle phase and entire job.

• 한국조사연구학회지:조사연구
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• 제12권2호
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• pp.27-50
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• 2011

도시의 행정수요 측정과 도시경제 운영을 위해 주간활동인구를 파악해야 할 필요성이 증가하였다. 상주인구를 보완하는 개념으로서 센서스의 통근 통학 자료에 근거를 둔 주간인구가 활용되고 있으나 서비스 경제가 압도적인 서울과 같은 대도시의 주간활동인구 파악에는 한계가 있다. 본 연구에서는 도시의 주간활동인구를 파악하기 위한 개념으로서 유동인구를 제시하고 서울시 유동인구 조사의 방법을 소개하였으며 주요 분석결과를 제시하였다. 유동인구 조사자료의 분석 결과 센서스 기반 주간인구에서는 파악할 수 없었던 시간대별, 공간대별 도시 주간활동인구의 분포를 밝힐 수 있었다. 끝으로 유동인구 조사자료를 통해 파악한 주간인구와 센서스 기반 주간인구를 자치구 수준에서 비교함으로써 유동인구 조사 자료의 주요 특성들을 밝혔다.

• 설비공학논문집
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• 제18권11호
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• pp.881-887
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• 2006

The objective of this study are to analyze the flow characteristics of R22 flowing through EEVs and to develop an empirical correlation to predict the refrigerant flow rate. The mass flow rates of EEVs with different geometries were measured at various condensing temperatures, subcoolings, and EEV openings. Based on the experimental data, an empirical correlation for mass flow predictions in EEVs was developed by modifying the orifice equation. The correlation showed good agreement with the measured data for R22 with average and standard deviations of 1.4% and 6.1%, respectively. Approximately 90% of the measured data were within ${\pm}10%$ of the predictions.

• 한국전산유체공학회지
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• 제13권4호
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• pp.72-79
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• 2008

This study is to investigate the air flow around a sirocco fan which is used in a range hood. The main object of the study is to improve the flow rate of the fan by analysis of unsteady 3-dimensional incompressible flow. Overall analysis is carried out using CFD method. For this, we used a commercial code, SC/Tetra, and used a sliding mesh method to give the same condition as an actual state. First, verification of the CFD results is done by comparing the experimental data with the numerical data for the suction flow rate. It is confirmed that two results are well consistent. Then for the improvent of flow rate, the effect of shape factors such as diameter ratio of fan, geometry of case, cut-off aperture and guide angle of case exit on the suction flow rate was considered. Especially, for a new design of housing, the principle of Archimedes spiral was used. The overall analysis was applied to a new design of housing, and the result showed an increase of flow rate by 10.7%.

• 대한기계학회논문집B
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• 제29권11호
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• pp.1182-1188
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• 2005

An x-ray PIV (Particle Image Velocimetry) technique was developed to measure quantitative information on flows inside opaque conduits and on opaque-fluid flows. At first, the developed x-ray PIV technique was applied to flow in an opaque Teflon tube. To acquire x-ray images suitable for PIV velocity field measurements, refraction-based edge enhancement mechanism was employed using detectable tracer particles. The optimal distance between with the sample and detector was experimentally determined. The resulting amassed velocity field data were in reasonable agreement with the theoretical prediction. The x-ray PIV technique was also applied to blood flow in a microchannel. The flow pattern of blood was visualifed by enhancing the diffraction/interference -bas ed characteristic s of blood cells on synchrotron x-rays without any contrast agent or tracer particles. That is, the flow-pattern image of blood was achieved by optimizing the sample (blood) to detector distance and the sample thickness. Quantitative velocity field information was obtained by applying PIV algorithm to the enhanced x-ray flow images. The measured velocity field data show a typical flow structure of flow in a macro-scale channel.

• 복식문화연구
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• 제31권4호
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• pp.452-466
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• 2023

This study focused on how retail tech promotes differentiated customer experiences in offline fashion stores. The purpose of this study is to determine the effects of the characteristics of fashion retail tech stores on consumers' flow and satisfaction. We surveyed Koreans aged 10 to 50 who had experienced offline fashion retail tech stores. The survey was conducted from April 28, 2023, to May 21, 2023. The total number of survey respondents was 200. The quantitative data collected through questionnaires was analyzed using SPSS 25.0. To reveal the effects of fashion retail tech store characteristics on consumer's flow and satisfaction, frequency analysis, we conducted frequency analysis, factor analysis, reliability analysis, correlation analysis, and regression analysis. The results of this study, figured out that fashion retail tech store's characteristics, including playfulness, efficiency, interaction, and information provision, have a significant impact on behavior flow, emotional flow, and satisfaction. As a result of analyzing the influence of consumers' flow led to satisfaction, it was confirmed that emotional flow positively influenced satisfaction, but behavioral flow had no meaningful effect on satisfaction. The results of our study can be used to make a successful marketing strategy and can serve as foundational data for consumer research on retail-tech-applied offline fashion stores.

• 한국프랜차이즈경영연구
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• 제15권2호
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• pp.17-37
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• 2024

Purpose: This study used the SOR model to analyze the impact of live commerce's modified livecommercescape factors (interactivity, presence, playfulness, convenience, and broadcaster characteristics) on repurchase intention through usefulness and flow. Research design, data, and methodology: 1,149 respondents with live commerce purchase experience were collected through an online survey, and the collected data was analyzed with SPSS 25.0 and SmartPLS 4.0 statistical package programs. Results: Presence and playfulness were found to have the highest influence on flow and usefulness. In particular, Presence and broadcaster characteristics were found to be the factors that had the greatest influence on flow. Playfulness was found to have the greatest impact on usefulness, and two-way communication was found to have the lowest influence among the five servicescape factors. Broadcaster characteristics also affect flow but not usefulness, and convenience only affects usefulness and does not affect flow. Flow shows results that affect usefulness and repurchase intention. Conclusion: Our findings provide a richer understanding of causal relationships within the SOR framework, demonstrating that broadcaster characteristics, two-way communication, presence, and playfulness can influence flow, perceived usefulness, and, consequently, consumer purchasing behavior.