• Title/Summary/Keyword: Cellular flow

Search Result 359, Processing Time 0.025 seconds

A Plan to guarantee quality of Light-weight Cellular Concrete for floating floor (뜬바닥용 기포콘크리트의 품질확보 방안)

  • 이성호;정갑철
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2003.11a
    • /
    • pp.938-943
    • /
    • 2003
  • The characteristics of lightweight cellular concrete has much influence on the compressive strength and flow from the design of mixture. This study is to investigate the characteristics of the compressive strength and flow for the mixture of lightweight cellular slurry. KS F 4039 was compared to the construction system and quality for lightweight cellular comcrete of floating floor. As the result of this study, the standard of the compression strength for target slurry have to lower and an upper limit of flow was judged to be 230mm

  • PDF

Design of Cellular Layout based on Genetic Algorithm (유전 알고리즘에 기초한 셀 배치의 설계)

  • Lee, Byung-Uk;Cho, Kyu-Kap
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.16 no.6
    • /
    • pp.197-208
    • /
    • 1999
  • This paper presents an operation sequence-based approach for determining machine cell layout in a cellular manufacturing environment. The proposed model considers the sequence of operations in evaluating the intercell and intracell movements. In this paper, design of cellular layout has an objective of minimization of total material flow among facilities, where the total material flow is defined as a weighted sum of both intercell and intracell part movements. The proposed algorithm is developed by using genetic algorithm and can be used to design an optimal cellular layout which can cope with changes of shop floor situation by considering constraints such as the number of machine cells and the number of machines in a machine cell.

  • PDF

Multi-Cellular Natural Convection in the Melt during Convection- Dominated Melting

  • Kim, Sin;Kim, Min-Chan
    • Journal of Mechanical Science and Technology
    • /
    • v.16 no.1
    • /
    • pp.94-101
    • /
    • 2002
  • Convection-dominated melting in a rectangular cavity is analyzed numerically with particular attention to the multi-cellular flows in the melt. At the earlier stage of the melting, the melt region is quite similar to a cavity with high aspect rati71, where the multi-cellular natural convection appears. Numerical results show that the formation and evolution of the multiple flow cells in the melt region is approximately similar to t]tat of a single-phase flow in a tall cavity with the same aspect ratio; however, the continuous change of the melt region due to the melting affects the detailed process. Also, numerical aspects for the prediction of the detailed flow structure in the melt are discussed.

Multiparameter Flow Cytometry: Advances in High Resolution Analysis

  • O'Donnell, Erika A.;Ernst, David N.;Hingorani, Ravi
    • IMMUNE NETWORK
    • /
    • v.13 no.2
    • /
    • pp.43-54
    • /
    • 2013
  • Over the past 40 years, flow cytometry has emerged as a leading, application-rich technology that supports high-resolution characterization of individual cells which function in complex cellular networks such as the immune system. This brief overview highlights advances in multiparameter flow cytometric technologies and reagent applications for characterization and functional analysis of cells modulating the immune network. These advances significantly support highthroughput and high-content analyses and enable an integrated understanding of the cellular and molecular interactions that underlie complex biological systems.

Determining Appropriate Production Conditions in Cellular Manufacturing Systems (셀생산(生産)의 효율적(效率的)인 운용(運用)을 위한 시뮤레이션 연구(硏究))

  • Song, Sang-Jae;Choi, Jung-Hee
    • Journal of Korean Institute of Industrial Engineers
    • /
    • v.19 no.2
    • /
    • pp.23-34
    • /
    • 1993
  • Although there are numerous studies that address the problem of optimal machine grouping and part family classification for cellular manufacturing, little research has been reported that studies the conditions where cellular manufacturing is appropriate. This paper, in order to evaluate and compare the job shop with the GT cellular shop, the performance of those shops were simulated by using SIMAN. We tested the effect of independent variables including changes of product demands, intercell flow level, group setup time, processing time variability, variety of material handling systems, and job properties (ratio of processing time and material handling time). And also performance measures (dependent variables), such as machine utilization, mean flow time, average waiting time, and throughput rate, are discussed. Job shop model and GT cellular shop written in SIMAN simulation language were used in this study. These systems have sixteen machines which are aggregated as five machine stations using the macro feature of SIMAN. The results of this research help to better understand the effect of production factors on the performance of cellular manufacturing systems and to identify some of the necessary conditions required to make these systems perform better than traditional job shops. Therefore, this research represents one more step towards the characterization of shops which may benefit from cellular manufacturing.

  • PDF

Experimental Study of Natural Convection Due to Combined Buoyancy in a Rectangular Enclosure (직각 밀폐용기내의 복합부력에 의한 자연대류에 관한 실험적 연구)

  • 이진호;현명택
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.10 no.2
    • /
    • pp.247-256
    • /
    • 1986
  • An experimental investigation was conducted to study natural convection due to temperature and concentration differences between the two opposite end walls of a rectangular enclosure of aspect ratio 0.2. Flow motion in the enclosure appears as a uni-cell flow pattern for the relatively lower concentration and higher temperature differences and vice versa, while it appears as a multicell flow pattern for the comparable temperature and concentration differences. In the multi-cell flow regime, when the cellular flow motiion is very slow, vertical temperature differences within the cells are negligible while the vertical concentration differences are large. In addition, both the temperature and concentration differences are negligible across the interface between the slowly moving cells. For the fast moving cellular flow motion, on thel contrary, vertical temperature differences within the cells are large while the vertical concentration differences are negligible. In this case, temperature differences are negligible and the concentration differences are large across the interface between the fase moving cells.

Optimization Analysis of Flexible Cellular Manufacturing: Route Selection and Determining the Optimal Production Conditions for Ordered Products (유연한 셀생산을 위한 최적가공경로와 생산조건의 결정)

  • Song, Sang-Jae;Choi, Jung-Hee
    • Journal of Korean Institute of Industrial Engineers
    • /
    • v.18 no.1
    • /
    • pp.47-62
    • /
    • 1992
  • This paper describes a procedure for optimizing the route selection and production conditions in alternate process plans under a cellular manufacturing environment. The type of production is mainly production-to-order which deals with unexpected products as the changes factor. The flexible cellular manufacturing can be viewed as a complete unification of both flexible manufacturing process and flexible production management. The integrated problem for designing flexible cellular manufacturing associated with determining the optimal values of the machining speeds, overtime, and intercell flow is formulated as Nonlinear Mixed Integer Programming(NMIP) in order to minimize total production change cost. This is achieved by introducing the marginal cost analysis into the NMIP, which will compute the optimal machining speed, overtime, intercell flow, and routing. The application of this procedure offers greater flexibility to take advantage of the cellular manufacturing due to the optimum use of resources. A solution procedure for this problem was developed and a numerical example is included.

  • PDF

Shear Stress and Atherosclerosis

  • Heo, Kyung-Sun;Fujiwara, Keigi;Abe, Jun-Ichi
    • Molecules and Cells
    • /
    • v.37 no.6
    • /
    • pp.435-440
    • /
    • 2014
  • Hemodynamic shear stress, the frictional force acting on vascular endothelial cells, is crucial for endothelial homeostasis under normal physiological conditions. When discussing blood flow effects on various forms of endothelial (dys)function, one considers two flow patterns: steady laminar flow and disturbed flow because endothelial cells respond differently to these flow types both in vivo and in vitro. Laminar flow which exerts steady laminar shear stress is atheroprotective while disturbed flow creates an atheroprone environment. Emerging evidence has provided new insights into the cellular mechanisms of flowdependent regulation of vascular function that leads to cardiovascular events such as atherosclerosis, atherothrombosis, and myocardial infarction. In order to study effects of shear stress and different types of flow, various models have been used. In this review, we will summarize our current views on how disturbed flow-mediated signaling pathways are involved in the development of atherosclerosis.

Implementation of Lava Flow Simulation Program Using Cellular Automata (Cellular Automata를 이용한 용암류 모의 프로그램의 구현)

  • Lee, Chung-Hwan;Hong Lee, Dong-jin;Cha, Eui-young;Yun, Sung-Hyo
    • The Journal of the Petrological Society of Korea
    • /
    • v.26 no.1
    • /
    • pp.93-98
    • /
    • 2017
  • In this paper, we propose a lava flow simulation program to predict the range of lava flows area and thickness of lava flows during volcanic eruptions. The map information is represented as a 'cell' with observed values per fixed area such as DEM and a lava flow prediction algorithm using a cellular automata model is performed to predict the flow of lava flows. To obtain quantitative data of lava flows, fluid properties of lava flows are defined as Bingham plastic fluid and derived equation is applied to the rules of cellular automata. To verify the program, we use a 30m resolution DEM provided by USGS. We compared simulation results with real lava flows for the Pu'u'O'o crater area in Hawaii, which has erupted since May 24, 2016.

Changes in Cellular Viability and Peroxidase Activities of Green Algae Selenastrum capricornutum (Chlorophyceae) to Cadmium (카드뮴에 대한 녹조류 Selenastrum capricornutum (Chlorophyceae)의 세포활력도 및 peroxidase 활성도 변화)

  • Choi Eun-Joo;Lee Sang-Goo;Lee Seung-Jin;Moon Sung-Kyung;Park Yong-Seok;Rhie Ki-tae
    • Environmental Analysis Health and Toxicology
    • /
    • v.18 no.4
    • /
    • pp.295-303
    • /
    • 2003
  • Physiological cellular activities responses to cadmium (Cd) exposure in green algae with several reductases activities and viability of the cell were examined. The cell division of green algae, Selenastrum capricornutum treated with 5ppm was significantly decreased than that of normal algae. The mean cell number of normal algal culture was as twice much as than that of algae at 6 days after Cd treatment. The cellular viability of algae was analysed by flow-cytometry with fluorescent dye after esterase reaction on cell membrane. The 85.35% of cellular viability of normal culture was decreased to 34.35% when algae was treated with 5 ppm of Cd at 6 days after treatment. It was considered that those method of flow-cytometry is useful tool for toxicity test on micro-organisms in the respect of identifying cellular viability. Also, the activities of both glutathione peroxidase (GPX) and ascorbate peroxidase (APX), which are indirectly react against oxidative stress through reduction of glutathione by Cd were significantly increased with 25%. It is considered that both GPX and APX are involved in the metabolic pathway of Cd -detoxification with similar portion in Selenasturm capricornutum.