• Title/Summary/Keyword: flow domain

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Numerical Simulation on Hydrodynamic Characterization Changes Associated with the Construction of Dikes and Dredging Operations in Saemangeum Lake (새만금호 내 방수제 공사 및 준설에 의한 수리동역학적 특성 변화 수치 모델링)

  • Oh, Chan-Sung;Choi, Jung-Hoon;Cho, Young-Kweon
    • Journal of Environmental Science International
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    • v.22 no.9
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    • pp.1115-1129
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    • 2013
  • The study area is located on the western coast, and the inner development construction has been ongoing since 2011. The purposes of current study are to effectively simulate and quantitatively predict a temporal and spatial distributions of water temperature and salinity due to the stages of inner development construction in saemangeum reclaimed area. The transient-state numerical modeling using EFDC model is done, and the numerical simulation results are validated reasonably by repetitive numerical model calibration procedures with respect to field measurements of water temperature and salinity. The spatial distributions of water temperature and salinity show similar trends before and after construction of the dikes. In spring season, the salinity has maximum value of 21 psu, while, in summer season, the salinity shows 7 psu in a whole modeling domain. Thus, it is clearly observed that salt water is replaced by freshwater. However, the salinity and temperature reach their initial conditions at the end of the year. The salinity after construction of the dikes is lower than that before construction of them at Mankyeong area. On the other hands, after construction of the dikes, the salinity after dredging operations is higher than that before dredging. Because drastical increasing of water volume in Saemangeum Lake leads to increasing of stagnation time at bottom layer, and salt water is easily intruded to the two estuaries. Therefore, it may be concluded that hydrodynamic characteristics on Saemangeum are dominated by either Mankyeong and Dongjin discharge or sluice gates in/out-flow amounts, and thus they must be properly considered when rigorous and reasonable predictions of water temperature and salinity according to the stages of inner development construction.

An Implementation of Mathematics Editor Using SGML Notation (SGML 표기법을 이용하는 수식 편집기의 설계 및 구현)

  • Kim, Tae-Hoon;Hyun, Deuk-Chang;Lee, Soo-Youn
    • The Transactions of the Korea Information Processing Society
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    • v.3 no.5
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    • pp.1082-1092
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    • 1996
  • The design of distrbuted systems is difficult to achieve as the execution patterns of distrbuted systems are typically more complex than those of non- distributed systems. Thus, research toward the development of design methods for distributed systems is quitely needed. As object-oriented systems and distrbuted systems share similar properties, the combination of these two is somehow natural. In this work, a design of distributed systems is introduced. The goal of the method in this paper is to provide assistance to the process of specifying a formal object- oriented specification from graphical representation specification inputs such as data flow diagrams, state transition diagrams and Petri nets. It addresses the extraction of objects, operations and reationshipsfrom the problem domain with emphasis on the specification of the characteristics of distributed systems. This object identification method is supported by a knowledge base that provides for the automated analysis and reasoning about objects and their relationsships. The final object model is represented in a format which provides a formal mechanism for reprsenting the object information.

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Integrated Modeling of Distributed Object-Oriented Systems (다수모델을 이용한 객체지향적 분산처리 시스템의 디자인 방법)

  • Lee, Sang-Bum
    • The Transactions of the Korea Information Processing Society
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    • v.3 no.5
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    • pp.1103-1111
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    • 1996
  • The design of distrbuted systems is difficult to achieve as the execution patterns of distrbuted systems are typically more complex than those of non- distributed systems. Thus, research toward the development of design methods for distributed systems is quitely needed. As object-oriented systems and distrbuted systems share similar properties, the combination of these two is somehow natural. In this work, a design of distributed systems is introduced. The goal of the method in this paper is to provide assistance to the process of specifying a formal object- oriented specification from graphical representation specification inputs such as data flow diagrams, state transition diagrams and Petri nets. It addresses the extraction of objects, operations and reationshipsfrom the problem domain with emphasis on the specification of the characteristics of distributed systems. This object identification method is supported by a knowledge base that provides for the automated analysis and reasoning about objects and their relationsships. The final object model is represented in a format which provides a formal mechanism for reprsenting the object information.

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Channel Estimation Method Using the Correlation in the High-Speed Wireless Transmissions (고속 무선 전송에서 상관관계를 이용한 채널 추정방식)

  • Lee Joo-Hyoung;Kim Joo-Kyoung;Kim Jae-Moung
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.4 no.1 s.6
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    • pp.63-71
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    • 2005
  • This paper proposes the channel estimation method robust to severe frequency selective fading channels in O%M system using wide bandwidth for the high data rate transmission. DDCE, which uses data between the high correlated symbols, is usually used for channel estimation in the slow fading channels. DDCE can get high gains in the non-selective channels. As the bandwidth of system gets wider, it becomes more severe frequency selective fading environments so that the reliability of data becomes lower and error flow is occurred. FE method, this paper proposed, uses the relation between sub-carriers of OFDM in frequency selective fading channels so FE method gets some gains by adapting the power value at a target frequency to the mean value of channel estimated values of adjacent sub-carriers. Because FE uses only preamble unlike DDCE using data, it is independent of data rate related to the reliability of data and the number of multipath. Consequently, FE can obtain considerable gains in the wideband systems where the errorflow of DDCE is occurred, and FE is applicable to frequency selective fading environments.

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Study on Efficient Adaptive Controller for Attenuation of Engine Noises in a Car (자동차의 엔진소음 감쇠를 위한 효율적인 적응제어기에 대한 연구)

  • Kwon, Oh-Sang
    • The Journal of the Korea institute of electronic communication sciences
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    • v.9 no.9
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    • pp.983-989
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    • 2014
  • In this paper, a new active noise control method was proposed to decrease a weight of car, and to increase a fuel efficiency and to provide passengers' comfort and calmness, instead of a passive noise control method such as sound absorbing and insulating materials. The proposed method is an enhanced active noise controller operating by a bidirectional control algorithm. The algorithm is simple to implement and available to analyze mathematically with nearly equivalent complexity of computation. Through simulations for engine noises of a car, the proposed controller was verified that its performances of time and frequency domain were superior to those of both feedforward and feedback controllers, and it had better capability of controlling the noises when the impulsive disturbance was flow in and the response of secondary path was varied.

A Numerical Study on Spatial Behavior of Linear Absorbing Solute in Heterogeneous Porous Media (비균질 다공성 매질에서 선형 흡착 용질의 공간적 거동에 대한 수치적 연구)

  • Jeong, Woo Chang;Lee, Chi Hun;Song, Jai Woo
    • Journal of the Korean GEO-environmental Society
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    • v.4 no.3
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    • pp.79-88
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    • 2003
  • This paper presents a numerical study of the spatial behavior of a linear absorbing solute in a heterogeneous porous medium. The spatially correlated log-normal hydraulic conductivity field is generated in a given two-dimensional domain by using the geostatistical method (Turning Bands algorithm). The velocity vector field is calculated by applying the two-dimensional saturated groundwater flow equation to the Galerkin finite element method. The simulation of solute transport is carried out by using the random walk particle tracking model with CD(constant displacement) scheme in which the time interval is automatically adjusted. In this study, the spatial behavior of a solute is analyzed by the longitudinal center-of-mass displacement, longitudinal spatial spread moment and longitudinal plume skewness.

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Numerical Study on Aerodynamic Lift on Windshield Wiper of High-Speed Passenger Vehicles (자동차 고속 주행시 와이퍼 부상현상에 대한 수치해석 연구)

  • Lee, Seung-Ho;Lee, Sung-Won;Hur, Nahm-Keon;Choi, Woo-Nyoung;Sul, Jin-Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.4
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    • pp.345-352
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    • 2011
  • In the present study, a three-dimensional CFD simulation on aerodynamic lift acting on windshield wiper blades was performed to improve the wiping performance of a vehicle moving at a high speed. To predict the reliable flow characteristics around the windshield wiper system, the computational domain included the full vehicle model with detailed geometry of wiper blades in the wind tunnel. From the numerical results, the drag and lift coefficients of wiper blade were obtained for the performance of windshield wiper. With this aerodynamic characteristics of windshield wiper, the effects of wiping angles and hood tip angle on the wiping performance of the windshield wiper were evaluated.

Plasma Peptidome as a Source of Biomarkers for Diagnosis of Cholangiocarcinoma

  • Kotawong, Kanawut;Thitapakorn, Veerachai;Roytrakul, Sittiruk;Phaonakrop, Narumon;Viyanant, Vithoon;Na-Bangchang, Kesara
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.3
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    • pp.1163-1168
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    • 2016
  • Cholangiocarcinoma (CCA) is the bile duct cancer which constitutes one of the important public health problems in Thailand with high mortality rate, especially in the Opisthorchis viverrini (a parasite risk factor for CCA) endemic area of the northeastern region of the country. This study aimed to identify potential biomarkers from the plasma peptidome by CCA patients. Peptides were isolated using 10 kDa cut-off filter column and the flow-through was then used as a peptidome for LC-MS/MS analysis. A total of 209 peptides were obtained. Among these, 15 peptides were concerned with signaling pathways and 12 related to metabolic, regulatory, and biosynthesis of secondary metabolite pathways. Five exclusive peptides were identified as potential biomarkers, i.e. ETS domain-containing transcription factor ERF (P50548), KIAA0220 (Q92617), phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit beta isoform isoform 1 (P42338), LP2209 (Q6XYC0), and casein kinase II subunit alpha (P19784). Three of these biomarkers are signaling related molecules. A combination of these biomarkers for CCA diagnosis is proposed.

A Review of the Possible Causes of Negative Source Impedance in Fluid Machines (유체기계에 있어서 부의 음원 임피던스의 원인에 관한 고찰)

  • ;Keith S. Peat
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.3
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    • pp.76-82
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    • 2001
  • Most fluid machines can be considered as periodic noise sources when operated under constant conditions, which allows for a frequency domain representation of the source and the associated acoustic field In the duct. In such a representation, the source is characterized by frequency-dependent values of both strength and impedance. Although knowledge of these values can be gained by either experimentation or by modeling, one-port acoustic characteristics of an in-duct source with high flow velocity, high temperature, and high sound level can be measured only by the multiload method using an overdetermined set of open pipes with different lengths as applied loads. However, the problem is that negative source resistances have been often measured. This paper reviews the possible causes of the problem, with reference to experimental and theoretical results, in an attempt to clarify the issue. A new interpretation is given for the violation of basic assumptions and the defect in the algorithm of multiload method. The major cause and mechanism of the problem is due to the violation of time invariance assumption of the source and the load impedance can seriously affect the final measured result of source impedance.

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Knockdown of UHRF1 by Lentivirus-mediated shRNA Inhibits Ovarian Cancer Cell Growth

  • Yan, Feng;Shao, Li-Jia;Hu, Xiao-Ya
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.4
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    • pp.1343-1348
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    • 2015
  • Human UHRF1 (ubiquitin-like PHD and RING finger domain-containing 1) has been reported to be over-expressed in many cancers, but its role in ovarian cancer remains elusive. Here, we determined whether knockdown of UHRF1 by lentivirus-mediated shRNA could inhibit ovarian cancer cell growth. Lentivirus-mediated short hairpin RNAs (lv-shRNAs-UHRF1) were designed to trigger the gene silencing RNA interference (RNAi) pathway. The efficiency of lentivirus-mediated shRNA infection into HO-8910 and HO-8910 PM cells was determined using fluorescence microscopy to observe lentivirus-mediated GFP expression and was confirmed to be over 80 percent. UHRF1 expression in infected HO-8910 and HO-8910 PM was evaluated by real-time PCR and Western blot analysis. The Cell Counting Kit-8 (CCK-8) assay was used to measure cell viability; flow cytometry and Hoechst 33342 assay was applied to measure cell cycle arrest and apoptosis. Cell invasion was assessed using transwell chambers. Our results demonstrated that the loss of UHRF1 promoted HO-8910 and HO-8910 PM cell apoptosis, while inhibiting cell proliferation. In addition, UHRF1 knockdown significantly inhibited the invasion of human ovarian cancer cells. In the present study, we also showed that depleting HO-8910 cells of UHRF1 caused activation of the DNA damage response pathway, with the cell cycle arrested in G2/M-phase. The DNA damage response in cells depleted of UHRF1 was illustrated by phosphorylation of CHK (checkpoint kinase) 2 on Thr68, phosphorylation of CDC25 (cell division control 25) on Ser 216 and phosphorylation of CDK1 (cyclin-dependent kinase 1) on Tyr 15.