• Title/Summary/Keyword: Max-Flow

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Genetic Diversity in Korean Populations of Glycine soja (Fabaceae)

  • Myong Gi Chung
    • Journal of Plant Biology
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    • v.38 no.1
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    • pp.39-45
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    • 1995
  • Glycine soja Sieb. et Zucc., a predominantly selfing annual, has been served as a reservoir of germplasm for soybean, G. max (L.) Merr., cultivar improvement. This study describes the levels and distribution of genetic variation within and among 22 Korean populations of G. soja using starch gel electrophoresis. The species maintains very similar levels of genetic variability within populations observed in most other annuals. At the population level, the mean percent of polymorphic loci (P) was 32.6%, mean number of allele per locus (A) was 1.32, and mean expected heterozygosity (He) was 0.112. In addition, total genetic diversity (HT) calculated only for polymorphic loci was 0.347. However, significant differences in allele frequencies among populations were found for all loci (P<0.001 in each case) and, on average, about 70% of the total variation in the species is common to all populations. Indirects estimate of the number of migrants per generation (Nm=0.58, calculated from mean GST) indicates that gene flow is low among Korean populations of the species. In addition, analysis of fixation indices revealed a substantial heterozygote deficiency in most populations and at all loci. This indicates that most populations sampled may have been substructed largely due to inbreeding (predominantly selfing) and restricted gene flow, coupled with founder effect and genetic drift. Considering a high genetic divergence among populations, it is recommended that several Korean populations of the species should be preserved, especially such as populations in the eastern and southeastern Korean peninsula with high variation.

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Study on Film Boiling Heat Transfer of Spray Cooling in Air-Water Full Cone Spray System (물-공기 원추형 분무시스템에 있어서 분무냉각 막비등 열전달에 관한 연구)

  • Kim, Yeung-Chan;Yun, Seung-Min
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.12 s.255
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    • pp.1236-1242
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    • 2006
  • The local heat flux of spray cooling in the film boiling region were experimentally investigated for the spray region of $D_{max}$ = $0.005{\sim}0.03m^3/(m^2s)$. A twin-fluid full cone spray nozzle was employed for the experiment and the distributions of droplet flow rates were obtained for air-water full cone sprays. A stainless steel block was cooled down from initial temperature of about $800^{\circ}C$ by full cone spray. In the region near the stagnation point, it was found that the experimental data are in good agreement with the results predicted from the correlations between the local heat transfer and the local droplet flow rate proposed in the previous report. However, it was found that the experimental data of $D_r$ > $0.01m^3/(m^2s)$ are a little smaller than the results predicted from the correlations.

Accurate quantitative assessment of grouting efficiency in fractured rocks by evaluating the aperture sizes of fractures (절리암반내 그라우팅 성과에 대한 정량적인 판단기법 개발)

  • 김중열;김유성;김형수;백건하;김기석
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.03a
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    • pp.695-702
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    • 2002
  • Groundwater flow is primarily influenced by the presence of fractures, functioning as conduits. To block the flow, grouting operation is commonly used. Thereby the fractures are then expected to be sealed, which will add to enhance the shear strength in rock. This far, regarding the assessment of grouting efficiency, however, there's been a considerable uncertainty That is, several geophysical methods of high resolution such as tomography, S-wave logging have produced a significant amount of measurable response caused by grouting, but they can inevitably be used only for the qualitative assessment. Thus, this paper deals with an accurate quantitative assessment about the grouting result. In this, a new strategy is introduced, based mainly on evaluating the opening of fractures. For fracture-opening investigation purposes, borehole Televiewer has already proven to be an excellent logging technique that produces both amplitude image and traveltime image. As well known, the traveltime image can be converted to a high precision 3D caliper log with max. 288 arms, which allows to observe the opening of fractures. To evaluate the fracture opening from the traveltime image, an algorithm of practical use was developed, in which image correction due to the borehole deviation, feature discrimination of wall roughness from fractures, automatic evaluation procedure etc. were considered. Field examples are shown to confirm the efficiency of the suggested method.

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Remote Sensing Image Segmentation by a Hybrid Algorithm (Hybrid 알고리듬을 이용한 원격탐사영상의 분할)

  • 예철수;이쾌희
    • Korean Journal of Remote Sensing
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    • v.18 no.2
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    • pp.107-116
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    • 2002
  • A hybrid image segmentation algorithm is proposed which integrates edge-based and region-based techniques through the watershed algorithm. First, by using mean curvature diffusion coupled to min/max flow, noise is eliminated and thin edges are preserved. After images are segmented by watershed algorithm, the segmented regions are combined with neighbor regions. Region adjacency graph (RAG) is employed to analyze the relationship among the segmented regions. The graph nodes and edge costs in RAG correspond to segmented regions and dissimilarities between two adjacent regions respectively. After the most similar pair of regions is determined by searching minimum cost RAG edge, regions are merged and the RAG is updated. The proposed method efficiently reduces noise and provides one-pixel wide, closed contours.

Vehicle-induced aerodynamic loads on highway sound barriers part 2: numerical and theoretical investigation

  • Wang, Dalei;Wang, Benjin;Chen, Airong
    • Wind and Structures
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    • v.17 no.5
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    • pp.479-494
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    • 2013
  • The vehicle-induced aerodynamic loads bring vibrations to some of the highway sound barriers, for they are designed in consideration of natural wind loads only. As references to the previous field experiment, the vehicle-induced aerodynamic loads is investigated by numerical and theoretical methodologies. The numerical results are compared to the experimental one and proved to be available. By analyzing the flow field achieved in the numerical simulation, the potential flow is proved to be the main source of both head and wake impact, so the theoretical model is also validated. The results from the two methodologies show that the shorter vehicle length would produce larger negative pressure peak as the head impact and wake impact overlapping with each other, and together with the fast speed, it would lead to a wake without vortex shedding, which makes the potential hypothesis more accurate. It also proves the expectation in vehicle-induced aerodynamic loads on Highway Sound Barriers Part1: Field Experiment, that max/min pressure is proportional to the square of vehicle speed and inverse square of separation distance.

Dense Core Formation in Filamentary Clouds: Accretion toward Dense Cores from Filamentary Clouds and Gravitational Infall in the Cores

  • Kim, Shinyoung;Lee, Chang Won;Myers, Philip C.;Caselli, Paola;Kim, Mi-Ryang;Chung, Eun Jung
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.70.3-70.3
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    • 2019
  • Understanding how the filamentary structure affects the formation of the prestellar cores and stars is a key issue to challenge. We use the Heterodyne Array Receiver Program (HARP) of the James Clerk Maxwell Telescope (JCMT) to obtain molecular line mapping data for two prestellar cores in different environment, L1544 in filamentary cloud and L694-2 in a small cloud isolated. Observing lines are $^{13}CO$ and $C^{18}O$ (3-2) line to find possible flow motions along the filament, $^{12}CO$ (3-2) to search for any radial accretion (or infalling motions) toward the cores of gas material from their surrounding regions, and $HCO^+$ (4-3) lines to find at which density and which region in the core gases start to be in gravitational collapse. In the 1st moment maps of $^{13}CO$ and $C^{18}O$, velocity gradient patterns implying the flow of material were found at the cores and its surrounding filamentary clouds. The infall asymmetry patterns of HCO+ and $^{13}CO$ line profiles were detected to be good enough to analyze the infalling motions toward the cores. We will report further analysis results on core formation in the filamentary cloud at this meeting.

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Enhancement of Regression Rate of Hybrid Rocket Fuel by Oxidizer Injection Condition (산화제 유입조건에 따른 하이브리드 로켓 연료의 연소율 향상)

  • Hwang Youngchun;Lee Changjin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • v.y2005m4
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    • pp.66-71
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    • 2005
  • In this study the regression rate of hybrid rocket fuel has been investigated by two methods. First method is to use swirl injectors for enhancement of regression rate. And second method is the modification of the helical grain deriving improvement of combustion area and generating swirl flow. Tests have been done with PMMA and gaseous oxygen. In this paper the incline angle of the helical grain was varied to find the optimal condition to obtain the max regression rate for a given operational condition.

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Enhancement of hybrid rocket regression rate by swirl flow and helical grain configuration (선회류와 나선형 그레인 형상을 이용한 하이브리드 로켓의 연소율 향상)

  • Hwang Young-Chun;Lee Chang-Jin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2005.11a
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    • pp.318-322
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    • 2005
  • In this study the regression rate of hybrid rocket fuel has been investigated by swirl injectors and helical grains. Tests have been done with two kinds of injector and helical grain. In this paper the swirl injector and helical grain were varied to find the optimal condition to obtain the max regression rate for a given operational condition.

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Die-Sinking Electrical Discharge Machining with Dielectric Fluid Ejection System through the Inside of the Electrode (전극봉내 방전유 분산시스템에 의한 형조방전기공)

  • 왕덕현;우정윤
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.1
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    • pp.71-77
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    • 2001
  • Experimental study if die-sinking electrical discharge machining(EDM) was conducted with rotating electrode system including inside hole for increasing the material removal rate(MRR). With the help of dielectric fluid flow through the inside according to the different internal diameter of the hole, the molten workpiece debris could be removed and flushed out during the EDM, Cold die alloy(SKD-1) was executed for different peak current and duty factor. From this study, the MRR was found to be increased with the peak current. The more MRR was obtained for the case of electrode inside diam-eter of 10 mm, but the MRR was decreased as the diameter near at the 4mm and 6mm. The values of surface roughness and roundness were analyzed under various conditions, and these were affected by the inside diameter change of electrode.

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최적관리제어

  • 이문상;조광현;임종태
    • ICROS
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    • v.6 no.4
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    • pp.38-48
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    • 2000
  • Abstract :본 논문에서는 관리제어시스템의 동적특성을 허용언어(admissible language) 범위 이내에서 최적화시키는 최적 관리제어기법들을 소개한다. 본 논문에서 주로 다루고자 하는 최적 관리제어기법은 Kumar와 Garg에 의해 제안된 기법과 Cho와 Lim에 의해 제안된 계층적 최적 관리제어기법, 그리고, Sengupta와 Lafortune이 제안한 최적 관리제어기법 등이다. 첫 번째 기법에서는 우선 시스템의 최적화를 위해 고려되고 있는 비용함수(cost function)를 소개한 후, 최대흐름 최소분할생성 정리(max-flow min-cut theorem)를 이용한 최적 관리제어기 설계기법을 제시하고, 이를 부분관측 하에서도 최적 관리제어기를 설계할 수 있도록 확장한다. 그런 후 제시된 설계기법에 의해 설계된 관리제어시스템에서 발생 할 수 있는 문제점들을 지적하고, Cho와 Lim에 의해 제안된 완전 최소분할생성(complete min-cut)이라는 개념을 도입하여 지적된 문제점들을 해결할 수 있는 방법을 제시한다. 또한 시스템의 고장을 고려한 계층적 최적 관리 제어(layered optimal supervisory control)기 법을 소개한다 그리 고 마지막으로 Sengupta와 Lafortune이 제안한 최적 관리제어기법에 대해서 살펴본다.

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