• 대한기계학회논문집
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• 제10권6호
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• pp.823-829
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• 1986

본 연구에서는 와동의 대류속도를 H.H. Brunn의 방법과 달리 측정하였으며, 또 이를 이용하여 와동의 중심들 사이의 간격을 구하고자 한다. 이를 위하여 먼저 포텐셜코어영역(potential core region)과 혼합층영역(mixing layer region)의 경계 및 천이영역(transition region)과 난류영역(turbulent region)경계를 구하여야 한다. 각 영역들의 대체적인 구분은 Fig.1과 같다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.426-432
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• 2004

Large-Eddy Simulation (LES) is applied for the simulation of compressible flat plate boundary with Reynolds number up to 5 X 10$^{5}$ . Numerical examples include shock/boundary layer interaction and boundary layer transition, aiming future application to the analysis of transonic fan/compressor cascades. The present LES code uses hybrid com-pact/WENO scheme for the spatial discretization and compact diagonalized implicit scheme for the time integration. The present code successfully predicted the bypass transition of subsonic boundary layer. As for supersonic turbulent boundary layer, mean and fluctuation velocity of the attached boundary, as well as the evolution of the friction coefficient and the displacement thickness both upstream and downstream of the separation region are all in good agreement with experiment. The separation point also agreed with the experiment. In the simulation of the shock/laminar boundary layer interaction, the dependence of the transition upon the shock strength is reproduced qualitatively, but the extent of the separation region is overpredicted. These numerical examples show that LES can predict the behavior of boundary layer including transition and shock interaction, which are hardly managed by the conventional Reynolds-averaged Navier-Stokes approach, although there needs to be more effort before achieving quantitative agreement.

• Journal of Welding and Joining
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• 제7권3호
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• pp.28-35
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• 1989

It was reported that the toughness for welded region was influenced by various factors such as the gradient for prior austenite grain size, the variation of microhardness and the characteristic microstructure depending on distance from the fusion boundary. Therefore, in order to evaluate the fracture strength of the weldment in which the microstructures change continuously, it is important to assess the peculiar strength of each microstructure in welded region. It was known that the small punch(SP) test technique which was originally developed to study the irradiation damage effect for the structures of nuclear power plant was also useful to investigate the strength evaluating of nonhomogeneous materials. In this paper, by means of a small punch test technique the possibility of evaluating strength of parent and welded region in SS41 and SM53B steels was investigated. The obtained results are summerized as follows: 1) The small punch test which showed markedly the ductile-brittle transition behavior in this experiment may be applied to evaluation for the fracture strength of welded region. 2) It was shown that the ductile-brittle regime lied in Region III(plastic membrane stretching region) of the flow characteristics observed in SP test. 3) The SP test technique which shows a more precipitous energy change transition behavior than the other test technique is able to estimate the more precise transition temperature. 4) It could be seen that in comparision with the structure of parent the structure of weld HAZ in SS41 steel was improved while it in SM53B steel was deteriorated.

• 한국가시화정보학회지
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• 제20권1호
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• pp.29-37
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• 2022

We carried out a laboratory experiment about the thermo-fluidic characteristics of natural convection boundary layer over a vertical heated plate under constant heat flux condition. Particle image velocimetry has been applied to observe the surface convection velocity close to the vertical plate submerged in the water chamber with the condition of Ra = 7 × 10⁹ and Pr = 8.1. The velocity distributions indicate that the distinct stripe-like structures appears in the upstream (earlier transition region) and the distinct negative-positive and Λ(λ)-shaped flow structures in the downstream (mid-transition region). In addition, the temporal variation of spanwise and streamwise velocity is also presented.

• 방송공학회논문지
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• 제26권5호
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• pp.543-552
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• 2021

스토리는 인물들 간의 갈등의 전개와 해소의 흐름에 의해 형성된다. 갈등의 설정, 전개, 해결의 흐름이 스토리이다. 인물 면적은 인물의 감정 또는 상태, 인물 간 관계인물과 환경과의 관계를 묘사하는 중요한 표현 기법이다. 본 논문은 인물 면적의 변화 그래프로부터 갈등의 전환 지점을 검출하는 방법을 제안하는 것이 목적이다. 이를 위해 인물 면적을 계산하여 영화의 인물 면적 변화 그래프를 생성하는 방법과 인물 면적 변화 그래프로부터 갈등 전환 장면을 검출하는 방법을 제시한다. 제안하는 방법의 성능을 검증하기 위해 7개의 영화에 대해 갈등 전환 장면을 추출하는 실험을 진행하여 정확도 73.57%, 재현율 77.26%의 성능 평가 결과를 얻었다. 이를 통해 인물 면적에 기반하여 갈등 전환 장면을 추출하는 것이 가능하다는 것을 증명하였다.

• 한국추진공학회지
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• 제21권6호
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• pp.21-31
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• 2017

본 연구에서는 모드 천이가 발생하는 동안 상세한 유동 특성을 조사하기 위해, 이론분석과 수치해석을 수행하였다. 이론분석은 기존의 기체역학과 종래 보고된 이론식들 재정립하였으며, 수치해석은 2차원 비정상 압축성 Navier-Stokes 방정식을 풀기 위해 fully implicit finite volume scheme을 사용해 수행하였다. 해석의 검증을 위하여 실험 결과와 비교하였다. 격리부 입구 전온도와 수소 연료의 당량비를 변화시키면서 모드 천이에 미치는 영향을 조사하였다. 해석과 실험 결과는 정성적으로 잘 일치하였다. 당량비가 증가하면 스크램제트 모드에서 램제트 모드로 천이가 발생하였다. 이 때, 천이는 당량비에 따라 불연속적으로 나타나며, Non-allowable region이 존재하였다. 한편 격리부 입구에서 전온도의 증가는 모드 천이 경계를 변화시켰다.

• 한국약용작물학회지
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• 제14권3호
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• pp.178-182
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• 2006

둥굴레 유전자원의 유연관계를 위한 기초 자료를 얻고자 둥굴레속 식물 수집종 10종에서 18S ribosomal RNA를 암호화하는 18S rDNA 영역의 염기서열을 결정하고 그 특성을 분석한 결과를 요약하면 다음과 같다. 둥굴레속 10종의 18S rDNA 영역 전체의 길이는 $913{\sim}914bp$로 비슷하였으나, 총 8개 지점에서 염기의 치환 및 결실에 의한 변이가 발생하였다. 전위는 $T{\rightarrow}C$전위가 4개 지점에서 발생하였고, $A{\rightarrow}G$ 전위가 1개 지점에서 발생하였으며, 전좌는 $C{\rightarrow}A$ 전좌가 1개 지점에서 발생하여 전위가 전좌보다 5배 만큼 발생하였다. 결실은 2개 지점에서 발생하였다. 18S rDNA의 염기의 조성은 adenine $23.09{\sim}23.33%$, guanine $23.33{\sim}23.52%$, thymine $25.60{\sim}25.85%$, cytosine $27.38{\sim}27.79%$로 pyrimidine계가 purine계보다 많았다. 18S rDNA의 A + T 함량은 $48.80{\sim}49.18%$로 평균 48.99%였고, G+C 함량은 $50.82{\sim}51.20%$로 평균51.01%였다. 다중 정렬에 의해 염기서열을 비교한 결과 $99.7{\sim}100%$ 일치하여 종간에 차이가 적었다.

• 한국소음진동공학회논문집
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• 제12권4호
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• pp.280-286
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• 2002

It has been long suspected that the transition region may give rise to local pressure fluctuations and radiated sound that are different from those created by the fully-developed turbulent boundary layer at equivalent Reynolds number. Experimental investigation described in this paper concerns the characteristics of pressure fluctuations at the transition. Flush-mounted microphones and hot wires are used to measure the pressure fluctuations and local flow velocities within the boundary layer in the low noise wind tunnel. From this experiment we could observe the spatial and temporal development process of T-S wave using Wigner-Ville method and find the relations between the characteristic frequency of T-S wave and free stream velocity and the boundary layer thickness based on nondimensional pressure spectra scaled on outer variables.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.331-336
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• 1996

The effects of a mixing vane on air-water mixed flow have been experimentally studied in this work, to investigate the basic mechanisms that the mixing vane affects critical heat flux (CHF). Experiment was performed for various flow rates focusing on bubbly flow and annular flow patterns. Acrylic tube (1.7m long, 11 mm I.D.) and the split vane type mixing vane were used, and ring-type conductance probes were used to measure the liquid film thickness in annular flow. Experimental results show that, (a) bubbly-to slug flow transition and churn-to-annular flow transition occur respectively near the mixing vane compared to the tests without mixing vane, (b) in bubbly flow region, the mixing vane breaks the bubbles into smaller ones and forwards bubbles to the center region of the tube by the centrifugal force, (c) the liquid film thickness in annular flow is decreased near the mixing vane for mass fluxes.

• International Journal of Control, Automation, and Systems
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• 제2권3호
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• pp.354-361
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• 2004

To improve fault isolation performance of the Bayes isolator, this paper proposes the Fuzzy-Bayes isolator, which uses the Fuzzy-Bayes classifier as a fault isolator. The Fuzzy-Bayes classifier is composed of the Bayes classifier and weighting factor, which is determined by fuzzy inference logic. The Mahalanobis distance derivative is mapped to the weighting factor by fuzzy inference logic. The Fuzzy-Bayes fault isolator is designed for the BLDC motor fault diagnosis system. Fault isolation performance is evaluated by the experiments. The research results indicate that the Fuzzy-Bayes fault isolator improves fault isolation performance and that it can reduce the transition region chattering that is occurred when the fault is injected. In the experiment, chattering is reduced by about half that of the Bayes classifier's.