• Title/Summary/Keyword: 비등 곡선

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직교이방성 판 내에서의 균열전파 해석

  • 김만원;박재학
    • Proceedings of the Korean Institute of Industrial Safety Conference
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    • 2000.11a
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    • pp.251-256
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    • 2000
  • 이방성 재료에서 균열의 성장을 예측하는 것은 실제 구조물의 안전성을 정확하게 해석하기 위한 중요한 문제이다. 이방성 재료 내에서의 균열의 거동은 등방성 재료의 경우와는 다르기 때문에 이방성 재료 내의 균열 해석 문제가 중요한 관심을 끌게 되었다. 비등방성 재료에 대한 지금까지의 연구는 대부분 직선균열의 해석, 직선균열의 초기 전파 각도에 대한 해석에 대하여 이루어져 왔고 곡선 균열에 대한 연구[1-4]는 많이 이루어지지 않았다.(중략)

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A Study on the Heat Transfer of Carbon Steels in Quenching (탄소강의 담금질 열전달에 관한 연구)

  • 김경근;윤석훈
    • Journal of Advanced Marine Engineering and Technology
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    • v.19 no.2
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    • pp.20-26
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    • 1995
  • The very rapid cooling problem from $820^{\circ}$C to $20^{\circ}$C on the surface of the steel by thermal conduction including the latent heat of phase transformation of steel and by transient boiling heat transfer of water are considered to principal problem in quenching. The transient boiling process of water at the surface of specimen during the quenching process were experimentally analyzed. Then the heat flux was numerically calculated by the numerical method of inverse heat condition problem. In this report, the simulation program to calculate the cooling curves for large rolls was made using the subcooled transient boiling curve as a boundary condition. By this simulation program, the cooling curves of rolls from D=50mm to D=200mm were calculated and the effects of agitation of circulation of water also investigated.

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Analysis of Anisotropic Circular Conical Shells with Free Supports (자유경계를 갖는 비등방성 원뿔형 쉘의 해석)

  • Son, Byung Jik;Baik, Han Sol;Chang, Suk Yoon
    • Journal of Korean Society of Steel Construction
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    • v.12 no.4 s.47
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    • pp.417-428
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    • 2000
  • In recent years, composite materials have been used in civil engineering as well as architecture, automobile, aerospace, shipping industries. Composite materials are composed of two or more different materials to produce desirable properties for structural strength. The shell structures have the advantage of more efficient load resistance due to its curved shape as compared to the plate structures. And the shell structures with composite materials have many advantages in strength, corrosion resistance, and weight reduction. The objective of this study is to analyze circular conical shells with shear deformation effects and to prove the advantage of composite materials. To solve differential equations of conical shells, this paper used finite difference method.

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A Study on the Coolingability of Several Quenchants(I) - Coolingability of Selected Aqueous Solution- (각종 담금제의 냉각성능에 관한 연구 I -물을 주성분으로 한 담금제의 냉각성능 평가-)

  • 민수홍;구본권;김상열
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.3
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    • pp.411-418
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    • 1989
  • Quenching effect depends upon coolingability of quenchant as well as the composition of steel. Study on the coolingability of quenchants is important in cooling process and heat treatment of steel. Experimental apparatus and measuring method follow Korean Industrial Standard. Distilled water, different concentration of NaCl, NaOH and Na$_{2}$CO$_{3}$ solutions were compared. Also the effect of temperature of distilled water were calculated. Experimental results were examined with F.E.M. analysis.

A Novel Range-Free Localization Algorithm for Anisotropic Networks to enhance the Localization Accuracy (비등방성 네트워크에서 위치 추정의 정확도를 높이기 위한 향상된 Range-Free 위치 인식 기법)

  • Woo, Hyun-Jae;Lee, Chae-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.7B
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    • pp.595-605
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    • 2012
  • DV-Hop is one of the well known range-free localization algorithms. The algorithm works well in case of isotropic network since the sensor and anchor nodes are placed in the entire area. However, it results in large errors in case of anisotropic networks where the hop count between nodes is not linearly proportional to the Euclidean distance between them. Hence, we proposed a novel range-free algorithm for anisotropic networks to improve the localization accuracy. In the paper, the Euclidean distance between anchor node and unknown node is estimated by the average hop distance calculated at each hop count with hop count and distance information between anchor nodes. By estimating the unknown location of nodes with the estimated distance estimated by the average hop distance calculated at each hop, the localization accuracy is improved. Simulation results show that the proposed algorithm has more accuracy than DV-Hop.

Video Segmentation using the Level Set Method (Level Set 방법을 이용한 영상분할 알고리즘)

  • 김대희;호요성
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.40 no.5
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    • pp.303-311
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    • 2003
  • Since the MPEG-4 visual standard enables content-based functionalities, it is necessary to extract video object from natural video sequences. Segmentation algorithms can largely be classified into automatic segmentation and user-assisted segmentation. In this paper, we propose a user-assisted VOP generation method based on the geometric active contour. Since the geometric active contour, unlike the parametric active contour, employs the level set method to evolve the curve, we can draw the initial curve independent of the shape of the object. In order to generate the edge function from a smoothed image, we propose a vector-valued diffusion process in the LUV color space. We also present a discrete 3-D diffusion model for easy implementation. By combining the curve shrinkage in the vector field space with the curve expansion in the empty vector space, we can make accurate extraction of visual objects from video sequences.

Improved Shape Extraction Using Inward and Outward Curve Evolution (양방향 곡선 전개를 이용한 개선된 형태 추출)

  • Kim Ha-Hyoung;Kim Seong-Kon;Kim Doo-Young
    • Journal of the Institute of Convergence Signal Processing
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    • v.1 no.1
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    • pp.23-31
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    • 2000
  • Iterative curve evolution techniques are powerful methods for image segmentation. Classical methods proposed curve evolutions which guarantee close contours at convergence and, combined with the level set method, they easily handled curve topology changes. In this paper, we present a new geometric active contour model based on level set methods introduced by Osher & Sethian for detection of object boundaries or shape and we adopt anisotropic diffusion filtering method for removing noise from original image. Classical methods allow only one-way curve evolutions : shrinking or expanding of the curve. Thus, the initial curve must encircle all the objects to be segmented or several curves must be used, each one totally inside one object. But our method allows a two-way curve evolution : parts of the curve evolve in the outward direction while others evolve in the inward direction. It offers much more freedom in the initial curve position than with a classical geodesic search method. Our algorithm performs accurate and precise segmentations from noisy images with complex objects(jncluding sharp angles, deep concavities or holes), Besides it easily handled curve topology changes. In order to minimize the processing time, we use the narrow band method which allows us to perform calculations in the neighborhood of the contour and not in the whole image.

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Strength and Deformation Behavior of Steel Plates under Cyclic Loadinga (반복하중을 받는 강판의 강도 및 변형특성)

  • Hwang, Won-Sup;Yoon, Hyung-Suk;Jeon, Seung-Kwon
    • Journal of Korean Society of Steel Construction
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    • v.13 no.2
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    • pp.143-152
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    • 2001
  • This paper presents are monotonic and cyclic behavior of steel plates. The effects of design parameters, initial deflection and aspect ratio, width-thickness ratio are studied by using FEM analysis. The results obtained from the monotonic loadings show that the aspect ratio(a/b) on the strength is to be neglected in the range of $(a/b){\leq}1.0$. The major cause of the reduction in strength sbbjected to cyclic loadings are width-thickness ratio and displacement amplitude. Based on the results, this paper presents some new strength curve with considering the cyclic deteriorations. The results are also discussed about the deformation capacity accordance with the width-thickness ratio and displacement amplitude.

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Detection of the Optic Disk Boundary in Retinal Images using Image inpainting based on PDE (PDE 기반의 이미지 인페인팅을 이용한 시신경 원판 경계 검출에 관한 연구)

  • Kim, Tae-Hyoung;Kim, Seng-Hyen;Kim, Jin-Man;Gong, Jae-Woong;Kim, Doo-Young
    • Journal of the Institute of Convergence Signal Processing
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    • v.8 no.4
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    • pp.249-254
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    • 2007
  • This paper describes a technique for detecting the boundary of the optic disk in digital image of the retina using inward and outward curve evolution. Optic disk boundary offers medical information about glaucoma progresses. For accurate boundary detection, image inpainting based on PDE removes blood vessels crossing the optic disk. For removing noises and preserving boundary of optic disk in image inpainting process, the anisotropic diffusion filtering is developed. After pre-processing, the optic disk boundary is determined using inward and outward curve evolution. Experimental results show that blurring effect of original region and optic disk boundary is reduced considerably. By the proposed method, we can detect correct disk boundary compare to conventional method.

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Study on Correlation of Critical Heat Flux in Spray Cooling (분무냉각에 있어서 임계열유속 상관식에 관한 연구)

  • Kim, Yeung Chan
    • Journal of ILASS-Korea
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    • v.23 no.3
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    • pp.109-113
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    • 2018
  • The critical heat flux of spray cooling were measured on the test surface of 10 mm diameter made by stainless steel. The experiments were carried out for the droplet-flow-rate of $0.00002{\sim}0.003m^3/(m^2s)$ and liquid subcooling temperature of $40{\sim}75^{\circ}C$. Experimental results showed that the critical heat flux of spray cooling increased remarkably with the increase of droplet-flow-rate. Meanwhile, the effect of liquid subcooling on critical heat flux of spray cooling appeared weakly under the present experimental conditions. In additions, correlation between the dimensionless critical heat flux and Weber number based on droplet-floe-rate was developed for experimental results.