• 제목/요약/키워드: Component school

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항공기 낙뢰 시험을 위한 Component A 축소 파형 도식화 방법 (A Method of Plotting Component A Scaled Waveform for Aircraft Lightning Test)

  • 조재현;김윤곤;김동현;이학진;명노신
    • 한국항공우주학회지
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    • 제49권9호
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    • pp.801-811
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    • 2021
  • 낙뢰는 짧은 시간 동안 다량의 에너지를 항공기에 전달하여 치명적인 결과를 초래할 수 있다. 특히 낙뢰는 고온의 열과 전류를 동반하여 항공기 표면 손상과 내부 전자장비에 영향을 미쳐 비행의 안전에 심각한 영향을 미칠 수 있다. 이를 분석하기 위한 낙뢰 시험에는 미항공우주원고서 SAE ARP 5412B에 규정된 최대전류 200kA인 Component A 파형이 사용된다. 하지만 실제 낙뢰 크기는 대부분 35kA 내외로 발생하며 전기체 대상으로 하는 낙뢰 간접 시험에서 내부 전자장비 손상 예방을 위해 파형을 축소하여 시험을 진행한다. 본 연구에서는 기존 Component A 축소 파형을 도식화하는 방법을 알아보고 그 한계를 분석하였다. 나아가 항공기 낙뢰 Component A 파형의 보정계수를 조절하는 방식의 신규 축소 파형 도식 방법을 제안한다. 마지막으로 전자기 해석 소프트웨어 EMA3D를 활용하여 EC-155B 헬리콥터 내부 케이블 하네스의 파형 감소비에 따른 내부 유도 전류 크기 감소비를 비교하였다.

Strain hardening behavior of linear polymer melts

  • Hong Joung Sook;Ahn Kyung Hyun;Lee Seung Jong
    • Korea-Australia Rheology Journal
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    • 제16권4호
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    • pp.213-218
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    • 2004
  • Linear high-density polyethylene (PE) was controlled to induce strain-hardening behavior by introducing a small amount of second component with an anisotropic structure. In order to form an anisotropic structure in the PE matrix, the polymer was extruded through a twin-screw extruder, and the structure was controlled by varying the extrusion conditions. Depending on conditions, the second component formed a film, thread and droplet structure. If the second component was kept rigid, the morphology evolution could be delayed and the second component could maintain its film or thread structure without further relaxation. In par­ticular, the second component of the thread structure made a physical network and gave rise to remarkable strain hardening behavior under high extension. This study suggests a new method that induces strain hard­ening behavior by introducing a physically networked second component into the linear polymer melt. This result is anticipated to improve the processibility of linear polymers especially when extensional flow is dominant, and to contribute to our understanding of strain hardening behavior.

Multi-level Scheduling Algorithm Based on Storm

  • Wang, Jie;Hang, Siguang;Liu, Jiwei;Chen, Weihao;Hou, Gang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제10권3호
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    • pp.1091-1110
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    • 2016
  • Hybrid deployment under current cloud data centers is a combination of online and offline services, which improves the utilization of the cluster resources. However, the performance of the cluster is often affected by the online services in the hybrid deployment environment. To improve the response time of online service (e.g. search engine), an effective scheduling algorithm based on Storm is proposed. At the component level, the algorithm dispatches the component with more influence to the optimal performance node. Inside the component, a reasonable resource allocation strategy is used. By searching the compressed index first and then filtering the complete index, the execution speed of the component is improved with similar accuracy. Experiments show that our algorithm can guarantee search accuracy of 95.94%, while increasing the response speed by 68.03%.

Mechanical behavior investigation of steel connections using a modified component method

  • Chen, Shizhe;Pan, Jianrong;Yuan, Hui;Xie, Zhuangning;Wang, Zhan;Dong, Xian
    • Steel and Composite Structures
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    • 제25권1호
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    • pp.117-126
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    • 2017
  • The component method is an analytical approach for investigating the moment-rotation relationship of steel connections. In this study, the component method was improved from two aspects: (i) load analysis of mechanical model; and (ii) combination of spring elements. An optimized component method with more reasonable component models, spring arrangement position, and boundary conditions was developed using finite element analysis. An experimental testing program in two major-axis and two minor-axis connections under symmetrically loading was carried out to verify this method. The initial rotational stiffness obtained from the optimized component method was consistent with the experimental results. It can be concluded that (i) The coupling stiffness between column and beam flanges significantly affects the effective height of the tensile-column web. (ii) The mechanical properties of the bending components were obtained using an equivalent t-stub model considering the bending capacity of bolts. (iii) Using the optimized mechanical components, the initial rotational stiffness was accurately calculated using the spring system. (iv) The characteristics of moment-rotation relationship for beam to column connections were effectively expressed by the SPRING element analysis model using ABAQUS. The calculations are simpler, and the results are accurate.

A Noisy Infrared and Visible Light Image Fusion Algorithm

  • Shen, Yu;Xiang, Keyun;Chen, Xiaopeng;Liu, Cheng
    • Journal of Information Processing Systems
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    • 제17권5호
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    • pp.1004-1019
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    • 2021
  • To solve the problems of the low image contrast, fuzzy edge details and edge details missing in noisy image fusion, this study proposes a noisy infrared and visible light image fusion algorithm based on non-subsample contourlet transform (NSCT) and an improved bilateral filter, which uses NSCT to decompose an image into a low-frequency component and high-frequency component. High-frequency noise and edge information are mainly distributed in the high-frequency component, and the improved bilateral filtering method is used to process the high-frequency component of two images, filtering the noise of the images and calculating the image detail of the infrared image's high-frequency component. It can extract the edge details of the infrared image and visible image as much as possible by superimposing the high-frequency component of infrared image and visible image. At the same time, edge information is enhanced and the visual effect is clearer. For the fusion rule of low-frequency coefficient, the local area standard variance coefficient method is adopted. At last, we decompose the high- and low-frequency coefficient to obtain the fusion image according to the inverse transformation of NSCT. The fusion results show that the edge, contour, texture and other details are maintained and enhanced while the noise is filtered, and the fusion image with a clear edge is obtained. The algorithm could better filter noise and obtain clear fused images in noisy infrared and visible light image fusion.

Development of reutilization system for Nuclear Power Plant Component using Object-Oriented Systems Engineering Method

  • Yeo, Tae Ho;Kim, Tae Ryong;Kim, Chang Lak
    • 시스템엔지니어링학술지
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    • 제12권2호
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    • pp.69-80
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    • 2016
  • The purpose of this study is to establish a component reutilization system in Nuclear Power Plant (NPP) by Object-Oriented Systems Engineering Method (OOSEM). Unified Modeling Language (UML) is mainly used for OOSEM. Operational Concept (OpsCon), Use cases, Structure Diagrams, and Behavior Diagrams are developed to analyze stakeholders needs, system requirements, logical architecture, and physical architecture. Based on the current decommissioning and purchasing system of the component, some activities from their systems were excepted and additional new activities were developed for a component reutilization system.

Automatic Defect Detection from SEM Images of Wafers using Component Tree

  • Kim, Sunghyon;Oh, Il-seok
    • JSTS:Journal of Semiconductor Technology and Science
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    • 제17권1호
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    • pp.86-93
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    • 2017
  • In this paper, we propose a novel defect detection method using component tree representations of scanning electron microscopy (SEM) images. The component tree contains rich information about the topological structure of images such as the stiffness of intensity changes, area, and volume of the lobes. This information can be used effectively in detecting suspicious defect areas. A quasi-linear algorithm is available for constructing the component tree and computing these attributes. In this paper, we modify the original component tree algorithm to be suitable for our defect detection application. First, we exclude pixels that are near the ground level during the initial stage of component tree construction. Next, we detect significant lobes based on multiple attributes and edge information. Our experiments performed with actual SEM wafer images show promising results. For a $1000{\times}1000$ image, the proposed algorithm performed the whole process in 1.36 seconds.

주성분 분석기법을 이용한 심전도 기반 개인인증 (ECG based Personal Authentication using Principal Component Analysis)

  • 조주희;조병준;이대종;전명근
    • 전기학회논문지P
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    • 제66권4호
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    • pp.258-262
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    • 2017
  • The PCA(Principal Component Analysis) algorithm is widely used as a technique of expressing the eigenvectors of the covariance matrix that best represents the characteristics of the data and reducing the high dimensional vector to a low dimensional vector. In this paper, we have developed a personal authentication method based on ECG using principal component analysis. The proposed method showed excellent recognition performance of 98.2 [%] when it was experimented using electrocardiogram data obtained at weekly intervals. Therefore, it can be seen that it is useful for personal authentication by reducing the dimension without changing the information on the variability and the correlation set variable existing in the electrocardiogram data by using the principal component analysis technique.

독립성분 분석기법에 의한 심전도 신호의 왜곡 보정 (Suppressing Artefacts in the ECG by Independent Component Analysis)

  • 김정환;김경섭;김현태;이정환
    • 전기학회논문지
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    • 제62권6호
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    • pp.825-832
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    • 2013
  • In this study, Independent Component Analysis (ICA) algorithms are suggested to extract the original ECG part from the mixed signal contaminated with the unwanted frequency components and especially 60Hz power line disturbances. With this aim, we implement a novel method to suppress the baseline-wandering disturbances and power line artefacts contained in patch-electrodes sensory ECG data by separating the unmixed signal with finding the optimal weight W based on Kurtosis value. With applying brutal force and gradient ascent searching algorithm to find W, we can conclude that the unwanted frequency components especially in the ambulatory ECG data can be eliminated by Independent Component Analysis.

Meningiomas with Rhabdoid or Papillary Components : Prognosis and Comparison with Anaplastic Meningiomas

  • Kim, Jeong-Kwon;Jung, Tae-Young;Jung, Shin;Lee, Kyung-Hwa;Kim, Seul-Kee;Lee, Eun Jung
    • Journal of Korean Neurosurgical Society
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    • 제59권4호
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    • pp.357-362
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    • 2016
  • Papillary and rhabdoid meningiomas are pathologically World Health Organization (WHO) grade III. Any correlation between clinical prognosis and pathologic component is not clear. We analyzed the prognoses of patients with meningiomas with a rhabdoid or papillary component compared to those of patients with anaplastic meningiomas. From 1994 to June 2013, 14 anaplastic meningiomas, 6 meningiomas with a rhabdoid component, and 5 meningiomas with papillary component were pathologically diagnosed. We analyzed magnetic resonance imaging (MRI) findings, extent of removal, adjuvant treatment, progression-free survival (PFS), overall survival (OS), and pathologic features of 14 anaplastic meningiomas (group A), 5 meningiomas with a predominant (${\geq}50%$) papillary or rhabdoid component (group B1), and 6 meningiomas without a predominant (<50%) rhabdoid or papillary component (group B2). Homogeneous enhancement on MRI was associated with improved PFS compared to heterogeneous enhancement (p=0.025). Depending on pathology, the mean PFS was $134.9{\pm}31.6\;months$ for group A, $46.6{\pm}13.4\;months$ for group B1, and $118.7{\pm}19.2\;months$ for group B2. The mean OS was $138.5{\pm}24.6\;months$ for group A and $59.7{\pm}16.8\;months$ for group B1. All recurrent tumors were of the previously diagnosed pathology, except for one tumor from group B1, which recurred as an atypical meningioma without a papillary component. Group B1 tumors showed a more aggressive behavior than group B2 tumors. In group B2 cases, the pathologic findings of non-rhabdoid/papillary portion could be considered for further adjuvant treatment.