• Journal of Advanced Marine Engineering and Technology
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• v.20 no.4
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• pp.90-100
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• 1996

To maintain high spacial accuracy and rapid CPU time in interpolating data from grid to random position or inversely in PIV, proposed many technuques are compared and discussed mainly in terms of interpolating error and computing time. And artificial PIV atmosphere data is furnished by CFD result. First, for interpolation from grid to random position, multiquadric method gives the highest accuracy with the longest CPU time and Taylor series expansion methods give reasonable accuracy with less calculating load. Secondly, the sub-pixel resolution analysis in estimating the coordinates of the maximum correlation coefficients essential in the grey level correlation PIV reveal that 8-neighbours 2nd-order least square interpolation gives utmost accuracy in terms of the real flow conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.4
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• pp.412-412
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• 1996

To maintain high spacial accuracy and rapid CPU time in interpolating data from grid to random position or inversely in PIV, proposed many technuques are compared and discussed mainly in terms of interpolating error and computing time. And artificial PIV atmosphere data is furnished by CFD result. First, for interpolation from grid to random position, multiquadric method gives the highest accuracy with the longest CPU time and Taylor series expansion methods give reasonable accuracy with less calculating load. Secondly, the sub-pixel resolution analysis in estimating the coordinates of the maximum correlation coefficients essential in the grey level correlation PIV reveal that 8-neighbours 2nd-order least square interpolation gives utmost accuracy in terms of the real flow conditions.

• Korean Journal of Remote Sensing
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• v.4 no.1
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• pp.17-29
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• 1988

본 연구에서는 지면의 표적물 및 하늘과 구름애서 산라되어 나오는 방향성 복사량을 효 율적으로 측정하고, 이들 산란광에 의한 Remote Sensing(원격탐사) 자료해석상의 영향을 조사 연 구하기 위해 만들어진 나선형식으로 회전하며 거의 전반구를 11초 이내에 주사하는 Sphere-Scanning Radiometer의 자료를 분석하는 데 필요한 software(S/W)들을 개발하였다. 개발 된 S/W 에는 개개의 측정자료가 기록될 순간에 측정기의 Field of View (FOV)에 의해 실제로 산란광이 집적된 지표면상의 부분을 시각적으로 나타내 주고 복사강도를 Grey Level로 나타낼 수 있는 도면표시 Algorithm과 FOV각의 크기에 따라 overlap부분의 면적을 계산하는 Algorithm 등이 포함되어 있다. 또한, 실험농장에서 본 radiometer로 측정한 자료를 이 S/W를 사용하여 분 석해 본 결과 밝혀진 몇 가지 방향성 복사량의 특성들을 간단히 소개 하였다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.12
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• pp.1154-1160
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• 2005

A panoramic-PIV system has been constructed for the analysis of the airflows in a room. Smoke is used as seeding particles and are visualized by a pulsed laser (Nd-Yag, 120 mJ). Panoramic images have been obtained by an image composition process using the two images obtained by the two cameras $(1k\times1k)$ that are viewing the wide measurement areas. Velocity vector fields have been obtained by the grey-level cross-correlation PIV method. Three room models $(L{\times}W{\times}H[mm^3],\;500\times500\times250,\;350\times350\times175,\;250\times250\times125)$ have been tested. The experimental results have proven that the constructed panoramic-PIV system can be used as a useful tool for analyzing the airflow characteristics in the room models.

• Structural Engineering and Mechanics
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• v.76 no.2
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• pp.193-205
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• 2020

The growing need for assuring efficient and sustainable investments in civil engineering structures has determined a renovated interest in the rational design of such structures from designers, clients and authorities. As a result, risk-informed decision-making methodologies are increasingly being used as a direct decision tool or as an upper-level layer from which performance-based approaches are then calibrated against. One of the most important and challenging aspects of today's structural design is to adequately handle the system-level effects, the known unknowns and the unknown unknowns. These aspects revolve around assessing and evaluating relevant damage scenarios, namely those involving unacceptable/intolerable damage levels. Hence, the importance of risk analysis of disproportionate collapse, and along with it of robustness. However, the way robustness has been used in modern design codes varies substantially, from simple provisions of prescriptive rules to complex risk analysis of the disproportionate collapse. As a result, implementing design for robustness is still very much a grey area and more so when it comes to defining means to quantify robustness. This paper revisits the most common robustness frameworks, highlighting their merits and limitations, and identifies one among them which is very promising as a way forward to solve the still open challenges.

• The Transactions of the Korea Information Processing Society
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• v.7 no.11
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• pp.3592-3602
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• 2000

Image processing consist of image analysis and classification. The one is extracting of feature value in the image. The other is segimentationof image that have same properiv. A novel approach for the analysis and classification of tezture images based on statistical texture prunitive estraction are proposed. In this approach, feature vector extracting is based on stalisucal method using apatial dependence of grey level and use general lexture proerty. In is advantageous that not effiected on structure and type of lexture. These components describe the amount of roughness and softness of texture images Two leatures. Moment and Homogeneity, are componted from GLCM(gray level co-occurrence matrices) of the lexture promitive to charactenize statisical properties of the image. We show the successful experimental results by considerationof these two components fro the analysis and classificationto regular and irregular texture images.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.4
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• pp.437-442
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• 1997

An experimental study was carried out in a channel cavity with square heat surface by visual¬ization equipment with Mach - Zehnder interferometer and laser apparatus. The image processing system consists of one commercial image board slit into a personal computer and 2-dimensional sheet light by Argon-Ion Laser with cylindrical lens and flow picture recording system. Instant simultaneous velocity vectors at whole field were measured by 2-D PIV system which adopted two¬frame grey-level cross correlation algorithm. Heat source was uniform heat flux(o.4W/cm$^2$, , O.8W/cm$^2$, 1.2W/cm$^2$). Obtained result showed various flow patterns such as kinetic energy distribution. Severe unsteady flow fluctuation within the cavity are remarkable and sheared mixing layer phenomena are also found at the region where inlet flow is collided with the counter-clockwise rotating main primary vortex. Photographs of Mach ~ Zehnder are also compared in terms of constant heat flux.

• Journal of Welding and Joining
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• v.32 no.2
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• pp.54-62
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• 2014

Manhole cover, which is usually made of grey cast iron and consists of frame and cover, should have enough strength to support the heavy traffic load. The manhole cover made of cast iron has heavy weight to handle manually and is vulnerable to impact force with its brittle characteristics. Moreover, its production process of casting has been regulated in terms of environmental pollution. In this study, steel manhole cover is proposed to substitute the cast cover with a series of structural analyses to confirm its strength to support the test load for manhole cover. The cover of the proposed steel manhole cover is made of thin circular pate and stiffeners below the plate. Rectangular columns and hollow circular plate were selected for the shape of the stiffener. In order to give enough strength for the cover to behave within elastic range in the loading, strengthening structures of the cover were varied with increasing the number and the size of the stiffeners. The results of the analyses revealed that when both the hollow circular stiffener and cross stiffeners were additionally applied at the same time to the steel cover with longitudinal stiffeners, the maximum stress level in the cover could be reduced to that level presented in the cast cover.

• Journal of Magnetics
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• v.22 no.1
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• pp.34-42
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• 2017

Material defects in the Steam Generator Tubes (SGT) of sodium cooled fast breeder reactor (PFBR) can lead to leakage of water into sodium. The water and sodium reaction will lead to major accidents. Therefore, the examination of steam generator tubes for the early detection of defects is an important requirement for safety and economic considerations. In this work, the Magnetic Flux Leakage (MFL) based Non Destructive Testing (NDT) technique is used to perform the defect detection process. The rectangular notch defects on the outer surface of steam generator tubes are modeled using COMSOL multiphysics 4.3a software. The obtained MFL images are de-noised to improve the integrity of flaw related information. Grey Level Co-occurrence Matrix (GLCM) features are extracted from MFL images and taken as input parameter to train the neural network. A comparative study on characterization have been carried out using feed-forward back propagation (FFBP) and cascade-forward back propagation (CFBP) algorithms. The results of both algorithms are evaluated with Mean Square Error (MSE) as a prediction performance measure. The average percentage error for length, depth and width are also computed. The result shows that the feed-forward back propagation network model performs better in characterizing the defects.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.687-690
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• 2017

Edge detection is an important step in determining the performance of lane recognition, object and pattern detection, and so on. And much research has been done until now. Sobel, Prewitt, Roberts, and Canny edge detection algorithms are widely known. However, these algorithms are often judged to be a non-edge region when processing a smooth change in brightness value. Therefore, in this paper, edge detection algorithm using gray-level morphology using erosion, expansion, open and close in the mask area. is proposed.