• Computers and Concrete
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• 제7권6호
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• pp.511-522
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• 2010

A color based segmentation procedure and a modified signature technique have been applied to the detection and analyses of complicated void shapes in cemented materials. The gray-scale segmentation and available signature methods were found to be inefficient especially for the analyses of complicated void shapes. The applicability of the developed methodology has been demonstrated on artificially prepared cemented materials made of self compacted concrete material. In order to characterize the void shapes in the investigated sample images, two new shape parameters called as coefficients of inclusion and exclusion have been proposed. When compared with the traditional use of the signature method, it was found that the methodology followed herein would better characterize complicated void shapes. The methodology followed in this study may be applied to the analysis of complicated void shapes that are often encountered in other cementitious materials such as clays and rocks.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.229-232
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• 2005

More than effectively judging the existence of voids behind concrete tunnel linings or under concrete pavements, this research aims to develop the analysis algorithm of radar capable of estimation of the shape of specific voids. To detect or estimate void shapes in non-reinforced concrete, the simulation analysis model of transmission and reflection wave of electromagnetic radar is used. This radar simulation model is carried out with various void shapes. As the results, a proposed method in this study has a possibility of detecting or estimating void shapes with good accuracy.

• 대한토목학회논문집
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• 제26권4A호
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• pp.809-816
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• 2006

다층경계를 갖는 콘크리트 내의 철근 위치와 공동(공극) 형상을 효과적으로 검출하기 위해, 본 연구에서는 다층경계를 갖는 철근 콘크리트의 레이더 응답 및 무근 콘크리트 내 공동의 형상추정이 가능한 전자파 레이더의 해석 알고리즘을 개발하는데 목표를 두고 있다. 이들 조건에서의 철근 및 공동형상을 검출 또는 추정하기 위해 레이더 모의해석 모델은 다양한 경계조건과 공동형상을 갖는 철근 또는 무근 콘크리트에 대해 적용되었다. 그리고 레이더 모의해석 결과에 대한 출력신호(화상)는 컨볼루션법에 의해 계산하여 나타내었다. 그 결과, 본 모의해석 기법은 철근콘크리트의 다층경계와 콘크리트의 공동형상에 대한 레이더 응답해석에 활용이 가능할 것으로 판단된다.

• 한국주거학회논문집
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• 제21권6호
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• pp.131-141
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• 2010

This study is aimed to grasp the spatial characteristics exhibited in the modern housing architecture from the aspect of a geometrical manipulation, which transforms basic geometrical shapes and persue the formative diversity, to identify and verify the various characteristics of spatial structure in modern housing architecture. In this regard, this paper analyze and identify the influences of the void spaces that are created by geometrical manipulations on housing architecture, in terms of morphological and environmental aspects. Theoretical approaches define the concept of geometrical manipulation according to the characteristics of residence and examine the spatial features of void spaces. Additionally, case studies result in the classification of void spaces that are created by geometrical manipulation. Furthermore, to understand environment-friendly characteristics of the void space, the researcher elicited the factors that can affect environment friendly housing from previous studies, and analyzed their correlation between those factors and the void spaces that are classified.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.721-727
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• 2000

Impedance method was carried out to design the electrode that can measure the void fraction of the bubbly flow in pool reservoir. To find out the optimum electrode shape, Styrofoam-tests were performed in a specially designed acrylic reservoir. Three kinds of electrodes were designed to compare the characteristics of water-air flow. The resistance was increased as the void fraction increased and the capacitance was decreased as the void fraction increased. The resistance is a main parameter to express the nature of the water-air flow in impedance method. Almost all the values of impedance were involved in resistance. The degree of deviation from the mean-resistance values showed reasonable results. Electrode type-I expressed excellent results among the three electrode shapes. The impedance values in void fraction 0-10% were similar to those of Maxwell's equation. But the impedance values in void fraction 10-20% were not similar to those of Maxwell' equation because of the edge effect near electrode.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.57-60
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• 2008

The studies for internal void closure have been conducted experimentally and numerically for open die forging. The FEM analysis is performed to investigate the deformation behavior of some internal voids in cast ingots during two upsetting stages. The calculated results of void closure behavior are compared with the measured results before and after upsetting. The shapes and sizes of each internal void are scanned by the X-ray scanner. From this result, the criteria for deformation amounts effect on the void closure can be investigated by the types of void. Closed voids could be compressed and eliminated after forging when the applied deformation amounts were larger than the critical effective strains. On the other hand, open voids could not be compressed and removed.

• 복식
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• 제57권2호
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• pp.155-171
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• 2007

Exaggerated expressions of contemporary fashion have exceeded historical precedents in volume. The purpose of this study is to understand the aesthetic characteristics of expanded form In contemporary fashion. To take dresses beyond their flat shapes into three-dimensional forms, it was investigated into volume of dresses by using the void and the mass. The void Is rarefied space and the mass is densified space. The void of dresses could be constructed from the boning such as panier and stiff textiles as organza lining. The mass could be constructed from padding. Fold, pleats, twist, and the layering of fabrics show features of both the void and the mass. Contemporary fashion designers relied on the void rather that the mass to make the enormous volume because of the weight of the mass. X-silhouette and the expansion of skirt and sleeve were dominant as the result of accentuating the body with a waistline. However, many of expanded dresses were so voluminous that they obscured the body's outlines. Some forms were strange and shocking. Many designers explored the void and there were a multitude of methods to construct the void: compartments of air, architectural techniques, technical textiles, fold such at origami. The aesthetic consciousness of expanded dresses could be classified into 7 categories, the giant, the dynamic, the deconstructive, the historical, the comedic, the rhythmical, and the technical character.

• 소성∙가공
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• 제16권2호
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• pp.126-131
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• 2007

Voids in a large rotor are formed in solidification process of a cast ingot. The voids have to be eliminated from the rotor by a forming process, because they would became stress-intensity factors which suddenly fracture the rotor in the operation. Previous studies on void-elimination of a large rotor have mainly focused on finding the process variables affecting the void-closure. But the study on the amount of void closure in a large rotor has been very rare. This study was performed to obtain an equation which predicts the amount of void-closure in a forging process of a large rotor and to evaluate the availability of the void-closure equation through finite element analyses. Firstly, 2D FE analysis was carried out to find effects of time integral of hydrostatic stress and effective strain on void volume rate of a large rotor in the upsetting process for various diameters and shapes of void, and material temperature. From the 2D FE analysis, we found that effective strain was suitable for predicting the void-closure of a large rotor, because there was a constant relationship between void volume rate and effective strain. And a void-closure equation was proposed fur predicting void-closure of a large rotor in the upsetting process. Finally, ken the 3D FE analysis, the proposed void-closure equation was verified to be useful for upsetting and cogging processes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.819-823
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• 1996

In the large steel ingosts, void defects exhibiting microvoid shapes are inevitably formed in the V-segregation zone of the ingots during solidification. In the hot open-die forging process, material properties are improved by eliminating internal porosity. The void size is practically very small as compared with the huge large ingot. Thus, for deformation analysis of a large ingot, a massive number of elements are needed in order to describe a void surface and to uniform mesh sturcture. In the present work the Global/Local scheme has been introduced in order to reduce the computational time and to easily generate the mesh system as a void module of local mesh for obtaining the accurate solution around a void. The procedure of the global- local method consists of two steps. In the first step global analysis is carried out which seeks a reasonably good solution with a cpurse mesh system without describing a void. Then, a local analysis is performed locally with a fine mesh system under the size-criterion of a local region. The computational time has been greatly reduced. Though the work it has been shown that large ingot forging incorporation small voids can be effectively analyzed by using the proposed Global/Local scheme.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.231-234
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• 2000

The corona in oil, the surface discharge in oil, the void discharge which could be in a transformer were imitated by using three electrodes with different shapes and the frequency bands of each ultrasonic signal were measured. After emitting artificial noises toward the transformer, only ultrasonic signals were extracted by frequency filtering, from the ultrasonic signals with noises at partial discharge. As a result, it was confirmed that the ultrasonic signals due to the corona in oil, the surface discharge in oil, the void discharge could be distinguished from the noises.