• Structural Engineering and Mechanics
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• 제51권1호
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• pp.181-197
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• 2014

Stress determination is a very important step in the assessment of the safety of existing reinforced concrete structures. In rock mechanic this goal is achieved with the over-coring technique. The main idea behind such a technique is to isolate a material sample from the stress field in the surrounding mass and monitor its re-equilibrium deformation response. If the materials remains elastic, and elastic properties are known, stresses may be obtained from the corresponding measured strains. The goal of this paper is to evaluate if the over-coring technique is applicable to reinforced concrete members. The results of an experimental investigation on the behaviour of compressed concrete columns subjected to the over-coring technique are presented. Considerations about the range of applicability of the technique are made by comparing the measured and the theoretical stresses. After that, results of failure tests on drilled specimens are presented and discussed. Furthermore, the response is compared with that of columns core-bored before the compressive test. Finally, comparisons with numerical analysis are shown.

• The Journal of Advanced Prosthodontics
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• 제7권3호
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• pp.233-239
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• 2015

PURPOSE. This study aimed to evaluate the fit of zirconia ceramics before and after veneering, using 3 different veneering processes (layering, press-over, and CAD-on techniques). MATERIALS AND METHODS. Thirty standardized zirconia CAD/CAM frameworks were constructed and divided into three groups of 10 each. The first group was veneered using the traditional layering technique. Press-over and CAD-on techniques were used to veneer second and third groups. The marginal gap of specimens was measured before and after veneering process at 18 sites on the master die using a digital microscope. Paired t-test was used to evaluate mean marginal gap changes. One-way ANOVA and post hoc tests were also employed for comparison among 3 groups (${\alpha}$=.05). RESULTS. Marginal gap of 3 groups was increased after porcelain veneering. The mean marginal gap values after veneering in the layering group ($63.06{\mu}m$) was higher than press-over ($50.64{\mu}m$) and CAD-on ($51.50{\mu}m$) veneered groups (P<.001). CONCLUSION. Three veneering methods altered the marginal fit of zirconia copings. Conventional layering technique increased the marginal gap of zirconia framework more than pressing and CADon techniques. All ceramic crowns made through three different veneering methods revealed clinically acceptable marginal fit.

• 한국의류학회지
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• 제30권4호
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• pp.507-518
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• 2006

This study aims to prove that traditional patchwork wrapping cloth can be a creative motive for modem fashion, and the application of it can be a way of expressing not only the pride in our cultural heritage but also the originality of fashion design. The analysis of the plasticity of 108 patchwork wrapping clothes has come up with the following findings: Firstly, the plane structure consists of 41 basic forms and 67 applied ones. Secondly, 61 contrast color harmony and 47 similarity color harmony. Thirdly, the fabric consists of 88 silk clothes, 19 ramie clothes, and 1 silk and ramie cloth. Fourthly, 47 unlined clothes and 61 lined ones. The study also expresses the analyzed plasticity of patchwork wrapping cloth for fashion with the following findings: Firstly, basic plane structures, contrast color harmony, silk cloth and the press flower coating technique become one piece dress to express splendid and elegant image. Secondly, application plane structures, similarity color harmony of natural dyeing method using persimmon, ramie cloth and the press flower coating and over lock technique become a jacket and a blouse to express calm and dynamic image. Thirdly, the needling and over lock technique used to patch clothes has become a desirable way to express fabric with unique surface effects. Fourthly, the press flower coating which modernizes embroidery in patchwork wrapping. cloth has become a new technique which can create high values with its extended the visual effects of the material. Fifthly, Patchwork wrapping cloth in Chosun Dynasty has now become a motive for modem fashion design to express tradition and creation.

• 한국산학기술학회논문지
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• 제13권12호
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• pp.5931-5936
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• 2012

3.0T 고자기장 자기공명분광법에서 비알콜성 지방간 환자 평가를 위해 PRESS 기법과 Biopsy결과의 상관관계를 토대로 PRESS 기법의 임상적 유용성을 알아보았다. 본 실험은 3.0T 고자지장 자기공명영상 장비를 이용하여 실험을 하였고 분광스펙트럼을 적분(peak area integration) 방법으로 면적을 구하여 간지방량에 상대비율에 따른 공명피크의 면적을 이용하여 계산하였다. 비알콜성 지방간환자에서 MR 스펙트럼 피크가 모두 0.9 - 1.6 ppm에서 나타났으며 비알콜성 환자에 대하여 MRS와 Biopsy 결과 민감도 94%와 특이도 80%로 높은 값을 얻었다(p=0.000). 정상(r=0.79, p=0.04) 및 비알콜성 지방간질환 대한 결과( r=0.89, p=0.002) 역시 높은 상관관계를 보여주었다. 따라서 3.0T 고자장 MRS을 적용했을 때 PRESS 기법은 비알콜성 지방간 환자를 평가하는데 있어서 정상부분과 지방간부분의 구별을 가능하게 하였으며 생검검사와 MRS의 상관관계 분석에서 간지방량 비율(%)은 r값이 0.7 이상의 높은 Lipid를 제공하여 PRESS 기법의 임상적 유용성을 권고 할 만하였다.

• Structural Engineering and Mechanics
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• 제28권4호
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• pp.461-477
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• 2008

An adaptive finite element method for analyzing two-dimensional and axisymmetric nonlinear elastic fracture mechanics problems with cracks is presented. The J-integral is used as a parameter to characterize the severity of stresses and deformation near crack tips. The domain integral technique, for which all relevant quantities are integrated over any arbitrary element areas around the crack tips, is utilized as the J-integral solution scheme with 9-node degenerated crack tip elements. The solution accuracy is further improved by incorporating an error estimation procedure onto a remeshing algorithm with a solution mapping scheme to resume the analysis at a particular load level after the adaptive remeshing technique has been applied. Several benchmark problems are analyzed to evaluate the efficiency of the combined domain integral technique and the adaptive finite element method.

• Coupled systems mechanics
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• 제9권6호
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• pp.521-538
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• 2020

The present study is concerned with the thermoelastic interactions in a two dimensional homogeneous, transversely isotropic thermoelastic solid with new modified couple stress theory without energy dissipation and with two temperatures in frequency domain. The time harmonic sources and Hankel transform technique have been employed to find the general solution to the field equations.Concentrated normal force, normal force over the circular region, thermal point source and thermal source over the circular region have been taken to illustrate the application of the approach. The components of displacements, stress, couple stress and conductive temperature distribution are obtained in the transformed domain. The resulting quantities are obtained in the physical domain by using numerical inversion technique. Numerically simulated results are depicted graphically to show the effect of angular frequency on the resulted quantities.

• 동력기계공학회지
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• 제17권1호
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• pp.97-103
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• 2013

Press machine has advantages over other manufacturing machine which can produce large quantities of products in short time so it is widely used in lots of industrial sectors. To obtain the vehicle's weight lightening and rigidity of the body-frame by applying 'Hot stamping' technique is increasing in the automotive field. In this paper, to improve the irregular vibration arose by 800Ton hot stamping press, the research was continued. Bed, slide and main frame are the key part of working precision, so perform structural analysis was conducted, and based on the analyzing results, structural changes were done on the parts where structural deformation occurred.

• Structural Engineering and Mechanics
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• 제54권6호
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• pp.1075-1095
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• 2015

The use of acoustic emission (AE) technique for detecting and monitoring damages and the progress on damages in different structures is widely used and has earned a reputation as one of the most reliable and well-established technique in non-destructive testing (NDT). Acoustic Emission is a very efficient and effective technology used for fracture behavior and fatigue detection in metals, fiberglass, wood, composites, ceramics, concrete and plastics. It can also be used for detecting faults and pressure leaks in vessels, tanks, pipes, as well as for monitoring the progression of corrosion in welding. This paper reviews major research developments over the past few years in application of acoustic emission in numerous engineering fields, including manufacturing, civil, aerospace and material engineering.

• The Journal of Advanced Prosthodontics
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• 제8권6호
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• pp.439-448
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• 2016

PURPOSE. The purposes of this study are to evaluate the internal and marginal adaptation of two widely used CAD/CAM systems and to study the effect of porcelain press veneering process on the prosthesis adaptation. MATERIALS AND METHODS. Molar of a lower jaw typodont resin model was prepared by adjusting a 1.0 mm circumferential chamfer, an occlusal reduction of 2.0 mm, and a $5^{\circ}$ convergence angle and was duplicated as an abrasion-resistant master die. The monolithic crowns and copings were fabricated with two different CAD/CAM system-Ceramil and Zirkonzahn systems. Two kinds of non-destructive analysis methods are used in this study. First, weight technique was used to determine the overall fitting accuracy. And, to evaluate internal and marginal fit of specific part, replica technique procedures were performed. RESULTS. The silicone weight for the cement space of monolithic crowns and copings manufactured with Ceramil system was significantly higher than that from Zirkonzahn system. This gap might cause the differences in the silicone weight because the prostheses were manufactured according to the recommendation of each system. Marginal discrepancies of copings made with Ceramil system were between 106 and $117{\mu}m$ and those from Zirkonzahn system were between 111 and $115{\mu}m$. Marginal discrepancies of copings made with Ceramil system were between 101 and $131{\mu}m$ and those from Zirkonzahn system were between 116 and $131{\mu}m$. CONCLUSION. Marginal discrepancy was relatively lower in Ceramil system and internal gap was smaller in Zirkonzahn system. There were significant differences in the internal gap of monolithic crown and coping among the 2 CAD/CAM systems. Marginal discrepancy produced from the 2 CAD/CAM systems were within a reported clinically acceptable range of marginal discrepancy.

• Smart Structures and Systems
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• 제25권3호
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• pp.301-310
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• 2020

The laser ultrasonic technique is gaining popularity for nondestructive evaluation (NDE) applications because it is a noncontact and couplant-free method and can inspect a target from a remote distance. For the conventional laser ultrasonic techniques, a pulsed laser is often used to generate broadband ultrasonic waves in a target structure. However, for crack detection using nonlinear ultrasonic modulation, it is necessary to generate narrowband ultrasonic waves. In this study, a pulsed laser is shaped into dual-line arrays using a spatial mask and used to simultaneously excite narrowband ultrasonic waves in the target structure at two distinct frequencies. Nonlinear ultrasonic modulation will occur between the two input frequencies when they encounter a fatigue crack existing in the target structure. Then, a nonlinear damage index (DI) is defined as a function of the magnitude of the modulation components and computed over the target structure by taking advantage of laser scanning. Finally, the fatigue crack is detected and localized by visualizing the nonlinear DI over the target structure. Numerical simulations and experimental tests are performed to examine the possibility of generating narrowband ultrasonic waves using the spatial mask. The performance of the proposed fatigue crack localization technique is validated by conducting an experiment with aluminum plates containing real fatigue cracks.