• Computers and Concrete
• /
• v.14 no.1
• /
• pp.91-107
• /
• 2014

Using the principle of damage mechanics, zero-thickness pore pressure cohesive elements (PPCE) are used to simulate the casing-cement interface (CCI) and cement-rock interface (CRI). The traction-separation law describes the emergence and propagation of the PPCE. Mohr-coulomb criteria determines the elastic and plastic condition of cement sheath and rock. The finite element model (FEM) of delamination fractures emergence and propagation along the casing-cement-rock (CCR) interfaces during hydraulic fracturing is established, and the emergence and propagation of fractures along the wellbore axial and circumferential direction are simulated. Regadless of the perforation angle (the angle between the perforation and the max. horizontal principle stress), mirco-annulus will be produced alonge the wellbore circumferential direction when the cementation strength of the CCI and the CRI is less than the rock tensile strength; the delamination fractures are hard to propagate along the horizontal wellbore axial direction; emergence and propagation of delamination fractures are most likely produced on the shallow formation when the in-situ stresses are lower; the failure mode of cement sheath in the deep well is mainly interfaces seperation and body damange caused by cement expansion and contraction, or pressure testing and well shut-in operations.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.24 no.4
• /
• pp.19-25
• /
• 1979

Lowland and upland rice were grown under the both of lowland and upland conditions. Ecological variations in plant characteristics such as plant height, leaf emergence, length of leaf blade, leaf angle, leaf width, heading date, culm length, panicle length and straw weight were observed. Plant height, leaf emergence and heading were accelerated under the lowland condition for both lowland and upland varieties, while leaf length, leaf angle, leaf breadth, number of leaves were increased in upland condition for both lowland and upland varieties.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.12
• /
• pp.1196-1204
• /
• 2001

The rivulet is a narrow stream of liquid flowing down a solid surface. When the rivulet\`s flow rate exceeds a certain limit, it tends to meander exhibiting the instability of its interface. This analysis performs a perturbation analysis of this meandering rivulet assuming an inviscid flow possessing contact angle hysteresis at the contact line. The analysis reveals that the contact angle hysteresis as well as the velocity difference across the inter-face, strongly induces the instability of the liquid interface. Moreover, when the rivulet veto-city is low, it is predicted that the axisymmetric disturbance amplifies more rapidly than the anti-axisymmetric disturbance, which explains the emergence of the droplet flow at the low velocity regime.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.39 no.1
• /
• pp.32-44
• /
• 2023

Purpose: The purpose of this study was to investigate the effect of implant connection type on marginal bone loss (MBL) and to analyze the factors that affect MBL. This study focuses on single implants planted in the upper and lower first molar area. Materials and Methods: A total of 87 implants from 68 patients were tracked for a period over 5 years. There were 57 external connection type (EC) implants and 30 internal connection type (IC) implants in 38 males and 30 females. The MBL and EA were measured from intraoral radiograph images taken after 5 years at most. Results: Significant difference in MBL between EC and IC type was observed in patients without GBR or diabetes. Patients without GBR exhibited an MBL of -0.065 ± 0.859 mm in EC type and -0.627 ± 0.639 mm in IC type (P = 0.025). Using multiple regression analysis, a statistically significant negative correlation was observed between MBL and conditions including implant-abutment connection type (β = -0.303), diabetes (β = -0.113), emergence angle > 30° (β = -0.234), and age (β = -0.776). Conclusion: Within this results, IC type implants had less MBL than EC type, and implant prosthesis with emergence angle over 30° showed greater MBL. To minimize the MBL of the implant and ensure implant stability, careful consideration should be given to the EA of implant prosthesis and its connection type.

• International Journal of Internet, Broadcasting and Communication
• /
• v.15 no.1
• /
• pp.126-139
• /
• 2023

At present, naked-eye 3D appears more and more commonly on the facades of urban buildings. It brings an incredible visual experience to the audience by simulating the natural 3D 3D space effect. At the same time, it also creates enormous commercial value for city publicity and commercial advertisements. There is much research on naked-eye 3D visual effects, but for right-angle LED screens. Right-angle LED screen's brand-new expression method that has only become popular in recent years, how to convey a realistic naked-eye 3D effect through two LED screens combined at right angles has become a problem worth exploring. To explore the whole design ideas and production process of the naked-eye 3D impact of the right-angle LED screen, this paper is a preliminary study aimed at understanding the performance principle and expression features. Before the case analysis, first, understand the standard virtual 3D space construction techniques. Combining it with the optical illusion phenomenon, according to the expression principle of the naked-eye 3D effect of the right-angle LED screen, it can be summarized into seven expressions: Shadow, Color contrast, Background structure line, Magnify object, Object out of bounds, Object floating, Fusion of picture and background. By analyzing the optical illusion phenomenon used in the case, we summarized the main performance characteristics of the naked eye 3D effect. The emergence of right-angle LED screens breaks the limitation of a single plane of optical illusion art, perfectly combines building facades with naked-eye 3D visual effects, and provides designers with a brand-new creative platform. Understanding its production principles and main expressive features can help designers enter this innovative platform better.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.12
• /
• pp.1279-1284
• /
• 2012

Micro structures which are widely used at various fields are commonly fabricated by lithograph, etching and laser methods. Recently, with the emergence of micro tools and ultra-precision machine tools, fabrication of the micro structures obtained using end-milling are studied. However, there are some problems due to the diameter of the micro end-mill getting smaller below $100{\mu}m$. The micro run-out resulted from miniaturization of end-mills have influence seriously on accuracy of micro structures. The error of run-out with a tooling jig showed a decrease of about $9.3{\mu}m$. Furthermore, micro structures with width of $30{\mu}m$ could be applied through experiments of slot machining obtained using 30 and $50{\mu}m$ end-mill. Also, narrow angle structures with $30^{\circ}$ angle could be applied through analysis of machining acute angle structures. Based on basic experiments, micro fluidics channels and spiral patterns for air bearing were machined.

• Journal of The Korean Astronomical Society
• /
• v.35 no.3
• /
• pp.143-149
• /
• 2002

In this paper we present a methodology to derive the temporal change of the magnetic shear angle from a series of vector magnetograms, with a high time cadence. This method looks for the minimum change of the shear angle between a pair of magnetograms, free from the $180^{\circ}$ ambiguity, and then accumulates this change over many successive pairs to derive the temporal change of magnetic shear. This methodology will work well if only the successive magnetograms occurred in an active region are well aligned and its helicity sign is reasonably determined. We have applied this methodology to a set of vector magnetograms of NOAA Active Region 9661 on October 19, 2001 by the new digital magnetograph at the Big Bear Solar Observatory (BBSO). For this work we considered well aligned magnetograms whose cross-correlation values are larger than 0.95. As a result, we have confirmed the recent report of Wang et al. that there was the abrupt shear change associated with the X1.6 flare. It is also demonstrated that the shear change map can be an useful tool to highlight the local areas that experienced the abrupt shear change. Finally, we suggest that this observation should be a direct support of the emergence of sheared magnetic fields.

• Journal for History of Mathematics
• /
• v.30 no.1
• /
• pp.31-50
• /
• 2017

This study analyses on the history of uniform convergence, and discusses its educational implications. First, this study inspects 'overflowing of the Euclidean methodology' which was suggested by Lakatos as a cause of tardy appearance of uniform convergence, and reinterprets that cause in the perspective of 'symbolization'. Second, this study looks into the emergence of uniform convergence of Seidel and Weierstrass in this viewpoint of symbolization. As a result, of analysis, we come to know that the definition of uniform convergence had been changed into the theory of 'domain and graph' from that of 'point and function value' by the location change of the quantifier. As these results, this study puts forward an educational suggestion from an angle of epistemological obstacle, concept definition and concept image.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.14 no.1
• /
• pp.43-49
• /
• 2019

Recently, the importance of industrial fieldbus has been highlighted since the emergence of Industry 4.0. In particular, the Ethernet-based fieldbus protocol is actively used in automation systems. This paper proposes a safety fence system based on EtherCAT, a type of Ethernet-based fieldbus, to measure external loads. In order to measure the external loads, a force sensor was connected to an EtherCAT slave that transmits the sensor data to an EtherCAT master in real-time. The master ultimately controls the angle of the safety fence when it detects danger based on the given data. In the future, more effiecient safety fence system will be developed by using a HMI system to communicate with the EtherCAT master to manage safety and by employing multiple sensors to increase the accuracy of the fence system.

• The Plant Pathology Journal
• /
• v.36 no.6
• /
• pp.628-636
• /
• 2020

Morphological (cyst shape, color, and sizes [length (L), maximum width (W), volume and "a" (L/W)]), structural (vulvar cone slope angle [VCSA], surface wrinkle [VCSW], cyst wall thickness, composition, and texture) and biological characteristics (fecundity, hatching, and emergence [number of second-stage juveniles (J2) from a cyst]) in preceding Heterodera glycines (Hg), currently-recorded H. sojae (Hs) and H. trifolii (Ht) were examined by microscopy. Cysts were lemon-shaped, indicating the genus is Heterodera except for Hs that formed frequently globular cysts with significantly flatter VCSA (102.2°) with smooth VCSW than Hg (50.6°) and Ht (82.0°), but not genus Globodera because of the presence of vulvar cone in Hs. Ht was significantly larger in all morphological characteristics than Hg and Hs, suggesting Ht may be diagnosed differentially by cyst sizes and also host plant preferences. Hs showed smaller "a" value with more globular shape and stronger structures with more thickened and strengthened collagen-like texture of cyst wall than Hg and Ht. This suggests Hs may be diagnosed differently by structural characteristics from the others, especially Hg with similar cyst sizes. There were no significant differences in emergence (inoculum potential) among cyst nematodes due to the offset of fecundity and hatching rate; however, the inoculum potential of Hs may be not so persistent as Hg and Ht in fields because of its lower fecundity and higher hatching rate (causing rapid inoculum loss) than the others. These characteristics of cysts provide information useful for simple and differential diagnoses and reliable management of cyst nematodes.