• The Pure and Applied Mathematics
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• v.17 no.4
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• pp.275-288
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• 2010

A one-holed torus ${\Sigma}$(l, 1) is a building block of oriented surfaces. In this paper we formulate the matrix presentations of the holonomy group of a one-holed torus ${\Sigma}$(1, 1) by the gluing method. And we present an algorithm for deciding the discreteness of the holonomy group of ${\Sigma}$(1, 1).

• Elastomers and Composites
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• v.18 no.1
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• pp.8-12
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• 1983

The purpose of this study is to apply in various fields of products economically and practically using the characteristic of ash of holed briquette coal in maximum. According to the test results, the cure rate of ash of holed briquette coal is comparatively late. But it has shown nearly same level of physical properities compared with other fillers except hard clay and grey carbon.

• Structural Engineering and Mechanics
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• v.66 no.3
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• pp.343-351
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• 2018

Brazilian disc test is one of the most widely used experiments in the literature of geo-mechanics. In this work, the pre-holed concrete Brazilian disc specimens are numerically modelled by a two-dimensional discrete element approach. The cracks initiations, propagations and coalescences in the numerically simulated Brazilian discs (each containing a single cylindrical hole and or multiple holes) are studied. The pre-holed Brazilian discs are numerically tested under Brazilian test conditions. The single-holed Brazilian discs with different ratios of the diameter of the holes to that of the disc radius are modelled first. The breakage load in the ring type disc specimens containing an internal hole with varying diameters is measured and the crack propagation mechanism around the wall of the ring is investigated. The crack propagation and coalescence mechanisms are also studied for the case of multi-holes' concrete Brazilian discs. The numerical and experimental results show that the breaking mechanism of the pre-holed disc specimens is mainly due to the initiation of the radially induced tensile cracks which are growth from the surface of the central hole. Radially cracks propagated toward the direction of diametrical loading. It has been observed that for the case of disc specimens with multiple holes under diametrical compressive loading, the breaking process of the modelled specimens may occur due to the simultaneous cracks propagation and cracks coalescence phenomena. These results also show that as the hole diameter and the number of the holes increases both the failure stress and the crack initiation stress decreases. The experimental results already exist in the literature are quit agree with the proposed numerical simulation results which validates this simulation procedure.

• Journal of Environmental Health Sciences
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• v.2 no.1
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• pp.33-36
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• 1975

This study is aimed to increase the heat efficiency and to decrease the evolution of carbon monooxide during the combustion of holed coal-briquet by using of non-covered fire-box, and determined carbon monooxide versus combustion time and number of air-hole by the using of Orsat gas analyzer. The obtained results are as follows (1) Carbon monooxide are evolved the greatest quantity between 3rd and 6th hour from the hegining of combustion. (2) Combustion time of holed coal-briquet is not showed the difference to fire-boxes of A-type ($\phi$60mm) and B-type ($\phi$165mm). (3) Combustion temperature is decreased in turns of 4 air-hole>3 air-hole>2 air-hole to holed coal-briquet.

• Journal of the Korean Mathematical Society
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• v.51 no.2
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• pp.403-426
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• 2014

The purpose of this paper is to find expressions of the Fricke spaces of some basic surfaces which are a three-holed sphere ${\sum}$(0, 3), a one-holed torus ${\sum}$(1, 1), and a four-holed sphere ${\sum}$(0, 4). For this goal, we define the involutions corresponding to oriented axes of loxodromic elements and an inner product <,> which gives the information about locations of axes of loxodromic elements. The signs of traces of holonomy elements, which are calculated by lifting a representation from PSL(2, $\mathbb{C}$) to SL(2, $\mathbb{C}$), play a very important role in determining the discreteness of holonomy groups.

• Advances in concrete construction
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• v.3 no.2
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• pp.113-126
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• 2015

Holed-Incrementally Prestressed Concrete (H-IPC) girders are designed using the following new design concepts. At first, web openings reduce the self-weight of the girder, and also diffuse prestressing tendon anchorages. The reduced end anchoring forces decrease the web thickness of the end sections. Additionally, precast technology help to improve the quality of concrete and to reduce the construction period at the site. For experimentally verification, two 50 m full-scale H-IPC girders are manufactured with different concrete strength of 55 MPa and 80 MPa. The safety, stiffness, ductility, serviceability and crack development of H-IPC girder are measured and compared with each other for different strengths. Both girders show enough strength to carry live load and good stiffness to satisfy the design criteria. The experimental result shows the advantages of using high strength concrete and adopting precast girder. The test data can be used as a criterion for safety control and maintenance of the H-IPC girder.

• Smart Structures and Systems
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• v.22 no.6
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• pp.675-687
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• 2018

In the previous studies on the porous rock strength the effect of pore number and its diameter is not explicitly defined. In this paper crack initiation, propagation and coalescence in Brazilian model disc containing a single cylindrical hole and or multiple holes have been studied numerically using PFC3D. In model with internal hole, the ratio of hole diameter to model diameter was varied between 0.03, 0.17, 0.25, 0.33, and 0.42. In model with multiple hole number of holes was different in various model, i.e., one hole, two holes, three holes, four holes, five holes, six holes, seven holes, eight holes and nine holes. Diameter of these holes was 5 mm, 10 mm and 12 mm. The pre-holed Brazilian discs are numerically tested under Brazilian test. The breakage load in the ring type disc specimens containing an internal hole with varying diameters is measured. The mechanism of cracks propagation in the wall of the ring type specimens is also studied. In the case of multi-hole Brazilian disc, the cracks propagation and b cracks coalescence are also investigated. The results shows that breaking of the pre-holed disc specimens is due to the propagation of radially induced tensile cracks initiated from the surface of the central hole and propagating toward the direction of diametrical loading. In the case of disc specimens with multiple holes, the cracks propagation and cracks coalescence may occur simultaneously in the breaking process of model under diametrical compressive loading. Finally the results shows that the failure stress and crack initiation stress decreases by increasing the hole diameter. Also, the failure stress decreases by increasing the number of hole which mobilized in failure. The results of these simulations were comprised with other experimental and numerical test results. It has been shown that the numerical and experimental results are in good agreement with each other.

• International Journal of Concrete Structures and Materials
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• v.4 no.2
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• pp.77-87
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• 2010

Prestressed concrete (PSC) I-type girders have been used for span length around up to 40 m in domestic region. PSC girders are very cost effective girder type and extending their lengths more than 50 m will bring large benefit in cost. A new design method was proposed by combining two notable design concept in order to extend the applicable span length in this study. First of all, several numbers of openings was introduced in the girder web, and half of the anchorage devices were moved into the openings. In this way, large compressive stress developed at end zone was reduced, and the portion of design load coming from self-weight was reduced as well. Secondly, prestressing force was introduced in the girder not once at the initial stage, but through multiple loading stages. A full scale girder with the length of 50 m with the girder depth of 2 m was fabricated, and a flexural test was conducted in order to verify the performance of newly developed girder. Test results showed that the new holed web design concept can provide a way to design girders longer than 50 meters with the girder height of 2 m.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.11-12
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• 2010

PSC girder with holed web have several benefits. Most of all placing tendon anchorage in the holes can make prestressing forces be loaded stepwise. In addition it can reduce the self-weight of the beams and increase the span length of beams. And holed web might minimize the interference of view. In this study, a 50-meter long full scale multilevel post-tensioned PSC girder was fabricated and modal test was carried out. In order to obtain precise frequency response, vibration exciter was placed at the middle of the girder and excited with several frequencies. Natural frequency and damping ratio were evaluated from FFT and PSD using the obtained frequency response and compared with numerical analysis result.

• Journal of Korea Foresty Energy
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• v.1 no.2
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• pp.28-33
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• 1981

To survey the present qualities of the molded and to present the base line of qualities in manufacture, the charcoal collected at 27 makers through the nation were examined. The molded charcoal examined in this paper, which is made by carbonization and molding of sawdusts from wood industries, is widely used to kindle holed-coal-briquette. The holed-coal-briquette is utilized in cooking and heating as primary energy source of ordinary households in this country. The average qualities of molded charcoal was as follows; ash content 13.95$\%$, weight 184.6g, density 0.47, time of kindling holed-coal-briquette 65.4 min., calorie 5,790 kcal/kg. The ten makers produced inferior qualities, that was 37 per cent of the 27 makers examined. The base line of qualities of molded charcoal was defined as follows; ash content below 17$\%$, weight above 175 g, falling strength above 300 mm, calorie above 5,500 kcal/kg.