• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.169-178
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• 2009

Ring-type steel fibers (RSFs) of the closed circular shape, have different resistance mechanisms other than straight steel fibers. RSFs also maintain the same value of the orientation factor for the plane enclosed by the fiber ring perimeter. In this research, comparative studies were performed for the panels reinforced with RSFs and with straight steel fibers of $15kg/m^3$ and $30kg/m^3$, respectively. Resisting mechanisms of RSFs were identified and higher toughness indices were experimentally observed for the concrete panels reinforced with RSFs than with straight steel fibers. Orientation factor for the RSF was suggested. It was found that RSFs were more effective in increasing toughness for the panel specimens with relatively thinner thickness than beam specimens.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.1-10
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• 1990

RILEM proposed three point bend test to determine the fracture energy of concrete, but there is discrepancy between the theoritical and the experimental fracture energy of concrete by the influence of self-weight of concrete. This paper presents four point bend test using proving ring in order to take into account the influence of self-weight of concrete. The initial notch to beam depth ratio was varied from 0.2 to 0.6 in order to investigate the variation of fracture energy of concrete according to the variation of initial notch depth. The proposed four point bend test using proving ring was verified to be superior to three point bend test.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.51-59
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• 1994

We constructed travelling type Nd:YAG laser with a negative branch confocal unstable ring (NBCUR) resonator like a Newtonian telescope type using four flat mirror and two positive lenses. Annular output beam was obtained by using scraper mirror. This laser oscillator has 22 optical faces and optical alignment was done by equal inclination interferance method. We inserted a Faraday rotator of permanent magnet type designed in the laboratory for unidirectional operation. We obtained laser output energy of 80m.I with electrical input energy of 70 J. and we obtained that peak power of 0.5MW through Q-switching with BDN dye.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.8
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• pp.690-697
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• 2013

The magnets and vacuum chambers, which are the main facilities of the Pohang light source are installed on the storage-ring girders. System safety and reliability should be taken into account for the precise operating of the main facilities, so vibration analysis is essential to do this. Static and seismic analyses were performed for the design of structure considering safety, and also frequency and response spectrum analyses were performed for the precise alignment. With these results, the effects of surrounding vibration were checked. This paper explains about the design and vibration analysis of girder systems.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1546-1548
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• 1998

Dual mode ring resonators(DMRR) have been fabricated using laser ablated $YBa_2Cu_3O_{7-x}$ superconducting thin films. The transition temperature of YBCO thin films were 85 - 88 K and the film thicknesses were about 5,000 $\AA$. Dual mode ring resonators were patterned by standard photolithography process and wet-etching. Then two-layer metal thin films (Ti/Ag) have been deposited for the ground plane on the back side of substrate by e-beam and thermal evaporation. The input/output feedline angles of each resonator were $60^{\circ}$, $100^{\circ}$, $180^{\circ}$. A network analyzer was used for testing the performance of the resonators in the frequency range of 6-13 GHz at 77 K.

• Steel and Composite Structures
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• v.22 no.1
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• pp.183-201
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• 2016

Perforated steel beams can be optimised by increased beam depth and the moment of inertia combined with a reduced web thickness, favouring the use of original I-section beams. The designers are often confronted with situations where optimisation cannot be carried out effectively, taking account of the buckling risk at web posts, moment-shear transfers and local plastic deformations on the transverse holes of the openings. The purpose of this study is to suggest solutions for reducing these failure risks of tested optimal designed beams under applying loads in a self-reacting frame. The design method for the beams is the hunting search optimisation technique, and the design constraints are implemented from BS 5950 provisions. Therefore, I have aimed to explore the strengthening effects of reinforced openings with ring stiffeners, welded vertical simple plates on the web posts and horizontal plates around the openings on the ultimate load carrying capacities of optimally designed perforated steel beams. Test results have shown that compared to lateral stiffeners, ring and vertical stiffeners significantly increase the loadcarrying capacity of perforated steel beams.

• Journal of the Korean Vacuum Society
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• v.2 no.2
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• pp.131-138
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• 1993

The Project of a superconducting asymmetric multipole wiggler in the 1.5GeV electron storage ring DELTA is in progress. In this work, the influences of nonlinear effects due to the this insertion device are investigated. The standard lattice is tolerable on the beam dynamics problems for all errors which are considered in our work.

• Korean Institute of Interior Design Journal
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• no.13
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• pp.203-215
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• 1997

This Study typed the roof-design in analysis of structural design of the glulam architecture, developed worldwidely, nowaday. For this, it is studied the characters of glulam as the history of glulam architectures, manufacture of glulam, shapes and section of glulam, fireproof and combution of glulam. And it is studied roof-design according to structural type of glulam roof-structure. Conclusively, types of glulam roof design typied as 1)the Simple Beam str., 2)the Multi-Joints continous Beam str. 3)the Hinge str. 4)the Rahmen str. 5)the Archi str. 6)the Grid str. 7)etc str. (Folded-plate str., Radial str., Cylinder Shell str., Ring Dome str., Geodesic Dome str., Conic Coloid Shell str., H.P Shell str. Cantilever Shell str.)

• Tribology and Lubricants
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• v.8 no.2
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• pp.50-63
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• 1992

The minimum oil film thicknesses (MOFT) in the crankshaft main bearings of a 1.5 liter, L-4, gasoline engine are measured and calculated to study the dynamically loaded engine bearing. The MOFT are measured simultaneously at each of the five main bearings using the total capacitance method(TCM). To improve the reliability of the TCM, a reasonable determination method of bearing clearance is introduced and the effects of bearipg cavitation and aeration on the test results are analyzed. Also the crankshaft is grounded by means of a slip ring instead of the friction contact method to improve the test precision. The calculation is based on the model of statically determinate beam, short bearing approximation and Mobility method. From the comparison between the measured and calculated MOFT curves, it is found that a qualitative similarity exists between them, but in all cases, measured MOFT are smaller than that of calculated. The crankshaft vibration and the imbalance of the load distribution between the engine bearings have important influence upon the MOFT curve. So it is found that the calculation result from the model of the statically determinate beam has a limitation in predicting bearing performance.

• The Journal of the Acoustical Society of Korea
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• v.18 no.4E
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• pp.3-9
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• 1999

Deep-water sonar transducers of FFR (Free Flooded Ring) type have been designed using a coupled FE-BEM. The proposed sonar transducers are composed of piezoelectric ceramic tubes and structural steel materials for simple fabrication. In order to have an omnidirectional beam pattern around 30kHz, a conic steel is placed below a piezoelectric tube or a steel disc is placed between two piezoelectric tubes. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Various results are available such as directivity patterns and transmitting voltage responses. The most optimal structure and dimensions of the steel material were calculated, so that the beam patterns of the sonar transducers had +/- 3dB omnidirectivity at 30kHz.