• Structural Engineering and Mechanics
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• v.6 no.6
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• pp.693-710
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• 1998

This paper concerns studies on the shape formation of post-tensioned and shaped steel domes. The post-tensioned and shaped steel domes, assembled initially at ground level in an essentially flat condition, are shaped to a curved space form and erected into the final position by means of a post-tensioning technique. Based on previous studies on this shape formation principle, three post-tensioned and shaped steel domes have been constructed. The results of the shape formation tests and finite element analyses are reported in this paper. It is found that the first two test domes did not furnish a part-spherical shape as predicted by finite element analyses, because the movements of some mechanisms were not controlled sufficiently. With a revised post-tensioning method, the third dome obtained the theoretical prediction. The test results of the three post-tensioned and shaped domes have shown that a necessary condition to form a desired space shape from a planar layout with low joint stiffnesses is that the movements of all the existing mechanisms must be effectively controlled as indicated by the finite element analysis. The extent of the maximum elastic deformation of a post-tensioned and shaped steel structure is determined by the strength of the top chords and their joints. However, due to the semi-rigid characteristic of the top chord joints, the finite element analyses cannot give a close prediction for the maximum elastic deformations of the post-tensioned and shaped steel domes. The results of the current studies can be helpful for the design and construction of this type of structure.

• Computational Structural Engineering
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• v.9 no.3
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• pp.209-216
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• 1996

The primary objective of this paper is to grasp many characteristics of buckling behavior of latticed spherical domes under various conditions. The Arc-Length Method proposed by E.Riks is used for the computation and evaluation of geometrically nonlinear fundamental equilibrium paths and bifurcation points. And the direction of the path after the bifurcation point is decided by means of Hosono's concept. Three different nonlinear stiffness matrices of the Slope-Deflection Method are derived for the system with rigid nodes and results of the numerical analysis are examined in regard to geometrical parameters such as slenderness ratio, half-open angle, boundary conditions, and various loading types. But in case of analytical model 2 (rigid node), the post-buckling path could not be surveyed because of Newton-Raphson iteration process being diversed on the critical point since many eigenvalues become zero simultaneously.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.546-551
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• 2023

In this study, a beam steering measurement system was developed to perform functions such as far-field beam steering and near-field beam focusing for TX/RX modes in the near file of the AESA radar. The beam steering measurement system consists of a spherical near-field scanner, an antenna positioner, a near-field controller, a network analyzer, a radar control system, a verification radar, a simulated radio, and an AESA radar. Using the developed system, the characteristics of TX/RX patterns before and after installation of radome to AESA radar were measured, and the beam pattern was analyzed through conversion to far field-after near-field measurement.The boresight error of the radar antenna device was measured, and it was confirmed that the main lobes were formed the same before and after the simulated radar dome was mounted.

• Economic and Environmental Geology
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• v.9 no.1
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• pp.45-73
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• 1976

This study has been made for the enlargement of a previous work of 1964 which was carried out by an author of this work emphasizing the stratigraphy, micropaleontology, depositional environment, and structural tectonics of the studied area. The stratigraphic sequences of the area are groupped into four units: (1) basement of Pre-Cretaceous, (2) lower sediments of Late Cretaceous, (3) upper sediments of Late Cretaceous and (4) igneous rocks of Late Cretaceous and Tertiary (?). The oldest rocks consisting of schists and gneisses of Pre-Cambrian and schistose granite' of Jurassic age are exposed at the base of this area on which the thick Cretaceous sediments were deposited. These old rocks are unconformably overlain by the lower sedimens of Late Cretaceous composed of three members, an alternation of black shale and tuffaceous sediments, fine tuff and rhyollite flow in ascending order. The oily material was found from the black shales of the alternation m"ember as semi-solid greaselike material, oily order and microscopic granular spherical material and oily stain. The lower sediments are also overlain, in low-angleunconfromity, by the 'upper sediments having three members, an alternation of volcanic conglomerate and andesitic tuff, rhyollitic tuff and andesite flow in the same order. The igneous suit of diabase, diorites, biotite granite, porphyritic granite and porphyries of the latest Cretaceous and small exposure of pitchstone of Tertiary (?) intruded into the pre-existed rocks above mentioned. Considerable amount of ostra- coda microfossils have been chemically extracted from the black shales of the lower sediments and the identification of the fossils suggests that the depositional environment of the sediments were under fresh or brackish water condition. The distribution of the geology and its tectonic data also suggest a combination of dome and basin structures in the area of San-i peninsula and Jin-do as shown in fig. 8. Between these two units an anticlinal structure was constructed. As a result of this study, a seismic survey in a district between U-su-yong and north coast of Jin-do is recommended to determine the underground features.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.4
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• pp.281-301
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• 1993

It was revealed that the morphology and projection pattern of terminal arbors from single primary afferent are different among distinct fiber types, functional types and the different subdivision of trigeminal sensory nucleus complex(TSNC). But it was not identified the ultrastructural morphology and synaptic connections of terminal arbors from each primary afferent within TSNC. So we employed the intra-axonal horseradish peroxidase(HRP) injection technique to define the terminal arbors of primary afferent fiber from slowly adapting mechanoreceptors in the periodontal ligament of the cat, and examined 66 labeled terminal arbors within the rostrodorsomedial part(Vo.r) of the trigeminal nucleus oralis, electromicroscopically with 90nm serial sections. All the boutons labelled with HRP contained clear, spherical and uniform sized synaptic vesicles(diameter : $47.66{\pm}3.58nm$ ). Most of the labelled boutons were boutons en passant type and they were connected by unmyelinated axonal strand. In which neurofilament and microtubule was not developed but occasionally contained synaptic vesicle in contrast to the myelinated axon. The size of the labelled bouton was relatively small(long diameter : $1.46{\pm}0.24{\mu}m$, short diameter $0.85{\pm}0.26{\mu}m$, average diameter $1.15{\pm}0.24{\mu}m$) and the shape of which varied from dome to elongated shape, but scalloped glomerulus shape was not developed. Each primary ending in Vo.r made synapse with one or two neuronal propiles(average : $1.11{\pm}0.31$), of which, 89.4% of labelled boutons made synapse with only one neuronal pro pile, the remainder, 10.6% of labelled boutons, made synapse with two neuronal propile. So characteristically they made very simple synapse. Most of labelled boutons(80.03%) made asymmetrical synapse only with dendritic shaft or spine, and 6.1% of labelled boutons received symmetrical synapse from pleomorphic vesicle containing axonal ending(p-ending). So presynaptic inhibiton was relatively scarce. Synaptic triad, in which a p-ending is presynaptic both pre-and post-synaptic element of the axo-dendritic contact from the labelled primary ending was not observed.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.3
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• pp.321-347
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• 1994

Muscle spindle afferents from masseter muscle were labelled by the intra-axonal HRP injection and were processed for light microscopic reconstruction. Regions containing terminal arbors scattered in the central portion of the masseteric motor neuron pool (type I a) and those restricted to 2-3 small portion of it (type II) were selected and processed for electronmicroscopic analysis with serial sections. The shape of the labelled boutons was dome or elongated shape. Scalloped or glomerulus shape with peripherial indentation containing pre or postsynaptic neuronal propiles, which is occasionally found in the trigeminal main sensory nucleus and spinal dorsal horn, was not observed. Both type Ia and type II boutons had pale axoplasm and contained clear, spherical vesicles of uniform size(dia : 49-52nm) and occasionally large dense cored vesicles(dia : 87-118nm). The synaptic vesicles were evenly distributed throughout the boutons although there was a slight tendency of vesicles to accumulate at the presynaptic site. The average of short and long diameter(short D. + long D./2) of type I a bouton was smaller than that of type II bouton. All the labelled boutons, which showed prominent postsynaptic density, large synaptic area and multiple synaptic contact, made asymmetrical synaptic contact with postsynaptic neuronal propiles. Most of the type Ia and type II boutons made synaptic contact with only one neuronal propile and boutons which shows synaptic contact or more neuronal propiles was not observed. Most of the type Ia boutons(87.2%) were presynaptic to the soma or proximal dendrite and a few remainder(12.8%) made synaptic contact with dendritic shaft or distal dendrite. In contrast, majority of type II boutons showed synaptic contact with dendritic shaft and remainder with soma or proximal dendrite. In conclusion, terminal boutons which participate in the excitatory monosynaptic jaw jerk reflex made synaptic contact with more proximal region of the neuron, and showed very simple synaptic connection, compared with those from the primary afferenst in the other region of the central nervous system such as spinal dorsal horn and trigeminal main sensory nucleus which assumed to be responsible for the mediating pain, tactile sensation, sensory processing or sensory discrimination.

• Economic and Environmental Geology
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• v.50 no.2
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• pp.105-116
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• 2017

The purpose of this study is to provide the information on genesis of obsidian occurring in the southwestern part of Ulleung Island, Korea, and to discuss its implications for volcanic activity through volcanological and mineralogical properties of obsidian. Obsidian occurs locally at the lower part of the Gombawi welded tuff, showing various complex textures and flow banding. Though obsidian is mostly homogeneous, it is closely associated with alkali feldspar phenocrysts, reddish tuff, and greyish trachyte fragments. The obsidian occurs as wavy, lenticular blocks or lamination composed of fragments. Cooling fractures developed on obsidian glass are characterized by perlitic cracks, orbicular or spherical cracks, indicating that obsidian rapidly quenched to form an amorphous silica-rich phase. It is evident that hydration took place preferentially at the outer rim relative to the core of obsidian, forming alteration rinds. The glassy matrix of obsidian includes euhedral alkali feldspars, diopside, biotite, ilmenite, and iron oxides. Microlites in glassy obsidian are composed mainly of alkali feldspars and ilmenite. Quantitative analysis by EPMA on the obsidian glass part shows trachytic composition with high iron content of 3 wt.%. Accordingly, obsidian formed with complex textures under a rapid cooling condition on surface ground, with slight rheomorphism. Such results might be induced by collapse of lava dome or caldera, which produced the block-and-ash flow deposit and the transportation into valley while keeping high temperatures.