• Structural Engineering and Mechanics
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• v.35 no.1
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• pp.99-117
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• 2010

Beam-column joints are the key structural elements, which dictate the behavior of structures subjected to earthquake loading. Though large experimental work has been conducted in the past, still various issues regarding the post-yield behavior, ductility and failure modes of the joints make it a highly important research topic. This paper presents experimental results obtained for eight beam-column joints of different sizes and configuration under cyclic loads along with the analytical evaluation of their response using a simple and effective analytical procedure based on nonlinear static pushover analysis. It is shown that even the simplified analysis can predict, to a good extent, the behavior of the joints by giving the important information on both strength and ductility of the joints and can even be used for prediction of failure modes. The results for four interior and four exterior joints are presented. One confined and one unconfined joint for each configuration were tested and analyzed. The experimental and analytical results are presented in the form of load-deflection. Analytical plots are compared with envelope of experimentally obtained hysteretic loops for the joints. The behavior of various joints under cyclic loads is carefully examined and presented. It is also shown that the procedure described can be effectively utilized to analytically gather the information on behavior of joints.

• Wind and Structures
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• v.25 no.1
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• pp.79-100
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• 2017

The use of wind energy resources is developing rapidly in recent decades. There is an increasing number of wind farms in high wind-velocity areas such as the Pacific Rim regions. Wind turbine towers are vulnerable to tropical cyclones and tower failures have been reported in an increasing number in these regions. Existing post-disaster failure case studies were mostly performed through forensic investigations and there are few numerical studies that address the collapse mode simulation of wind turbine towers under strong wind loads. In this paper, the wind-induced failure analysis of a conventional 65 m hub high 1.5-MW wind turbine was carried out by means of nonlinear response time-history analyses in a detailed finite element model of the structure. The wind loading was generated based on the wind field parameters adapted from the cyclone boundary layer flow. The analysis results indicate that this particular tower fails due to the formation of a full-section plastic hinge at locations that are consistent with those reported from field investigations, which suggests the validity of the proposed numerical analysis in the assessment of the performance of wind-farms under cyclonic winds. Furthermore, the numerical simulation allows to distinguish different failure stages before the dynamic collapse occurs in the proposed wind turbine tower, opening the door to future research on the control of these intermediate collapse phases.

• Journal of Korean Neurosurgical Society
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• v.42 no.1
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• pp.1-5
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• 2007

Objective : We studied whether frontal skull base fracture has an impact on the occurrence and recovery of anosmia and/or ageusia following frontal traumatic brain injury (TBI). Methods : Between May 2003 and April 2005, 102 consecutive patients who had hemorrhage or contusion on the frontal lobe base were conservatively treated. Relevant clinical and radiographic data were collected, and assessment of impaired smell and taste sensation were also surveyed up to at least 12 months post-injury. Results : Among 102 patients, anosmia was noted in 22 (21.6%), of whom 10 had ageusia at a mean 4.4 days after trauma. Bilateral frontal lobe injuries were noted in 20 of 22 patients with anosmia and in all 10 patients with ageusia. Frontal skull base fracture was noted in 41 patients, of whom 9 (21.4%) had anosmia and 4 (9.5%) had ageusia. There was no statistical difference in the occurrence of anosmia and ageusia between patients with or without fracture. Of the 22 patients with anosmia, recovery from anosmia occurred in nine (40.9%) at the interval of 6 to 24 months after trauma, of whom six had frontal skull base fracture and three were not associated with fracture. Recovery of anosmia was significantly higher in patients without fracture than those with fracture (p<0.05). Recovery from ageusia occurred in only two of 10 patients at the interval of 18 to 20 months after trauma and was not eminent in patients without fracture. Conclusion : One should be alert and seek possibile occurrence of the anosmia and/or ageusia following frontal TBI. It is suggested that recovery is quite less likely if such patients have fractures on the frontal base, and these patients should wait for at least 6 to 18 months to anticipate such recovery if there is no injury to the central olfactory structures.

• Journal of Korean Neurosurgical Society
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• v.45 no.2
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• pp.90-95
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• 2009

Objective : We aimed to identify clinico-radiological risk factors that may predict unfavorable neurological outcomes in traumatic brain injury (TBI), and to establish a guideline for patient selection in clinical trials that would improve neurological outcome during the early post TBI period. Methods : Initial clinico-radiological data of 115 TBI patients were collected prospectively. Regular neurological assessment after standard treatment divided the above patients into 2 groups after 6 months : the Favorable neurological outcome group (GOS : good & moderate disability, DRS : 0-6, LCFS : 8-10) and the Unfavorable group (GOS : severe disability-death, DRS : 7-29 and death, LCFS : 1-7 and death). Results : There was a higher incidence of age $\geq$35 years, low initial GCS score, at least unilateral pupil dilatation, and neurological deficit in the Unfavorable group. The presence of bilateral parenchymal lesions or lesions involving the midline structures in the initial brain CT was observed to be a radiological risk factor for unfavorable outcome. Multivariate analysis demonstrated that age and initial GCS score were independent risk factors. The majority of the Favorable group patients with at least one or more risk factors showed improvement of GCS scores within 2 months after TBI. Conclusion : Patients with the above mentioned clinico-radiological risk factors who received standard treatment, but did not demonstrate neurological improvement within 2 months after TBI were deemed at risk for unfavorable outcome. These patients may be eligible candidates for clinical trials that would improve functional outcome after TBI.

• Journal of Korean Society of Transportation
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• v.17 no.3
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• pp.117-130
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• 1999

Earthquakes damage roadway bridges and structures, resulting in significant impacts on transportation system Performance and regional economy. Seismic risk analysis (SRA) procedures establish retrofit priorities for vulnerable highway bridges. SRA procedures use average daily traffic volumes to determine the relative importance of a bridge. This research develops a cost-effective transportation network analysis (TAN) procedure for evaluating numerous traffic flow analyses in terms of the additional system cost due to failure. An important feature of the TNA Procedure is the use of an associative memory (AM) approach in the artificial intelligence held. A simple seven-zone network is developed and used to evaluate the TNA procedure. A subset of link failure system states is randomly selected to simulate synthetic post-earthquake network flows. The performance of different AM model is evaluated. Results from numerous link-failure scenarios demonstrate the applicability of the AM models to traffic flow estimation.

• Journal of the Korean Geotechnical Society
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• v.27 no.4
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• pp.51-65
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• 2011

Shear banding, the localization of deformation into thin zones, has a quite practical relevance, as stability and deformation characteristics of earth structures are controlled by the soil behavior within the shear band. In this study, for understanding occurrence and developed pattern of shear band, plane strain compression tests were performed on three soils with different particle-size distribution under various conditions. Digital images were captured during the experiments; then, deformation of a specimen was evaluated by digital image analysis technique. The characteristics of a shear band were evaluated from the state shortly after post-peak occurrence to critical state. Additionally, the statistical procedure was developed to determine the reasonable thickness of a shear band.

• Journal of the Korean Home Economics Association
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• v.38 no.1
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• pp.25-38
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• 2000

This study focuses on the Russian Constructivist Textile Design in the post-revolutionary period, of the early 20th century. Russian textile of the time is highly valued in the west in terms of innovative changes in aesthetic directions, which has become one of the most important centers for the development of new textiles, or the origin of industrial design. Most of brilliant mass-production patterns were produced specially by the pioneers of constructivists such as Stepanova and Popova who were influenced by 'Maxism' through the Revolution regarded themselves as productivists for the proletariat. They were inspired by the avant-garde movements, which were involved with traditionalism, futuristic mechanism, stylization of nature, pure geometrical and abstract form. Early textile design was based on the relationship between the graphic methods of design and the technology because they regarded art as physical, intellectual and technical production. They created all the excitement made from the primary simplest forms of precise mathmatical shapes, such as the circle, the triangle, the rectangle and horizontle and vertical lines. These geometric design can be interpreted as the mechanization of the artists'labor, or methods in line with the technology of mass production, however partly roots in the rich tradition of Russian decorative art. On the other hand, stable crystalline construction on the surface reflect urban architectural complex, and the world of industry in graphic form. They were interested in illusion of movement, cinematic movement of vertical linear rhythms, optical formations and vibrations, by composing a multi-leveled constructions by several spatial planes, or color-field, and combining structures of several intersecting matrices, and superimposing parts of the forms on each other. All these characteristics of the Russian textile designs reflect the complex interactions between 'art and society' of Constructivist's idea and represent the traits of the epoch.

• Journal of the Korean Geographical Society
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• v.39 no.3
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• pp.297-320
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• 2004

Household Register of South Kyongsang Province compiled by the Korean government in 1904 keeps complete details on local houses of eleven out of a total of thirty-one counties in the district. This study examines, band on e analysis of the primary source materials, e specifics of traditional housing of South Kyongsang Province with special reference to the magnitude of housing lots, size of dwellings, land and house ownership, and distribution of thatch and tile roof houses by dong, myon and county. Findings from the survey of the household register suggest that approximately 20 percent of households were established on the private or rented public lands, that 90 percent resided in undersized housing with just one or two rooms besides a kitchen, and that the regional average of dwelling size was no bigger than 2.75 rooms. The fact clarifies that the three-room thatch houses prevailed in South Kyongsang Province about a century ago. The miserable living conditions were tranalated into a constricted personal space of 2 to 4 square meters and a small-size household of less than 4 family members.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.20-21
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• 2008

Ferroelectric vinylidene fluoride-trifluoroethylene ($VF_2$-TrFE) copolymer films were directly deposited on degenerated Si ($n^+$, 0.002 $\Omega{\cdot}cm$) using by dip coating method. A 1 ~ 3 wt% diluted solution of purified vinylidene fluoride-trifluoroethylene ($VF_2$:TrFE=70:30) in a dimethylformamide (DMF) solvent were prepared and deposited on silicon wafers using dip coating method for 10 seconds. After Post-Annealing in a vacuum ambient at 100~200 $^{\circ}C$ for 60 min, upper aluminum electrodes were deposited by thermal evaporation through the shadow mask to complete the MFS structure. The ferroelectric $\beta$-phase peak of films, depending on the annealing temperature, started to show up around $125^{\circ}C$, and the intensity of the peak increased with increasing annealing temperature. Above $175^{\circ}C$, the peak started to decrease. The C-V characteristics were measured using a Precision LCR meter (HP 4284A) with frequency of 1MHz and a signal amplitude of 20 mV. The leakage-current versus electric-field characteristics was measured by mean of a pA meter/DC voltage source (HP 4140B).

• Investigative Magnetic Resonance Imaging
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• v.21 no.4
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• pp.223-232
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• 2017

Purpose: To report the use of multiband accelerated echo-planar imaging (EPI) for resting-state functional MRI (rs-fMRI) to achieve rapid high temporal resolution at 3T compared to conventional EPI. Materials and Methods: rs-fMRI data were acquired from 20 healthy right-handed volunteers by using three methods: conventional single-band gradient-echo EPI acquisition (Data 1), multiband gradient-echo EPI acquisition with 240 volumes (Data 2) and 480 volumes (Data 3). Temporal signal-to-noise ratio (tSNR) maps were obtained by dividing the mean of the time course of each voxel by its temporal standard deviation. The resting-state sensorimotor network (SMN) and default mode network (DMN) were estimated using independent component analysis (ICA) and a seed-based method. One-way analysis of variance (ANOVA) was performed between the tSNR map, SMN, and DMN from the three data sets for between-group analysis. P < 0.05 with a family-wise error (FWE) correction for multiple comparisons was considered statistically significant. Results: One-way ANOVA and post-hoc two-sample t-tests showed that the tSNR was higher in Data 1 than Data 2 and 3 in white matter structures such as the striatum and medial and superior longitudinal fasciculus. One-way ANOVA revealed no differences in SMN or DMN across the three data sets. Conclusion: Within the adapted metrics estimated under specific imaging conditions employed in this study, multiband accelerated EPI, which substantially reduced scan times, provides the same quality image of functional connectivity as rs-fMRI by using conventional EPI at 3T. Under employed imaging conditions, this technique shows strong potential for clinical acceptance and translation of rs-fMRI protocols with potential advantages in spatial and/or temporal resolution. However, further study is warranted to evaluate whether the current findings can be generalized in diverse settings.