• Smart Structures and Systems
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• v.5 no.6
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• pp.633-644
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• 2009

A simple method has been developed to detect the bonding condition of active fiber composites (AFC) adhered to the surface of a host structure. Large deformation actuating capability is one of important features of AFC. Edge delamination in adhesive layer due to large interfacial shear stress at the free edge is typically resulted from axial strain mismatch between bonded materials. AFC patch possesses very good flexibility and toughness. When an AFC patch is partially delaminated from host structure, there remains sensing capability in the debonded part. The debonding size can be determined through axial resonance measured by the interdigitated electrodes symmetrically aligned on opposite surfaces of the patch. The electrical impedance and modal response of the AFC patch in part adhered to an aluminum plate were investigated in a broad frequency range. Debonding ratio of the AFC patch is in inverse proportion to the resonant frequency of the fundamental mode. Feasibility of in-situ detecting the progressive delamination between AFC patch and host plate is demonstrated.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.27 no.2
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• pp.9-15
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• 2019

The initial buckling of thin walled structures does not result in immediate failure. This post buckling capability is used to achieve light weight design, and final failure of thin walled structure is called crippling. To predict the failure load, empirical methods are often used for thin walled structures in design stage. But empirical method accuracy depend on geometry. In this study, experimental, empirical and numerical study of the crippling behavior of I-section beam made of carbon-epoxy are performed. The progressive failure analysis model to simulate the crippling failure is evaluated using the test results. In this study, commercial software LS-DYNA is utilized to compute the collapse load of composite specimen. Six kinds of specimens were tested in axial compression where correlation between analytical and experimental results has performed. From the results, we have partially conclude that the flange width-to-thickness ratio is found to influence the accuracy of empirical and numerical method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.5
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• pp.324-338
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• 2015

Analytical solutions for interaction between seabed and waves such as progressive wave or partial standing wave with arbitrary reflection ratio or standing wave have been developed by many researchers including Lee et al.(2014; 2015a; 2015b; 2015c; 2015d) and Yamamoto et al.(1978). They handled the pore-water pressure as oscillating pore-water pressure and residual pore-water pressure separately and discussed the seabed response on each pore-water pressure. However, based on field observations and laboratory experiments, the oscillating and residual pore-water pressures in the seabed do occur not separately but together at the same time. Therefore, the pore-water pressure should be investigated from a total pore-water pressure point of view. Thus, in this paper, the wave-induced seabed response including liquefaction depth was discussed among oscillating, residual, and total pore-water pressures' point of view according to the variation of wave, seabed, and flow conditions. From the results, in the field of flow with the same direction of progressive wave, the following seabed response has been identified; with increase of flow velocity, the dimensionless oscillating pore-water pressure increases, but the dimensionless residual pore-water pressure decreases, and consequently the dimensionless total pore-water pressure and the dimensionless liquefaction depth decrease.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.64-75
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• 2017

The role of a track subgrade is to provide bearing capacity and distribute load transferred to lower foundation soils. Track subgrade soils are usually compacted by heavy mechanical machines in the field, such that sometimes they are attributed to progressive residual settlement during the service after construction completion of the railway track. The progressive residual settlement generated in the upper part of a track subgrade is mostly non-recoverable plastic deformation, which causes unstable conditions such as track irregularity. Nonetheless, up to now no design code for allowable residual settlement of subgrade in a railway trackbed has been proposed based on mechanical testing, such as repetitive triaxial testing. At this time, to check the DOC or stiffness of the soil, field test criteria for compacted track subgrade are composed of data from RPBT and field compaction testing. However, the field test criteria do not provide critical design values obtained from mechanical test results that can offer correct information about allowable permanent deformation. In this study, a test procedure is proposed for permanent deformation of compacted subgrade soil that is used usually in railway trackbed in the laboratory using repetitive triaxial testing. To develop the test procedure, an FEA was performed to obtain the shear stress ratio (${\tau}/{\tau}_f$) and the confining stress (${\sigma}_3$) on the top of the subgrade. Comprehensive repetitive triaxial tests were performed using the proposed test procedure on several field subgrade soils obtained in construction sites of railway trackbeds. A permanent deformation model was proposed using the test results for the railway track.

• Korean Journal of Cognitive Science
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• v.24 no.3
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• pp.203-235
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• 2013

The goal of this paper is to test the findings about English-speaking children's acquisition of inflectional morphemes in the literature using a large-scale database. For this, we obtained a 4.7-million-word corpus from the CHILDES (Child Language Data Exchange System) database, and analyzed 1,630 British and American children's uses of English derivational morphemes up to age 7. We analyzed the type and token frequencies, type per token ratio (TTR), and the lexical diversity (D) for such inflectional morphemes as the present progressive -ing, the past tense -(e)d, the comparative and superlative -er/est with reference to children's nationality and age groups. To sum up our findings, the correlations between the D value and children's age varied from morpheme to morpheme; e.g. we found no correlation for -ing, a marginal correlation for -ed, and a strong correlation for -er/-est. Our findings are consistent with Brown's (1973) classical observation that children learn progressive forms earlier than the past tense marker. In addition, overgeneralization errors were frequently found for -ed, but rarely for -ing, showing a U-shaped developmental pattern at ages 2-3. Finally, American children showed higher D scores than British children, which showed that American children used inflectional morphemes for more word types compared with British children. The present study has its significance in testing the earlier findings in the literature by setting up well-defined methodology for analyzing the entire CHILDES database.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.413-421
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• 1987

The objective of this study was to evaluate the possibility of sex preselection by gradients methods using bovine serum albumin in rabbits. Artificial insemination with separated sperm was performed, after highly motile sperm were separated by different methods using 6%, 10% and 20% bovine serum albumin. Various characteristics of separated sperm, and the conception rate and secondary sex ratio at artificial insemination with sperm separated by different methods were compared. The results obtained were as follows. 1. The conception rate of sperm separated by bovine serum albumin gradients was higher than th at of control sperm. But secondary sex ratio was not altered by this methods. 2. The sperm separated by bovine serum albumin gradients showed significantly high value in motility, percent of normal sperm and progressive motility as compared with control sperm and revealed the highest sperm recovery when separated with 6% bovine serum albumin. 3. The sperm motility, percent of normal sperm and progressive motility of the highly motile sperm frozen after being separated from raw semen with bovine serum albumin, showed significantly high value than those of control sperm.

• Tunnel and Underground Space
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• v.14 no.1
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• pp.54-68
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• 2004

In this study, scaled model tests were performed on blasting demolition of reinforced concrete structures and the experimental results were analyzed in comparison with the results of numerical analysis. The tests were designed to induce a progressive collapse, and physical properties of the scaled model were determined using scale factors obtained ken dimension analysis. The scaled model structure was made of a mixture of plaster, sand and water at the ratio determined to yield the best scaled-down strength. Lead wire was used as a substitute for reinforcing bars. The scaled length was at the ratio of 1/10. Selecting the material and scaled factors was aimed at obtaining appropriately scaled-down strength. PFC2D (Particle Flow Code 2-Dimension) employing DEM (Distinct Element Method) was used for the numerical analysis. Blasting demolition of scaled 3-D plain concrete laymen structure was filmed and compared to results of numerical simulation. Despite the limits of 2-D simulation the resulting demolition behaviors were similar to each other. Based on the above experimental results in combination with bending test results of RC beam, numerical analysis was carried out to determine the blasting sequence and delay times. Scaled model test of RC structure resulted in remarkably similar collapse with the numerical results up to 900㎳ (mili-second).

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.504-506
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• 1993

The Joint Photographic Experts Group (JPEG) standard was proposed by the International Standardization Organization (ISO/SC 29/WG 10) and the CCITT SG VIII as an international standard for digital continuous-tone still image compression. The JPEG standard has been widely accepted in electronic imaging, computer graphics, and multi-media applications, however, due to the lossy character of the JPEG compression its application in the field of medical imaging has been limited. In this paper, the JPEG standard was applied to a series of head sections of magnetic resonance (MR) images (256 gray levels, $256{\times}256$ size) and its performance was investigated. For this purpose, DCT-based sequential mode of the JPEG standard was implemented using the CL550 compression chip and progressive and lossless coding was implemented by software without additional hardware. From the experiment, it appears that the compression ratio of about 10 to 20 was obtained for the MR images without noticeable distortion. It is also noted that the error signal between the reconstructed image by the JPEG and the original image was nearly random noise without causing any special-pattern-related artifact. Although the coding efficiency of the progressive and hierarchical coding is identical to that of the sequential coding in compression ratio and SNR, it has useful features In fast search of patient Image from huge image data base and in remote diagnosis through slow public communication channel.

• Journal of Sasang Constitutional Medicine
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• v.15 no.2
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• pp.64-74
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• 2003

Objectives : To evaluate the properness and effectiveness of the question categories concerning 'total physiognomy', used in Iksan Wonkwang Oriental Medicine. Methods: We statistically analyzed data from those 1335 patients focussing on 'relative discrimination ability' to sasang constructions and 'response ratio'. Patients included in this research are only those who had been well treated in Iksan Wonkwang Oriental Medicine during the Period of three years from 2000 to 2002. The data are obtained through the electronic chart developed by Kim Jong-Yeol, and analyzed using the statistical Package SPSS. Results: The first category for discriminating Taeum type, 'heavy and looking steady', has more discriminating power and effectiveness among women than men, and especially in wemen with an age of 21 or more. The second category for discriminating Soeum type, 'delicate and modest', is more discriminating and effective among men than women, and mostly among men with ages 21-40. The third category for Soyang type, 'fast and brave', is almost equally discriminating and effective to both women and men, especially among women with ages 40 or less and among men with ages 21 or more. Finally, the forth category for discriminating Taeyang type, 'progressive', is neither discriminating nor effective among most the women than men in all age groups. Conclusions: The definition of 'relative discriminating power of constitution' and 'response ratio' are well evaluating the properness and effectiveness of the question categories regarding 'total physiognomy'. The first category is most discriminating and effective among women with ages 20 or less, and the second among 21-40 year old men, the third among women with ages 40 or less and among men with ages 21 or over. The forth category is neither discriminating nor effective.

• Earthquakes and Structures
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• v.15 no.5
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• pp.453-462
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• 2018

Damages to buildings affected by a near-fault strong ground motion are largely attributed to the vertical component of the earthquake resulting in column failures, which could lead to disproportionate building catastrophic collapse in a progressive fashion. Recently, considerable interests are awakening to study effects of earthquake vertical components on structural responses. In this study, detailed modeling and time-history analyses of a 12-story code-conforming reinforced concrete moment frame building carrying the gravity loads, and exposed to once only the horizontal component of, and second time simultaneously the horizontal and vertical components of an ensemble of far-field and near-field earthquakes are conducted. Structural responses inclusive of tension, compression and its fluctuations in columns, the ratio of shear demand to capacity in columns and peak mid-span moment demand in beams are compared with and without the presence of the vertical component of earthquake records. The influences of the existence of earthquake vertical component in both exterior and interior spans are separately studied. Thereafter, the correlation between the increase of demands induced by the vertical component of the earthquake and the ratio of a set of earthquake record characteristic parameters is investigated. It is shown that uplift initiation and the magnitude of tensile forces developed in corner columns are relatively more critical. Presence of vertical component of earthquake leads to a drop in minimum compressive force and initiation of tension in columns. The magnitude of this reduction in the most critical case is recorded on average 84% under near-fault ground motions. Besides, the presence of earthquake vertical components increases the shear capacity required in columns, which is at most 31%. In the best case, a direct correlation of 95% between the increase of the maximum compressive force and the ratio of vertical to horizontal 'effective peak acceleration (EPA)' is observed.