• Journal of the Korean Geotechnical Society
• /
• v.28 no.5
• /
• pp.77-84
• /
• 2012

The engineering characteristics of natural sediments containing diatom microfossils have been investigated for their abnormal deformation and strength behavior for a few decades. The presence of disk or hollow shape diatoms causes low compressibility, high hydraulic conductivity, and high shear strength of sediments. Some of these unusual differences show the characteristic of diatom owing to the interlocking of large interparticle porosity and angular particles. This phenomenon implies the possible use of diatom as modification materials to change the engineering performance of soil mixtures. This paper describes the engineering characteristics of diatom-kaolin mixture to investigate the engineering properties of diatom modified soils using conventional geotechnical tests and elastic and electromagnetic wave propagation tests. Experimental test results show the performance improvement by increasing diatom contents and the performance degradation by the breakage of interlocking between diatom particles under high effective stress.

• Convergence Security Journal
• /
• v.9 no.2
• /
• pp.79-84
• /
• 2009

Recently, Move Picture Files have the same file format and a compression technique as Window Media Video form. but Moving Pictures using file format and a compression technique have question about Motion blur and compressibility. In this paper, we design and Implement for new Move Picture Solution EZ-MOV using FLV different from developed FLV(Flash Video) in the Macromedia company. EZ-MOV have advantages as follow. first, FLV player is able to compact disk access time and DRM (Digital Rights Management) with a built-in self and unable to an illegal video recording, second, whenever WMV formal file encoded FLV are able to lossless compression to fifty percent, third, FLV is able to Moving Picture streaming no buffering. fourth, FLV file is able streaming service no streaming server. fifth, FLV file is able to streaming service keep pace with download and streaming. sixth, FLV file is able to full duplex service.

• The Korean Journal of Ecology
• /
• v.10 no.2
• /
• pp.63-80
• /
• 1987

Detrended correspondence analysis(DCA) and two way indicator species analysis(TWINSPAN) were applied to Pinus densiflora stands nearby Seoul area in order to classify them into several groups based on herbaceous species and environmental relationships. The eighteen Pinus densiflora stands were perferenially selected, In each stand, 30 to 60 quadrats, (20X20)cm, were randomly estabilished. In each quadrat, all stems for herbaceous plants were recorded by species and their covers were measured. In addition environmental factors such as soil depth, thickness of litter layer, soil compressibility, tree density, basal area, elevation, slope and exposure were detemined for each stand. Four to twelve soil cores were collected and physical and KDICical properties were determined. This survey was conducted form 15, July, 1985 to 22, September, 1985. Analysis of the vegetation and environmental data were performed with DECORANA and TWINSPAN. Stand ordination (DECORANA) and classification (TWINSPAN) based on herbaceous species suggest that the stands can be classified into five groups in terms of herbaceous species composition and environmental relationships. Type I, Type II, Type III, Type IV and Type V were classified to SUBMESIC-CLO-SED-CANOPY (Artemisia keiskeana, Carex nanella), MESIC-CLOSED CANOPY (Spodiopogon sibiricus, Miscanthus sinensis, Carex nanella, Pteridum aquilinum, Melampyrum rosium), SUBMESIC-OPEN CANOPY (Carex nanella, Spodiopogon sibiricus, Miscanthus sinensis), XERIC-CLOSED CANOPY (Carex nanella, Spodiopogon sibiricus, Carex nanella), and XERIC-OPEN CANOPY (Arundinella hirts, Spodiopogon sibiricus, Carex nanella), respectively. These results were consitent with environmental trends on stan ordination. Application of the ordination and classifiaction to Pinus densiflora stands were effective as a approach on obtaining perliminary ecological information.

• International Journal of Concrete Structures and Materials
• /
• v.7 no.2
• /
• pp.95-110
• /
• 2013

We report various synchrotron radiation laboratory based techniques used to characterize cement based materials in nanometer scale. High resolution X-ray transmission imaging combined with a rotational axis allows for rendering of samples in three dimensions revealing volumetric details. Scanning transmission X-ray microscope combines high spatial resolution imaging with high spectral resolution of the incident beam to reveal X-ray absorption near edge structure variations in the material nanostructure. Microdiffraction scans the surface of a sample to map its high order reflection or crystallographic variations with a micron-sized incident beam. High pressure X-ray diffraction measures compressibility of pure phase materials. Unique results of studies using the above tools are discussed-a study of pores, connectivity, and morphology of a 2,000 year old concrete using nanotomography; detection of localized and varying silicate chain depolymerization in Al-substituted tobermorite, and quantification of monosulfate distribution in tricalcium aluminate hydration using scanning transmission X-ray microscopy; detection and mapping of hydration products in high volume fly ash paste using microdiffraction; and determination of mechanical properties of various AFm phases using high pressure X-ray diffraction.

• Journal of the Korean GEO-environmental Society
• /
• v.6 no.1
• /
• pp.33-44
• /
• 2005

The 'Silt Pond' is 180 hectares in size and contained ultra soft slurry-like soil varying between 3 to 20 meters in thickness. Soil improvement work in the Silt Pond commenced by installing vertical drains in the mid of 1996, following completion of sand spreading up to +4.0m CD. Prior to soil improvement work in the main area of Silt Pond, experimental tests including laboratory tests with a large diameter consolidation cell and pilot tests were carried out to investigate the deformation behavior of an extremely soft soil. Due to its high compressibility, large strain usually occurred in the initial stage of deformation does not comply with Terzaghi's one dimensional consolidation theory. Taking into consideration experimental test results, the soil improvement works were carried out in main area of Silt Pond containing ultra soft soil. This paper presents the case study on improvement of ultra-soft soil.

• Fashion & Textile Research Journal
• /
• v.17 no.6
• /
• pp.1020-1029
• /
• 2015

This paper investigated the wearing performance of knitted fabrics made of air vortex yarns using PTT/tencel/cotton fibres in comparison with ring and compact yarns for emotional garment. Wicking property of knitted fabric made of MVS yarns was worse than those by ring and compact yarns, however, drying property of knitted fabric made of MVS yarns was better than those by ring and compact yarns, which was explained as more water vapor transport due to larger openness between fibres in the MVS yarns than those in the ring and compact yarns. Thermal conductivity of knitted fabric made of MVS was lower than those of ring and compact yarns and maximum heat flow(Q_max) at the transient state of MVS knitted fabric was lower than those of ring and compact yarns, which may be attributed to MVS yarn structure that has parallel fibres in the core part of the yarn and fasciated fibre bundles on the sheath part with roughness on the yarn surface. However, pilling of MVS knitted fabric was better than those by ring and compact yarns, which was caused by less and shorter hairy fibres protruded from MVS yarn surface than those of ring and compact yarns. It was observed that tactile hand of MVS yarn knitted fabrics was stiffer than those of ring and compact yarns knitted fabrics. It was explained by low extensibility and compressibility and high bending and shear rigidities of the MVS yarn knitted fabrics, which resulted in bad wearing performance of MVS knitted fabric.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.11 no.5
• /
• pp.828-836
• /
• 1987

The inclusion of thermophoresis in particle deposition studies has often been treated separately from deposition due to flow characteristics. Also previously reported experimental results on thermophoresis have been studied in the regions of relatively small temperature gradients. In this study, using real-time laser light reflectivity method, we measured the angular dependence of the deposition rates of particles of the cylindrical collector surface, which immerged in laminar flow of a hot gas suspension of small particles. And we extended the previous narrowband results of thermophoretic deposition rates to the regions of large temperature gradients between the hot gas stream and the collector surface. Based on the obtained data, the cylinder's forward stagnation-point region is considerably enriched in particle 'phase' density owing to the compressibility effect, which leads to locally enhanced deposition while the downstream region from the stagnation point inertial force acts in the opposite direction, which tends to centrifuge particles away from the wall, thus the local deposition rates by thermophoresis are reduced.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.7
• /
• pp.947-952
• /
• 2010

Components such as pressure vessel, hydraulic hose assembly, accumulator, hydraulic cylinder, hydraulic valve, pipe, etc., are tested under the impulse-pressure conditions prescribed in ISO and SAE standards. The impulse pressure test machine needs to have a high pressure, a precise control system and a long life. It should satisfy the requirements for fabrication of the impulse tester to generate ultra high pressure in the hydraulic system. In the impulse tester, a servo-valve control system is adopted; although the control application is convenient, it is expensive owing to the cost of developing the system. The type of the control system determines the pressure wave, which affects the components that are tested. In this study, the manufacturing process and the intensifier system design related to the flow, pressure, and the increasing rate of pressure are investigated. The results indicate the ultra high pressure waves in the system.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.17 no.1
• /
• pp.52-60
• /
• 2013

Ejector-diffuser system makes use of high-pressure primary stream to entrain the low-pressure secondary stream through pure shear action between two streams. In general, the flow field in the ejector-diffuser system is highly complicated due to turbulent mixing, compressibility effects. A fatal drawback of the ejector system is in its low efficiency. Many works have been done to improve the performance of the ejector system, but not yet satisfactory. In the present study, a mixing guide vane was installed at the inlet of the secondary stream for the purpose of the performance improvement of the ejector system. A CFD method has been applied to simulate the supersonic flows inside the ejector-diffuser system. The present results obtained were validated with existing experimental data. The mixing guide vane effects are discussed in terms of the entrainment ratio, total pressure loss as well as pressure recovery.

• Coupled systems mechanics
• /
• v.6 no.3
• /
• pp.287-316
• /
• 2017

This paper studies the particularities of the forced vibration of the hydro-elastic system consisting of a moving elastic plate, compressible viscous fluid and rigid wall. This study is made by employing the discrete-analytical solution method proposed in the paper by the authors (Akbarov and Panakhli (2015)). It is assumed that in the initial state the fluid flow is caused by the axial movement of the plate and the additional lineally-located time-harmonic forces act on the plate and these forces cause additional flow field in the fluid and a stress-strain state in the plate. The stress-strain state in the plate is described by utilizing the exact equations and relations of the linear elastodynamics. However, the additional fluid flow field is described with linearized Navier-Stokes equations for a compressible viscous fluid. Numerical results related to the influence of the problem parameters on the frequency response of the normal stress acting on the plate fluid interface plane and fluid flow velocity on this plane are presented and discussed. In this discussion, attention is focused on the influence of the initial plate axial moving velocity on these responses. At the same, it is established that as a result of the plate moving a resonance type of phenomenon can take place under forced vibration of the system. Moreover, numerical results regarding the influence of the fluid compressibility on these responses are also presented and discussed.