• The Journal of Engineering Geology
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• v.8 no.3
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• pp.275-284
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• 1998

Deformation behavior and microcrack development due to uniaxial compressive cyclic loading in the Pocheon granite were investigated using the ultrasonic velocity measurements and the differential strain analysis(DSA). Most microcracks were developed along the direction parallel to the loading axis. Microcracks developed at the early stage of cyclic loading were formed by propagation of pre-existing cracks. Ultrasonic velocity measurement, DSA and measurement of permanent deformation are good tools to represent microcrack development in rock. Since results from each method are slightly different, microcrack development should be interpreted from all three methods. The magnitude of microcracks developed at the early stage of cyclic loading under 80% loading level is twice compared with those under 70% loading level. The highest volumetric crack strain is about 3000, indicating that the Pocheon granite will fail with 0.3% occupation of microcrack in volume.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.545-551
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• 2007

HCl concentration, reaction temperature, and $Ti^{4+}$ concentration are the decisive factors in determining the structure of precipitates in the process of synthesis of $TiO_2$ particles from aqueous $TiCl_4$ solution by precipitation and the volumetric proportion of brookite phase in $TiO_2$ particles can be controlled by these factors. Pure brookite-type $TiO_2$ nanoparticles were synthesized by heating the aqueous $TiCl_4$ solution with no more than 1.0 M of $Ti^{4+}$, in which the concentration of HCl was kept in the range of about 2.53~6.41 M during reaction, at the temperature below $70^{\circ}C$ for 20 h. Also, Pure brookite was finally transformed to a rutile phase via an anatase phase through heat-treatment.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.4
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• pp.66-74
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• 2001

Plate bending process is indispensible in shipbuilding. The process includes press bending process and heating process. Especially the heating process is carried out exclusively by skillful workers. Many researches have been made to automate the heating process. This study was carried out as a fundamental study to develop a efficient analysis method for triangle heating and focused on clarifying the deformation characteristics of plate by triangle heating and essential elements effect on the deformation. In this paper, we proposed an analysis model for thermal-elastic-plastic analysis and simulated the deformation by triangle heating using ANSYS based on the experimental results of Jang et al.(2001). Also, we showed the deformation characteristics more clearly by comparing the deformation due to triangle heating and line heating in case that the total heat input is same. Finally, we investigated the change characteristics of deformation elements according to the volumetric heat input.

• Journal of the Korean GEO-environmental Society
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• v.15 no.5
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• pp.57-65
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• 2014

For economic and technical reasons, it is difficult to obtain high quality undisturbed cohesionless samples, hence most researchers rely on preparing remolded and reconstituted representative samples of sandy soils. In this study, moist tamping, air pluviation, and dry deposition methods were applied to make remolded samples at similar relative densities. A series of isotropically consolidated drained tests were conducted with accompanied by measured elastic wave velocities in order to evaluate a difference between sample preparation methods and relative densities. For the elastic wave velocity measurements, piezoelectric elements were installed on the top and bottom cap of the triaxial device. The results showed that soil behavior relies on sample preparation methods, and that the trend of shear wave velocity was the same with volumetric strain behavior.

• The Journal of the Acoustical Society of Korea
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• v.31 no.4
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• pp.244-252
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• 2012

The purpose of the present study is to investigate the correlations between acoustic properties, such as speed of sound and normalized broadband ultrasound attenuation, and bone mineral density in femur with high fracture risk. The speed of sound and the normalized broadband ultrasound attenuation in 15 bovine femoral trabecular bone samples in vitro were measured by using a through-transmission method with two matched pairs of ultrasonic transducers with center frequencies of 0.5 and 1.0 MHz. The volumetric bone mineral density of the trabecular bone samples was measured by using micro-computed tomography. The bone mineral density exhibited strong correlations with both the speed of sound and the normalized broadband ultrasound attenuation measured by using the 0.5 and the 1.0 MHz transducers. The highest correlation was found between the bone mineral density and the normalized broadband ultrasound attenuation measured by using the 0.5 MHz ultrasonic transducers. The results suggest that the acoustic properties measured in the femur in vitro can be used as indices for the prediction of femoral bone mineral density.

• YAKHAK HOEJI
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• v.52 no.6
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• pp.480-487
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• 2008

We described an estimation of measurement uncertainty in quantitative analysis of 11-nor-9-carboxy-${\Delta}^9$-tetrahydrocannabinol (THCCOOH), the major metabolite of ${\Delta}^9$-tetrahydrocannabinol, in urine sample by solid-phase extraction (SPE) and GC/MS detection. The analytical results were compared and the different contributions to the uncertainty were evaluated. Inter-day and inter-person validation were performed using statistical analysis of several indicative factors. Measurement uncertainty associated with target analyte in real forensic samples was estimated using quality control (QC) data. Traceability of measurement was established through traceable standards, calibrated volumetric glassware and volume measuring device. The major factors of contribution to combined standard uncertainty, were calibration linearity, inter-day repeatability and inter-person reproducibility, while those associated with preparation of analytical standards and sampling volume were not so important considering the degree of contribution. Relative combined standard uncertainties associated with the described method was 12.05% for THCCOOH.

• Geotechnical Engineering
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• v.9 no.4
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• pp.65-82
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• 1993

A series of torsion shear tests were performed to study the drained stress -strain behavior of medium dense Santa Monica Beach sand under various stress paths. The torque was applied to both clockwise and counterclockwise directions at the end of hollow cylinder specimen. Two clip gages had been previously used to measure the changes in wall thickness and diameter of the specimen. In this study, however, the lateral strain was determined by measuring volume changes in specimen. Specimens were prepared by the air pluviation method and gaseous carbon deozide( CO2) was used to measure precisely volumetric strain in specimen. The drained stress -strain behavior of cohesionless Boils during rotation of principal stress directions was analysed based on the results of torsion shear tests. The coupling of mal stress were applied. It was also found from the test results that the atrial strain at failure decreased with increasing value.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.371-379
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• 2005

Adsorption equilibria of the gases $H_2$, $CH_4$, and $C_2H_4$ and their binary mixtures on activated carbon (Calgon co.) have been measured by static volumetric method in the pressure range of 0 to 18 atm at temperatures of 293.15, 303.15, and 313.15 K. From the parameters obtained from single component adsorption isotherm, multi-component adsorption equilibria could be predicted and compared with experimental data. The binary experimental data were applied to four models : extended Langmuir, extended Langmuir-Freundlich, Ideal Adsorbed Solution theory (IAST), and Vacancy Solution Model (VSM). The models were found to describe the experimental data with a reasonable accuracy. Extended L-F model predicts equilibria of mixture better than any other model.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.193-200
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• 2007

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its lower harmful emissions, including $CO_2$, and high thermal efficiency. In particular, natural gas is seen as an alternative fuel for heavy-duty Diesel Engines because of the lower resulting emissions of PM, $CO_2$ and $NO_x$. Almost all CNG vehicles use the PFI-type Engine. However, PFI-type CNG Engines have a lower brake horse power, because of reduced volumetric efficiency and lower burning speed. This is a result of gaseous charge and the time losses increase as compared with the DI-type. This study was conducted to investigate the effect of injection conditions (early injection mode, late injection mode) on the combustion phenomena and performances in the or CNG Engine. A DI Diesel Engine with the same specifications used in a previous study was modified to a DI CNG Engine, and injection pressure was constantly kept at 60bar by a two-stage pressure-reducing type regulator. In this study, excess air ratios were varied from 1.0 to the lean limit, at the load conditions 50% throttle open rate and 1700rpm. The combustion characteristics of the or CNG Engine - such as in-cylinder pressure, indicated thermal efficiency, cycle-by-cycle variation, combustion duration and emissions - were investigated. Through this method, it was possible to verify that the combustion duration, the lean limit and the emissions were improved by control of injection timing and the stratified mixture conditions. And combustion duration is affected by not only excess air ratio, injection timing and position of piston but gas flow condition.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.1 s.19
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• pp.19-26
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• 2002

To provide 3D GSIS data on the internet, 3D data structures need to be researched and applied for spatial analysis for subsurface modeling. As for GSIS software R&D trend the following things have pointed out : 3-dimensional geo-processing technologies, internet-based application system development, distributed processing technologies for large volume of spatial information, real-time geo-data processing methodologies, Among them research scope within Internet-based application system or Web-based GSIS generally contains core parts of software development such as Internet application, large volume of spatial database handling, real-time spatial data processing, spatial data transfer and transformation, and volumetric display of processing results. This study shows the method of providing 3D GSIS on the internet using VRML model, which are made of DEM data, draped aerial photo, and VRML script programming. And it is also studied that offering 3D GSIS engine on the internet and precise texture mapping using satellite image and aerial photos.