• Geomechanics and Engineering
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• v.10 no.2
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• pp.225-245
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• 2016

Settlement of foundations in permafrost regions primarily results from three physical and mechanical processes such as thaw consolidation of permafrost layer, creep of warm frozen soils and the additional deformation of seasonal active layer induced by freeze-thaw cycling. This paper firstly establishes theoretical models for the three sources of settlement including a statistical damage model for soils which experience cyclic freeze-thaw, a large strain thaw consolidation theory incorporating a modified Richards' equation and a Drucker-Prager yield criterion, as well as a simple rheological element based creep model for frozen soils. A novel numerical method was proposed for live computation of thaw consolidation, creep and freeze-thaw cycling in corresponding domains which vary with heat budget in frozen ground. It was then numerically implemented in the FISH language on the FLAC platform and verified by freeze-thaw tests on sandy clay. Results indicate that the calculated results agree well with the measured data. Finally a model test carried out on a half embankment in laboratory was modeled.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1347-1360
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• 2009

A multi-dimensional component for the thermal-hydraulic system analysis code, MARS, was developed for a more realistic three-dimensional analysis of nuclear systems. A three-dimensional and two-fluid model for a two-phase flow in Cartesian and cylindrical coordinates was employed. The governing equations and physical constitutive relationships were extended from those of a one-dimensional version. The numerical solution method adopted a semi-implicit and finite-difference method based on a staggered-grid mesh and a donor-cell scheme. The relevant length scale was very coarse compared to commercial computational fluid dynamics tools. Thus a simple Prandtl's mixing length turbulence model was applied to interpret the turbulent induced momentum and energy diffusivity. Non drag interfacial forces were not considered as in the general nuclear system codes. Several conceptual cases with analytic solutions were chosen and analyzed to assess the fundamental terms. RPI air-water and UPTF 7 tests were simulated and compared to the experimental data. The simulation results for the RPI air-water two-phase flow experiment showed good agreement with the measured void fraction. The simulation results for the UPTF downcomer test 7 were compared to the experiment data and the results from other multi-dimensional system codes for the ECC delivery flow.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.4
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• pp.800-812
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• 2014

The paper provides some results of a new procedure to analyze the hydrodynamic aspects of the interactions between maritime emerged breakwaters and waves by integrating CAD and CFD. The structure is modeled in the numerical domain by overlapping individual three-dimensional elements (Tetrapods), very much like the real world or physical laboratory testing. Flow of the fluid within the interstices among concrete blocks is evaluated by integrating the RANS equations. The aim is to investigate the reliability of this approach as a design tool. Therefore, for the results' validation, the numerical run-up and reflection effects on virtual breakwater were compared with some empirical formulae and some similar laboratory tests. Here are presented the results of a first simple validation procedure. The validation shows that, at present, this innovative approach can be used in the breakwater design phase for comparison between several design solutions with a significant minor cost.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.22 no.2
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• pp.174-181
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• 1996

The novel synthesis of 3-aminopropyl dihydrogen phosphate(3-APPA; 3-Aminopropane phosphoric acid), and its applicability to the skin as a cosmetic raw material in terms of its efficacy and toxicology were presented. The phosphorylation of 3-amino-1-propanol was carried out via cyclization into 6-membered 2, 6-oxaza-phosphoryl ring in the presence of phosphorous oxychloried and an organic base. The subsequent ring-opening hydrolysis and crystallization afforded the highly purified product in 90% isoloated yield. The method is much superior to the previous literature phosphorylation methodsm, as the procedure is simple and high-yielding. To confirm the efficacy of 3-APPA, several activities related to anti-aging capacity were measured. In-vitro human fibroblast, linear and 3-dimensional collagen matrix culture revealed that 3-APPA stimulated the proliferation of fibroblasts, and enhanced the synthesis of collagen, which showed 3-APPA's potency for skin wrinkle reduction. The toxicolgical aspect of 3-APPA was also extensively examined. In vivo toxicity tests such as acute oral toxicity, eye irritation, human patch, and the repeat insult human patch test proved 3-APPA to be a safe material. Thus 3-APPA can be used as an effective anti-aging agent for various cosmetic formulations.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.7
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• pp.512-520
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• 2007

The design of a ground-source heat pump system includes specifications for a ground loop heat exchanger where the heat transfer rate depends on the effective thermal conductivity of the ground and the effective thermal resistance of the borehole. To evaluate these heat transfer properties, in-situ thermal response tests on four vertical test boreholes with different grouting materials were conducted by adding a monitored amount of heat to circulating water. The line-source method is applied to the temperature rise in an in-situ test and extended to also give an estimate of borehole effective thermal resistance. The effect of increasing thermal conductivity of the grouting materials from 0.818 to $1.104W/m^{\circ}C$ resulted in overall increases in effective thermal conductivity by 15.8 to 56.3% and reductions in effective thermal resistance by 13.0 to 31.1%.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.109-116
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• 2012

This paper presents a study on the nonlinear behavior of an innovative bridge girder made from concrete-filled and tied tubular steel arch (CFTA) under static loading. Manufacturing of the CFTA girder may have defects which may highly affect the symmetry and performance of the structure. A simple method is proposed by using stiffness extracted from static test data to detect manufacturing defects of the CFTA girder. A three-dimensional finite element model was used in the numerical analysis in order to verify the method. The proposed method was experimentally validated through static tests of the CFTA girder. The application of the proposed method showed that it is effective in identifying invisible manufacturing defects of the CFTA girder, especially for mass production of a standard type in the factory.

• The Korean Journal of Applied Statistics
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• v.26 no.6
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• pp.1009-1018
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• 2013

Regression analysis is useful to understand the relationship of variables; however, we need to test if the slope of each regression lines is the same when comparing several populations. This paper suggests a new parallelism test for several linear regression lines. We use F-test of ANOVA and Kruskal-Wallis (1952) tests after obtaining slope estimator from a sequential slope. In addition, a Monte Carlo simulation study is adapted to compare the power of the proposed methods with those of Park and Kim (2009).

• Fire Science and Engineering
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• v.17 no.1
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• pp.1-7
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• 2003

In general, small buildings and residence housings rely on manual fire extinguishers instead of automatic fire suppression systems, which causes bigger disasters during the absence of human-beings or in the presence of children or the olders. For this reason, simple structured and low-cost automatic fire extinguisher using fusible metal detector was newly developed and patented. In this paper, some field tests were carried out to investigate its fire suppression performance. As a result, reaction time of the detection parts varied from 2 min 19s to 7 min 20s depending upon the room size and installation position. It was suggested that to reduce reaction time within 3 minutes, fusible metals with lower melting point should be adopted and the installation location should be moved to near ceiling instead of below 1.5 m.

• Asian Journal of Business Environment
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• v.3 no.2
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• pp.23-29
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• 2013

Purpose - The study investigates the obstacles faced by small business owners (SBOs) in accessing finance in the Buffalo City Metropolitan Municipality. The study aims to identify the causes of inaccessibility to finance for SBOs, investigate the role of government agencies in supporting SBOs, assess the extent to which banks support SMMEs, and suggest solutions to ease the challenge of inaccessibility of finance. Research design, data, methodology -We used a triangulation research design, wherein SMME owners and managers in the Buffalo City Metropolitan Municipality were the target population. We used simple random sampling techniques to select respondents, and conducted in-depth interviews to collect qualitative data. Results - We analyzed quantitative data using descriptive statistics, Chi-square tests, and factor analysis. The qualitative data was analyzed using content analysis. The study identifies and discusses the obstacles in accessing finance; the main among which are the lack of collateral security, poor business plans, lack of knowledge, and lack of financial deposit. Conclusions -We urge the banks, government, and government agencies to support the SMME sector, for it remains the economic engine of many African countries and helps in reducing the impact of socio-economic challenges, like unemployment and poverty.

• Journal of Drive and Control
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• v.9 no.4
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• pp.32-41
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• 2012

Most diagnosis methods for servo valves requires installing spool displacement sensor or flow sensor as well as pressure sensor. The measurement of flow is hard to implement and many kinds of servovalves or proportional direction valves do not have a built-in spool displacement sensor. In this study, static performances of servovalve or proportional-direction-valve are studied theoretically and a diagnosis technique, which uses only load pressure and input current signal, is assessed. An experimental setup was made based upon a personal computer and the LabVIEW graphical language. A series of diagnosis tests were performed and the analysis results showed it possible to measure the pressure gain, hysteresis and null bias in a relatively simple methodology.