• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.620-631
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• 2022

This paper shows the numerical prediction of the change in oil outflow rate according to the orifice shape of a damaged ship by using the computational fluid dynamics (CFD) analysis method. It also provides discharge coefficients for various orifice shapes to be used in theoretical prediction approaches. The oil outflow from the model ship was analyzed using a multiphase flow method under the condition that the Froude and Reynolds number similitudes were satisfied. The present numerical results were verified by comparing them with the available experimental data. Along with the aspect ratio of the orifice and the wall thickness of the cargo tank, the effects of the orifice shapes defined by mathematical figures on the oil outflow were investigated. To consider more realistic situations, the investigation of the ef ect of the crushed iron plate around the damaged part was also included. The numerical results confirmed the change in oil outflow time for various shapes of the damaged part of the oil tank, and discharge coefficients that quantify the viscous effects of those orifice shapes were extracted. To verify the predicted discharge coefficients, they were applied to an oil spill estimation equation. As a result, a good agreement between the CFD and theoretical results was obtained.

• Journal of the Korean GEO-environmental Society
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• v.23 no.9
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• pp.17-23
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• 2022

Using cement as a road subbase is economical, easily modified and supplemented and has excellent road pavement quality control. In addition, cement adheres well to sandy soils without adhesion, and it plays a role of permanently preserving adhesion in viscous soils with adhesion, so it can be widely applied as stable treatment with the advantages of increased strength, reduced compressibility. and improved durability. However, while cement is excellent in terms of strength for a road subbase, the material properties mean that it is difficult to maintain and reinforce when cracks or fractures occur due to dry shrinkage, and the pH increases in the ground due to hexavalent chromium eluting from cement. which can cause environmental problems such as groundwater contamination. Therefore, this study evaluates the usability of alternatives in the road base layer such as environmentally cementitious stabilizer and on-site soil generated from the site. We intend to reduce the environmental damage and evaluate the durability. To evaluate the applicability of the site, Environmental stability test and freeze-thaw test and wetting-drying test was conducted to evaluate the strength characteristics of alternative materials on the road through the limited performance evaluation of environmentally cementitious stabilizer. The test ranges were set at mixing ratios of 10%, 20%, and 30% and ages of three days, and 28 days old to evaluate the early strength and reference strength according to the mixing ratio of the environmentally cementitious stabilizer.

• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.73-83
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• 2006

The behaviour characteristics of Granular Compaction Pile (GCP) are mainly governed by the lateral confining pressure mobilized in the soft soil matrix to restrain the bulging failure of the granular compaction pile. The GCP method is most effective in soft soil with undrained shear strength ranging $15{\sim}50kPa$. However, the efficiency of this method reduces the more compressible soil conditions, which does not provide sufficient lateral confinement. In the present study, the GCP method reinforced with uniformly graded permeable concrete is suggested for the extension of application to the soft ground. Also, large triaxial compression tests are conducted on composite-reinforced soil samples for verification of availability of the suggested method and the settlement estimation method of the reinforced GCP is proposed. Furthermore, for the verification of the proposed method, predicted settlements by the proposed method are compared with results of 3-dimensional numerical analyses. In addition, parametric studies are performed together with detailed analyses of relevant design parameters.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.25-32
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• 2007

Because of the increasing use of clayey soil as the backfill in reinfurced soil structures and embankments, nonwoven geotextiles of drain capability have been receiving much attention. However, there are few studies on the deformation behavior analysis of nonwoven geotextiles in reinforced soil structures in the site because nonwoven geotextiles which have low tensile stiffness and higher deformability than geogrids and woven geotextiles, are difficult to measure their deformation by using strain gauges. In this study, it was suggested that a new and more convenient method could measure the deformation behaviour of nonwoven geotextile using a strain gauge and examine the availability of the method by conducting laboratory tests and applying to two geosynthetics reinforced soil (GRS) walls in the site. The result of wide-width tensile test conducted under confining pressure of 70 kPa shows that the local deformation of nonwoven geotextile to be measured with strain gauges has a similar pattern to the total deformation measured with LVDT. In the GRS walls, nonwoven geotextile shows a larger deformation range than the woven geotextile and geogrid. However, the deformation patterns of these three reinforcement materials are similar. The function of strain gauges attached to nonwoven geotextile in the walls works normally for 16 months. Therefore, the method proposed in this study for measuring nonwoven geotextile deformation using a strain gauge has proved useful.

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.143-152
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• 1999

Using a Rheometrics Fluids Spectrometer(RFS II), the steady shear flow and the small-amplitude dynamic viscoelastic properties of three kinds of semi-solid food materials(mayonnaise, tomato ketchup, and wasabi) have been measured over a wide range of shear rates and angular frequencies. The shear rate dependence of steady flow behavior and the angular frequency dependence of dynamic viscoelastic behavior were reported from the experimentally measured data. In addition, some viscoplastic flow models with a yield stress term were employed to make a quantitative evaluation of the steady flow behavior, and the applicability of these models was also examined in detail. Furthermore, the correlations between steady shear flow(nonlinear behavior) and dynamic viscoelastic(linear behavior)properties were discussed using the modified power-law flow equations. Main results obtained from this study can be summarized as follows : (1) Semi-solid food materials are regarded as viscoplastic fluids having a finite magnitude of yield stress, and their flow behavior shows shear-thinning characteristics, exhibiting a decrease in steady flow viscosity with increasing shear rate. (2) The Herschel-Bulkley, Mizrahi-Berk, and Heinz-Casson models are all applicable to describe the steady flow behavior of semi-solid food materials. Among these models, the Heinz-Casson model has the best validity. (3) Semi-solid food materials show a stronger shear-thinning behavior at shear rate region higher than a critical shear rate where a more progressive structure breakdown takes place. (4) Both the storage and loss moduli are increased with increasing angular frequency, but they have a slight dependence on angular frequency. The elastic behavior is dominant to the viscous behavior over a wide range of angular frequencies. (5) All of the steady flow, dynamic, and complex viscosities are well satisfied with the power-law model behavior. The relationships between steady shear flow and dynamic viscoelastic properties can well be described by the modified forms of the power-law flow equations.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.11
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• pp.140-149
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• 1996

Cursive characters are written on an economical principle to reduce the motion of a pen in the limit of distinction between characters. That is, the pen is not lifted up to move for writing a next stroke, the pen is not moved at all, or connected two strokes chance their shapes to a similar and simple shape which is easy to be written. For these reasons, strokes and korean alphabets are not only easy to be changed, but also difficult to be splitted. In this paper, we propose a curvature stroke modeling method for splitting and matching by using a structural primitive. A curvature stroke is defined as a substroke which does not change its curvanture. Input strokes handwritten in a cursive style are splitted into a sequence of curvature strokes by segmenting the points which change the direction of rotation, which occur a sudden change of direction, and which occur an excessive rotation Each reference of korean alphabets is handwritten in a printed style and is saved as a sequence of curvature strikes which is generated by splitting process. And merging process is used to generate various sequences of curvature strikes for matching. Here, it is also considered that imaginary strokes can be written or omitted. By using a curvature stroke as a unit of recognition, redundant splitting points in input characters are effectively reduced and exact matching is possible by generating a reference curvature stroke, which consists of the parts of adjacent two korean alphasbets, even when the connecting points between korean alphabets are not splitted. The results showed 83.6% as recognition rate of the first candidate and 0.99sec./character (CPU clock:66MHz) as processing time.

• The Korean Journal of Food And Nutrition
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• v.15 no.2
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• pp.144-150
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• 2002

Sweet persimmon were tested in order to identify their use as secondary material which is excellent in function and taste as food. Samples were soaked for 1 and 5 min with NaCl concentration(0, 1 and 3%) at a certain heating temperature(25, 75 and 95$\^{C}$), and then tannin, vitamin C, flavonol, color intensity, sensory test and textural properties were analysed. The results of the analyses were as follows. Tannins were decreased as heating temperature, NaCl concentration and soaking time were increased, especially, that the control was 420 mg% but decreased 228 and 198 mg% at 95$\^{C}$(1 and 3% NaCl concentration) for 5 min. soaked in each. Vitamin C content also decreased more in higher temperature and NaCl concentration than control(122.4 mg%). Color intensity showed higher value in 1. and b than in heating temperature, NaCl concentration and soaked time longer remarkably, but a value decreased. The peel of sweet persimmons was analyzed myricetin(2.0 $\mu$g/g), quercetin(34.5 $\mu$g/g) and kaemperol(1.1$\mu$g/g), but in pre-treatment sample(95$\^{C}$, 1% NaCl concentration and 5 min. soaked) was showed higher myricetin(9.5 $\mu$g/g) and quercetin(5.5 $\mu$g/g). Textural properties were good in pre-treatment sample(95$\^{C}$, 1% NaCl concentration and 5 min. soaked) such as brittleness, cohesiveness, gumminess and chewiness. In sensory analysis, the pre-treatment samples(95$\^{C}$, 1% NaCl concentration and 5 min. soaked and 95$\^{C}$, 3% NaCl concentration and 1 min. soaked) were showed higher point than others.

• Journal of Dairy Science and Biotechnology
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• v.14 no.1
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• pp.71-84
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• 1996

This study was conducted to examine the usability of sorbitol for the manufacture as low-calory ingredient and cryoprotectant against frost damage. When frozen yoghrt was made of replacing sucrose by sorbitol at yoghurt mix, the change of physicochemical and lactic acid bacteria, such as Str. thermophilus, L. bulgaricus, and mixed culture of Str. thermophilus, and L. bulgaricus(1:1), was studied during the frozen storage(-20$^{\circ}$C). During the incubation of yoghurt mix, the rapid growth of lactic acid bacteria in all sample was observed as the increase of sorbitol addition, but sample A and D were almost similar. This results suggested that sucrose could play role of effecting the growth stimulator, otherwise, sorbitol could inhibit the death of microorganism, following the genus. At the survival rate between lactic acid bacteria during freezing of -5$^{\circ}$C by ice cream freezer Str. thermophilus showed 26.19 to 34.76%, L. bulgaricus 3.97 to 5.20%, and mixed culture 17.16 to 40.87% respectively. L. bulgaricus showed the greater lethal rate than other genus. Sample C which mixed sucrose with sorbitol (1:2 ratio) was showed the lowest lethal rate. Therefore, it suggested that the use of this ration could be used for better anti-frost damage. During the storage of -20$^{\circ}$C, the number of lactic acid bacteria generally decreased in the stand point of genus and frozen storage period. The survival of lactic acid bacteria might be the addition of sorbitol which could have the effect of anti-forst damage. In all treatment, lactase activity showed the rapid decrease after freezing. During the period of frozen storage, it was shown the slow decreasing trend. In spite· of decreasing, the result during yoghurt mix incubation -5$^{\circ}$C freezing, and -20$^{\circ}$C frozen storage was different at the level. After 80 days of storage, the lactase activity was similar among all genus and sample. Despite differenting viscosity followed by genus, combination of mix, and pH, the ratio of 1 to 2(sucrose : sorbitol) showed the greatest viscosity. The water holding capacity of frozen yoghurt mix was closely related to viscosity. As increasing sorbitol amounts, hardness and cohesiveness were increased, but elastisity was decreased. The significant differences between sample was inoculated with Str. thermophilus. However, there were not significant difference from the sample inoculated with L. bulgaricus and mixed culture.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.99-107
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• 1984

Naked barley flour(Baekdong cultivar) was examined with respect to its pasting properties by means of Brabender amylograph after adding barley lipids, fatty acids, vegetable oils and emulsifiers at 1% level. Amylogram of barley flour showed a similar gelatinization temperature but higher paste viscosities at all reference points as compared with wheat flour. Barley flour showed lower amylograph curves by defatting with n-hexane, namely reductions in initial gelatinization point, maximum viscosity and setback value. But re-addition of n-hexane extract to the defatted flour essentially reproduced the curve obtained in the undefatted flour. Addition of polar and nonpolar lipids exhibited different effects on the pasting properties of barley flour. Polar lipids generally increased maximum viscosity a little while non-polar lipids increased the maximum viscosity substantially. Addition of increasing amounts of nonpolar lipids was found to progressively increase the maximum viscosity. Addition of fatty acids increaed th maximum viscosity and delayed the peak time. The maximum viscosity of defatted barley flour impregnated with unsaturated fatty acids was higher than that of defatted barley flour impregnated with saturated fatty acids Increasing amounts of linoleic acid were fount to progressively increase the maximum viscosity and to delay the peak time of defatted barley flour. Addition of six vegetable oils lowered the gelatinization temperature and rasied the maximum viscosity and temperature at maximum viscosity. Addition of increasing amount of peanut oil was found to decrease the maximum viscosity. The effect of emulsifiers was greater in undefatted flour than in defatted flour. The maximum viscosity of defatted flour was slightly affected by Methocel 50, Methocel 1500 and Emulthin, and substantially increased by Methocel 4000, sodium polyacrylate and calcium stearyl lactylate.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.1
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• pp.27-34
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• 2006

We investigated the question whether the efficacy of cleaning tear components on RGP lens and preserving the superior wettability of RGP lens depended on the different type of contact lens care system - RGP lens care solution, SCL care solution, combined solution both for SCL and RGP lens or saline solution. The removal efficacy of the deposited protein was examined by Lowry protein assay and Scanning Electro Microscope(SEM) and residual lipid concentration on RGP lens was determined by High Pressure Liquid Chromatology(HPLC). Wettability was assessed with an equilibrium water-in-air contact angle method. When cared by RGP lens solution, it was demonstrated that 62 percent out of the adhered protein on RGP lens were removed and the removal efficacy of RGP lens solution was not only 4 times than saline solution and the alternative but also higher twice than SCL solution. Contrarily, the SCL solution had the most excellent removal efficacy of the adhered protein on SCL. These results suggest that the cleaning efficacy is thought to be affected by the other factors like the viscosity of care solutions, which mutual contact between RGP lens and care solutions is on the increase due to the viscosity enhancer in RGP lens care solution. RGP lens solution had the greatest removing efficacy to cholesterol and the residual cholesterol concentration was decreased to 50%. It is significant for RGP lens to preserve the superior wettability which means the predictive value for comfortable wearing and it showed that the RGP lens solution offered the most excellent efficacy to maintain the surface wettability. Combined solution both for SCL and RGP lens had weak efficacy of cleaning and maintaining wettability for RGP lens compared to RGP lens care solution.