• Journal of the Korean Geotechnical Society
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• v.30 no.10
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• pp.33-44
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• 2014

The preliminary design of suction pile as the supporting system for concrete floating structures was performed for the pilot project of the southwest coast area in Korea. Prior to starting design work, site conditions of the area including ground and hydraulic conditions, and a 100-year return period external force were throughly evaluated. The suction pile for mooring of the offshore floating structures has to satisfy the lateral resistance against external force as well as the penetration ability according to the soil conditions such as soil types, shear strengths, effective stresses, and seepage forces. In the design, the required penetration depths, which were stable for lateral resistance, were evaluated with the diameters of cylindrical suction pile as the final installing ones. And the design suction pressures at each penetrating depths, at which sand boiling did not occur, were assessed through the comparison of penetration and penetrationresistance forces. As a result, it was impossible for suction piles with the diameter range of 3.0~5.0 m to penetrate into required penetration depths. On the other hand, suction piles with the diameter range of 6.0 m and 7.0 m satisfied both the horizontal stability and the penetration ability by design suction pressures at the required penetration depths of 8.5 m and 8.0 m, respectively.

• KSBB Journal
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• v.16 no.5
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• pp.516-522
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• 2001

The large-scale production of antibiotics by filamentous mycelial organism requires and adequate supply of dissolved oxygen. In terms of productivity, it means that oxygen transfer is the rate-limiting step. Therefore, the oxygen transfer coefficients(K$\_$L/A) were determined in a broth involving a filamentous mycelial organism such as Streptomyces avermitilis for use in fermentations. To determine (K$\_$L/A) inn a stirred vessel, a great deal of effort is required to provide all the cells with a sufficient oxygen supply. To overcome the oxygen limitation in a batch culture, a fed-batch culture was applied to control the growth rate by an intermittent supply of nutrients. Thus, it was possible to maintain a suitable dissolved oxygen concentration at a low agitation rate. The optimal agitation speed was 350 rpm at low cell concentrations (below 7 g/L) by considering the efficiency of agitation and shear stress. The (K$\_$L/A) was found to decrease from 64.26 to 29.21h.$\^$-1/ when the biomass concentration was increased from 9.82 to 12.06 g/L. In addition, and increase in viscosity was also observed during the growth phase. By comparing the (K$\_$L/A) values for the various agitation and aeration rates, it was found that the effect of an increase in (K$\_$L/A) by aeration was reduced dramatically at high biomass concentrations. However, this effect was not observed when altering the agitation rate. This suggests that controlling the dissolved oxygen concentration by altering the agitation rate was more efficient than increase the aeration rate.

• KSBB Journal
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• v.11 no.2
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• pp.151-158
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• 1996

For the effective ethanol fermentation, the high concentration of sugar as the substrate of microbial fermentation is required. The most important reason in the inefficient hydrolysis; the easy deactivation of enzyme by temperature or shear stress and the severe inhibition effects of its products. In our work, we comprehended the kinetic characteristics of cellulose and ${\beta}$-glucosidase in the progress of hydrolysis, and observed the potential inhibitory effects of the hydrolyzed products and the deactivation of enzymes. We also tried to present the kinetic model of enzymatic hydrolysis of cellulose, which is applicable to process at the high concentration of sugar. Cellulase and ,${\beta}$-glucosidase exhibit diverse kinetic behaviors. At a level of only 5g/$\ell$ of glucose, the ${\beta}$-glucosidase activity was reduced by more than 70%. This result means that ${\beta}$-glucosldase was the most severely inhibited by glucose. Also at l0g/$\ell$ of cellobiose, the cellulose lost approximately 70% of its activity. ${\beta}$-glucosldase was more sensitive to deactivation than cellulose by about 1.6 times. The comprehensive kinetic model in the range of confidence was obtained and the agreement between the model prediction and the experimental data was reasonably good, testifying to the validity of the model equations used and the associated parameters.

• Journal of Animal Science and Technology
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• v.44 no.2
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• pp.233-238
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• 2002

Meat quality of the domestic pork loins(n=537) classified by 3 groups(5.31-5.50, 5.51-5.70 and $\geq$5.71) according to pH at 24hr post-mortem(pH24) was investigated. In proximate chemical compositions, protein was highest and fat was lowest in the pork loins of pH24 5.31-5.50 group. Water holding capacity increased as pH24 increased, whereas purge loss and cooking loss decreased as pH24 increased. Meat color values(CIE L*, a*, b*, Chroma, Hue and $\Delta$E) decreased as $pH_{24}$ increased. In texture traits, hardness and chewiness were lowest and fat hardness was highest in the pork loins of $pH_{24}{\geq}$5.71 group when compared to the other $pH_{24}$ groups. However, Warner-Bratzler Shear force, springiness and cohesiveness were not significantly different among the pH24 groups(P>0.05). In sensory properties, juiciness and tenderness were highest in $pH_{24}{\geq}$5.71 group. From the results of this study, pork quality was highly related to $pH_{24}$. Therefore, the factors affecting the post-mortem pH, such as stress before slaughter, slaughtering methods, and cooling condition slaughter must be properly controlled and improved to produce high quality pork.

• The Journal of the Petrological Society of Korea
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• v.11 no.3_4
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• pp.169-181
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• 2002

Basic~intermediate dike swarms are pervasively developed in the east of the Ulsan Fault, SE Korea. Most of them intruded initially along the NS-trending extensional fractures which developed under EW extension during the East Sea opening in the Early Miocene (before about 17 Ma). The mean-strikes of the basic dikes intruding into the granites are more clockwise rotated in farther eastern side, i. e.$ N06^{\circ}$E, $Nl5^{\circ}$E, and $N37^{\circ}$E in the western side, in the just vicinities, and in the eastern side of the YBonil Tectonic Line (YTL), respectively. And the mean-strike of the basic dikes nearby shoreline is also most clockwise rotated ($N75^{\circ}$E in the Guryongpo Peninsula). The spatial variance indicates that the dikes, located only in the east of the YTL, experienced horizontal-clockwise rotation, and that the dikes in farther east from the YTL experienced more clockwise rotation. It is, thus, supported that the NNW dextral shear stress, generated by the spreading of the East Sea, was propagated toward inland from eastern continental margin of the Korean Peninsula, and that the YTL is an westernmost limit of the clockwise crustal rotations which are pervasively observed in the vicinities of the Miocene basins, SE Korea.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.601-609
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• 2008

The purpose of this study is to investigate the flexural strengthening effectiveness for the beams combined reinforced with NSM CFRP strips and EBR CFRP strips. To accomplish this objective, a total of nine concrete T beams were tested. From this study, it is found that the flexural stiffness and strength of the beams combined reinforced with NSM and EBR strips were significantly improved compared to the beams strengthened only with NSM CFRP strip. The maximum increase of flexural strength was 347% compared to the beam without CFRP strip. Failure of the beam combined reinforced with NSM and EBR strips (T shape) is initiated by debonding of EBR strips attached on the bottom face, and it was succeeded a part of separatio-n of NSM strips along the longitudinal direction and secondly failure of NSM strips was occurred, eventually sudden explosive failure with the separation of concrete cover in the shear region. This result shows that the NSM and EBR strips have good combination to resist applied load and the combined reinforcement with NSM and EBR strips can redistribute appropriately the total stress subjected concrete beam to the EBR and NSM strips.

• Tunnel and Underground Space
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• v.25 no.4
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• pp.320-331
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• 2015

This paper presents a case study of an enhanced geothermal system(EGS) demonstration project conducted in $Gro{\ss}$ $Sch{\ddot{o}}nebeck$, Northerm Germany, focusing on hydraulic stimulation. The project was conducted with doublet system in sandstone and volcanic formations at 4 - 4.4 km depth. Under normal faulting to strike-slip faulting stress regime, hydraulic stimulations were conducted at injection and production wells by massive waterfrac and gel-proppant fracturing. Injectivity index increased from $0.97m^3/(hr^*MPa)$ to $7.5m^3/(hr^*MPa)$ and productivity index increased from $2.4m^3/(hr^*MPa)$ to $10.1m^3/(hr^*MPa)$ by a series of hydraulic stimulations at both wells. After circulation tests through injection and production wells, however, productivity index decreased from $8.9m^3/(hr^*MPa)$ to $0.6m^3/(hr^*MPa)$ in two years. Slip tendency analysis for the stimulation in volcanic layer estimated the required pressure for shear slip and its preferred orientations and it showed reasonable match with actual stimulation results. Through the microseismicity observation for the stimulation of volcanic formation, only 80 seismic events with its moment magnitudes in -1.8<$M_W$<-1.0 were observed, which are unexpectedly low for EGS hydraulic stimulation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.10
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• pp.649-657
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• 2017

A rupture in a high-pressure pipe causes the fluid in the pipe to be discharged in the atmosphere at a high speed resulting in a supersonic jet that generates the compressible flow. This supersonic jet may display complicated and unsteady behavior in general. In this study, Computational Fluid Dynamics (CFD) analysis was performed to investigate the compressible flow generated by a supersonic jet ejected from a high-pressure pipe. A Shear Stress Transport (SST) turbulence model was selected to analyze the unsteady nature of the flow, which depends upon the various gases as well as the diameter of the pipe. In the CFD analysis, the basic boundary conditions were assumed to be as follows: pipe of diameter 10 cm, jet pressure ratio of 5, and an inlet gas temperature of 300 K. During the analysis, the behavior of the shockwave generated by a supersonic jet was observed and it was found that the blast wave was generated indirectly. The pressure wave characteristics of hydrogen gas, which possesses the smallest molecular mass, showed the shortest distance to the safety zone. There were no significant difference observed for nitrogen gas, air, and oxygen gas, which have similar molecular mass. In addition, an increase in the diameter of the pipe resulted in the ejected impact caused by the increased flow rate to become larger and the zone of jet influence to extend further.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.575-583
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• 2017

Various types of flow patterns around the stepped weir and spillway, such as the skimming flow over such structures and the wave-type flow with a standing undular hydraulic jump and roller downstream of the structures, are developed in open channels. Unsteady three-dimensional numerical simulations are carried out using a hybrid RANS-LES turbulence modeling approach and the volume of fluid method for resolving free surface fluctuations to represent the turbulent flow including the skimming flow and wave-type flow over a stepped weir installed in a rectangular channel. The comparison of numerical results with an existing experimental measurement reveals that the present numerical simulations reasonably well reproduce the turbulent flow passing the stepped weir, in terms of time-averaged velocity profiles at selected locations downstream of the weir, flow topology characterized by the wave-type and skimming flows, the maximum height and length of the standing wave and the length of reattachment of recirculating zone. The numerical result further elucidates the distinct flow behaviors of the wave-type and skimming flow by presenting instantaneous intense variations of free surface and velocity vectors, the distributions of Reynolds shear stress and turbulent kinetic energy and three-dimensional complex features of coherent structures and total pressure distribution.

• Economic and Environmental Geology
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• v.13 no.3
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• pp.141-158
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• 1980

A geologic structure could be formed through various processes, because there are a number of factors which control the deformation of the Earth's crust. In geology, we could call it geological epistemology to describe exactly a geologic structure, and call it geological logics to infer logically the deforming process through which the geologic structure had been formed. Degree of legitimacy of geological logics depends upon the degree of exactness of geological epistemology. This study described quantitatively 3-dimensional Hambaek Syncline through computer analysis, and examined qualitatively into its deforming mechanism based on the results of 3-dimensional analysis of the structure. Input data for the computer analysis are dips and dip directions of bedding planes of the structure. The Hambaek Syncline disclose a minor fold group of NE-SW or NNE-SSW trend and a large scale fold of E-W trend. The conclusions of this study are as follows: (1) The fold of E-W trend is primary fold $(F_1)$ and the minor fold group of NE-SW or NNE-SSW trend secondary fold $(F_2)$. (2) Hambaek Syncline is cylindrical type fold. (3) Apparent axial trace of Hambaek syncline does not coincide with true axial trace. The apparent axial trace is $N70^{\circ}-80^{\circ}W$ in Gohan and Sabuk area, and changes to $N70^{\circ}-80^{\circ}E$ in the westward of the area, while the true axial trace is $N40^{\circ}-70^{\circ}W$ in the former, and $N60^{\circ}-80^{\circ}E$ in the latter area. (4) Westward dipping of axial plane of the minor fold group of NE-SW or NNE-SSW trend can be attributed to simple shear movements along overthrusts. (5) Angle between axial trace and the directional trace of the maximum principal compressive stress $({\sigma}_1)$ may not be perpendicular each other. The angle between them is governed by the following factors; 1) the plunge of fold axis 2) the dip of axial surface 3) cylindrisity (6) The mean axial trace of Hambaek Syncline $(F_1)$ is $N45.6^{\circ}W$, and the directional trace of ${\sigma}_1$ is $N52.4^{\circ}E$ (7) The mean axial trace of the minor fold group of NE-SW or NNE-SSW trend $(F_2)$ is $N21^{\circ}E$, and the directional trace of ${\sigma}_1$ is $N22^{\circ}W$.