• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.5C
• /
• pp.199-210
• /
• 2012

The effects of tunnelling in weak weathered rock on the behaviour of a pre-existing single pile and pile groups ($3{\times}3$ and $5{\times}5$ pile groups) above a tunnel have been studied by carrying out three-dimensional (3D) elasto-plastic numerical analyses. Numerical modelling of such effects considers the response of the single pile and pile groups in terms of tunnelling-induced ground and pile settlement as well as changes of the shear transfer mechanism at the pile-soil interface due to tunnelling. Due to changes in the relative shear displacement between the pile and the soil at the pile-soil interface with tunnel advancement, the shear stresses and axial pile force distributions along the pile change drastically. Based on the computed results, upward shear stresses are induced up to about Z/L=0.775 from the pile top, while downward shear stresses are mobilised below Z/L=0.775, resulting in a reduction in the axial pile force distribution with depth equivalent to a net increase in the tensile force on the pile. A maximum tensile force of about $0.36P_a$ developed on the single pile solely due to tunnelling, where $P_a$ is the service axial pile loading prior to tunnelling. The degree of interface shear strength mobilisation at the pile-soil interface was found to be a key factor governing pile-soil-tunnelling interaction. Overall it has been found that the larger the number of piles, the greater is the effect of tunnelling on the piles in terms of pile settlement, while changes of the axial pile forces for the piles in the groups are smaller than for a single pile due to the shielding effect. The reduction of apparent allowable pile capacity due to tunnelling-induced pile head settlement was significant, in particular for piles inside the groups.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.2 no.2
• /
• pp.50-61
• /
• 2000

The ground around the portal of a tunnel is the most typical part showing the 3-dimensional mechanical behavior in the tunnel. The portal slope is constructed at the weathered soft rock-mass, and remains as a potential sliding mass. The slope failure around the tunnel portal may happen drastically and induce the great disaster; hence, for the permanent stability several special techniques are required. To solve this problem, the ground around the tunnel portal may be excavated in the arch shape to develop the arching effect in horizontal direction. With the arch-type portal slope, one can reduce considerably the excavation mass and the damage of environments. This approach has not been attempted yet due to the lack of understanding and the well-defined analyzing method, so the retaining wall type portal is more universal. The 3-dimensional finite element analyses were carried out to prove that the arch type is more advantageous in safety and cost than the right angle type. The influence of the tunnel construction sequence and the strength of the rock-mass on the slope stability was investigated by focusing on the maximum shear strain in the slope, and the yield zone at the tunnel face.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.6
• /
• pp.614-627
• /
• 2018

Urban railway lines have been constructed adjacent to residential buildings and urban areas. The expansion of transportation networks and reconstruction of residential buildings in highly populated urban areas require deep excavations in areas adjacent to urban railways. Mobilized soil stresses and changes in the groundwater level induced by deep excavations results in track irregularities in urban railways. In this study, a three-dimensional finite difference model using the commercial program FLAC3D was adopted to estimate the horizontal displacements of earth retaining structures, settlements of backfill, the stability of track irregularity and underground box structure based on the criteria of each railway organization and its relationships. In deep excavations, a change in groundwater level induces relatively very small differences for track gauge irregularities, whereas relatively large differences for longitudinal irregularities of 72.5%, twist irregularities of 83.3%, cross level irregularities of 61.9%, and alignments of 43.3% were found to be the maximum differences when the horizontal displacement of earth retaining wall and settlement of backfill were 65.1% and 21.4%, respectively, because the groundwater level (GWL) on the ground surface-mobilized tensile strength of the underground box structure exceeds the allowable value. Therefore, three-dimensional numerical analysis was performed in this study. Overall, real-time monitoring should be carried out to prevent railway accidents in advance when a deep excavation adjacent to urban railway structures is constructed.

• Journal of Bio-Environment Control
• /
• v.14 no.3
• /
• pp.196-202
• /
• 2005

This research was conducted to determine the amount of water absorbed by a polyacrylamide hydrogel such as Stocksorb C (STSB), effect of salts on inhibition in hydration of STSB, and the hydrogel effects on changes of nutrient concentration in external solution. Absorption of deionized water by STSB reached a maximum of 180 $mL{\cdot}g^{-1}$. Monovalent soluble salts such as $KH_2PO_4,\;KNO_3$, and $(NH_4)_2SO_4$ reduced absorption of the hydrogel, but the degrees of inhibition in absorption were similar in three kinds of salts. Twenty milliequivalents per liter of $Ca_{2+}\;or\;Mg_{2+}$ reduced water absorption of STSB to $14\%$ compared to those of deionized water. Solution absorption was consistently lower in the presence of divalent cations than in the presence of the monovalent cations. But the absorption was unaffected by the uncharged salt such as urea in all concentrations tested. The final $K^+\;and\;NH_4^+-N$ concentrations of the solution remaining after absorption by STSB was higher than those of the initial solution. The soaking of STSB to full strength of Hoagland solution resulted in increase of $NO_3^--N,\;H_2PO_4^-\;and\;SO_4^{2-}$ concentrations in external solution compared to initial solution, reaching 5,300, 250 and 1,500 $mL{\cdot}g^{-1}$, respectively, at 24 hrs after soaking.

• Korean Journal of Materials Research
• /
• v.8 no.11
• /
• pp.1020-1025
• /
• 1998

Irradiation-induced changes in mechanical properties and magnetic parameters were measured and compared to explore possible correlations for Mn-Mo-Ni low alloy steel surveillance specimens which were irradiated to a neutron fluence of $2.3\times10^{19}n/cm^2$(E>1.0MeV) in a typical pressurized water reactor environment at about $288^{\circ}C$. For mechanical property parameters, microvickers hardness, tensile and Charpy impact test were performed and Barkhausen noise amplitude, coercivity, remanence, maximum induction were measured for magnetic parameters. respectively. Results of mechanical property measurements showed an increase in yield and tensile strength, microvickers hardness. 41J indexed $RT_{NDT}$ and a decrease in upper shelf energy irrespective of base and weld metals. However, in the case of tensile properties, the changes in weld metal were negligible compared to the base metal. In the case of magnetic measurements, it is found that magnetic remanence, BN amplitude. BN energy have dropped significantly but coercivity(H,) has increased rapidly after irradiation. In this study. the measurements conducted on surveillance specimens of Mn-Mo-Ni low alloy steel showed that there were strong correlations between mechanical properties and magnetic properties.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.11
• /
• pp.5514-5521
• /
• 2013

This study is an experiment to look into recovering process after maximum anaerobic exercise of career wrestlers and their basic fitness. First, group time results in anaerobic power test did not show meaningful differences between groups in PP, MP, LP field. Second, blood glucose showed meaningful difference in 5-year wrestlers group according to time-wise result (p<.001). Third, time-wise results in blood lactic acid concentration showed meaningful difference all in 5-year, 10-year and 15-year career wrestlers group (p<.001). Fourth, side step and general reaction did not show meaningful differences in all the 3 groups. In conclusion, increase or decrease was seen from and also significant differences were seen from the change of anaerobic power, glucose, lactic acid, concentration, basic physical strength reaction which have influence over athletic performance of players after anaerobic exercise. It was found that 5-year career players group was good at variables of power test and glucose. Reason why recovery capability in connection with degree of fatigue was poor in 15-year career players group seemed to have correlation between career and age.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.1
• /
• pp.23-34
• /
• 2015

Recently a new damper system with Kogome truss structure was developed and its mechanical properties were verified based on the laboratory test. This paper presents a Kagome truss damper external connection method for seismic strengthening of RC frame structural system. The Kagome external connection method, proposed in this study, consisted of building structure, Kagome damper and support system. The method is capable of reducing earthquake energy on the basis of the dynamic interaction between external support and building structures using Kagome damper. The pseudo-dynamic test, designed using a existing RC frame apartment for pilot application of LH corporation, was carried out in order to verify the seismic strengthening effects of the proposed method in terms of the maximum load carrying capacity and response ductility. Test results revealed that the proposed Kagome damper method installed in RC frame enhanced conspicuously the strength and displacement capacities, and the method can resist markedly under the large scaled earthquake intensity level.

• Journal of Powder Materials
• /
• v.17 no.4
• /
• pp.312-318
• /
• 2010

High speed steels (HSS) were used as cutting tools and wear parts, because of high strength, wear resistance, and hardness together with an appreciable toughness and fatigue resistance. Conventional manufacturing process for production of components with HSS was used by casting. The powder metallurgy techniques were currently developed due to second phase segregation of conventional process. The powder injection molding method (PIM) was received attention owing to shape without additional processes. The experimental specimens were manufactured with T42 HSS powders (59 vol%) and polymer (41 vol%). The metal powders were prealloyed water-atomised T42 HSS. The green parts were solvent debinded in normal n-Hexane at $60^{\circ}C$ for 24 hours and thermal debinded at $N_2-H_2$ mixed gas atmosphere for 14 hours. Specimens were sintered in $N_2$, $H_2$ gas atmosphere and vacuum condition between 1200 and $1320^{\circ}C$. In result, polymer degradation temperatures about optimum conditions were found at $250^{\circ}C$ and $480^{\circ}C$. After sintering at $N_2$ gas atmosphere, maximum hardness of 310Hv was observed at $1280^{\circ}C$. Fine and well dispersed carbide were observed at this condition. But relative density was under 90%. When sintering at $H_2$ gas atmosphere, relative density was observed to 94.5% at $1200^{\circ}C$. However, the low hardness was obtained due to decarbonization by hydrogen. In case of sintering at the vacuum of $10^{-5}$ torr at temperature of $1240^{\circ}C$, full density and 550Hv hardness were obtained without precipitation of MC and $M_6C$ in grain boundary.

• Journal of Conservation Science
• /
• v.29 no.2
• /
• pp.161-170
• /
• 2013

The purpose of this study is to find the reasonable plan for the restoration method through the practical repair of excavated costume. The minimal repair only without adding the physical force as far as possible after investigating the state of excavated costume has been progressed in case of excavated costume since it is already degraded and weak due to the characteristics of organic matter at the moment when it is excavated. Moreover, it has been restored as the following course; The restoration has been applied according to the state of excavated costume with the maximum stability by classifying items capable of being restored considering the fabric state of excavated costume. The drawn thread from the weak in strength and the refined thread of the Juasa(simple gauze) or the light degraded silk thread has been used in case of thread for restoration. The cotton fabrics has been used in the fabric of cellulose system, the Juasa or the silk has been used in the silk depending on the kind of fabric in connection with the support fabric, some parts have been dyed with Alnus firma fruit and the persimmon, has been repaired by using the dyed fabric with the clove for the purpose of mothproof-antibacterial treatment. The method to repair has been carried out by classifying according to the state of damage and the way of formation of costume. The needlework method suitable for the part and state of damage by using the basting, the broad-stitching, backstitch, the blind stitch and the hemming stitch in connection with the needlework method for restoration.

• Cartoon and Animation Studies
• /
• s.32
• /
• pp.245-261
• /
• 2013

This paper analyzes films by director Tarsem Singh in relation to the theory of the sublime. The medium of film works in dimensions of both spectacle and narrative. Tarsem's strength mainly comes from spectacle. The visual style of Tarsem is unique and undeniably beautiful, but in a strange and magnificent way, rather than sweet and pleasant. If you accept the premises of Kant and Lyotard that the beautiful is a positive pleasure and the sublime is a negative pain, Tarsem's spectacle is certainly closer to the sublime than the beautiful. The Fall proves the director's ability in both spectacle and narrative. The spectacle of this film is so overwhelmingly huge, and vivid, it easily surpasses spectators' maximum capacity of imagination, which leaves the spectators in awe. Spectacle tends to hinder thinking thus obstruct the flow of narrative, but at the same time it blocks rational suspicion about the narrative. The spectacle of the Fall works as the power to immerse the spectators into the internal logic of the film. Since the spectators are deeply moved by the spectacle, they willingly follow the narrative of the film, the tragic adventure of the heroes which again gives the audience deep catharsis.