• Journal of the Korean Geotechnical Society
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• v.30 no.4
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• pp.5-19
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• 2014

In this study, the structural analysis is performed on the method of shallow block and deep cement mixing pile, and then their characteristics and associated behaviors were analyzed. In the case of continuous beam analysis, the predicted settlement was very small, and shear force and bending stress are somewhat overestimated. The frame method is similar to numerical analysis in the internal force shallow block and long pile, but because the settlement of pile is underestimated, the additional calculation using the reaction of the long pile is necessary. For soil arching method and piled raft foundation method, the excessive axial force of long pile was predicted because the load sharing of pile is very large compared to the other methods. In the behavior of the shallow block and deep pile method, the settlement of shallow block and contact pressure are much in the center than the edge. In the estimating method considering the interaction between improved material and ground, the load sharing of the soil-cement pile ranges from 20% to 45%, and the stress ratio is 2.0~5.0 less than piled DCM. The maximum member forces at the boundary conditions of pile head are similar, but in fixed head the axial force and vertical displacement are different in accordance with pile arrangement.

• Journal of the Korean earth science society
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• v.31 no.4
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• pp.354-369
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• 2010

The synoptic and kinematic characteristics of a heavy rainfall that occurred in Gangneung region on 22 to 24 October 2006 were investigated using weather maps, infrared images, AWS observation data and NCEP global final analyses data. The total amount of rainfall observed in the region for the period was 316.5 mm, and the instanteneous maximum wind speed was $63.7m\;s^{-1}$. According to the analysis of weather maps, before the starting of the heavy rainfall, an extratropical low pressure system was developed in the middle region of the Korean Peninsula, and an inverted trough was formed in the northern region of the peninsula. In addition, a jet stream on the upper charts of 300 hPa was located over the Yellow Sea and the southern boundary of the peninsula. A cutoff low in the cyclonic shear side of the upper jet streak, which was linked to an anomaly of isentropic potential vorticity, was developed over the northwestern part of the peninsula. And there are analyzed potential vorticity and wind, time-height cross section of potential vorticity, vertical air motion, maximums of the divergence and convergence and vertical distribution of potential temperature in Gangneung region. The analyzed results of the synoptic conditions and kinematic processes strongly suggest that the tropopause folding made a significant role of initializing the heavy rainfall.

• Geotechnical Engineering
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• v.14 no.4
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• pp.177-204
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• 1998

In the present study, a method of quasi-three dimensional stability analysis is proposed for a systematic design of the GRS-RW(Geosynthetic-Reinforced Soil Retaining Wall) system based on the postulated three dimensional failure wedge. The proposed method could be applied to the analysis of the stability of both the straight-line and cove-shaped are. As with skew reinforcements. Maximum earth thrust expected to act on the rigid face wall is assumed to distribute along the depth, and wall displacements are predicted based on both the assumed compaction-induced earth pressures and one dimensional finite element method of analysis. For a verification of the procedure proposed in the present study, the predicted wall displacements are compared with chose obtained from the RMC tests in Canada and the FHWA tests in U.S.A. In these comparisons the wall displacements estimated by the methods of Christopher et at. and Chew & Mitchell are also included for further verification. Also, the predicted wall displacements for the convex-shaped zone reinforced with skew reinforcements are compared with those by $FLAC_{3D}$ program analyses. The assumed compaction-induced earth pressures evaluated on the basic of the proposed method of analysis are further compared with the measurements by the FHWA best wall. A parametric stduy is finally performed to investigate the effects of various design parameters for the stability of the GRS-RW system

• KSBB Journal
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• v.16 no.6
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• pp.603-608
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• 2001

In this study, we studied on the remeval of toluene vapors in a lab-scale biofilter. Biofiltration was performed in a column fed downflow with contaminated air at ambient conditions. The column was packed with mixture of Peat and Calstene(5:3 vol. Ratio), Synthesized media, Bark and Wood chip, which were inoculated with microbial population of selected stains(Pseudomonas. putida, KCCM 11343, ATCC 12633). The microorganisms were immobilized on the bed medium and then biofilm were formed. The biofilter was operated under the conditions of various inlet toluene concentrations for 180 days and treated up to the elimination capacity of maximum 40 g/㎥hr at the inlet load of 30 g/㎥ hr with percentage removals of 20∼90% and gas retention times between 1 and 2 min. The pressure drop was very negligible through the biofilter columps because its value of 0.054 cmH$_2$O/m was much less than others. The effect of operating conditions such as flow rate, inlet toluene concentration and moisture contents on the performance of the biofilter was sequentially investigated in this study.

• Journal of the Korea Institute of Building Construction
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• v.14 no.6
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• pp.615-621
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• 2014

This study suggests the design and assembly drawing of the prefabricated precast concrete arch ammo magazines using the numerical analysis as well as the explosion verification test. The protective capacity of the proposed magazines is identified with the maximum support rotation angles measured by explosion verification tests according to the U.S. Unified Facility Criteria 3-340-02. Using numerical analysis, it is examined that oval-type members are better than the semi-circle ones in terms of protective capacity. Based on this numerical results, the design and assemble drawing for the prefabricated precast concrete arch ammo magazine are developed. It is identified that the structure constructed by invented design and assembly drawing has enough protective capacity against blast pressure caused by 133.75kg TNT explosion. The detonation point cannot be open due to the military security. In sum, it could be concluded that the ammo magazine proposed in this study has reliable protective capacity with enough redundancy. The redundancy means that there are more economic design approach with reducing the curved wall thickness.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.131-138
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• 1997

Silicon carbide films were chemically vapor deposited onto graphite substrates using MTS(Ch3SiCl3) as a source and Ar or H2 as a diluent gas. The experiments were performed at a fixed condition such as a de-position temperature of 130$0^{\circ}C$, a total pressure of 10 torr, and a flow rate of 100 sccm for each MTS and carrier gas. The purpose of this study is to consider the variation of the growth behavior with the addition of each diluent gas. It is shown that the deposition rate leads to maximum value at 200 sccm addition ir-respective of diluent gases and the deposition rate of Ar addition is faster than that of H2 one. It seems that these characteristics of deposition rate are due to varying interrelationship between boundary layer thick-ness and the concentration of a source with each diluent gas addition, when overall deposition rate is con-trolled by mass transport kinetics. The preferred orientation of (220) plane was maintained for the whole range of Ar addition. However, above 200 sccm addition, especially that of (111) plane was more increased in proportion to H2 addition. Surface morphologies of SiC films were the facet structures under Ar addition, but those were gradually changed from facet to smooth structures with H2 addition. Surface roughness be-came higher in Ar, but it became lower in H2 with increasing the amount of diluent gas.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.7
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• pp.32-36
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• 2008

In this study, $In_2O_3-ZnO$ thin films are prepared on quartz substrates by the pulsed laser deposition and their optical and electrical properties are investigated as the function of substrate temperatures ($200{\sim}600^{\circ}C$) at the fixed oxygen pressure of 200 mTorr. The XRD measurement shows that polycrystalline $In_2O_3-ZnO$ thin films are formed. In the XRD measurement, the intensity of the (400) $In_2O_3$ peak at $35.5^{\circ}$ decreases and that of the (222) $In_2O_3$ peak at $30.6^{\circ}$ increases with the increase substrate temperature up to $500^{\circ}C$. From the result of AFM measurement, the morphology of $In_2O_3-ZnO$ thin films are observed as round-type grains. The lowest surface roughness (6.15 nm) is obtained for the $In_2O_3-ZnO$ thin film fabricated at $500^{\circ}C$. The optical transmittance of $In_2O_3-ZnO$ thin films are higher than 82% in the visible region. The maximum carrier concentration of $2.46{\times}10^{20}cm^{-3}$ and the minimum resistivity of $1.36{\times}10^{-3}{\Omega}cm$ are obtained also for the $In_2O_3-ZnO$ thin film fabricated at $500^{\circ}C$.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.442-449
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• 2017

In this study, a method to inject small amount of activation agent from the outside of the pipeline to the inside wall of the pipe was newly proposed to enhance pumping efficiency of cementitious materials. The activation agent is injected into the slip-layer, which is generally formed in the vicinity of the inside wall of the pipe during pumping cementitous materials. Through the injections, it is expected to decrease viscosity of slip-layer, namely, the friction between the mateirals and the pipe. The proposed method was verified by lab-scale pumping tests with mortars having water to cement ratio of 47%. The tests were performed with two different type of activation agents(superplasticizer and anionic surfactant) and three different amount of the agents(0.14, 0.28, 0.42% of the mortar volume). The compressive strength were measured with and without injecting the activation agent, and the internal pressures of pipeline were measured. When the anionic surfactant was used, there was no change in the compressive strength. As the amount of anionic surfactant increased, the pumping pressure decreased up to 71.4% at the maximum.

• Fashion & Textile Research Journal
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• v.1 no.4
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• pp.376-386
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• 1999

The purpose of this study was to determine the physiological responses and the Subjective sensations of the human subjects when 10 human subjects(5 males and 5 females) were tested with selected ensembles, including the uniforms of students, industrial and bank workers. For the study, garment material and design were selected, which was mostly used in Taegu area by the survey. Thermal manikin and the human subject tests were performed. The results were as follows: 1. There was no significant difference among skin temperature of head by season and among that of breast and back by all variables, however, there was a significant difference among that of belly by gender and that of thigh and shank by season. In addition, there was no significant difference among rectal temperature by gender and season, but there was a significant difference by uniform. 2. Mean skin temperature of male subjects was significantly higher than that of female subjects. Specially in lower environmental condition, the difference got larger. 3. There was a significant difference among purse rate of subjects by uniform, but there was no significant difference among those by gender and season. There were no significant difference among maximum and minimum blood pressure by gender, uniform, and season. 4. There was a significant difference in temperature of chest among gender and uniform, and there was no significant difference in temperature of back by season. In addition, There was a significant difference in humidity of back by uniform and season but there were no significant difference in that by gender. 5. There was a significant difference in humidity sensation by gender, comfort sensation by uniform and season, but there was no significant difference thermal sensation by uniform and season. 6. For the result of regression analysis, we got the regression equations as follows: Clo=1.810 Thickness+0.525, Clo=0.475 weight+0.863.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.5
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• pp.762-771
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• 1987

Friction welding is a fusion process in which the necessary heat is generated by clamping one of the two pieces to be welded in a stationary chuck and rotating the other at high speed with an axially applied load. It is essentially a variation of the pressure welding process but utilizes a novel heating method. In addition to the foregoing advantages, it has also been reported excellent for welding dissimilar materials. Therefore, this study reported on investigating the strength behavior for the frictionally welded domestic structural steel SM45C and SUS304. The results obtained by the experiments are as follows. (1) The highest tensile strength of the best friction welded specimen (B4) is about 3% lower than that of SM-45C base metal, and 9% lower than that of SUS304 base metal. The heat treated specimens (850.deg.C 1hr A.C) have almost same value of tensile strength. (2) The strain of SM45C base metal is 27.3% and that of SUS304 is 42%, that of the best friction welded specimen (B4) appeared as 11.9% which is about 50% lower than the base metal, so, this same phenomenon apeared in all the other welding conditions. (3) The bending strength of SM45C base metal is 123kgf/mm$^{2}$ and that of SUS304 is 127kgf/mm$^{2}$. The best specimen (B4) appeared as 121kgf/mm$^{2}$ which is almost same bending strength for both base metals. (4) The friction welded condition involving maximum strength is determined by P$_{1}$=8kgf/mm$_{2}$, P$_{2}$=22kgf/mm$_{2}$, T$_{1}$=10sec, T$_{2}$=2sec, and amount of upset 7.6mm. (5) The interface of two dissimilar materials are mixed strongly, and welded zone is about 1.03mm and also the heat affected zone is about 2.36mm at SM45C while about 1.85mm at SUS304, therefore the welded zone and heat affected zone are very narrow to compare with those of the other welding materials.