• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.431-438
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• 1999

An assessment of liquefaction potential is made in principle by comparing the shear stress induced by earthquake to the liquefaction strength of the soil. In this study, a modified method based on Seed and Idriss theory is developed for evaluating liquefaction potential. The shear stress in the ground can be evaluated with seismic response analysis and the liquefaction strength of the soil can be investigated by using cyclic triaxial tests. The cyclic triaxial tests are conducted in two different conditions in order to investigate the factors affecting liquefaction strength such as cyclic shear stress amplitude and relative density. And performance of the modified method in practical examples is demonstrated by applying it to liquefaction analysis of artificial zones with dimensions and material properties similar to those in a typical field. From the result, the modified method for assessing liquefaction potential can successfully evaluate the safety factor under moderate magnitude(M=6.5) of earthquake.

• Journal of Korean Society for Quality Management
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• 제21권2호
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• pp.242-253
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• 1993

The interpretation of the reaction mechanism is significant to produce the high quality welds and understand the welding processes. This investigation is important for the design of welding consumables and the selection of welding process parameters to develop the high quality welds. The objective of this study is to investigate the effect of electrochemical reactions on the transfer of alloy elements between slag and weld metal during submerged arc welding During submerged arc welding weld metal composition is shown to be controlled by two reaction mechanisms in four reaction zones. The responsible reaction mechanisms are thermochemical and electrochemical reactions. The possible reaction sites are the melted electrode tip, the detached droplet, the hot weld pool immediately below the moving electrode, and the cooling and solidifying weld pool behind the moving electrode. The possible reactions in submerged arc welding at different zones of the process is schematically shown in Figure 1.

• Geomechanics and Engineering
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• 제8권6호
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• pp.783-799
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• 2015

In this study, effect of horizontal in situ stress on failure mechanism around underground openings excavated in isotropic, elastic rock zones is investigated. For estimating the plastic zone occurrence, an induced stress influence area approach (Bray Equations) was modified to define critical stress ratio according to the Mohr-Coulomb failure criterion. Results obtained from modified calculations were compared with results of some other analytical solutions for plastic zone thickness estimation and the numerical modelling (finite difference method software, FLAC2D) study. Plastic zone and its geometry around tunnels were analyzed for different in situ stress conditions. The modified equations gave similar results with those obtained from the other approaches. However, safer results were calculated using the modified equations for high in situ stress conditions and excessive ratio of horizontal to vertical in situ stresses. As the outcome of this study, the modified equations are suggested to use for estimating the plastic zone occurrence and its thickness around the tunnels with circular cross-section.

• Proceedings of the Materials Research Society of Korea Conference
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• 한국재료학회 1992년도 추계학술발표강연 및 논문개요집
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• pp.121-121
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• 1992

Deformation behavior of compatible polymer blends was studied using scanning electron, optical, and transmission electron microscopies. Four different compatible systems were employed and charaterized in this investigation : polystyrene(PS) and polyphenylene oxide(PPO), polystyrene(PS) and polyvinlmethylether(PVME), polystyrene(PS) and poly $\alpha$-methylstyrene(P$\alpha$MS). Individual craze and shear deformation zone microstructures were examined by transmission microscopy (TEM). For TEM observations, specimens deformed in-situ on a TEM grid were utilized. Quantiative analysis of these crazes and shear deformation zones was obtained from the nicrodensitometry of the TEM negatives in the manner developed by Lauterwasser and Kramer. Microdensitometry resulys showed that the fibril extension ratio decreased as the PPO content increased in the PS/PPO blends, and finally, for 100% PPO, only shear deformation zones were observed. For the PS/PVME blends, the ribril extension ratio also decreased as the VME content increased. For the PS/P$\alpha$MS blends, the fibril extension ratio increased as the P$\alpha$MS content increased, For the PPO/P$\alpha$MS blends, the fibril extension ratio increased as the P$\alpha$MS content increased.

• Journal of Korean Association for Spatial Structures
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• 제1권2호
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• pp.93-100
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• 2001

A stress-strain relationship for reinforced concrete membrane elements subjected to reversed cyclic loading is quite different to that of concrete cylinder subjected to uniaxial compression. The compressive strength of cracked concrete membrane elements is reduced by cracking due to tension in the perpendicular direction. Based on the three reinforced concrete panel tests, a softened stress-strain curve of concrete subjected to reversed cyclic loading is proposed. The proposed model consists of seven stages in the compressive zones and six stages in the tensile zones. The proposed model is verified by comparing to the test results.

• Journal of the Mineralogical Society of Korea
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• 제2권1호
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• pp.11-17
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• 1989

The kaolin deposits in Hadong-Sancheong area, have been formed by supergene weathering of anorthositic rocks including anorthosite, leucogabbro, and gabbro. Kaolin consists chiefly of halloysite(10$\AA$) and kaolinite with other minerals such as illite, vermiculite, plagioclase, hornblende, quartz amorphous materials(allophane and siica), goethite, and hematite. Goethite and hematite are the major coloring agents of the reddish brown and other colored kaolins. Other common accessory minerals are magnetite, ilmentite, anatase, gibbsite, I/S, C/V, chlorite, lithiophorite, and birnessite. Paragonite, dravite, laumontite, clinozoisite, muscovite, scolecite, stellerite are locally found. Al substitution of Fe in goethite and hematite decreases from the surface zone toward the deeper zone. The kaolin deposits show three horizontal zoning; the upper reddish brown, middle pink, and lower white zones. All the zones are characterized by somewhat different mineralogy. The factors for the formation of kaolin deposits in Hadong-Sancheong area are 1) the presence of anorthositic rocks, 2) the low flat or gentle topography, 3) the favorable climate, and 4) the long-continued preservation of kaolins with-out erosion.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.660-671
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• 2008

The suspension bridge between Myodo and Gwangyang is located in the main navigation channel to Gwangyang Harbor. So, there is need for the collision protection against large vessels. As ship collision protection, artificial island with concrete block quay wall is planned. The risk analysis and non-linear numerical analysis are introduced to consider the ship collision effects. In the Gwangyang bay area, there are some different sedimental conditions in clayey stratums. For a desirable design, we classify into four zones and 2 layers in each zone, and then determine suitable soil properties considering these zones. As a ground improvement under artificial island, DCM and SCP methods are Planned.

• Bulletin of the Korean Chemical Society
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• 제15권1호
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• pp.57-63
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• 1994

Digital simulation program for one-dimensional geometric systems of electrochemical phenomena was developed. The accuracy of the digital simulation is discussed by comparing with the known solutions. Applying this program to the linear sweep voltammetry at a planar electrode for the electrode reaction, 0 + ne${\to}$R, the accurate current functions for the reversible and totally irreversible charge transfer systems were obtained. Comparing these current functions with the simulated voltammograms for various other values of ${\alpha}$ (0.1 to 1.0) and ${\Lambda}\;(10^{-5}\;to\;10^5)$, the revised zones that are different from those proposed by Matsuda and Ayabe for the reversible and totally irreversible systems are proposed. For ${\alpha}{\ge}$0.1 the reversible zone is in ${\Lambda}{\ge}10^{1.7}$ and the totally irreversible zone is in ${\Lambda}{\le}10^{-1.7}$, where ${\Lambda}=k^{\circ}/ [D_o^{1-{\alpha}}D_R^{\alpha}(nF/RT)v]^{1/2}$.

• Advances in concrete construction
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• 제4권1호
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• pp.37-47
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• 2016

The objective of the present work is to evaluate the influence of two different methods of improving the ductility of Reinforced Concrete Frames and their influence on the full range behavior of the frames with M40 grade of concrete. For this purpose one fourth scale reinforced concrete square frames are experimentally tested subjected to static cyclic loading for three cases and monotonic loading for one case. The parameters are varied as method introducing ductility to the frame viz. (i) by using conventional concrete (ii) adding 1% of steel fibres by volume of concrete at hinging zones (iii) using self-compacting concrete with fibres at hinging zones. The energy absorption by ductile and non-ductile frames has been compared. The behavior of frames tested under cyclic loading have revealed that there is a positive trend in improvement of ductility of frames when fibrous concrete is used along with self-compacting concrete.

• The Korean Journal of Food & Health Convergence
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• 제5권1호
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• pp.13-19
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• 2019

Proximate analysis of Ipomea batatass L. grown in two different locations in Imo State were investigated. Standard soil analytical method was used to determine the physiochemical contents of the two soil sample collected from Mgbidi and Orji Ipomea batatass L. farm land. The soil sand from Ipomea batatass L. root in Orji farm recorded highest percentage value of 75.00% compared to the soil sand Ipomea batatass L. root in Mgbidi farm with 27.00% value. The percentage value of silt was different as the soil Ipomea batatass L. root in Mgbidi farm had high value of 29.40% while soil silt of Ipomea batatass L. root in Orji farm had 13.40%. The soil clay, pH, Phosphorus and Nitrogen from Ipomea batatass L. root in Mgbidi farm recorded highest percentage value of 43.60%, 5.7, 23.20 and 0.35 compared to the soil sand Ipomea root in Orji farm with 11.60%, 5.4, 16.70 and 0.09 value respectively. Ca, Mg, K, and Na analyzed followed the same trend as the soil from Ipomea root in Mgbidi farm had high percentage value of Ca (10.00), Mg (1.60), K (0.54) and Na (0.43) respectively. The systematic study of physiochemical of the Ipomea soils could help in understanding the nutritional composition, the basic characteristics of the soils and the constraints associated with the management of the soils from the two locations.