• Journal of the Korean Geophysical Society
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• v.2 no.2
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• pp.123-134
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• 1999

Magnetotelluric responses may be affected by strong anisotropy of the high-conductivity layers (HCL) in the upper mantle or lower crust. We have studied two-dimensional anisotropy MT modelling to examine the effect of high anisotropic media. Electrical properties of a homogeneous anisotropic body are defined by a symmetric conductivity tensor and the problem is described by coupled diffusion equation in the frequency domain. In two-dimensional anisotropic environments, diagonal elements of the impedance tensor have higher values than those in isotropic environments. In some cases, TM mode phases reach more than 90°and apparent resistivities decrease for some frequency range because of telluric distortion. GB decomposition may be used to recover regional responses, but can be affected by the regional anisotropic effect. Considering these results, BC87 dataset was interpreted with a modified anisotropic model.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.6
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• pp.33-39
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• 2007

The seismic source parameters of the Uljin earthquake on 29 May 2004, including focal depth, focal mechanism, magnitude, and moment tensor elements for source characteristics, are analysed using moment tensor seismic source inversion. The Green‘s function for 3 crust models representing the southern Korean Peninsula are used. Also 3 kinds of epicenters are used to find optimum solution for seismic source parameters. Results show that seismic source parameters have a little dependency of azimuthal distribution and epicentral distances of seismic stations. Final results show that the event, considering 6 moment tensor elements, is caused by the typical reverse fault with nearly NS strike. The focal mechanism implies that the tectonic force around epicenter area currently has compressive environment, with nearly EW principal axis. The focal depth is estimated to be about 12km. The resultant focal mechanism show fairly good agreement to those of other studies. However, focal depth is much different from that of other studies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1603-1611
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• 2010

The comparative study of regression-model-based approximate optimization techniques used in the strength design of an automotive knuckle component that will be under bump and brake loading conditions is carried out. The design problem is formulated such that the cross-sectional sizing variables are determined by minimizing the weight of the knuckle component that is subjected to stresses, deformations, and vibration frequency constraints. The techniques used in the comparative study are sequential approximate optimization (SAO), sequential two-point diagonal quadratic approximate optimization (STDQAO), and approximate optimization based on enhanced moving least squares method (MLSM), such as CF (constraint feasible)-MLSM and Post-MLSM. Commercial process integration and design optimization (PIDO) tools are utilized for the application of SAO and STDQAO. The enhanced MLSM-based approximate optimization techniques are newly developed to ensure constraint feasibility. The results of the approximate optimization techniques are compared with those of actual non-approximate optimization to evaluate their numerical performances.

• Earthquakes and Structures
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• v.8 no.3
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• pp.555-572
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• 2015

This paper presents an experimental study of three two-dimensional (2D/planar) steel reinforced concrete (SRC) T-shaped column-RC beam hybrid joints and six 3D SRC T-shaped column-steel beam hybrid joints under low cyclic reversed loads. Considering different categories of steel configuration types in column cross section and horizontal loading angles for the specimens were selected, and a reliable structural testing system for the spatial loading was employed in the tests. The load-displacement curves, carrying capacity, energy dissipation capacity, ductility and deformation characteristics of the test subassemblies were analyzed. Especially, the seismic performance discrepancies between planar hybrid joints and 3D hybrid joints were intensively compared. The failure modes for planar loading and spatial loading observed in the tests showed that the shear-diagonal compressive failure was the dominating failure mode for all the specimens. In addition, the 3D hybrid joints illustrated plumper hysteretic loops for the columns configured with solid-web steel, but a little more pinched hysteretic loops for the columns configured with T-shaped steel or channel-shaped steel, better energy dissipation capacity & ductility, and larger interlayer deformation capacity than those of the planar hybrid joints. Furthermore, it was revealed that the hysteretic loops for the specimens under $45^{\circ}$ loading angle are generally plumper than those for the specimens under $30^{\circ}$ loading angle. Finally, the effects of steel configuration type and loading angle on the seismic damage for the specimens were analyzed by means of the Park-Ang model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3007-3013
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• 2014

The objectives of this study was to evaluate the validity of 3D digital models made from blue LED dental scanner. Twenty same cases of stone models and 3d digital models were manufactured for this study. Intercanine distance, intermolar distance, two dental arch lengths(right, left) and two diagonal of dental arch lengths(right, left) were measured for evaluation of validity. The nonparametric Wilcoxon rank sum test was used for statistical analysis (${\alpha}$=0.05). Although stone models showed larger than digital models in all measured distances(p<0.05), none exceeded the clinically acceptable range.

• Journal of dental hygiene science
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• v.15 no.4
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• pp.393-398
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• 2015

One of the most critical causes in determining the clinical outcomes of dental prostheses is the validity of models. However, studies that evaluated validity of digital models are few. The objectives of this study were to evaluate validity of edentulous digital models for full denture fabrication. Twenty stone models (edentulous model) were manufactured and scanned by dental blue light emitting diode scanner. Twenty digital models were manufactured. Six linear distances (inter-canine distance, inter-molar distance, two dental arch lengths (right, left), two diagonal of dental arch lengths (right, left) were measured for validity evaluation. The measurements of distances of stone models were used by digital vernier caliper and digital models were used by computer program. The mean${\pm}$deviations values of six distances were calculated. The means were compared by the Mann Whitney U test (${\alpha}=0.05$). All statistical analysis were performed using IBM SPSS Statistics ver. 20.0. Although digital models were smaller than stone models in six distances, there were no significant differences (p>0.05) and non exceeded the clinical acceptable range. The edentulous digital models for full denture fabrication can be considered clinically acceptable.

• Journal of the Korea Concrete Institute
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• v.15 no.5
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• pp.689-696
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• 2003

Recently, Appendix A of ACI 318∼02 Code introduced the Strut-and-Tie Model(STM) procedure in shear design of deep flexural members. The STM procedure is widely used in the design of concrete regions where the distribution of longitudinal strains is significantly nonlinear, such as deep beams, beams with large openings, corbels, and dapped-end beams. Experimental study included five high-strength reinforced concrete deep beams with different detailing schemes for the horizontal and vertical reinforcement. The specimens were designed as simply supported beams subjected to concentrated loads on the top face and supported on the bottom face. At failure, all specimen exhibited primary diagonal crack running from the support region to the point load. Specimens which had mechanical anchorages(terminators) gives better representation of the load-carrying mechanism than the specimen had standard 90-degree anchorage at failure in deep flexural members. Based on the test results, shear design procedures contained in the ACI 318-99 Code, Appendix A of the ACI 318-02 Code, CSA A23.3-94 Code and CIRIA Guide-2 were evaluated. The Shear design of ACI 318-99 Code, Appendix A of the ACI 318-02 Code and CIRIA Guide-2 shown to be conservative predictions from 10% to 36% in the shear strength of the single-span deep beam which was tested. ACI 318-99 Code was the lowest standard deviation.

• Korea journal of population studies
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• v.20 no.1
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• pp.97-128
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• 1997

This paper was set out to study the structure of the career occupational mobility in the early and rapid phase of industrialization in Korea. By analyzing the individual life histories regarding occupational mobility and achievement, I propose a model of yearly career mobility of Korean men and Women during the period of 30 years between 1954 and 1983. With the occupational classification scheme of 5 groups - Upper Nonmanual, Lower Nonmanual, Self Employed, Manual, Farm - the mobility pattern in the person-year mobility table analyzed can be characterized primarily by the strong influence of immobility. The degree of immobility, however, is different by the occupational groups. The absolute amount of immobility can be summarized as being U-shaped. Overall, the pattern of mobility can be explained best by the concept of occupational distance. I then propose a model of relative career occupational mobility pattern that combines the conceptual and theoretical basis and the methodological rigor. The model is based on the notion of the reproduction of inequality, the labor market context, and the life history perspective. The model encompasses the 6 conceptual explanatory factors such as persistence effect, ceiling effect, traditional sector effect, nonmanual occupation effect, alternative mobility channel effect, and occupational distance effect, as well as the effects of both origin and destination occupations. The relative pattern of career mobiliity in Korea can be characterized by the following six findings. First, the persistence effect on the diagonal cells of the mobility table is dominant. Second, a clear evidence of the negative effect of occupational distance between nonmanual occupations and manual and farm occupations is found. Third, the out-mobility from farming took place regardless of the destination occupations. Fourth, the internal mobility within the nonmanual occupation block is high and bi-directional, and is exclusive against other occupations. Fifth, the 'self employed' occupation is serving a peculiar function in both inflow and outflow pattern. Last, the relative pattern of career occupation mobility is asymmetrical in terms of the upward and downward mobility.

• Korea journal of population studies
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• v.10 no.1
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• pp.28-38
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• 1987

This paper was set out to study the structure of the career occupational mobility in the early and rapid phase of industrialization in Korea. By analyzing the individual life histories regarding occupational mobility and achievement, I propose a model of yearly career mobility of Korean men and Women during the period of 30 years between 1954 and 1983. With the occupational classification scheme of 5 groups - Upper Nonmanual, Lower Nonmanual, Self Employed, Manual, Farm - the mobility pattern in the person-year mobility table analyzed can be characterized primarily by the strong influence of immobility. The degree of immobility, however, is different by the occupational groups. The absolute amount of immobility can be summarized as being U-shaped. Overall, the pattern of mobility can be explained best by the concept of occupational distance. I then propose a model of relative career occupational mobility pattern that combines the conceptual and theoretical basis and the methodological rigor. The model is based on the notion of the reproduction of inequality, the labor market context, and the life history perspective. The model encompasses the 6 conceptual explanatory factors such as persistence effect, ceiling effect, traditional sector effect, nonmanual occupation effect, alternative mobility channel effect, and occupational distance effect, as well as the effects of both origin and destination occupations. The relative pattern of career mobiliity in Korea can be characterized by the following six findings. First, the persistence effect on the diagonal cells of the mobility table is dominant. Second, a clear evidence of the negative effect of occupational distance between nonmanual occupations and manual and farm occupations is found. Third, the out-mobility from farming took place regardless of the destination occupations. Fourth, the internal mobility within the nonmanual occupation block is high and bi-directional, and is exclusive against other occupations. Fifth, the 'self employed' occupation is serving a peculiar function in both inflow and outflow pattern. Last, the relative pattern of career occupation mobility is asymmetrical in terms of the upward and downward mobility.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.143-150
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• 2014

To avoid abrupt torsional failure due to concrete crushing before yielding of torsional reinforcement and control the diagonal crack width, design codes specify the limitations on the yield strength of torsional reinforcement of RC members. In 2012, Korean Concrete Institute design code increased the allowable maximum yield strength of torsional reinforcement from 400 MPa to 500 MPa based on the analytical and experimental research results. Although there are many studies regarding the shear behavior of RC members with high strength stirrups, limited studies of the RC members regarding the yield strength of torsional reinforcement are available. In this study, twelve RC beams having different yield strength of torsional reinforcement and compressive strength of concrete were tested. The experimental test results indicated that the torsional failure modes of RC beams were influenced by the yield strength of torsional reinforcement and the compressive strength of concrete. The test beams with normal strength torsional reinforcement showed torsional tension failure, while the test beams with high strength torsional reinforcement greater than 480 MPa showed torsional compression failure. Therefore, additional analytical and experimental works on the RC members subjected to torsion, especially the beams with high strength torsional reinforcement, are needed to find an allowable maximum yield strength of torsional reinforcement.