• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.4 s.74
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• pp.375-387
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• 2006

Different from the previous studies which investigated seismic P-$\Delta$ effect in slender columns though comparison of response spectra according to stability coefficients obtained from the analyses based on the assumed moment-curvature relationship, the axial force and P-$\Delta$ effect in RC columns are investigated on the basis of the layered section method which can effectively consider the changes of stiffness and yield strength due to the application of axial force in RC members. Practical ranges of slenderness and stability coefficient are assumed, and sixty sets of horizontal/vertical earthquake inputs are used in the analysis. From the parametric study, it is noted that the maximum deformation of the slender RC column is hardly affected by P-$\Delta$ effect or vortical earthquake but dominantly affected by the applied axial force. Therefore, it can be concluded that no additional consideration for the P-$\Delta$ effect and vortical earthquake is required in the seismic design of a slender RC column if the axial force effect is taken into account in the analysis and design procedures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.427-434
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• 2017

Recently, awareness of the public about the explosion damage has increased due to the increased risk of terrorism. The criteria for blast-resistance design is not sufficient in Korea, it is necessary to develop blast-resistance design for the stability and safety of building by static analysis of current blast-resistance design. In addition, as the increase of earthquake occurrence necessitates the seismic design, it is studied to judge the blast-resistance performance of members applying seismic design without blast-resistance design. Currently, the general analysis of blast load is to refer to UFC 3-340-02 manual. Blast-resistance performance was studied by applying characteristics of blast load through UFC 3-340-02 manual, beam converted into equivalent SDOF System. It is proved that blast-resistance performance is improved when seismic detail is applied considering the maximum deflection of normal, intermediate, and special moment frames.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.2
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• pp.29-37
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• 2003

In this study, a story-wise distribution of hysteretic energy in steel moment resisting framse(MRF), buckling restrained braced frames(BRBF), and hinge-connected framed structures with buckling restrained braces(HBRBF) subjected to various earthquake ground excitations was investigated. Sixty earthquake ground motions recorded in different soil conditions were used to compute the energy demand in model structure. According to analysis results, the hysteretic energy in MRF and BRBF turned out to be the maximum at the base and monotonically diminishes with increasing height. However the story-wise distribution of hysteretic energy in HBRBF was relatively uniform over the height of the structure. In this case damage is not concentrated in a single story, and therefore it is considered to be more desirable than other systems. The story-wise energy distribution pattern under three different soil types turned out to be approximately the same.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.6
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• pp.37-46
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• 2012

In Korea, most existing school buildings have been constructed with moment frames with un-reinforced infill walls designed only considering gravity loads. Thus, the buildings may not perform satisfactorily during earthquakes expected in Korea. In exterior frames of the building, un-reinforced masonry infill walls with window openings are commonly placed, which may alter the structural behavior of adjacent columns due to the interaction between the wall and column. The objective of this study is to evaluate the seismic performance of existing school buildings according to the procedure specified in ATC 63. Analytical models are proposed to simulate the structural behavior of columns, infill walls and their interaction. The accuracy of the proposed model is verified by comparing the analytical results with the experimental test results for one bay frames with and without infill walls with openings. For seismic performance evaluation, three story buildings are considered as model frames located at sites having different soil conditions ($S_A$, $S_B$, $S_C$, $S_D$, $S_E$) in Korea. It is observed that columns behaves as a short columns governed by shear due to infill masonry walls with openings. The collapse probabilities of the frames under maximum considered earthquake ranges from 62.9 to 99.5 %, which far exceed the allowable value specified in ATC 63.

• Journal of Korea Water Resources Association
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• v.47 no.5
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• pp.469-482
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• 2014

This study developed a Bayesian spatial regional frequency analysis, which aimed to analyze spatial patterns of design rainfall by incorporating geographical information (e.g. latitude, longitude and altitude) and climate characteristics (e.g. annual maximum series) within a Bayesian framework. There are disadvantages to considering geographical characteristics and to increasing uncertainties associated with areal rainfall estimation on the existing regional frequency analysis. In this sense, this study estimated the parameters of Gumbel distribution which is a function of geographical and climate characteristics, and the estimated parameters were spatially interpolated to derive design rainfall over the entire Han-river watershed. The proposed Bayesian spatial regional frequency analysis model showed similar results compared to L-moment based regional frequency analysis, and even better performance in terms of quantifying uncertainty of design rainfall and considering geographical information as a predictor.

• Korean Journal of Community Nutrition
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• v.9 no.4
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• pp.519-527
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• 2004

This study was designed firstly to measure the job satisfaction (JS) levels of personnel engaged in contract food-service management company (CFMC), secondly to compare the job satisfaction levels by personal and company-related characteristics, and thirdly to identify the effects of JS facets on overall job satisfaction. Of 1135 respondents, there were 712 employees in the headquarters and 423 in the branch office. From an analysis on job satisfaction, overall job satisfaction level was 3.22 out of a maximum 5 and the co-worker (3.71) facet of JS was the highest job satisfaction followed by supervision (3.32), work itself (3.26), working condition (3.15), promotion (2.95) and payroll (2.74). In comparison of job satisfaction by personal characteristics, the personnel who were male (p < .01), had associate degrees (p < .01) or long-term careers in foodservice field (p < .05), or were regular employees (p < .01) perceived significantly higher than others for overall JS. In comparison of the job satisfaction by company-related characteristics, overall JS was significant by company scale (p < .01) and by work place (p < .05), but it was not significant by operating group. Finally, on the regression analysis for the effects of JS facets on overall JS, adjusted R2 was 0.534 (p < .001) and all six JS facets, especially payroll, had a positive effect on overall JS significantly (p < .001). Considering that the goal of enterprise on profit-making through customer satisfaction (CS) and the role of personnel on CS at moment of thrust (MOT), the findings confirmed the necessity for continuous internal marketing and human relation management focusing on the lower level of JS facets.

• Journal of the Korean Data and Information Science Society
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• v.27 no.4
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• pp.1001-1012
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• 2016

It is well known that air pollutants exert a bad influence on human health. According to the United Nations Environment Program, 4.3 million people die from carbon monoxide and particulate matter annually from all over the world. Carbon monoxide is a toxic gas that is the most dangerous of the gas consisting of carbon and oxygen. In this paper, we used 1 hour, 6 hours, 12 hours, and 24 hours average carbon monoxide concentration data collected between 2004 and 2013 in Daegu Gyeongbuk area. Parameters of the generalized extreme value distribution were estimated by maximum likelihood estimation and L-moments estimation. An evalution of goodness of fitness also was performed. Since the number of samples were small, L-moment estimation turned out to be suitable for parameter estimation. We also calculated 5 year, 10 year, 20 year, and 40 year return level.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.3
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• pp.295-302
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• 2007

Statement of problem. Fracture of the tooth-colored superstructure material is one of the main prosthetic complications in implant-supported prostheses. Purpose. The purpose of this in vitro study was to compare the fracture strength between the cement-retained implant-supported metal-ceramic crowns and the indirect composite resinveneered metal crowns under the vertical compressive load. Material and methods. Standard implants of external type (AVANA IFR 415 Pre-mount; Osstem Co., Busan, Korea) were embedded in stainless steel blocks perpendicular to their long axis. Customized abutments were fabricated using plastic UCLA abutments (Esthetic plastic cylinder; Osstem Co., Busan, Korea). Thirty standardized copings were cast with non-precious metal (Rexillium III, Pentron, Walling ford, Conn., USA). Copings were divided into two groups of 15 specimens each (n = 15). For Group I specimens, metal-ceramic crowns were fabricated. For Group II specimens, composite resin-veneered (Sinfony, 3M-ESPE, St. Paul, MN, USA) metal crowns (Sinfony-veneered crowns) were fabricated according to manufacturer's instructions. All crowns were temporary cemented and vertically loaded with an Instron universal testing machine (Instron 3366, Instron Corp., Norwood, MA, USA). The maximum load value (N) at the moment of complete failure was recorded and all data were statistically analyzed by independent sample t-test at the significance level of 0.05. The modes of failure were also investigated with visual analysis. Results. The fracture strength of Sinfony-veneered crowns ($2292.7{\pm}576.0N$) was significantly greater than that of metal-ceramic crowns ($1150.6{\pm}268.2N$) (P < 0.05). With regard to the failure mode, Sinfony-veneered crowns exhibited adhesive failure, while metal-ceramic crowns tended to fracture in a manner that resulted in combined failure. Conclusion. Sinfony-veneered crowns demonstrated a significantly higher fracture strength than that of metal-ceramic crowns in cement-retained implant-supported prostheses.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.4
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• pp.251-276
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• 2002

The purpose of this study was to compare and analyze the stress distribution and displacement of the fully bone anchored bridge and implant-supported overdenture in edentulous mandible on certain conditions such as number of implants, different design of superstructure. Three dimensional analysis was used and nine kinds of models designed for this study. FEM models were created using commercial software[$Rhinoceros^{(R)}$ (Ver. 1.0 Robert McNeel & Associates, USA)], and analyze using commercial software [Cosmos/$Works^{TM}$(Ver. 4.0 Structural Research & Analysis Corp., US A)]. A vertical load and $45^{\circ}$ oblique load of 17kgf were applied at the left 1st. molar. The results were as follows : (1) In the group of OVD, the displacement was reduced as increasing the number of fixture under vertical loading but there was no specific difference in Von Mises stress. Under oblique loading, the displacement was same at the vertical loading but Von Mises stress was reduced in order of OVD-3, OVD-4, OVD-2. But, bending moment reduced according to increasing the number of fixture. (2) In the group of FBAB, under vertical and oblique loading, the magnitude of Von Mises stress and displacement reduced according to increasing the number of fixtures. FBAB-4 and FBAB-5 showed similar score and distribution, but FBAB-6 showed lower value relatively. (3) In cantilever design, the maximum displacement reduced under vertical loading but increased under oblique loading. However, von mises stresses on fixtures increased under vertical and oblique loading. (4) In comparing OVD-group with FBAB-group, FBAB showed low magnitude of displacement in respect of oblique loading. However OVD-group was more stable in respect of stress distribution.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.141-144
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• 2008

Deflection in terms of serviceability of reinforced concrete structures is considered as one of significant factor. Domestic concrete specification offers a procedure to evaluate deflection using effective moment of inertia at cracked section, which has been known as Branson's equation in ACI. Branson's equation was derived from statistical analysis of maximum deflection of flexural members, but is somewhat weak in no reflection of bond characteristics between reinforced bars and concrete, such as tension stiffening effect. Therefore, present code creates difference from actual deflection. In this study, experiments about deflection of RC beams was completed to compare domestic standard and Eurocode 2, which calculates deflection considering tension stiffening effect. Four RC beams were built and tested, and initial modulus of elasticity and tensile strength of concrete used in the test was calculated by each design standard.