• Earthquakes and Structures
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• v.12 no.6
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• pp.643-652
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• 2017

One of the methods to strengthen the structures against the seismic lateral loading is the employment of the composite columns. A concrete-filled tube (CFT) has the cumulative advantages of steel and concrete. Concrete-filled steel tube columns have been widely used in the moment-resisting frame (MRF) structures, located in both non-seismic zones and high-risk seismic zones. In this paper, the results of studies on two important seismic parameters of ductility and the response modification factor (RMF) of the MRFs with CFT columns are submitted. While the studies are carried out, the effects of span length-story height ratio, the strength of materials and seismic behavior of MRFs are considered. In this regard, the ductility, RMF and the strength of 36 models of the steel MRFs with CFTs are analyzed. The fiber plastic hinges numerical simulation and pushover analysis method are used in the calculations. Based on the obtained results, the RMFs suitable for the 5-, 10- and 15- story frames are proposed.

• Korean Journal of Health Education and Promotion
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• v.31 no.4
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• pp.37-49
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• 2014

Objectives: The aim of this study was to evaluate the effects of a lifestyle modification program for Korean adults with cardiovascular disease risk factors on their health behaviors and health status. Methods: A total of 448 adults with abdominal obesity and additional cardiovascular disease risk factors(high blood pressure, low HDL-cholesterol, high triglyceride or high blood glucose) were randomly assigned to either an intensive intervention group (IIG, n=216) or a minimal intervention group(MIG, n=232). Participants in the IIG received lifestyle modification program which consisted of health counseling with nutrition assessment, health booklet and health diary, while those in MIG received minimal information. Results: The participants in the IIG significantly improved dietary habits(p<.05), retrained eating(p<.001), external eating(p<.01) behaviors, leisure time physical activity(p<.05), dietary self-efficacy(p<.01), exercise self-efficacy(p<.01) and MetS score(p<.001) after 3 months. In addition, the participants in the IIG showed more improvement in dietary habits(p<.05) compared with those in the MIG. Conclusion: The lifestyle modification program was effective in improving some health behaviors, behavioral determinants and cardiovascular risk factors for a short term.

• Journal of Powder Materials
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• v.18 no.3
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• pp.269-276
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• 2011

The synthesis behavior of nanoporous silica aerogel in the macroporous ceramic structure was observed using TEOS as a source material and glycerol as a dry control chemical additive (DCCA). Silica aerogel in the macroporous ceramic structure was synthesized via sono-gel process using hexamethyldiazane (HMDS) as a modification agent and n-hexane as a main solvent. The wet gel with a modified surface was dried at $105^{\circ}C$ under ambient pressure. The addition of glycerol appears to give the wet gel a more homogeneous microstructure. However, glycerol also retarded the rate of surface modification and solvent exchange. Silica aerogel completely filled the macroporous ceramic structure without defect in the condition of surface modification (20% HMDS/nhexane at 36hr).

• Speech Sciences
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• v.7 no.3
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• pp.229-247
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• 2000

The purpose of this study is to examine the improvement effect of articulation of the fricative consonant /s/(ㅅ), when applying the Articulation Modification Program (AMP) to hearing disordered students. Three hearing disordered students were selected for this study by the consonant picture and Korean Articulation Sentence tests. They have no defect in their emotion, behavior and sight. This program applied the multiple baseline design across subjects to examine the improvement effect of articulation of fricative consonant /s/(ㅅ). Also I designed th$\sim$s program with an advanced pre-test and post-test in order to research the improvement difference of articulation by articulation position and language unit. It was executed 32 sessions over three months, four sessions a week, one session taking forty minutes. The results according to the study subject are as follow; First, as result of AMP, articulation of all students was developed after applying this program. Second, as result of AMP, articulation in fore-word was one-hundred percent efficiency and articulation in middle-word was 97.7% efficiency by position. Third, as result of AMP, articulation in the word reached 98.7% efficiency, in phrase 97.7% efficiency, in the sentence 97.7% efficiency and in the story was 98.3% efficiency by language unit.

• Journal of Korea Foundry Society
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• v.34 no.5
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• pp.156-161
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• 2014

This study is focused on the effect of $Al_2Ca$ as a modifier on eutectic Si modification of A356 alloy. Microstructural observation was carried out for as-cast, as-solution treated and as-aged samples. Solution treatment and aging were performed for 2, 4, 6 and 10 hrs at $540^{\circ}C$ and $170^{\circ}C$, respectively. Although A356 alloy, which $Al_2Ca$ was added, has no significant difference in as-cast phases with normal A356 alloys, it shows much more modified eutectic Si, grain refinement and improved tensile property both in as-cast and as-heat treated conditions. TGA result shows that $Al_2Ca$ added A356 alloy has a certain improvement in oxidation resistance.

• Earthquakes and Structures
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• v.20 no.4
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• pp.389-403
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• 2021

Skewed bridges, being irregular structures with complicated dynamic behavior, are more susceptible to earthquake damage. Reliable seismic-resistant design of skewed bridges can be achieved by accurate determination of nonlinear seismic demands. However, the effect of geometric characteristics on the response modification factor (R-factor) is not accounted for in bridge design practices. This study attempts to investigate the effects of changes in the number of spans, skew angle and bearing stiffness on R-factor values and to assess the seismic fragility of skewed bridges. Results indicated that changes in the skew angle had no significant effect on R-factor values which were in consonance with code-prescribed R values. Also, unlike the increase in the number of spans that resulted in a decrease in the R-factor, the increase in bearing stiffness led to higher R-factor values. Findings of the fragility analysis implied that although the increase in the number of spans, as well as the increase in the skew angle, led to a higher failure probability, greater values of bearing stiffness reduced the collapse probability. For practicing design engineers, it is recommended that maximum demands on substructure elements to be calculated when the excitation angle is applied along the principal axes of skewed bridges.

• Journal of the Korean Institute of Telematics and Electronics
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• v.10 no.6
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• pp.62-71
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• 1973

ECAP(Electronic Circuit Analysis Program) is used for analysis of a gyrator network obtained by conventional approach. Thus obtained characteristics of the original network showed the necessity of some improvement. Modification of the network was made through DC Analysis of ECAP for improved behavior of gyrator. by the replacement of resistors in collector circuits with constant current source circuits, thus decreasing the required voltage of collector bias source voltage, and in turn, increasing collector resistances. The modified network was again analized through ECAP AC Analysis. The result justifies the modification of networks and tile utilization of a computer program for network analysis instead of a "breadboard" experiment.xperiment.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.959-964
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• 2001

This study investigates the seismic performance of bearing walls with rectangular sectional shape and specific details of reinforcements developed for 10 to 20-story apartment buildings in Korea. To investigate seismic behavior of structural walls, several specimens were experimented by author and laboratory test results by other researchers were collected and analysed. Structural behaviors of walls were evaluated by means of ductility, deformation, and strength capacities. For this purpose, thirty six specimens having different Properties such as aspect ratios and details were considered. Based on the results of this study, deformability of the walls with specific details is discussed. Also this study compares the response modification factor(R) for the bearing wall systems in seismic design provisions between Korea and United States.

• Journal of Industrial Technology
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• v.19
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• pp.361-368
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• 1999

The Nelder-Mead simplex algorithm has become on of the most widely used methods for nonlinear unconstrained optimization, since 1965. Recently, this algorithm has been reevaluated and many papers on this algorithm are being published. The MATLAB computer software, highly renown in engineering, also provides the Nelder-Mead algorithm and the Denis-Woods modification with FMINS function. The authors made C++ code of these algorithms and compared with FMINS on the convergence behavior and the exactness of solutions. It shows that MATLAB's FMINS is inferior to author's C++ code. So, FMINS should be corrected for every user.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.201-208
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• 2006

This study lotuses on the seismic behavior of 3-, 9-, and 20-story steel moment resisting frame (MRF) structures designed in accordance with the 2000 International Building Code using different Response Modification factors (R factors) 8, 9, 10, 11, and 12. For a detailed case study, 30 different structures were evaluated for twenty ground motions representing the hazard level which is equal to a 2% probability exceeding in 50 years (2% in 50 years). The results showed that the current R factors provide conservative designs for the 3- and 9-story buildings for the Collapse Prevention performance objective. However, the 20-story buildings designed without using the minimum requirement of spectral acceleration CS prescribed in the IBC 2000 did not satisfy the seismic performance for Collapse Prevention performance.