• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.109-111
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• 2009

In this paper, we discuss how to design 2-wheeled mobile robot hard wares as reasonable and practical as possible. A segway type mobile robot consists of 2 wheels only, placed in parallel rather than horizon. 2-wheeled mobile robots make you overcome high cost and time consuming maintenance procedures of the robot by reducing the number of robot hardwares. The most challenging thing in a 2-wheeled mobile robot that has many more valid virtues than the traditional mobile robots is to make it balance itself whenever it stands still or goes forward. But balancing itself is not an easy matter and there are many researches and experiments on this issue. When researchers test theories on 2-wheeled mobile robots to improve its self balancing performance, they should consider how to design hard wares of that mobile robot. No matter how great those new theories are, if a testbed for those theories is not suitable, performance output would be poor and meaningless. In this point of view, to design a proper 2-wheeled mobile robot as a testbed is a very important issue with development of new theories. So we define 4 guide lines to design segway type mobile robots reasonably; about motor, battery, and MCU selection and shock-proof design with robust motor setting.

• Korean Journal of Occupational Health Nursing
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• v.17 no.2
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• pp.155-165
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• 2008

Purpose: The purpose of this study was to investigate the condition, recognition of breast feeding of 273 nurses. Method: Data was collected using a structured questionnaire form April to June 2007. The subjects were 273 nurses in Kyunggido. The data analysis was done with descriptive statistics, $x^2$-test procedures using SPSS/WIN 12.0 PC. Result: There are 23.9% of child day care center, 5.2% of rest room for women, 16.8% of breast feeding room in workplace. Rate of breast-feeding practice was 78.4% of nurses. The reasons why they could not perform the breast-feeding include mother's job(45.4%), lacking breast milk(25.8%). The characteristics of nurses found to be related breast-feeding include age, number of employers. Conclusion: The results showed that the rest supports of the work environment was insufficient to perform breast-feeding in the workplace. These results suggest that nursing intervention for employed mother's breast-feeding practice behavior promotion should focus on characteristics influencing factors on workplace. Also, efficient breast-feeding education program for employed mothers should be developed by continuous qualitative researches based on breast-feeding experiences of employed mothers.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.201-208
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• 1993

The emergence of the Global Positioning System(GPS) with its benefits of speed and economy now offers an opportunity to analyse, strengthen, densify and constitute the control network, in addition to providing mapping, cadastral and engineering control under the unfavorable conditions. This research aims at the using of GPS compared to conventional geodetic positioning techniques in Korean primary control networks. A GPS test network of 10km baselines, which is measured and analysed by Wild GPS-System 200, are compared to the distances from EDM and official coordinates, and relative GPS heights are transformed to the height differences on the mean sea level. The results of this study confirms that using GPS merely as a new type of instrument is the most powerful method for the densification of the control points retaining existing networks and existing computational procedures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.409-416
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• 2009

Standard procedures for a fracture toughness testing require very severe restrictions for the specimen geometry to eliminate a size effect on the measured properties. Therefore, the used standard fracture toughness data results in the integrity assessment being irrationally conservative. However, a realistic fracture in general structures, such as in nuclear power plants, may develop under the low constraint condition of a large scale yielding with a shallow surface crack. In this paper, cleavage fracture toughness tests have been made on side-grooved PCVN (precracked charpy V-notch) type specimens (10 by 10 by 55 mm) with various crack depths. The constraint effects on the crack depth ratios were evaluated quantitatively by the developed scaling method using the 3-D finite element method. After the fracture toughness correction from scaling model, the statistical size effects were also corrected according to the standard ASTM E 1921 procedure. The results were evaluated through a comparison with the $T_0$ of the standard CT specimen. The corrected $T_0$ for all of the PCVN specimens showed a good agreement to within $5.4^{\circ}C$ regardless of the crack depth, while the averaged PCVN $T_0$ was $13.4^{\circ}C$ higher than the real CT test results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.5 s.236
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• pp.568-576
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• 2005

A 3-D finite element model combined with a volume tracking method is presented in this work to simulate the mold filling for casting processes. Especially, the analysis involves an adaptive grid method that is created under a criterion of element categorization of filling states and locations in the total region at each time step. By using an adaptive grid wherein the elements, finer than those in internal and external regions, are distributed at the surface region through refinement and coarsening procedures, a more efficient analysis of transient fluid flow with free surface is achieved. Adaptive grid based on VOF method is developed in tetrahedral element system. Through a 3-D analysis of the benchmark test of the casting process, the efficiency of the proposed adaptive grid method is verified. Developed FE code is applied to a typical industrial part of the casting process such as aluminum road wheel.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.19-20
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• 2006

The emission of particulate matter from marine diesel engines is already restricted by regional regulations in some countries, and IMO has been preparing the regulation for particulate matter from 53rd MEPC. But confusingly, the gravimetric PM measurement methods and procedures are not established clearly yet. On the other hand, smoke measurement method is set clearly, and it can also indicate PM, though it is not direct gravimetric method. As the preparing step for regulations about PM, we measured the smote density of exhaust emission from the marine four-stroke diesel engines operated in constant speed and various load steps on the test-bed, using the filter-type smoke measuring instrument. As a result, we understood the omission characteristics of smoke from the engines. Additionally, to obtain the objective reliability of our measurement data, we carried out experimental studies about various measuring parameters that could affect the smoke density.

• Computers and Concrete
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• v.19 no.5
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• pp.545-553
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• 2017

In the authors' previous study, an axial force-flexural moment (P-M) interaction curve model was proposed to evaluate fire-resisting performances of reinforced concrete (RC) column members. The proposed method appeared to properly consider the axial and flexural strength degradations including the secondary moment effects in RC columns due to fire damage. However, the detailed P-M interaction curve model proposed in the authors' previous study requires somewhat complex computational procedures and iterative calculations, which makes it difficult to be used for practical design in its current form. Thus, the aim of this study was to develop a simplified P-M interaction curve model of RC columns exposed to fire considering the effects of fire damage on the material performances and magnitudes of secondary moments. The simplified P-M interaction model proposed in this study was verified using 66 column fire test results collected from literature, and the verification results showed that the proposed simplified method can provide an adequate analysis accuracy of the failure loads and fire-resisting times of the RC column specimens.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.3
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• pp.41-52
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• 2002

In the companion paper, nonlinear finite element analysis procedures are presented for the seismic damage evaluation of RC bridge piers. This paper defines a damage index based on the predicted hysteretic behavior of a RC bridge pier. Damage indices aim to provide a means of quantifying numerically the damage in RC bridge piers sustained under earthquake loading. The proposed numerical method is applied to RC bridge piers tested by other, and compared to existing damage indices. The proposed numerical method gives a realistic prediction of damage throughout the loading cycles for several test specimens investigated.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.4
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• pp.1-10
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• 1999

Free-field ground motion during earthquake is significantly affected by the local site conditions and it is essential for the seismic design to perform the site specific ground response analysis. In this paper, the procedures of site specific ground response analysis were suggested based on the Korean seismic guideline and the review of state of the art technologies. The concept of ground response analysis was introduced, and the techniques of obtaining soil data for one dimensional equivalent linear analysis which include site investigation planning, field and laboratory testing techniques, deformational characteristics of soils at small to large strains, and site characterization techniques combining field and laboratory test results, were suggested. Finally, the case study was performed at Inchon area following the suggested procedure.

• PNF and Movement
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• v.15 no.3
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• pp.281-290
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• 2017

Purpose: The purpose of this study was to examine the effect of an 8-week competitive exercise program on physical fitness, psychological variables, and video-game playtime in game-addicted adolescents. Methods: All subjects were screened by a game behavior diagnosis scale questionnaire, and a total of 7 game-addicted, male adolescents ($16{\pm}2$ yrs of age) participated in the study. All subjects were informed of the study's purpose, procedures, and risks, and a consent form was obtained from each subject. The 8-week soccer and basketball exercise program included twice-weekly sessions of 120 minutes per session. All data were presented as $mean{\pm}SE$, and the variables were analyzed with a paired t-test. Results: Following the 8-week intervention, cardiovascular endurance and grip strength were significantly increased (approximately 17 and 7%, respectively [p<0.05]). Although there was no statistical significance on flexibility, vertical jump, and zigzag-run, all variables showed an increasing tendency. Anxiety levels changed from a mild anxiety state to a normal state, and depression levels also altered from moderate to a normal state. The video-game playtime was reduced about 20% during weekends and vacation periods. Conclusion: Given these combined results, 8 weeks of regular participation in competitive exercise (soccer/basketball) may contribute to positive effects on physical fitness, psychological variables, and video-game playtime in computer-game addicted adolescents.