• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1441-1446
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• 2009

Numerical analysis is a powerful method in evaluating the soil-pile-structure interaction under the dynamic loading, and this approach has been applied to the practical area due to the development of computer technology. Finite Difference Method, one of the most popular numerical methods, is sensitive to the shape and the number of mesh. However, the trial and error approach is conducted to obtain the accurate results and the reasonable simulation time because of the lack of researches about mesh size and the number. In this study, FLAC 3D v3.1 program(FDM) is used to simulate the dynamic pile model tests, and the numerical results are compared with the 1G shaking table tests results. With the different size and shape of mesh, the responses of pile behavior and the simulation time are estimated, and the optimum mesh sizes in dynamic analysis of single pile is studied.

• Journal of the Ergonomics Society of Korea
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• v.31 no.2
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• pp.389-396
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• 2012

Objective: The aim of this study is to design an auto showering system regarding bed type for old people or bedridden patients. Background: The rapid growth concerning the aging population leads to an increase in elderly bedridden patients living in senior care centers and hospitals where care givers have difficulty bathing older people with limited mobility. Method: In this study, a showering equipment for experiment was based on anthropometric and researching existing products. The nozzle position was optimized by showering tests and simulations using showering equipment. Results: The problems regarding the existing products were analyzed and the nozzle position was optimized through showering tests. The number, position, and spraying angle of the nozzle were optimized through showering simulations. The automatic showering system concerning bed type was designed by considering their results. Conclusion: When designing an automatic showering system, the most important design element involves determining the position of nozzle and angle of water injection and the number of nozzles. The system was developed by applying the results through user centered-research. Application: The user centered-research for developing products was applied directly in order to develop automatic baths, showering products etc. Furthermore, it was also available to be applied towards senior friendly products.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.551-561
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• 2006

Incheon bridge project is to construct total 12km long bridges on the sea consist of 800m span length cable stayed bridge, approach bridge and viaduct bridge based on LRFD design specification. To design pile foundations by RCD of each bridge unit, total 4 number of preliminary full scale pile load tests with Osterberg cell method were carried out on the piles for testing. The test load was planned to more than the expected design ultimate capacity and about 29,000tons maximum load was recorded. From the interpretation of test results, design parameters are evaluated and applied to the design. Preliminary pile load test plan and detailed execution of pile load tests are introduced and summarized. The resistance factors are presented for pile design of Incheon Bridge Project in LRFD considering variation of ground conditions and number of test piles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1099-1102
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• 2017

High frequency signals are analyzed which are measured at the inlet / outlet pipeline and pump casing during cavitation tests of the fuel pump for the liquid rocket engine. RMS values of each data are shown according to the cavitation number and compared with those of the LOx pump tests and the impact of the cavitation instability is also explored. Analogies about the cavitation number are confirmed between high frequency data of both pumps. In addition, the cavitation instability is found in all the signals and has an affect on the outlet pressure pulsation of the fuel pump.

• Toxicological Research
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• v.17 no.3
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• pp.235-239
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• 2001

CJ-50005 is an inactivated whole virus vaccine derived from hepatitis A virus (HM175) grown in human MRC-5 diploid fibroblasts cell culture. In order to evaluate the mutagenic potential of CJ-50005, : 3 sets of mutagenicity tests were performed. In the reverse mutation test wing Salmonella typhimurium TA1535, TA1 537, TA98, TA100 and TA102, CJ-50005 did not increase the number of revertants at any concentration tested in this study (2.8, 1.4, 0.7, 0.35 and 0.175 $\mu\textrm{g}$/plate). CJ-50005, at concentration of 2.8, 1.4 and 0.7 $\mu\textrm{g}$/ml, did not increase the number of cells having structural or numerical chromosome aberration in cytogenic test using Chinese Hamster Lung cells. In mouse micronucleus test, no significant increase in the occurrence of micronucleated polychromatic erythrocytes was observed in ICR male and female mice intraperitoneally administered with CJ-50005 at the doses of 25, 12.5 and 6.25 $\mu\textrm{g}$/kg. These results indicate that CJ-50005 has no mutagenic potential in these in vitro and in vivo system.

• Phonetics and Speech Sciences
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• v.5 no.3
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• pp.63-69
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• 2013

The purpose of this study was to evaluate the maximum and optimal listening speed of Korean TTS for the blind. Five blind participants took part in this study. The instruments used in this study were 17 sentence sets (2 sets for an excercise, 10 sets for a repeated test, and 5 sets for a random test), with short meaningful sentences (the same sentences for the repeated test, different sentences for the random test) with 15 differentiated speeds (Range=0.8-3.6, SD=0.2). Each participant's maximum and quickest listening speeds were calculated by objective recall accuracy (determined by the number of correctly recalled syllables/the total number of syllables in a sentence X 100) and subjective recall accuracy (recall accuracy judged by each participant's subjective evaluation). The results showed that the participants' recall accuracy had a tendency to increase as the TTS speed decreased. Participants' subjective recall accuracy was higher than objective recall accuracy in the repeated tests and vice versa in the random tests. The results also revealed that the participants' sentence familiarity had an influence on their Korean TTS listening speed.

• Wind and Structures
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• v.25 no.4
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• pp.397-413
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• 2017

When bridges are constructed with lower heights from the ground, the formed channel between the deck and the ground will inevitably hinder or accelerate the air flow. This in turn will have an impact on the aerodynamic forces on the deck, which may result in unexpected wind-induced responses of bridges. This phenomenon can be referred to "ground effects." So far, no systematic studies into ground effects on the wind-induced responses of closed box girders have been performed. In this paper, wind tunnel tests have been adopted to study the ground effects on the aerodynamic force coefficients and the wind-induced responses of a closed box girder. In correlation with the heights from the ground in two ground roughness, the aerodynamic force coefficients, the Strouhal number ($S_t$), the vortex-induced vibration (VIV) lock-in phenomena over a range of wind velocities, the VIV maximum amplitudes, the system torsional damping ratio, the flutter derivatives, the critical flutter wind speeds and their variation laws correlated with the heights from the ground of a closed box girder have been presented through wind tunnel tests. The outcomes show that the ground effects make the vortex-induced phenomena occur in advance and adversely affect the flutter stability.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.4
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• pp.403-411
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• 2012

This study presents the nano-sized particle emission characteristics from a small turbocharged common rail diesel engine applicable to prime and auxiliary machines on marine vessels. The experiments were conducted under dynamic engine operating conditions, such as steady-state, cold start, and transient conditions. The particle number and size distributions were analyzed with a high resolution PM analyzer. The diesel oxidation catalyst (DOC) had an insignificant effect on the reduction in particle number, but particle number emissions were drastically reduced by 3 to 4 orders of magnitude downstream of the diesel particulate filter (DPF) at various steady conditions. Under high speed and load conditions, the particle filtering efficiency was decreased by the partial combustion of trapped particles inside the DPF because of the high exhaust temperature caused by the increased particle number concentration. Retarded fuel injection timing and higher EGR rates led to increased particle number emissions. As the temperature inside the DPF increased from $25^{\circ}C$ to $300^{\circ}C$, the peak particle number level was reduced by 70% compared to cold start conditions. High levels of nucleation mode particle generation were found in the deceleration phases during the transient tests.

• Steel and Composite Structures
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• v.46 no.4
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• pp.451-469
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• 2023

The use of precast hollow-core slabs (PCHCS) in civil construction has been increasing due to the speed of execution and reduction in the weight of flooring systems. However, in the literature there are no studies that present a finite element model (FEM) to predict the load-slip relationship behavior of pushout tests, considering headed stud shear connector and PCHCS placed at the upper flange of the downstand steel profile. Thus, the present paper aims to develop a FEM, which is based on tests to fill this gap. For this task, geometrical non-linear analyses are carried out in the ABAQUS software. The FEM is calibrated by sensitivity analyses, considering different types of analysis, the friction coefficient at the steel-concrete interface, as well as the constitutive model of the headed stud shear connector. Subsequently, a parametric study is performed to assess the influence of the number of connector lines, type of filling and height of the PCHCS. The results are compared with analytical models that predict the headed stud resistance. In total, 158 finite element models are processed. It was concluded that the dynamic implicit analysis (quasi-static) showed better convergence of the equilibrium trajectory when compared to the static analysis, such as arc-length method. The friction coefficient value of 0.5 was indicated to predict the load-slip relationship behavior of all models investigated. The headed stud shear connector rupture was verified for the constitutive model capable of representing the fracture in the stress-strain relationship. Regarding the number of connector lines, there was an average increase of 108% in the resistance of the structure for models with two lines of connectors compared to the use of only one. The type of filling of the hollow core slab that presented the best results was the partial filling. Finally, the greater the height of the PCHCS, the greater the resistance of the headed stud.

• Journal of Korea Association of Health Promotion
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• v.4 no.1
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• pp.125-131
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• 2006

Background: Inadequate samples make laboratory tests delay cause errors, which will deteriorate the quality of the tests. Therefore, adequate samples are essential for reliable test result. To reduce the inadequate samples, they should to analyze problems and seek a way of improvement through CQI (Continuous Quality Improvement) activity. This will minimize errors during the test and produce a fast and accurate result. Eventrally, the qualily of entire test may be improved, and as a result, a good quality of medical care service may be provided. Methods: At first, inappropriate testing items were collected. Then, generating fctors and problems were investigated and analyzed in each case, In addition, the category with higher frequency wes primarily supervised. In consegalnce, a reduction of are dustion of improper testing sample was oxpected through continuous education and CQI activity. Conclusion : At the beginning of CQI activitv, the number of inadequate testing sample was of 8,591 total samples, which gives the frequency of 0.72%. As CQI activity was carried out the number of improper testing sample reduced to 58 out of 11,415 cases, which yields the frequency of 0,51%. One may notice the difference 0.2%. Among the inadequate sample(blood), there was a high frequency of hemolysis; thus, more of CQI activity is required for this specific matter. Because the occurrence of inadequate testing affects the clinical outcomes, it is extremely important that one manages each step of the procedure in collecting samples and mamtaines the quality of entire tests.