• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.414-423
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• 2020

Fiber-reinforced polymer (FRP) laminate sheets, which are lightweight with high strength, are commonly used to reinforce concrete structures. The bonding strength is vital in structural design. Therefore, experiments and analytical studies with differing variables (concrete compressive strength and tensile strength, the elastic modulus of concrete and FRP, thickness of concrete and FRP, width of concrete and FRP, bond length, effective bond length, fracture energy, maximum bond stress, maximum slip) have been conducted to obtain an accurate numerical model of the bond strength between an FRP sheet and concrete. Although many models have been proposed, no validated model has emerged that could be used easily in practice. Therefore, this study analyzed the parameters that influence the bond strength that were used in 23 of the proposed models (Khalifa model, Iso model, Maeda model, Chen model, etc.) and compared them to the test results of 188 specimens via the numerical results of each model. As a result, an easy-to-use practical model with a simple and high degree of expression was proposed based on the Iso model combined with the effective bond length model that was proposed by Holzenkӓmpfer.

• Journal of Korean society of Dental Hygiene
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• v.8 no.3
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• pp.115-126
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• 2008

Purpose : The research which sees width for a wide gain and loss is about brush qualitative management of the child about dental hygiene of the child is investigated the brush qualitative actual condition. Methods : The data which is collected used SPSS(Statistical Package for the Social Science) WIN 11.5 programs and analyzed, a frequency and a percentage with analytical technique, in order to grasp the general quality of the investigation object person produced to examine is about the brush quality control actual condition of the children opinion t-test (verification) frequency analyses and $x^2$(Chi-square) verifications, executed. Result : The followings are the findings of this research. First, the children about the reason which wipes this 83.4% the thing protection dental caries answer back, followed in grade and considers the difference which was visible(p<0.001). Second, wipes whether to experience is educated answer back 83.0% was educated, followed in sex and considers the difference which was visible(p<0.05). Third, when 1 time is brush quality of the children doing, in grade and the time when becomes disturbance was, most between 2~3 minutes followed considers the difference which was visible(p<0.01). Fourth, when 1 time is brush quality of the children doing, in grade and the time when becomes disturbance was, most between 2~3 minutes followed considers the difference which was visible(p<0.01). Fifth, when 1 time is brush quality of the children doing, in grade and the time when becomes disturbance was, most between 2~3 minutes followed considers the difference which was visible(p<0.05, p<.001). Sixth, Use duration of the toothbrush the child of most was 3~6 months, according to grade and sex was visible the difference which considers. Conclusion : Are oral healthily of the children is the knowledge which relates with a brush quality and practical degree important. Therefore this there must be dental health education program development will be able to improve, means must reflect the dental health education at the time of.

• Korean Journal of Environmental Agriculture
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• v.39 no.3
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• pp.237-245
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• 2020

BACKGROUND: The closed chamber method is the most commonly used for measuring greenhouse gas emissions from upland fields. This method has the advantages of being simple, easily available and economical. However, uncertainty estimation is essential for accurate assessment of greenhouse gas emissions and verification of emission reductions. The nitrous oxide emissions from upland field is very important for the nitrogen budget in the agriculture sectors. Although assessment of uncertainty components affecting nitrous oxide emission from upland field is necessary to take account of dispersion characteristics, research on these uncertainty components is very rare to date. This study aims at elucidation of influencing factors on measurement uncertainty of nitrous oxide concentrations measured by an automated open closed chamber method from upland field. METHODS AND RESULTS: The nitrous oxide sampling system is located in the upland field in Gyeonggi-do Agricultural Research and Extension Services (37°13'22"N, 127°02'22"E). The primary measurement uncertainty components influencing nitrous oxide concentrations (influencing factors) investigated in this research are repeatability, reproducibility and calibration in the aspects of nitrous oxide sampling and analytical instrumentation. The magnitudes of the relative standard uncertainty of each influencing factor are quantified and compared. CONCLUSION: Results of this study show what influencing factors are more important in determination of nitrous oxide concentrations measured using the automated open closed chambers located in the monitoring site. Quantifying the measurement uncertainty of the nitrous oxide concentrations in this study would contribute to improving measurement quality of nitrous oxide fluxes.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.349-359
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• 2014

Until now, wall-slab plate of steel plate concrete has been constructed by joint. But, the shear plate has problems in the workability as well as structural integrity. This study investigates the behavior and strength of rib stiffened SC wall-slab connection. Seven prototype specimens of wall-slab connections were fabricated and tested. the structural safety of the specimens was confirmed through the monotonic loading test. Based on the experimental observations, this study propose the strength formula of the joint was proposed. To enhance the reliability of the proposed strength formula, analytical verification was performed through inelastic finite element analysis. Effect of parameters, such as, load point, friction coefficient, on the joint strength was examined. The proposed formula yields a conservative value for most cases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.380-383
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• 2006

The media transport system is used in a printer, a ATM(Automated Tellor Machine), and so on. The media transport system has many problems through miniaturization and rapid transportation of these machines. In the paper feeding mechanism, it is important to feed the sheet without jamming under any conditions. To avoid sheet jamming, first we need to predict the behavior of the sheet exactly. In this paper, the analysis of media behavior is based on J. Stolte's studies. In all of OA machines, a flexible beam or plate is pushed from the channel. The motion may be constrained by guides. This leads to a transient and geometrically nonlinear problem. The behavior of paper is simulated by dynamic elastica theory. The shape of guide is represented by parametric cubic curve. But J. Stolte's studies did not considered contact condition between sheet and guide. So Klarbring's Model. will be applied. And the analysis of flexible media has to include aerodynamic effect for more exact behavior analysis, because the flexible media can be deformed drastically by a little force. Therefore aerodynamic force must be applied to the governing equation. Lastly, the simulation of this model is performed, and the experiment is performed for verification of this model. The experimental results of low exit velocity are consistent with the simulation results, however experimental results of high exit velocity do not agree well with analytical results. The reason is that there may be other effects like nip Phenomena

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.54-59
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• 2003

Several radionuclides are considered as an object of the assesment to develop a scaling factor and a periodical verification method which are needed for the evaluation of radionuclide inventory of various radioactive wastes from nuclear power plants in Korea. A selective separation of $^{55}Fe$, $^{90}FSr$ 및 $^{94}Nb$ which should be recovered individually for the radiochemical analysis was described in detail. Sorption and desorption behaviours of ion exchange and extraction chromatographic resins for Fe, Sr, Nb and co-existing metal ions were Investigated using an artificial waste solution simulated of chemical composition of real radioactive wastes. Separation conditions available for the sequential recovery of these metal ions from a single sample were optimized to minimize a discharge of radioactive wastes produced through the analytical process and a radiation exposure to analysts. Their recovery yields were measured with reliability.

• The Korean Journal of Health Service Management
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• v.5 no.3
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• pp.13-23
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• 2011

This paper investigated the operating environment for the representative of each agency and the facility workers on the basis of analytical result of recognition changes of the operating environment changes under the operating the long-term care insurance. It was described plans to take positive effect on the operating as follows. The first, on the result of regression analysis, the service administrative range takes the biggest effect on the general recognition of executing the long-term care insurance off and on. The affirmative recognition of the service administrative range had the general recognition on the system be positive effect. But the operator of facility asserts that the care manager's professionalism related quality of service be strengthened. The second, on the result of regression analysis, in the financial accounting administrative it is revealed the more positive recognition it is, the more positive effects it has. From the difference verification of an operation size from operation subject, the small operation size and personal facility recognize the long term care insurance positively. On the other side the facilities where the operation size is big recognize the system negatively. The long-term care facility should rearrange a support program newly and the government needs to promote the donation activity, because it is needed to reduce the financial burden of facilities.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5342-5348
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• 2014

Slope stability analyses were conducted to investigate the limitations of application of the standard inclination of slope and the effects of the berm width on the slope stability. The standard slope inclination could be applied to the basic slope sections that were considered for the analyses, whereas additional slope stability analysis should be performed for the case of considering ground water. A comparison of the factors of safety between the case of installing a berm and the case of letting the grading have an equivalent section area with the case of installing the berm, the factors of safety in the case of installing a berm were greater than those for the case of allowing grading, and the differences between the factors of safety increase with increasing berm width. For all the sections considered in the analyses, the increments of the safety factor were proportional to the width of the berm and those corresponding to the embankment slope and cut slope with a berm width of 7m were 34.5% and 48%, respectively.

• Journal of the Korean Magnetics Society
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• v.24 no.4
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• pp.107-113
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• 2014

In this paper, a optimum degaussing technique, which can minimize an underwater magnetic field anomaly generated by the ferromagnetic hull, was verified through the mock-up test of a ship. To predict degaussing field signals due to the degaussing coils installed in a ship, individual coil effects were measured. Exploiting the linearity of coil effects and analytical sensitivity formula, optimum degaussing current values fed to individual coils were decided. To identify degaussing performance of the proposed method, the obtained degaussing currents were applied to the coils. Then the field anomaly signals were measured and analyzed before and after degaussing. Experimental results show the magnitude of the field signal after degaussing is reduced up to 95% of that before degaussing.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.27-36
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• 2011

In the proposed paper numerical calculations are carried out using two versions of a three-dimensional, timedomain panel method developed by the group of Prof. P. Sclavounos at MIT, i.e. the linear code SWAN2, enabling optionally the use of the instantaneous non-linear Froude-Krylov and hydrostatic forces and the fully non-linear SWAN4. The analytical results are compared with experimental results for three hull forms with increasing geometrical complexity, the Series 60, a reefer vessel with stern bulb and a modern fast ROPAX hull form with hollow bottom in the stern region. The details of the geometrical modeling of the hull forms are discussed. In addition, since SWAN4 does not support transom sterns, only the two versions of SWAN2 were evaluated over experimental results for the parent hull form of the NTUA double-chine, wide-transom, high-speed monohull series. The effect of speed on the numerical predictions was investigated. It is concluded that both versions of SWAN2 the linear and the one with the non-linear Froude-Krylov and hydrostatic forces provide a more robust tool for prediction of the dynamic response of the vessels than the non-linear SWAN4 code. In general, their results are close to what was expected on the basis of experience. Furthermore, the use of the option of non-linear Froude-Krylov and hydrostatic forces is beneficial for the accuracy of the predictions. The content of the paper is based on the Diploma thesis of the second author, supervised by the first one and further refined by the third one.