• Journal of Environmental Science International
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• v.29 no.8
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• pp.793-800
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• 2020

The conventional development of multi-component electrodes is based on the researcher's experience and is based on trial and error. Therefore, there is a need for a scientific method to reduce the time and economic losses thereof and systematize the mixing of electrode components. In this study, we use design of mixture experiments (DOME)- in particular a simplex lattice design with Design Expert^Ⓡ program- to attempt to find an optimum mixing ratio for a three-component electrode for the high RNO degradation; RNO is an indictor of OH radical formation. The experiment included 12 experimental points with 2 center replicates for 3 different independent variables (with the molar ratio of Ru, Ti, Ir). As the Prob > F value of the 'Quadratic' model is 0.0026, the secondary model was found to be suitable. Applying the molar ratio of the electrode components to the corrected response model results is an RNO removal efficiency (%) = 59.89 × [Ru] + 9.78 × [Ti] + 67.03 × [Ir] + 66.38 × [Ru] × [Ir] + 132.86 × [Ti] × [Ir]. The R² value of the equation is 0.9374 after the error term is excluded. The optimized formulation of the ternary electrode for an high RNO degradation was acquired when the molar ratio of Ru 0.100, Ti 0.200, Ir 0.700 (desirability d value, 1).

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.32-39
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• 2004

HCCI (Homogeneous Charge Compression Ignition) combustion has a great advantage in reducing NOx (Nitrogen Oxides) and PM (Particulate Matter) by lowering the combustion temperature due to spontaneous ignitions at multiple sites in a very lean combustible mixture. However, it is difficult to make a diesel-fuelled HCCI possible because of a poor vaporability of the fuel. To resolve this problem, the two-stage injection strategy was introduced to promote the ignition of the extremely early injected fuel. The compression ratio and air-fuel ratio were found to affect not only the ignition, but also control the combustion phase without a need for the intake-heating or EGR (Exhaust Gas Recirculation). The ignition timing could be controlled even at a higher compression ratio with increased IMEP (Indicated Mean Effective Pressure). The NOx (Nitrogen Oxides) emission level could be reduced by more than 90 % compared with that in a conventional DI (Direct Injection) diesel combustion mode, but the increase of PM and HC (Hydrocarbon) emissions due to over-penetration of spray still needs to be resolved.

• Journal of Elementary Mathematics Education in Korea
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• v.14 no.3
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• pp.769-788
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• 2010

This study analyzed the characteristics of units about ratio and rate between Korean mathematics textbooks and MIC of America. With bases to this, I would find the problems and suggested point of curriculums about ratio and rate in order to propose the basic materials of developing mathematic curriculum and textbook and improving the mathematic teaching method. With bases to this, Korean mathematics textbooks should be supplemented as follows. A. Develop the various problems with meaningful situation rather than the problems which can be solved with algorithms and rules. B. Develop the students' rational judgement competence with the situation that can induce the active communication. C. Develop the problem situation that need the student's activity. D. Let the students easily take the situation about ratio and rate with suggesting much visual mode and sustain their interest and positive learning attitude.

• Journal of the Korean Data and Information Science Society
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• v.10 no.1
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• pp.29-36
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• 1999

We propose a new method of asymptotic inference on the odds ratio (or cross-product ratio) in $2{\times}2$ contingency table. Saddlepoint approximations to the conditional tail probability we used in this procedure. We assess the accuracy of the suggested method by comparing with the exact one. To obtain the exact values, we need very complicated calculations containing the cumulative probabilities of non-central hypergeometric distribution. The suggested method in this paper is very accurate even for small or moderate sample sizes as well as simple and easy to use. Example with a real data is also considered.

• Journal of the Korea Safety Management & Science
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• v.12 no.2
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• pp.209-216
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• 2010

We need a study of the ratio of successful applicants control methodology about the national technical qualification under the global-green industrial society and rapid change of international circumstances, infinite competition rider society under FTA aspects. It is necessary to develop of HRD Korea selfishness and increase brand value of national technical qualification. So, this study is analysed to the ratio of successful applicants of national technical qualification toward change of the 'bank of problems' control rule, various characters of candidates and the trend of demand and supply of labours instead of the absolute evaluation method. Accordingly, this study suggests to a methodology for the forecasting model of the ratio of successful applicants using the level of problems difficulty and pattern and the candidates academical carriers.

• KIEAE Journal
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• v.5 no.3
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• pp.17-24
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• 2005

Until today, rainwater management was processed without disposing the peak discharge, which was due to rainfall, to provide stability against flood damage. In this process, the natural hydrologic cycle changed quickly, and because of this, some problems that could harm human beings and the environment arose. These problems need to be addressed accordingly. One of the proposals was to carry out decentralized rainwater management through a natural hydrologic cycle on site, including utilization, infiltration, detention, and retention of rainwater. This study aims to set the direction of applicable decentralized rainwater management to housing complex in Korea. Therefore, spacial properties in urban housing complexes were analysed such as the impervious area-to-land ratio, the green area-to-land ratio, artificial land-to-land ratio etc. As the result of this study, when a housing complex was small and developed by reconstruction, the impervious area, artificial land, the green area in the artificial land-to-land ratio were high. So, direction of decentralized rainwater management of these housing complexes is available to utilize and detain rainwater. On the other hand, those of big housing complexes in land development district were low relatively. So, direction of decentralized rainwater management of these housing complexes is available to infiltrate and evaporate rainwater.

• Journal of Society of Preventive Korean Medicine
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• v.18 no.1
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• pp.43-52
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• 2014

This study was conducted to analyze if there is a difference between the head hospital and branch hospital by comparing the profitability and operating expenses to patient revenue of oriental medicine hospitals affiliated with universities in order to find whether opening branch hospitals is an appropriate method to increase profitability. Profit indices used for the comparison of head hospital and branch hospital include ratio of operating profit on medical revenue, net-income on medical revenue, net profit to total assets, and operating profit to total assets; and cost indices included ratio of labor costs, material costs and administrative costs. In comparison of profit indices of head hospitals and branch hospitals, head hospitals displayed negative(-) in all four profit index averages while branch hospitals displayed positive(+), showing that branch hospitals have higher profitability. In particular, in the case of head hospitals, ratio of net profit to total assets was -13.6%, while that of branch hospitals was 12.9%, which was higher than 3.1%, the average of Korean oriental medicine hospitals in 2011. As a result of difference analysis between groups of head hospitals and branch hospitals, profit indices of ratio of operating profit on medical revenue, net-income on medical revenue, and ratio of net profit to total assets were found to vary by hospitals, but there was no statistically significant difference between head hospitals and branch hospitals(p<0.1). Only the ratio of operating profit to total assets of head hospitals and branch hospitals indicated significant difference between the two groups, showing that ratio of operating profit to total assets of branch hospitals is larger than that of head hospitals. Meanwhile, the cost indices of ratio of labor costs, material costs and administrative costs in the difference test results did not show significant difference between the head hospital and branch hospital(p<0.1). Thus, it cannot be said that a certain oriental medicine hospital's profitability is high or low depending on whether it is head hospital or a branch as profitability varies depending on the management environment of the hospital. Therefore, oriental medicine hospitals affiliated with universities would need to make efforts to increase their profitability as an individual hospital rather than focusing on whether they are head hospital or a branch.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.39-47
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• 2015

Objective : The purpose of this study was to investigate the velocity conversion coefficient and invariance for the optimal phase ratio on the performance of the women's triple jump. Methods : Three-dimensional kinematic data were obtained from the three finalists of the women's triple jumper competition at the 2011 Daegu IAAF World Championships. Computer simulations were performed using the biomechanical model of the triple jump to optimize the phase ratio for the longest actual distance for all athletes with altered velocity conversion coefficients. Results : Top elite triple jumpers showed better technical consistency at the phase ratio. Also, no consistent relationship was observed between the loss in horizontal velocity and the gain in vertical velocity across supporting the three phase. In addition, regardless of the magnitude A1, all athletes were optimized with jump-dominated technique. Finally, as the magnitude of A1 increased, the athletes showed better performance. The obtained overall distance jumped showed the longest actual distance when the optimal phase ratio was transferred from hop-dominated to jump-dominated(the step ratio was 30%~31%), and when the optimal phase ratio was transferred from balanced to jump-dominated(the step ratio was 27%~29%). Conclusion : Future studies need to be conducted in order to explore the active landing motion and the inclination angle of the body with the velocity conversion coefficient simultaneously at each supporting phase.

• Culinary science and hospitality research
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• v.15 no.4
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• pp.212-226
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• 2009

This study attempted to analyze the correlation between financial ratio and operating performance of foodservice companies, using the financial data by DART service. Financial ratio is an index to identify the management of foodservice companies from calculating the ratio associating two accounts in the financial statements. Managers, creditors and investors often have different purposes for using the ratio analysis to evaluate the contents of the financial statements. According to the analysis of financial ratio and operating performance, listed food and beverage companies proved to have a high correlation in all except for interest coverage. However, foodservice companies showed a high correlation in stability and growth ratio. Therefore, managers of the foodservice companies will need to improve operating performance for using efficient utilization plans of debt from assets and operating expenses(cost of goods sold, general and other expenses).

• Steel and Composite Structures
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• v.19 no.5
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• pp.1167-1184
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• 2015

Despite considerable life casualty and financial loss resulting from past earthquakes, many existing steel buildings are still seismically vulnerable as they have no lateral resistance or at least need some sort of retrofitting. Passive control methods with decreasing seismic demand and increasing ductility reduce rate of vulnerability of structures against earthquakes. One of the most effective and practical passive control methods is to use a shear panel system working as a ductile fuse in the structure. The shear Panel System, SPS, is located vertically between apex of two chevron braces and the flange of the floor beam. Seismic energy is highly dissipated through shear yielding of shear panel web while other elements of the structure remain almost elastic. In this paper, lateral behavior and related benefits of this system with narrow-flange link beams is experimentally investigated in chevron braced simple steel frames. For this purpose, five specimens with IPE (narrow-flange I section) shear panels were examined. All of the specimens showed high ductility and dissipated almost all input energy imposed to the structure. For example, maximum SPS shear distortion of 0.128-0.156 rad, overall ductility of 5.3-7.2, response modification factor of 7.1-11.2, and finally maximum equivalent viscous damping ratio of 35.5-40.2% in the last loading cycle corresponding to an average damping ratio of 26.7-30.6% were obtained. It was also shown that the beam, columns and braces remained elastic as expected. Considering this fact, by just changing the probably damaged shear panel pieces after earthquake, the structure can still be continuously used as another benefit of this proposed retrofitting system without the need to change the floor beam.