• The KSFM Journal of Fluid Machinery
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• v.2 no.3 s.4
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• pp.52-58
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• 1999

The leakage and rotordynamic coefficients of see-through type gas labyrinth seals are determined using a two-control-volume-model analysis with Moody's wall-friction-factor formula which is defined with a large range of Reynolds number and relative roughness. Jet flow theory are used for the calculation of the recirculation velocity in the cavity. For the reaction force from the labyrinth seal, linearized zeroth-order and the first-order perturbation equations are developed for small motion about a centered position. The leakage and rotordynamic coefficient results of the present analysis are compared with Scharrer's theoretical analysis using Blasius' wall-friction-factor formula and Pelletti's experimental results. The comparison shows that the present analysis using Moody's wall-friction-factor formula and Scharrer's theoretical analysis using Blasius' wall-friction-factor formula give the same results for a smooth seal surface and the range of Reynolds number less than $10^5$.

• Journal of Wetlands Research
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• v.2 no.1
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• pp.49-58
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• 2000

The frequency analysis of annual maximum rainfall data and the derivation of probable rainfall intensity formula at Masan station are performed in this study. Based on the eight different rainfall duration data from 10 minutes to 24 hours, eight types of probability distribution (Gamma, Lognormal, Log-Pearson type III, GEV, Gumbel, Log-Gumbel, Weibull, and Wakeby distributions), three types of parameter estimation scheme (moment, maximum likelihood and probability weighted methods) and three types of goodness-of-fit test (${\chi}^2$, Kolmogorov-Smirnov and Cramer von Mises tests) were considered to find an appropriate probability distribution at Masan station. The Lognormal-2 distribution was selected and the probable rainfall intensity formula was derived by regression analysis. The derived formula can be used for estimating rainfall quantiles of the Masan vicinity areas with convenience and reliability in practice.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.29-35
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• 2014

The formula contains up between the text and the structural information, as well as their mathematical symbols. Research on-line or off-line recognition formula is underway actively used in various fields, and various forms of the equation are implemented recognition system. Although many documents are included in the various formulas, it is not easy to enter a formula into the computer. Recognition of the expression is divided into two processes of symbol recognition and structural analysis. After analyzing the location information of each character is specified to recognize the effective area after each symbol, and to the structure analysis based on the proximity between the characters is recognized as an independent single formula. Furthermore, analyzing the relationship between the front and back each time a combination of the position relationship between each symbol, and then to add the symbol which was able to easily update the structure of the entire formula. In this paper, by using a scanner to scan the book formula was used to interpret the meaning of the recognized symbol has a relative size and location information of the expression symbol. An algorithm to remove the formulas for calculation of the number of formula is present at the same time is proposed. Using the proposed algorithms to scan the books in the formula in order to evaluate the performance verification as 100% separation and showed the recognition rate equation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.4
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• pp.374-383
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• 2020

At ship design stage, the maneuverability is generally estimated based on the empirical formula or the computational fluid dynamic (CFD), which is one of the numerical simulation methods. Using the hydrodynamic derivatives derived through these methods can quantitatively estimate the maneuverability of target vessels and evaluate indirect maneuverability. Nevertheless, research on estimating maneuverability is insufficient for ships not subject to IMO maneuverability standard, especially fishing vessels, and even at the design stage, the empirical formula developed for merchant ships is applied without modification. An estimation error may occur due to the empirical formula derived from the regression analysis results of a model test if the empirical formula developed for merchant ships with different hull shapes is applied to fishing vessels without any modification. In this study, the modified empirical formula that can more accurately estimate the fishing vessel's maneuverability was derived by including the hull shape parameter of target fishing trawlers in the regression analysis process that derives Kijima et al. (1990) formula. As a result, the modified empirical formula showed an average estimation error of 6%, and the result improved the average error of 49% of Kijima et al. (1990) formula developed for merchant ships.

• Journal of the korean Society of Automotive Engineers
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• v.6 no.1
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• pp.71-77
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• 1984

Stress analysis of split ring with four different radius ratios under the compressive load is made by the photoelastic experiment and the numerical analysis through the FEM. The results of the two methods agreed well. Above results are also compared with those of the theoretical formula in order to confirm the range in which the formula of the curved bar is applied in connection with the radius ratio. The results of the two methods agreed well with those of the formula for the radius ratio, 3/2 and 9/7 within small errors of around 7% and 5% respectively.

• Journal of Korean Port Research
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• v.12 no.2
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• pp.373-384
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• 1998

In search and rescue mission the leeway formula based on the field experiments are utilized for the estimation of wind effect on distressed targets. This paper summarized the leeway formula from the available references. In the summary the environmental data collection method and experimental conditions are described along with the formula. Also the formula currently used in CASP of the U.S. Coast Gurard and CANSARP of the Canadian Coast Guard are discussed.

• Herbal Formula Science
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• v.22 no.2
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• pp.87-103
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• 2014

Objectives : Herbal formulas are complicated to analyze and difficult to compose because of its mixed, complex features. So we discussed about how to compose herbal formulas effective and efficient by analyzing various effectiveness of each herbal extracts. Methods : To evaluate the effectiveness of herbal formula, anti-oxidative and anti-inflammatory effectiveness were mathematically analyzed. DPPH, superoxide anions, Nitric Oxide scavenging activity was measured to evaluate the effectiveness of 7 herbal extracts. And next, cytotoxic activity of extracts on RAW 264.7 cells were measured using MTS assay. To asses anti-inflammatory effect, nitric oxide and $PGE_2$ production were measured. Based on these anti-oxidative and anti-inflammatory experiment result, mathematical analyzation were carried out with constOptm function, and determined efficacy-maximizing ratio. Results : This mathematical analysis based formula showed significantly outstanding effectiveness than other formulae. And estimated tendency of anti-inflammatory effectiveness was matched with real effectiveness. Conclusions : So, mathematical analysis can be available to evaluate and estimate the effectiveness of herbal formulae.

• Communications of the Korean Mathematical Society
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• v.37 no.2
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• pp.521-535
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• 2022

In this paper, we introduce the k-Hankel-Wigner transform on R in some problems of time-frequency analysis. As a first point, we present some harmonic analysis results such as Plancherel's, Parseval's and an inversion formulas for this transform. Next, we prove a Heisenberg's uncertainty principle and a Calderón's reproducing formula for this transform. We conclude this paper by studying an extremal function for this transform.

• Tribology and Lubricants
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• v.12 no.3
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• pp.115-122
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• 1996

In this paper, a finite difference method and the Newton-Raphson method are used to evaluate the Hamrock and Dowson's EHL film thickness formulas in elliptical contact problems. The minimum and central film thicknesses are compared with the Hamrock and Dowson's numerical results for various dimensionless parameters and with their film thickness formulas. The results of present analysis are more accurate and physically reasonable. The minimum film thickness formula is similar with the Hamrock and Dowson's results, however, the central film thickness formula shows large differences. Therefore, the Hamrock and Dowson's central film thickness formula should be replaced by following equation. $H_{c} = 4.88U^{0.68}G^{0.44}W^{0.096}(1-0.58e^{-0.60k})$ More accurate film thickness formula for general elliptical contact problems can be expected using present numerical methods and further research should be required.

• Computers and Concrete
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• v.6 no.3
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• pp.203-223
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• 2009

Regression analysis (RA) can establish an explicit formula to predict the strength of High-Performance Concrete (HPC); however, the accuracy of the formula is poor. Back-Propagation Networks (BPNs) can establish a highly accurate model to predict the strength of HPC, but cannot generate an explicit formula. Genetic Operation Trees (GOTs) can establish an explicit formula to predict the strength of HPC that achieves a level of accuracy in between the two aforementioned approaches. Although GOT can produce an explicit formula but the formula is often too complicated so that unable to explain the substantial meaning of the formula. This study developed a Backward Pruning Technique (BPT) to simplify the complexity of GOT formula by replacing each variable of the tip node of operation tree with the median of the variable in the training dataset belonging to the node, and then pruning the node with the most accurate test dataset. Such pruning reduces formula complexity while maintaining the accuracy. 404 experimental datasets were used to compare accuracy and complexity of three model building techniques, RA, BPN and GOT. Results show that the pruned GOT can generate simple and accurate formula for predicting the strength of HPC.