• Journal of Intelligence and Information Systems
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• v.15 no.3
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• pp.1-15
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• 2009

In a classification problem, data imbalance occurs when the number of instances in one class greatly outnumbers the number of instances in the other class. Such data sets often cause a default classifier to be built due to skewed boundary and thus the reduction in the classification accuracy of such a classifier. This paper proposes a Geometric Mean-based Boosting (GM-Boost) to resolve the problem of data imbalance. Since GM-Boost introduces the notion of geometric mean, it can perform learning process considering both majority and minority sides, and reinforce the learning on misclassified data. An empirical study with bankruptcy prediction on Korea companies shows that GM-Boost has the higher classification accuracy than previous methods including Under-sampling, Over-Sampling, and AdaBoost, used in imbalanced data and robust learning performance regardless of the degree of data imbalance.

• Computational Structural Engineering
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• v.10 no.1
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• pp.173-183
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• 1997

In this paper a method is suggested for the probabilistic analysis of impact buckling failure time of cylinder with random axisymmetric geometric imperfection under axial impact. Failure is assumed as axisymmetric radial deformation exceeds the given criteria for the first time. For the generation of random geometric initial imperfection, random field theory by mean function and autocorrelation function of geometric imperfection is used. Suggested method is useful for the treatment of the randomness of realistic geometric imperfection and can be used for the structural safety analysis of cylinder considering its effect.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.4
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• pp.493-505
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• 2015

Objectives: The purpose of this study was to evaluate the relevance of adjusting a urinary sample for urine hippuric correction value and its effects. Urinary biological monitoring data are typically adjusted to a constant creatinine and specific gravity concentration to correct for variable dilutions among spot samples. This study was conducted to evaluate the suitability of adjusting the urinary concentrations of urine creatinine and specific gravity(SG). Methods: We measured the concentrations of hippuric acid, in spot urine samples collected from control(119), case(120) individuals. The value of hippuric acid was adjusted by SG and urinary creatinine(HPLC & Jaffe). Results: The major results were as follows. The concentrations of urinary creatinine and SG for the control group were 1.84 g/L(SD 0.99) for arithmetic mean and 1.56 g/L(GSD 1.86) for geometric mean by HPLC method, 1.57 g/L (SD, 0.82) for arithmetic mean and 1.33 g/L(GSD 1.85) for geometric mean by Jaffe method, 1.028(SD 0.09) for arithmetic mean and 1.02(GSD 1.06) for geometric mean by refractometer. Hippuric acid levels were 0.40 g/L(SD 0.51) by arithmetic mean and 0.20 g/L(GSD 3.59). In that case the exposed group was 1.40 g/L(SD 0.58) for arithmetic mean and 1.28 g/L(GSD 1.55) for geometric mean by HPLC method, 1.27 g/L(SD 0.56) for arithmetic mean and 1.14 g/L(GSD 1.62) for geometric mean by Jaffe method, 1.045 L(SD 0.27) for arithmetic mean and 1.02(GSD 1.13) for geometric mean by refractometer(P<0.05). Hippuric acid levels were 0.67 g/L(SD 0.79) for arithmetic mean and 0.39 g/L(GSD 2.94)(p<0.05). The urine creatinine concentrations were affected by gender(p < 0.01) but SG levels were not affected by gender or age(p>0.05). After adjustment, urine hippuric acid was correlated with creatinine(HPLC & Jaffe)(r=0.723, P<0.05, r=0.708, P<0.05) and SG(r=0.936, P<0.05) and the control group shows significantly higher than the case group. In the case group for adjusted urine hippuric acid was correlated with creatinine(HPLC & Jaffe), (r=0.736, P<0.05), r=0.549, P<0.05), SG(r=0.549, P<0.05). After adjusting urine hippuric acid by urine creatinine(HPLC and Jaffe method) and specific gravity, significant associations were found between the control group and case group, respectively(r=0.832, P<0.05, r=0.845, P<0.05) and (r=0.841, P<0.05, r=0.849, P<0.05). Specific gravity adjustment appears to be more appropriate for variations in the urine creatinine method. Conclusion: we found that urinary creatinine concentrations were significantly affected by gender, and other factors and that care should therefore be exercised when correcting urinary metabolites according to the urinary creatinine concentration in spot urine. It is determined that additional study is needed for biological monitoring.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.197-212
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• 1997

The performance of a torque converter can be expressed by the performance parameters such as flow radius and flow angle, on the mean flow path. The geometric analysis of the torque converter is required to determine these parameters for the modeling of the torque converter. In general, the blade shape is depicted by three dimensional data at the mid-surface of blade or those of the pressure and suction side. To generate three dimensional model of the blade using the data mentioned above, a consistent data format and a shape generation algorithm are required. This paper presents a useful consistent data format of the blades and an algorithm for the geometrical shape generation. By the geometric analysis program to which the shape generation algorithm is embedded, the variation of blade angles in rotating element analyzed. Then finally, the analyzed results of geometric profile of a blade are compared with those of the blade design principle, so called forced vortex theorem.

• International Journal of Reliability and Applications
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• v.12 no.1
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• pp.49-60
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• 2011

The geometric process (GP) has been widely used for modeling failure and repair time sequences of repairable systems. The GP is mathematically tractable but restrictive in reliability applications since it actually assumes that the mean function of inter-failure times sequence asymptotically decreases to zero; and the mean function of successive repair times sequence asymptotically increases to infinity. This is generally unrealistic from an engineering perspective. This paper presents three extended GP models for modeling reliability deterioration and improvement (or growth) process. The extensions maintain the advantage of mathematical tractability of GP model. Their usefulness and appropriateness are illustrated with three real-world examples.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.218-220
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• 2004

Orthogonal frequency division multiplexing(OFDM) is one of the most promising technique for next generation wireless broadband communication systems. In this paper, we propose a new bit allocation algorithm in multiuser OFDM. The proposed algorithm is derived from the geometric progression of the additional transmit power of subcarriers and the arithmetic-geometric means inequality. The simulation shows that this algorithm has similar performance to the conventional adaptive bit allocation algorithm and lower computational complexity than the existing algorithms.

• Kyungpook Mathematical Journal
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• v.47 no.4
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• pp.595-600
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• 2007

In this paper we consider weighted arithmetic and geometric means of several positive definite operators proposed by Sagae and Tanabe and we establish a reverse inequality of the arithmetic and geometric means via Specht ratio and the Thompson metric on the convex cone of positive definite operators.

• Korean Journal of Veterinary Service
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• v.37 no.3
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• pp.185-190
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• 2014

We investigated the serological prevalence of avian metapneumovirus (AMPV), avian reovirus (ARV), Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) in 760 broiler breeder (38 flocks), in the Jeonbuk province in 2013. This study was conducted to evaluate the immune and infection status of the broiler breeder flocks against AMPV, ARV, MG, MS by an enzyme-linked immunosorbent assay (ELISA). Serological test for AMPV were positive 37 (97.3%) flocks and 712 (93.6%) broiler breeder and geometric mean antibody titers were $16,350{\pm}10,195$, ARV were high positive rate 100% (38/38) flocks and 97.8% (743/760). The seropositive flocks against MG were 71.1% (27/38) and the geometric mean antibody titers were $2,474{\pm}2,045$, whereas the rates of positive flocks against MS were 50.0% (19/38) and the geometric mean antibody titers were $1,469{\pm}1,230$.

• East Asian mathematical journal
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• v.38 no.3
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• pp.331-338
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• 2022

In this paper, we prove that the first nonzero eigenvalues λ₁ of the Laplacian and the p-Laplacian are decreasing along the inverse mean curvature flow with forced term in Euclidean space.

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.55-64
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• 2004

Maximum dry unit weight, ${\gamma}_{dmax}$, is the most important engineering properties for subgrade soil. Existing models to predict ${\gamma}_{dmax}$ containing many parameters, seem to be rather complex. This paper presents new simple models to predict ${\gamma}_{dmax}$. for sandy soils, A number of sieve analysis and compaction tests for 36 types of sands were conducted to develop the regression-based models. Parameters used to estimate ${\gamma}_{dmax}$ are both the geometric mean and geometric standard deviation of the soils, or the particle-size distribution curve parameters. Maximum dry unit weights predicted by the models are in good agreement with the laboratory measurements for the soil samples obtained at 16 locations within the Korea.