• Journal of the Korean Mathematical Society
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• v.34 no.2
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• pp.293-307
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• 1997

In this paper we present the $L^2$-estimation for the kernel $K_n$ of the remaider term for the Gaussian quadrature with respect to one of four Chebyshev weight functions and the error bound of the type on the contour $$ $\mid$R_n(f)$\mid$ \leq \frac{2\pi}{\sqrt{l(\Gamma)}} max_{z\in\Gamma}$\mid$f(z)$\mid$ (\smallint_\Gamma $\mid$K_n(z)$\mid$^2$\mid$dz$\mid$)^\frac{2}{1}, $$ where $l(\Gamma)$ denotes the length of the contour $\Gamma$.

• The Korean Journal of Applied Statistics
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• v.22 no.6
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• pp.1345-1353
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• 2009

We introduce a simple methodology, so-called generalized gamma-polynomial approximation, based on moment-matching technique to approximate survival and hazard functions in the context of parametric survival analysis. We use the generalized gamma-polynomial approximation to approximate the density and distribution functions of convolutions and finite mixtures of random variables, from which the approximated survival and hazard functions are obtained. This technique provides very accurate approximation to the target functions, in addition to their being computationally efficient and easy to implement. In addition, the generalized gamma-polynomial approximations are very stable in middle range of the target distributions, whereas saddlepoint approximations are often unstable in a neighborhood of the mean.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.439-442
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• 2003

This study was conducted to choose optimal distribution and to estimate properly parameters for the derivation of design rainfall in Gamma Family. Design rainfall derived by Gamma Family Distributions were compared by the Relative Mean Errors(RME) and Relative Absolute Errors(RAE) for the consecutive durations of 1, 3, 6, 12, 24, 36, 48 and 72hr and 65 regions all over the regions except Cheju and Wulreung islands in Korea. Consequently, Design rainfall derived by Indirect Method of Moments in the Log-Pearson Type 3 distribution are seemed to be more reasonable than those of other distributions in Gamma Family.

• Journal of Radiation Protection and Research
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• v.30 no.4
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• pp.161-165
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• 2005

The gamma-ray dose rates in air at 233 locations in Korea have been determined. The contribution to the gamma-ray dose rates in air due to the presence of $^{232}Th-series,\;^{238}U-series\;and\;^{40}K$ is as follows: 47.3% $(36\;nGyh^{-1})\;^{232}Th-series$ 14.5% $(11\;nGyh^{-1})\;^{238}U-series$ and 38.2% $(29\;nGyh^{-1})\;^{40}K$. The mean gamma-ray dose rate theoretically derived from $^{232}Th-series,\;^{238}U-series\;and\;^{40}K\;was\;76{\pm}17\;nGyh^{-1}$. This corresponds to an annual effective dose of $410\;{\mu}Sv$ and an annual collective dose of 18900 person-Sv for all provinces under study. The results have been compared with other global radiation dose.

• Journal of Broadcast Engineering
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• v.22 no.6
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• pp.702-712
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• 2017

In this paper, we propose an unsharp masking algorithm using Laplacian as a weight map for the signal structure and a gamma transformation algorithm using image mean intensity as a weight map for mean intensity. The conventional weight map based on the patch has a disadvantage in that the brightness in the image is shifted to one side in the signal structure and the mean intensity region. So the detailed information is lost. In this paper, we improved the detail using unsharp masking of patch unit and proposed linearly combined the gamma transformed values using the average brightness values of the global and local images. Through the proposed algorithm, the detail information such as edges are preserved and the subjective image quality is improved by adjusting the brightness of the light. Experiment results show that the proposed algorithm show better performance than conventional algorithm.

• Journal of Korean Neurosurgical Society
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• v.60 no.6
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• pp.667-675
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• 2017

Objective : Total resection without consecutive postoperative whole brain radiation therapy is indicated for patients with a single or two sites of brain metastasis, with close follow-up by serial magnetic resonance imaging (MRI). In this study, we explored the effectiveness, usefulness, and safety of this follow-up regimen. Methods : From January 2006 to December 2015, a total of 109 patients (76 males, 33 females) underwent tumor resection as the first treatment for brain metastases (97 patients with single metastases, 12 with two metastases). The mean age was 59.8 years (range 27-80). The location of the 121 tumors in the 109 patients was supratentorial (n=98) and in the cerebellum (n=23). The origin of the primary cancers was lung (n=45), breast (n=17), gastrointestinal tract (n=18), hepatobiliary system (n=8), kidney (n=7), others (n=11), and unknown origin (n=3). The 121 tumors were totally resected. Follow-up involved regular clinical and MRI assessments. Recurrence-free survival (RFS) and overall survival (OS) after tumor resection were analyzed by Kaplan-Meier methods based on clinical prognostic factors. Results : During the follow-up, MRI scans were done for 85 patients (78%) with 97 tumors. Fifty-six of the 97 tumors showed no recurrence without adjuvant local treatment, representing a numerical tumor recurrence-free rate of 57.7%. Mean and median RFS was 13.6 and 5.3 months, respectively. Kaplan-Meier analysis revealed the cerebellar location of the tumor as the only statistically significant prognostic factor related to RFS (p=0.020). Mean and median OS was 15.2 and 8.1 months, respectively. There were no significant prognostic factors related to OS. The survival rate at one year was 8.2% (9 of 109). Conclusion : With close and regular clinical and image follow-up, initial postoperative observation without prompt postoperative radiation therapy can be applied in patients of brain metastasi(e)s when both the tumor(s) are completely resected.

• Journal of Radiation Industry
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• v.5 no.4
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• pp.383-391
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• 2011

This study was conducted to investigate the applicability of gamma irradiation for improving the quality of paprika and Japanese apricot extract-treated nitrite free pork jerky. Pork jerky was gamma-irradiated at 0, 3, 5, 7 and 10 kGy and physiochemical properties such as proximate composition, 2-thiobarbituric acid (TBARS) values, color stability, texture, and sensory property were then evaluated. The results showed that the treatment of paprika and Japanese apricot extract to the pork jerky increased Hunter color value and texture property and at the same time decreased TBARS values. When gamma irradiated, natural pigment extract-treated pork jerky did not produce any change in its proximate composition (moisture, crude protein, crude lipid contents), and TBARS values. However, the redness (a-value) of pork jerky increased as the irradiation dose increased, whereas shear force of pork jerky was decreased. Sensory result showed that gamma irradiation induced to decrease the sensory scores. Therefore, these results suggest that gamma irradiation and the addition of paprika and Japanese apricot extracts could be an effective mean to improve color and texture of restructured pork jerky without use of nitrite.

• Korean Journal of Materials Research
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• v.25 no.11
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• pp.630-635
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• 2015

The fatigue strength of a nickel-base superalloy was studied. Stress-controlled fatigue tests were carried out at $700^{\circ}C$ and 5 Hz using triangular wave forms. In this study, two kinds of testing procedures were adopted. One is the conventional tension-zero fatigue test(R = 0). The other was a procedure in which the maximum stress was held at 1000 MPa and the minimum stress was diverse from zero to 1000 MPa at 24 and $700^{\circ}C$. The results of the fatigue tests at $700^{\circ}C$ indicate that the fracture mechanism changed according to both the mean stress and the stress range. At a higher stress range, ${\gamma}^{\prime}$ precipitates are sheared by a/2<110> dislocation pairs coupled by APB. Therefore, in a large stress range, the deformation occurred by shearing of ${\gamma}^{\prime}$ by a/2<110> dislocations, which brought about crystallographic shear fracture. As the stress range was decreased, the fracture mode gradually changed from crystallographic shear fracture to gradual growth of fatigue cracks. At an intermediate stress range, as it became more difficult for a/2<110> dislocation pairs to shear ${\gamma}^{\prime}$ particles, cracks started to propagate in the matrix, avoiding the harder ${\gamma}^{\prime}$ particles. High mean stress induced creep deformation, that is, ${\gamma}^{\prime}$ particles were sheared by {111}<112> slip systems, which led to the formation of stacking faults in the precipitates. Thus, the change in fracture mechanism brought about the inversion of the S-N curves.

• Journal of Preventive Medicine and Public Health
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• v.35 no.2
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• pp.169-174
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• 2002

Objective : To investigate gamma-Glutamyltransferase (${\gamma}-GTP$) and its related factors in male industrial workers. Method : Five hundred and tony male workers without heart disease, diabetes mellitus, renal disease, hepatitis, and other liver diseases were surveyed in October 1998. Blood samples were collected to test for ${\gamma}-GTP$, total-cholesterol and fasting blood glucose. A self-administered questionnaire survey on life style was also done. Results : The total geometric mean value of ${\gamma}-GTP$ was 30.6 U/L. According to a univariate analysis: age, BMI(body mass index, $kg/m^2$), alcohol consumption, current smoking, stress, diastolic blood pressure, and blood total cholesterol were significantly associated with ${\gamma}-GTP$(p<0.05). From a multiple regression analysis: BMI, alcohol consumption, current smoking, diastolic blood pressure and total-cholesterol were significantly related to ${\gamma}-GTP$(p<0.05). Coffee consumption was negatively related to ${\gamma}-GTP$, but not significantly. Conclusion : We recommend that a change in health behavior (i.e. reducing alcohol intake, controlling BMI and not smoking) is necessary to decrease ${\gamma}-GTP$ in male workers.

• The Journal of Korean Medicine
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• v.23 no.1
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• pp.177-182
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• 2002

It is considered that herbal medicine may also have hepatotoxicity and Aconiti Radix Lateralis Preparata is thought to be the most poisonous. We investigated the changes of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and ${\gamma}-glutamyltranspeptidase{\;}({\gamma}-GT$)$ in 6 cases administrated herbal medicine containing Aconiti Radix Lateralis Preparata and tried to evaluate its influence on liver enzymes. Before administration, the mean values of AST and ALT were $30.5{\pm}12.4${\;}U/L{\;}and{\;}30.7{\pm}22.5{\;}U/L$. After administration, those of AST, ALT and ${\gamma}-GT{\;}were{\;}25.7{\pm}8.7 {\;}U/L,{\;}28{\pm}14.8{\;}U/L{\;}and{\;}34.3{\pm}19.4{\;}U/L$ respectively. Therefore, it is indirectly assured that herbal medicine containing Aconiti Radix Lateralis Preparata didn't influence liver enzymes such as AST, ALT, ${\gamma}-GT$.