• Communications for Statistical Applications and Methods
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• v.18 no.4
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• pp.485-493
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• 2011

The proportional likelihood ratio order is an extension of the likelihood ratio order for the non-negative absolutely continuous random variables. In addition, the Lindley distribution has been over looked as a mixture of two exponential distributions due to the popularity of the exponential distribution. In this paper, we first recalled the above concepts and then obtained various properties of the Lindley distribution due to the proportional likelihood ratio order. These results are more general than the likelihood ratio ordering aspects related to this distribution. Finally, we discussed the proportional likelihood ratio ordering in view of the weighted version of the Lindley distribution.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.17-28
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• 2011

This study applied the Kalman Filter for real-time forecasting the G/R (ground rain gauge rainfall/radar rainfall) ratio to correct the mean field bias of the very-short-range-forecast (VSRF) rainfall. The MAPLE-forecasted rainfall was used as the VSRF rainfall, also the methodology for deciding the G/R ratio was improved by evaluating the change of G/R ratio characteristics depending on the threshold and accumulation time. This analysis was done for the inland, mountain, and coastal regions, separately, for their comparison. As the results, more stable G/R ratio could be estimated by applying the threshold and accumulation time, whose forecasting accuracy could also be secured. The accuracy of the corrected rainfall forecasting by the forecasted G/R ratio was the best in the inland region but the worst in the coastal region.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.129-138
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• 2008

In case of judging the stability of dike or dam structures which need hydraulic interception, the first thing to do is to examine whether a piping phenomenon occurred or not. Generally, dike or dam structures are constructed while layer compacting is executed, so permeability is likely to be anisotropic- different from each other in hydraulic conductivity in the horizontal direction [$k_x$] and hydraulic conductivity in the vertical direction[$k_y$]. This study looked into exit hydraulic gradient and Seepage velocity by conducting an Seepage analysis subsequent to various hydraulic conductivity ratios[k-ratio = ky / kx] and examined the influence on piping by comparing & examining critical Seepage Velocity based on critical hydraulic gradient in theoretical equation and critical Seepage Velocity in empirical equation. As the research result, it was found that hydraulic conductivity ratio operates as a very important factor in case the stability against piping occurrence is considered with the concept of critical hydraulic gradient, but relatively the hydraulic conductivity ratio is very low in its importance in relation to the concept of critical Seepage Velocity.

• Journal of Gastric Cancer
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• v.21 no.1
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• pp.84-92
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• 2021

Purpose: To date, no studies have been performed on staging based on the lymph node ratio (LNR) in elderly patients with gastric cancer who may require limited lymph node (LN) dissection due to morbidity and tissue fragility. We aimed to develop a new N staging system using the LNR in elderly patients with gastric cancer. Materials and Methods: The present study included patients aged over 75 years who underwent curative gastrectomy between January 1989 and December 2018. Clinicopathological data including the number of retrieved and metastatic LNs were collected and the LNR values were obtained (LNR = the number of metastatic LNs/the number of retrieved LNs). Eleven LNR groups with intervals of 0.1 were divided into four stages based on the inflection points at which the hazard ratio (HR) increased. Survival analysis was performed to evaluate the prognostic value of the LNR. Results: The four LNR stages included LNR0 (n=364), LNR1 (n=128), LNR2 (n=103), and LNR3 (n=10). In the multivariate analysis, both N staging and LNR staging exhibited significant prognostic values for predicting survival outcomes. However, the incremental change in the hazard ratio (HR) between consecutive stages was greater for the LNR staging than for the N staging (HRs: 1.607, 2.758, and 3.675 for N staging; 1.583, 3.514, and 10.261 for LNR staging). Conclusions: LNR staging is more useful than N staging in predicting the prognosis in elderly patients with gastric cancer and may be used as a complement or alternative to N staging.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.1
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• pp.13-20
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• 2019

Objective: This study was performed to propose a domestic occupational exposure limit(OEL) following a health hazard assessment, calculation of a non-carcinogenicity reference concentration worker($RfC_{worker}$) value, and examination of international agencies' exposure limits. It also recommends legal management within the Occupational Safety and Health Act for PHMG-Phosphate(CAS No. 89697-78-9), It is a humidifier disinfectant that generated many lung injuries. Methods: We have investigated the recommendation or guidelines of foreign OEL for PHMG-Phosphate and the actual state of legal management in Korea. To examine the procedures and methods for recommendation OEL. Toxicological hazard and health hazard classifications were examined and a non-carcinogenicity $RfC_{worker}$ value was calculated for PHMG-Phosphate. An OEL and the necessity of legal management were recommended as well. Results and Conclusions: The OEL for PHMG-Phosphate is recommended to be $0.01mg/m^3$. The recommended OEL is close to 10 times the RfCworker value of $0.000833mg/m^3$ calculated from the chemical dose-response hazard assessment, which is a 2017 study. The CMIT/MIT(3:1) mixture, which was a social issue as a humidifier disinfectant substance, was also exposed to the same ratio in March 2018, establish the OEL. It is recommended to establish OEL for PHMG-Phosphate to prevent worker health hazards and for chemical safety management.

• Journal of the Korean Data and Information Science Society
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• v.17 no.4
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• pp.1067-1076
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• 2006

Although the proportional hazards model is the most common approach used for studying the relationship of event times and covariates, alternative models are needed for occasions when it does not fit data. In the two-sample case, proportional odds models are useful for fitting data whose hazard rates converge asymptotically. In this thesis, we propose a new estimator of the relative odds ratio of the proportional odds model when two independent random samples are observed under uncensorship. We prove the asymptotic normality and consistency of the estimator by using martingale-representation. The efficiency of the proposed is assessed through a simulation study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.94-103
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• 2016

This study was conducted to investigate the association of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) with all-cause mortality among populations. The data used were from a Korean Genome and Epidemiology Study (KoGES) based on health examinations and questionnaires. The subjects consisted of 10,110 persons aged 40 and over. Hazard ratio was analyzed using Cox's proportional hazard model. The hazard ratio of AST (${\geq}50.0\;IU/L$) was 2.198 (95% CI: 1.217-3.971) after being adjusted for age, sex, education, regular exercise, smoking, drinking, WHR, and TG. In conclusion, AST was an independent significant risk factor of all-cause mortality, and ALT showed a tendency to increase. Overall, these findings indicate that AST and ALT may be useful tools for predicting mortality.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.123.1-123.1
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• 2009

• Radiation Oncology Journal
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• v.35 no.3
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• pp.249-256
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• 2017

Purpose: We retrospectively reviewed the results of radiotherapy for localized ocular adnexal MALT lymphoma (OAML) to investigate the risk factors of cataract. Methods: Sixty-seven patients with stage IE OAML treated with radiotherapy at Seoul St. Mary's Hospital from 2001 to 2016 were included. Median treatment dose was 30 Gy. Lens protection was done in 52 (76%) patients. Radiation therapy (RT) extent was as follows: superficial (82.1%), tumor mass (4.5%), and entire orbital socket (13.4%). The risk factors for symptomatic cataract were analyzed using the Cox proportional hazard model. Results: Median follow-up time was 50.9 months (range, 1.9 to 149.4 months). All patients were alive at the time of analysis. There were 7 recurrences and there was no local recurrence. Median time to recurrence was 40.4 months. There were 14 cases of symptomatic cataract. Dose >30 Gy had hazard ratio of 3.47 for cataract (p = 0.026). Omitting lens protection showed hazard ratio of 4.10 (p = 0.008). Conclusions: RT achieves excellent local control of ocular MALT lymphoma. Consideration of RT-related factors such as lens protection and radiation dose at the stage of RT planning may reduce the risk of RT-induced cataract after radiotherapy.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7681-7684
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• 2013

Background: Human leukocyte antigen (HLA)-G-positive gastric cancers are associated with poor survival, but links with tumor escape mechanisms remain to be determined. Materials and Methods: We used immunohistochemistry to investigate HLA-G expression, tumor infiltrating CD8+ T lymphocytes, and Treg cells in 52 gastric cancer patients. Results: There were 29 cancer-related deaths during the follow-up period. Kaplan-Meier analysis indicated that patients with HLA-G-positive (n=16) primary tumors had a significantly poorer prognosis than patients with HLA-G-negative tumors (n=36, p=0.008). The median survival time was 14 months and 47 months, respectively. Patients with high numbers of Tregs and low numbers of CD8+T lymphocytes in the primary tumor had a poorer prognosis than those with low numbers of Tregs and high numbers of CD8+T lymphocytes (p=0.034, p=0.043). Multivariate Cox proportional hazard regression analysis showed that HLA-G expression (hazard ratio: 2.662; 95% confidence interval: 1.242-5.723; p=0.012) and stage (hazard ratio: 2.012;95% confidence interval: 1.112-3.715; p=0.041) were independent unfavorable factors for patient survival. Conclusions: We found a significant positive correlation between HLA-G expression and the number of tumor infiltrating Tregs (p=0.01) and a negative correlation with the number of CD8+T lymphocytes (p=0.041). HLA-G may protect gastric cancer cells from cytolysis by inducing Foxp3+Treg lymphocytes and suppressing CD8+T lymphocytes.