• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2B
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• pp.155-162
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• 2009

Univariate frequency analyses are widely used in practical hydrologic design. However, a storm event is usually characterized by amount, intensity, and duration of the storm. To fully understand these characteristics and to use them appropriately in hydrologic design, a multivariate statistical approach is necessary. This study applied a Gumbel mixed model to a bivariate storm frequency analysis using hourly rainfall data collected for 46 years at the Seoul rainfall gauge station in Korea. This study estimated bivariate return periods of a storm such as joint return periods and conditional return periods based on the estimation of joint cumulative distribution functions of storm characteristics. These information on statistical behaviors of a storm can be of great usefulness in the analysis and assessment of the risk associated with hydrologic design problems.

• Journal of dental hygiene science
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• v.14 no.2
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• pp.132-139
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• 2014

The aim of this study was to investigate the association between perceived periodontal status and sexual function among adult men. Three hundred thirty adult male participated in this study living at Changwon and Jinju. All the participants surveyed the socio-demographic characteristics, perceived periodontal status, stress, and international index of erectile function (IIEF) using self-administrated questionnaire. The univariate and multivariate analyze were adapted to access the crude and adjusted associations using PASW Statistics 18.0. In univariate analysis, there were significant differences between perceived periodontal status and IIEF and most of socio-demographic characteristics (p<0.05), but no significant differences between stress and all of socio-demographic characteristics (p>0.05). The sexual function was negatively correlated with perceived periodontal status (r=-0.228, p<0.001) and stress (r=-0.257, p<0.001), respectively. In multivariate analysis, perceived periodontal status was significantly associated with sexual function (b=-0.889, p=0.030) after adjusting for socio-demographic characteristics and stress. Therefore, it is found that perceived periodontal status negatively influenced on sexual function in adult men.

• Tuberculosis and Respiratory Diseases
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• v.46 no.1
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• pp.25-35
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• 1999

Background : The treatment for multi-drug resistant tuberculosis(MDRTB) is encountered to be important clinically, but there are still a few reports about it all over the world. So, we evaluated the outcomes of only chemotherapy for the pulmonary MDRTB retrospectively. Method: We reviewed the clinical courses of 63 patients with pulmonary disease due to M.tuberculosis resistant to rifampin and isoniazid who were under follow-up between March 1996 and June 1996 after hospitalization at our hospital between January 1993 and January 1996. We performed cohort retrospective study for all these patient's records. Their regimens were selected individually and preferably included four medications that they had not been given previously and to which the strain was fully susceptible. Results: The 63 patients(mean age, 43.2 years) had previously received a median 5.1drugs. Fifty two(82.5%) patients responded to chemotherapy(as indicated by negative sputum cultures for at least three consecutive months) ; eleven patients(17.5 %) had no response, as shown by continually positive cultures. In a univariate analysis, an unfavorable response was significantly associated with greater number of resistant drugs before the current courses of therapy(relative risk 21.5 ; 95 percent confidence interval, 1.2-3.0; p<0.05). The mean period of follow-up was seventeen months. There was no relapse suooequently among the patients with responses. There was no death related to tuberculosis. Conclusion: In this report from National Masan Tuberculosis Hospital in Korea, multi-drug resistant pulmonary tuberculosis responded relatively well to carefully selected regimens.

• Journal of Chest Surgery
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• v.42 no.1
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• pp.34-40
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• 2009

Background: The principal surgical technique for treating an abdominal aortic aneurysm since the 1960s has been the transperitoneal approach, yet there have been some recent studies that have reported improved surgical results with using the retroperitoneal approach. However, there are only limited clinical Korean studies that have, compared between the transperitoneal and retroperitoneal approaches. Material and Method: This study included 36 patients who had been diagnosed as having an aneurysm of the abdominal aorta and they were surgically treated between January 2001 and July 2007. The patients were subdivided into the retroperitoneal approach group (n=17) and the transperitoneal approach group (n=19), and they were compared in terms of the preoperative risk factors, the postoperative complications and the operative mortality. The risk factors of operative mortality risk and long-term survival for the 36 patients were assessed by the Kaplan-Meier method. Result: There were no significant differences between the groups in terms of gender, age, the underlying disease, a history of smoking, rupture of aneurysm, the preoperative symptoms, the operation time and the incidence of postoperative complications. However, the duration of postoperative fasting, the number of days of having an indwelling nasogastric tube and the length of the stay in the intensive care unit were significantly short for the retroperitoneal approach group (p<0.05). There was a 16.7% rate of operative mortality (6/36) and five of the deaths were attributed to preoperative ruptured aneurysm. On univariate analysis, a higher preoperative serum creatinine level (SCr ${\geq}$1.8 mg/dL, p=0.016) and ruptured aneurysm (p<0.001) were the significant risk factors of operative mortality. As assessed by the Kaplan-Meier method, the long-term survival was comparable between the groups and the five-year survival rate of all the patients was 57.5%. Conclusion: In the present study, a retroperitoneal approach has several advantages such as a shorter intensive care unit stay, a shorter duration of postoperative fasting and a shorter duration of an indwelling nasogastric tube. Therefore, unless there is any contraindication for a retroperitoneal approach, it could be considered as a primary surgical access for repairing an abdominal aortic aneurysm.

• Journal of Gastric Cancer
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• v.6 no.2
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• pp.84-90
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• 2006

Purpose: The macroscopic findings of tumors are not always identical with the microscopic findings. This study investigated the oncologic implications of macroscopic serosal invasion in advanced gastric cancer to find out how to improve the accuracy for the depth of invasion assessed by the surgeon during an operation. Materials and Methods: The medical records of 789 patients with advanced gastric cancer who underwent a gastrectomy at Kyungpook National University Hospital between 1995 and 1999 were reviewed. The prognoses and the recurrence patterns were analyzed according to macroscopic serosal invasion and microscopic serosal invasion, and the clinico-pathological factors of cT3/ss cancers were compared with those of cT3/se cancers. Results: Difference of survival rates according to macroscopic serosal invasion and microscopic serosal invasion revealed statistically significant. Recurrence rates were similar in patients with macroscopic and microscopic serosal invasion (42.2% and 41.4%, respectively). Peritoneal recurrence rates were also similar (19.8% and 21.9%, respectively). The sensitivity and the specificity of macroscopic assessment of serosal invasion were 70.3% and 77.8%, respectively, On univariate and multivariate analyses, Borrmann type I/II cancers and the absence of distant metastases revealed the risk factors for overestimating of serosal invasion. Conclusion: Macroscopic serosal invasion assessed by a surgeon intraoperatively can be used to give a prognosis and to predict the recurrence pattern precisely, although there is a risk for overestimation when the tumor is a Borrmann type I/II cancer or the tumor has no distant metastases. (J Korean Gastric Cancer Assoc 2006;6:84-90)

• Economic and Environmental Geology
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• v.55 no.4
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• pp.353-366
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• 2022

Spatial estimation of geoscience data (geo-data) is challenging due to spatial heterogeneity, data scarcity, and high dimensionality. A novel spatial estimation method is needed to consider the characteristics of geo-data. In this study, we proposed the application of Gaussian Mixture Model (GMM) among machine learning algorithms with multivariate data for robust spatial predictions. The performance of the proposed approach was tested through soil chemical concentration data from a former smelting area. The concentrations of As and Pb determined by ex-situ ICP-AES were the primary variables to be interpolated, while the other metal concentrations by ICP-AES and all data determined by in-situ portable X-ray fluorescence (PXRF) were used as auxiliary variables in GMM and ordinary cokriging (OCK). Among the multidimensional auxiliary variables, important variables were selected using a variable selection method based on the random forest. The results of GMM with important multivariate auxiliary data decreased the root mean-squared error (RMSE) down to 0.11 for As and 0.33 for Pb and increased the correlations (r) up to 0.31 for As and 0.46 for Pb compared to those from ordinary kriging and OCK using univariate or bivariate data. The use of GMM improved the performance of spatial interpretation of anthropogenic metals in soil. The multivariate spatial approach can be applied to understand complex and heterogeneous geological and geochemical features.

• The Korean Journal of Applied Statistics
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• v.28 no.3
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• pp.407-415
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• 2015

$Na{\ddot{i}}ve$ Bayes Classification is based on input variables that are a conditionally independent given output variable. The $Na{\ddot{i}}ve$ Bayes assumption is unrealistic but simplifies the problem of high dimensional joint probability estimation into a series of univariate probability estimations. Thus $Na{\ddot{i}}ve$ Bayes classier is often adopted in the analysis of massive data sets such as in spam e-mail filtering and recommendation systems. In this paper, we propose a variable selection method based on ${\chi}^2$ statistic on input and output variables. The proposed method retains the simplicity of $Na{\ddot{i}}ve$ Bayes classier in terms of data processing and computation; however, it can select relevant variables. It is expected that our method can be useful in classification problems for ultra-high dimensional or big data such as the classification of diseases based on single nucleotide polymorphisms(SNPs).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.363-368
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• 1993

Short-term forecasting of fish catch is of practical importance in fisheries management. Ecosystem models and multi-species models as well as traditional single-species models fall short of predicting power needed for practical management of fisheries resources due to the lack of sufficient data or information for the required parameters. Univariate time series analysis, on the other hand, extracts the information on the stochastic variability from the time series itself and makes estimates of the future stochastic variability. Therefore, it can be used for short-term forecasting with minimum data requirements. ARIMA time series modeling has been applied to the monthly Korean catches of hairtail (Trichiurus lepturus) for $1971{\sim}1988$. Forecasts of hairtail catch were made and compared with the actual catch data from $1989{\sim}1990$ which were not included in the parameter estimation. The results showed a good agreement (r=0.938) between the forecasts and the actual catches with a mean rotative error of $59.5\%$

• Korean Journal of Head & Neck Oncology
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• v.7 no.2
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• pp.104-113
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• 1991

선양낭암은 타액선종양중 비교적 드문 악성종양으로 병리조직학적 및 임상적으로 독특한 양상을 보인다. 병리조직학상 종양세포가 신경주변으로 침범하여 수술당시 적절한 수술연을 얻기 어렵고 이에 따른 국소재발이 거듭되고 임파선전이 및 예측치 않는 원격전이가 생기기도 한다. 지금까지 선양낭암환자의 예후에 영향을 미치는 여러 요인들에 대한 연구들이 이루워지고 있는데 그중 조직학적 분화도, 원발부위, 종양의 크기, 수술연의 상태와 임상적 병기들이 중요시되고 있다. 이에 저자들은 1960년부터 1980년 까지 텍사스대학 M.D. Anderson 암센터에서 치료받은 이하선 및 악하선 선양낭암 각각 13례와 26례를 대상으로 원발부위가 환자의 생존 및 치료에 미치는 영향을 알고자 다른 예후인자로 알려진 조직병리학적 소견들과 함께 통계학적 분석을 실시하였다. 이하선과 악하선에 생긴 선양낭암을 비교한 결과 이하선에 생긴 경우 조직학적 분화도가 더 낮았고 악하선 종양에서 수술연에 종양침범율이 더 적었다. 경부 임파절 전이는 악하선 종양에서 많았으나 반면 원격전이는 이하선 종양에서 더 많이 발생하였다. 그러나 종양의 크기, 선경주위침범 유무, 국소재발과 환자의 생존율사이에는 의의있는 상관 관계는 없었다. 이하선과 악하선에 생긴 선양낭암의 여러 특성들과 생존률간의 univariate 분석결과 악하선에 생긴 선양낭암 환자에서 종양이 크거나 조직학상 분화가 나쁘거나(solid pattern), 경부임파절 전이와 원격전이가 생기면 예후에 나쁜 영향을 끼침이 밝혀졌다. 그러나 이하선에 생긴 경우 분석례가 너무 적어 결론을 내리기에 불충분하였다. 원발부위에 따른 선양낭암 환자들의 특성을 chi-square 검정법을 이용하여 통계학적으로 분석한 결과 이 두군간에는 의의있는 통계학적 차이는 발견할 수 없었다.

• Journal of Korea Water Resources Association
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• v.37 no.11
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• pp.915-927
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• 2004

The purpose of this paper is to estimate the instream flow of the South Han River Basin to ensure an adequate supply of suitable quality of water for preservation and enhancement of aquatic ecosystems. Proposed methods is Physical Habitant Simulation System of Instream Flow Incremental Methodology. Accurate estimation on a water depth and a velocity distribution was acquired by applying a two dimensional hydrodynamic model for a simulation of a hydraulic parameter necessary for the habitat evaluation to be used in a physical habitat simulation system. The Habitat Suitability Criteria with the application of univariate curve on zacco platypus as a representative fish was able to be established by conducting a field investigation. The establishment of a hydrological materialistic balance between upper and lower streams was confirmed by conducting a simulation simultaneously together with a mainstream section, which was excluded from the considered sections for the inhabitation evaluation of fish.