• Journal of Korean Society of Water and Wastewater
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• v.30 no.1
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• pp.41-49
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• 2016

In this study, rainfall characteristics with stationary and non-stationary perspectives were analyzed using generalized extreme value (GEV) distribution and Gumbel distribution models with rainfall data collected in major cities of Korea to reevaluate the return period of sewer flooding in those cities. As a result, the probable rainfall for GEV and Gumbel distribution in non-stationary state both increased with time(t), compared to the stationary probable rainfall. Considering the reliability of ${\xi}_1$, a variable reflecting the increase of storm events due to climate change, the reliability of the rainfall duration for Seoul, Daegu, and Gwangju in the GEV distribution was over 90%, indicating that the probability of rainfall increase was high. As for the Gumbel distribution, Wonju, Daegu, and Gwangju showed the higher reliability while Daejeon showed the lower reliability than the other cities. In addition, application of the maximum annual rainfall change rate (${\xi}_1{\cdot}t$) to the location parameter made possible the prediction of return period by time, therefore leading to the evaluation of design recurrence interval.

• Radiation Oncology Journal
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• v.36 no.2
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• pp.139-146
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• 2018

Purpose: IBTR! 2.0 nomogram is web-based nomogram that predicts ipsilateral breast tumor recurrence (IBTR). We aimed to validate the IBTR! 2.0 using an external data set. Materials and Methods: The cohort consisted of 2,206 patients, who received breast conserving surgery and radiation therapy from 1992 to 2012 at our institution, where wide surgical excision is been routinely performed. Discrimination and calibration were used for assessing model performance. Patients with predicted 10-year IBTR risk based on an IBTR! 2.0 nomogram score of <3%, 3%-5%, 5%-10%, and >10% were assigned to groups 1, 2, 3, and 4, respectively. We also plotted calibration values to observe the actual IBTR rate against the nomogram-derived 10-year IBTR probabilities. Results: The median follow-up period was 73 months (range, 6 to 277 months). The area under the receiver operating characteristic curve was 0.607, showing poor accordance between the estimated and observed recurrence rate. Calibration plot confirmed that the IBTR! 2.0 nomogram predicted the 10-year IBTR risk higher than the observed IBTR rates in all groups. High discrepancies between nomogram IBTR predictions and observed IBTR rates were observed in overall risk groups. Compared with the original development dataset, our patients had fewer high grade tumors, less margin positivity, and less lymphovascular invasion, and more use of modern systemic therapies. Conclusions: IBTR! 2.0 nomogram seems to have the moderate discriminative ability with a tendency to over-estimating risk rate. Continued efforts are needed to ensure external applicability of published nomograms by validating the program using an external patient population.

• Radiation Oncology Journal
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• v.18 no.4
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• pp.300-308
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• 2000

Purpose :The aim of this study is to analysis of suwival and recurrence rates of the uterine cervical carcinoma patients whom received the radiation therapy respectively. The prognostic factors, such as Papanicolaou (Pap) smear, carcinoembriogenic antigen (CEA) and squamous cell carcinoma (SCC) antigen has been studied. Methods and Materials : From January 1981 to December 1998, eight-hundred twenty-seven uterine carvical cancer patients were treat with radiation therapy. All of the patients were divided into two groups : the radiation therapy only (S2l patients) group and the postoperative radiation therapy (326 patients) group. The age, treatment modality, clinical stage, histopathology, recurrence, follow-up Pap smears, CEA and SCC antigen were used as parameters for the evaluation. The prognostic factors such as survival and recurrence rates were peformed with the Kaplan-Meier method and the Cox hazard model, respectively. Median rollow-up was 38.6 months. Results :On the radiation therapy only group, 314 patients (60$\%$) achieved complete response (CR), 47 patients (9$\%$) showed local recurrence (LR), 78 patients (15$\%$) developed distant metastasis (DM). On the Postoperative radiation therapy group, showed 276 Patients (85$\%$) CR, 8 Patients (2$\%$) LR, 37 Patients (11$\%$) DM. The 5-year survival and recurrence rates was evaluated for all parameters. The statistically significant factors for the survival rate in univariate analysis were clinical stage (p=0.0001), treatment modality (p=0.0010), recurrence (p=0.0001), Pap smear (p=0.0329), CEA (p=0.0001) and SCC antigen (p=0.0001). Conclusion: This study indicated that after treatment, the follow-up studies of Pap smear, CEA and SCC antigen were significant parameter and prediction factors for the survival and recurrence of the uterine cervical carcinoma.

• Journal of Korea Entertainment Industry Association
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• v.4 no.4
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• pp.72-76
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• 2010

Clinical nomogram is a graphical representation of numeric formula, constructed from clinical cases database of followed patients' treatment, which is used for medical predication. For a clinical nomogram to contribute patient care, it is required to accumulate as many as clinical cases and to extract medical prediction knowledge. It needs to be equipped with an effective method to build medical nomogram with high predication accuracy. It is desirable for medical nomogram to be accessible at patient care point. This paper proposes a medical nomogram service system architecture which takes into account the above-mentioned issues. The proposed system architecture includes a web-based database subsystem to maintain and keep track of clinical cases. On the periodic basis, a new clinical nomogram is reconstructed for the updated clinical database. For the convenient use of patient care practice environment, an app-based program is provided which makes prediction based on the most recent clinical nomogram constructed in the service system. The proposed method has been applied to a clinical nomogram service system development for recurrence and survival prediction in bladder cancer patients.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.5
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• pp.326-333
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• 2009

Design life-time of a wind turbine is required to be at least 20 years. In the meantime, the wind turbine will experience a lot of load cases such as extreme loads and fatigue loads which will include several typhoons per year and extreme gusts with 50 years recurrence period as well as endless turbulence flow. Therefore, IEC61400-1 specifies design load cases to be considered in the wind turbine design and requires the wind turbine to withstand the load cases in various operational situations. This paper investigates the ultimate loads which the wind turbine will experience for 20 years and their characteristics based on the IEC61400-1 using an aero-elastic software, GH-Bladed. And the performance characteristics of a wind turbine such as electrical power generation and annual energy yield are also investigated.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2880-2885
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• 2008

Design lifttime of a wind turbine is required to be at least 20 years. In the meantime, the wind turbine will experience a lot of load cases such as extreme loads and fatigue loads which will include several typhoons per year and extreme gusts with 50 years recurrence period as well as endless turbulence flow. Therefore, IEC61400-1 specifies design load cases to be considered in the wind turbine design and requires the wind turbine to withstand the load cases in various operational situations. This paper investigates the ultimate loads which the wind turbine will experience for 20 years and their characteristics based on the IEC61400-1 using an aero-elastic software, GH-Blade. And the performance characteristics of a wind turbine such as electrical power generation and annual energy yield are also investigated.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.87-89
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• 2013

이 논문에서는 비침윤성 방광암 환자의 재발 예측을 위해 마이크로어레이 데이터에서 최적의 속성 부분 집합을 찾고 이를 비교 평가한다. 정보 이득(information gain)을 통해 구한 상위 40개, 80개, 100개의 속성 집합과 FCBF(fast correlation based filter) 알고리즘을 적용하여 구한 최적의 속성 부분집합을 SVM 분류 모델에 적용하여 정확도를 비교 평가한 결과 정보 이득을 적용한 상위 100개 속성 부분집합의 분류 정확도가 가장 높게 나왔으며, FCBF 알고리즘을 적용한 속성 집합은 비교적 적은 속성을 사용하면서 이와 비슷한 분류 정확도를 보임을 확인할 수 있었다.

• Journal of Korea Water Resources Association
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• v.46 no.5
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• pp.439-447
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• 2013

The applicability of the parameter map of the Modified Bartlett-Lewis Rectangular Pulse (MBLRP) model for the Korean Peninsula was assessed from the perspective of flood prediction. The design rainfalls estimated from the MBLRP model were smaller than those from observed values by 5% to 40%, and the degree of underestimation of design rainfall increases with the increase of the recurrence interval of the design rainfall. The design floods at a virtual watershed estimated using the simulated rainfall time series based on MBLRP model were also smaller than those derived from the observed rainfall time series by 20% to 45%. The degree of underestimation of design flood increases with the increase of the recurrence interval of the design flood.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.4
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• pp.205-210
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• 2006

Purpose: FDG uptake on positron omission tomography (PET) has been considered a prognostic indicator in non-small cell lung cancer (NSCLC). The aim of this study was to assess the clinical significance of maximum value of SUV (maxSUV) in recurrence prediction in patients with surgically resected NSCLC. Materials & methods: NSCLC patients (n=42, F:M =14:28, age $62.3{\pm}12.3$ y) who underwent curative resection after FDG-PET were enrolled. Twenty-nine patients had pathologic stage 1, and 13 had pathologic stage II. Thirty-one patients were additionally treated with adjuvant oral chemotherapy. MaxSUVs of primary tumors were analyzed for correlation with tumor recurrence and compared with pathologic or clinical prognostic indicators. The median follow-up duration was 16 mo (range, 3-26 mo). Results: Ten (23.8%) of the 42 patients experienced recurrence during a median follow-up of 7.5 mo (range, 3-13 mo). Univariate analysis revealed that disease-free survival (DFS) was significantly correlated with maxSUV (<7 vs. $\geq7$, p=0.006), tumor size (<3 cm vs. $\geq3$ cm, p=0.024), and tumor tell differentiation (well/moderate vs. poor, p=0.044). However, multivariate Cox proportional analysis identified maxSUV as the single determinant for DFS (p=0.014). Patients with a maxSUV of $\geq7$(n=10) had a significantly lower 1-year DFS rate (50.0%) than those with a maxSUV of <7 (n=32, 87.5%). Conclusion: MaxSUV is a significant independent predictor for recurrence in surgically resected NSCLC. FDG uptake can be added to other well-known factors in prognosis prediction of NSCLC.

• Korean Journal of Radiology
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• v.24 no.3
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• pp.190-203
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• 2023

Objective: We aimed to assess and validate the radiologic and clinical factors that were associated with recurrence and survival after curative surgery for heterogeneous targetoid primary liver malignancies in patients with chronic liver disease and to develop scoring systems for risk stratification. Materials and Methods: This multicenter retrospective study included 197 consecutive patients with chronic liver disease who had a single targetoid primary liver malignancy (142 hepatocellular carcinomas, 37 cholangiocarcinomas, 17 combined hepatocellular carcinoma-cholangiocarcinomas, and one neuroendocrine carcinoma) identified on preoperative gadoxetic acid-enhanced MRI and subsequently surgically removed between 2010 and 2017. Of these, 120 patients constituted the development cohort, and 77 patients from separate institution served as an external validation cohort. Factors associated with recurrence-free survival (RFS) and overall survival (OS) were identified using a Cox proportional hazards analysis, and risk scores were developed. The discriminatory power of the risk scores in the external validation cohort was evaluated using the Harrell C-index. The Kaplan-Meier curves were used to estimate RFS and OS for the different risk-score groups. Results: In RFS model 1, which eliminated features exclusively accessible on the hepatobiliary phase (HBP), tumor size of 2-5 cm or > 5 cm, and thin-rim arterial phase hyperenhancement (APHE) were included. In RFS model 2, tumors with a size of > 5 cm, tumor in vein (TIV), and HBP hypointense nodules without APHE were included. The OS model included a tumor size of > 5 cm, thin-rim APHE, TIV, and tumor vascular involvement other than TIV. The risk scores of the models showed good discriminatory performance in the external validation set (C-index, 0.62-0.76). The scoring system categorized the patients into three risk groups: favorable, intermediate, and poor, each with a distinct survival outcome (all log-rank p < 0.05). Conclusion: Risk scores based on rim arterial enhancement pattern, tumor size, HBP findings, and radiologic vascular invasion status may help predict postoperative RFS and OS in patients with targetoid primary liver malignancies.