• Journal of Gastric Cancer
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• 제23권2호
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• pp.355-364
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• 2023

Background: There are no clear guidelines to determine whether to perform D1 or D1+ lymph node dissection in early gastric cancer (EGC). This study aimed to develop a nomogram for estimating the risk of extraperigastric lymph node metastasis (LNM). Materials and Methods: Between 2009 and 2019, a total of 4,482 patients with pathologically confirmed T1 disease at 6 affiliated hospitals were included in this study. The basic clinicopathological characteristics of the positive and negative extraperigastric LNM groups were compared. The possible risk factors were evaluated using univariate and multivariate analyses. Based on these results, a risk prediction model was developed. A nomogram predicting extraperigastric LNM was used for internal validation. Results: Multivariate analyses showed that tumor size (cut-off value 3.0 cm, odds ratio [OR]=1.886, P=0.030), tumor depth (OR=1.853 for tumors with sm2 and sm3 invasion, P=0.010), cross-sectional location (OR=0.490 for tumors located on the greater curvature, P=0.0303), differentiation (OR=0.584 for differentiated tumors, P=0.0070), and lymphovascular invasion (OR=11.125, P<0.001) are possible risk factors for extraperigastric LNM. An equation for estimating the risk of extraperigastric LNM was derived from these risk factors. The equation was internally validated by comparing the actual metastatic rate with the predicted rate, which showed good agreement. Conclusions: A nomogram for estimating the risk of extraperigastric LNM in EGC was successfully developed. Although there are some limitations to applying this model because it was developed based on pathological data, it can be optimally adapted for patients who require curative gastrectomy after endoscopic submucosal dissection.

• 한국지반공학회지:지반
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• 제7권3호
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• pp.43-50
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• 1991

굴착 중 slurry로 지대되고 있는 상태에서 지하수와 상재하중의 영향을 고려한 diaphragm wall 의 안정도를 해석하기 위하여 Belt Piaskowski/kowalewski, Washbourne의 모델을 확장하고, 확장된 이론으로 프로그램 SL3D를 개발하였다. Washbourne의 모델에서는 Bell, Piaskowski / Kowalewski의 모델에 비해, 굴착깊이가 증가함에 따라 안정도가 매우 큰 폭으로 증가하고, 비교적 초기굴착단계에서 부터 안전측에 속한다. 또한 slurry의 밀도, 지하수위, 흙의 내부마찰각, trench의 길이,상재단위하중등이 안정도에 미치는 영향을 분석하였고, 이것을 근거로 nomogram을 작성하였다.

• 한국해안해양공학회지
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• 제8권3호
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• pp.236-245
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• 1996

심해파가 천이수역 또는 천해로 이동하여 올 때 수심의 변화에 의해 발생하는 파의 굴절을 울산만 해역에서 수치모델을 이용하여 분석하여 보았다. 또한 이 모델은 해안 또는 연안의 어 특정한 지점에서 풍향 및 풍속 자료를 이용하여 파랑스책트럼을 계산할 수 있으며, 이로부터 그 지점에서의 유의파고를 구할 수 있다. 본 연구에서는 임의의 일정한 풍향과 풍속을 토대로 파랑스책트럼을 계산하였으며, 그 결과를 PNJ(Pierson, Newmann and James) 계산도표 및 Bretschneider 계산도표와 비교하여 보았다. 이러한 굴절과 파랑스책트럼은 항만 선정이나 각종 해안구조물 설계 등에 있어 기초자료로 유용하게 쓰일 수 있을 것이다

• 전산구조공학
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• 제7권1호
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• pp.99-107
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• 1994

감쇠재료인 점탄성재료는 여러 산업현장에서 발생하는 소음 및 진동문제를 해결하기 위하여 널리 쓰이고 있다. 기존의 진동감쇠 제어기술을 이용하여 이러한 문제를 성공적으로 해결하기 위해서는 먼저 제어하고자 하는 구조물에 적용될 점탄성재료의 진동감쇠 특성이 명확히 규명되어야 한다. 따라서 본 연구에서는 1)우리의 일반적인 실험실 환경에서 모우드해석법을 통해 점탄성재료의 진동감쇠특성을 측정할 수 있는 실험이론과 기법을 정립하고 2)제한된 환경(온도 및 주파수)에서 얻어진 실험 데이타를 이용하여 reduced-frequenct-nomogram(RFN)을 그릴 수 있는 전산프로그램을 개발하였으며 또한 RFN으로부터 확보한 점탄성재료의 진동감쇠특성을 이용하여 감쇠처리된 구조물의 진동해석을 수행하였다.

• 화약ㆍ발파
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• 제24권1호
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• pp.1-8
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• 2006

최근 대부분의 석회석 광산은 환경문제 등으로 인하여 노천채광에서 지하채굴로 전환되었다. 그 결과 노천채광과 같은 생산성을 유지하기 위해 갱도가 대형화되고 있다. 이에 따라 갱도 및 광주의 규모 그리고 굴착방법 등에서 많은 문제가 발생하고 있다. 본 연구는 두 갱도의 동시 발파 혹은 단일갱도 내에서 좌운반갱도와 사갱을 동시 발파, 두 갱도를 다단 발파 그리고 각각의 갱도를 단독 발파하여 굴착했을 때의 발파진동을 계측하여 각각의 굴착방법에 따라 발파진동식을 산출하여 노모그램 분석과 암반손상권 분석을 실시하였다.

• 대한임상검사과학회지
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• 제37권3호
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• pp.207-211
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• 2005

Body index is known as it affects pulmonary function tests (PFT), so it has been used with predictive formula and nomogram in terms of sex, age, height, etc. Body indices as body weight, body mass index (BMI), and body surface area (BSA) might also affect PFT, so that we have analyzed the correlations between body indices and forced expiratory volume in one second ($FEV_1$), and have done multiple regression analysis to see how body indices affect $FEV_1$. We confirmed that $FEV_1$ had positive correlations with height (r=0.49, p<0.01), body weight (r=0.37, p<0.01), and BSA (r=0.47, p<0.01), inverse correlation with age (r=-0.45, p<0.01), but no correlation with BMI. We found that the 41.9% of $FEV_1$ was diverged from height, age and BSA. Therefore, BSA definitely needs to be considered with predictive formula and nomogram in PFT.

• Asian Pacific Journal of Cancer Prevention
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• 제15권14호
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• pp.5721-5727
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• 2014

Objectives: To evaluate the performance of clustering methods used in the prognostic assessment of categorical clinical data for hepatocellular carcinoma (HCC) patients in China, and establish a predictable prognostic nomogram for clinical decisions. Materials and Methods: A total of 332 newly diagnosed HCC patients treated with hepatic resection during 2006-2009 were enrolled. Patients were regularly followed up at outpatient clinics. Clustering methods including the Average linkage, k-modes, fuzzy k-modes, PAM, CLARA, protocluster, and ROCK were compared by Monte Carlo simulation, and the optimal method was applied to investigate the clustering pattern of the indices including platelet count, platelet/lymphocyte ratio (PLR) and serum aspartate aminotransferase activity/platelet count ratio index (APRI). Then the clustering variable, age group, tumor size, number of tumor and vascular invasion were studied in a multivariable Cox regression model. A prognostic nomogram was constructed for clinical decisions. Results: The ROCK was best in both the overlapping and non-overlapping cases performed to assess the prognostic value of platelet-based indices. Patients with categorical platelet-based indices significantly split across two clusters, and those with high values, had a high risk of HCC recurrence (hazard ratio [HR] 1.42, 95% CI 1.09-1.86; p<0.01). Tumor size, number of tumor and blood vessel invasion were also associated with high risk of HCC recurrence (all p< 0.01). The nomogram well predicted HCC patient survival at 3 and 5 years. Conclusions: A cluster of platelet-based indices combined with other clinical covariates could be used for prognosis evaluation in HCC.

• 한국산학기술학회논문지
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• 제20권4호
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• pp.545-550
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• 2019

전 세계적으로 발생하고 있는 이상기후현상으로 자연재해의 발생빈도와 피해규모가 증가하고 있는 추세이다. 이로 인하여 도시유역의 수문학적 양상이 변화함에 따라 불투수 면적 증가와 함께 증가된 호우로 심각한 내수침수 피해를 가져온다. 이에 인명 및 재산피해를 최소화하기 위하여 내수침수 예측체계가 필요하다. 본 연구에서는 강우강도와 지속시간만으로 침수예측이 가능한 Flood Nomogram을 개발하였다. 내수침수 발생가능이 매우 높고 침수 위험도가 높은 대도시내 침수예상 지역의 내수침수피해 특성을 분석하여 내수침수 예보 기준을 설정하는 방법을 제시하였다. 또한 우수맨홀과 우수관경을 기준으로 내수위를 4가지 조건하에 도시내수침수 예보 기준을 다음과 같이 설정하였다. 1) 우수맨홀이 넘칠 때, 2) 우수관경이 가득 찼을 때, 3) 우수관경의 70%에 도달했을 때, 그리고 4) 우수관경의 60%에 도달했을 경우이다. 따라서, 침수가 발생하기 시작하는 강우와 침수피해를 유발하는 강우사상을 통하여, 내수침수가 시작되기 전에 사전대비, 대응할 수 있는 기준과 예측하는 수단으로 활용할 수 있을 것으로 나타났다.

• Korean Journal of Radiology
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• 제23권8호
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• pp.811-820
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• 2022

Objective: To develop a model incorporating radiomic features and clinical factors to accurately predict acute ischemic stroke (AIS) outcomes. Materials and Methods: Data from 522 AIS patients (382 male [73.2%]; mean age ± standard deviation, 58.9 ± 11.5 years) were randomly divided into the training (n = 311) and validation cohorts (n = 211). According to the modified Rankin Scale (mRS) at 6 months after hospital discharge, prognosis was dichotomized into good (mRS ≤ 2) and poor (mRS > 2); 1310 radiomics features were extracted from diffusion-weighted imaging and apparent diffusion coefficient maps. The minimum redundancy maximum relevance algorithm and the least absolute shrinkage and selection operator logistic regression method were implemented to select the features and establish a radiomics model. Univariable and multivariable logistic regression analyses were performed to identify the clinical factors and construct a clinical model. Ultimately, a multivariable logistic regression analysis incorporating independent clinical factors and radiomics score was implemented to establish the final combined prediction model using a backward step-down selection procedure, and a clinical-radiomics nomogram was developed. The models were evaluated using calibration, receiver operating characteristic (ROC), and decision curve analyses. Results: Age, sex, stroke history, diabetes, baseline mRS, baseline National Institutes of Health Stroke Scale score, and radiomics score were independent predictors of AIS outcomes. The area under the ROC curve of the clinical-radiomics model was 0.868 (95% confidence interval, 0.825-0.910) in the training cohort and 0.890 (0.844-0.936) in the validation cohort, which was significantly larger than that of the clinical or radiomics models. The clinical radiomics nomogram was well calibrated (p > 0.05). The decision curve analysis indicated its clinical usefulness. Conclusion: The clinical-radiomics model outperformed individual clinical or radiomics models and achieved satisfactory performance in predicting AIS outcomes.

• Korean Journal of Radiology
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• 제23권4호
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• pp.466-478
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• 2022

Objective: ¹⁸F-fluorodeoxyglucose (FDG) PET/CT is often used for detecting malignancy in patients with newly diagnosed hemophagocytic lymphohistiocytosis (HLH), with acceptable sensitivity but relatively low specificity. The aim of this study was to improve the diagnostic ability of ¹⁸F-FDG PET/CT in identifying malignancy in patients with HLH by combining ¹⁸F-FDG PET/CT and clinical parameters. Materials and Methods: Ninety-seven patients (age ≥ 14 years) with secondary HLH were retrospectively reviewed and divided into the derivation (n = 71) and validation (n = 26) cohorts according to admission time. In the derivation cohort, 22 patients had malignancy-associated HLH (M-HLH) and 49 patients had non-malignancy-associated HLH (NM-HLH). Data on pretreatment ¹⁸F-FDG PET/CT and laboratory results were collected. The variables were analyzed using the Mann-Whitney U test or Pearson's chi-square test, and a nomogram for predicting M-HLH was constructed using multivariable binary logistic regression. The predictors were also ranked using decision-tree analysis. The nomogram and decision tree were validated in the validation cohort (10 patients with M-HLH and 16 patients with NM-HLH). Results: The ratio of the maximal standardized uptake value (SUVmax) of the lymph nodes to that of the mediastinum, the ratio of the SUVmax of bone lesions or bone marrow to that of the mediastinum, and age were selected for constructing the model. The nomogram showed good performance in predicting M-HLH in the validation cohort, with an area under the receiver operating characteristic curve of 0.875 (95% confidence interval, 0.686-0.971). At an appropriate cutoff value, the sensitivity and specificity for identifying M-HLH were 90% (9/10) and 68.8% (11/16), respectively. The decision tree integrating the same variables showed 70% (7/10) sensitivity and 93.8% (15/16) specificity for identifying M-HLH. In comparison, visual analysis of ¹⁸F-FDG PET/CT images demonstrated 100% (10/10) sensitivity and 12.5% (2/16) specificity. Conclusion: ¹⁸F-FDG PET/CT may be a practical technique for identifying M-HLH. The model constructed using ¹⁸F-FDG PET/CT features and age was able to detect malignancy with better accuracy than visual analysis of ¹⁸F-FDG PET/CT images.