• 한국산업정보학회논문지
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• 제28권6호
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• pp.1-10
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• 2023

원전 계측제어계통은 정상운전 시 자가 진단기능의 유지보수를 위해 일정 주기로 건전성을 확인하고 있으며, 계획예방정비 기간 동안 기능 및 성능점검을 실시하여 필요한 경우 유지보수를 하고 있다. 하지만 원전의 정보를 계측하고 제어하는 계측제어계통에서도 선제적으로 고장을 진단하고 대처하여 사고전파를 방지할 수 있는 기술개발이 필요하다. 이에 본 논문에서는 계측제어 장비의 환경조건과 자가 진단 데이터를 활용한 신뢰도 함수 추정 방안을 연구하였으며, 고장데이터의 획득을 위해 계측제어 장비의 부품에 대한 Feature 별 확률분포를 가정하여 가상 고장데이터를 생산하였다. 이러한 고장데이터를 바탕으로 생존분석에서 활용되는 대표적인 인공지능 모델(DeepSurve, DeepHit)을 이용하여 신뢰도 함수를 추정하였고, 그와 동시에 전통적인 준모수적 방법론인 Cox 회귀모델을 통해 신뢰도 함수를 추정하여 환경조건과 진단 데이터를 바탕으로 한 잔여 수명 계산을 통해 적용 가능성을 확인하였다.

• Journal of Periodontal and Implant Science
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• 제54권1호
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• pp.44-52
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• 2024

Purpose: This study aimed to evaluate the clinical outcomes of a single type of narrow-diameter implant (NDI) by investigating its survival rate and peri-implant marginal bone loss (MBL). In addition, variables possibly related to implant survival and MBL were investigated to identify potential risk factors. Methods: The study was conducted as a retrospective study involving 49 patients who had received 3.0-mm diameter TSIII implants (Osstem Implant Co.) at Seoul National University Dental Hospital. In total, 64 implants were included, and dental records and radiographic data were collected from 2017 to 2022. Kaplan-Meier survival curves and a Cox proportional hazard model were used to estimate the implant survival rate and to investigate the effects of age, sex, jaw, implant location, implant length, the stage of surgery, guided bone regeneration, type of implant placement, and the surgeon's proficiency (resident or professor) on implant survival. The MBL of the NDIs was measured, and the factors influencing MBL were evaluated. Results: The mean observation period was 30.5 months (interquartile range, 26.75-45 months), and 6 out of 64 implants failed. The survival rate of the NDIs was 90.6%, and the multivariate Cox regression analysis showed that age was associated with implant failure (hazard ratio, 1.17; 95% confidence interval, 1.04-1.31, P=0.01). The mean MBL was 0.44±0.75 mm, and no factors showed statistically significant associations with greater MBL. Conclusions: NDIs can be considered a primary alternative when standard-diameter implants are unsuitable. However, further studies are required to confirm their long-term stability.

• The Journal of Advanced Prosthodontics
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• 제16권3호
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• pp.151-162
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• 2024

PURPOSE. This study aimed to analyze factors influencing the success and failure of implant prostheses and to estimate the lifespan of prostheses using standardized evaluation criteria. An online survey platform was utilized to efficiently gather large samples from multiple institutions. MATERIALS AND METHODS. During the one-year period, patients visiting 16 institutions were assessed using standardized evaluation criteria (KAP criteria). Data from these institutions were collected through an online platform, and various statistical analyses were conducted. Risk factors were assessed using both the Cox proportional hazard model and Cox regression analysis. Survival analysis was conducted using Kaplan-Meier analysis and nomogram, and lifespan prediction was performed using principal component analysis. RESULTS. The number of patients involved in this study was 485, with a total of 841 prostheses evaluated. The median survival was estimated to be 16 years with a 95% confidence interval. Factors found to be significantly associated with implant prosthesis failure, characterized by higher hazard ratios, included the 'type of clinic', 'type of antagonist', and 'plaque index'. The lifespan of implant prostheses that did not fail was estimated to exceed the projected lifespan by approximately 1.34 years. CONCLUSION. To ensure the success of implant prostheses, maintaining good oral hygiene is crucial. The estimated lifespan of implant prostheses is often underestimated by approximately 1.34 years. Furthermore, standardized form, online platform, and visualization tool, such as nomogram, can be effectively utilized in future follow-up studies.

• Korean Journal of Radiology
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• 제25권2호
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• pp.189-198
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• 2024

Objective: To investigate the prognostic utility of radiomics features extracted from ¹⁸F-fluorodeoxyglucose (FDG) PET/CT combined with clinical factors and metabolic parameters in predicting progression-free survival (PFS) and overall survival (OS) in individuals diagnosed with extranodal nasal-type NK/T cell lymphoma (ENKTCL). Materials and Methods: A total of 126 adults with ENKTCL who underwent ¹⁸F-FDG PET/CT examination before treatment were retrospectively included and randomly divided into training (n = 88) and validation cohorts (n = 38) at a ratio of 7:3. Least absolute shrinkage and selection operation Cox regression analysis was used to select the best radiomics features and calculate each patient's radiomics scores (RadPFS and RadOS). Kaplan-Meier curve and Log-rank test were used to compare survival between patient groups risk-stratified by the radiomics scores. Various models to predict PFS and OS were constructed, including clinical, metabolic, clinical + metabolic, and clinical + metabolic + radiomics models. The discriminative ability of each model was evaluated using Harrell's C index. The performance of each model in predicting PFS and OS for 1-, 3-, and 5-years was evaluated using the time-dependent receiver operating characteristic (ROC) curve. Results: Kaplan-Meier curve analysis demonstrated that the radiomics scores effectively identified high- and low-risk patients (all P < 0.05). Multivariable Cox analysis showed that the Ann Arbor stage, maximum standardized uptake value (SUVmax), and RadPFS were independent risk factors associated with PFS. Further, β2-microglobulin, Eastern Cooperative Oncology Group performance status score, SUVmax, and RadOS were independent risk factors for OS. The clinical + metabolic + radiomics model exhibited the greatest discriminative ability for both PFS (Harrell's C-index: 0.805 in the validation cohort) and OS (Harrell's C-index: 0.833 in the validation cohort). The time-dependent ROC analysis indicated that the clinical + metabolic + radiomics model had the best predictive performance. Conclusion: The PET/CT-based clinical + metabolic + radiomics model can enhance prognostication among patients with ENKTCL and may be a non-invasive and efficient risk stratification tool for clinical practice.

• Asian Pacific Journal of Cancer Prevention
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• 제15권1호
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• pp.185-190
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• 2014

Influence of loneliness on human survival has been established epidemiologically, but genomic research remains undeveloped. We identified 34 loneliness-associated genes which were statistically significant for high-lonely and low-lonely individuals. With the univariate Cox proportional hazards regression model, we obtained corresponding regression coefficients for loneliness-associated genes fo individual cancer patients. Furthermore, risk scores could be generated with the combination of gene expression level multiplied by corresponding regression coefficients of loneliness-associated genes. We verified that high-risk score cancer patients had shorter mean survival time than their low-risk score counterparts. Then we validated the loneliness-associated gene signature in three independent brain cancer cohorts with Kaplan-Meier survival curves (n=77, 85 and 191), significantly separable by log-rank test with hazard ratios (HR) >1 and p-values <0.0001 (HR=2.94, 3.82, and 1.78). Moreover, we validated the loneliness-associated gene signature in bone cancer (HR=5.10, p-value=4.69e-3), lung cancer (HR=2.86, p-value=4.71e-5), ovarian cancer (HR=1.97, p-value=3.11e-5), and leukemia (HR=2.06, p-value=1.79e-4) cohorts. The last lymphoma cohort proved to have an HR=3.50, p-value=1.15e-7. Loneliness-associated genes had good survival prediction for cancer patients, especially bone cancer patients. Our study provided the first indication that expression of loneliness-associated genes are related to survival time of cancer patients.

• Journal of Gastric Cancer
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• 제17권4호
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• pp.319-330
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• 2017

Introduction: The extent of lymphadenectomy in the surgical treatment of gastric cancer is a topic of controversy among surgeons. This study was conducted to analyze the American National Cancer Database (NCDB) and conclude the optimal extent of lymphadenectomy for gastric adenocarcinoma. Methods: The NCDB for gastric cancer was utilized. Patients who received at least a partial gastrectomy were included. Patients with metastatic disease, unknown TNM stages, R1/R2 resection, or treated with a palliative intent were excluded. Joinpoint regression was used to identify the extent of lymphadenectomy that reflects the optimal survival. Cox regression analysis and Bayesian information criterion were used to identify significant survival predictors. Kaplan-Meier was applied to study overall survival and stage migration. Results: 40,281 patients of 168,377 met the inclusion criteria. Joinpoint analysis showed that dissection of 29 nodes provides the optimal median survival for the overall population. Regression analysis reported the cutoff ${\geq}29$ to have a better fit in the prognostic model than that of ${\geq}15$. Dissection of ${\geq}29$ nodes in the higher stages provides a comparable overall survival to the immediately lower stage. Nonetheless, the retrieval of ${\geq}15$ nodes proved to be adequate for staging without a significant stage migration compared to ${\geq}29$ nodes. Conclusion: The extent of lymphadenectomy in gastric adenocarcinoma is a marker of improved resection which reflects in a longer overall survival. Our analysis concludes that the dissection of ${\geq}15$ nodes is adequate for staging. However, the dissection of 29 nodes might be needed to provide a significantly improved survival.

• Journal of Microbiology and Biotechnology
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• 제34권5호
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• pp.1164-1177
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• 2024

Esophageal squamous cell carcinoma (ESCC) is among the most common malignant tumors of the digestive tract, with the sixth highest fatality rate worldwide. The ESCC-related dataset, GSE20347, was downloaded from the Gene Expression Omnibus (GEO) database, and weighted gene co-expression network analysis was performed to identify genes that are highly correlated with ESCC. A total of 91 transcriptome expression profiles and their corresponding clinical information were obtained from The Cancer Genome Atlas database. A mitochondria-associated risk (MAR) model was constructed using the least absolute shrinkage and selection operator Cox regression analysis and validated using GSE161533. The tumor microenvironment and drug sensitivity were explored using the MAR model. Finally, in vitro experiments were performed to analyze the effects of hub genes on the proliferation and invasion abilities of ESCC cells. To confirm the predictive ability of the MAR model, we constructed a prognostic model and assessed its predictive accuracy. The MAR model revealed substantial differences in immune infiltration and tumor microenvironment characteristics between high- and low-risk populations and a substantial correlation between the risk scores and some common immunological checkpoints. AZD1332 and AZD7762 were more effective for patients in the low-risk group, whereas Entinostat, Nilotinib, Ruxolutinib, and Wnt.c59 were more effective for patients in the high-risk group. Knockdown of TYMS significantly inhibited the proliferation and invasive ability of ESCC cells in vitro. Overall, our MAR model provides stable and reliable results and may be used as a prognostic biomarker for personalized treatment of patients with ESCC.

• 한국사회복지학
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• 제59권1호
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• pp.301-327
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• 2007

본 연구의 목적은 미국에서 친권상실이 선고된 위탁아동의 입양률 추이를 살펴보고, 입양결정에 영향을 미치는 주된 요인을 규명하는 데 있다. 본 연구는 미국 위탁보호와 입양에 관한 패널데이터 FY1999-FY2002를 이용하여 1998년 10월부터 2002년 9월까지 32개 주를 추출하여 총 26,895명을 분석에 활용하였다. 사건사 분석의 Kaplan-Meier 분석과 비례적 위험회귀모형(Cox proportional hazards regression model)을 이용하여 친권상실선고 이후 소요되는 위탁기간에 따른 입양률 추이와 위험 입양배율(hazard ratios for adoption)를 산출하였다. 본 연구의 주요 결과로는 친권상실선고 이후 3개월-19개월까지 입양률이 급속히 증가하다가 20개월이 지나면서 오히려 감소추세를 보이고 있었다. 입양여부와 관련한 주요 요인으로서는 백인아동일 경우, 나이가 어릴수록, 선입양가족, 도시소재의 위탁보호일 경우, 양부모 위탁가족, 또는 인종적으로 동일한 위탁부모에 의해 위탁보호 될 경우 입양가능성이 상대적으로 높게 나타났다. 또한, 아동이 지체나 장애가 있을 경우, 신체학대나 성학대를 경험한 경우, 친부모의 양육능력부족으로 위탁보호 된 경우 상대적으로 낮은 입양가능성을 보이고 있다. 본 연구결과 친권상실 이전에 발생한 위탁보호 원인이 친권상실 이후에도 입양에 영향을 미치고 있으며, 입양촉진방안으로 친권상실선고 이후 제공된 위탁서비스 활용과 적극적 지원방안 모색의 필요성이 제기되었다. 끝으로 본 연구결과를 바탕으로 한국사회에서 요보호아동의 친권개입의 정책적 방향과 항구적 보호마련을 위한 함의와 제언을 개괄적으로 제시하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.5095-5099
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• 2015

Background: The statistical methods to analyze and predict the related dangerous factors of deep fungal infection in lung cancer patients were several, such as logic regression analysis, meta-analysis, multivariate Cox proportional hazards model analysis, retrospective analysis, and so on, but the results are inconsistent. Materials and Methods: A total of 696 patients with lung cancer were enrolled. The factors were compared employing Student's t-test or the Mann-Whitney test or the Chi-square test and variables that were significantly related to the presence of deep fungal infection selected as candidates for input into the final artificial neural network analysis (ANN) model. The receiver operating characteristic (ROC) and area under curve (AUC) were used to evaluate the performance of the artificial neural network (ANN) model and logistic regression (LR) model. Results: The prevalence of deep fungal infection from lung cancer in this entire study population was 32.04%(223/696), deep fungal infections occur in sputum specimens 44.05%(200/454). The ratio of candida albicans was 86.99% (194/223) in the total fungi. It was demonstrated that older (${\geq}65$ years), use of antibiotics, low serum albumin concentrations (${\leq}37.18g/L$), radiotherapy, surgery, low hemoglobin hyperlipidemia (${\leq}93.67g/L$), long time of hospitalization (${\geq}14$days) were apt to deep fungal infection and the ANN model consisted of the seven factors. The AUC of ANN model($0.829{\pm}0.019$)was higher than that of LR model ($0.756{\pm}0.021$). Conclusions: The artificial neural network model with variables consisting of age, use of antibiotics, serum albumin concentrations, received radiotherapy, received surgery, hemoglobin, time of hospitalization should be useful for predicting the deep fungal infection in lung cancer.

• Journal of Hospice and Palliative Care
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• 제18권1호
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• pp.51-59
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• 2015

목적: 말기암환자의 진료에 있어 여명을 예측하는 것은 매우 중요한 문제이다. 여러 악성 종양에서 혈청 ferritin이 증가되어 있고 높은 수치의 혈청 ferritin은 질병의 진행 및 나쁜 예후와 관련이 있다고 밝혀져 있으므로 본 연구에서는 말기암환자에서 ferritin과 생존기간과의 연관성을 알아보고 혈청 ferritin이 여명 예측 인자로 유용한지 검증하고자 하였다. 방법: 2012년 3월부터 2012년 6월까지 완화병동에 입원한 말기암환자 65명을 대상으로 혈청 ferritin을 포함한 기본적인 혈액검사를 시행하였고, 인구 통계학적 특성 및 임상증상 등을 조사하였다. 혈청 ferritin과 각 변수들간의 관련성을 파악하기 위해 Spearman's correlation analysis, Wilcoxon Rank Sum test 또는Kruskal-Wallis test등을 실시하였고 혈청 ferritin의 예후인자로서의 유용성을 평가하기 위해 다변수 콕스 비례위험 회귀분석(multivariable Cox's proportional hazard regression analysis)을 시행하였다. 결과: 상관 관계 분석 결과 ferritin은 생존기간과 유의한 음의 상관관계를 보였다. 단변량 분석에서 생존기간에 유의한 영향을 미치는 성별, ECOG 기능상태 지수, 크레아티닌, 백혈구 수치와 나이의 효과를 보정한 상태에서 혈청 ferritin은 말기암환자들의 생존기간과 통계적으로 유의한 관계를 나타내었다. 결론: 짧은 생존기간의 말기암환자에서도 혈청 ferritin은 독립적인 예후인자로 증명되었다. 기존의 여명 예측인자들과 더불어, 혈청 ferritin은 말기암환자들의 생존기간 예측에 도움을 줄 수 있을 것이라 생각한다.