• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4367-4381
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• 2023

Nuclear power plants are increasingly being equipped with digital I&C systems. Although some probabilistic safety assessment (PSA) models for the digital I&C of nuclear power plants have been constructed, there is currently no specific internationally agreed guidance for their modeling. This paper presents an initiative by the OECD Nuclear Energy Agency called "Digital I&C PSA - Comparative application of DIGital I&C Modelling Approaches for PSA (DIGMAP)", which aimed to advance the field towards practical and defendable modeling principles. The task, carried out in 2017-2021, used a simplified description of a plant focusing on the digital I&C systems important to safety, for which the participating organizations independently developed their own PSA models. Through comparison of the PSA models, sensitivity analyses as well as observations throughout the whole activity, both qualitative and quantitative lessons were learned. These include insights on failure behavior of digital I&C systems, experience from models with different levels of abstraction, benefits from benchmarking as well as major contributors to the core damage frequency and those with minor effect. The study also highlighted the challenges with modeling of large common cause component groups and the difficulties associated with estimation of key software and common cause failure parameters.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.6
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• pp.205-212
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• 2006

In recent investigations, reinforced concrete beams strengthened with Carbon Fiber Sheets (CFS) subjected to fatigue loading were reported to be failed at the ends of CFS by its debonding. U-shaped CFS were attached to both ends of the CFS when fatigue tests on strengthened beams were conducted to delay and/or prevent fatigue failures of adhesive interface. The experimental parameters of this study were the usage of anchorage at the ends of CFS, the number of CFS layers, and the applied load levels of 60%~90% of the static ultimate load obtained from the static tests. The failure modes and the load cycle-deflection relations were observed and discussed from the experimental results. Those results also showed that the U-shaped anchoring system changes the fatigue failure modes and influences greatly on the fatigue capacity of the strengthened beams.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1417-1431
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• 1994

In this study, shear strength characteristics of the Nak-Dong river sand in Taegu area are investigated by triaxial compression test, considering shear strain control velocity, relative density, and confining pressure. The results from Lade model and Modified Lade model are compared with the measured value in the laboratory test. The results by the change of shear strain control velocity, relative density, and confining pressure are as follows; 1) The stress limit, which can be Coulomb's law about the Nak-Dong river sand, have ranged 120~200 kpa at 0.08%/min and 120~150 kpa at 0.5%/min. These limits are smaller than that of the calcareous sand and the well-graded, quartz sand. 2) The parameters needed to Lade model and Modified Lade model are much affected by the strain control velocity and the relative density. Consequently, in the field, it is important to use parameters aptly after accurately understanding both the loading condition and subsoil condition. 3) Overall, the principal stress ratio obtained from constitutive model equations is not affected by the control velocity, but both the relative density and confining pressure affect the result of constitutive model equations. Consequently, the study on the various conditions about the relative density and confining pressure is needed to accurately predict the stress-strain behavior on the Nak-Dong river sand. 4) For the range of the used confining pressure in the study, the Lade model shows better agreements with the measured value than the Modified Lade model, comparing the measured value with the principal stress ratio at failure and the internal friction angle of failure envelope obtained from the Lade model and Modified Lade model.

• Magazine of the Korea Concrete Institute
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• v.11 no.1
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• pp.149-160
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• 1999

This paper is a part of a research aimed at the verification of basic design rules of high-strength concrete columns. A total of 32 column specimens were tested to investigate structural behavior and strength of eccentrically loaded reinforced concrete tied columns. Main variables included in this test program were concrete compressive strength. steel amount, eccentricity, and slenderness ratio. The concrete compressive strength varied from 356 kg/$cm^2$ to 951 kg/$cm^2$ and the longitudinal steel ratios were between 1.13 % and 5.51 %. Test results of column sectional strength are compared with the results of analyses by ACI rectangular stress block, trapezoidal stress block, and modified rectangular stress block. Axial force-moment-curvature analysis is also performed for predicting axial load-moment strength and compared with the test results. The ACI rectangular stress block provides over-estimated column strengths for the lightly reinforced high strength column specimens. The calculated strengths by moment-curvature analyses are highly affected by $k_3$ values of the concrete stress-strain curve. Observed failure mode. concrete ultimate strain, and stress block parameters are discussed.

• Radiation Oncology Journal
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• v.11 no.1
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• pp.109-117
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• 1993

To analyze biochemical changes of liver function following combined radiotherapy and hyperthermia, we reviewed retrospectively 37 patients with hepatocellular carcinoma treated with radiotherapy and hyperthermia between July 1988 and December 1990 at Department of Radiation Oncology, Yonsei University College of Medicine. Mean age was 52.7 years and male to female ratio was 11:1. The patients were classified as follows; to A and B group by Child's classification, to M and L group by irradiated volume, and subclassified into BM, BL, AM and AL group according to the combination of Child's classification and irradiated volume. Radiation dose to the primary tumor was 3060 cGy with daily 180 cGy, 5 fraction per week using 10 MV or 4 MV linear accelerator. Hyperthermia (Thermotron RF-8) was performed more than 4 times in all patients. Biochemical parameters including albumin (Alb), total bilirubin (T. Bil), aspartate aminotransferase (AST or SGOT), alanine aminotransferase (ALT or SGPT), and alkaline phosphatase (ALP) were regularly followed from 1 week before the treatment to 3 months after the treatment. The results are summerized as follows; 1) In all the patient, mean ALP level peaked at 1 month, decreased at 2 months, slightly increased at 3 months after the treatment. Mean SGOT and SGPT levels peaked at 1 month after the treatment. Mean T. Bil level increased continuously and highest at 3 months after the treatment. Mean Alb level did not show significant changes.; 2) Mean ALP level retured to normal level at 3 month after the treatment in A but increased in B group and the differences were statistically significant (p<0.01). Mean SGOT and SGPT levels peaked 1 month in A and 2 months after the treatment in B group. All the biochemical parameters did not show significant difference between M and L group. Mean ALP level increased at 3 months after the treatment in BM and BL groups and decreased in AM and AL groups. Mean SGOT level increased at 3 months after the treatment in BL groups.; 3) Hepatic failure occurred within 3 months after the treatment in 4 patients, all of whom were in BL group. It is suggested that pre-treatment liver function and irradiated volume influence biochemical changes of liver in patients with hepatocellular carcinoma following combined radiotherapy and hyperthermia, and this treatment modality appears generally to be safe but might cause hepatic failure particularly in patient with poor liver function and large treatment volume.

• Journal of the Korean GEO-environmental Society
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• v.17 no.12
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• pp.55-64
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• 2016

In this paper bearing capacity and safety margin of shallow foundation on weathered soil ground against shear failure by using current design method of allowable stress design (ASD), load resistance factor design (LRFD) based on reliability analysis and partial safety factor design (PSFD) in Eurocode were estimated and compared to each other. Results of the plate loading test used in construction and design were collected and analysis of probability statistics on soil parameters affecting the bearing capacity of shallow foundation was performed to quantify the uncertainty of them and to investigate the resistance bias factor and covalence of ultimate bearing capacity. For the typical sections of shallow foundation in domestic field as examples, reliability index was obtained by reliability analysis (FORM) and the sensitivity analysis on soil parameters of probability variables was performed to investigate the effect of probability variable on shear failure. From stability analysis for these sections by ASD, LRFD with the target reiability index corresponding to the safety factor used in ASD and PSDF, safety margins were estimated respectively and compared.

• Journal of Chest Surgery
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• v.35 no.1
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• pp.1-10
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• 2002

Background: Despite the relatively high mortality rates in the chronic heart failure model induced by coronary artery ligation are relatively high, this model has been a subject of continuos research because of its clinical correlation. Chronic heart failure model of large-sized animals is very useful to analyse mechanical or biological effects on circulatory system which is difficult in small-sized animals. The purpose of this study is to establish the heart failure model by coronary artery ligation in sheep. Material and Method: Among 9 Corridale sheep, the homonymous artery and the diagonal branch were ligated simultaneously in 2 sheep and remaining 7 sheep were assigned to successive ligation of both arteries at an interval of 1 hour. Both coronary arteries were ligated from the point 40% proximal to the apex of the heart. Hemodynamic and echocardiographic parameters were analyzed before the ligation of the coronary artery, after the ligation of the homonymous artery, and after additional ligation of the diagonal branch. The experimental animals were sacrificed after 2 or 3 months of growth and histopathologic studies were performed Result: Immediate postoperative death occurred in the 2 sheep that had received simultaneous ligation of the homonymous artery and diagonal branch. On the other hand, all the 7 sheep that were lifated in succession were survived up to 3 months. Arterial pressure was sifnificantly decreased immediately after ligation of the homonymous artery(p<0.05), and the cardiac output was decreased and pulmonary capillary wedge pressure was increased after further ligation of the diagonal branch(p<0.05). Central venous pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, left ventricular end-diastolic dimension and end-systolic dimension were markedly increased 3 months after ligation of coronary arteries. Anteroseptal akinesia or dyskinesia was developed after the ligation of coronary arteries. Histopathologic study revealed we]1-demarcated ischemic area of fibrosis. Conclusion: Using methods of successive ligation of the homonymous artery and diagonal branch, chronic heart failure model could be reliably established in sheep.

• Radiation Oncology Journal
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• v.8 no.2
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• pp.241-253
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• 1990

331 patients of stage IIb uterine cervix cancer trated by radiation alone at Kosin Medical Center between June 1980 and Dec. 1985 were analysed to determine parameters of radiotherapy associated to disease states. Survival rate was highest among the reported ($82.8{\%}$ for crude and $82.4{\%}$ for disease free survival). Pelvic control rate in 6 weeks after the end of radiotherapy was $93.6{\%}$ in the patients treated with ICR following total pelvic radiation and $71.6{\%}$ with small field additional external irradiation. 5 year survival rate in those who achieved pelvic control was $98.9{\%}$ and $12.9{\%}$ in those who had pelvic failure and/or metastasis after radiation. The survival rate figured maximal $88.5{\%}$ with dosage of $7500{\~}8500$ cGy to point A with acceptable incidence of complications ($4.9{\%}$) but without increasing survival above it and minimal $74.1{\%}$ with dosage of less than 6500 cGy. The treatment failure was counted $18.7{\%}$ (62 of 331 patients): Local failure $72.6{\%}$ (45 of 62 patients), locoregional failure $3.2{\%}$ (2 of 62 patients) and distant failure $24{\%}$ (15 of 62 patients). Late complications were found in 50 patients ($15.1{\%}$) and $42{\%}$ of them was rectal bleeding and stenosis. The dose of 8500 cGy to point A was found to be critical for complication and $70{\%}$ of complications occurred above it and was more serious one such as fistula. Rectal complications were developed above rectal dose 6500 cGy and bladder complication above bladder dose 7500 cGy. Major cause of death was cachexia due to locoregional failure ($73.7{\%}$ of death), next was due to metastasis to lung, liver and bone, and only 3 patients died of complication of intestinal perforations and obstruction. In conclusion higher external radiation dose for a bulky uterine cervix and barrel shaped uterus was essential for local control.

• Childhood Kidney Diseases
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• v.1 no.1
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• pp.17-23
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• 1997

After the first description of IgA nephropathy by Berger in 1968, the prognosis of this disease was considered favourable. However recent studies have revealed that IgA nephropathy result in end stage renal desease in 25-30% by 20 years. Heavy proteinuria, hypertension, histological high class are regarded as poor prognostic factors. In 1996, Yagame et al reported the new histopathologic grading with a strong correlation between the grading, heavy proteinuria, high s-Cr level and renal survival. The aims of this study are to determine whether the pathological grading and other clinical parameters could contribute to predicting the outcome of this disease eventhough pediatric patients. Seventy nine patients (59 males, 20 females) with IgA nephropathy were examined. Patients were 2.08-15.17 years of age ($9.85{\pm}2.83$). The mean follow-up duration were $27{\pm}28$ months. Six of seventy nine patients progressed to chronic renal failure during the follow-up periods. High 24h urinary protein excretion at diagnosis were significantly higher in chronic renal failure patients (p<0.05). Hypertension at diagnosis were the significant associated factors in progression of chronic renal failure (p<0.05). Histological changes of IgA nephropathy in light microscopy were classified into five classes by WHO classification, four grades in Yagame's gradings. Among the seventy nine patients, 24 were as class 1, 30 as class 2, 23 as class 3; 4 as class 4, 0 as class 5 by WHO classification. 23 were classified grade 1, 31 as grade 2, 24 as grade 3, 1 as grade 4 by Yagame's grading. Among six patients who progressed to chronic renal failure, 1 clssified as class 1, 1 as class 2, 3 as class 3, 1 as class 4, 0 as class 5 by WHO Classification. 1 patients were classified as grade 1, 1 as grade 2, 3 as grade 3, 1 as grade 4 by Yagame's grading. (p>0.05) In conclusion, hypertension and heavy proteinuria at initial presentation were significantly associated with progression of chronic renal failure. The classification of WHO & Yagame's grading has no significant association with the progression of chronic renal failure in pediatric patients.

• Radiation Oncology Journal
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• v.33 no.2
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• pp.126-133
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• 2015

Purpose: To evaluate the outcomes of adjuvant radiotherapy (RT) and to analyze prognostic factors of survival in the International Federation of Gynecology and Obstetrics (FIGO) IB-IIA uterine cervical cancer. Materials and Methods: We retrospectively reviewed the medical records of 148 patients with FIGO IB-IIA uterine cervical cancer who underwent surgery followed by adjuvant RT at the Yonsei Cancer Center between June 1997 and December 2011. Adjuvant radiotherapy was delivered to the whole pelvis or an extended field with or without brachytherapy. Among all patients, 57 (38.5%) received adjuvant chemotherapy either concurrently or sequentially. To analyze prognostic factors, we assessed clinicopathologic variables and metabolic parameters measured on preoperative 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). To evaluate the predictive performance of metabolic parameters, receiver operating characteristic curve analysis was used. Overall survival (OS) and disease-free survival (DFS) were analyzed by the Kaplan-Meier method. Results: The median follow-up period was 63.2 months (range, 2.7 to 206.8 months). Locoregional recurrence alone occurred in 6 patients, while distant metastasis was present in 16 patients, including 2 patients with simultaneous regional failure. The 5-year and 10-year OSs were 87.0% and 85.4%, respectively. The 5-year and 10-year DFSs were 83.8% and 82.5%, respectively. In multivariate analysis, pathologic type and tumor size were shown to be significant prognostic factors associated with both DFS and OS. In subset analysis of 40 patients who underwent preoperative PET/CT, total lesion glycolysis was shown to be the most significant prognostic factor among the clinicopathologic variables and metabolic parameters for DFS. Conclusion: Our results demonstrated that adjuvant RT following hysterectomy effectively improves local control. From the subset analysis of preoperative PET/CT, we can consider that metabolic parameters may hold prognostic significance in early uterine cervical cancer patients. More effective systemic treatments might be needed to reduce distant metastasis in these patients.