• 제목/요약/키워드: Failure area index

검색결과 75건 처리시간 0.026초

비정상 물공급 시나리오를 고려한 상수도관망 최적 밸브위치 결정 (Optimal valve installation of water distribution network considering abnormal water supply scenarios)

  • 이승엽;정동휘
    • 한국수자원학회논문집
    • /
    • 제52권10호
    • /
    • pp.719-728
    • /
    • 2019
  • 상수도 관망 밸브는 평상시 관로의 유향을 변경하는 역할을 하지만, 관로 파손, 수질 문제 등 사고 발생 시 해당 구역을 격리하는데에도 이용된다. 밸브조작에 의한 구역 단수는 주변 지역의 압력 및 물 공급 성능 저하를 유발한다. 최근 안정적인 상수도 관망 물 공급을 위협하는 사고가 다양하고 빈번하게 발생하고 있으며, 이에 따라 다양한 시나리오를 고려하여 밸브 위치 결정을 하는 것이 필요하다고 할 수 있다. 따라서 본 연구에서는 밸브의 개수, 구역격리 시 물 부족량, 수리학적 거리 인자(Hydraulic Geodesic Index, HGI)를 통합한 목적함수를 개발하고, 다양한 물 부족 시나리오에 기반한 밸브 최적 위치 결정 방법론을 제안한다. 제안한 방법론은 페스카라 관망에 적용되었으며, 시나리오별로 도출된 최적 밸브 설계안의 차이점을 분석하였다. 최적 밸브 위치 탐색 과정 중 수행된 관망 수리해석은 압력 기반(Pressure Driven Analysis, PDA)으로 수행하였다. 개발된 방법론으로 도출한 최적 밸브 설계안은 기존 설계안 대비 밸브 개수가 최대 19개나 적었고, 세그먼트 격리 시 물 공급 부족량 또한 상대적으로 작았다. 수원 수두가 낮은 시나리오를 고려할수록 더 많은 밸브가 설치되었는데, 밸브 추가 설치에 따른 비용증가는 다양한 시나리오에서 물 공급 성능 향상으로 이어짐을 확인하였다. 또한, 세그먼트 격리 상황 모의를 압력 및 유량 기반 해석으로 수행한 결과를 비교하여, 밸브 최적 위치 설계 수행 시 압력 기반 해석이 필요함을 확인하였다.

Anti-Müllerian hormone as a predictor of polycystic ovary syndrome treated with clomiphene citrate

  • Hestiantoro, Andon;Negoro, Yuwono Sri;Afrita, Yohana;Wiweko, Budi;Sumapradja, Kanadi;Natadisastra, Muharam
    • Clinical and Experimental Reproductive Medicine
    • /
    • 제43권4호
    • /
    • pp.207-214
    • /
    • 2016
  • Objective: This study aimed to determine the threshold of $anti-M{\ddot{u}}llerian$ hormone (AMH) as predictor of follicular growth failure in polycystic ovary syndrome (PCOS) patients treated with clomiphene citrate (CC). Methods: Fifty female subjects with PCOS were recruited and divided into two groups based on successful and unsuccessful follicular growth. Related variables such as age, infertility duration, cigarette smoking, use of Moslem hijab, sunlight exposure, fiber intake, body mass index, waist circumference, AMH level, 25-hydroxy vitamin D level, and growth of dominant follicles were obtained, assessed, and statistically analyzed. Results: The AMH levels of patients with successful follicular growth were significantly lower (p= 0.001) than those with unsuccessful follicular growth ($6.10{\pm}3.52$ vs. $10.43{\pm}4.78ng/mL$). A higher volume of fiber intake was also observed in the successful follicular growth group compared to unsuccessful follicular growth group (p= 0.001). Our study found the probability of successful follicle growth was a function of AMH level and the amount of fiber intake, expressed as Y =-2.35+($-0.312{\times}AMH\;level$)+($0.464{\times}fiber\;intake$) (area under the curve, 0.88; 95% confidence interval, 0.79-0.98; p< 0.001). Conclusion: The optimal threshold of AMH level in predicting the failure of follicle growth in patients with PCOS treated with CC was 8.58 ng/mL.

지형공간 정보를 활용한 산사태 안정평가의 확률론적 해석 (Probabilistic Analysis for Stability Evaluation of Landslides Using Geo-spatial Information)

  • 박병수
    • 대한공간정보학회지
    • /
    • 제14권3호
    • /
    • pp.55-62
    • /
    • 2006
  • 본 연구는 산사태의 발생 가능성을 평가하기 위하여 지형공간 정보를 활용하여 지형자료를 구축하고, 힘의 평형으로 유도된 무한사면 안정해석모델을 적용하여 산사태 가능성을 정량적인 안전지표로 평가하였다. 또한, 해석모델에 입력인자의 불확실성을 고려할 수 있는 확률변수 개념을 도입하여 신뢰성 이론에 근거를 둔 산사태의 확률론적 분석법을 연구하였다. 이러한 해석방법의 적용성을 검토하기 위하여 실제 현장자료로부터 지형정보와 토질 조건 등을 획득하고, 넓은 지역에 대한 개략적 평가를 위한 전체해석과 세밀한 결과 도출을 위한 상세해석을 실시하였다. 이를 통하여 전반적인 산사태 발생 가능성 경향, 산사태 가능성이 높은 상세해석 구간 선정 및 상세구간에서의 보다 높은 정도의 산사태발생 가능성을 안전율과 파괴확률의 안정지표로 분석할 수 있었다.

  • PDF

태양광 모듈, 인버터 고장, 누설 및 아크 발생에 따른 태양광발전시스템의 발전량 최적화를 위한 상태진단 알고리즘 (Status Diagnosis Algorithm for Optimizing Power Generation of PV Power Generation System due to PV Module and Inverter Failure, Leakage and Arc Occurrence)

  • 윤용호
    • 한국인터넷방송통신학회논문지
    • /
    • 제24권4호
    • /
    • pp.135-140
    • /
    • 2024
  • 태양광발전시스템은 다른 재생에너지원과 비교해서 내구수명이 길어 유지점검이 거의 필요 없다고 하지만, 실제 태양광 모듈의 음영 발생, 온도상승, 미스매치, 오염·열화, 태양광 인버터의 고장, 누설전류 및 아크 발생으로 인하여 초기 설계 시에 기대했던 성능이 나오지 않는 경우가 발생한다. 따라서 이러한 시스템의 문제점 해결을 위해 단지 발전량 및 운전 현황에 대한 조사를 통하여 정성적으로 파악하거나 태양광발전시스템의 성능지수인 성능계수(PR, Performance Ratio)로부터 성능을 비교분석하고 있다. 그러나 큰 손실을 포함하고 있으므로 단지 성능계수만으로 태양광발전시스템의 성능 저하, 고장 혹은 결한 등의 이상 유무를 정확하게 판단하기가 어렵다. 본 논문에서는 주변 환경의 변화에 따른 태양광발전시스템 발전량 최적화를 위해 태양광 모듈의 음영 발생, 인버터 고장, 누설 및 아크에 대한 상태 진단 알고리즘을 연구하였다. 또한 연구된 알고리즘을 이용하여 영역별 상태진단과 이에 따른 발전량 최적화 운전에 대한 실증시험을 통한 결과를 고찰하였다.

Charlson comorbidity index as a predictor of periodontal disease in elderly participants

  • Lee, Jae-Hong;Choi, Jung-Kyu;Jeong, Seong-Nyum;Choi, Seong-Ho
    • Journal of Periodontal and Implant Science
    • /
    • 제48권2호
    • /
    • pp.92-102
    • /
    • 2018
  • Purpose: This study investigated the validity of the Charlson comorbidity index (CCI) as a predictor of periodontal disease (PD) over a 12-year period. Methods: Nationwide representative samples of 149,785 adults aged ${\geq}60$ years with PD (International Classification of Disease, 10th revision [ICD-10], K052-K056) were derived from the National Health Insurance Service-Elderly Cohort during 2002-2013. The degree of comorbidity was measured using the CCI (grade 0-6), including 17 diseases weighted on the basis of their association with mortality, and data were analyzed using multivariate Cox proportional-hazards regression in order to investigate the associations of comorbid diseases (CDs) with PD. Results: The multivariate Cox regression analysis with adjustment for sociodemographic factors (sex, age, household income, insurance status, residence area, and health status) and CDs (acute myocardial infarction, congestive heart failure, peripheral vascular disease, cerebral vascular accident, dementia, pulmonary disease, connective tissue disorders, peptic ulcer, liver disease, diabetes, diabetes complications, paraplegia, renal disease, cancer, metastatic cancer, severe liver disease, and human immunodeficiency virus [HIV]) showed that the CCI in elderly comorbid participants was significantly and positively correlated with the presence of PD (grade 1: hazard ratio [HR], 1.11; P<0.001; grade ${\geq}2$: HR, 1.12, P<0.001). Conclusions: We demonstrated that a higher CCI was a significant predictor of greater risk for PD in the South Korean elderly population.

유통업체의 부실예측모형 개선에 관한 연구 (Performance Evaluation and Forecasting Model for Retail Institutions)

  • 김정욱
    • 유통과학연구
    • /
    • 제12권11호
    • /
    • pp.77-83
    • /
    • 2014
  • Purpose - The National Agricultural Cooperative Federation of Korea and National Fisheries Cooperative Federation of Korea have prosecuted both financial and retail businesses. As cooperatives are public institutions and receive government support, their sound management is required by the Financial Supervisory Service in Korea. This is mainly managed by CAEL, which is changed by CAMEL. However, NFFC's business section, managing the finance and retail businesses, is unified and evaluated; the CAEL model has an insufficient classification to evaluate the retail industry. First, there is discrimination power as regards CAEL. Although the retail business sector union can receive a higher rating on a CAEL model, defaults have often been reported. Therefore, a default prediction model is needed to support a CAEL model. As we have the default prediction model using a subdivision of indexes and statistical methods, it can be useful to have a prevention function through the estimation of the retail sector's default probability. Second, separating the difference between the finance and retail business sectors is necessary. Their businesses have different characteristics. Based on various management indexes that have been systematically managed by the National Fisheries Cooperative Federation of Korea, our model predicts retail default, and is better than the CAEL model in its failure prediction because it has various discriminative financial ratios reflecting the retail industry situation. Research design, data, and methodology - The model to predict retail default was presented using logistic analysis. To develop the predictive model, we use the retail financial statements of the NFCF. We consider 93 unions each year from 2006 to 2012 to select confident management indexes. We also adapted the statistical power analysis that is a t-test, logit analysis, AR (accuracy ratio), and AUROC (Area Under Receiver Operating Characteristic) analysis. Finally, through the multivariate logistic model, we show that it is excellent in its discrimination power and higher in its hit ratio for default prediction. We also evaluate its usefulness. Results - The statistical power analysis using the AR (AUROC) method on the short term model shows that the logistic model has excellent discrimination power, with 84.6%. Further, it is higher in its hit ratio for failure (prediction) of total model, at 94%, indicating that it is temporally stable and useful for evaluating the management status of retail institutions. Conclusions - This model is useful for evaluating the management status of retail union institutions. First, subdividing CAEL evaluation is required. The existing CAEL evaluation is underdeveloped, and discrimination power falls. Second, efforts to develop a varied and rational management index are continuously required. An index reflecting retail industry characteristics needs to be developed. However, extending this study will need the following. First, it will require a complementary default model reflecting size differences. Second, in the case of small and medium retail, it will need non-financial information. Therefore, it will be a hybrid default model reflecting financial and non-financial information.

Early Aortic Valve Replacement in Symptomatic Normal-Flow, Low-Gradient Severe Aortic Stenosis: A Propensity Score-Matched Retrospective Cohort Study

  • Kyu Kim;Iksung Cho;Kyu-Yong Ko;Seung-Hyun Lee;Sak Lee;Geu-Ru Hong;Jong-Won Ha;Chi Young Shim
    • Korean Circulation Journal
    • /
    • 제53권11호
    • /
    • pp.744-755
    • /
    • 2023
  • Background and Objectives: Aortic valve replacement (AVR) is considered a class I indication for symptomatic severe aortic stenosis (AS). However, there is little evidence regarding the potential benefits of early AVR in symptomatic patients diagnosed with normal-flow, low-gradient (NFLG) severe AS. Methods: Two-hundred eighty-one patients diagnosed with symptomatic NFLG severe AS (stroke volume index ≥35 mL/m2, mean transaortic pressure gradient <40 mmHg, peak transaortic velocity <4 m/s, and aortic valve area <1.0 cm2) between January 2010 and December 2020 were included in this retrospective study. After performing 1:1 propensity score matching, 121 patients aged 75.1±9.8 years (including 63 women) who underwent early AVR within 3 months after index echocardiography, were compared with 121 patients who received conservative care. The primary outcome was a composite of all-cause death and heart failure (HF) hospitalization. Results: During a median follow-up of 21.9 months, 48 primary outcomes (18 in the early AVR group and 30 in the conservative care group) occurred. The early AVR group demonstrated a significantly lower incidence of primary outcomes (hazard ratio [HR], 0.52; 95% confidence interval [CI], 0.29-0.93; p=0.028); specifically, there was no significant difference in all-cause death (HR, 0.51; 95% CI, 0.23-1.16; p=0.110), although the early AVR group showed a significantly lower incidence of hospitalization for HF (HR, 0.43; 95% CI, 0.19-0.95, p=0.037). Subgroup analyses supported the main findings. Conclusions: An early AVR strategy may be beneficial in reducing the risk of a composite outcome of death or hospitalization for HF in symptomatic patients with NFLG severe AS. Future randomized studies are required to validate and confirm our findings.

Analysis of prognostic factors affecting poor outcomes in 41 cases of Fournier gangrene

  • Hahn, Hyung Min;Jeong, Kwang Sik;Park, Dong Ha;Park, Myong Chul;Lee, Il Jae
    • Annals of Surgical Treatment and Research
    • /
    • 제95권6호
    • /
    • pp.324-332
    • /
    • 2018
  • Purpose: We present our experience involving the management of this disease, identifying prognostic factors affecting treatment outcomes. Methods: The patients treated for Fournier gangrene at our institution were retrospectively reviewed. Data collected included demographics, extent of soft tissue necrosis, predisposing factors, etiological factors, laboratory values, and treatment outcomes. The severity index and score were calculated. Multivariate regression analysis was used to determine the association between potential predictors and clinical outcomes. Results: A total of 41 patients (male:female = 33:8) were studied. The mean age was 54.4 years (range, 24-79 years). The most common predisposing factor was diabetes mellitus (n = 19, 46.3%). Sixteen patients (39.0%) were current smokers. Seven patients had chronic kidney disease. The most frequent etiology was urogenital lesion (41.5%). The mortality rate was 22.0% (n = 9). Multivariate regression analyses showed that extension of necrosis beyond perineal/inguinal area and pre-existing chronic kidney disease were significant and independent predictors of mortality. Extension of necrosis beyond perineal/inguinal area was a significant predictor of increased duration in the intensive care unit and hospital stay. In addition, pre-existing chronic kidney disease was a significant predictor of flap reconstruction in the wound. Conclusion: Fournier gangrene with extensive soft tissue necrosis and pre-existing chronic kidney disease was associated with poor prognosis and complexity of patient management. Early recognition of dissemination and premorbid renal function is essential to reduce mortality and establish a management plan for this disease.

단양 지질공원 내의 산사태 유형과 특징 (Types and Characteristics of Landslides in Danyang Geopark)

  • 문성우;김호근;서용석
    • 지질공학
    • /
    • 제33권3호
    • /
    • pp.427-438
    • /
    • 2023
  • 본 연구에서는 다양한 암종이 분포하는 단양 지질공원 내에서 발생한 산사태를 대상으로 야외지질조사를 통해 유형을 분류하고, 샘플링 및 실내 시험을 통해 산사태 구성 물질의 역학적‧수리학적 특성을 분석하였다. 토석류 산사태 유형은 석회암 및 대리암, 셰일, 반상변정질 편마암 지역에서 발생하였으며, 석회암 및 대리암 지역에서는 카렌지형의 영향을 받아 암반과 암반 사이의 토사가 붕괴되는 형태로 다른 두 지역의 산사태와 구분된다. 토질시험 결과에서는 조립질 함량이 많은 편마암 풍화토가 다른 두 지역의 풍화토에 비해 내부마찰각이 높고 점착력이 작으며 투수계수가 큰 특징을 보인다. 암반 산사태 유형은 천매암, 사암, 역암 지역에서 발생하였으며, 천매암 지역에서는 평면파괴 형태가, 사암 지역에서는 부석형 낙석 형태가, 역암 지역에서는 전석형 낙석 형태가 발달하고 있다. 천매암의 전단강도는 동일한 암질의 타 암종에 비해 훨씬 낮게 나타나며, 역암의 슬레이크 내구성 지수는 타 암종과 유사하나 시험 전‧후 시료의 상태를 비교하면 기질부의 차별풍화 및 이로 인한 역의 탈락 형태가 뚜렷이 관찰된다. 본 연구의 결과는 지질특성별 산사태 유형에 따른 적절한 보강방안 및 방재대책을 수립하는데 기여할 수 있을 것으로 기대된다.

하인두암의 임상적 고찰 (Clinical Analysis on Cancer of the Hypopharynx)

  • 김영호;최은창;홍원표;김문석;이세영;홍정표;정형진
    • 대한두경부종양학회지
    • /
    • 제14권1호
    • /
    • pp.46-53
    • /
    • 1998
  • Background: Hypopharyngeal cancer represents about one-third the incidence of laryngeal cancer which is the most common cancer in head and neck area. Although there have been numerous reports regarding its clinical and statistical characteristics, more precise and ample data should be collected and analyzed in this country. Objectives: This study was designed to evaluate the pattern and patient's profile of the hypopharyngeal cancer, and we reviewed the treatment outcomes to search for an index of treatment modalities. Materials and Methods: The authors retrospectively analyzed 73 cases of hypopharyngeal cancer treated at Yonsei Medical Center during the 10-year period from 1985 to 1994. Five-year survival rate was calculated according to the primary site, clinical stage and treatment modality. Results: The incidence was predominated in male by 9 to 1 and peak incidence was 6th and 7th decades. Pyriform sinus was the main primary site(80.8%) followed by posterior hypopharyngeal wall(13.7%) and postcricoid area(5.5%). Advanced stage cancers(87.7%) were more common than early stage cancers. Radiotherapy(60.3%) was the most commonly used as primary treatment modality. Neck node metastasis was early occurred even in early stage cancers(61.5%), and overall rate of neck node metastasis was 69.9%. All surgical cases received procedures more than total laryngectomy and partial pharyngectomy. The most common cause of death was primary failure(81.5%) and it was highest in radiotherapy group. Five-year survival rate was significantly high in surgery group(90.9%). The overall 5-year survival rate of hypopharyngeal cancer was 30.3%. Conclusion: High index of suspicion should be required for early diagnosis. Also, surgery may be recommended for the primary treatment modality in advanced stage cancers.

  • PDF