• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.274-283
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• 2002

This paper presents an efficient models for reinforeced concrete structures using CART-ANFIS(classification and regression tree-adaptive neuro fuzzy inference system). a fuzzy decision tree parttitions the input space of a data set into mutually exclusive regions, each of which is assigned a label, a value, or an action to characterize its data points. Fuzzy decision trees used for classification problems are often called fuzzy classification trees, and each terminal node contains a label that indicates the predicted class of a given feature vector. In the same vein, decision trees used for regression problems are often called fuzzy regression trees, and the terminal node labels may be constants or equations that specify the Predicted output value of a given input vector. Note that CART can select relevant inputs and do tree partitioning of the input space, while ANFIS refines the regression and makes it everywhere continuous and smooth. Thus it can be seen that CART and ANFIS are complementary and their combination constitutes a solid approach to fuzzy modeling.

• Childhood Kidney Diseases
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• 제20권1호
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• pp.1-5
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• 2016

Since many years, continuous low dose antibiotic prophylaxis (CAP) has been used for children at a risk for recurrent urinary tract infection (UTI), especially those with vesicoureteral reflux (VUR). The incidence of recurrent UTI has been shown to be higher in children with VUR with bladder and bowel dysfunction (BBD) than in those with VUR without BBD. Therefore, CAP has been recommended for children with BBD and VUR because of the increased risk of UTI. However, the use of CAP has become highly controversial because of bacterial resistance developed due to antibiotic over-usage. The preventive effects of probiotics have been proved in various adult urogenital infections, and the antimicrobial activities of lactobacilli against uropathogens have been demonstrated in previous in vitro studies. However, a critical assessment of their efficacy in children with UTI is lacking. The importance of the use of urogenital probiotics is that it is a natural approach that replenishes the depleted normal flora to create a better environment to fight off uropathogens. Probiotics have a great potential, particularly today with the increasing threat of antibiotic-resistant microorganisms.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.261-268
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• 2006

This study represents results of fragility curve development for 3-span continuous bridge. To research the response of bridge under earthquake excitation, Monte Carlo simulation is performed to study nonlinear dynamic analysis. Because of limited number of real time histories from the Korean peninsula, a set of 150 synthetic time histories were generated. Fragility corves in this study are represented by lognormal distribution functions with two parameters and developed as a function of PGA. Five damage states were defined to express the condition of damage based on the actual experimental damage data of bridge column. As a result of this research, the value of damage probability corresponding to each damage state were determined. This approach may be used in constructing the fragility curves for all of bridge structure and, by extension, in constructing the seismic hazard map.

• 대한의생명과학회지
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• 제23권3호
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• pp.185-193
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• 2017

Malnutrition is common and the major risk factor of mortality of end stage renal disease (ESRD) patients. The aim of this study is to assess nutritional status of malnutrition patients on dialysis by various methods and compare nutritional parameters of continuous ambulatory peritoneal dialysis (CAPD) patients with hemodialysis patients. 137 patients on dialysis from April 2009 to July 2013 were enrolled. Nutritional parameters of 66 CAPD and 71 hemodialysis patients were investigated by anthropometry, biochemical study, diet analysis and questionnaires. Malnutrition patients were selected by body mass index (BMI), serum albumin and pre-albumin based on International Society of Renal Nutrition and Metabolism (ISRNM) diagnostic criteria for protein-energy wasting and compared with non-malnutrition patients. In comparison of CAPD and hemodialysis patients, most anthropometric values showed no significant difference except total body water (TBW). TBW was lower in CAPD patients (P=0.024). Although serum albumin was slightly higher in hemodialysis patients (P=0.047), pre-albumin were significantly higher in CAPD patients (P=0.000). Serum blood urea nitrogen (BUN) was higher in hemodialysis patients (P=0.000). In diet analysis, Total calorie (P=0.000) and total cholesterol (P=0.012) intakes were higher in CAPD patients. Mean subjective global assessment (SGA) grade was higher in CAPD patients (P=0.003). Several nutritional parameters of CAPD patients were better than hemodialysis patients implying more intensive therapeutic approach may be needed for hemodialysis patients. We have to understand multiple factors contributing malnutrition of ESRD patients and individualized therapeutic approach is needed.

• Structural Engineering and Mechanics
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• 제85권4호
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• pp.531-543
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• 2023

The existing concrete bridges are time-varying working systems, where the maintenance strategy should be planned according to the time-varying performance of the bridge. This work proposes a time-dependent residual capacity assessment procedure, which considers the non-stationary bridge load effects under growing traffic and non-stationary structural deterioration owing to material degradations. Lifetime bridge load effects under traffic growth are predicated by the non-stationary peaks-over-threshold (POT) method using time-dependent generalized Pareto distribution (GPD) models. The non-stationary structural resistance owing to material degradation is modeled by incorporating the Gamma deterioration process and field inspection data. A three-span continuous box-girder bridge is illustrated as an example to demonstrate the application of the proposed procedure, and the time-varying reliability indexes of the bridge girder are calculated. The accuracy of the proposed non-stationary POT method is verified through numerical examples, where the shape parameter of the time-varying GPD model is constant but the threshold and scale parameters are polynomial functions increasing with time. The case study illustrates that the residual flexural capacities show a degradation trend from a slow decrease to an accelerated decrease under traffic growth and material degradation. The reliability index for the mid-span cross-section reduces from 4.91 to 4.55 after being in service for 100 years, and the value is from 4.96 to 4.75 for the mid-support cross-section. The studied bridge shows no safety risk under traffic growth and structural deterioration owing to its high design safety reserve. However, applying the proposed numerical approach to analyze the degradation of residual bearing capacity for bridge structures with low safety reserves is of great significance for management and maintenance.

• 항공우주정책ㆍ법학회지
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• 제28권1호
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• pp.73-96
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• 2013

ICAO는 기존의 항공안전평가제도를 개선한 항공안전평가제도(USOAP)를 1995년 도입하였다. 이는 최근의 항공기 사고율 감소에 효과적인 역할을 하고 있다고 평가되고 있으며 이러한 성과를 바탕으로 2013년부터는 기존의 '스냅샷 방식'에서 '상시 모니터링 방식(USOAP-Continuous Monitoring Approach)'으로 전환하였다. ICAO 항공안전평가 결과는 오늘날 국제사회에서 국가의 '항공안전 신인도'를 판단하는 객관적인 지표로써 항공산업에 막대한 영향을 미치고 있으며, 특히 평가결과가 미흡할 경우엔 항공노선 확충 및 코드쉐어 금지, 환승객 감소 국제항공 비즈니스 및 보험료 인상 등 경제적 불이익을 감수해야 한다. 또한, ICAO는 기존의 법규이행(Prescriptive Approach)을 기본으로 하되 리스크 기반(Risk-based) 사전예방형(Proactive Approach) 항공안전시스템 개념을 새로 도입하는 등 국제항공안전정책 패러다임을 전환하여 왔다. ICAO가 새로운 국제항공안전정책을 추진함에 따라 대한민국 정부도 이에 발맞춰 국내항공안전정책을 변화시켜 왔다. 특히, 시스템적 안전관리를 위해 기존의 법규이행 중심의 정부 안전감독시스템에 리스크 기반의 사전 예방적 안전관리 개념을 도입하고 있으며, ICAO 국제기준에 따라 항공서비스제공자에게 자체 안전관리시스템(SMS)를 운영토록 항공법에 규정하였다. 또한, 항공안전의 중심 분야인 항공기 운항 및 정비 분야에 대한 안전 증진을 위해 다양한 안전정책을 추진하고 있다. 이러한 신 국제항공안전정책 패러다임 변화에 발맞춰 국제사회에서 가장 모범적인 항공안전시스템을 갖춘 나라로 확고히 자리 매김하고, 우리 항공의 경쟁력을 튼튼하게 뒷받침한다는 계획이다. 이를 위해서는 정부, 항공사, 연구기관 등 항공관계자가 모두가 노력할 때 실질적인 효과를 기대할 수 있을 것이다.

• 한국재난정보학회 논문집
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• 제8권3호
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• pp.310-318
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• 2012

본 연구의 목적은 국내 안전보건경영시스템의 올바른 정착과 지속적인 개선을 통한 산업재해를 줄이기 위한 시스템 성숙도평가를 제안하는데 있다. KOSHA 18001시스템 실행의 현재 수준파악과 성숙도 측정의 검증을 통한 결과로서 다음 내용으로 요약된다. 시스템의 지속적인 성숙도 등급 향상을 위해서는 경영층 인식부문(의사결정) 46.0%, 본사지원활동 32.0%, 현장실행참여 22.0%로 중요도 로 검증되었다. 본사/현장의 활동은 위험성평가, 안전보건 재해예방활동, 성과평가 및 모니터링, 자원관리 및 지원, 경영검토 및 개선 등 활동의 중요도 순으로 실행 우선순위가 결정되었다. 또한, 전문가 그룹은 시스템의 강점, 약점, 개선주제를 제시함으로써 지속적인 개선활동과 연계시켜야 시스템을 정착할 수 있다고 제시하였다. 셋째, 안전보건경영시스템 실행의 성숙도 등급을 관리할 수 있는 도구를 제시하였다.

• Structural Monitoring and Maintenance
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• 제5권3호
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• pp.363-377
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• 2018

The proper functioning of critical points on transport infrastructure is decisive for the entire network. Tunnels and bridges certainly belong to the critical points of the surface transport network, both road and rail. Risk management should be a holistic and dynamic process throughout the entire life cycle. However, the level of risk is usually determined only during the design stage mainly due to the fact that it is a time-consuming and costly process. This paper presents a simplified quantitative risk analysis method that can be used any time during the decades of a tunnel's lifetime and can estimate the changing risks on a continuous basis and thus uncover hidden safety threats. The presented method is a decision support system for tunnel managers designed to preserve or even increase tunnel safety. The CAPITA method is a deterministic scenario-oriented risk analysis approach for assessment of mortality risks in road tunnels in case of the most dangerous situation - a fire. It is implemented through an advanced risk analysis CAPITA SW. Both, the method as well as the resulting software were developed by the authors' team. Unlike existing analyzes requiring specialized microsimulation tools for traffic flow, smoke propagation and evacuation modeling, the CAPITA contains comprehensive database with the results of thousands of simulations performed in advance for various combinations of variables. This approach significantly simplifies the overall complexity and thus enhances the usability of the resulting risk analysis. Additionally, it provides the decision makers with holistic view by providing not only on the expected risk but also on the risk's sensitivity to different variables. This allows the tunnel manager or another decision maker to estimate the primary change of risk whenever traffic conditions in the tunnel change and to see the dependencies to particular input variables.

• Geomechanics and Engineering
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• 제5권5호
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• pp.379-399
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• 2013

In practice, analysis of laterally loaded piles is carried out using beams on non-linear Winkler springs model (often known as p-y method) due to its simplicity, low computational cost and the ability to model layered soils. In this approach, soil-pile interaction along the depth is characterized by a set of discrete non-linear springs represented by p-y curves where p is the pressure on the soil that causes a relative deformation of y. p-y curves are usually constructed based on semi-empirical correlations. In order to construct API/DNV proposed p-y curve for clay, one needs two values from the monotonic stress-strain test results i.e., undrained strength ($s_u$) and the strain at 50% yield stress (${\varepsilon}_{50}$). This approach may ignore various features for a particular soil which may lead to un-conservative or over-conservative design as not all the data points in the stress-strain relation are used. However, with the increasing ability to simulate soil-structure interaction problems using highly developed computers, the trend has shifted towards a more theoretically sound basis. In this paper, principles of Mobilized Strength Design (MSD) concept is used to construct a continuous p-y curves from experimentally obtained stress-strain relationship of the soil. In the method, the stress-strain graph is scaled by two coefficient $N_C$ (for stress) and $M_C$ (for strain) to obtain the p-y curves. $M_C$ and $N_C$ are derived based on Semi-Analytical Finite Element approach exploiting the axial symmetry where a pile is modelled as a series of embedded discs. An example is considered to show the application of the methodology.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2016년도 학술발표회
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• pp.189-189
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• 2016

To generate information that contributes to climate change risk management, it is important to perform a precise assessment on the impact in diverse aspects. Considering this academic necessity, Japanese government launched continuous research project for the climate change impact assessment, and one of the representative project is Program for Risk Information on Climate Change (Sousei Program), Theme D; Precise Impact Assessment on Climate Change (FY2012 ~ FY2016). In this research program, quantitative impact assessments have been doing from a variety of perspectives including natural hazards, water resources, and ecosystems and biodiversity. Especially for the natural hazards aspect, a comprehensive impact assessment has been carried out with the worst-case scenario of typhoons, which cause the most serious weather-related damage in Japan, concerning the frequency and scale of the typhoons as well as accompanying disasters by heavy rainfall, strong winds, high tides, high waves, and landslides. In this presentation, a framework of comprehensive impact assessment with the worst-case scenario under the climate change condition is introduced based on a case study of Theme D in Sousei program There are approx. 25 typhoons annually and around 10 of those approach or make landfall in Japan. The number of typhoons may not change increase in the future, but it is known that a small alteration in the path of a typhoon can have an extremely large impact on the amount of rain and wind Japan receives, and as a result, cause immense damage. Specifically, it is important to assess the impact of a complex disaster including precipitation, strong winds, river overflows, and high tide inundation, simulating how different the damage of Isewan Typhoon (T5915) in 1959 would have been if the typhoon had taken a different path, or how powerful or how much damage it would cause if Isewan Typhoon occurs again in the future when the sea surface water temperature has risen due to climate changes (Pseudo global warming experiment). The research group also predict and assess how the frequency of "100-years return period" disasters and worst-case damage will change in the coming century. As a final goal in this research activity, the natural disaster impact assessment will extend not only Japan but also major rivers in Southeast Asia, with a special focus on floods and inundations.