• 대한토목학회논문집
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• 제37권1호
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• pp.175-185
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• 2017

가스 사용의 지속적인 증대로 이에 따른 가스의 제조, 취급, 사용이 점점 확대되어 관련 시설이 대형화, 복잡화되어, 이로 인한 크고 작은 사고가 지속적으로 발생하고 있다. 이러한 사고는 인명피해 및 물적 손실 뿐만 아니라 국가의 경제적인 손실의 큰 원인이 된다. 가스시설의 공통적으로 많은 부분을 차지하고 있는 Pipe Line 부분에 외부의 영향에 의한 사고가 가장 큰 위험요소를 가지고 있다. 특히, 도심지역 및 인구밀집지역의 경우의 고압가스배관의 사고 발생은 경제적 손실을 비롯한 보다 많은 손실을 야기시킬 수 있다. 이러한 매설배관의 사고에 대한 예방대책으로 여러 관련 기관에서는 가스배관에 대한 안전성을 확보하기 위해서는 전체 시스템의 파손 및 위험요소를 효과적으로 평가할 필요가 있다. 특히 가스배관이 설치되거나 작동되어 질 때에 이러한 파손(failure)의 가능성을 매우 작게 하더라도 위험요소가 존재하게 된다. 그러나 일단 파손이 발생하면 인명 및 재산상의 피해가 매우 크기 때문에 파손의 원인을 분석하여 파손사고의 비율을 최소한으로 낮추는 것이 필요하다. 그러므로 본 논문에서는 Scoring Model의 정성적 위험성 분석기법을 이용하여 매설배관의 위험성을 점수로 표현하여 정량적인 숫자로 표현하였다. 이러한 가시적인 평가의 결과는 매설배관의 안전을 확보하여 실질적인 매설배관의 유지관리를 하는데 있어서 매우 효율적으로 적용될 수 있을 것이다.

• International Journal of Advanced Culture Technology
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• 제6권3호
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• pp.163-172
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• 2018

The power train of hydro-mechanical continuously variable transmission(HMCVT) for the middle class forklift makes use of an hydro-static unit, hydraulic multi-wet disc brake & clutches and complex helical & planetary gears. The complex helical & planetary gears are a very important part of the transmission because of strength problems. The helical & planetary gears belong to the very important part of the HMCVT's power train where strength problems are the main concerns including the gear bending stress, the gear compressive stress and scoring failures. The present study, calculates specifications of the complex helical & planetary gear train and analyzes the gear bending and compressive stresses of the gears. It is necessary to analyze gear bending and compressive stresses confidently for an optimal design of the complex helical & planetary gears in respect of cost and reliability. This paper not only analyzes actual gear bending and compressive stresses of complex helical & planetary gears using Lewes & Hertz equation, but also verifies the calculated specifications of the complex helical & planetary gears by evaluating the results with the data of allowable bending and compressive stress from the Stress - No. of cycles curves of gears. In addition, this paper explains actual gear scoring and evaluates the possibility of scoring failure of complex helical & planetary gear train of hydro-mechanical continuously variable transmission for the forklift.

• Journal of the Korean Data and Information Science Society
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• 제24권1호
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• pp.85-94
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• 2013

금융시장의 규모가 점점 더 커짐에 따라 고객정보 관리 미숙 또는 부실한 의사결정, 즉 신용 리스크 관리 실패로 인한 손실이 막대하게 증가하고 있다. 따라서 신용 리스크 관리가 점차 더 중요해지고, 이런 신용 리스크를 최소화하는 기본적인 도구인 신용 평점 모형이 절실히 요구된다. 신용평점 모형은 주로 이항형 목표변수만 이용하여 개발 연구되었다. 본 논문에서는 순서형 다항 자료 또는 경시적 이항 자료 같은 다른 형태의 목표 변수를 고려한 신용평점 모형구축 방법을 제시한다. 그 개발된 모형을 실제 자료와 랜덤화한 자료에 적용하여 Kolmogorov-Smirnov 통계량으로 비교 분석한다.

• Tribology and Lubricants
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• 제39권5호
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• pp.173-182
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• 2023

The composite planetary gear reducer, a power transmission component of armored vehicles, operates at a high torque and is used in severe environments such as mountain, gravel or unpaved roads. Therefore, they must be designed and manufactured to have high durability. To design such a planetary gear reducer, there are numerous specifications to validate, such as selecting the module and the number of teeth of each gear satisfied the requirements, and calculating gear specifications and durability strength. Because planetary gears constitute a combination of several gears, there are many restrictions and interferences in selecting the number of teeth and addendum modification coefficients, and designing the tooth shape. Developing an auto design program is necessary to design various planetary gears more conveniently and quickly. In this study, a planetary gear reducer design software, widely used in various machines and armored vehicles, was developed. This design software can automatically select the number of teeth and modules of the gears, calculate specifications and quickly evaluate its fatigue durability strength and scoring failure according to the planetary gear reducer design theory.

• 시스템엔지니어링학술지
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• 제18권1호
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• pp.46-57
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• 2022

In this paper, we proposed the DFMEA Implementation Method for safety design of Weapon System. First, we presented the process for DFMEA. And then, the case analysis of OOO missile was performed in accordance with the process presented. After defining the system requirements of OOO missile, failure definition scoring criteria was set. In order to clarify the definition of failure, the failure was classified into safety, reliability, maintainability and others. After performing the function analysis, the relationship matrix analysis was performed to identify the failure mode according to the function without omission. After clarifying the failure classification, mode of failure, cause of failure and effect were analyzed to calculate the severity, occurrence and detection values. After the action priority was judged, the recommended action according to the failure classification was identified for the determined action priority. The results of this study can be used as a relevant basis for the design reflection and resource re-allocation of stakeholders.

• 산업경영시스템학회지
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• 제25권6호
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• pp.23-35
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• 2002

The problem of system reliability is very important issue in the digitalized nuclear power plant, because the failure of its system brings about extravagant economic loss, environment destruction, and fatal damage of human. Therefore the purpose of this study has developed the reliability evaluation model through the scoring model by the quantitative and qualitative factors in order to justify the evaluation considering the advanced safety factors in the Advanced Pressurized water Reactor 1400MWe(APR 1400MWe) under uncertainty. Especially, the qualitative factors considering the human, information control, and quality factors for the systematic and rational justification have been closely analyzed. The proposed model can be simply applied in real fields in order to minimize the industrial accidents in the digitalized nuclear power plant.

• 한국신뢰성학회지:신뢰성응용연구
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• 제6권1호
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• pp.51-61
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• 2006

Failure analyses were conducted on a crank shaft and a chock liner by using X-ray diffraction, optical microscopy and SEM/EDS techniques. In the crank shaft, a crack developed where a maximum tensile stress coincided with band structure formed by hot forging. The maximum tensile stress was observed to originate from volume expansion during high frequency induction heat treatment and the band structure to develop between upper and lower dies during hot forging. In the chock liner, the wear mechanism varied with the chemical affinity and hardness of liner material relative to friction pair of housing liner. Brass of low chemical affinity and hardness compared to housing liner showed uniform adhesive wear. STS 304 and STS 420J2 of high chemical affinity showed galling and scoring respectively.

• Journal of Trauma and Injury
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• 제34권1호
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• pp.3-12
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• 2021

Purpose: To evaluate the severity of trauma, many scoring systems and predictive models have been presented. The quick Sequential Organ Failure Assessment (qSOFA) is a simple scoring system based on vital signs, and we expect it to be easier to apply to trauma patients than other trauma assessment tools. Methods: This study was a cross-sectional study of trauma patients who visited the emergency department of Jeju National University Hospital. We excluded patients under the age of 18 years and unknown outcomes. We calculated the qSOFA, the Modified Early Warning Score (mEWS), Revised Trauma Score (RTS), and Injury Severity Score (ISS) based on patients' initial vital signs and assessments performed in the emergency department (ED). The primary outcome was mortality within 14 days of trauma. We analyzed qSOFA scores using multivariate logistic regression analysis and compared the predictive accuracy of these scoring systems using the area under the receiver operating characteristic curve (AUROC). Results: In total, 27,764 patients were analyzed. In the multivariate logistic regression analysis of the qSOFA, the adjusted odds ratios with 95% confidence interval (CI) for mortality relative to a qSOFA score of 0 were 27.82 (13.63-56.79) for a qSOFA score of 1, 373.31 (183.47-759.57) for a qSOFA score of 2, and 494.07 (143.75-1698.15) for a qSOFA score of 3. In the receiver operating characteristic (ROC) curve analysis for the qSOFA, mEWS, ISS, and RTS in predicting the outcomes, for mortality, the AUROC for the qSOFA (AUROC [95% CI]; 0.912 [0.871-0.952]) was significantly greater than those for the ISS (0.700 [0.608-0.793]) and RTS (0.160 [0.108-0.211]). Conclusions: The qSOFA was useful for predicting the prognosis of trauma patients evaluated in the ED.

• 산업경영시스템학회지
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• 제23권54호
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• pp.167-177
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• 2000

The problem of system reliability is very important issue in the nuclear power plant, because the failure of its system brings about extravagant economic loss, environment destruction, and quality loss. This paper therefore proposes a normalized scoring model by the qualitative factors order to evaluate the robust reliability of nuclear power plants under uncertainty. Especially, the qualitative factors including risk, functional, human error, and quality function factors for the robust justification has been also introduced. Finally, the analytical reliability and safety assessment model developed in this paper can be used in the real nuclear power plant.

• 대한임상독성학회지
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• 제12권1호
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• pp.14-21
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• 2014

Purpose: The objective of this study was to develop a new scoring tool that is comprehensively applicable and predicts fatality within 24 h of intoxication. Methods: This was a cohort study conducted in two emergency medical centers from 2011 to 2012. We identified factors associated with severe/fatality. Through a discriminant analysis, we devised the aBIG (age, Base deficit, Infection, and Glasgow coma scale) score. To compare the ability of aBIG to predict intoxication severity with that of previous scoring systems such as APACHE II, MODS, SAPS IIe, and SOFA, we determined the receiver operating characteristic curves of each variable in predicting severe-to-fatal toxicity. Results: Compared with the mild/moderate toxicity group (n=211), the severe/fatal group (n=143) had higher incidences of metabolic acidosis, infection, serious mental change, QTc prolongation and hepato-renal failure. Age, base deficit, infection-WBC count, and Glasgow Coma Scale were independently associated with severe/fatal poisoning. These variables were combined into the poisoning "aBIG" score [$0.28{\times}$Age group+$0.38{\times}WBC$ count/$10^3+0.52{\times}$Base deficit+$0.64{\times}$(15-GCS)], which were each calculated to have an area under the curve of 0.904 (95% confidence interval: 0.868-0.933). The aBIG poisoning score had an equivalent level of severity predictability as APACHE II and a superior than MODS, SOFA, and SAPS IIe. Conclusion: We developed a simplified scoring system using the four variables of age, base deficit, infected leukocytosis, and GCS. The poisoning aBIG score was a simple method that could be performed rapidly on admission to evaluate severity of illness and predict fatal severity in patients with acute intoxications.