• Industrial Engineering and Management Systems
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• 제9권3호
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• pp.251-261
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• 2010

This article demonstrated the application of the Fuzzy Data Envelopment Analytical Hierarchy Process (FDEAHP) to evaluate the root causes of critical defect problems occurring in the production of liquid medicine. The methodology of the research began by collecting the defect data by using Check Sheets, and ranking the significant problems by using a Pareto Diagram. Two types of major problems were found to occur, including glass fragments in the medicine and damaged lid threads. The causes of each problem were then analyzed by using Cause and Effect Diagrams. The significant causes were ranked by FDEAHP under three criteria, Severity (S), Occurrence (O) and Detection (D), followed by the framework of the FMEA Technique. Two causes with the highest Final Weight (FW) of each problem were selected to be improved, such as installing auxiliary equipment, using the Poka-Yoke system, setting the scale of the shaft and lathing the bushes of each bottle size. The results demonstrated a reduction in defects from 3.209% to 1.669% and showed that improving a few significant root causes, identified by an experienced decision maker, was sufficient to reduce the defect rate.

• 대한산업공학회지
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• 제21권4호
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• pp.609-628
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• 1995

This paper presents a reliability model and a data-analytic procedure for a repairable unit subject to failures due to multiple non-identifiable causes. We regard a failure cause as a state and assume the life distribution for each cause to be exponential. Then we represent the dependency among the causes by a Markov switching model(MSM) and estimate the transition probabilities and failure rates by maximum likelihood(ML) method. The failure data are incomplete due to masked causes of failures. We propose a specific version of EM(expectation and maximization) algorithm for finding maximum likelihood estimator(MLE) under this situation. We also develop statistical procedures for determining the number of significant states and for testing independency between state transitions. Our model requires only the successive failure times of a unit to perform the statistical analysis. It works well even when the causes of failures are fully masked, which overcomes the major deficiency of competing risk models. It does not require the assumption of stationarity or independency which is essential in mixture models. The stationary probabilities of states can be easily calculated from the transition probabilities estimated in our model, so it covers mixture models in general. The results of simulations show the consistency of estimation and accuracy gradually increasing according to the difference of failure rates and the frequency of transitions among the states.

• Neonatal Medicine
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• 제25권1호
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• pp.16-22
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• 2018

Purpose: This study investigated predictive factors for severe neonatal thrombocytopenia, which greatly increases the need for intensive care and is associated with a high mortality rate in premature infants. Factors adopted for prompt identification of at-risk newborns include blood test results and birth history. This study analyzed the relationship between the presence of severe neonatal thrombocytopenia and the mortality rate. The causes of thrombocytopenia in premature infants were also examined. Methods: This retrospective study evaluated 625 premature infants admitted to the neonatal intensive care unit (NICU) at Chung-Ang University Medical Center. The neonates were classified into 3 groups according to the severity of thrombocytopenia: mild ($100{\times}10^9/L{\leq}platelet<150{\times}10^9/L$), moderate ($50{\times}10^9/L{\leq}platelet<100{\times}10^9/L$), or severe (platelet<$50{\times}10^9/L$). Analysis of blood samples obtained at the onset of thrombocytopenia included platelet count, white blood cell (WBC) count, hemoglobin level, hematocrit level, absolute neutrophil count, and high-sensitivity C-reactive protein level. Results: Of the 625 premature infants admitted to our NICU, 214 were detected with thrombocytopenia. The mortality rate in thrombocytopenic neonates was 18.2% (39/214), whereas a mortality rate of only 1.0% was observed in non-thrombocytopenic neonates. The major causes of thrombocytopenia were perinatal insufficiency and sepsis in premature infants. Severe thrombocytopenia was noted more frequently in premature infants with higher WBC counts and in those with a younger gestational age. Conclusion: Platelet count, WBC count, and gestational age are reliable predictors for severe neonatal thrombocytopenia. The major causes of thrombocytopenia were perinatal insufficiency and sepsis in premature infants.

• International Journal of Advanced Culture Technology
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• 제8권1호
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• pp.71-81
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• 2020

This study is intended to determine the effects of volunteering participation motivation on major satisfaction and continuance willingness in ophthalmic optics students. To achieve this, a survey was empirically carried out to ophthalmic optics students. The research findings showed that self-development among participation motivation factors had a significant effect on major satisfaction and continuance willingness, leisure on continuance willingness, and major satisfaction on continuance willingness in the relationship between the effects of volunteering participation motivation on continuance willingness and major satisfaction in ophthalmic optics students, respectively, adopting 3 hypotheses. On the other hand, leisure had no significant effect on major satisfaction, interpersonal exchange on major satisfaction, and interpersonal exchange on continuance willingness, respectively, rejecting 3 hypotheses. Which suggest that the high self-development willingness of college students as a factor of college volunteering participation motivation causes them to have pride and specialization in their major. Consequently, pride and specialization in major cannot only increase an understanding of personality and major, but maintain a positive attitude, leading to a long-continuous willingness, not a simple one-time service.

• 한국자동차공학회논문집
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• 제20권6호
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• pp.9-16
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• 2012

It is often thought that when a fire is found in parked motor vehicles, the fire may occur after an engine stops. Also, it is easy to judge that when motor vehicle fires occur during engine stopping, it may be caused by arson or electrical causes irrespective of a fuel system. This study analyzed motor vehicle fires which occurred in operation but were found after parking and revealed that these fires were caused by the defect of a fuel system and the same motor vehicle types had fires by the same causes. Moreover, this study provided judgement process of major fire causes and periods for fire investigators to apply when investigating fires of parked motor vehicles. And this fire is related to automotive products liability.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1993년도 봄 학술회 논문집
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• pp.41-48
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• 1993

The 2nd phase of Seoul Subway, Lines 5,6,7 and 8, is in progress. To reduce the surface traffic congestion during construction the greater part of the system has been engineered by bored tunnelling. The current tunnelling methodology is based on the New Austrian Tunnelling Method. Serveral collapses have been reported to date. Most of the collapses took place in the area forwed with soft ground. The modes and causes of the collapses were progressive failures in the unsupported surface and sliding failures due to the unfavourable joint direction. The major causes turned out to be the weakness of ground and the sudden influx of ground water from the surface. Some measures to prevent the failures are also presented. To ensure the safe tunnelling ghrough the soft ground the unsupported excavation area has to be minimized and closed as early as possible. Additional support measures such as supporting core, sealing shotcrete, forepoling, spread footing, face rock bolting and grouting should be employed as well depend on ground conditions.

• 한국안전학회지
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• 제28권4호
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• pp.91-96
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• 2013

Forklift truck is one of the dangerous machines which causes the fatal accidents most frequently. The causes of fatalities by forklift from 2008 to 2011 were analyzed. Crushing the operator when tipping over or falling off a truck were the major causes of death in this study. The purpose of this study is to show measures from the engineering point of view to prevent the forklift truck accidents. In order for that, the domestic requirement for forklift safety was compared with those of foreign and international standards. The manufacturers' opinion was also collected regarding to improve the forklift safety. Several measures were suggested in order to prevent fatalities caused by forklift.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2006년도 정기학술발표대회 논문집
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• pp.268-270
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• 2006

The purpose of this paper was to explore delay avoiding measures and strategies. The paper was based on previous work of authors on finding delay causes. Firstly, the paper has discussed about delay avoidance measures prescribed by the previous work. As the previous study identified five main causes of construction delays, various measures and strategies to overcome those delay problems have been discussed in sequence in the last sections. Major delay prevention strategies are: involving stakeholders in the project decisions, outreach program, realistic time and resource estimation, try to adjust the triple constraints of time, cost and scope, ensure fair and complete disclosure of information at an early stage of the construction project, contractor, itself should inquire about patent design errors prior to submitting its bid, owner should include in its contract with the consultant an indemnity (protection) clause etc.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2013년 춘계학술대회
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• pp.41-52
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• 2013

Forklift truck is one of the dangerous machines which causes the fatal accidents most frequently. The causes of fatalities by forklift from 2008 to 2011 were analyzed. Crushing the operator when tipping over or falling off a truck were the major causes of death in this study. The purpose of this study is to show measures from the engineering point of view to prevent the forklift truck accidents. In order for that, the domestic requirement for forklift safety was compared with those of foreign and international standards. The manufacturers' opinion was also collected regarding to improve the forklift safety. Several measures were suggested in order to prevent fatalities caused by forklift.

• Clinical and Experimental Pediatrics
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• 제55권1호
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• pp.6-10
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• 2012

Human puberty is a complex, coordinated biological process with multiple levels of regulations. The timing of puberty varies greatly in children and is influenced by both environmental and genetic factors. The key genes of pubertal onset, $KISS1$, $GPR54$, $GNRH1$ and $GNRHR$, may be major causal factors underlying gonadotropin-releasing hormone-dependent precocious puberty (GDPP). Two gain-of-function mutations in $KISS1$ and $GPR54$ have been identified recently as genetic causes of GDPP. $GNRH1$ and $GNRHR$ are also gene candidates for GDPP; however no mutations have been identified in these genes. Presently potential genetic causes like $LIN28B$ continues to appear; many areas of research await exploration in this context. In this review, I focus primarily on the genetic causes of GDPP.