• 한국도로학회논문집
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• 제17권3호
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• pp.1-12
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• 2015

PURPOSES : This paper presents a description of the current issues facing road managers regarding the surface-type conversion of low-volume roads for cost savings. METHODS: The paper reviews previous works conducted toward this end, acknowledges gaps in the current research, and lays out what information is needed for further studies. RESULTS : If the cost to maintain an unsurfaced road is less than the cost of maintaining a surfaced road, then there is potential for cost savings for the management agency. However, the problem is bigger than simply maintaining the roads that already exist. If unsurfaced roads prove to be more economical than surfaced roads, then the cost to convert from a surfaced to an unsurfaced roadway, and vice versa, when necessary, must also be examined. CONCLUSIONS : No other studies have addressed the un-surfacing of a road for cost savings, and it is therefore unknown whether substantial savings can be realistically obtained by converting from a surfaced to an unsurfaced road. To determine whether a conversion policy would be a viable option, additional data and research are needed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1511-1516
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• 2011

The maintenance of the turnout is composed of signal field and track field on business, the electrical and mechanical field on system. adjustment and maintenance carry forward through coordination with these fields. In the case of turnout equipment used in a first phase of Seoul-Busan high-speed train, it is treated by classifying as mechanical adjustments and electrical adjustments. Mechanical adjustment is conducted with focus on fine adjustment to meet maintenance standards limits(1mm or less) about interval of basic rail and tongue rail about each part of track transition equipment. This refers to mechanical adjustments performed mainly with physical changes and movement characteristics between basic rail and tongue rail by considering the overall environment surrounding track side of section installed track transition equipment. However, these series of maintenance are conducted in state that high-speed train is not in the process from 1 am to 4 am at night, but common workers for maintenance are not familiar with the operation and checking about various situation, and the workers are even insufficient. Maintenance training using mixed reality is conducted in the place of business, we tried to overcome several problems of safety and time reduction through this training.

• Computers and Concrete
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• 제17권4호
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• pp.499-521
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• 2016

In this paper, a probabilistic- and finite element-based approach to evaluate and predict the lifetime performance of reinforced concrete (RC) bridges undergoing various maintenance actions is proposed with the time-variant system reliability being utilized as a performance indicator. Depending on their structural state during the degradation process, the classical maintenance actions for RC bridges are firstly categorized into four types: Preventive type I, Preventive type II, Strengthening and Replacement. Preventive type I is used to delay the onset of steel corrosion, Preventive type II can suppress the corrosion process of reinforcing steel, Strengthening is the application of various maintenance materials to improve the structural performance and Replacement is performed to restore the individual components or overall structure to their original conditions. The quantitative influence of these maintenance types on structural performance is investigated and the respective analysis modules are written and inputted into the computer program. Accordingly, the time-variant system reliability can be calculated by the use of Monte Carlo simulations and the updated the program. Finally, an existing RC continuous bridge located in Shanghai, China, is used as an illustrative example and the lifetime structural performance with and without each of the maintenance types are discussed. It is felt that the proposed approach can be applied to various RC bridges with different structural configurations, construction methods and environmental conditions.

• Asian-Australasian Journal of Animal Sciences
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• 제29권10호
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• pp.1398-1406
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• 2016

In general, the seminiferous tubule basement membrane (STBM), comprising laminin, collagen IV, perlecan, and entactin, plays an important role in self-renewal and spermatogenesis of spermatogonial stem cells (SSCs) in the testis. However, among the diverse extracellular matrix (ECM) proteins constituting the STBM, the mechanism by which each regulates SSC fate has yet to be revealed. Accordingly, we investigated the effects of various ECM proteins on the maintenance of the undifferentiated state of SSCs in pigs. First, an extracellular signaling-free culture system was optimized, and alkaline phosphatase (AP) activity and transcriptional regulation of SSC-specific genes were analyzed in porcine SSCs (pSSCs) cultured for 1, 3, and 5 days on non-, laminin- and collagen IV-coated Petri dishes in the optimized culture system. The microenvironment consisting of glial cell-derived neurotrophic factor (GDNF)-supplemented mouse embryonic stem cell culture medium (mESCCM) (GDNF-mESCCM) demonstrated the highest efficiency in the maintenance of AP activity. Moreover, under the established extracellular signaling-free microenvironment, effective maintenance of AP activity and SSC-specific gene expression was detected in pSSCs experiencing laminin-derived signaling. From these results, we believe that laminin can serve as an extracellular niche factor required for the in vitro maintenance of undifferentiated pSSCs in the establishment of the pSSC culture system.

• 조명전기설비학회논문지
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• 제12권4호
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• pp.114-121
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• 1998

본 논문에서는 건축물의 전기 수용설비에 대한 유지관리방법의 온라인화를 구현하기 위한 시스템을 제안하였다. 제안왼 시스템은 유지관리 방법에 대한 경험자 규칙을 활용한 데이터베이스를 구축하여 운전자가 응답파 대답을 통하여 유지관리에 업무가 수행되도록 하였다. 운전자는 본 시스템을 통하여 수용 설비의 정밀한 감시, 이상 상태의 조기발견, 올바른 조작 수행, 신속한 조치가 가능하며, 특히 비 전문가라도 설비의 유지관리업무가 가능하도록 개발되었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1174-1181
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• 2011

This paper investigates the current established preventive maintenance and its corresponding data on a point machine among railway signalling facilities and suggests a part of considerable plans when the policy of the preventive maintenance is modified. It is not appropriated to apply the optimized preventive replacement period considered with the cost simply. In that case, it is suggested that the reliability should be analyzed failure mode and effects through collecting the on-site failure data sufficiently. Then, that result can be proposed to adjust the proper criteria into the rational way by comparing the initial maintenance criteria. In this paper, the alternative way to determine the feasibility of the inspection period using failure probability is introduced.

• 한국건설관리학회논문집
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• 제15권1호
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• pp.51-61
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• 2014

건물의 사전 보수작업은 시설물이 제 기능을 발휘할 수 있도록 성능을 유지하고 향후에 발생할 수 있는 결함을 미연에 방지할 수 있다는 점에서 관심과 중요성이 증가하고 있다. 효과적인 사전 보수작업 수행을 위해 보수작업이 필요한 대상을 명확히 선정해야 하며 이를 위해 작업 대상이 가지는 상태에 대한 정확한 분석과 평가가 선행되어야 한다. 작업 대상의 성능 측정은 하나의 평가 기준에 대한 평가 보다는 여러 개의 평가 기준들을 동시에 고려한 평가가 측정의 정확성을 향상시킬 수 있다. 하지만 의사결정자의 주관적인 판단에 의해 측정값이 부정확한 평가 기준들이 존재할 수 있다. 이를 보완하고자 본 연구는 다양한 평가 기준을 이용한 사전 보수작업 대상의 성능 측정과 효과적인 작업 대상 선정을 위한 의사결정 지원 모델을 제시한다. 본 연구는 작업 대상 선정을 위한 평가 기준을 선정하고 기준별로 측정값을 종합하여 의사결정 과정에서 활용할 수 있도록 한다. 또한 건물의 상태 측정 시, 평가자의 주관적인 판단의 애매함으로 인해 발생하는 결과의 불확실성을 보완하고자 퍼지 집합을 사용하여 측정을 실시한다. 본 연구를 통해 의사결정자는 보수작업 대상 선정 과정에서 객관적인 평가를 위한 도구로 활용할 수 있다. 또한 본 모델은 의사결정자의 주관적인 의도에 따른 다양한 절충값을 얻을 수 있어, 의사결정자별 상이한 평가 방식을 반영할 수 있다.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.662-666
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• 2005

Using data gathered from expert opinion of plant and equipment professionals; this paper presents the key variables that may constitute a maintenance proficient plant operator. The Multivariate Discriminant Analysis (MDA) was applied to generate data and was tested for sensitivity analysis. Results showed that the MDA model was able to classify plant operators' proficiency at 94.10 percent accuracy and determined nine (9) key variables of a maintenance proficient plant operator. The key variables included: i) number of years of experience as equipment operator (PQ1); ii) eye-hand coordination (PQ9); iii) eye-hand-foot coordination (PQ10); iv) planning skills (TE16); v) pay/wage (MQ1); vi) work satisfaction (MQ4); vii) operator responsibilities as defined by management (MF1); viii) clear management policies (MF4); and ix) management pay scheme (MF5). The classification procedure of nine variables formed the general model with the equation viz: OMP (general) = 0.516PQ1 + 0.309PQ9 + 0.557PQ10 + 0.831TE16 + 0.8MQ1 + 0.0216MQ4 + 0.136MF1 + 0.28MF4 + 0.332MF5 - 4.387

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1436-1442
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• 2020

Nuclear infrastructure systems play an important role in national security. The functions and missions of nuclear infrastructure systems are vital to government, businesses, society and citizen's lives. It is crucial to design nuclear infrastructure for scalability, reliability and robustness. To do this, we can use machine learning, which is a state of the art technology used in various fields ranging from voice recognition, Internet of Things (IoT) device management and autonomous vehicles. In this paper, we propose to design and develop a machine learning algorithm to perform predictive maintenance of nuclear infrastructure. Support vector machine and logistic regression algorithms will be used to perform the prediction. These machine learning techniques have been used to explore and compare rare events that could occur in nuclear infrastructure. As per our literature review, support vector machines provide better performance metrics. In this paper, we have performed parameter optimization for both algorithms mentioned. Existing research has been done in conditions with a great volume of data, but this paper presents a novel approach to correlate nuclear infrastructure data samples where the density of probability is very low. This paper also identifies the respective motivations and distinguishes between benefits and drawbacks of the selected machine learning algorithms.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.149-154
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• 2008

국내 교량구조물의 대부분은 구조물, 자체에 의한 열화, 손상과 같은 물리적인 수명에 의하여 공용수명이 결정될 수 있어야 하지만, 이에 대한 연구가 미비하여 교량의 유지관리시 최적 유지관리 시나리오를 선정하는데 많은 어려움이 있다. 최적의 유지관리 시나리오를 선정하기 위해서는 부재별 열화에 의한 상태변화 및 유지관리를 위한 보수보강 효과를 고려한 상태/성능 분석이 반드시 요구되며, 본 연구에서 제안된 상태변화모델을 기반으로 기존에 구축된 DB 및 현재 운용중인 고속도로교량관리시스템(Highway Bridge Management System; HBMS)에 LCC 분석을 접목한 시스템개선의 효과 증대를 이를 수 있을 것으로 고려된다.