• Journal of Information Technology Applications and Management
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• 제29권6호
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• pp.63-80
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• 2022

In this paper, we study structural changes and performance gains in condition-based maintenance process redesign when mobile IoT technology is embedded into urban railway rolling stock. We first develop condition-based maintenance To-Be process model in accordance with the IoT deployment scheme. Secondly, we draw upon theoretical framework of redesign process analysis to develop performance evaluation method suitable to predictive maintenance shift from As-Is ordinary maintenance practice. Subsequently, To-Be process performance evaluations are conducted adopting both the quantitative and qualitative method for time, cost, and dependability dimensions. The results ascertain the considerable benefits captured through detection abnormality prior to actual rolling stock failure occurrence, and details of performance improvements and enhancement of standardization level is revealed. The procedures and results presented in this paper offers useful insights in the fields of IoT economic analysis, condition based maintenance, and business process redesign.

• 대한기계학회논문집A
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• 제31권1호
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• pp.26-35
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• 2007

The vehicle of urban transit is a complex system that consists of various electric, electronic, and mechanical equipments, and the maintenance cost of this complex and large-scale system generally occupies sixty percent of the LCC (Life Cycle Cost). For reasonable establishing of maintenance strategies, safety security and cost limitation must be considered at the same time. The concept of system reliability has been introduced and optimized as the key of reasonable maintenance strategies. For optimization, three preceding studies were accomplished; standardizing a maintenance classification, constructing RBD (Reliability Block Diagram) of VVVF (Variable Voltage Variable Frequency) urban transit, and developing a web based reliability evaluation system. Historical maintenance data in terms of reliability index can be derived from the web based reliability evaluation system. In this paper, we propose applying inverse problem analysis method and hybrid neuro-genetic algorithm to system reliability optimization for using historical maintenance data in database of web based system. Feed-forward multi-layer neural networks trained by back propagation are used to find out the relationship between several component reliability (input) and system reliability (output) of structural system. The inverse problem can be formulated by using neural network. One of the neural network training algorithms, the back propagation algorithm, can attain stable and quick convergence during training process. Genetic algorithm is used to find the minimum square error.

• Smart Structures and Systems
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• 제23권6호
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• pp.669-682
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• 2019

Vibration mitigation of cables or hangers is one of the crucial problems for cable supported bridges. Previous research focused on the behaviors of cable with dampers or crossties, which could help engineering community apply these mitigation devices more efficiently. However, less studies are available for hybrid applied cross-ties and dampers, especially lack of both analytical and experimental verifications. This paper studied damping and frequency of two parallel identical cables with a connection cross-tie and an attached damper. The characteristic equation of system was derived based on transfer matrix method. The complex characteristic equation was numerically solved to find the solutions. Effects of non-dimensional spring stiffness and location on the maximum cable damping, the corresponding optimum damper constant and the corresponding frequency of lower vibration mode were further addressed. System with twin small-scale cables with a cross-link and a viscous damper were tested. The damping and frequency from the test were very close to the analytical ones. The two branches of solutions: in-phase modes and the out-of-phase modes, were identified; and the two branches of solutions were different for damping and frequency behaviors.

• 한국농촌건축학회논문집
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• 제23권2호
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• pp.9-16
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• 2021

The purpose of this study is to maintain the existing characteristics of the city by utilizing the physical decline status and floating population in small and medium cities residential areas. In addition, it intends to present the direction of flexible urban regeneration and maintenance by reflecting regional characteristics and current status. A total of three data were used in this study. Building data, floating population data, and census output area data were used. Building data and floating population data were classified into five classes. The graded data were joined to the census output area data and analyzed by overlapping the two data. As a result of analysis of 17 residential areas in 5 small and medium cities in Jeollanam-do, 4 types, 2 management models, and 4 indicators could be presented by grade and regional characteristics. This study is meaningful in that it is possible to plan regionally customized urban regeneration/maintenance management plans and projects through the typology of the current status and characteristics of the region, which is an important step in the bottom-up form.

• 한국습지학회지
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• 제15권3호
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• pp.317-328
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• 2013

울산시의 대표적인 5개 도시하천인 무거천, 약사천 여천천, 명정천 및 척과천 등 5개 하천을 대상으로 유지용수 공급방법과 그에 따른 생태복원 정도를 조사하여 비교 검토하였다. 유지용수의 지속적인 공급으로 하천의 수질을 획기적으로 개선시킬 수 있었고 생태계가 점진적으로 복원되는 것을 확인할 수 있었다. 하지만 염도가 높거나 수질이 좋지 못한 유지 용수는 비록 많은 양을 공급하더라도 생태계 복원에 도움이 되지 못하거나 오히려 악영향을 미칠 수 있는 것으로 확인되었다. 하폭이 좁은 도시하천을 생태하천으로 조성하거나 유지하기 위해서는 산책로 조성 등 시설물 설치는 최소화해야 하고, 적절한 유지용수 확보와 본류 하천과의 연결성이 가장 중요한 것으로 판단되었다.

• 도시과학
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• 제6권2호
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• pp.17-27
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• 2017

최근, 하천의 수질오염 및 악취발생으로 민원이 증가하여 하천환경개선에 큰 관심이 모아지고 있다. 본 연구의 목적은 하수 유입부에 대해 무인항공기(UAV)를 활용하여 RGB 및 적외 열 영상을 획득하고 하천제방 정비 계획 및 하천 오염 현황의 모니터링을 위한 응용성을 검토하였다. 특히, 하천 인근 공장에서 배출되는 폐수를 적외 열 영상으로 검출하여 폐수의 전파를 모니터링하였다. 또한 하천 제방 정비대상 지역과 인근지역에 대한 RGB영상을 SfM(Structure from Motion)기반 영상 해석을 통해 고정밀 3차원 모형을 제작하고 정확성을 검토하였다. 연구결과, UAV영상을 활용, 폐수유입에 따른 하천의 온도변화를 감지하여 수질오염의 유입부 및 전파 현상을 모니터링 할 수 있었다. 또한 고정밀 3차원 모델(수치지형도, 정사영상)을 제작, 정확성을 검토하고 하천의 제방정비를 위한 정밀 3차원 정보 및 식생 피복정보를 도출할 수 있었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.22-26
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• 2011

The urban transit vehicles has very complicated structures composed electric and mechanical parts and systems. Its system is important to insure operating stability pursuant to massive transfer. Also, its system takes a lot of maintenance cost than constructing cost due to its system which has longtime life cycle. Generally it is know that maintenance cost affect a lot on total cost because its life cycle cost takes a part more than 60~70%. For these reason, it is really important to reduce its maintenance cost through efficiently operation and maintenance management system construction.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.265-271
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• 2007

To develop the most effect maintenance system of urban MAGLEV train which is being developed based on system engineering, logistics belong to special system engineering were applied to maintenance system and Integrated Logistic Supports (ILS) were employed to tailor every step of MAGLEV project. Since ILS had not been applied to domestic train project, the followings were studied to validate ILS: 1) case studies on maintenance procedures at home and abroad, 2) overview of standardized process of ILS, 3) Comparison and analysis of relationship between RAMS and ILS, 4) Application of ILS to MAGLEV maintenance system and other domestic train system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.259-264
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• 2003

Failure code system must include data of maintenance history, classification of failure, affective range and situation when failure occur. But the present failure code system have used a simple code system for classification to include only merchandise and tools. Advantageously, expansional standard code system that will be developed, it make that users can take steps of standardized overhaul and inspection as proposal maintain contents when failure occur or something wrong in vehicle of urban transit. Standardized failure codes must be developed and used that manufacturing companies and urban transit operating companies in order to give effect to maintenance works.

• 한국조경학회지
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• 제17권1호
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• pp.17-27
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• 1989

^x Good Planning, design, and maintenance will be the product of a Process which considers both the nature of man and the nature of nature. Recentry, we emphasize how social and psycological theory, behavioral studios, and community participation may contribute to practical decision making and to the development of appropriate form for human use at all scales of Landscape Architecture. The main purpose of this study was to develop more rational and user oriented theory of urban park planning, design, and maintenance in terms of social - behavioral approach. Study sites were Jungang, Dalsung, Duryu, and Apsan park, where were located Daegu city. In this study, user satisfaction determinants of each park, which were useful for park planning, design and maintenance, were discovered. Privacy and territoriality were examined as an important factors for design a park road examined as an important factors to design a Path and a comfortable space in urban park.