• 한국자동차공학회논문집
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• 제17권5호
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• pp.97-106
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• 2009

An objective of this study is to give practical information that could be used for calculating pollutant emission factors and fuel economy from Korean Inspection & Maintenance program, which has been using steady state acceleration simulation mode. Concentration results from I/M test is adequately converted to mass emission factors and fuel efficiency data, which have unit of g/km and km/L, respectively. Exhaust volume flow(EVF), which is for converting emission result from concentration to mass, is measured by tracer method in various vehicle speed - power condition. It is found that there is an apparent second order relationship between EVF and vehicle inertia weight. EVF is expressed in function of vehicle inertia weight in order to estimate EVF in I/M site without measuring device. Converted mass emission results from measured EVF and raw emission analyzer show a satisfactory agreement with those from conventional CVS-bag type measurement system. Mass emission factors and fuel efficiency from measured EVF and estimated EVF also show good agreement to each other. Considering that an I/M program has great advantages to recruit-based emission test in terms of the number of test vehicle, the information in this study can be used for developing an alternative procedure to collect more various data to establish national database of mobile emission factors and fuel economy, even though the driving cycle in I/M program is steady state cycle rather than transient cycle.

• 한국구조물진단유지관리공학회 논문집
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• 제12권2호
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• pp.139-148
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• 2008

기 시행된 관련 보고서에 의하면 외관 상태에 대한 육안 점검은 구조적 안전성 평가를 위해 대단히 중요한 부분이다. 본 연구는 개별 손상유형의 분리 평가에 의한 콘크리트 바닥판에 대하여 개선된 상태평가 방법을 제안한다. 먼저, 한데 묶여서 다루어졌던 여러 유형의 손상들을 분리하고, 다음으로 현행 지침을 토대로 가중점수를 부여하였다. 그 밖의 전반적인 과정은 혼란을 피하기 위하여 가능한 한 그대로 유지하였다. 제안된 방법을 4개의 교량에 대해 기 수행된 진단프로젝트에 적용, 시험 결과는 본 방법이 실무에서 드러난 현행 지침의 논점을 보완할 수 있다는 점에서 합리성과 적용성을 보여준다. 상세 분할 및 가중평가에 근거한 합리적인 시스템 평가와 함께 과도 손상 부재의 특별 관리로 이원화함으로써 보수 보강에 대한 적정성과 경제성을 부여하고 안전성을 확보할 수 있다. 본 연구의 이원화된 평가방법은 가치공학의 적용 영역을 유지관리 단계로 확장한다.

• 대한공간정보학회지
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• 제13권1호
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• pp.89-96
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• 2005

최근 도로 및 지하시설물 관련 GIS시스템 구축이 각 지방자치단체들에서 하나, 둘씩 완료되어감에 따라 해당 지방자치단체들의 관심은 기존의 GIS시스템 구축으로부터 이제 1차 완료된 GIS시스템의 유지관리로 서서히 변화되고 있다. 이와 같은 현상은 시간이 지날수록 더욱 증대할 것이며 따라서 해당 지방자치단체들은 기 구축된 GIS시스템을 유지관리하기 위한 여러 관점에서의 지침 및 지원이 필요한 시점이다. GIS시스템의 유지관리란 주제는 그 영역이 상당히 광범위하고 그 시기적인 필요성 또한 일부 앞서 GIS시스템을 구축한 지방자치단체들로부터 크게 공감되고 있는 것으로 조사되었다. 그럼에도 불구하고 현재까지 GIS시스템의 유지관리와 관련되어 체계적으로 수행된 연구는 양적으로나 질적으로 매우 미비한 상황으로 파악되었으며 이에 본 연구는 GIS시스템 유지관리란 주제를 체계적으로 접근하기 위한 시도의 일환으로 그중 가장 근본적인 요소라고 판단되는 GIS데이터 유지관리의 차원에서 우선 접근하고자 시도되었다. 이를 위해 조사된 지방자치단체들의 GIS시스템 유지관리 관련 현황이 체계적으로 정리되었고 이를 분석하여 GIS데이터 관련 문제점 유형 및 지방자치단체의 해결발안을 도출하였다. GIS데이터는 기본도와 지하 시설물도로 나누어 각각 접근 및 분석되어 지방자치단체를 위한 효율적인 GIS데이터 유지관리방안을 제시하였다.

• 가정과삶의질연구
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• 제17권4호
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• pp.31-46
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• 1999

This study aims to investigate the difference of the financial state, the expenditure patterns of household, the expenses of Auto, and the influential variables on the purchase in automobiles according to the auto-installment. The important findings from the data based on the samples of household with only one car on the Korea Household Pannel Study by Daewoo Institute. 1) The financial state of installment households were not good than those of non-installment. 2) The expenditures of the purchase and maintenance of installment household were higher than those of non-installment. 3) Variables affecting to the expenses of the purchases of installment households were the evacuation of car, in the case of new car, household's net assets and the living level compared to last year. In those of non-installment households were the evacuation of car and in the case of new car.

• Journal of Power Electronics
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• 제18권5호
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• pp.1585-1594
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• 2018

The estimation of $LiFePO_4$/graphite battery states suffers from the prominent hysteresis phenomenon between the respective open-circuit voltage curves towards charging and discharging. A lot of hysteresis models have been documented to investigate the hysteresis mechanism. This paper reviews and deeply interprets four non-electrochemical hysteresis models and some improvements. These models can be conveniently incorporated into commonly used equivalent circuit models to reproduce battery behaviors. Through simulation and experimental comparisons of voltage predictions and state-of-charge estimations, the pros and cons of these models are presented.

• Structural Monitoring and Maintenance
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• 제1권4호
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• pp.427-449
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• 2014

A hybrid optimization method for the identification of state-space models is presented in this study. Hybridization is succeeded by combining the advantages of deterministic and stochastic algorithms in a superior scheme that promises faster convergence rate and reliability in the search for the global optimum. The proposed hybrid algorithm is developed by replacing the original stochastic mutation operator of Evolution Strategies (ES) by the Levenberg-Marquardt (LM) quasi-Newton algorithm. This substitution results in a scheme where the entire population cloud is involved in the search for the global optimum, while single individuals are involved in the local search, undertaken by the LM method. The novel hybrid identification framework is assessed through the Monte Carlo analysis of a simulated system and an experimental case study on a shear frame structure. Comparisons to subspace identification, as well as to conventional, self-adaptive ES provide significant indication of superior performance.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.895-904
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• 2015

This paper presents a probabilistic approach of reliability evaluation and economic assessment for solving transmission network expansion planning problems. Three methods are proposed for TNEP, which are reorganizing the existing power system focused on the buses of interest, selecting candidates using modified system operating state method with healthy, marginal and at-risk states, and finally choosing the optimal alternative using cost-optimization method. TNEP candidates can be selected based on the state reliability such as sufficient and insufficient indices, as proposed in this paper. The process of economic assessment involves the costs of construction, maintenance and operation, congestion, and outage. The case studies are carried out with modified IEEE-24 bus system and Jeju island power system expansion plan in Korea, to verify the proposed methodology.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2004년도 추계학술대회
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• pp.115-123
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• 2004

Replacement problems can be classed as either deterministic of stochastic. Deterministic problems are those in which the timing and the outcome of the replacement action are assumed to be known with certainty. Before proceeding with development of replacement models it is important to note that preventive replacement actions, that is, ones taken before equipment reaches a failed state, require two necessary conditions: (1) The total cost of the replacement must be greater after failure than before. (2) The failure rate of the equipment must be increasing. Equipment is subject to failure. On failure, one of two possible actions can be taken : repair or complete replacement of the failed equipment. In this paper, we proposed optimal overhaul, repair, replacement maintenance model with two-state.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.164-169
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• 2003

This paper is presented to a theory comparing each different systems by quantitatively analyzing reliability. availability, maintenance and safety. Reliability R(t) produced by the method here is used for MTBF calculation of system as reliability of normal state. It is possible to produce the failure rate of unsafety state through modelization of system only to use the failure rate, after yielding the failure rate of failure mode to each unsafety sate in case that unsafety state is defined with the function of systems applied.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1365-1370
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• 2004

In this paper, a novel anti-sway control system that uses an inclinometer as a sway sensor is investigated. The inclinometer, when compared with a vision system, is very cheap, durable, and its maintenance is easy. However, it gives almost the same performance. Various observers for estimating the angular velocity of the load and the trolley velocity are presented. A state feedback controller with an integrator is designed. After a time-scale analysis, a 1/4-size pilot crane of the rail-mounted quayside crane is constructed. The performance of the proposed control system was verified with a real rubber-tired gantry crane at a container terminal as well as with the pilot crane constructed. Experimental results are provided.