• International Journal of Concrete Structures and Materials
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• 제11권1호
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• pp.115-133
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• 2017

To investigate the effectiveness of using fiber reinforced polymer (FRP) sheets in confining heat-damaged columns, 15 circular RC column specimens were tested under axial compression. The effects of heating duration, stiffness and thickness of the FRP wrapping sheets were examined. Two specimen groups, six each, were subjected to elevated temperatures of $500^{\circ}C$ for 2 and 3 h, respectively. Eight of the heat-damaged specimens were wrapped with unidirectional carbon and glass FRP sheets. Test results confirmed that elevated temperatures adversely affect the axial load resistance and stiffness of the columns while increasing their ductility and toughness. Full wrapping with FRP sheets increased the axial load capacity and toughness of the damaged columns. A single layer of the carbon sheets managed to restore the original axial resistance of the columns heated for 2 h yet, two layers were needed to restore the axial resistance of columns heated for 3 h. Glass FRP sheets were found to be less effective; using two layers of glass sheets managed to restore the axial load carrying capacity of columns heated for 2 h only. Confining the heat-damaged columns with FRP circumferential wraps failed in recovering the original axial stiffness of the columns. Test results confirmed that FRP-confining models adopted by international design guidelines should address the increased confinement efficiency in heat-damaged circular RC columns.

• 대한기계학회논문집A
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• 제31권4호
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• pp.525-531
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• 2007

The operating temperature has been increased to improve the efficiency of gas turbine. The most advanced Gas turbine is operated at above $1,500^{\circ}C$. Improvement in material and cooling method permit hot gas path component to run at increased temperature. But, the repair of blades which are developed with advanced manufacture technique is difficult to use normal welding. Most of gas turbine blades are made of precipitation harden nickel base superalloy, which is very hard to weld. Therefore, the employment of welding filler on blade is solid solution nickel base superalloy(Hastelloy X, Inconel 617). In this study, Tensile test in high temperature was conducted on welded GTD111DS with GTD111 to evaluate effect of variation of pre, post treatment. The result of this study showed that the specimen was treated with optimum pre and post treatment(preweld HT($1200^{\circ}C$), Post treatment($1100^{\circ}C$ HIP, $1200^{\circ}C$ + $1100^{\circ}C$ + $800^{\circ}C$ HT) is mush superior.

• 산업경영시스템학회지
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• 제22권53호
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• pp.45-54
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• 1999

Manufacturing today is becoming increasingly competitive. If a company is to exist and successfully compete, it must pay very careful attention to production management, total quality assurance and total proactive maintenance issues. Overall machine performance, repair efficiency, system level utilization, productivity and quality of output need to be optimized as possible. To accomplish that objective, the behavior of manufacturing equipment and systems need to be monitored and measured continuously if it is possible. Then early warning of possible failure should be generated and proacted on that type of the situation to improve overall operation performance of manufacturing environment. In this paper, Proactive maintenance framework using performance-based reliability structure as enabler technology is proposed. Its paradigm enables one to maximize system through-put and product quality as well as resources in the performance domain. In the case of inadequate knowledge of the failure mechanics, this empirical modeling concept along with performance degradation knowledge can serve as an important product and process improvement tool. The real-time framework extension to proposed framework uses on-line performance information and is capable of projecting the remaining useful period.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2004년도 추계학술대회
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• pp.131-141
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• 2004

This study deals with the procedure of safety improvement, productivity increase, and tact-time reduction through setting up the system about preventive maintenance. Actually, it is hard to establish and carry out preventive maintenance, even though we recognize the importance of the system concerning time, cost, labor, and so forth. In this study in the viewpoint of cost we are for achieving maximum efficiency by change and reduction of planning process adapted to the special work group. At first we briefly will mention the kind, the necessity, and the concept of preventive maintenance, and then divide the equipment used in the assembly line into the two whether it is necessary or not by way of estimating the breakdown loss, comparing with general establishment of preventive maintenance and modifying it to the case. At the second step we will establish the operation system of plan management related to production and quality in the special case. Check period and category will be set by dividing the assembly equipment into LCL and Focus in the third step. The forth step will contain the operation procedure in detail. And then we must make check and repair record periodically. Finally, on the basis of the record the selection of checking of significance will be conducted. This results in safety improvement, tact time reduction, and productivity improvement.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.224-226
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• 2017

본 논문은 복합화력 발전용 가스터빈 고온부품을 관리하기 위해 개발된 S/W의 구성 및 기능에 대하여 소개한다. 고온부품의 경우 수리 및 재생, 교체 빈도가 높아 효율적인 관리를 통해 운용 경제성을 크게 높일 수 있다. 또한 개발된 프로그램은 윈도우형 인터페이스를 제공하여 사용자가 보다 쉽게 사용할 수 있으며 프로그램의 확장을 통해 전체 계통 부품으로 확대 적용이 가능하다.

• 한국국방경영분석학회지
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• 제28권1호
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• pp.115-135
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• 2002

The limits of current DN(Defense networks), private and closed network, become to reality; for Example, high expense of construction and maintenance of networks, restriction of new subscribers on DN. Therefore, a network using web environment that reflect fast development of If and IS(Information Security) technology is demanded for MND. Meeting the requirement of reliable IS system and extension and improvement of DN using common network, we can reduce the expense to extend, maintain, repair DN, form the environment that makes military business cooperate better with civil company and government agency, advance implementing Defense computing and networking service for field small size units that was a exception of Defense digitalization. But it is essential to construct DN based on common network that there are security requisites; confidentiality, integrity, availability, efficiency, log, backup, restoration, that have to be realized at demanding level for IS. This thesis suggested four measurements; replacement DN with common network to resolve the requirements of building new network and improvement of performance for private DN, linkage with common network for new requirement, distribution of traffic using common network, configuration of DN using Internet and Proposed a refinement of IS management organization to treat security threat of common network flexibly, and LAN IS standard model of DN based on the web environment.

• 한국가스학회지
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• 제11권3호
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• pp.56-63
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• 2007

오늘날 고객의 요구는 보다 더 다양해지고 있고, 시장 환경이 급속히 변화함에 따라 기업의 모든 활동은 고객중심으로 이루어지고 있다. 최근 제품 및 서비스의 품질 향상을 위해 변화혁신 활동을 추진한 기업이 늘어나고 있는 실정이다. 본 연구는 도시가스 공급시설을 효율적으로 보수하기 위하여 6시그마 기법을 이용하여 공급시설 건전성에 영향을 주는 핵심인자를 도출하였으며, Risk 인자는 정량적인 평가를 통하여 시그마 값을 산출하였고, 근본원인 및 해결안을 도출, 새로운 프로세스를 적용하여 통계적 공정관리를 실행하였다. 도시가스 공급시설의 안전관리는 위험을 정량화하여 통계적인 공정관리를 통하여 산포를 줄이고, 품질관리 비용을 제거해서 효율적인 경영관리가 가능하며, 6시그마 이용 기법의 정착과 효율적인 운용의 확산을 통해 과학적인 안전관리가 가능할 것으로 기대된다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 Asia Navigation Conference
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• pp.129-133
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• 2006

In China, the traditional method of artificial and periodical cruise is still adopted for the AtoN management, which has brought many disadvantages to the work of the AtoN management, such as non real-time, fallibility, and low efficiency However, with the rapid development of AIS technique, now AIS equipments have been widely installed on ships, and on the other hand China Maritime Safety Administration (abr. China MSA) is carrying out the scheme of AIS base station network in china, based on which the digital AtoN will develop in the future. According to what have been analyzed above, this paper puts forward a design of AtoN wireless surveillance system based on AIS. The system consists of AIS on AtoN, AIS base station and AtoN management center. It can provide such functions as the information gathering, managing of AtoN and the service of navigation assistance. This paper gives the whole design including the work theory, the hardware structure and the software scheme of the system, and finally gives the simulation software of the AtoN management center. The AtoN wireless surveillance system brought forward by this paper will be more efficient with less repair cost and less work of the supervisors. It will bring revolutionary progress in the navigation aids system in China.

• Industrial Engineering and Management Systems
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• 제9권2호
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• pp.70-79
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• 2010

Makespan and cost minimization are two important factors in project investment. This paper considers a multi-mode resource-constrained project scheduling problem with the objective of minimizing costs, subject to a deadline constraint. A number of studies have focused on minimizing makespan or resource availability cost with a specified deadline. This problem assumes a fixed cost for the availability of each renewable resource per period, and the project cost to be minimized is the sum of the variable cost associated with the execution mode of each activity. The presented memetic algorithm (MA) consists of three features: (1) a truncated branch and bound heuristic that serves as effective preprocessing in forming the initial population; (2) a strategy that maintains two populations, which respectively store deadline-feasible and infeasible solutions, enabling the MA to explore quality solutions in a broader resource-feasible space; (3) a repair-and-improvement local search scheme that refines each offspring and updates the two populations. The MA is tested via ProGen generated instances with problem sizes of 18, 20, and 30. The experimental results indicate that the MA performs exceptionally well in both effectiveness and efficiency using the optimal solutions or the current best solutions for the comparison standard.

• 한국안전학회지
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• 제26권5호
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• pp.7-12
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• 2011

The crash cushion has drawn a great attention because of its versatility, efficiency and simplicity in reducing the mortality and damages from traffic accidents. However, the existing cushion systems are high priced or have limited functions. The purpose of the study was to devise an improved crash cushion which can offer higher safety compared to the available ones at present. In addition, the conformity of the cushion with the facility standards was assessed through computer simulation for collision with vehicles. The novel cushion system adopts the used tires as shock absorber, which can not only secure cushioning effect but also reduce the production cost. Moreover, it is highly durable and easy to maintain and repair the damaged parts. According to the simulation using BARRIER VII program, the novel cushion system showed PHD of 17.4 g and 10.1 g for a frontal collision and a side collision, respectively. Based on the results, it could be concluded that the novel cushion system met the test standards in the guideline for road safety facility installation and management.