• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.132-132
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• 2000

The reliability of EIC systems in hot rolling mill is indispensable and very important in order to maintain stable production. Signals obtained from sensors and control system should be analyzed to monitor the condition of down coiler in hot rolling mill. We develope a monitoring system of down coiler which is composed of three parts (1) data acquisition and MMI (2) signal processing and analyzing, and (3) automatic data saving. Also it is designed to enable to inform users the abnormal conditions of down coiler. This developed system is expected to make it possible to reduce long downtime, secure high facility precision, and maintain high control levels.

• 대한기계학회논문집B
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• 제29권11호
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• pp.1220-1228
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• 2005

Fault detection and diagnostic (FDD) systems have the potential to reduce equipment downtime, service costs, and utility costs. In this study, model based algorithm and fuzzy algorithm were used to detect and diagnose various fault at System multi-air conditioner. various fault include the Refrigerant Low charging, Fouling of Indoor Heat Exchanger, Fouling of Outdoor Heat Exchanger A experimental verification was conducted in the 6HP System multi-air conditioner on an 8-floor building. Test results showed diagnosis result about 78 $\~$ 90$\%$ for given faults. This Study lays the foundation fur future work on develope the real-time fault detection and diagnosis system for the System multi-air conditioner.

• 한국통신학회논문지
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• 제42권1호
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• pp.88-97
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• 2017

With the increasing of the penetration rate of large-scale wind farms, a reliable, highly available and cost-effective communication network is needed. As the failure of a WF communication network will significantly impact the control and real-time monitoring of wind turbines, network reliability should be considered into the WF design process. This paper analyzes the network reliability of different WF configurations for the Southwest Offshore project that is located in Korea. The WF consists of 20 WTs with a total capacity of 60 MW. In this paper, the performance is compared according to a variety of indices such as network unavailability, mean downtime and network cost. To increase the network reliability, partial protection and full protection were investigated as strategies that can overcome the impact of a single point of failure. Furthermore, the reliability performances of different network architectures are analyzed, evaluated and compared.

• 대한안전경영과학회지
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• 제19권3호
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• pp.89-95
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• 2017

This paper presents another maintenance policy for a group of units under finite operating horizon. A group of identical units are subject to random failures. Group maintenances are performed to all units together at specified intervals, and the failed units during operation are remained idle until the next group maintenance set-up. Unlike the traditional assumption of infinite operating horizon, we adopt the assumption of the finite operating horizon which reflect the rapid industrial advance and short life cycle of modern times. The units are under operation until the end of the operating horizon. Further, the operation of units are extended to the first group maintenance time after the end of the horizon. The total cost under the proposed maintenance policy is derived. The optimal group maintenance interval and the expected number of group maintenances during the horizon are found. It is shown that the proposed policy is better than the classical group maintenance policy in terms of total cost over the operating horizon. Numerical examples are presented for illustrations.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 추계학술대회 논문집
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• pp.217-217
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• 1999

The main objective of this study is to simulate the design and operational policies of the assembly shop of an automotive plant for planning purposes and to find possible improvements. The simulation study was used to answer the following questions: How does the sequence affect the daily throughput\ulcorner What are the bottlenecks to the assembly lines in a given scenario\ulcorner A Simulation model was developed in accordance with the objective of this study. The model incorporates detailed workstation logic to accurately model downtime results through the use of a pull cord system. It is written with SIMAN. The discrete event feature of SIMAN does not adequately model the conveyor systems of the asembly shop. As a result, a few subroutines were added to the SIMAN modeling structures to mimic the operations of the assembly shop. Use of the model uncovered attractive improvement opportunities, such as a tremendous gain in annual volume if four additional spaces were added to a between-line buffer.

• 산업경영시스템학회지
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• 제33권2호
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• pp.170-175
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• 2010

Maintaining a complex repairable system can be achieved by repairing, replacing, or any other activities. This paper proposes a joint optimization policy that is composed with ordering and replacing under minimal repair for the complex system. For this purpose, we derive the expected cost due to the minimal repair, ordering, downtime, inventory costs, and salvage value of units that follow generally distribution. Some properties about the optimum ordering policy that are suggested for our purpose shows that the optimum ordering policy minimizing the expected cost is either one of the two typical policies : (1) the original unit is replaced as soon as the ordered spare is delivered, or (2) the delivered spare is used as inventory part until the original unit fails.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1998년도 정기학술강연회 발표논문 초록집 Annual Meeting of Korean Society of Coastal and Ocean Engineers
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• pp.117-123
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• 1998

Long-period wave oscillations in a harbor could create unacceptable vessel movements leading to the downtime of moored ships. It is practically very difficult to prevent long-period harbor oscillations, but extension of breakwaters at the harbor mouth could be a countermeasure in part. Narrowing a harbor mouth might give rise to increase in the energy loss due to flow separation near the mouth, which in turn makes resonant periods of the harbor become longer, especially for the first (or Helmholtz) resonant mode. (omitted)

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2564-2566
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• 2001

The reliability of EIC(Electricity, Instrumentation and Computer) systems in hot rolling mill is very important in order to maintain stable production. Signals obtained from sensors and control system should be analyzed to monitor the condition of down coiler in hot rolling mill. We develop a monitoring system of down coiler which is composed of three parts : (1) data acquisition and MMI, (2) signal processing and analyzing, and (3) automatic data saving. Also it is designed to enable to inform users the abnormal conditions of down coiler. This developed system is expected to make it possible to reduce long downtime, secure high facility precision, and maintain high control levels.

• 터널과지하공간
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• 제4권2호
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• pp.144-155
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• 1994

This research is designed to assess current achievement levels for mechanized excavation systems in Korea adn suggest the model predictive of TBM performance using statistical approaches. A test section in the TBM construction sites is selected to measure and analyze TBM performance. The field records including operating data, time allocation into downtime catagories, and machine design are analyzed on a shift basis. There are a total of 240 shifts, with most days operating two shifts per day. Examples of the probability density functions produced from the test section are presented and discussed. Relationships between TBM penetration rate and rock physical properties are investigated and the empirical equations for TBM performance prediction are also assessed with the field data.

• Earthquakes and Structures
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• 제16권4호
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• pp.375-389
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• 2019

During earthquakes, the performance of structures needs to be evaluated, which provides guidance for selecting suitable retrofitting schemes. The purpose of this paper is to accomplish seismic assessment of a simple steel residential building. Once the responses of the system are determined, the scope of the study extends to evaluate selected retrofitting strategies that are intended to rehabilitate the flaws of the structure under prescribed ground motions with high probability of occurrence at the site. After implementing the retrofits, seismic assessment of the upgraded structure is carried out to check if the remediation at various seismic performance levels is acquired or not. Outcomes obtained from retrofitted scenarios are compared to the results obtained from the initial un-retrofitted configuration of the structure. This paper presents the process for optimal selection of rehabilitation solutions considering the cost of implementation, downtime and disruption to property owners while improving the seismic performance level of the structure.