• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1043-1048
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• 2011

In the case of a low density branch line, these areas are operating at a loss. So much money is used for infrastructure maintenance cost. To solve the problem, our institute have a project to develop the Information & Communication Technology based train operation system. In a similar research in the Europe, The UK's Transport Research Laboratory experienced analysis of operational issue for developing ERTMS from Level II to Level III. In this paper, we study about railway operational issues before development of ICT based train operation system. An analysis target of operational issues are railway business process & data, drivability and moving or virtual block system.

• Journal of Korean Society for Quality Management
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• v.33 no.4
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• pp.75-87
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• 2005

Generally speaking, weapon system is defined as a combination of primary system and support system which are evaluated by capability and operational availability respectively. Recently comparison of total life cycle cost shows that logistic support system is proved to be more important than primary system. However, until now systematic approach to support system development has not been applied in the area of developing support system. We need to construct a universal metric for effectiveness of logistic support system and to cut out whatever activities or support elements which do not contribute to the metric. This paper describes a new approach based on system engineering approach to logistic support system and also classifies five factors of failure, stock-out frequency, administrative delay time, active repair time and logistic delay time that have influence on operational availability of logistic support system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.113-122
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• 1998

In this paper we consider the CSP requirements determination problem of new equipment(machine) system. For the newly procured equipment systems, mathematical analyses are made for the system which is constructed with the consumable parts to derive the associated CSP requirement determination model in mathematical expression. Based on these analyses, a mathematical model is derived for making an optimal CSP requirement determination subject to tile constraint of satisfying any given operational availability limitation. We assume that the failure of a part follows a Poisson process. Firstly, the operational availability concept in CSP is defined and the relation between the general system availability and the operational availability is established. Secondly, the problem is formulated as the cost minimization problem that should satisfy the operational availability limitation, and then, using the generalized Lagrange multipliers method, the optimal solution procedure is derived.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.3
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• pp.110-116
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• 2008

Operational strategy for inventory control in the distribution system has been given attention. If an individual enterprise implements the strategy, it is not easy to gain scale merits because of limited quantity or burden of inventory. In this study, we propose an operational strategy for inventory control that considers managerial integration of regional distribution centers (RDCs) and present a model of it. In a network of several RDCs, they could share inventory information and supply parts for others in case of an inventory shortage. And a numerical example of the network is illustrated, which compares two operational strategies, integration management of RDCs and individual management of them. The result shows total cost reduction in the strategy of integration management through the efficient inventory control of multi-echelon distribution.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.59
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• pp.53-67
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• 2000

In this paper we consider the CSP requirements determination problem of new equipment(machine) system. For the newly procured equipment systems, mathematical analyses are made for the system which is constructed with the consumable parts and the repairable parts to derive the associated CSP requirement determination model in mathematical expression. Based on these analyses, a mathematical model Is derived for making an optimal CSP requirement determination subject to the constraint of satisfying any given operational availability limitation. We assume that the failure of a part follows a Poisson process and the repair time has an exponential distribution. Firstly, the operational availability concept in CSP is defined and the relation between the general system availability and the operational availability is established. Secondly, the problem is formulated as the cost minimization problem that should satisfy the operational availability limitation, and then, using the generalized Lagrange multipliers method, the optimal solution procedure Is derived.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.821-826
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• 2009

Current construction simulation approaches mostly focus on operation aspects of construction projects, ignoring managerial aspects which can radically change operational profiles (e.g., number of resources, expected productivity level, or daily working hours) during the course of construction. As a result, these approaches may mislead construction managers into unrealistic execution plans as well as make them difficult to find potential performance improvement areas. As an effort to address this issue, this paper establishes a comprehensive construction modeling framework which integrates operational and managerial aspects of construction projects. The proposed modeling framework will provide construction managers with more accurate, more reliable, and more realistic simulation results thus reducing the likelihoods of schedule delays and cost overruns.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.4
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• pp.100-108
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• 2013

In aerospace industry, MTBF (Mean Time Between Failure) and MFTBF (Mean Flight Time Between Failure) are generally used for reliability analysis. So far, especially to Korean military aircraft, MFTBF of avionic equipments is predicted by MIL-HDBK-217 and MIL-HDBK-338, however, the predicted MFTBF by military standard has a wide discrepancy to that of real-world operation, which leads to overstock and increase operation cost. This study analyzes operational data of avionic equipments. Operational MFTBF, which is calculated from operational data, is compared with predicted MFTBF calculated conventionally by military standard. In addition, failure rate trend is investigated to verify reliability growth in operational data, the investigation shows that failure rate curve from operational data has somewhat pattern with decreased failure rate and constant failure rate.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.307-310
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• 2016

The operational cost for maintaining the superconductivity of high-temperature superconducting (HTS) cables needs to be reduced for feasible operation. It depends on factors such as AC loss and heat transfer from the outside. Effective operation requires design optimization and suitable operational conditions. Generally, it is known that critical currents increase and AC losses decrease as the operational temperature of liquid nitrogen ($LN_2$) is lowered. However, the cryo-cooler consumes more power to lower the temperature. To determine the effective operational temperature of the HTS cable while considering the critical current and AC loss, critical currents of the HTS cable conductor were measured under various temperature conditions using sub-cooled $LN_2$ by Stirling cryo-cooler. Next, AC losses were measured under the same conditions and their variations were analyzed. We used the results to select suitable operating conditions while considering the cryo-cooler's power consumption. We then recommended the effective operating temperature for the HTS cable system installed in an actual power grid in KEPCO's 154/22.9 kV transformer substation.

• International Journal of Highway Engineering
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• v.15 no.3
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• pp.85-92
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• 2013

PURPOSES: The purpose of this paper is to estimate expected effects on traffic operational and economic aspects of 2+1 roads application in Korea. METHODS : Micro simulation study using VISSIM 5.0 was used to analyze the operation efficiency of 2+1 roads compared to two-lane highways and four-lane highways. Some scenarios for various traffic volumes were set up in order to analyze the effect of 2+1 roads under various traffic situations. Also imaginary road networks were set up for each type of roads. The MOEs to measure the operation efficiency were selected with average travel speed and delay. For analyzing economic effect of 2+1 roads, construction cost of a specific imaginary 2+1 road was compared to construction cost of a four-lane highway with same conditions. RESULTS: The results of study show that a 2+1 road is more effective with 19 percents higher average travel speed and 39 percents lower average delay than a two-lane highway. In the economic analysis, construction costs to construct a 2+1 road are saved as approximately 26.4~40.7 percents when compared to construction of four-lane highway. CONCLUSIONS: It can be concluded that 2+1 roads can improve the traffic operational level of service for two-lane highways and 2+1 roads can be applied as an effective design alternative for higher-volume two-lane highways in Korea.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.2
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• pp.166-172
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• 1999

Weapon system is defined as a combination of primary system and logistics support system which are evaluated by capability and operational availability respectively. Weapon system developer thought that primary system was weapon system and also only primary system was important. Recent comparison of total life cycle cost showed that logistics support system was proved to be more important than primary system. However, until now no systematic approach to logistics support system development have applied in the area of developing support system and much money was exhausted by wrong logistics support system. We need to construct a universal metric for effectiveness of logistics support system and to cut out whatever activities or support elements which do not contribute to the metrics. This study describes a new approach under the name function approach to logistics support system development and also classifies five factors of failure frequency, stock out of frequency, administrative delay time, active repair time and logistic delay time that have influence on operational availability of logistics support system.