• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.643-645
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• 2003

In competitive electricity markets, each GenCo establishes generator maintenance schedule and submits to ISO those. Then, ISO reviews and arranges maintenance schedule of each GenCo to meet the standard for reliability. This paper presents the new optimization model which can apply to competitive electricity markets. The object of this model is to minimize schedules variation of each GenCo and to satisfy system reliability.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.27-34
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• 2002

In the case of reinforced concrete structures, the knowledge of load transfer in the long-term behavior analysis considering construction sequence is very important. Even though long-term behavior of concrete structures has been widely studied, the studies on the time-dependent axial force variation of shore have been scarce to date. In order to investigate the shore behaviors under actual construction conditions, a three-story test frame was constructed on a construction site. The entire construction schedule for the test frame was made to follow the schedule of an actual three-story frame. To analyze the data collected from the test frame, an analysis method based on the Winkler foundation model was developed. This analysis method accurately Predicts the time-dependent behavior of shore. The analysis results coincide well with those obtained by the Midas GENw program

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.1-16
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• 1997

This paper improves the autonomy for supplier's schedule and the flexibility of the final assembly line. The final assembly line is a single work station and each product taking different assembly time is considered. In the assembly schedule, the heuristic method based on the goal chasing method is used. Consequently, suppliers can independently determine their output rates and thus, change their workload pattern according to their needs and priorities. Moreover, this flexibility can help to avoid expensive final-assembly-line stoppages in case of sudden part supply disruptions. The sequencing method can be easily implemented into an existing just-in-time system. In addition, the mathematical model was formulated and the algorithm was explained through the flow chart. The numerical example was given and the efficiency of this method is shown through the analysis of computational results of that example.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.75-85
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• 2003

With recent advances in technology and the changing nature of business, call center management has become a rapidly growing industry. However theoretical analysis about the call center system is very difficult, and the forecasting of call volume also. In the situation, it is significant that we study call-flow system, design system model and perform simulation. If these are possible, it is able to control the staff schedule and the resource management efficiently. This study introduces the process of applying the call center to simulation. So, it is feasible to break from the intuitive management by a minority manager and analyze it scientifically. The enterprise can reduce unnecessary expense, make an offer high quality to user in a keen competition

• International conference on construction engineering and project management
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• 2009.05a
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• pp.835-840
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• 2009

Lately, Building Information Modeling (BIM) emerges as the most promising technology, now is expected to bring a great deal of improvement of productivity in every aspect of the construction industry. One of the BIM based scheduling is to use BIM model as a base for applying to schedule analysis and simulation tools. This type of tools may incorporate a various types of information such as the building model, construction method information, resource information, productivity information, rules and constraints to optimize activity sequencing. This paper proposes a framework of BIM based simulating system which can be used to optimize construction processes, especially for the floor construction cycle. For the purpose, all of the necessary components of the system will be defined and represented, and next an algorithm will be introduced to demonstrate the principle of simulating operation. The benefits of this technique are basically two : to test and optimize construction methods in respect of the construction duration and to reduce the floor construction cycle.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.780-785
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• 2005

This paper aims to consider an overall benefit-duration optimization (OBDO) problem for the sake of maximizing owner's economic benefits, whilst considering influences of schedule compression incurred opportunity income on the profitability of a large-scale construction project. Unlike previous schedule optimization models and techniques that have focused on project duration or cost minimization, with greater weight on contractors' interests, OBDO facilitates owner's economic benefits through overall benefit-duration optimization. In this paper, the objective function of OBDO model is formulated. An example is illustrated to prove the feasibility and practicability of the overall benefit-duration optimization problem. The significance of employing OBDO model and future research work are also described.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.3
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• pp.117-124
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• 1994

In this paper an inventory model is presented for determining the ordering schedule in which the demand rate is changing linearly with time and the decay is assumed to be a constant rate of the on-hand inventory. An easy to use heuristic is developed to find the times and sizes of replenishments so as to keep the total of ordering, inventory carrying and deteriorating costs as low as possible. Solutions of the model to test problems show that our heuristic model outperforms other existing models in the literature without sacrificing the computational complexity. When there is no deterioration, the model developed is related to the corresponding model of nondeteriorating items.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.46-53
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• 1999

As of July 1999, i,185 lomocotives(excluding metropolitan area electric locomotives) are in Korean National Railroad(KNR). With this limited number of resources assigning locomotives to each trains of timetable is very important in the entire railway management point of view because schedule can be regarded as goods in transportation industry. On a simple rail network, it is rather easier to assign proper locomotives to trains with the experience of operating experts and get optimal assignment solution. However, as the network is getting bigger and complicated, the number of trains and corresponding locomotives will be dramatically increased to rover all the demands required to service all of the trains in timetable. There will be also numerous operational constraints to be considered. Assigning proper locomotives to trains and building optimal cyclic rotations of locomotive routings will result in increasing efficiency of schedule and giving a guarantee of more profit. The purpose of this study is two fold: (1) we consider a planning-level locomotive scheduling problem with the objective of minimizing the wasting cost under various practical constraints and (2) development of implementation prototype program of its assigning result. Not like other countries, i.e. Canada, Sweden, Korean railroad operates on n daily schedule basis. The objective is to find optimal assignment of locomotives of different types to each trains, which minimize the wasting cost. This problem is defined on a planning stage and therefore, does not consider operational constraints such as maintenance and emergency cases. Due to the large scale of the problem size and complexity, we approach with heuristic methods and column generation to find optimal solution. The locomotive scheduling prototype consists of several modules including database, optimization engine and diagram generator. The optimization engine solves MIP model and provides an optimal locomotive schedule using specified optimization algorithms. A cyclic locomotive route diagram can be generated using this optimal schedule through the diagram generator.

• Korean Journal of Construction Engineering and Management
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• v.16 no.6
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• pp.53-62
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• 2015

Time-Cost Trade-Off (TCTO) model is an important model in the construction project planning and control area. Two types of Existing TCTO model, continuous and discrete TCTO model, have been developed by researchers. However, Using only one type of model has a limitation to represent a realistic crash scenario of activities in the project. Thus, this paper presents a comprehensive TCTO model that combines a continuous and discrete model. Additional advanced features for non-linear relationship, incentive, and liquidated damage are included in the TCTO model. These features make the proposed model more applicable to the construction project. One CPM network with 6 activities is used to explain the proposed model. The model found an optimal schedule for the example to satisfy all the constraints. The results show that new model can represent more flexible crash scenario in TCTO model.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.349-356
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• 2002

This paper describes a mathematical programming model for constructing the rolling stock assignment plan. This plan is a schedule which assigns daily routings, maintenance activities, and other tasks to trainsets. A generalized set partitioning model which is a kind of integer programming model is suggested as a model for constructing the assignment plan. And a column generation method are suggested as a solution method.