• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.371-374
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• 1998

The construction of the transportation history database system is to serve the scheduling and seat inventory controling. Recently, lots of countries have been faced with the advance era because of the new railway transportation system, like the high speed railway and/or magnetic levitation vehicle system. This can be reasonably translated as those of operators are willing to provide the more various and high quality schedule to the customer. Those operators these ideas make possible to forecast that scheduling process is going to be complicated more and more. The seat inventory control, so to speak Yield Management System(YMS), goes a long way to improve the total passenger revenue at the railway business. The YMS forecasts the number of the last reservation value(DCP# END) and recommends the optimal values on the seat sales. The history database system contains infra-data(ie, train, seat, sales) that will be the foundation of scheduling and seat inventory control application programs. The development of the application programs are reserved to the next step. The database system is installed on the pc platform (IBM compatible), using the DB2(RDBMS). And at next step, the platform and DBMS will be considered whether they can meet the users' requirement or not.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.558-564
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• 2007

3G Long Term Evolution, which aims for various mobile multimedia service provision by enhanced wireless interface, proposes VoIP-based voice service through a Packet Switching (PS) domain. As delay and loss-sensitive VoIP traffic flows through the PS domain, more challenging technical difficulties are expected than in Circuit Switching (CS) domain based VoIP services. Moreover, since 3G LTE, which adopts the OFDM as its physical layer, introduces Physical Resource Block (PRB) as a unit for transmission resources, new types of resource management schemes are needed. This paper proposes a PRB scheduling algorithm of MAC layer for VoIP service in 3G LTE and shows the simulation results. The proposed algorithm has two key parts; dynamic activation of VoIP priority mode to satisfy VoIP QoS requirements and adaptive adjustment of the priority mode duration in order to minimize the degradation of resource utilization.

• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.12
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• pp.976-985
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• 2018

Modern radars such as the phase array radar can handle various tasks by generating a beam from a phased array antenna. Radar can be used for miscellaneous applications such as surveillance, tracking, missile guidance etc. Previous radar systems could handle only one task at a time. As such, multiple radars were required to perform simultaneous tasks. Multi-function radars can perform many tasks using only one radar system. However, the radar's resources are limited in this instance. To efficiently utilize time, it is necessary to properly schedule tasks in the radar's timeline. In this report, we investigate the efficiency of different scheduling tasks.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.238-247
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• 2018

This paper considers the problem of scheduling loading and unloading operations of a crane in a railway terminal motivated from rail-road container transshipment operations at Uiwang Inland Container Depot (ICD). Unlike previous studies only considering the total handling time of containers, this paper considers a bi-criteria objective of minimizing the weighted sum of the total handling time and tenant service time. The tenant service time is an important criterion in terms of terminal tenants who are private logistics companies in charge of moving containers from/to the terminal using their trucks. In the rail-road container shipment yard, the tenant service time of a tenant can be defined by a time difference between beginning and finishing loading and unloading operations of a crane. Thus, finding a set of sequences and time of the crane operations becomes a crucial decision issue in the problem. The problem is formulated as a nonlinear program which is improved by linearizing a nonlinear constraint in the model. This paper develops a genetic algorithm to solve the problem and performs a case study on the Uiwang ICD terminal. Computational experiment results show that the genetic algorithm shows better performance than commercial optimization solvers. Operational implications in terms of tenants are drawn through sensitivity analyses.

• International Journal of Computer Science & Network Security
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• v.21 no.1
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• pp.137-142
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• 2021

The Internet of Things (IoT) paradigm is at the forefront of present and future research activities. The huge amount of sensing data from IoT devices needing to be processed is increasing dramatically in volume, variety, and velocity. In response, cloud computing was involved in handling the challenges of collecting, storing, and processing jobs. The fog computing technology is a model that is used to support cloud computing by implementing pre-processing jobs close to the end-user for realizing low latency, less power consumption in the cloud side, and high scalability. However, it may be that some resources in fog computing networks are not suitable for some kind of jobs, or the number of requests increases outside capacity. So, it is more efficient to decrease sending jobs to the cloud. Hence some other fog resources are idle, and it is better to be federated rather than forwarding them to the cloud server. Obviously, this issue affects the performance of the fog environment when dealing with big data applications or applications that are sensitive to time processing. This research aims to build a fog topology job scheduling (FTJS) to schedule the incoming jobs which are generated from the IoT devices and discover all available fog nodes with their capabilities. Also, the fog topology job placement algorithm is introduced to deploy jobs into appropriate resources in the network effectively. Finally, by comparing our result with the state-of-art first come first serve (FCFS) scheduling technique, the overall execution time is reduced significantly by approximately 20%, the energy consumption in the cloud side is reduced by 18%.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.274-277
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• 2003

The Theory of Constraints (TOC) is an approach and a philosophy that is used to develop specific management techniques. It was first popularized by the novel, The Goal, that applied the principles to operations management. Since 1997 it has found application in two areas within project management. The first application is scheduling of a single project to reduce project duration and simplify project control. there is a further application to allocate resources that are shared by concurrent project. It is the objective of this paper to explore the fundamentals of critical chain and to pursue an application of critical chain method to construction project by a case study.

• Journal of Construction Engineering and Project Management
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• v.4 no.4
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• pp.47-59
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• 2014

Client organization inadequate project planning before awarding the contract and insufficient monitoring and control system among the parties involved create severe problems. Ultimately, large-scale projects go beyond the expected cost and time control limits. This paper discusses the major issues involved with a large-scale Hydropower Project in Pakistan Public Sector environment. The latest approved Baseline Plan of project was reviewed and analyzed using Variance Analysis and Trend Analysis techniques in Primavera project management software to assess the efforts made of the parties involved. It was found that Project is 202% Cost overrun and 25% time delays from original contract award. After analysis of baseline plan and quantification of various variance issues in impacted activities, the questionnaire survey was conducted to identify the impact of causative factors. There were almost 17 most significant causative factors identified among 60 identified factors and responsibilities are assigned accordingly. At the end recommendations are made for strategic decisions as lessons learned during project evaluation.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.682-686
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• 2007

Construction project has been more complex and bigger as various demands of the times. But current schedule management method in construction project uses only PERT or CPM made in 1950s without innovation. Also current schedule management focuses on not information flow between activities and variability of information exchanged but result. This paper suggest using the DSM(Dependency Structure Matrix) in schedule management of construction project to overcome limitations of current scheduling tools. DSM has been introduced as a new theory in construction industry in 1990s at the United States, but its application is still insufficient in domestic field due to the absence of systematic study.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1254-1254
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• 2022

The Multi-family Residential is one of the most famous building types for a rental property in the US. Often times it includes multiple residential buildings and some amenity facilities, including a clubhouse or leasing office, swimming pool, dog park, and garages. Since the building type is built for rental purposes, the construction planning is phased and it makes the project complicated. Detailed planning and execution are important for successful construction management. This paper provides some management practices that are applied to one of the multi-family residential construction projects in Phoenix, AZ. The Front End Planning (FEP) process performed by both owner and contractor is the first key to a successful construction project. Specifically, the early review of phased turnover strategy, grading, fire/Americans with Disabilities Act (ADA) compliance, and Mechanical/ Electricity/Plumbing/Technology (MEPT) will provide absolute benefit to the project. Second, using a scheduling method to control short-term schedules and long-term can provide the ability to manage the issues with agility. Third, material delivery and procurement dominate the both project schedule and cost. With this COVID-19 circumstance, it is hard to expect the material, equipment, and labor forces to be delivered on time with the contracted price. Managing floats are more than important to managing construction productivity. Risk management should work to share the risks fairly. Lastly, turnover is directly linked with the profit of the project for both owner and contractor. The communication between the owner and contractor to re-schedule the proper turnover schedule is important for the phased construction project.