• Journal of the Korean Operations Research and Management Science Society
• /
• v.24 no.4
• /
• pp.63-80
• /
• 1999

In the container transportation of inland depots the empty container is an important issue. The truck dispatching problem in this paper is considered under restriction about empty containers. When a full container arrives in a depot by truck, after unloading operation the full container is changed to an empty container. After loading operation an empty container is changed to a full container. We suggest an integrated approach to the problem of simultaneously managing empty truck and container movements. We suggest an integrated approach to the problem of simultaneously managing empty truck and container movements. We would like to find the truck dispatching method minimizing empty truck movements and empty container movements. In this paper, a mixed integer programming model is developed to obtain the optimal truck dispatching in container transportation and heuristic is developed to give a good solution in much shorter time. The numerical examples are studied and the proposed heuristic is also compared with the result of numerical examples.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.23 no.2
• /
• pp.47-65
• /
• 1998

We consider a multiperiod capacity planning problem for determining a mix of flexible and dedicated capacities under budget restriction. These capacities are controlled by purchasing flexible machines and/or new dedicated machines and disposing old dedicated machines. Acquisition and replacement schedules are determined and operations are assigned to the flexible or dedicated machines for the objective of minimizing the sum of discounted costs of acquisition and operation of flexible machines, new dedicated machines, and old dedicated machines. In this research, the Problem is formulated as a mixed integer linear Program and solved by a Lagrangian relaxation approach. A subgradient optimization method is employed to obtain lower bounds and a multiplier adjustment method is devised to improve the bounds. We develop a linear programming based Lagrangian heuristic algorithm to find a good feasible solution of the original problem. Results of tests on randomly generated test problems show that the algorithm gives relatively good solutions in a reasonable amount of computation time.

• IE interfaces
• /
• v.23 no.2
• /
• pp.139-146
• /
• 2010

In this paper, we present the study of a real passenger transportation system. Passenger transportation problem aims to transport passengers from bus stops to their destinations by a fleet of vehicles while satisfying various constraints such as vehicle capacity, maximum allowable riding time in a bus, and time windows at destinations. Our problem also has special issues such as mixed loading, consideration of afternoon problem together with morning problem, and transferring passengers between vehicles. Our solution approach consists of three serial procedures: bus route generation, bus scheduling, and post optimization. Efficient heuristic algorithms were developed and implemented for the procedures. The proposed solution approach has been successfully applied to several real world problem instances and could reduce about 10% to 15% of buses.

• Proceedings of the KIEE Conference
• /
• 2006.10c
• /
• pp.416-418
• /
• 2006

In this paper, a new acoustic echo cancellation approach based on the DUET algorithm and scaling factor estimation is proposed to solve the scaling ambiguity in case of blind separation based acoustic echo cancellation in a noisy environment. In hands-free full-duplex communication system. acoustic noises picked up by the microphone are mixed with echo signal. For this reason, the echo cancellation system may provide poor performance. For that purpose, a degenerate unmixing estimation technique, adjusted in the time-frequency domain, is employed to separate undesired echo signals and noises. Also, since scaling and permutation ambiguities have not been solved in the blind source separation algorithm, kurtosis for the desired signal selection and a scaling factor estimation algorithm are utilized in this rarer for the separation of an echo signal. Simulation results demonstrate that the proposed approach yields better echo cancellation and noise reduction performances, compared with conventional methods.

• Journal of The Korean Astronomical Society
• /
• v.45 no.4
• /
• pp.101-110
• /
• 2012

I present here one approach to general relativistic radiation hydrodynamics. It is based on covariant tensor conservation equations and considers only the frequency-integrated total energy and momentum exchange between matter and the radiation field. It is also a mixed-frame formalism in the sense that, the interaction between radiation and matter is described with quantities in the comoving frame in which the interaction is often symmetric in angle while the radiation energy and momentum equations are expressed in the fixed frame quantities in which the derivatives are simpler. Hence, this approach is intuitive enough to be applied straightforwardly to any spacetime or coordinate. A few examples are provided along with caveats in this formalism.

• Journal of computational fluids engineering
• /
• v.18 no.2
• /
• pp.93-98
• /
• 2013

In this paper, we reported the verification of numerical simulation approach for sedimentation of the multi-size particles in a container. The comparison between experimentally measured values and numerically evaluated values on settle down process of fully mixed mixture is carried out. In an attempt to represent the natural particle size distribution, various diameters of single particles are simulated and the results are compared with the outcome of the multi-size computation. When the empirical formula for mean particle size estimation is adopted to define the sediment diameter, computation and comparison are conducted.

• Journal of Institute of Control, Robotics and Systems
• /
• v.5 no.6
• /
• pp.667-675
• /
• 1999

In this paper, we propose a robust controller design of RTP(Rapid Thermal Processing) system using structured uncertainty approach. Using the weighted mixed sensitivity function, we solve the robust stability problem against disturbance and temperature variation, and design a $\mu$ controller using curve fitting method against structured uncertainty. Also the reduction method should be requried because of the difficulty of implementaion with the obtained high order controller. We dal with robust stability and performance of RTP system by the design of $\mu$ controller for original model and Schur balanced reduced model. Finally the simulation results are proposed to show the validity of the proposed method.

• 한국전산유체공학회:학술대회논문집
• /
• 2011.05a
• /
• pp.10-13
• /
• 2011

A level set method is proposed to simulate the incompressible two-phase flow considering the effect of surface tension. For reinitialization of level set junction, a direct approach method is employed, instead of solving hyperbolic type equation. A mixed element is adopted, so that the continuity mid Navier-Stokes equations are solved by using the quadratic elements (six-node triangular element mid nine-node quadrilateral element), mid the level set function is solved by using the linear elements (three-node triangular element mid four-node quadrilateral element). In order to verify the accuracy mid robustness of the codes, the present methods are applied to a few benchmark problems. It is confirmed that the present results are in good qualitative mid quantitative agreements with the existing studies.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.137-140
• /
• 1999

This paper presents an application of the Genetic Algorithms(GA) to solve the optimal routing problem(ORP) in power distribution system planning. Since the ORP is, in general, modeled as a mixed integer problem with some various mathematical constraints, it is hard to solve. In this paper, a new approach was made using the GA method for the ORP to overcome the disadvantages which many conventional methods generally have. For this approach, proposed was in this study a appropriately designed fitness function suited for the ORP. The proposed algorithm has been tested in sample network and the results are presented.

• The Korean Journal of Pain
• /
• v.10 no.2
• /
• pp.250-253
• /
• 1997

The perineum is comprised of diverse anatomic structures with mixed sympathetic and somatic innervation. The coccyx is innervated by the coccygeal nerves and branches of the fifth sacral root. Recently, ganglion impar block has been introduced as an alternative means of managing intractable pain of sympathetic origin, coccygodynia by trauma, tenesmus and perineal hyperhydrosis. We managed a 59-year-old female patient who had suffered from perineal pain by metastasis of cervical cancer. Approach to impar ganglion through the anococcygeal ligament was impossible because her coccyx was hyperflexed anteriorly by old fracture. But we could perform ganglion impar block successfully by approach through the separation of sacrum and coccyx.