• Journal of Institute of Control, Robotics and Systems
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• v.3 no.4
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• pp.398-405
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• 1997

This article presents a new model which is called Periodic Square-Wave(PSW) to describe the material flow of the periodic processes involving intermediate buffer. The material flows incoming into and outgoing from the intermediate buffer are assumed to be periodic square shaped. PSW model gives the same result as that of Economic Production Quantity(EPQ) model for determining optimal lot size of single stage batch storage system. However, for batch storage serial train system, PSW model gives a different optimal solution of about 6 % reduced total cost. PSW model provides the more accurate information on inventory and production system than the classical approach by maintaining simplicity and increasing computational burden.

• Journal of the Korean Society of Safety
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• v.10 no.1
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• pp.64-73
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• 1995

A preliminary study is performed in order to design an effective ventilation equipment for the control of possible pollutants in a workshop. To this end, the Patankar's SIMPLE methodology is used to investigate the flow characteristics of the contaminated thermal deflected jet which is encounted often in practical hood system. SIMPLE-Consistent algorithm is employed for the pressure-velocity coupling appeared in momentum equations. A two equation, k-$\varepsilon$ model is used for Reynolds stresses. The prediction data is compared well against the experimental results by Chang(1989). Considering the control of the wake due to its high turbulence together with the stagnant feature has been investigated in term of major parameters such as temperature and magnitude of the discharge velocity. Detailed discussions are made to reduce the size of the wake region which give rise to pollutant concentration stratification.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.821-831
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• 2006

In this paper we researched on the development methods and design of the B-ISDN protocol embedded Internet-Phone PBX System for the previous telephone exchange and communication. We designed the structure of the user terminal md exchange server of the Internet-Phone PBX System, defined message and data structure for call control, and designed call control message flows between sender and receiver terminal for user's communication.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.922-929
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• 2006

In this study, flow characteristics of the FPN (Fountain Pen Nano-Lithography) using active membrane pumping are investigated. This FPN has integrated chamber, micro channel, and high capacity reservoir for continuous ink feed. The most important aspect in this probe provided control of fluid injection using active membrane pumping in chamber. The flow rates in channel by capillary force are theoretically analyzed, including the control of mass flow rates by deflection of membrane. The above results are compared with numerical simulations that calculated by commercial code, FLUENT. The velocity of fluid in micro channel shows linear behaviors. And the mass flows are proportional to the second order function of pumping pressure that is imposed to membrane.

• Journal of Ship and Ocean Technology
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• v.8 no.4
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• pp.10-16
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• 2004

A response of a swept wing boundary layer to a single free-stream stationary axial vortex of a limited spanwise extent is considered as an example of typical problems that one can find in laminar-turbulent transition research and control. The response is dominated by streamwise velocity perturbations that grow quasi-exponentially downstream. It is shown that the formation of the boundary layer disturbance occurs for the most part close to the leading edge. The disturbance represents itself a wave packet consisted of the waves with characteristics specific for cross-flow instability. However, an admixture of growing disturbances whose origin can be attributed to transient effects and to a distributed receptivity mechanism is also identified.

• International Journal of Control, Automation, and Systems
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• v.6 no.2
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• pp.278-281
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• 2008

Linear motor (LM) based shuttle cars will play an important role in the future transportation systems of marine terminals to cope with increasing container flows. These systems are known as agile port terminals because of their significant advantages. However, routing for multiple shuttle cars is still an open issue. We present a network model of a container yard and propose constrained dynamic programming (DP) for its routing strategy with collision avoidance. The algorithm is a modified version of typical DP which is used to find an optimal path for a single traveler. We evaluate the new algorithm through simulation results for three shuttle cars in a mesh-type container yard.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1209-1214
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• 2006

This paper presents an application of Dividing Wall Column(DWC) to the recovery of the waste solvent from the film making processes. The waste solvent feed contains MEK(Methyl-Ethyl-Ketone), Toluene, Cyclohexanone, and water. The commercial software $HYSYS^{TM}$ was used for rigorous simulation and analysis. Sensitivity analysis for several major design variables were carried out to achieve the optimal design of the process. Distribution of the internal vapor and liquid flows to the prefractionator and main sections is shown to be the most dominant design factor for energy saving efficiency in the DWC process. The simulation results also show that the solvent recovery process using the DWC significantly improves both the energy efficiency and the compactness of the solvent recovery process.

• International Journal of Control, Automation, and Systems
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• v.5 no.3
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• pp.317-323
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• 2007

Quality of Service (QoS) in the Internet depends on queuing and sophisticated scheduling in routers. In this paper, we address the issue of managing traffic flows with different priorities. In our reference model, incoming packets are first classified based on their priority, placed into different queues with different capacities, and then multiplexed onto one router link. The fuzzy nature of the information on Internet traffic makes this problem particularly suited to fuzzy methodologies. We propose a new solution that employs a fuzzy inference system to dynamically and efficiently schedule these priority queues. The fuzzy rules are derived to minimize the selected Lyapunov function. Simulation experiments show that the proposed fuzzy scheduling algorithm outperforms the popular Weighted Round Robin (WRR) queue scheduling mechanism.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.2
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• pp.94-102
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• 2012

There have been many homing navigation algorithms for robotic system. In this paper, we suggest a bio-inspired navigation model. It builds path integration based on optical flow. We consider two factors on robot movements, translational movement and rotational movement. For each movement, we found distinguishable optical flows. Based on optical flow, we estimate ego-centric robot movement and integrate the path optimally. We can determine the homing direction and distance. We test this algorithm and evaluate the performance of homing navigation for robotic system.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.313-322
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• 2006

We consider a power controlled code division multiple access (CDMA) system with multiple flow types. At each of the N nodes, there are F flow types with different signal-to-interference-and-noise-ratio (SINR) requirements. To keep the complexity of the transmitter low, we assume that each node uses the same power level for all its flows. The single flow case has been fully solved and is well-understood. We concentrate on the multiple flow case, and use a novel and different approach. For the uplink problem with N = 2 and F arbitrary, the necessary and sufficient conditions to have a solution are found and proved. For the general N > 1 uplink problem, we provide a necessary condition for the problem to have a solution and an iterative algorithm to find the optimum solution. For the downlink case with F > 1 some properties of the optimal sequences are obtained.