• Journal of Internet Computing and Services
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• v.16 no.6
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• pp.47-55
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• 2015

The conventional dynamic routing methods in Software Defined Networks (SDN) set the optimal routing path based on the minimum link cost, and thereby transmits the incoming or outgoing flows to the terminal. However, in this case, flows can bypass the middlebox that is responsible for security service and thus, thus the network can face a threat. That is, while determining the best route for each flow, it is necessary to consider a dynamic service chaining, which routes a flow via a security middlebox. Therefore, int this paper, we propose a new dynamic routing method that considers the dynamic flow routing method combined with the security service functions over the SDN.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.2
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• pp.126-137
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• 2003

The feasibility study of UV-disinfection system was performed for disinfection of effluent from wastewater treatment plant. Three low-pressure UV lamps of 17, 25, and 41 W were examined with various flow rates. Low-pressure UV lamps of 17W were examined with various turbidity, DOM (dissolved organic matter), and SS (suspended solid). The pilot plant was a flow-through type UV-disinfection system, and the range of exposure time varied from 5 to 40 seconds, turbidity from 0 to 40 NTU, DOM from 0 to 30 mg/L, and SS from 10 to 40 mg/L. The 41W lamp demonstrated complete disinfection showing no survival ratio in all the experimental conditions, and generally 17W and 25W lamps also showed high removal ratio over 97%. For the same UV dose (UV intensity times exposure time), high intensity-short exposure conditions showed better disinfection efficiency than low intensity-long exposure conditions. While the effects of turbidity and DOM were not apparent, the effects of SS was significant on the disinfection efficiency which indicates that SS control before UV-disinfection appears to be necessary to increase removal efficiency. Considering characteristics of effluent from existing wastewater treatment plants, cost-effectiveness, stable performance, and minimum maintenance, the flow-through type UV-disinfection system with high intensity and low-pressure lamps was thought to be a competitive disinfection system for wastewater reclamation.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.926-928
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• 1998

A fast optimization algorithm has been evolved from a simple two stage optimal power flow(OPF) algorithm for constrained power economic dispatch. In the proposed algorithm, we consider various constraints such as power balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the coupled LP based OPF method to an average gain of 53.13 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

• Journal of Digital Contents Society
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• v.3 no.2
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• pp.221-233
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• 2002

In this paper, we present integer programming models and algorithms for the Capacitated Facility Location-Allocation Problem (CFLP). The models and algorithms can be used for the design of logistics networks and for the location of telecommunication facilities. We are given a set of candidate facility installation sites, one type of facility for each candidate site with its capacity and installation cost, a set of customers with their demand requirement, and flow cost for one unit of demand flow from each customer to each candidate site. (CFLP) is to determine the number of facilities for each candidate site and the set of customers which are connected to each site with minimum cost, while satisfying the demand requirement of each customer and constraints imposed on the allocation of customers to facilities. We present two integer programming models for (CFLP), and devise a branch-and-cut algorithm and a branch-and-price algorithm for the problem.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.3
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• pp.86-94
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• 1990

This paper suggests a unified packet telecommunication network, which is designed by applying network design algorithm and distribution network design algorithm, Proposed local network design algorithm is based on MST topology, and it can satisfy the limited capacity and get a distribution effect of communication flow, With the result of the comparison with Kruskal and Esau-Willams algorithm, an increase of 2.7% in cost and a decrease of 44.8% in average delay time are shown. Starting with MST topology, proposed distribution network design algorithm gradually increases its reliability, and proposes a conclusive algorithm to determine a topology with minimum cost. In compared with Cut-Saturation algorithm in the aspect of end-to-end delay time and communication flow restricted condition, this proposed algorithm results in 1/7 cost down and about 2.5 times increases in Throughput.

• Journal of Korea Water Resources Association
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• v.49 no.5
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• pp.431-438
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• 2016

Large energy consumption is one of the main weaknesses of RO desalination. A new method is proposed to reduce the energy consumption of RO desalination which depends on the salinity of the feedwater. Low salinity feedwater can be obtained using groundwater wells which extracts both fresh groundwater and subsurface sea water. Subsurface feedwater is advantageous in overcoming other problems associated with surface seawater intakes. Salinities of groundwater depend on a number of factors. In this work a new simulation-optimization model is proposed to identify well locations and pumping rates with would provide the required design flow rate with the minimum salinity. When groundwater is developed in a coastal area, the saltwater wedge advances inland and may contaminate existing groundwater wells, which must be prevented. The model can protect existing wells while developing minimum salinity feedwater. Examples are provided to demonstrate the usage of the model.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.521-533
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• 2012

Interest in application of ultraviolet light technology for primary disinfection that used for the treatment of water for consumption and wastewater has increased significantly in recent years. Analysis of these systems has been carried out using Computational Fluid Dynamics (CFD) procedure. It offers advantages over other techniques in specific circumstances. CFD has emerged as a powerful tool to aid design of a UV reactor by providing the UV dose delivered by the proposed reactor design and allowing engineers to evaluate alternative designs in much less time and at a reasonable cost. In this study, five different configurations of the apparatus depending on the location of the exit are evaluated in terms of maximum dose, minimum dose, flow patterns, particle tracks and transient dose. The configuration 3 results have higher minimum UV dose value and uniform particle distribution of the UV dose on the outlet than other's.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.57-64
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• 2010

Metal Injection Molding (MIM) is attractive because it produces consistent, complex-geometry components for high-volume, high-strength, and high-performance applications. Also MIM using in optical communication field, display field, and semi-conductor field is a cost-effective alternative to metal machining or investment casting parts. It offers tremendous single-step parts consolidation potential and design flexibility. The objective of this paper is to study the suitability of design, flow analysis, debinding and sinterin processes, and capability analysis. The suitable injection conditions were 0.5~1.5 second filling time, 11.0~12.5 MPa injection pressure derived from flow analysis. The gravity of the product is measured after debinding an sintering. The maximum and minimum gravity levels are 7.5939 and 7.5097. the average and standard deviation are 7.5579 and 0.0122; when converted into density, the figure stands at 98.154%. According to an analysis of overall capacity, PPM total, which refers to defect per million opportunities(DPMO), stands at 166,066.3 Z.Bench-the sum of defect rates exceeding the actual lowest and highest limits-is 0.97, which translates into the good quality rate of around 88.4% and the sigma level of 2.47.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.574-575
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• 2007

This paper proposes a method for choosing the best transmission system expansion plan using nodal/bus delivery marginal rate criterion ($BMR_k$) defined newly in this paper. The objective method minimizes a total cost which is an investment budget for constructing new transmission lines subject to the $BMR_k$ which means a nodal deterministic reliability level requirement at specified load point. The proposed method models the transmission system expansion problem as an integer programming problem. It solves for the optimal strategy using a branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. Test results on an existing 21-bus system are included in the paper. It demonstrated the suitability of the proposed method for solving the transmission system expansion planning problem in competitive electricity market environment.

• Korean Journal of Remote Sensing
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• v.18 no.2
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• pp.107-116
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• 2002

A hybrid image segmentation algorithm is proposed which integrates edge-based and region-based techniques through the watershed algorithm. First, by using mean curvature diffusion coupled to min/max flow, noise is eliminated and thin edges are preserved. After images are segmented by watershed algorithm, the segmented regions are combined with neighbor regions. Region adjacency graph (RAG) is employed to analyze the relationship among the segmented regions. The graph nodes and edge costs in RAG correspond to segmented regions and dissimilarities between two adjacent regions respectively. After the most similar pair of regions is determined by searching minimum cost RAG edge, regions are merged and the RAG is updated. The proposed method efficiently reduces noise and provides one-pixel wide, closed contours.