• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.119-126
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• 2009

A district energy system plays very important role to fulfill energy demand in regional areas. This paper diagnoses the necessity of the development of an economical operation system for the efficient operation of district energy plants located in Seoul. The effect anticipated from the use of the optimal operation system is also analyzed. Production and consumption of energy are estimated for the district energy plants at Suseo, Bundang, Ilwon and Jungang located near in Seoul, Korea. The problem is formulated as a mixed integer linear programming(MILP) problem where the objective is to minimize the overall cost of the district energy system. From the results of numerical simulations we can see that the energy efficiency is improved due to the application of the optimal operation conditions provided by the proposed model.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.6
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• pp.692-697
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• 2003

The researches on the Internet based tole-operation have received increased attention for the past few years. In this paper, we implement the Internet based tele-operating system. In order to transmit robustly the surroundings and control information of the robot, we make a data as a packet type. Also in order to transmit a very large image data, we use PEG compressive algorithm. The central problem in the Internet based tele-operation is the data transmission latency or data-loss. For this specific problem, we introduce an autonomous mobile robot with a 2-layer fuzzy controller. Also, we implement the color detection system and the robot can perceive the object. We verify the efficacy of the 2-layer fuzzy controller by applying it to a robot that is equipped with various input sensors. Because the 2-layer fuzzy controller can control robustly the robot with various inputs and outputs and the cost of control is low, we hope it will be applied to various sectors.

• Journal of KIISE:Databases
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• v.37 no.3
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• pp.171-175
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• 2010

This paper analyzes the tag data inconsistency problem caused by incomplete execution of the tag access operation to the RFID tag's memory and proposes a protocol to control consistent tag data accesses with finalizing the incomplete operation. Passive RFID tag cannot guarantee complete execution of the tag access operations because of uncertainty and unexpected disconnection of RF communications. This leads to the tag data inconsistency problem. To handle this, we propose a concurrency control protocol which defines incomplete tag operations as continuous queries and monitors the tags're-observation continuously. The protocol finalizes the incomplete operation when the tag is re-observed while it blocks inconsistent data accesses from other operations. We justify the proposed protocol by analyzing the completeness and consistency. The experiments show that the protocol shows better performance than the traditional lock-based concurrency control protocol.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.4_2
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• pp.943-951
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• 2024

This paper considers the simulation-based installation and operation safety analysis of installation and operation machinery of USBL as underwater equipment in operation environments. The simulation model of this mechanical system was developed using flexible multibody dynamics simulation technology. Operation and environmental conditions were applied using dynamic forces model considering ocean environments. The developed simulation model was used to evaluate operation safety through eigenvalue analysis, dynamic forces analysis, and structural analysis. As the analysis results, the operation safety was very low in extreme operation condition due to increase of dynamic loads by VIV effect. It was not a problem because safety factor had more than 2.0 in this case. However, the operation safety should be further strengthened because the USBL and LARS was installed and utilized in unmanned vessel with automatic controls. In order to improve safety by avoiding VIV frequency, we redesigned the USBL pole.

• Journal of the military operations research society of Korea
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• v.36 no.1
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• pp.15-27
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• 2010

Fire sequencing problem is to find a sequence of firing on the targets. The latest, because the korea artillery force is inferior in number as compared with north korea force. It is an important question to give a fatal damage to the enemy force by using prompt and accurate fire in order to overcome the lack of artillery force. Minimizing the fire finishing time will secure the adapt ability in tactical operation. In this paper, we developed a mathematical model to do allocation the fire on the targets to decrease to total fire operation time. In order to work out the fire sequencing problem, MIP is developed and the optimum solution is obtained by using ILOG OPL. If this analytical model is applied to the field artillery unit, it will improve the artillery fire force enhancement.

• Korean Journal of Construction Engineering and Management
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• v.14 no.6
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• pp.30-37
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• 2013

Idea creation is the most important step in the overall value engineering (VE) process. Usually the activity is done mostly relying on the experience and knowledge of the experts in the VE team. A more organized approach is needed to find the chance of design improvement during a VE workshop. This study presents an organized approach to increasing the chance of idea creation during the VE workshop. The concept of conflict resolution in TRIZ (Theory of Inventive Problem Solving) is applied to understand the problem area during design improvement. The technical parameters were identified in the problem area to explain the conflicts in design improvement. These technical parameters were used to assist problem solving and improve design functions. A case study was done on a temporary construction operation, and demonstrated that the organized idea creation can help improve the design value of the temporary construction operation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.12C
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• pp.1215-1227
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• 2002

This paper presents a genetic algorithmic approach to shortest path (SP) routing problem. Variable-length chromosomes (strings) and their genes (parameters) have been used for encoding the problem. The crossover operation that exchanges partial chromosomes (partial-routes) at positionally independent crossing sites and the mutation operation maintain the genetic diversity of the population. The proposed algorithm can cure all the infeasible chromosomes with a simple repair function. Crossover and mutation together provide a search capability that results in improved quality of solution and enhanced rate of convergence. Computer simulations show that the proposed algorithm exhibits a much better quality of solution (route optimality) and a much higher rate of convergence than other algorithms. The results are relatively independent of problem types (network sizes and topologies) for almost all source-destination pairs.

• Korean Journal of Child Studies
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• v.26 no.5
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• pp.281-295
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• 2005

The study investigated cognitive and creative characteristics related to creative problem solving of intellectually gifted and average children. Fourth and 6th graders from elementary schools in I and B cities and gifted classes in K and I cities were administered the KEDI group IQ test and categorized into gifted(above IQ 125) and average(IQ 90-109) groups. A total of 371 children were selected through this procedure and were tested on formal operational tasks, general metacognitive knowledge, creativity characteristics scales, and creative problem solving tasks. Gifted children were superior to average children on all cognitive and creativity characteristics. For the gifted, grade and metacognition were significant predictors of creative problem solving in the verbal area, and all cognitive and creativity characteristics were significant predictors in the math area. For the average children, grade and metacognition were significant predictors of creative problem solving in the verbal area, and only grade was a significant predictor in the math area.

• Journal of Korean Institute of Industrial Engineers
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• v.37 no.1
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• pp.19-29
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• 2011

Cellular network is comprised of several base stations which serve cellular shaped service area and each base station (BS) is connected to the mobile switching center (MSC). In this paper, the configuration modeling and algorithm of a cellular mobile network with the aim of minimizing the overall cost of operation (handover) and network installation cost (cabling cost and installing cost of mobile switching center) are considered. Handover and cabling cost is one of the key considerations in designing cellular telecommunication networks. For real-world applications, this configuration study covers in an integrated framework for two major decisions: locating MSC and assigning BS to MSC. The problem is expressed in an integer programming model and a heuristic algorithm based on Lagrangian relaxation is proposed to resolve the problem. Searching for the optimum solution through exact algorithm to this problem appears to be unrealistic considering the large scale nature and NP-Completeness of the problem. The suggested algorithm computes both the bound for the objective value of the problem and the feasible solution for the problem. A Lagrangian heuristics is developed to find the feasible solution. Numerical tests are performed for the effectiveness and efficiency of the proposed heuristic algorithm. Computational experiments show that the performance of the proposed heuristics is satisfactory in the quality of the generated solution.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.537-540
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• 2000

The Distribution System consist of many tie-line switches and sectionalizing switches, operated a radial type. When an outage occurs in Distribution System, outage areas are isolated by system switches, has to restored as soon as possible. At this time, system operator have to get a information about network topology for service restoration of outage areas. Therefore, the searching result of restorative topology has to fast computation time and reliable result topology for to restore a electric service to outage areas, equal to optimal switching operation problem. So, the problem can be defined as combinatorial optimization problem. The service restoration problem is so important problem which have outage area minimization, outage loss minimization. Many researcher is applying to the service restoration problem with various techniques. In this paper, advanced Dijkstra algorithm is applied to searching a restoration topology, is so efficient to searching a shortest path in graph type network. Additionally, fuzzy rules and operator are applied to overcome a fuzziness of correlation with input data. The present technique has superior results which are fast computation time and searching results than previous researches, demonstrated by example distribution model system which has 3 feeders, 26 buses. For a application capability to real distribution system, additionally demonstrated by real distribution system of KEPCO(Korea Electric Power Corporation) which has 8 feeders and 140 buses.