• Korean Management Science Review
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• v.17 no.2
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• pp.67-73
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• 2000

This paper describes a scheduling support system for a plant where the machine environment may be modeled as non-identical parallel machine lines (NPML). That is, there are a number of stages in series with various different-capability-machines at each stage. Arriving continuously are jobs with their specific due dates, processing times and candidate processing machines. We’ve developed a real-time scheduling module in conjunction with a supporting production information system which supplies necessary data to the module. This scheduling module is one of the 9 modules in this system, and is composed of both a scheduling interface and a production monitoring interface. This module allows users to generate many candidate schedules by selecting their business policies. The selective arguments which are available consist of allocation costs, batch sizes and machine selection intervals. They are now being implemented at a powder metallurgy plant.

• Journal of Power System Engineering
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• v.16 no.1
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• pp.84-90
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• 2012

In unmanned vehicles' navigation, the shapes of obstacles are generally irregular and complex. The motion of vehicles based on the range sensor system such as ultrasonic sensors or laser sensors can be unstable due to the irregular shape of the obstacles. In this case, to generate stable trajectory of unmanned vehicles equipped with range sensors, we need an approach that can simplify an obstacle's irregular shape information. In this paper, we propose the trajectory generation algorithm that an vehicle can stably navigate in the environments where irregular shaped obstacles are scattered. The proposed method is verified through the analysis of vehicle's trail and direction data acquired by simulations and implementations.

• Journal of applied mathematics & informatics
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• v.28 no.1_2
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• pp.439-450
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• 2010

In this paper, we propose a new idea to evaluate the prediction accuracy of user's preference generated by memory-based collaborative filtering algorithm before prediction process in the recommender system. Our analysis results show the possibility of a pre-evaluation before the prediction process of users' preference of item's transaction on the web. Classification functions proposed in this study generate a user's rating pattern under certain conditions. In this research, we test whether classification functions select users who have lower prediction or higher prediction performance under collaborative filtering recommendation approach. The statistical test results will be based on the differences of the prediction accuracy of each user group which are classified by classification functions using the generative probability of specific rating. The characteristics of rating patterns of classified users will also be presented.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1136_1138
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• 2009

This paper gives a basic Energy performance data of micro gas turbine and Renewable Energy(BIPV and Solar Collector System) installed in Hospital Building. The efficiency of solar collector and BIPV system was 30%, 10% individually, and lower than micro gas turbines. Micro gas turbines are small gas turbines that burn gaseous and liquid fuels to produce a high-energy exhaust gas and to generate the electrical power. Recently the size range for micro gas turbines is form 30 to 500kW and power-only generation or in combined heat and power(CHP) systems. If micro gas turbine was operated only for electric energy, the efficiency was about 30%, but for combined heat and power, the efficiency was about 90%. Finally, installed in large hospital, Micro gas turbine system was operated to CHP mode, was high-efficiency system than Solar collector and BIPV system.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.107_108
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• 2009

In this paper, a fault section detection algorithm to be considered variety measurement devices is proposed in ungrounded diatribution network. Ungrounded network is different from grounded netork. It's that a fault current doesn't generate when a single grounded fault by characteristic of ungrounded network. So, a fault section detection is very difficult. Thus, in this paper, a fault section detection method is proposed by data from variety measurement devices. The method is proved by matlap simulink.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1105-1109
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• 1995

A CCD-camera, which is structured with vision system, was used to realize automatic seam-tracking system and 3-D information which is needed to generate torch path, was obtained by using laser-slip beam. To extract laser strip and obtain welding-specific point, Adaptive Hough-transformation was used. Although the basic Hough transformation takes too much time to process image on line, it has a tendency to be robust to the noises as like spatter. For that reson, it was complemented with Adaptive Hough transformation to have an on-line processing ability for scanning a welding-specific point. the dead zone,where the sensing of weld line is impossible, is eliminated by rotating the camera with its rotating axis centered at welding torch. The camera angle is controlled so as to get the minimum image data for the sensing of weld line, hence the image processing time is reduced. The fuzzy controller is adapted to control the camera angle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.397-401
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• 1995

ESPI(Electronic Speckle Pattern Interfermetry) is an optical technique to measure surface deforamtion of engineering components and materials in industrial ares. This optical method is capable of providing full-field results with high spatial resolution, high speed and is the non-contact technique. One of important application aspects using electronic speckle pattern interferometry is to generate contours of a diffuse object in order to provide data for 3-D shape analysis and topography measurement. The contouring method by modified dual-beam speckle pattern interferometry is proposed. We introduce a shift of the illumination beams through optical fiber in order to obtain the contour fringe patterns. The speckle pattern correlation technique is suitable for providing measurement range from millimeters to several centimeters. The complete geometric analysis of the contoretical and experimental results are obtained.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.205.2-205.2
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• 2011

Micro hydraulic turbines take a growing interest because of its small and simple structure as well as high possibility of applying to micro and small hydropower resources. The differential pressure exiting within the city water pipelines can be used efficiently to generate electricity like the energy generated through gravitational potential energy in dams. In order to reduce water pressure at the inlet of water cleaning centers, pressure reducing valves are used widely. Therefore, pressure energy is wasted. Instead of using the pressure reduction valve, a micro counter-rotating hydraulic turbine can be replaced to get energy caused by the large differential pressure found in the city water pipelines. In this study, in order to acquire design data of counter-rotating tubular type micro-turbine, output power, head, and efficiency characteristics due to the diffuser.

• Tribology and Lubricants
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• v.5 no.2
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• pp.94-100
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• 1989

Friction and Wear behavior of continuous graphite fiber composites was studied for different fiber orientations against the sliding direction. The effect of fiber orientation on friction and wear of the composite and on the deformation of the counterface was investigated experimentally. Pin on disk type testing machine was built and employed to generate the friction and wear data. A graphite fiber composite plate was produced by the bleeder ply molding in an autoclave and machined into rectangular pin specimens with specific fiber orientations, i.e., normal, transverse, and longitudinal directions. Three different wear conditions were employed for two different periods of time, 24 and 48 hours. The wear track of the worn specimens and the metal counterface was examined with a scanning electron microscope (SEM) to observe the damaged fibers on the surface and wear film generation on the counterface. Wear mechanism of the composite during sliding wear is proposed based on the experimental results.

• Korean Management Science Review
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• v.21 no.1
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• pp.39-55
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• 2004

Efficient crew scheduling for cockpit crew is important in airline industry due to operational safety and cost associated with the flight duty time. Because of complexity of regulations imposed to the cockpit crew. it is complicated to generate an efficient schedule. Schedule of cockpit crew can be generated through two steps; selecting of flight patterns. and scheduling of them to the specific time horizon. Heuristic method is developed and applied with massive data in a limited time of computation. A set of flight patterns is selected from all possible flight patterns. which are generated by composing the flight leg based on regulations. by using the set partitioning problem with objective function of oversea stay cost. The selected set of flight patterns found at the first step is allocated to 4 week crew schedule to minimize the variance of total fight time assigned to each crew. The crew schedules obtained are evaluated and compared with the ones currently used in one of major airline company.