• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1827-1835
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• 1996

This paper addresses the problem of a torch path generation for the 2D laser cutting of a stock plate nested with resular or irregular parts. Under the constaint of the relative positions of parts enforced by nesting, the developed torch path algorithm generate feasible cutting path. In this paper, the basic object is a polygon( a many-slide figure) with holes. A part may be represented as a number of line segments connected end-to-end in counterclockwise order, and formed a closed contour as requied for cutting paths. The objective is to tranverse this cutting contours with a minimum path length. This paper proposes a simulated annealing based dtorch path algorithm, that is an improved version of previously suggested TSP models. Since everypiercing point of parts is not fixed in advance, the algorithm solves as relazed optimization problem for the constraint, thich is one of the main features of the proposed algorithm. For aolving the torch path optimization problem, an efficient generation mechanism of neighborhood structure and as annealing shedule were introduced. In this way, a global solution can be obtained in a reasonable time. Seveeral examples are represented to ilustrate the method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11B
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• pp.972-984
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• 2003

In this paper, new on-line routing algorithms with a bandwidth constraint are proposed. The proposed algorithms may be used for a dynamic LSP setup in MPLS network. We extend the WSP algorithm, the SWP algorithm and a utilization-based routing algorithm into the proposed algorithms by slightly modified K-shortest loopless path algorithms. The performances such as accepted bandwidth, accepted request number and average path length of the proposed and the previous algorithms are evaluated through extensive simulations. All simulations are conducted under the condition that any node can be an ingress or egress node for a LSP setup. The simulation results show that the proposed algorithms have the good performances in most cases in comparison to the previous algorithms. Under the heavy load condition, the algorithms based on the minimum hop path perform better than any other algorithms.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.1
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• pp.29-35
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• 2004

Locomotive scheduling in railway systems experiences many difficulties because of the complex interrelations among resources, knowledge and various constraints. Artificial intelligence technology has been applied to solve these scheduling problems. These technologies have proved to be efficient in representing knowledge and rules for complex scheduling problems. In this paper, we have applied the CSP (Constraints Satisfaction Problems) programming technique, one of the AI techniques, to solve the problems associated with locomotive scheduling. This method is more effective at solving complex scheduling problems than available mathematical programming techniques. The advanced locomotive scheduling system using the CSP programming technique is realized based on the actual timetable of the Saemaul type train on the Kyong-bu line. In this paper, an overview of the CSP programming technique is described, the modeling of domain and constraints is represented and the experimental results are compared with the real-world existing schedule. It is verified that the scheduling results by CSP programming are superior to existing scheduling performed by human experts. The executing time for locomotive scheduling is remarkably reduced to within several decade seconds, something requiring several days in the case of locomotive scheduling by human experts.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.6
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• pp.714-723
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• 1999

This paper presents a short-term scheduling algorithm for the operation of steelmaking processes. The scope of the problem covers refining of the hot iron transferred form a blast furnace, ladle treatment, continuous casting, hot-rolling, and coiling for the final products that should satisfy the given demand. The processing time at each unit depends on how much the batch amount is treated, and te dedicated intermediate storage with finite capacity between the units is considered. Resource constraints and initial amount of each state are incorporated into the presented scheduling model for the algorithm of on-line scheduling. We propose amixed integer linear programming (MILP) model with two objectives for the scheduling. The first is to maximize the total profit while atisfying the due date constraint for each product. And the second is to minimize the total processing time, makespan, while satisfying the demand for each product. Especially, we observe the effect of penalizing the intermediate storage and the inventory level of the final product on the scheduling results.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.663-668
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• 1990

This paper deals with the application of a Generalized Predictive Control (CPC) to a Pressurized Water Reactor (P.W.R) Nuclear Power Plant. Generalized Predictive Control is a sort of Explicit Self-Tuning Control. Current self-tuning algorithms lack robustness to prior choices of either dead-time (input time delay of a plant) or model order. GPC is shown by simulation studies to be superior to accepted self-tuning techniques such as minimum variance and pole-placement from the viewpoint that it is robust to prior choices of dead-time or model order. In this paper a GPC controller is designed to control the P.W.R. nuclear power rlant with varying dead-time and through the designing procedure the designer is free from the constraint of knowing the exact dead-time. The controller is constructed based on the 2nd order linear model approximated in the vicinity of operating point. To ensure that this low-order model describes the complex real dynamics well enough for control purposes, model parameters are updated on-line with a Recursive Least Squares algorithm. Simulation results are successful and show the possibilities of the GPC control application to actual plants with varying or unknown dead-time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1418-1425
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• 2003

In CAD systems, a surface to be machined is expressed by a series of curves, such as B-spline, Bezier and NURBS curves, which compose the surface and then in CAM systems the curves are divided into a large number of line or arc segments. These divided movement commands, however, cause many problems including their excessive size of NC data that makes almost impossible local adjustment or modification of the surface. To cope with those problems, the necessity of real-time curve or surface interpolators was embossed. This paper presents an efficient real-time tool-path generation method fur interpolation of NURBS surfaces in CNC machining. The proposed tool-path generation method is based on an improved iso-scallop strategy and can provide better precision than the existing methods. The proposed method is designed such that tool-path planning is easily managed in real-time. It proposed a new algorithm for regulation of a scallop height, which can efficiently generate tool-paths and can save machining time compared with the existing method. Through computer simulations, the performance of the proposed method is analyzed and compared with the existing method in terms of federate, total machining time and a degree of constraint on the scallop height.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.6
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• pp.305-311
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• 2000

This paper presents a hybrid algorithm for solving optimal power flow(OPF) in order to enhance a systems capability to cope with outages, which is based on combined application of evolutionary computation and local search method. The efficient algorithm combining main advantages of two methods is as follows : Firstly, evolutionary computation is used to perform global exploitation among a population. This gives a good initial point of conventional method. Then, local methods are used to perform local exploitation. The hybrid approach often outperforms either method operating alone and reduces the total computation time. The objective function of the security constrained OPF is the minimization of generation fuel costs and real power losses. The resulting optimal operating point has to be feasible after outages such as any single line outage(respect of voltage magnitude, reactive power generation and power flow limits). In OPF considering security, the outages are selected by contingency ranking method(contingency screening model). The OPF considering security, the outages are selected by contingency ranking method(contingency screening model). The method proposed is applied to IEEE 30 buses system to show its effectiveness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.998-1004
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• 2004

In this paper we propose a discrete bit-loading algorithm that maximizes the transmit bit rate using the channel information. to optimize the performance of the very high-speed digital subscriber line(VDSL) system under the constraint of a maximum transmit power for each user. When the power level of crosstalk is high, the power allocation of a user changes the crosstalk experienced by the other users in the same binder. In this case, the performance of DSL modems can be improved by jointly considering the bit and power allocation of all users Simulation results shows that the proposed method improves the performance compared With that of iterative water-filling method.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.4
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• pp.113-119
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• 2001

Ammonia emissions during composting of hog manure mixed with sawdust were studied in four runs comprising a total of 22 pilot-scale reactor vessels. These four runs extended previous work and both verified and extended the previous conclusions. The pilot-scale vessels were 205 L insulated stainless steel drums that were aerated either continuously (high/low thermostatically controlled fans) or intermittently (5 min high fan 55 min off). Temperature ammonia emissions air flow rates carbon dioxide production and oxygen utilization moisture and dry matter reduction initial and final chemical compositions were measured. Ammonia emissions from the intermittently aerated vessels were only about 50% as great as those from the continuously aerated ones but this was found to be a result more related to total air flow than to aeration technique. All of the data for total result more related to total air flow were fitted with a linear regression line y=0.139x+29.835 where y is ammonia expressed as g of N and x is air flow in kg with $R^2$=0.6808. this general trend indicates that about 50% reduction in ammonia emissions can be achieved with 75% reduction in air flow. For the aeration techniques used the minimum oxygen level in te exhaust gas from the vessels was 5% and this is probably a resonable lower limit constraining air flow reduction. However within this constraint lower air flow now appears to be a technique that can reduce odorous ammonia emissions.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.70.4-71
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• 2016

The links between super-massive black hole masses and their host galaxy properties are observed, indicating that black hole growth and host galaxy evolution are closely related. Reverberation mapping, which uses the time delay from the central black hole to broad line regions, is one of the best methods to estimate masses of black holes of active galactic nuclei (AGNs). However, only masses of about 50 black holes have been determined in reverberation mapping studies so far, and most of them are limited to optical luminosities below 10^45 erg/s due to the challenges of long-term time domain observations in both photometry and spectroscopy. In this project, we expand reverberation mapping samples to higher luminosities of > 10^44.5 erg/s at 0.1 < z < 0.35, that have expected time lags of 40 - 250 light days. Photometric (using LOAO 1-m and MDM 1.3-m) and spectroscopic (using MDM 2.4-m and Lick 3-m) monitoring campaigns are being conducted for a 3 year duration and 20 day cadence. Precedent photometric observations in 2015B show some targets with variability and follow-up spectroscopic observations are on-going. In this presentation, we introduce our project, present reverberation mapping simulation results, and preliminary results on photometry. These reverberation mapping masses of relatively high luminous AGNs will provide a strong constraint on black hole mass calibration, e.g., the single-epoch mass estimation.