• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.18 no.1
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• pp.1-15
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• 2014

We have investigated optimal control strategies for prevention of ecstasy use. Ecstasy use has continued at raves and nightclubs in recent years and the reduction of ecstasy use has become one of the important issues in society. We apply optimal control theory to a model of the peer-driven dynamics of ecstasy use. Our goal is to minimize the ecstasy use class and the intervention cost. Optimal control is characterized in terms of the solution of optimality system, which is the state system coupled with the adjoint system and the optimality equations. The numerical simulations show the optimal prevention policies of ecstasy use in various scenarios.

• Journal of Korea Port Economic Association
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• v.22 no.1
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• pp.1-15
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• 2006

This paper analyzes how levels of logistics standardization are related to logistics costs. The study surveyed ratios of standard pallet use in order to measure levels of firms' standardization in logistics management. Research focused on how firms' logistics costs were related to their levels of logistics standardization and ratios of standard pallet use. After measuring use of standard pallets and logistics costs, optimal levels of logistics standardization were estimated based on survey data. Logistics costs and standardization were more related to labor than to freight volume or export. Results indicated that firms could reduce logistics costs by raising levels of logistics standardization; optimal levels of standard pallet use out of Korean firms' total manufacturing cargo volume were estimated at 44.26% for multi-standard pallets and 57.99% for a single standard pallet (a unit load system). The study demonstrated that adopting a single standard pallet results in better cost saving logistics systems than use of multi-standard pallet types. These results may explain why firms pursue standardization in logistics systems.

• Journal of applied mathematics & informatics
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• v.13 no.1_2
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• pp.183-194
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• 2003

We will explain a new method for obtaining the nearly optimal domain for optimal shape design problems associated with the solution of a nonlinear wave equation. Taking into account the boundary and terminal conditions of the system, a new approach is applied to determine the optimal domain and its related optimal control function with respect to the integral performance criteria, by use of positive Radon measures. The approach, say shape-measure, consists of two steps; first for a fixed domain, the optimal control will be identified by the use of measures. This function and the optimal value of the objective function depend on the geometrical variables of the domain. In the second step, based on the results of the previous one and by applying some convenient optimization techniques, the optimal domain and its related optimal control function will be identified at the same time. The existence of the optimal solution is considered and a numerical example is also given.

• Journal of Korea Water Resources Association
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• v.35 no.4 s.129
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• pp.367-374
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• 2002

Water supply plan by optimal conjunctive use of surface and ground water is studied to prepare expected water deficit in near future. The optimization model for conjunctive use of surface and ground water is developed using discrete differential dynamic programming technique to maximize net benefit by water supply. As a result of applying the model to Namdaechun river located in Yangyang, it is found that water supply reliability using optimal conjunctive use of surface and ground water is much higher than reliability using surface water alone.

• Korean Journal of Remote Sensing
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• v.25 no.6
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• pp.465-474
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• 2009

Convective/stratiform radar echo classification schemes by Steiner et al. (1995) and Biggerstaff and Listemaa (2000) are examined on a monsoonal front during the summer monsoon-Changma period, which is organized as a cloud cluster with mesoscale convective complex. Target radar is S-band with wavelength of 10cm, spatial resolution of 1km, elevation angle interval of 0.5-1.0 degree, and minimum elevation angle of 0.19 degree at Jindo over the Korean Peninsula. For verification of rainfall amount retrieved from the echo classification, ground-based rain gauge observations (Automatic Weather Stations) are examined, converting the radar echo grid data to the station values using the inverse distance weighted method. Improvement from the echo classification is evaluated based on the correlation coefficient and the scattered diagram. Additionally, an optimal use method was designed to produce combined rainfalls from the radar echo and Tropical Rainfall Measuring Mission Precipitation Radar (TRMM/PR) data. Optimal values for the radar rain and TRMM/PR rain are inversely weighted according to the error variance statistics for each single station. It is noted how the rainfall distribution during the summer monsoon frontal system is improved from the classification of convective/stratiform echo and the use of the optimal use technique.

• Korean Journal of Veterinary Research
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• v.26 no.2
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• pp.245-249
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• 1986

The present study has been carried out to investigate the optimal condition on the blastogenesis of guinea pig lymphocytes. A microculture system in conjunction with a semiautomatic multiple sample harvester(SAMSH) was used to study the in vito optimal condition of guinea pig lymphocytes. Data were presented to show many variables that are Involved in studying the responses of guinea pig lymphocyte in a microculture system to the stimulation of Concanavalin A(Con A) and lipopolysaccharide (LPS). Analysis indicated that the conditions for optimal Con A as measured by incorporation of $^3H$-TdR include : (1) use of RPMI-1640 as culture medium, (2) use of $6{\mu}g$ of Con A, per culture, (3) use of $1{\times}10^6$ cells per culture. Conditions for optimal stimulation with LPS mitogen were similar to those used for Con A.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.1
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• pp.95-108
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• 1991

For the case where the lifetime at a constant stress level has exponential distribution, optimal accelerated life test plans are developed under the assumptions of intermittent inspection and Type I censoring. In a optimal plan, the low and high stress levels, the proportion of test units allocated and the inspection times at each stress are determined such that the asymptotic variance of the maximum likelihood estimator of logarithmic transformed mean at the use condition is minimized. In addition to the optimal plan in which numerical technique to solve the set of nonlinear equations must be employed to determine inspection times at each stress level, we also propose another plans which employ equally-spaced or equal probability inspection schemes at two overstress levels of corresponding optimal one. For both optimal and proposed plans, computational results indicate that the asymptotic variance of the estimated mean at the use stress is insensitive to number of inspections at overstress levels for the range of parameter values considered.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1157-1160
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• 2003

We proposed a study on optimal clock period selection algorithm for low power RTL design. The proposed algorithm use the way of maintaining the throughput by reducing supply voltage after improve the system performance in order to minimize the power consumption. In this paper, it select the low power to use pipeline in the transformation of architecture. Also, the algorithm is important the clock period selection in order to maximize the resource sharing. however, it execute the optimal clock period selection algorithm.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.442-449
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• 1998

Since it is essential for traction motors to reduce size and weight to achieve given traction effort, they need high input voltage. But the lack of input voltage occurs periodically due to the characteristics of train system. Therefore traction inverters use over-modulation PWM to maximize inverter's voltage gain. On the other hand, IGBT inverters can use higher frequency twice than GTO ones, which resulted in the need for novel optimal synchronous PWM strategy. This paper suggests that linearly-compensated overmodulation/optimal synchronous PWM strategy and also the simulation results of the method for a real traction motor-intertia model are presented.

• Journal of Korean Society of Rural Planning
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• v.14 no.2
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• pp.55-64
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• 2008

This study aims to analyze the sensitivity of WSM(weighted scenario method)-AHP method according to variation of nonlinear exponent for accessibility criteria, which are used to make urbanization potential maps with the optimal weighting value for multiple criteria in grid-based GIS technique. Besides this study tried to develop WSM-AHP2 which is simplified by using rank of the potential value for each scenario. The two methods were applied to the test area, Suwon city located south area of Seoul, with time series land-use maps of 1986 and 1996. The evaluation system of urbanization potential have 7 criteria including 6 accessibility criteria. The results of WSM-AHP2, the optimal weighting values and their corresponding potential maps, have almost similar with those of WSM-AHP. In the application of CA(cellular automata) model for expansion of urbanized area using the three potential maps by WSM-AHP, WSM-AHP2, and specialists's AHP evaluation, it also showed that the accuracy of simulation for actual urban area is the highest in the potential map of WSM-AHP, followed by WSM-AHP2 and specialists's AHP evaluation. From the results of this study, WSM-AHP and simplified WSM-AHP2 will be used to generate the optimal potential maps for land-use planning in urban fringe area.