• Korean Journal of Mathematics
• /
• 제6권1호
• /
• pp.27-46
• /
• 1998

We are concerned with an optimal control problem governed by a Poisson equation in which body force acts like a control parameter. The cost functional to be optimized is taken to represent the error from the desired observation and the cost due to the control. We recast the problem into the mixed formulation to take advantage of the minimax principle for the duality method. The existence of a saddle point for the Lagrangian shall be shown and the optimality system will be derived therein. Finally, to attain an optimal control, we combine the optimality system with an operational technique. By achieving the gradient of the cost functional, a convergent algorithm based on the projected gradient method is established.

• 전기학회논문지
• /
• 제64권7호
• /
• pp.1125-1129
• /
• 2015

Increasing peak load is one of the major concerns about operation of urban railroad systems. Since ESSs (Energy Storage Systems) have a great potential for shaving the peak load, there has been a growing interest in the use of ESS for peak load reduction. Also, ESS can be optimally scheduled to minimize the electricity purchasing cost under a given ToU (Time-of-Use) tariff by taking advantage of electricity price difference between peak and off-peak time. This paper presents a Mixed Integer Programming (MIP)-based ESS scheduling method to minimize the electricity purchasing cost under a ToU tariff for an urban railroad system.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2002년도 전력전자학술대회 논문집
• /
• pp.451-454
• /
• 2002

In this paper, studied on the one-chip design of low cost for the micro-stepping drive having 5-phase Pentagon Type winding. Micro-stepping method in order to eliminate effectively the resonant phenomena and to Increase the positional resolution. This paper proposed trapezoidal current wave- form for current control and provided design- method by using only one-chip of low cost. Therefore the drive will be simple and small size. Also the drive will have a lot of advantage at commercial business. Finally the above study has been implemented on the VHDL. Simulation has been performed to verify the PWM for micro-stepping drive.

• 한국건설관리학회논문집
• /
• 제6권1호
• /
• pp.49-57
• /
• 2005

Construction labor productivity, which is the greatest source of variation in overall construction productivity, is the critical factor for determining the project performance in terms of time and cost, especially during scheduled overtime when extra time and cost are invested. The objective of this research is to select an appropriate type of probability distribution function representing the variability of daily labor productivity during overtime. Based on the results of statistical data analysis of labor performance during different weekly work hours, lognormal distribution is selected in order to take advantage of easiness of generating correlated random numbers. The selected lognormal distribution can be used for development of a simulation model in construction scheduling, cost analysis, and other applications areas where representation of the correlations between variables are essential.

• 수산경영론집
• /
• 제44권1호
• /
• pp.25-37
• /
• 2013

The permit system is the most typical regulation system in Korean fishery. Even now, it has caused resource management failure, it has also invited economic inefficiency and inequity. Accordingly, the Korean government has recently introduced the fishing boats market, it would be improve entry barrier for new capital and labor in fishing industry. This study aims to survey and to analyze the status of coastal fishing boat market using the executive documents on permit system in Gyongnam province. And also, this study put focus on improve fishing permit trade take advantage of the fishing boat trading. The survey results indicated that the number of fishing boats trading is estimated about 5,000 per year, however, fishing boat market is very narrow. An analysis on fishing permit trading showed that policy support is essential to reduce transaction cost. Therefore, it is necessary to explore corresponding policy tasks, this will be reduce transaction costs and sunk cost.

• Journal of Information Processing Systems
• /
• 제10권1호
• /
• pp.81-91
• /
• 2014

Widely spreading smart devices have become an important information sharing channel in everyday life. In particular, social networking services (SNS) are the hub for content creation and sharing. Users post their contents on SNS servers and receive contents of interest. Contents are delivered in either pull or push. Regarding delivery, cost and wait time are two important factors to be minimized, but they are in a trade-off relationship. The Push-N-scheme (PNS) and timeout-based push scheme (TPS) have been proposed for content delivery. PNS has an advantage in cost over TPS, whereas TPS has an edge in terms of the wait time over PNS. We propose a hybrid push scheme of PNS and TPS, called push-N-scheme with timeout (PNT), to balance the cost and the wait time. We evaluate PNT through simulations, with the results showing that PNT is effective in balancing PNS and TPS.

• Journal of Construction Engineering and Project Management
• /
• 제4권1호
• /
• pp.8-14
• /
• 2014

The Construction industry in Yemen confronts many development constraints, such as the inadequate implementation of appropriate building materials and labour construction technologies. Thus, this research looks over building materials and labour construction technologies used on the local housing construction projects by verifying the percentage of construction expenditure consumed by the main construction components (Materials, Labour and Overhead and Profit), along with the implemented construction technologies. The paper conducts a survey to acquire the cost distribution of the construction main components. The outcomes of the survey were discussed; the discussion was supported by literature on similar issues from some countries. The outcomes confirmed the relatively limited percentage in labour cost and profit, and the elevated percentage of construction materials cost, which are because of the excessive and inappropriate use of materials. What's more, established that the excessively redundant unskilled labours are not effectively engaged in the construction activities, this is due to the tendency of the market in using labour-base technologies. This paper is to recommend a suitable policies and strategies has to be used to decrease cost by using efficiently appropriate construction practice and local materials, moreover take advantage of excessive labour to reduce unemployment.

• Journal of Biosystems Engineering
• /
• 제19권4호
• /
• pp.329-342
• /
• 1994

In order to reduce the production cost and improve the quality of dairy feed, several dairy feed mill models suitable for Korean farm size were developed. 6 TMR models were developed for the 1000, 600, 200 head of dairy cattle, and evaluated for capital investments and production costs to suggest the best model. Followings are summary of this study : 1. TMR terminal models were designed that dairy production capacity of TMR1000 models are 40 ton/day, TMR600 model is 20 ton/day and TMR200 models are 10 ton/day. Also, they can be extended their capacity up to twice. 2. Capital investment of TMR terminal models is 145 million won for TMR200-1,205 million won for TMR600 and 609 million won for TMR1000-3 model. 3. The bigger TMR terminal model has the more advantage in production cost. The best model for 1000 head of dairy cattle farm was TMR1000-3 with 10,849 won/ton of production cost, TMR600 for 600 head of dairy cattle farm with 13,829 won/ton, TMR200-1 for 200 head of dairy cattle farm with 16,943 won/ton of production cost, so feed production cost for the 200 head farm was 50% higher than 1,000 head size farm.

• 산업경영시스템학회지
• /
• 제41권3호
• /
• pp.145-153
• /
• 2018

Taguchi regarded the concept of quality as 'total loss to society due to fluctuations in quality characteristics from the time of supplied to the customer.' The loss function is a representative tool that can quantitatively convert the loss that occurs due to the deviation of the quality characteristic value from the target value. This has been utilized in various studies with the advantage that it can change the social loss caused by fluctuation of quality characteristics to economic cost. The loss function has also been used extensively in the study of producer specification limits. However, in previous studies, only the second order loss function of Taguchi is used. Therefore, various types of losses that can occur in the process can't be considered. In this study, we divide the types of losses that can occur in the process considering the first and second loss functions and the Spiring's reflected normal loss function, and perform total inspection before delivering the customer to determine the optimal producer specification limit that minimizes the total cost. Also, we will divide the quality policy for the products beyond the specification limits into two. In addition, we will show the illustration of expected loss cost change of each model according to the change of major condition such as customer specifications and maximum loss cost.

• Wind and Structures
• /
• 제30권4호
• /
• pp.379-392
• /
• 2020

The paper presents a Life-Cycle Cost-based optimization framework for wind-excited tall buildings equipped with Tuned Mass Dampers (TMDs). The objective is to minimize the Life-Cycle Cost that comprises initial costs of the structure, the control system and costs related to repair, maintenance and downtime over the building's lifetime. The integrated optimization of structural sections and mass ratio of the TMDs is carried out, leading to a set of Pareto optimal solutions. The main advantage of the proposed methodology is that, differently from the traditional optimal design approach, it allows to perform the unified design of both the structure and the control system in a Life Cycle Cost Analysis framework. The procedure quantifies wind-induced losses, related to structural and nonstructural damage, considering the stochastic nature of the loads (wind velocity and direction), the specificity of the structural modeling (e.g., non-shear-type vibration modes and torsional effects) and the presence of the TMDs. Both serviceability and ultimate limit states related to the structure and the TMDs' damage are adopted for the computation of repair costs. The application to a case study tall building allows to demonstrate the efficiency of the procedure for the integrated design of the structure and the control system.