• 제어로봇시스템학회논문지
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• 제16권5호
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• pp.476-480
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• 2010

This study deals with stockout costs in the supply chain optimization model under the framework of batch-storage network. Stockout is very popular in chemical industries. Estimating stockout cost involves an understanding of customer reactions to a seller being out of stock at the time the customer wants to buy an item. This involves massively non-trivial work such as direct customer interviews and extensive mail survey. In this study, we will introduce a new interpretation of stockout costs combined with batchstorage network optimization model and thus suggest an easy way of estimating stockout costs. Optimization model suggest that optimal process and storage sizes considering stockout cost are smaller than those that do not consider stockout cost. An illustrative example support the analytical results.

• KIEE International Transactions on Power Engineering
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• 제12A권1호
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• pp.31-35
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• 2002

This paper presents a new operation scheme of UPFC to minimize both generation costs and active power losses in a normal operation state of power system. In a normal operation, cost minimization is a matter of primary concern among operating objectives. This paper considers two kinds of costs, generation costs and transmission losses. The total generation cost of active powers can be minimized by optimal power flow, and active power losses in the transmission system can be also minimized by power flow control of UPFC incorporated with minimization of generation costs. In order to determine amounts of active power reference of each UPFC required for the cost minimization, an iterative optimization algorithm based on the power flow calculation using the decoupled UPFC model is proposed. For verification of the proposed method, intensive studies have been performed on a 3-unit 6-bus system equipped with a UPFC.

• 통합자연과학논문집
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• 제9권3호
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• pp.206-214
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• 2016

The basic goal of software development is to produce high quality software at low cost. Therefore, when to stop software testing and release the software product is a significant point in the software development. The software cost model is an effective tool used to help software developers control costs and determine the release time. In this paper, we discuss the cost model to apply all 6 models with consideration of time to remove errors, cost of removing each error and risk cost due to software failure. We show the impact of cost coefficients and parameter values on the expected total cost by changing the values and comparing the optimal release times.

• 전력전자학회논문지
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• 제19권5호
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• pp.470-474
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• 2014

This study proposes an improved synchronization control scheme for a low-cost 400Hz power supply for a no-break power transfer system. In the case of aircraft applications, the 400Hz power supply called ground power units is accepted and used as the external electrical power system during stopovers on ground. A momentary break in the supply occurs when shifting from one power source to another. To allow shifting without a break in the supply, the two power sources are momentarily connected in parallel. The proposed synchronization control is achieved by connecting an existing synchronization bus to the voltage zero-crossing signal of a generator power with discrete logic ICs and analog circuits. Therefore, unlike expensive controllers, such as DSP and CAN, the proposed control scheme is rather simple and may decrease operational cost. The practical feasibility of the proposed control scheme is proven by experimental results.

• 경영과학
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• 제31권2호
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• pp.1-13
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• 2014

In almost all of the organizations, the cost for acquiring and maintaining the inventory takes a considerable portion of the management budget, and thus a certain constraint is set upon the budget itself. The previous studies on inventory control for each item that aimed to improve the fill rate, backorder, and the expenditure on inventory are fitting for the commercially-operated SCM, but show some discrepancies when they are applied to the spare parts for repairing disabled systems. Therefore, many studies on systematic approach concept considering spare parts of various kinds simultaneously have been conducted to achieve effective performance for the inventory control at a lower cost, and primarily, METRIC series models can be named. However, the past studies were limited when dealing with the probability distributions for representing the situation on demand and transportation of the parts, with the (S-1, S) inventory control policy, and so on. To address these shortcomings, the Continuous Time Markov Chain (CTMC) model, which considers the phase-type distributions and the (s, Q) inventory control policies to best describe the real-world situations inclusively, is presented in this study. Additionally, by considering the cost versus the system availability, the optimization of the inventory level, based on this model, is also covered.

• 대한안전경영과학회지
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• 제20권3호
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• pp.1-9
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• 2018

This study is intended to look into the effect of construction safety supervision system on risk control and reduction. To achieve this, a survey was carried out to 114 companies in construction, ordering, contract and management. The overall findings were as follows. The effect of construction safety supervision system on risk control and reduction showed that factors of supervision system, supervision cost and supervision method had a positive effect on risk control and reduction. And their perception of the introduction of safety supervision system in construction sites according to process showed that there was a difference between them according to the field of ordering, contract and supervision. There was the biggest difference between owner and contractor in double supervision system, but no difference between them in the perception of risk reduction. These results show that all ordering, contract and supervision are positively needed for the introduction of construction safety supervision. This means that there is a difference between owner and contractor in the perception of process according to system operation. All companies agree to system improvement by the settlement of safety supervision system for the prevention of safety accidents and safe construction, but the systematic complement of safety supervision is the burden of contractor. And there is a big difference between owner and contractor in the perception of responsibility and concern for cost burden.

• 한국건설관리학회논문집
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• 제5권2호
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• pp.153-161
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• 2004

대형 건설프로젝트의 효율적인 운용을 위해서는 프로젝트 각 분야간의 유기적인 관리체계가 필수적이라 할 수 있다. 대형 건설프로젝트의 관리업무 중 일정, 비용, 자재, 노무관리업무는 상호 유기적 종합관리를 가능하게 하는 업무들이며 이들을 종합적으로 $분석\cdot평가$할 수 있는 데이터 중심의 정보교환체계가 필수적이라 할 수 있다. 건설프로젝트관리의 $비용\cdot일정관리$업무에서 발생하는 자료의 중요성 및 활용빈도는 타 관리보다 높으며 건설공사의 효과적인 수행에 미치는 영향이 크다. $비용\cdot일정$ 통합데이터 통합관리를 통한 건설프로젝트관리체계를 수립하는 것은 생산성 측면과 자료 활용도 측면에서 더욱 효과적이라 할 수 있다. 본 논문에서는 $비용\cdot일정$ 통합 데이터베이스를 기반으로 하고 비용, 일정, 자재, 노무관리에 관련된 현장업무 분석을 통하여 대형건설공사의 프로세스 및 데이터 모델링을 통한 제반 필요정보의 분석 및 구조화를 제시하고자 한다.

• Infection and chemotherapy
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• 제50권4호
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• pp.319-327
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• 2018

Background: Lancet-related needlestick injuries (NSIs) occur steadily in clinical practices. Safety-engineered devices (SEDs) can systematically reduce NSIs. However, the use of SEDs is not active and no study to guide the implementation of SEDs was known in South Korea. The lancet-related NSIs may be eliminated to zero incidence using a SED lancet with effective sharp injury protection and reuse prevention features. Materials and Methods: We implemented a SED lancet by replacing a conventional prick lancet in a tertiary hospital in a sequential approach. A spot test of the new SED was conducted for 1 month to check the acceptability in practice and a questionnaire survey was obtained from the healthcare workers (HCWs). A pilot implementation of the SED lancet in 2 wards was made for 1 year. Based on these preliminary interventions, a hospital-wide full implementation of the SED lancet was launched. The incidence of NSIs and cost expenditure before and after the intervention were compared. Results: There were 29 cases of conventional prick lancet-related NSIs for 3 years before the full implementation of SED lancet. The proportion of prick lancet-related NSIs among yearly all kinds of NSIs during two years before the pilot study was average 11.7% (22/188). Pre-interventional baseline incidence of all kinds of NSIs was 7.01 per 100 HCW-years. After the full implementation of SED lancet, the lancet-related NSIs became zero in the 2nd year (P = 0.001). The average direct cost of 18,393 US dollars (USD) per year from device and post-exposure medical care before the intervention rose to 20,701 USD in the 2nd year of the intervention. The incremental cost-effectiveness ratio was 210 USD per injury avoided. Conclusion: The implementation of a SED lancet could eliminate the lancet-related NSIs to zero incidence. The cost increase incurred by the use of SED lancet was tolerable.

• Journal of Mechanical Science and Technology
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• 제17권1호
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• pp.23-31
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• 2003

This paper introduces a constraint operator for the kinematic calibration of a parallel mechanism. By adopting the concept of a constraint operator, the movement between two poses is constrained. When the constrained movements are satisfied, the active joint displacements are taken and inputted into the kinematic model to compute the theoretical movements. A cost function is derived by the errors between the theoretical movement and the actual movement. The parameters that minimize the cost function are estimated and substituted into the kinematic model for a kinematic calibration. A single constraint plane is employed as a mechanical fixture to constrain the movement, and three digital indicators are used as the sensing devices to determine whether the constrained movement is satisfied. This calibration system represents an effective, low cost and feasible technique for a parallel mechanism. A calibration algorithm is developed with a constraint operator and implemented on a parallel manipulator constructed for a machining center tool.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.447-450
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• 2002

A study on control of BLDC Is studying In progress, because of radical increase of survo motor at industrial machine and home machine. Nowaday, we study on control of BLDC, because of radical increase of survo motor at Industry and home. Although control ratio and output of the unit volume are good than the others , BLDC motor demands high cost. Therefor, the study on low cost BLDC have square wave back-emf is studing in progress. Therefor, BLDC Motor was studied to reduce high cost that have square wave back-emf at recently. This paper shows that BLDC Motor, developed highly responsility by using Genetic Algorithm(GA) that the advantages of learning ability, Also, this paper shows experiment and simulation at 200W BLDC that have squarewave back-emf by using Genetic Algorithm. At the result of this methods, the study prove experiment's right.