• International Journal of Reliability and Applications
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• 제4권1호
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• pp.13-26
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• 2003

This paper presents a comparative study of a few commonly used maintenance scheduling methods for small utilities that consists solely of thermal generating plants. Two deterministic methods and a stochastic method are examined. The deterministic methods employ the leveling of reserve capacity criterion, of which one uses a heuristic rule to level the deterministic equivalent load obtained by using the product of the unit capacity and its corresponding forced outage rate. The stochastic method simulates the leveling of risk criterion by using the peak load carry capacity of available units. The results indicate that for the size and type of the maintenance scheduling problem described In this study, the stochastic method does not produce a schedule which is significantly better than the deterministic methods.

• 한국지반공학회지:지반
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• 제40권2호
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• pp.37-41
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• 2024

• Tribology and Lubricants
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• 제35권6호
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• pp.369-375
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• 2019

This paper presents a new method on how to calculate the thrust forces acting on an auto-leveling device in headlamps for passenger vehicles. The leveling device is used to lower the angle of lights when a load in the trunk of the vehicle lifts it. In the process of the headlamp design, it is imperative to predict the external forces so that the designers can decide whether to proceed or not. The device is composed of three pivot joints with no reaction moment, a plate that holds the lamp, and a leveling motor that changes rotation to linear motion. In this study, force balance, moment balance, and geometric compatibility are applied to the leveling device system so that a nonlinear system of equations can be derived; the multi-dimensional Newton-Raphson algorithm is then used to solve these. A sensitivity analysis is carried out to verify which design variables affect the system the most: the mass of the lamp and the height between the pivot and leveling device affect the thrust forces the most. Then, considering the friction forces between the moving parts, the hysteresis of the forces are derived. An experimental apparatus, designed and developed in this study, is used to verify the exactness of the derived equations. The results from experiments coincide well with the calculated results. The friction hysteresis, in particular, proves this upon analysis.

• 대한조선학회논문집
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• 제32권1호
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• pp.9-16
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• 1995

탑재 공정 계획은 도크 공기를 만족토록 탑재 전략과 탑재 블록 순서를 결정하는 것이며, 탑재일정 계획은 결정된 탑재 순서에 따라 블록의 탑재일을 결정하는 것이다. 일정 계획에 따라 부하 분포가 다양한 양상을 보이며, 이는 생산 비용에 영향을 미친다. 제한된 가용 자원을 효율적으로 사용하면서 최단 공기에 탑재를 완료할 수 있는 최적의 공정 계획을 수립하기 위해서는 공정 계획과 일정 계획의 다양한 조합에 대해 시뮬레이션해 볼 수 있어야 한다. 최적 탑재 공정 계획 시스템 구축을 위해서는 탑재 순서를 자동으로 생성하는 시스템과 부하 평준화 시스템이 요구된다. 본 논문에서 탑재 순서 자동 생성 방안을 약술하였다. 부하 평준화는 같은 도크 기간에 건조하는 모든 선박에 대해 동시에 행하여야 신뢰성 있는 결과를 얻을 수 있다. 이럴 경우 탐색 범위가 매우 넓어짐으로 효율적인 최적화 기법이 필요하다. 본 연구에서는 유전 알고리즘을 이용한 부하 평준화 시스템을 구현하였다. 본 시스템 개발로 일정 계획이 고려된 다양한 공정 계획 시뮬레이션이 가능하다.

• 전기학회논문지
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• 제63권2호
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• pp.211-216
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• 2014

Construction of power plants and T&D facilities is so difficult because of the civil complaints and the additional cost according to the concerning field conditions. Therefore, various researches and methods have been considered to get solutions in the demand side and energy storage systems have been in the spotlight because of the various functions such as peak shaving, load shifting, and power system stabilizing, and so on. Residential small size batteries are considered in this paper and the economic analysis is carried out to evaluate the reasonable subsidy levels for the deployment of energy storage systems. Various economic parties are considered to find reasonable subsidy level comparing each other, which parties consist of utilities, participants and non-participants in general. The evaluation is based on California Standard Practice Test and the results are able to be used as subsidy guidelines.

• International Journal of Automotive Technology
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• 제6권4호
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• pp.429-436
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• 2005

In this paper, operation algorithms are evaluated for a fuel cell hybrid electric vehicle (FCHEV). Power assist, load leveling and equivalent fuel algorithm are proposed and implemented in the FCHEV performance simulator. It is found from the simulation results that the load leveling algorithm shows poor fuel economy due to the system charge and discharge efficiency. In the power assist and equivalent fuel algorithm, the fuel cell stack is operated in a relatively better efficiency region owing to the battery power assist, which provides the improved fuel economy.

• 조명전기설비학회논문지
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• 제27권2호
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• pp.7-13
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• 2013

The portion of lighting power consumption for our country is up to 20~30% of the total amount. Currently, most of the DSM(Demand side management) of lighting power is delivered in supply of high efficient lighting to customers. On the contrary, applications of lighting power to power load leveling are still rare. In this paper, the simulations for various control types of lighting power for load leveling are tried, and we obtained the cost effective and optimal control method through that. This simulation was executed in test office with fluorescent light by us based on applying 8 control types(on, off & dimming), considering customers' satisfaction, for instance, minimum intensity of illumination allowed. According to the result of this test, we found that mixed type(chessboard(on-off) plus dimming control(10%)) is most effective.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.538-539
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• 2014

The development of smart grid technologies will enable enhanced utilization of electric vehicles(EV) as portable energy storage devices which can provide power system-wide. Because significant increase of EV in the near future, V2G(Vehicle-to-Grid) system will soon become a reality. This paper presents the optimal method of a battery lifetime depending on depth of discharge(DOD) considering load leveling.

• 한국지열·수열에너지학회논문집
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• 제15권1호
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• pp.9-17
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• 2019

Reducing global warming potential has become important, and as one of those methods for reducing it, economic evaluation by applying ice thermal storage air conditioning system was performed. The floor area and height of the subject building was assumed $5,000m^2$ and 20 m. Absorption chillerheater system and air source heat pump system was used for comparing to the subject system, and payback period method was used to perform economic evaluation. Although the running cost of ice thermal storage system is reduced compared to two systems, the ratio is not significant compared to the increase of initial construction expenses, and payback period was calculated to be about 7.7 and 79.3 years. However, the heat storage system should be approached from the viewpoint of long term rather than the economic standard in the present standard.

• 전기화학회지
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• 제3권4호
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• pp.241-245
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• 2000

비정질 $MnO_2\;nH_2O$ 전극재료를 사용한 pseudo-capacitor를 설계 제작하여 특성을 평가하였다. 100mV/s의 cyclic voltammogram으로부터 측정한 결과, 이 전극재료의 안정한 potential window는 1V이고 비용량은 250F/g이었다. TDMA(Time Division Multiplex Algorithm) pulse 시험에서 TDMA 시스템 (2 parallel-pseudo-capacitor systems) 은 0.22V의 ohmic voltage drop과 0.38V의 capacitor voltage drop을 보여주었다. 이 TDMA system의 total voltage drop이 0.60V이므로 TDMA 위성통신 휴대전화의 요건인 1V maximum voltage drop을 충족하였다. 또한, 이 system의 ESR과 비용량은 각각 $55m{\Omega}$과 105mF이었다. 따라서 이 TDMA system이 위성통신 휴대전화를 위한 load-leveling 캐패시터로 응용 가능함을 확인하였다.