• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2168-2177
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• 2018

The unavoidable forecast error of wind power is one of the biggest obstacles for wind farms to participate in day-ahead electricity market. To mitigate the deviation from forecast, installation of energy storage system (ESS) is considered. An accurate model of wind power forecast error is fundamental for ESS sizing. However, previous study shows that the error distribution has variable kurtosis and fat tails, and insufficient measurement data of wind farms would add to the difficulty of modeling. This paper presents a comprehensive way that makes the use of mixed skewness model (MSM) and copula theory to give a better approximation for the distribution of forecast error, and it remains valid even if the dataset is not so well documented. The model is then used to optimize the ESS power and capacity aiming to pay the minimal extra cost. Results show the effectiveness of the new model for finding the optimal size of ESS and increasing the economic benefit.

• 한국항해항만학회지
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• 제33권1호
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• pp.79-90
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• 2009

컨테이너 터미널의 핵심 기능은 컨테이너 화물을 선반에 싣고 내기는 것이다. 이러한 기능에 대한 생산성을 향상시키기 위해서는 보유한 자원을 효과적으로 사용해야 하는데, 본 연구는 RMGC (rail mounted gantry crane) 유형 야드 크레인의 배치 방안에 대해서 논한다. 먼저, 컨테이너 터미널의 장치계획을 고려한 야드 크레인 배치 문제에 대한 수리모형을 개발한다. 수리 모형은 한 기간 내에서 블록간 야드 크레인의 이동 허용여부에 따라서 2가지로 나누어진다. 제시한 모형을 검증하기 위하여 수치 예제를 풀어서 결과를 분석한다. 또한 장치계획만을 다루는 기존 모형과의 성능 차이를 분석하기 위한 비교 실험을 수행한다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2003년도 추계학술대회 및 정기총회
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• pp.81-84
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• 2003

The ability to determine the optimal frequencies and offsets for independent and unrestricted ordering cycles for multiple items can be very valuable for managing storage capacity constrained facilities in a supply chain. The complexity of this problem has resulted in researchers focusing on more tractable surrogate problems that are special cases of the base problem. Murthy et al. (European Journal of Operation Research 2003) developed insights leading to solution of the original problem and present a heuristic for offsetting independent and unrestricted ordering cycles for items to minimize their joint storage requirements. However, their study cannot find optimal solution due to the Greedy Heuristic solution procedure. In this paper, we present a complete procedure to find the optimal solution for the model with a integer programming optimization approach and genetic algorithm. Numerical examples are included to compare each model with that of Murthy et at. Research of this type may prove useful in solving the more general problem of selecting order policies to minimize combined holding, ordering, and storage costs.

• 경영과학
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• 제30권3호
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• pp.99-111
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• 2013

This paper studies the scheduling problem of storing and retrieving assembly blocks in a temporary storage yard. The objective is to minimize the number of relocations of blocks while the constraints for storage and retrieval time windows are satisfied. We present an integer programming model based on multi-commodity network flows, and the three revised models based on the properties of the problem. We show that the revised models are more efficient than the generic model through the numerical experiments.

• 대한산업공학회지
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• 제24권1호
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• pp.137-144
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• 1998

Block stacking, which involves the storage of unit loads in stacks within storage rows, is typically used in traditional warehouses to achieve a high space utilization at a low investment cost. In this paper, assuming that the demand size from a customer is an i.i.d. random variable, we develop a probabilistic block stacking storage model and its algorithm for a singles product, which minimizes the time-overage floor space requirement under an (s, S) inventory policy and the violation of the FIFO lot rotation rule only in a single partially-occupied row.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.963-967
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• 2007

Flywheel energy storage systems (FESS) have advantages over other types of energy storage methods due to their infinite charge/discharge cycles and environmental friendliness. The system has two radial bearings and one hybrid-thrust bearing. Thrust hybrid-type bearing use permanent magnet to relieve gravity load. The radial bearings were designed to provide sufficient force slew rate considering the unbalance disturbance at the operating speeds. In this paper, we will derive dynamic model of hybrid-type bearing using permanent magnet for thrust bearing and present simulation and stability of the model.

• Wind and Structures
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• 제5권2_3_4호
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• pp.89-100
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• 2002

Accidental gaseous losses from industrial processes can pose considerable health and environmental risks but assessing their health, safety and environmental impact is problematic. Improved understanding and simulation of the dispersion of emissions in the vicinity of storage tanks is required. The present study aims to assess the capability of the turbulence closures and meshing alternatives in a commercially available CFD code for predicting dispersion in the vicinity of cubes and circular cylindrical storage tanks. The performance of the $k-{\varepsilon}$ and Reynolds Stress turbulence models and meshing alternatives for these cases are compared to experimental data. The CFD simulations are very good qualitatively and, in many cases, quantitatively. A mesh with prismatic elements is more accurate than a tetrahedral mesh. Overall the Reynolds stress model performs slightly better than the $k-{\varepsilon}$ model.

• 농촌계획
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• 제10권3호
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• pp.53-58
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• 2004

In this study the effect caused by limited storage lift of agricultural products for determining shipping amount can be analyzed by $l^{st}$ order autoregressive model based on cobweb theorem. Carrying capacity and auction price of upland-grown cabbage and garlic from 2000 to 2003 in wholesale markets were used for analysis. In result regression models of cabbage can not be used in verification periods although those of garlic approximately predicted shipping amounts in verification periods. It can be inferred that it is hard to control shipping amounts depending on price fluctuation for agricultural products which have limited storage life so cultivated areas and meteorological risk should be managed for stable price.

• 한국식품영양과학회지
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• 제19권5호
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• pp.387-394
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• 1990

The effect of lysine or methionine addition on the lipid oxidation and protein properties in casein-fish oil model system during the storage of 21 days at 37$^{\circ}C$ was studied. The peroxide and TBA values were increased markedly and the amino acids addition to the system caused to reduce the extent of lipid oxidation in comparison with that of casein-fish oil system which was a control group. Significant changes in fatty acid composition of each group were observed. Polyenoic acid contents were drastically decreased during the storage in the groups with and without the amino acids additions, . And also significant losses of several amino acids were occurred with the reduction of solubility and digestibility of casein during the storage. However no different effects were observed in both additionsof lysine and methionine to the system.

• 한국자동차공학회논문집
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• 제12권5호
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• pp.79-84
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• 2004

We evaluated the reduction performance of NOx storage catalyst and TWC for lean-burn natural gas engine by the model gas. The method of unsteady state reaction was used to compare with reduction performances of NOx storage catalyst and TWC. It was found that the effective parameter was rich spike duration, temperature of the model gas. In the presence of $CO_2$ and $H_2O$ in the reaction mixture was decreased the NOx reduction performance.